IPAC2012 - List of Keywords (electron)

Paper	Title	Other Keywords	Page
MOYBP01	State-of-the-Art and Future Prospects in RF Superconductivity	cavity, SRF, niobium, storage-ring	11
	K. Saito KEK, Ibaraki, Japan
	This presentation should recount the remarkable progress in improving the performance of superconducting cavities over the past 50 years and explore future directions, including advances in materials other than Nb, such as MgB2 and novel multi-layer superconductor-insulator systems. This talk should provide an overview of international activities.
	Slides MOYBP01 [10.097 MB]

MOYCP01	Design and Simulation of IOTA - a Novel Concept of Integrable Optics Test Accelerator	focusing, betatron, optics, simulation	16
	S. Nagaitsev, A. Valishev Fermilab, Batavia, USA V.V. Danilov ORNL, Oak Ridge, Tennessee, USA D.N. Shatilov BINP SB RAS, Novosibirsk, Russia
	The use of nonlinear lattices with large betatron tune spreads can increase instability and space charge thresholds due to improved Landau damping. Unfortunately, the majority of nonlinear accelerator lattices turn out to be nonintegrable, producing chaotic motion and a complex network of stable and unstable resonances. Recent advances in finding the integrable nonlinear accelerator lattices have led to a proposal to construct at Fermilab a test accelerator with strong nonlinear focusing which avoids resonances and chaotic particle motion. This presentation will outline the main challenges, theoretical design solutions and construction status of the Integrable Optics Test Accelerator underway at Fermilab.
	Slides MOYCP01 [2.816 MB]

MOOAA01	Performance of the Cornell High-Brightness, High-Power Electron Injector	cathode, gun, emittance, laser	20
	B.M. Dunham, A.C. Bartnik, I.V. Bazarov, L. Cultrera, J. Dobbins, C.M. Gulliford, G.H. Hoffstaetter, R.P.K. Kaplan, V.O. Kostroun, Y. Li, M. Liepe, X. Liu, F. Löhl, P. Quigley, D.H. Rice, E.N. Smith, K.W. Smolenski, M. Tigner, V. Veshcherevich, Z. Zhao CLASSE, Ithaca, New York, USA S.S. Karkare, H. Li, J.M. Maxson Cornell University, Ithaca, New York, USA
	Funding: NSF DMR-0807731 The last year has seen significant progress in demonstrating the feasibility of a high current, high brightness photoinjector as required for the Energy Recovery Linac driven X-ray source at Cornell University. Both low emittances (0.4 mm-mrad rms normalized for 100% of the beam at 20 pC per bunch and 0.15 mm-mrad rms core emittance with 70% of the beam, and twice these values at 80 pC per bunch) and high average currents with a good lifetime well in excess of 1000 Coulombs at 5 MeV, 20 mA have been demonstrated. If these beams can be accelerated to 5 GeV without diluting the phase space, it would already provide a beam brightness higher than any existing storage ring. Operational experience, results, and the outlook for the future will be presented.
	Slides MOOAA01 [1.424 MB]

MOOAA03	Fast Feedback Strategies for Longitudinal Beam Stabilization	feedback, controls, laser, free-electron-laser	26
	S. Pfeiffer, M.K. Bock, H. Schlarb, Ch. Schmidt DESY, Hamburg, Germany W. Jałmużna TUL-DMCS, Łódź, Poland G. Lichtenberg, H. Werner TUHH, Hamburg, Germany
	The key for pump-probe and seeding experiments at Free Electron Lasers such as FLASH is a femtosecond precise regulation of the bunch arrival time and compression. To maintain this beam based requirements, both for a single bunch and within a bunch train, it is necessary to combine field and beam based feedback loops. We present in this paper an advancement of the currently implemented beam based feedback system at FLASH. The principle of beam based modulation of the RF set point can be superimposed by a direct feedback loop with a beam optimized controller. Recent measurements of the achieved bunch arrival time jitter reduction to 20 fs have shown the performance gain by this direct feedback method . The combination of both approaches will be presented and possible advantages are discussed. C. Schmidt et al., “Feedback Strategies for Bunch Arrival Time Stabilization at FLASH Towards 10 fs,” FEL’2011, Shanghai, August 2011, THPA26, http://www. JACoW.org.
	Slides MOOAA03 [0.544 MB]

MOOBA03	Development of a High-power Coherent THz Sources and THz-TDS System on the basis of a Compact Electron Linac	radiation, polarization, linac, laser	37
	M. Kumaki, K. Sakaue, M. Washio RISE, Tokyo, Japan R. Kuroda, H. Toyokawa, K. Yamada AIST, Tsukuba, Ibaraki, Japan
	The high-power terahertz time-domain spectroscopy (THz-TDS) has been developed on the basis of a compact S-band electron linac at AIST, Japan. It is strongly expected for inspection of dangerous materials in the homeland security field. The linac consists of a photocathode rf-gun, two acceleration tubes and a magnetic bunch compressor. The 40 MeV, 1 nC electron bunch is generated and compressed to less than 1 ps. THz radiations are generated in two methods with the ultra-short bunch. One is THz coherent synchrotron radiation (CSR). The other is THz coherent transition radiation (CTR). In the preliminary experiment, it was observed that the focused CTR had the donut profile in a transverse fields due to its initial radial polarization, so that it made Z-polarization. In case of the THz-TDS experiment, CTR was controlled to linearly polarization with the polarizer and focused to an EO crystal to obtain a THz temporal waveform which leads to THz spectrum with Fourier transform. The timing measurement between CTR and a probe laser was realized with OTR using a same optical photodiode. In this conference, we will describe details of our linac and results of the THz-TDS experiment.
	Slides MOOBA03 [3.342 MB]

MOOAB01	A Proton-driven Plasma Wakefield Accelerator Experiment with CERN SPS Bunches	plasma, proton, wakefield, acceleration	40
	P. Muggli MPI, Muenchen, Germany
	Funding: Presented for the PDPWFA collaboration. Existing relativistic proton (p⁺) bunches carry large amounts of energy (kJ) and are therefore attractive as drivers for plasma-based particle accelerators, such as the plasma wakefield accelerator or PWFA. However, short (~ps) p⁺ bunches capable of driving large amplitude (~GV/m) wakefields are not available today. It was recently proposed to use long (~300ps) p⁺ bunches self-modulated at the plasma wavelength by a transverse two-stream instability in a high-density (~10¹⁴-10¹⁵/cc) plasma to resonantly drive wakefields. Based on this idea and on the long term prospect for short p⁺ bunches a p⁺-driven PWFA experimental program was proposed to study the acceleration of electrons to the TeV energy range. Initial experiments will use the 450GeV, 1-3·10¹¹ p⁺ bunches from the CERN SPS and plasmas 5-10m in length. The wakefields will be sampled by an externally injected, low energy (10-20MeV) electron bunch that will gain energy in the GeV range. The experimental plan, as well as the expected results will be presented. N. Kumar et al., Phys. Rev. Lett. 104, 255003 (2010).
	Slides MOOAB01 [19.595 MB]

MOOAB02	First Results from the Electron Hose Instability Studies in FACET	plasma, acceleration, wakefield, status	43
	E. Adli University of Oslo, Oslo, Norway W. An, C.E. Clayton, C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi UCLA, Los Angeles, California, USA S. Corde, R.J. England, J.T. Frederico, S.J. Gessner, M.J. Hogan, S.Z. Li, M.D. Litos, Z. Wu SLAC, Menlo Park, California, USA W. Lu TUB, Beijing, People's Republic of China P. Muggli MPI, Muenchen, Germany
	Funding: This work is supported by the Research Council of Norway and U.S. Department of Energy under contract number DE-AC02-76SF00515. We present the first results from experimental studies of the electron hose instability in the plasma-wakefield acceleration experiments at FACET. Theory and PIC simulations of an electron beam as it travels through a plasma indicate that hosing may lead to a significant distortion of the transverse phase space. The FACET dump line is equipped with a Cherenkov light based spectrometer which can resolve transverse motion as a function of beam energy. We compare the predictions from simulations and theory to the experimental results obtained.
	Slides MOOAB02 [4.654 MB]

MOOBB01	Transverse-to-longitudinal Emittance-exchange with an Energy Chirped Beam	emittance, cavity, simulation, radiation	49
	J.C.T. Thangaraj, H.T. Edwards, A.S. Johnson, A.H. Lumpkin, T.J. Maxwell, J. Ruan, J.K. Santucci, Y.-E. Sun, R.M. Thurman-Keup Fermilab, Batavia, USA
	Emittance exchange has been proposed to increase the performance of free electron lasers by tailoring the phase space of an electron beam. The principle of emittance exchange - where the transverse phase space of the electron beam is exchanged with the longitudinal phase space - has been demonstrated recently at the A0 photoinjector. The experiment used a low charge bunch (250 pC) with no energy chirp. Theory predicts an improvement in the emittance exchange scheme when the incoming beam has an energy chirp imparted on it. The energy chirp helps to overcome the thick lens effect of the deflecting mode cavity and other second order effects that might lead to an incomplete emittance exchange at higher charges. In this work, we report experimental and simulation results from operating the emittance exchange beam line using an energy chirped beam with higher charge (500 pC) at different RF-chirp settings.
	Slides MOOBB01 [2.338 MB]

MOOAC02	Status and Plans for a Superconducting RF Accelerator Test Facility at Fermilab	cryomodule, SRF, cryogenics, gun	58
	J.R. Leibfritz, R. Andrews, C.M. Baffes, K. Carlson, B. Chase, M.D. Church, E.R. Harms, A.L. Klebaner, M.J. Kucera, A. Martinez, S. Nagaitsev, L.E. Nobrega, J. Reid, M. Wendt, S.J. Wesseln Fermilab, Batavia, USA P. Piot Northern Illinois University, DeKalb, Illinois, USA
	Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy. The Advanced Superconducting Test Acccelerator (ASTA) is being constructed at Fermilab. The existing New Muon Lab (NML) building is being converted for this facility. The accelerator will consist of an electron gun, injector, beam acceleration section consisting of 3 TTF-type or ILC-type cryomodules, multiple downstream beamlines for testing diagnostics and conducting various beam tests, and a high power beam dump. When completed, it is envisioned that this facility will initially be capable of generating a 750 MeV electron beam with ILC beam intensity. An expansion of this facility was recently completed that will provide the capability to upgrade the accelerator to a total beam energy of 1.5 GeV. Two new buildings were also constructed adjacent to the ASTA facility to house a new cryogenic plant and multiple superconducting RF (SRF) cryomodule test stands. In addition to testing accelerator components, this facility will be used to test RF power systems, instrumentation, and control systems for future SRF accelerators such as the ILC and Project-X. This paper describes the current status and overall plans for this facility.
	Slides MOOAC02 [13.423 MB]

MOEPPB002	The MICE Experiment	emittance, target, solenoid, coupling	76
	A.P. Blondel DPNC, Genève, Switzerland
	Ionization Cooling is the only practical solution to preparing high brilliance muon beams for a neutrino factory or muon collider. The muon ionization cooling experiment (MICE) is under development at the Rutherford Appleton Laboratory (UK) by an international collaboration. The muon beam line has been commissioned and first measurements of emittance with particle physics detectors have been performed. The remaining apparatus is currently under construction. First results with a liquid-hydrogen absorber will be produced in 2013; a couple of years later a full cell of a representative ionization cooling channel, including RF re-acceleration, will be in operation. The design offers opportunities for tests with various absorbers and several optics configurations. Results will be compared with detailed simulations of cooling channel performance to ensure full understanding of the cooling process. on behalf of the MICE collaboration

MOEPPB008	Simulation of Hollow Electron Beam Collimation in the Fermilab Tevatron Collider	simulation, collimation, quadrupole, collider	94
	G. Stancari, I.A. Morozov, A. Valishev Fermilab, Batavia, USA D.N. Shatilov BINP SB RAS, Novosibirsk, Russia
	Funding: Fermi Research Alliance, LLC operates Fermilab under Contract DE-AC02-07CH11359 with the US Department of Energy. This work was partially supported by the US LHC Accelerator Research Program (LARP). The concept of augmenting the conventional collimation system of high-energy storage rings with a hollow electron beam was successfully demonstrated in experiments at the Tevatron. A reliable numerical model is required for understanding particle dynamics in the presence of a hollow beam collimator. Several models were developed to describe imperfections of the electron beam profile and alignment. The features of the imperfections are estimated from electron beam profile measurements. Numerical simulations of halo removal rates are compared with experimental data taken at the Tevatron.

MOEPPB014	Time Jitter Measurements in Presence of a Magnetic Chicane in the FERMI@elettra Linac	linac, FEL, laser, dipole	109
	G. Penco, P. Craievich, S. Di Mitri, M.M. Milloch, F. Rossi ELETTRA, Basovizza, Italy
	Accurate and highly stable temporal synchronization between an electron bunch and a pulse from an external seed laser is one of the key requirements for successful operation of a seeded FEL in the XUV and soft x-ray regime. These requirements become more stringent when the electron bunch is longitudinally compressed to sub-ps durations in order to increase the current for more efficient FEL action. In this paper we present experimental measurements of the electron bunch arrival time jitter after the first magnetic compressor of FERMI@Elettra seeded FEL as a function of the compression factor. The experimental behavior of the pulse-to-pulse time jitter agrees both with results from tracking code simulations and with predictions from an analytical approach that takes into account the different sources of time jitter in FERMI, namely the photoinjector drive laser, the RF accelerating cavity phases and voltages, and fluctuations in the chicane bending magnet currents. We also present predictions for the expected arrival time jitter in the final configuration of FERMI that includes two bunch compressors and for which the synchronization requirement is of order 100 fs or better.

MOPPC001	Simulation of electron-cloud heat load for the cold arcs of the large hadron collider	simulation, dipole, injection, photon	115
	G.H.I. Maury Cuna CINVESTAV, Mérida, Mexico G. Iadarola Naples University Federico II, Science and Technology Pole, Napoli, Italy G. Rumolo, F. Zimmermann CERN, Geneva, Switzerland
	The heat load due to the electron cloud in the Large Hadron Collider (LHC) cold arcs is a concern for its performance near and beyond nominal beam current. We report the results of simulation studies, which examine the electron-cloud induced heat load for different values of low-energy electron reflectivity and secondary emission yield at injection energy, as well as at beam energies of 4 TeV and 7 TeV, for two different bunch spacing: 25 ns and 50 ns. Benchmarking the simulations against heat-load observations at different beam energies and bunch spacing allows an estimate of the secondary emission yield in the cold arcs of the LHC and of its evolution as a function of time.

MOPPC009	Multipactor for E-cloud Diagnostics	resonance, cyclotron, vacuum, dipole	139
	P. Costa Pinto, F. Caspers, P. Edwards, M. Holz, M. Taborelli CERN, Geneva, Switzerland
	Electron cloud in particle accelerators can be mitigated by coating the vacuum beam pipe with thin films of low secondary electron yield (SEY). SEY of small samples can be measured in the laboratory. Verifying the performance of long pipes is more complex, since it requires their insertion in the accelerator and the subsequent measurement of the beam induced pressure rise. RF induced multipacting in a coaxial waveguide configuration is proposed as a test before insertion in the machine. The technique is applied to two main bending dipoles of the SPS, where the RF power is fed though a tungsten wire stretched along the vacuum chamber (6.4 m). A dipole with a bare stainless steel chamber shows a clear power threshold initiating an abrupt rise in reflected power and pressure. The effect is enhanced at RF frequencies corresponding to cyclotron resonances for given magnetic field. Preliminary result show that the dipole with a carbon coated vacuum chamber does not exhibit any pressure rise or reflected RF power up to the maximum available input power. In the event of a large scale coating production this technique will be a valuable resource for quality control.

MOPPC019	Secondary Electron Yield Measurements of Fermilab’s Main Injector Vacuum Vessel	vacuum, gun, synchrotron, controls	166
	D.J. Scott, D. Capista, K.L. Duel, R.M. Zwaska Fermilab, Batavia, USA S. Greenwald, W. Hartung, Y. Li, T.P. Moore, M.A. Palmer CLASSE, Ithaca, New York, USA R.E. Kirby, M.T.F. Pivi, L. Wang SLAC, Menlo Park, California, USA
	We discuss the progress made on a new installation in Fermilab’s Main Injector that will help investigate the electron cloud phenomenon by making direct measurements of the secondary electron yield (SEY) of samples irradiated in the accelerator. In the Project X upgrade the Main Injector will have its beam intensity increased by a factor of three compared to current operations. This may result in the beam being subject to instabilities from the electron cloud. Measured SEY values can be used to further constrain simulations and aid our extrapolation to Project X intensities. The SEY test-stand, developed in conjunction with Cornell and SLAC, is capable of measuring the SEY from samples using an incident electron beam when the samples are biased at different voltages. We present the design and manufacture of the test-stand and the results of initial laboratory tests on samples prior to installation.

MOPPC026	Simulations of Coherent Beam-Beam Effects with Head-on Compensation	resonance, proton, simulation, lattice	187
	S.M. White, W. Fischer, Y. Luo BNL, Upton, Long Island, New York, USA
	Funding: Work partially supported by Brookhaven Science Associates, LARP, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Electron lenses are foreseen to be installed in RHIC in order to mitigate the head-on beam-beam effects. This would allow operation with higher bunch intensity and result in a significant increase in luminosity. We report on recent strong-strong simulations that were carried out using the RHIC upgrade parameters to assess the impact of coherent beam-beam effects in the presence of head-on compensation.

MOPPC036	Influence of Intense Beam in High Pressure Hydrogen Gas Filled RF Cavities	cavity, plasma, proton, pick-up	208
	K. Yonehara, M.R. Jana, M.A. Leonova, A. Moretti, M. Popovic, T.A. Schwarz, A.V. Tollestrup Fermilab, Batavia, USA M. Chung Handong Global University, Pohang, Republic of Korea M.G. Collura Politecnico di Torino, Torino, Italy G. Flanagan, R.P. Johnson, M. Notani Muons, Inc, Batavia, USA B.T. Freemire, Y. Torun IIT, Chicago, Illinois, USA
	Funding: This work is supported by US DOE under contract DE-AC02-07CH11359. Breakdown plasma in a high-pressure hydrogen gas filled RF cavity has been studied from a time domain spectroscopic light analysis. The observed breakdown plasma temperature and density reached 21,000 K and 10²⁰ cm^-3, respectively. The electron recombination rate has been evaluated from the decay of plasma density in various gas pressures. The recombination mechanism in dense plasma will be discussed. Finally, the similarity and difference of the breakdown processes between the high-pressure hydrogen gas filled RF cavity and a vacuum RF one will be discussed.

MOPPC037	Muon Collider Detector Backgrounds	collider, background, simulation, shielding	211
	M.A.C. Cummings, S.A. Kahn Muons, Inc, Batavia, USA D. Hedin Northern Illinois University, DeKalb, Illinois, USA J.F. Kozminski Lewis University, Romeoville, Illinois, USA
	Funding: Supported in part by SBIR Grant 4738 · 10SC05447 Technological innovations in recent years have revived interest in muon colliders as the next generation energy frontier machine. Advances in muon cooling technology will make the focussing and acceleration of muons to TeV energies possible. The biggest challenge for muon colliders is that muons decay, but it is possible to build a large muon collider as a circular machine, even at multi-TeV energies, due to the greatly reduced synchrotron radiation expected from muons compared to electrons. The challenge for the detectors in such machines is overcoming the large backgrounds from muon decays in the colliding ring lattice that will inundate the interaction region (IR) and will make triggering and data reconstruction a challenge. Developing simulation tools that can reliably model the environment of the muon collider IR will be critical to physics analyses. We will need to expand the capabilities of current programs and use them to benchmark and verify results against each other. In this paper we will discuss these processes and calculate the resulting particle fluxes into the detector volume.

MOPPC038	Bethe-Heitler Muon Background at a Muon Collider	collider, background, hadron, simulation	214
	S.A. Kahn, M.A.C. Cummings, T.J. Roberts Muons, Inc, Batavia, USA D. Hedin, A.O. Morris Northern Illinois University, DeKalb, Illinois, USA J.F. Kozminski Lewis University, Romeoville, Illinois, USA
	Multi-TeV muon colliders are an important option for a future energy frontier lepton collider since synchrotron radiation in a circular machine is significantly less than that in an electron collider. For a muon collider with 750 GeV μ+μ− with 2×10¹² μ per bunch we would expect 8.6×10⁵ muon decays per meter for the two beams. Muon decays are the source of beam induced backgrounds that can affect the physics. These backgrounds include electrons from muon decays, synchrotron radiation from the decay electrons, hadrons produced by photo-nuclear interactions, coherent and incoherent beam-beam pair production and Bethe-Heitler muon production. This paper will describe a simulation of the B-H muon pair production in a muon collider. These muons can penetrate the collider ring magnets and shielding and possibly enter into the detector regions. The simulation tracks B-H muons produced from electromagnetic shower interactions in collider ring material in the range of ±200 m from the interaction point.

MOPPC039	Electron Recombination in a Dense Hydrogen Plasma	cavity, collider, plasma, ion	217
	B.T. Freemire, P.M. Hanlet IIT, Chicago, Illinois, USA M. Chung Handong Global University, Pohang, Republic of Korea M.G. Collura Politecnico di Torino, Torino, Italy M.R. Jana, C. Johnstone, T. Kobilarcik, G.M. Koizumi, M.A. Leonova, A. Moretti, M. Popovic, T.A. Schwarz, A.V. Tollestrup, Y. Torun, K. Yonehara Fermilab, Batavia, USA R.P. Johnson Muons, Inc, Batavia, USA
	Funding: US DOE under contract DE-AC02-07CH11359. A high pressure hydrogen gas filled RF cavity was subjected to an intense proton beam to study the evolution of the beam induced plasma inside the cavity. The electron recombination rate with the dense ionized hydrogen plasma has been measured under varying conditions. Recombination rates as high as 10^-7 cm³/s have been recorded. This technique shows promise in the R&D program for a muon accelerator. The use of hydrogen, both as a way to prevent breakdown in an RF cavity and as a mechanism for cooling a beam of muons, will be discussed.

MOPPC040	Study of Electronegative Gas Effect in Beam-Induced Plasma	cavity, plasma, proton, ion	220
	M.A. Leonova, M.R. Jana, A. Moretti, M. Popovic, T.A. Schwarz, A.V. Tollestrup, K. Yonehara Fermilab, Batavia, USA M. Chung Handong Global University, Pohang, Republic of Korea M.G. Collura Politecnico di Torino, Torino, Italy B.T. Freemire, P.M. Hanlet, Y. Torun IIT, Chicago, Illinois, USA R.P. Johnson Muons, Inc, Batavia, USA
	Funding: This research was supported by US DOE under contract DE-AC02-07CH11359. Muon Colliders and Neutrino Factories call for R&D for a high-gradient RF system capable of operating in a high magnetic field. Adding a high pressure gas inside an RF cavity (HPRF) prevents cavity breakdown, allowing higher gradients in a magnetic field. A high-energy beam passing through an HPRF cavity ionizes the gas, producing plasma. Plasma electrons absorb cavity’s energy, reducing the energy available for beam acceleration. Doping cavity gas with electronegative gas (gas that tends to attract and bond electrons) reduces the number of plasma electrons. The experiments were carried out at the MuCool Test Area (MTA) facility at Fermilab. Different concentrations of an electronegative gas SF6 were added to hydrogen gas. The results of room-temperature tests showing a great reduction in power drop in the cavity will be presented. However, a realistic cavity would operate at liquid nitrogen temperature, where SF6 freezes. Thus, a search for a better electronegative gas candidate is underway; we plan to test oxygen-doping next.

MOPPC045	Scaled Electron Model of a Dogbone Muon RLA with Multi-pass Arcs	linac, quadrupole, dipole, optics	235
	S.A. Bogacz, A. Hutton, G.A. Krafft, V.S. Morozov, Y. Roblin JLAB, Newport News, Virginia, USA K.B. Beard, R.P. Johnson Muons, Inc, Batavia, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Supported in part by USDOE STTR Grant DE-FG02-08ER86351. The design of a dogbone RLA with linear-field multi-pass arcs was earlier developed for accelerating muons for a future Neutrino Factory and Muon Collider. It allows for efficient use of expensive RF while the multi-pass arc design based on linear combined-function magnets exhibits a number of advantages over single pass or pulsed arc designs. Such an RLA may have applications going beyond muon acceleration. This paper describes a possible straightforward test of this concept by scaling a GeV scale muon design for electrons. Scaling muon momenta by the muon-to-electron mass ratio leads to a scheme in which a 4.35 MeV/c electron beam is injected in the middle of a 2.9 MeV/pass linac with two double-pass return arcs, and is accelerated to 17.4 MeV/c in 4.5 passes. All spatial dimensions including the orbit distortion are scaled by a factor of 7.5, which arises from scaling the 200 MHz muon RF to a readily available 1.5 GHz. The footprint of a complete RLA fits in an area of 25 by 7 m. The scheme utilizes only fixed magnetic fields including injection and extraction. The hardware requirements are not very demanding, making it feasible to utilize the existing technologies. The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

MOPPC049	Status of the Non-scaling Fixed Field Alternating Gradient Ring Design for the International Design Study of the Neutrino Factory	factory, acceleration, septum, lattice	241
	J.S. Berg, H. Witte BNL, Upton, Long Island, New York, USA M. Aslaninejad, J. Pasternak Imperial College of Science and Technology, Department of Physics, London, United Kingdom N. Bliss, A.J. Moss STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom D.J. Kelliher, S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom S.M. Pattalwar STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The International Design Study of the Neutrino Factory is working towards delivering the optimized design of the neutrino factory facility to be presented in the Reference Design Report (RDR) in 2013. In the current baseline design a linear non-scaling fixed field alternating gradient accelerator (FFAG) was chosen as an efficient solution for the final muon acceleration. We describe updates to the design since our previous report. We report on beam dynamics studies on the lattice. We describe recent work on the engineering for the lattice, and the results of a recent first pass at a cost estimate for the machine. Finally, we describe how an FFAG may be applicable to a lower energy neutrino factory in light of recent experimental results regarding the value of the theta(13) neutrino mixing angle. J. S. Berg et al., in Proceedings of IPAC2011, San Sebastian, Spain, 832. ** F. P. An et al., Phys. Rev. Lett. 10⁸, 171803 (2012); J. K. Ahn et al., arXiv:1204.0626v2 [hep-ex] (2012).

MOPPC052	Calculation of Synchrotron Radiation from High Intensity Electron Beam at eRHIC	photon, radiation, synchrotron, vacuum	247
	Y.C. Jing, O.V. Chubar, V. Litvinenko BNL, Upton, Long Island, New York, USA
	The Electron-Relativistic Heavy Ion Collider (eRHIC) at Brookhaven National Lab adds an electron beam line to the existing RHIC and improves the luminosity by at least 2 orders of magnitude. It requires a high energy and high intensity electron beam. Thus the synchrotron radiation (SR) coming from the bending magnets and large quadrupoles could be penetrating the vacuum chamber and providing hazard to electronic devices and undesired background for detectors. In this paper, we calculate the SR spectral intensity and power density distributions on the chamber wall, suggest the wall thickness required to stop the SR, calculate heat load on the chamber, and estimate spectral characteristics of the residual and scattered background radiation outside the chamber.

MOPPC054	Multi-code Modelling of Momentum Collimation in the TRIUMF ARIEL Linac	gun, linac, simulation, TRIUMF	253
	F.W. Jones, Y.-C. Chao, C. Gong TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	The electron linac component of the TRIUMF-ARIEL facility will provide CW beams of 50-75 MeV and up to 0.5 MW of beam power, with consequent requirements for low-loss operation. One factor in controlling beam quality is the reduction of the low-momentum tail arising from the rf-modulated 300 KV electron gun and initial capture elements prior to acceleration in the 10 MeV Injector linac. To study momentum collimation in the 10 MeV transfer line to the main linac, and its implications for downstream beam characteristics, a simulation model has been constructed using several tracking and optics codes, linked together by scripts and data converters. The model follows the evolution of the beam from the e-gun through the injector cryo-module and the medium energy transfer line where the proposed collimator is located. The components, methods and results of this application are described in detail.

MOPPC060	Investigations into Beam Life Time in Low Energy Storage Rings	ion, target, storage-ring, antiproton	271
	A.I. Papash, A.V. Smirnov MPI-K, Heidelberg, Germany A.I. Papash JINR, Dubna, Moscow Region, Russia C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: Work supported by the Helmholtz Association of National Research Centers and GSI under contract VH-NG-328. In low energy storage rings, beam life time critically depends on the residual gas pressure, scattering effects caused by in-ring experiments and the available machine acceptance. A comprehensive simulation study into these effects has been realized with a focus on the TSR storage ring in Heidelberg and the electrostatic rings ELISA, the AD recycler and the ultra-low energy storage ring (USR). This was done by using the computer code BETACOOL in combination with the OPERA-3D and MAD-X programs. In this contribution, the results from these studies are presented and compared to available experimental data. Based on these simulations, criteria for stable ring operation are then presented.

MOPPC063	Computation of the 2D Transverse Wake Function of an Electron Cloud for Different Parameters	simulation, dipole, lattice, wakefield	280
	A. Markoviḱ, G. Pöplau, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
	Funding: Work supported by DFG under contract number RI 814/20-2. A PIC simulation of the interaction of a positive charged bunch with an e-cloud yields the wake kick from the electrons on the tail particles of the bunch. The wake is induced from a certain offset in the transverse position of the head parts of the bunch which perturb the electron distribution. Such a pre-computed wake functions of each offset part of the bunch are forming a matrix which could be used for investigating single bunch stability under several assumptions. In this paper we investigate the linear scalability of the kick with the offset value. Furthermore we investigate the wake values for different realistic electron densities. Another important parameter for realizing the single bunch stability simulation is the optimal number of bunch slices in longitudinal direction. Here we study the thickness of the slices in conjunction with the mobility of the electrons around the beam axis.

MOPPC064	Simulation of the Behavior of Ionized Residual Gas in the Field of Electrodes	ion, simulation, emittance, vacuum	283
	G. Pöplau, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany A. Meseck HZB, Berlin, Germany
	Funding: Work supported by BMBF under contract number 05K10HRC Light sources of the next generation such as ERLs require minimal beam losses as well as a stable beam position and emittance over the time. Instabilities caused by ionized residual gas have to be avoided. In this paper we present simulations of the behavior of ionized residual gas in the field of clearing electrodes and investigate e.g. clearing times. For these simulations we apply MOEVE PIC Tracking developed at Rostock University. We demonstrate numerical results with parameters planed for the ERL BERLinPro.

MOPPC066	A Design of Thermionic Electron Gun for Traveling Wave Electron-linac in order to Inject Beam into Booster Synchrotron Accelerator	gun, cathode, simulation, synchrotron	286
	S. Ahmadian, F. AbbasiDavani, F. Ghasemi, M.Sh. Shafiee sbu, Tehran, Iran
	Applying computational codes functioning on the basis of methods such as Finite Integration caused the designing of different parts of an accelerator to be done faster and with more precision. The first step in using new software is the validation of these codes by experimental results, analytic relations or validating them against other codes whose validity has already been proved. This research aims to design an appropriate structure for thermionic electron gun of traveling wave electron-linac to be used to inject beam into synchrotron accelerators. Firstly, a simple structure of an electron gun used in TWT tube was simulated, and the parameters such as current, perveance, waist beam position, waist beam radius, beam radius entering anode aperture, and also the electric potential variation in the anode-cathode distance and the electric field of anode aperture were compared by experimental results and analytic relations. After verifying the software accuracy, a design for an electron gun with energy and current respectively 200 keV, 18 A and also initial beam radius of 8mm and minimum beam radius of 2.4 mm situated at the distance of 67.44mm from the cathode, was presented.

MOPPC067	Design and Construction of Inductive BPM	simulation, impedance, vacuum, resonance	289
	M.Sh. Shafiee, E.E. Ebrahimibasabi, S.A.H. Feghhi, N. Goudarzi sbu, Tehran, Iran M. Jafarzadeh ILSF, Tehran, Iran
	To have a controllable Electron machine, that is required to be able to control beam orbits by knowing the beam position. The basic requirement for detecting the position of electron is calibrating and testing the BPMs. For this purpose wire method is used. Since we hadn't access to accelerator, for having experience at beam diagnostic we used this method for testing our constructed inductive BPM including 4 cm square poly ethylene core with 15 turns coil in each side. In this case study that was tested by a pulsed current (as an electron bunch) produced by a pulse generator. At first Tektronix 2235A oscilloscope was calibrated and used to measure the induced voltage of each coils, then by using of microcontroller, protocol RS232 and GUI induced voltages were read. The electrical center was measured with respect to the mechanical center and wire position was detected with 1mm Resolution. Conversion between the BPM signals and the actual wire position were done. Results were compared and presented.

MOPPC070	Field Emission Simulation for KEK-ERL 9-Cell Superconducting Cavity	cavity, simulation, linac, coupling	295
	E. Cenni Sokendai, Ibaraki, Japan T. Furuya, H. Sakai, M. Satoh, K. Shinoe, K. Umemori KEK, Ibaraki, Japan M. Sawamura JAEA/ERL, Ibaraki, Japan
	In order to develop the Energy Recovery Linac at KEK, we are studying the performance of L-band superconducting cavities by means of vertical tests. One of the limiting factor for the cavities performance is power losses due to field emitted electrons. With regard to this phenomena, a particle tracking code is used to study electron trajectories and deposited energy on the inner surface of the cavity. Different emitters location were tested within a range of accelerating field and phases in order to reproduce different scenario. The final goal of this study is to locate the sources of the electrons inside the cavity through a deeper understanding of the phenomena. To validate the results from the simulation the outcome data are compared with other particle tracking codes.

MOPPC075	A Generic Data Model for HeadTail: Design and Implementation with Examples	simulation, HOM, wakefield, collective-effects	307
	K.S.B. Li, G. Rumolo CERN, Geneva, Switzerland
	HeadTail has been developed in 2002 for the efficient simulation of instabilities and collective effects in large circular accelerators. Since then, the capabilities of the code have been continuously extended and the output data has become increasingly complex and large-scale ranging from the statistical description of single bunches to the statistical description of all slices within bunches up to the dynamics of the full 6D phase space over several thousands of turns. Processing this data in an effective manner and endowing it with a structure that provides a physical concept calls for new and optimised data formats. To meet state-of-the-art standards, the hierarchical data format (HDF5) has been selected as native output data format together with H5Part and XDMF as native data structures. We describe the implementation of the H5Part and the XDMF data structures into HeadTail and show some illustrative examples for data processing.

MOPPC079	Modelling of the EMMA ns-FFAG Ring Using GPT	space-charge, emittance, injection, quadrupole	319
	R.T.P. D'Arcy, S. Jolly UCL, London, United Kingdom J.K. Jones, B.D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom S.B. van der Geer Pulsar Physics, Eindhoven, The Netherlands
	EMMA (Electron Machine with Many Applications) is a prototype non-scaling Fixed-Field Alternating Gradient (ns-FFAG) accelerator whose construction at Daresbury Laboratory, UK, was completed in the autumn of 2010. The energy recovery linac ALICE will serve as an injector for EMMA, within an energy range of 10 to 20 MeV. The injection line consists of a symmetric 30 degree dogleg to extract the beam from ALICE, a matching section and a tomography section for transverse emittance measurements. This is followed by a transport section to the injection point of the EMMA ring. The ring is composed of 42 cells, each containing one focusing and one defocusing quadrupole. Acceleration over many turns of the EMMA machine has recently been confirmed. In some cases the bunch will traverse upwards of 100 turns, at which point the effects of space-charge may be significant. It is therefore necessary to model the electron beam transport in the ring using a code capable of both calculating the effect of and compensating for space-charge. Therefore the General Particle Tracer (GPT) code has been used. A range of injection beam parameters have been modeled for comparison with experimental results.

MOPPC081	Simulation of RF Cavity Dark Current in Presence of Helical Magnetic Field	cavity, simulation, dipole, site	325
	G.V. Romanov, V.S. Kashikhin Fermilab, Batavia, USA
	In order to produce muon beam of high enough quality to be used for a Muon Collider, its large phase space must be cooled several orders of magnitude. This task can be accomplished by ionization cooling. Ionization cooling consists of passing a high-emittance muon beam alternately through regions of low-Z material, such as liquid hydrogen, and very high accelerating RF cavities within a multi-Tesla solenoidal focusing channel. But first high power tests of an RF cavity with beryllium windows in a solenoidal magnetic field showed a dramatic drop in accelerating gradient due to RF breakdowns. It has been concluded that external magnetic fields parallel to the RF electric field significantly modifies the performance of RF cavities. However, the magnetic field in a Helical Cooling Channel has a strong dipole component in addition to a solenoidal one. The dipole component essentially changes electron motion in a cavity compared to a pure solenoidal case, making dark current less focused at field emission sites. The simulation of a dark current dynamic in HCC performed with CST Studio Suite is presented in this paper.

MOPPC084	G4beamline Code Development	space-charge, collider, radiation, synchrotron	334
	T.J. Roberts Muons, Inc, Batavia, USA
	Funding: Supported in part by DoE STTR grant DE-FG02-06ER86281. G4beamline is a single-particle-tracking simulation program based on Geant4, optimized specifically for beam lines. It is currently used by several hundred physicists and designers around the world, who apply it to a diverse set of interesting problems. As it includes particle decays and interactions, it is applicable to beams for which decays and interactions are important, such as modern muon facilities that involve ionization cooling. Its description language has been designed to be both versatile and user-friendly, and the program includes high-quality visualization and histogramming capabilities. This paper discusses recent code development and new features, and some interesting applications of the program. G4beamline is an open-source program freely available at http://g4beamline.muonsinc.com

MOPPC090	Coupling Modulator Simulations into an FEL Amplifier for Coherent Electron Cooling	FEL, simulation, radiation, positron	346
	I.V. Pogorelov, G.I. Bell, D.L. Bruhwiler, B.T. Schwartz, S.D. Webb Tech-X, Boulder, Colorado, USA Y. Hao, V. Litvinenko, G. Wang BNL, Upton, Long Island, New York, USA
	Funding: Work supported by the US DOE Office of Science, Office of Nuclear Physics under grant numbers DE-FG02-08ER85182 and DE-SC0000835. Next-generation ion colliders will require effective cooling of high-energy hadron beams. Coherent electron cooling (CeC) can in principle cool relativistic hadron beams on orders-of-magnitude shorter time scales than other techniques. Particle-in-cell (PIC) simulations of a CeC modulator with the parallel VORPAL framework generate macro-particle distributions with subtle but important phase space correlations. To couple these macro-particles into a 3D simulation code for the free-electron laser (FEL) amplifier, while retaining all details of the 6D phase space coordinates, we implemented an alternative approach based on particle-clone pairs. Our approach allows for self-consistent treatment of shot noise and spontaneous radiation, with no need for quiet-start initialization of the FEL macro-particles' ponderomotive phase. We present results of comparing fully 3D amplifier modeling based on the particle-clone approach vs GENESIS simulations where distribution of bunching parameter was used as input. We also discuss enabling direct coupling of the VORPAL delta-f simulation output into 3D distributions of particle-clone pairs. V.N. Litvinenko and Y.S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009). ** V.N. Litvinenko, "Macro-particle FEL model with self-consistent spontaneous radiation," unpublished (2002).

MOPPC093	Optimal Fast Multipole Method Data Structures	target, multipole, simulation, space-charge	352
	S. Abeyratne, B. Erdelyi Northern Illinois University, DeKalb, Illinois, USA S.L. Manikonda ANL, Argonne, USA
	The Fast Multipole Method (FMM) has been identified as one of the ten most significant numerical algorithms discovered in the 20th century. The FMM guarantees finding fast solutions to many problems in science, such as calculating Coulomb potentials among large number of particles by reducing memory footprint and run time while attaining very high accuracy levels. One important practical issue that we have to solve in implementing a FMM algorithm is organizing large amounts of data, also called data structuring. The non-adaptive FMM is appropriate when the particles are uniformly distributed while the adaptive FMM is most efficient when the distribution is non-uniform. In practice, we typically encounter highly non-uniform 3D particle distributions. This paper summarizes our implementation of a 3D adaptive FMM algorithm data structure setup for non-uniform particle distributions.

MOPPC094	Charge Density Estimations with Orthogonal Polynomials	space-charge	355
	D. Hernandez, B. Erdelyi Northern Illinois University, DeKalb, Illinois, USA
	Funding: This work was supported by the Department of Energy under Contract No. DE-FG02-08ER41532 with Northern Illinois University. A beam’s charge density, treated as a smooth and continuous function can be approximated using orthogonal series, allowing a solution of Poisson’s equation to be found. Getting the most accurate solution to the electric potential requires the best approximated charge density. Several beam distributions are approximated using Jacobi polynomials generated by the recursion relation and the moment method. Varying both the particle number and order of the approximation gives a chance to not only compare the performance of the different polynomials, but allows to determine if a particular combination of order and particle number works better for a particular function. Although all three orthogonal polynomials used give similar results, the approximation coefficients should be allowed to converge and taken to high orders for best results. This is clearly seen on the single Gaussian approximation, where after five million particles, the difference between the distributions remains constant and the highest tested order gives best results.

MOPPD006	Commissioning of the 2MeV Electron Cooler for COSY / HESR	high-voltage, solenoid, gun, laser	379
	V. Kamerdzhiev, J. Dietrich FZJ, Jülich, Germany V.N. Bocharov, M.I. Bryzgunov, A.D. Goncharov, V.M. Panasyuk, V.V. Parkhomchuk, V.B. Reva, D.N. Skorobogatov BINP SB RAS, Novosibirsk, Russia
	The new electron cooler for COSY is built at BINP Novosibirsk. Electron beam commissioning is in progress. Installation in COSY and commissioning with proton beam is scheduled for the beginning of 2012. Beam cooling with up to 3 A of electron current at up to 2 MeV is expected to boost the luminosity in the entire energy range of COSY by counteracting the effects caused by dense targets interacting with the circulating beam. Furthermore, the 2 MeV electron cooler can be used for beam cooling at injection energy in the HESR ring in the FAIR project. The electron beam is guided by a solenoidal magnetic field all the way from the electron gun to the collector. A cascade transformer provides power to numerous high voltage sections, short solenoids, and the collector inside a pressure vessel filed with SF6 gas. Commissioning results are reported.

MOPPD007	Towards Routine Operation of the Scintillation Profile Monitor at COSY	vacuum, injection, synchrotron, proton	382
	V. Kamerdzhiev, J. Dietrich, K. Reimers FZJ, Jülich, Germany C. Böhme ESS, Lund, Sweden A. Pernizki INP, Jülich, Germany
	The optics of the Scintillation Profile Monitor (SPM) was modified to correct the large error observed in previous measurements. Beam profile measurements were carried out after reinstallation in the COSY ring, showing reasonable agreement with profiles, measured with the ionization profile monitor. Performance of the SPM is analyzed. Application of the method in a proton synchrotron is discussed.

MOPPD016	Status of Proof-of-principle Experiment for Coherent Electron Cooling	gun, ion, wiggler, FEL	400
	I. Pinayev, S.A. Belomestnykh, I. Ben-Zvi, J. Bengtsson, A. Elizarov, A.V. Fedotov, D.M. Gassner, Y. Hao, D. Kayran, V. Litvinenko, G.J. Mahler, W. Meng, T. Roser, B. Sheehy, R. Than, J.E. Tuozzolo, G. Wang, S.D. Webb, V. Yakimenko BNL, Upton, Long Island, New York, USA G.I. Bell, D.L. Bruhwiler, V.H. Ranjbar, B.T. Schwartz Tech-X, Boulder, Colorado, USA A. Hutton, G.A. Krafft, M. Poelker, R.A. Rimmer JLAB, Newport News, Virginia, USA M.A. Kholopov, P. Vobly BINP SB RAS, Novosibirsk, Russia
	Funding: US DOE Office of Science, DE-FC02-07ER41499, DE-FG02-08ER85182; NERSC DOE contract No. DE-AC02-05CH11231. Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron colliders. To verify the concept we conduct proof-of-the-principle experiment at RHIC. In this paper, we describe the current experimental setup to be installed into 2 o’clock RHIC interaction regions. We present current design, status of equipment acquisition and estimates for the expected beam parameters.

MOPPD029	Recent Achievements and Upgrade Programs at RIKEN Radioactive Isotope Beam Factory	ion, cyclotron, ECRIS, linac	430
	H. Okuno, T. Dantsuka, M. Fujimaki, T. Fujinawa, N. Fukunishi, H. Hasebe, Y. Higurashi, K. Ikegami, E. Ikezawa, H. Imao, T. Kageyama, O. Kamigaito, M. Kase, M. Kidera, M. Komiyama, H. Kuboki, K. Kumagai, T. Maie, M. Nagase, T. Nakagawa, M. Nakamura, J. Ohnishi, N. Sakamoto, K. Suda, H. Watanabe, T. Watanabe, Y. Watanabe, K. Yamada, H. Yamasawa RIKEN Nishina Center, Wako, Japan
	Recent achievements and upgrade programs in the near future at RIKEN Radioactive Isotope Beam Factory (RIBF) are presented. The beam intensity and available ion species are increasing at RIBF, owing to the continuous efforts that have been paid since the first beam in 2006. So far, we accelerated deuteron, helium, nitrogen, oxygen, aluminum, calcium, krypton, and uranium beams with the world's first superconducting ring cyclotron, SRC. The extracted beam intensities reached 1,000 pnA for helium and oxygen beams. From the operational point of view, however, the intensity of the uranium beam should be much increased. Therefore we constructed a new injector system for the RIBF, consisting of a 28 GHz ECR ion sources, RFQ and DTL, which was successfully commissioned in the end of 2010. Furthermore we developed low-Z (low atomic number Z) gas stripper* alternative to standard carbon foil stripping, which will be reliable and efficient charge stripping scheme for such high-power uranium beams. * H. Okuno et al., IEEE Trans. Appl. Supercond., 18, 226 (2008). ** H. Okuno et al., Phys. Rev. ST Accel. Beams 14, 033503 (2011).

MOPPD038	Simulation Study of Electron Response Amplification in Coherent Electron Cooling	ion, bunching, FEL, undulator	448
	Y. Hao, V. Litvinenko BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. In Coherent Electron Cooling (CEC), it is essential to study the amplification of electron response to a single ion in the FEL process, in order to proper align the electron beam and the ion beam in the kicker to maximize the cooling effect. In this paper, we use Genesis to simulate the amplified electron beam response of single ion in FEL amplification process, which acts as 'Green function' of the FEL amplifier.

MOPPD043	Novel Muon Beam Facilities for Project X at Fermilab	proton, target, dipole, linac	457
	C.M. Ankenbrandt, R.J. Abrams, T.J. Roberts, C. Y. Yoshikawa Muons, Inc, Batavia, USA D.V. Neuffer Fermilab, Batavia, USA
	Innovative muon beam concepts for intensity-frontier experiments such as muon-to-electron conversion are described. Elaborating upon a previous single-beam idea, we have developed a design concept for a system to generate four high quality, low-energy muon beams (two of each sign) from a single beam of protons. As a first step, the production of pions by 1 and 3 GeV protons from the proposed Project X linac at Fermilab is being simulated and compared with the 8-GeV results from the previous study.

MOPPD046	Lifetime of the Highly Efficient H⁻ Ion Sources	cathode, ion, plasma, extraction	466
	V.G. Dudnikov Muons, Inc, Batavia, USA D.S. Bollinger Fermilab, Batavia, USA D.C. Faircloth, S.R. Lawrie STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	Funding: Work supported by grant DE-SC0006267, and STFC JAI grant ST/G008531 Factors limiting operating lifetime of Compact Surface Plasma Sources (CSPS) are analyzed and possible treatments for lifetime enhancement are considered. CSPSs have high plasma density (up to 10¹⁴ cm^-3), high emission current density of negative ions (up to 8 A/cm²), small (1–5 mm) gap between cathode emitter, and a small extraction aperture in the anode. They are very simple, have high energy efficiency up to 100 mA/kW of discharge (~100 times higher then modern large Volume RF SPS) and have a high gas efficiency (up to 30%) using pulsed valves. CSPSs are very good for pulsed operation but electrode power density is often too high for dc operation. However, CSPSs were successfully adopted for DC operation with emission current density ~300 mA/cm² in Hollow cathode Penning Discharge and up to 1 A/cm² in Spherical focusing semiplanotron. Flakes from electrodes sputtering and blistering induced by back accelerated positive ions are the main reasons of ion source failure. Suppression of back accelerated positive ions, flakes explosion by pulsed discharges, and flakes gasification by discharge in NF₃ (or XeF₂) can be used for significant increase of operating lifetime of CSPSs.

MOPPD047	Progress of Surface Plasma H⁻ Ion Source with Saddle RF Antenna Plasma Generator	plasma, ion, ion-source, gun	469
	V.G. Dudnikov, R.P. Johnson Muons, Inc, Batavia, USA S.N. Murray, T.R. Pennisi, C. Piller, M. Santana, M.P. Stockli, R.F. Welton ORNL, Oak Ridge, Tennessee, USA
	Funding: Supported in part by SBIR Grant 4729 · 09SC02690. Progress in development of RF H⁻ surface plasma source (SPS) with saddle (SA) RF antenna which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability will be considered. Several versions of new plasma generators with a small Al2O3chamber and different antennas and magnetic field configurations were tested in the SNS small Test Stand. A prototype SA SPS was installed in the Test Stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency of 1.6 mA/kW. Control experiments with H⁻ beam produced by SNS SPS with internal and external antennas in the similar conditions were conducted. A new version of the RF triggering plasma source (TPS) has been designed and fabricated. A Saddle antenna SPS with water cooling is being fabricated for high duty factor testing

MOPPD048	Ribbon Electron Beam Profile Monitor for Bunched Beam Tomography	cathode, proton, ion, diagnostics	472
	V.G. Dudnikov Muons, Inc, Batavia, USA A.V. Aleksandrov ORNL, Oak Ridge, Tennessee, USA
	Funding: Work supported by Contract DE-AC05-00OR22725 and by STTR grant DE-SC0007559 Advanced beam diagnostics are essential for high performance accelerator beam production and for reliable accelerator operation. It is important to have noninvasive diagnostics which can be used continuously with intense beams of accelerated particles. Recently, an electron probe was successfully used to determine accelerated particle density distributions. However, the apparatus used for this diagnostic is large and complex which restricts its wider use for tomography of accelerated bunches. We propose to use a strip cathode is for ribbon electron beam formation instead of a scanning of pencil beam used in the previous electron probe bunch profile monitors. The apparatus with the strip cathode is smaller, has simpler design and less expensive manufacturing, can have better magnetic shielding, higher sensitivity, higher resolution, can have better measurement accuracy and better time resolution. With this device it is possible to develop almost ideal tomography diagnostics of bunches in linear accelerators and in circular accelerators and storage rings.

MOPPD063	A 180 MeV Injection System for the ISIS Synchrotron	injection, dipole, synchrotron, simulation	511
	B. Jones, D.J. Adams, M.C. Hughes, S.J.S. Jago, H. V. Smith, C.M. Warsop, R.E. Williamson STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
	The ISIS Facility at the Rutherford Appleton Laboratory in the UK produces intense neutron and muon beams for condensed matter research. It operates at 50 Hz accelerating 3x10¹³ protons per pulse via a 70 MeV H⁻ linac and an 800 MeV proton synchrotron, delivering a mean beam power of 0.2 MW. A favoured first step to upgrade ISIS towards the megawatt regime is replacement of the linac with a new 180 MeV injector. Studies of this upgrade, which aims to increase mean beam power up to 0.5 MW are continuing. This paper summarises designs for a new injection region including beam dynamics and related hardware.

MOPPD069	Challenges for the SNS Ring Energy Upgrade	injection, kicker, septum, extraction	520
	M.A. Plum, T.V. Gorlov, J.A. Holmes, T. Hunter, R.T. Roseberry, J. G. Wang ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. The Oak Ridge Spallation Neutron Source accumulator ring presently operates at a beam power of about 1 MW and a beam energy of 925 MeV. A power upgrade is planned to increase the beam energy to 1.3 GeV. For the accumulator ring this mostly involves modifications to the injection and extraction sections. A variety of modifications to the existing injection section were necessary to achieve 1 MW, and the tools developed and the lessons learned from this work are now being applied to the design of the new injection section. This paper will discuss the tools and the lessons learned, and also present the design and status of the upgrades to the accumulator ring.

MOPPD073	Development of Transportation System for Low Energy Electron Group	solenoid, collimation, simulation, injection	532
	S. Kato Tohoku University, Graduate School of Science, Sendai, Japan M. Kinsho, K. Yamamoto, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	There is a time that we want to measure the electron which occurred in the accelerator in the small situation of a noise. In that case, it is one method that we transport these electrons to the place distant form the accelerator where a noise is small. In order to realize that, development of transport line for low energy electrons is required. So, we start to develop transport line using solenoid magnets. We present status of development of this transportation system.

MOPPP003	Comparison of Various Sources of Coherent THz Radiation at FLUTE	radiation, synchrotron, linac, synchrotron-radiation	568
	M. Schwarz, E. Huttel, A.-S. Müller, S. Naknaimueang, M.J. Nasse, R. Rossmanith, M. Schuh, P. Wesolowski KIT, Karlsruhe, Germany M.T. Schmelling MPI-K, Heidelberg, Germany
	The "Ferninfrarot Linac- Und Test-Experiment" FLUTE, based on a 50 MeV S-band linac with bunch compressor, is currently under construction at the KIT in Karlsruhe in order to study the production of coherent radiation in the Terahertz frequency range. The three photon generating mechanisms investigated in this paper are coherent synchrotron-, edge-, and transition radiation. For each case, we present the spectra and peak electric fields calculated from longitudinal charge distributions of a short, low charge and a long, high charge bunch. The respective bunch shapes are obtained by a detailed simulation (particle tracking) of FLUTE. We also give the expected temporal evolution of the electric field pulses.

MOPPP004	Further Study on Fast Cooling in Compton Storage Rings	laser, storage-ring, simulation, photon	571
	E.V. Bulyak NSC/KIPT, Kharkov, Ukraine J. Urakawa KEK, Ibaraki, Japan F. Zimmermann CERN, Geneva, Switzerland
	Compton sources can produce gamma-ray photons of ultimate intensity, but suffer from the large recoils experienced by the circulating electrons scattering off the laser photons. We have previously proposed a scheme called asymmetric fast cooling to reduce the beam energy spread in Compton rings. This report presents results of further studies on the fast cooling. In particular, we show that (1) a proper asymmetric setup of the scattering point results in significant reduction of the quantum losses of electrons in Compton rings with moderate energy acceptance, and (2) the optimized pulsed mode of operation in synchrotron-dominated rings enhances the overall performance of such gamma-ray sources. Theoretical results presented are in good accordance with numerical simulations. We discuss the performance of an existing storage ring such as KEK ATF DR equipped with an optical cavity and presently available laser system.

MOPPP005	Feasibility of THz Source Based on Coherent Smith-Purcell Radiation Generated by Femtosecond Electron Bunches in Super-Radiant Regime	radiation, simulation, laser, gun	574
	L.G. Sukhikh, K.P. Artyomov, A. Potylitsyn Tomsk Polytechnic University, Tomsk, Russia A.S. Aryshev, J. Urakawa KEK, Ibaraki, Japan V. Karataev JAI, Egham, Surrey, United Kingdom
	Nowadays there is a big interest to THz radiation that is a promising tool for investigations in material science, in biology, medicine and other fields. THz radiation for users is mostly produced by Light Sources that are big and complex machines. Because of this there are numerous activities in research and development of a compact THz source. One of the trends is based on using different types of radiation generated in coherent regime by short electron bunches. The promising radiation mechanism is coherent Smith-Purcell radiation (CSPR) that has monochromatic angular distribution and that is generated while the bunch travels in a vicinity of a grating. In this report we present simulated characteristics of frequency-locked coherent Smith-Purcell radiation (super-radiant regime) generated by a train of short (hundreds of femtosecond) 10 MeV electron bunches with THz spacing. The simulations are performed for different grating profiles and parameters using existing CSPR models and Particle-in-Cell simulation code. We also discuss the feasibility of the THz source based on CSPR and status of the experiment that is prepared at LUCX facility at KEK after the upgrade.

MOPPP006	Inverse Cherenkov Radiation based on Smith-Purcell Effect	radiation, linac, gun, laser	577
	K. Kan, T. Kondoh, K. Norizawa, A. Ogata, J. Yang, Y. Yoshida ISIR, Osaka, Japan M. Hangyo ILE Osaka, Suita, Japan R. Kuroda, H. Toyokawa AIST, Tsukuba, Ibaraki, Japan
	Inverse Cherenkov radiation based on Smith-Purcell effect using metamaterial was investigated. A metallic grating and picosecond electron bunch of 27 MeV beam energy from a thermionic DC gun and linac were used for the inverse radiation. The frequency spectra in terahertz (THz) range were measured by a Michelson interferometer experimentally. Peaks of discrete component in the spectra shifted continuously according to the radiation angles, e. g. discrete peak changing from 0.117 to 0.085 THz with radiation angle along the electron bunch from 102 to 134 degree (backward) using a 2-mm-period metallic grating. In this presentation, experiment using another electron bunch generated by a photocathode RF gun linac will be reported.

MOPPP007	High-intensity Monochromatic Cherenkov Radiation in THz Range by Femtosecond Electron Bunches in Impurity-doped Semiconductor Tube	radiation, plasma, wakefield, vacuum	580
	A. Ogata, K. Kan, T. Kondoh, K. Norizawa, J. Yang, Y. Yoshida ISIR, Osaka, Japan
	A novel method to generate high-power THz radiation is proposed and the preliminary experiments are conducted. If a beam with a bunch length on the order of 100 fs is injected into an electron–hole plasma of a semiconductor with a plasma frequency on the order of THz, THz wake fields are coherently generated. If the beam moves on the axis of a hollow tube covered by a metal, the frequency spectrum of the radiation is composed of discrete components. Monochromatic radiation is obtained by making only the lowest frequency component coherent. In the preliminary experiments using mm-sized dielectric tubes, the radiation spectra, which was driven by electron bunches of 200fs/27 MeV, were measured directly by a Michelson interferometer and bolometer. Peaks at frequencies of 0.09 and 0.14 THz of transverse magnetic (TM) modes, which corresponded to TM03 and TM04, were observed. The other higher modes, e. g. 0.36 (TM09) and 0.40 THz (TM010), were also observed successfully at a bunch charge of 15 pC, which decreased the electron bunch length.

MOPPP008	Hard X-ray Generation Experiment at Tsinghua Thomson Scattering X-Ray Source	laser, photon, scattering, background	583
	Y.-C. Du, H. Chen, Q. Du, Hua, J.F. Hua, W.-H. Huang, H.J. Qian, C.-X. Tang, H.S. Xu, L.X. Yan, Z. Zhang TUB, Beijing, People's Republic of China
	Recently, there is increasing industrial and scientific interesting in ultra-fast, high peak brightness, tunable energy and polarization, monochromatic hard X-ray source. The X-ray source based on the Thomson scattering between the relativistic electron beam and TW laser pulse is the suitable candidate for its compact and affordable alternatives for high brightness hard monochromatic X-ray generation. Accelerator laboratory in Tsinghua University al so proposed and built Tsinghua Thomson scattering X-ray source. The hard x-ray pulse has been generated in experiment with 47 MeV electron and 20 TW laser in this year, and the parameters of the X-ray have been measured preliminarily. The experimental results are presented and discussed in this paper.

MOPPP010	Investigation of CSR Effect for Femtosecond Electron Bunches in an Isochronous Accumulator Ring	simulation, lattice, radiation, linac	589
	N.Y. Huang, H. Hama, F. Hinode, S. Kashiwagi, M. Kawai, T. Muto, I. Nagasawa, K. Nanbu, Y. Shibasaki, K. Takahashi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	Coherent synchrotron radiation (CSR) from a novel isochronous ring is a candidate for light source that provides THz radiation with high average flux. A compact isochronous accumulator ring (IAR) for the maximum beam energy of 54 MeV has been designed so as to eliminate the 0th order momentum compaction factor, and the 1st order of it is mostly compensated. In addition, the path length deviation due to betatron motion is mostly compensated in a cell. Though there is no RF cavity in IAR, the injected beam may circulate for certain number of turns. Multi experimental stations can be allocated like synchrotron radiation facilities. However, it has been well known that instability due to the CSR wake field is an issue for the beam stability in the ring operated at low alpha mode. Therefore, a study for effects of the CSR wake on the bunch length and shape in IAR has been in progress. It has turned out that the maximum longitudinal field strength created by CSR would be ~ 0.15 MV/m for the case of 100 fs Gaussian bunch, which is considerably an intense field. To protect the bunch shape from the CSR wake, further study is definitely required.

MOPPP011	Narrow Band Optimization of a Compton Gamma-Ray Source Produced From an X-Band Linac	laser, simulation, emittance, linac	592
	F. Albert, S.G. Anderson, C.P.J. Barty, D.J. Gibson, F.V. Hartemann, R.A. Marsh, S.S.Q. Wu LLNL, Livermore, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Nuclear photonics is an emerging field of research that will require high precision gamma-ray (MeV) sources. In particular, nuclear resonance fluorescence applications necessitate a low (< 1%) relative gamma-ray spectral width. Within this context, Compton scattering, where laser photons are scattered off relativistic electron beams to produce tunable, collimated gamma rays, will produce the desired gamma-ray output. This paper will present the spectral narrowband optimization of such a light source currently being built at LLNL. In this case, PARMELA and elegant simulations of the full 250 MeV, high-gradient X-band linac provide the properties of the high brightness electron bunch. The electron beam simulations are then implemented into our newly developed weakly nonlinear Compton scattering code to produce theoretical gamma-ray spectra. The influence that the electron beam, laser beam and interaction geometry parameters have on the produced gamma-ray spectra will be shown with our simulations.

MOPPP013	Passive Momentum Spread Compensation by a “Wakefield Silencer”	wakefield, dipole, simulation, FEL	598
	S.P. Antipov, C.-J. Jing, A. Kanareykin, P. Schoessow Euclid TechLabs, LLC, Solon, Ohio, USA M.G. Fedurin, K. Kusche, V. Yakimenko BNL, Upton, Long Island, New York, USA W. Gai, A. Zholents ANL, Argonne, USA
	Funding: DOE SBIR. We report an observation of de-chirping of a linearly chirped (in energy) electron bunch by its passage through a 5 cm long dielectric loaded waveguide structure. The experiment was conducted at the ATF facility at BNL according to a concept dubbed a wakefield silencer originally developed at the ANL AATF, which involves defining the electron bunch peak current distribution and selecting the optimal waveguide structure suitable for chirp cancellation using self-induced wakefields of the electron bunch. Our experiment has been carried out with a 247 micron triangular beam with a 200 keV energy spread, which was reduced by a factor of three to approximately 70 keV by passing it through a 0.95 THz dielectric-lined structure. Theoretical analysis supports the experimental results. Further exploration and applications of this technique will be discussed as well. M. Rosing, J. Simpson, Argonne Wakefield Accelerator Note, WF -144 (1990).

MOPPP023	Effect of DC Photoinjector Gun Voltage on Beam Dynamics in ALICE ERL	gun, booster, linac, cavity	616
	Y.M. Saveliev, F. Jackson, J.K. Jones, J.W. McKenzie STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The ALICE ERL employs a DC HV photoelectron gun as an electron source. As with other machines in this class, the electron beam is not always of perfect quality. This is aggravated by that the ALICE gun has been operated so far at lower 230kV voltage compared to the design value of 350kV due to hardware limitations. The “two beams” structure was observed and experimentally investigated and found to be the result of complex processes during initial stages of beam acceleration. The experimental observations and data will be compared with those obtained at a nominal 350kV gun voltage. An investigation of the effect of the DC photogun voltage on longitudinal and transverse beam dynamics will be presented and discussed.

MOPPP028	SRF Photoinjector for Proof-of-principle Experiment of Coherent Electron Cooling at RHIC	SRF, gun, emittance, FEL	622
	D. Kayran, S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, X. Liang, G.T. McIntyre, I. Pinayev, B. Sheehy, J. Skaritka, T. Srinivasan-Rao, R. Than, J.E. Tuozzolo, Q. Wu, T. Xin BNL, Upton, Long Island, New York, USA V. Litvinenko, M. Ruiz-Osés Stony Brook University, Stony Brook, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy and by Stony Brook DOE grant DE-SC0005713. Coherent Electron Cooling (CEC) based on FEL amplifier promises to be a very good way to cool protons and ions at high energies. A proof of principle experiment to demonstrate cooling at 40 GeV/u is under construction at BNL. One of possible sources to provide sufficient quality electron beam for this experiment is a SRF photoinjector. In this paper we discuss design and simulated performance of the photoinjector based on existing 112 MHz SRF gun and newly designed single-cavity SRF linac operating at 704 MHz.

MOPPP029	Photocathodes at FLASH	cathode, photon, gun, laser	625
	S. Lederer, H. Hansen, H.-H. Sahling, S. Schreiber DESY, Hamburg, Germany P. Michelato, L. Monaco, D. Sertore INFN/LASA, Segrate (MI), Italy
	For several years, cesium telluride photocathodes have been successfully used in the photoinjector of the Free-Electron-Laser FLASH at DESY, Germany. They show a high quantum efficiency and long lifetime and produce routinely thousands of bunches per second with a single bunch charge mostly in the range of 0.3 to 1 nC. Recent studies on lifetime, quantum efficiency, dark current, and operating experience is reported. At DESY, a new preparation system has been set-up. First cathodes have been produced and tested.

MOPPP031	A New Injection System for an Electron/Positron Linac	linac, injection, gun, positron	628
	C. Liebig, M. Hüning, M. Schmitz DESY, Hamburg, Germany
	For the Linac II, which supplies the accelerator chain at DESY with electrons and positrons, a new injection system is planned. It is supposed to ensure reliable operation and to avoid the beam loss of about 60% before the positron converter and the associated activation. The main components are a 6 A/100 kV triode gun, buncher and a dispersive section for energy collimation. The output energy is 5 MeV. The new buncher structure is a hybrid of a standing wave and traveling wave structure and allows a compact design and good electron capture. Its main part is a traveling wave structure in 2π/3 mode, to which one capture cell is coupled in π mode. The function of the injector components, the entire injection system and the acceleration in the linac sections were optimized in simulations. In addition, the design is analysed in a test rig before final installation. Test rig and subsequent injector are equipped with extensive diagnostics. Besides the design of the injection system results of simulations and measurements on the test rig will be presented.

MOPPP032	Longitudinal Phase Space Studies at the PITZ Facility	laser, radiation, gun, FEL	631
	M. Mahgoub, J.W. Bähr, H.-J. Grabosch, M. Groß, L. Hakobyan, G. Klemz, G. Kourkafas, M. Krasilnikov, D. Malyutin, A. Oppelt, M. Otevřel, B. Petrosyan, K. Rosbach, F. Stephan, G. Vashchenko DESY Zeuthen, Zeuthen, Germany I.I. Isaev MEPhI, Moscow, Russia Ye. Ivanisenko IERT, Kharkov, Ukraine M. Khojoyan ANSL, Yerevan, Armenia J. Li USTC/NSRL, Hefei, Anhui, People's Republic of China B. Marchetti INFN-Roma II, Roma, Italy D. Richter HZB, Berlin, Germany J. Rönsch-Schulenburg Uni HH, Hamburg, Germany
	Photoinjectors are a cornerstone for short-wavelength Free Electron Lasers (FELs) like FLASH and the European XFEL in Hamburg, Germany. The Photo Injector Test facility at DESY, location Zeuthen (PITZ), was built to develop and optimize such photoinjectors. The PITZ facility is capable of generating long trains of electron bunches, which can be accelerated up to ~25 MeV/c. Studying and optimizing the longitudinal properties of the electron bunch is an important topic at PITZ. A streak system consisting of Silica Aerogel radiators, optical transition radiation (OTR) screens, optical transmission line, and a streak camera is used to study the longitudinal properties with an accuracy of some ps. Due to the high radiation level in the facility, many of the lenses in the optical transmission line have turned brown, reducing the efficiency of the system. Some of the lenses were recovered by baking them up to 180°C. In contrast, few sensitive objective lenses can not be baked, rather they were recovered via exposure to infrared radiation with the proper wave length. An overview of the system, the difficulties, and the modifications needed to overcome the radiation effects are presented.

MOPPP033	Diagnostics at PITZ 2.0 Beamline: Status and New Developments	emittance, diagnostics, dipole, FEL	634
	M. Otevřel, A. Donat, H.-J. Grabosch, M. Groß, L. Hakobyan, H.M. Henschel, L. Jachmann, M. Khojoyan, G. Klemz, W. Köhler, G. Koss, G. Kourkafas, M. Krasilnikov, K. Kusoljariyakul, H. Leich, J. Li, M. Mahgoub, D. Malyutin, B. Marchetti, J. Meissner, A. Oppelt, M. Penno, B. Petrosyan, M. Pohl, S. Riemann, M. Sachwitz, B. Schöneich, J. Schultze, A. Shapovalov, F. Stephan, F. Tonisch, G. Vashchenko, L.V. Vu, T. Walter, S. Weisse, R.W. Wenndorff, M. Winde DESY Zeuthen, Zeuthen, Germany G. Asova INRNE, Sofia, Bulgaria N.I. Brusova, L.V. Kravchuk, V.V. Paramonov RAS/INR, Moscow, Russia A. Gonnin, M. Joré, B. Mercier, C. Prevost, A. Variola LAL, Orsay, France I.I. Isaev MEPhI, Moscow, Russia Ye. Ivanisenko IERT, Kharkov, Ukraine D. Richter HZB, Berlin, Germany S. Rimjaem Chiang Mai University, Chiang Mai, Thailand A.A. Zavadtsev, D.A. Zavadtsev Nano, Moscow, Russia
	The main aim of the Photo Injector Test Facility at DESY, Zeuthen (PITZ) site is to develop and test an FEL photo injector system capable of producing high charge short electron bunches of lowest possible transverse emittance to allow optimum FEL performance. The last major beamline upgrade realized in the second half of the year 2011 completed the evolution of the PITZ setup ongoing since 2005. The most recent upgrades include the installation of a new RF deflecting cavity - a prerequisite for longitudinal emittance and high resolution slice emittance measurements and installation of a new dispersive section for longitudinal phase space diagnostics of the high energy electron bunches. The paper will give an overview on electron beam diagnostics at PITZ, including the above mentioned upgrades.

MOPPP034	Simulation of the Longitudinal Phase Space Measurement with Transverse Deflecting Structure at PITZ	cavity, dipole, emittance, simulation	637
	D. Malyutin, M. Krasilnikov, M. Otevřel, F. Stephan DESY Zeuthen, Zeuthen, Germany
	The main goal of the Photo Injector Test facility at DESY, Zeuthen site, (PITZ) is the development, optimization and detailed characterization of electron sources for the short wavelength Free Electron Lasers (FELs) like FLASH and the European XFEL. For successful operation of such type of FELs the injector must provide high quality electron bunches, enough short in duration with high charge and small transverse and longitudinal emittance values. Installation of the Transverse Deflecting Structure (TDS) at PITZ will provide the possibility for detailed characterization of bunch temporal profile, bunch transverse slice emittance and longitudinal phase space. The TDS cavity is currently installed at the PITZ beamline, and commissioning of the whole TDS system is expected in the spring 2012. In the first part of the paper the basic principles of the TDS deflector are described. In the next section, simulation of measurements by TDS cavity applied to the PITZ beam parameters is presented. The temporal resolution for different types of measurements is discussed. Systematic limitations are estimated.

MOPPP035	Initial Emittance and Temporal Response Measurement for GaAs Based Photocathodes	cathode, emittance, laser, cavity	640
	S. Matsuba Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan Y. Honda, T. Miyajima, T. Uchiyama, M. Yamamoto KEK, Ibaraki, Japan X.G. Jin Institute for Advanced Research, Nagoya, Japan Y. Takeda Nagoya University, Nagoya, Japan
	For future light source based on Energy Recovery Linac (ERL) is planned in KEK. For the ERL, an ultra low emittance and fast temporal response and high current electron source is needed. To achieve these requirements, a high voltage DC gun with a Negative Electron Affinity photo-cathode is under development. In this development, it is important to investigate the performance of photo-cathodes. We have constructed an ERL gun test stand to measure emittance and temporal profile. We use a solenoid scan technique for emittance measurements and a deflecting cavity technique for temporal profile measurements. In this presentation, we introduce KEK ERL gun test stand and beam test results.

MOPPP036	Progress in Reducing the Back-bombardment Effect in the ITC-RF gun for t-ACTS Project at Tohoku University	cathode, gun, dipole, simulation	643
	X. Li, H. Hama, F. Hinode, S. Kashiwagi, M. Kawai, T. Muto, K. Nanbu, Y. Tanaka Tohoku University, Research Center for Electron Photon Science, Sendai, Japan F. Miyahara KEK, Ibaraki, Japan
	An ITC (independently tunable cells) thermionic RF gun* has been developed to produce sub-picosecond electron pulses as part of the injector for coherent terahertz radiation at Tohoku University. Both experiments and simulations have shown that the back-bombardment (B.B.) effect on the LaB6 cathode is a serious issue for option. A numerical model has been developed to evaluate the temperature increase of the cathode due to B.B. in which a 2D equation for heat conduction is solved by taking the back-streaming electrons into account. Using this model we have studied the possibility of suppressing the B.B. by employing dipole field and optimization of the cathode radius, compared with experimental data. Other methods and the prospect of the RF gun will also be reported. * H. Hama et al., New J. Phys. 8 (2006) 292

MOPPP039	Masked Photocathode for Photoinjectors	cathode, emittance, laser, vacuum	649
	J. Qiang LBNL, Berkeley, California, USA
	Funding: This research was supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. This research used resources of the NERSC. In this paper, we propose using masked photocathode in photoinjector for generating high brightness electron beam. An electrode with small hole is used as a mask to shield a large size photocathode from accelerating vacuum chamber. Using a mask will significantly increase lifetime of a photocathode by rotating unexplored photocathode material behind the electrode into the hole. Furthermore, the mask helps reduce dark current or secondary electron emission from the photocathode material. It also provides a control of initial beam transverse emittances.

MOPPP040	Resistive Wall Heating of the Undulator in High Repetition Rate FELs	undulator, wakefield, impedance, FEL	652
	J. Qiang, J.N. Corlett, P. Emma LBNL, Berkeley, California, USA J. Wu SLAC, Menlo Park, California, USA
	Funding: Work supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. In next generation high repetition rate FELs, beam energy loss due to resistive wall wakefields will produce significant amount of heat. The heat load for a superconducting undulator (operating at low temperature), must be removed and will be expensive to remove. In this paper, we study this effect in an undulator proposed for a Next Generation Light Source (NGLS) at LBNL. We benchmark our calculations with measurements at the LCLS and carry out detailed parameter studies using beam from a start-to-end simulation. Our preliminary results suggest that the heat load in the undulator is about 2 W/m with an aperture size of 6 mm for nominal NGLS design parameters.

MOPPP041	Effect of Roughness on Emittance of Potassium Cesium Antimonide Photocathodes	emittance, cathode, laser, extraction	655
	T. Vecchione, J. Feng, H.A. Padmore, W. Wan LBNL, Berkeley, California, USA I. Ben-Zvi, M. Ruiz-Osés, L. Xue Stony Brook University, Stony Brook, USA D. Dowell SLAC, Menlo Park, California, USA T. Rao, J. Smedley BNL, Upton, Long Island, New York, USA
	Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences of the U. S. Department of Energy, under Contract DE-AC02-05CH11231, KC0407-ALSJNT-I0013, and DE-SC0005713 Here we present first measurements of the effect of roughness on the emittance of K2CsSb photocathodes under high fields. We show that for very thin cathodes the effect is negligible at up to 3 MV/m but for thicker and more efficient cathodes the effect becomes significant. We discuss ways to modify the deposition to circumvent this problem.

MOPPP042	Modeling Multi-bunch X-band Photoinjector Challenges	emittance, gun, linac, laser	658
	R.A. Marsh, S.G. Anderson, C.P.J. Barty, D.J. Gibson, F.V. Hartemann LLNL, Livermore, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. An X-band test station is being developed at LLNL to investigate accelerator optimization for future upgrades to mono-energetic gamma-ray (MEGa-Ray) technology at LLNL. The test station will consist of a 5.5 cell X-band rf photoinjector, single accelerator section, and beam diagnostics. Of critical import to the functioning of the LLNL X-band system with multiple electron bunches is the performance of the photoinjector. In depth modeling of the Mark 1 LLNL/SLAC X-band rf photoinjector performance will be presented addressing important challenges that must be addressed in order to fabricate a multi-bunch Mark 2 photoinjector. Emittance performance is evaluated under different nominal electron bunch parameters using electrostatic codes such as PARMELA. Wake potential is analyzed using electromagnetic time domain simulations using the ACE3P code T3P. Beam-loading effects and low level rf compensation schemes are explored as well, using a semi-analytic formalism and computer algorithm. Plans for multi-bunch experiments and implementation of photoinjector advances for the Mark 2 design will also be discussed.

MOPPP046	RF Gun Photocathode Research at SLAC	gun, cathode, laser, emittance	664
	E.N. Jongewaard, R. Akre, A. Brachmann, W.J. Corbett, S. Gilevich, K. Grouev, P. Hering, P. Krejcik, J.R. Lewandowski, H. Loos, T. M. Montagne, J. Sheppard, P. Stefan, A.E. Vlieks, S.P. Weathersby, F. Zhou SLAC, Menlo Park, California, USA
	Funding: DOE contract DE-AC02-76SF00515. LCLS is presently operating with a third copper photocathode in the original rf gun, with a quantum efficiency (QE) of ~1x10^-4 and projected emittance eNx,y=0.45 μm at 250 pC bunch charge. The spare LCLS gun is installed in the SLAC Accelerator Structure Test Area (ASTA), processed to the design rf gradient of >120 MV/m. As part of a wider photocathode R&D program, a UV laser system and additional gun diagnostics are being installed at ASTA to measure QE, QE lifetime, and electron beam emittance under a variety of operating conditions. The near-term goals are to test and verify the spare photocathode production/installation sequence, including transfer from the final holding chamber to the rf gun. Mid- and longer-term goals include development of a rigorous understanding of plasma and laser-assisted surface conditioning and investigation of new, high-QE photocathode materials. In parallel, an x-ray photoemission spectroscopy station is nearing completion, to analyze Cu photocathode surface chemistry. In this paper we review the status and anticipated operating parameters of ASTA and the spectroscopy test chamber.

MOPPP047	Characterization of the First SRF Electron Beam Source at the Naval Postgraduate School	cavity, cathode, SRF, coupling	667
	A.D. Holmes, A.B. Baxter, C.W. Bennett, J.R. Harris, J.W. Lewellen, R. Swent NPS, Monterey, California, USA J.M. Didoszak, J.M. Utschig ONR, Arlington, Virginia, USA
	In June 2011, the Naval Postgraduate school (NPS) received the 500 MHz Mark I quarter-wave superconducting RF (SRF) electron beam source and, among other firsts, completed the first cool down and characterization of an SRF beam source at a US Naval facility. The Mark I has a photocathode with adjustable position and uses a unique cascaded RF coupler design. As part of an on-going advanced electron source development project, the NPS Beam Physics Laboratory (BPL) team continues characterization of the Mark I cavity at various cathode stalk, coupler, and probe positions. Methods and experimentation used to measure the cavity Q and β, as well as characteristic results, with respect to coupler, cathode stalk, and probe positions are presented.

MOPPP050	Physics Results of the NSLS-II Linac Front End Test Stand	linac, emittance, simulation, gun	673
	R.P. Fliller, F. Gao, J. Rose, T.V. Shaftan, X. Yang BNL, Upton, Long Island, New York, USA G. Blokesch PPT, Dortmund, Germany C. Piel RI Research Instruments GmbH, Bergisch Gladbach, Germany
	Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The NSLS-II linac is produced by Research Instruments and will be commissioned in the spring of 2012. As part of the procurement, the linac front end consisting of the gun, prebunching cavity, and diagnostics was delivered early to BNL for testing. We designed a short beamline to supplement the Front End diagnostics to characterize the beam. These tests were instrumental in demonstrating the functioning of the gun, pinpointing technical problems at an early project stage and gaining experience with the linac gun by BNL staff prior to commissioning of the full linac. In this report we show the results of the tests, including charge, bunch length, and transverse emittance measurements and compare them with the relevant linac specifications.

MOPPP056	Injection Transient Motion at PLS-II	kicker, injection, septum, linac	688
	I. Hwang, T. Ha, Y.D. Joo, C. Kim, M. Kim, S.H. Kim, B.-J. Lee, E.H. Lee, S. Shin PAL, Pohang, Kyungbuk, Republic of Korea
	PLS-II is an upgraded third generation synchrotron which includes many insertion devices with improved beam properties. Top-up operation is short time-interval injection to make roughly constant current and is essential to provide high intensity beam. When the electrons are injected to synchrotron, the stored beam is disturbed by small error of the injection system and the beam quality at the beamline can be decreased. We present this injection transient motion at PLS-II.

MOPPP065	Effects of Geometrical Errors on the Field Quality in a Planar Superconducting Undulator	undulator, simulation, photon, status	708
	J. Bahrdt HZB, Berlin, Germany J. Bahrdt, Y. Ivanyushenkov ANL, Argonne, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Short-period superconducting undulators are being developed at the Advanced Photon Source (APS). The first test device is being fabricated. It is using a relatively short magnetic structure that will be replaced with a longer magnet in the second device. High quality magnetic field with the phase errors at a level of 2 degrees rms were achieved in the prototype magnets due to very accurate winding of the superconducting coils on the formers machined to about 10-μm precision. Manufacturing meters-long undulator structures to such tolerances would be very difficult or even impossible. It is therefore important to understand the effects of the mechanical tolerances in the coil manufacture process on the quality of the magnetic field. The effects of geometrical errors in the position of a superconducting winding in a planar structure are simulated with the RADIA software package. A field profile of a long non-ideal undulator magnet is then built and analyzed in terms of the first and second field integrals as well as phase errors. The results of the systematic study of the geometrical errors on the field quality are presented in this paper.

MOPPP068	Beam Heat Load and Pressure in the Superconducting Undulator Installed at ANKA	undulator, vacuum, storage-ring, simulation	717
	S. Casalbuoni, S. Gerstl, A.W. Grau, T. Holubek, D. Saez de Jauregui Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
	A superconducting undulator has been installed in the ANKA (ANgstrom source KArlsruhe) storage ring since March 2005. The beam heat load and pressure on the cold bore were analyzed in the first two years of operation, during which the undulator was operated mainly with open gap. We report here on a larger statistic of beam heat load and pressure data collected in the last years with the undulator operated at different gap positions. The effects of vacuum leaks in the storage ring on the superconducting undulator operation are also described.

MOPPP069	First Measurements of COLDDIAG: A Cold Vacuum Chamber for Diagnostics	solenoid, diagnostics, vacuum, insertion	720
	S. Gerstl, T. Baumbach, S. Casalbuoni, A.W. Grau, M. Hagelstein, T. Holubek, D. Saez de Jauregui Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany R. Bartolini, M.P. Cox, J.C. Schouten, R.P. Walker Diamond, Oxfordshire, United Kingdom M. Migliorati, B. Spataro INFN/LNF, Frascati (Roma), Italy I.R.R. Shinton UMAN, Manchester, United Kingdom
	Superconductive insertion devices can reach, for the same gap and period length, higher fields with respect to permanent magnet insertion devices. One of the still open issues for the development of superconductive insertion devices, is the understanding of the heat intake from the electron beam. COLDDIAG, a cold vacuum chamber for diagnostics was designed and built specifically for this purpose. With the equipped instrumentation, which covers temperature sensors, pressure gauges, mass spectrometers as well as retarding field analyzers it is possible to measure the beam heat load, total pressure, gas content as well as the flux of particles hitting the chamber walls. Here we report about the preliminary measurements and results of COLDDIAG installed in the Diamond storage ring.

MOPPP072	Performance of APPLE-II Type Quasi-Periodic Undulator at HiSOR	undulator, radiation, polarization, photon	729
	S. Sasaki, M. Arita, K. Goto, A. Miyamoto, T. Okuda HSRC, Higashi-Hiroshima, Japan
	A 1.8-m-long 78-mm-period quasi-periodic APLPE-II undulator was installed in the 700-MeV HiSOR storage ring of Hiroshima Synchrotron Radiation Center. At 23-mm nominal minimum gap, the fundamental photon energies are 3.1 eV, 6.5 eV, and 4.8 eV for horizontal linear, vertical linear, and circular polarization, respectively. The photon energies of observed fundamental and higher harmonic radiations are in good agreement with those of model calculations using measured undulator field and the HiSOR beam parameters. Also, observed flux thorough a slit and a grating monochromator was more than twice larger than that from previously installed 100-mm-period helical undulator for the whole range of radiation spectra. The feedforward COD correction was done to avoid the intensity fluctuation of photon beam in other BM beamlines due to the gap and phase motion of undulator. No fatal effect on the stored electron beam by installing the undulator was observed though a slight beam size change was observed at the minimum gap.

MOPPP074	Magnetic Field Measurement for a THz Undulator Using the Vibrating Wire Method	undulator, radiation, laser, resonance	732
	S. Kashiwagi, H. Hama, F. Hinode, M. Kawai, X. Li, T. Muto, K. Nanbu, Y. Tanaka Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	Funding: This work is supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (S), Contract #20226003. We constructed the undulator that is a basically a Halbach planer type for a generation of intense coherent terahertz radiation from the very short electron bunch. The period length of the undulator and the number of periods are 100 mm and 25, respectively. Its maximum magnetic field is 0.41 T and the K-value is 3.82 with 54 mm gap. The vibrating wire method is studied to measure the periodic magnetic field of the undulator. By measuring amplitudes and phases of standing waves excited on the wire by the Lorentz force between AC current and magnetic field, we can reconstruct the magnetic field distribution along the wire. The theoretical analysis has been performed for the THz undulator and derived a relation between a reproducibility of undulator field and the number of the harmonic mode to use for the reconstruction. A model experiment was demonstrated using 20cm wire and one pair of permanent magnet block. The theoretical study and the results of model experiment using the vibrating wire method will be shown in this conference.

MOPPP076	Design Considerations for a Hybrid Undulator Applied in a Terahertz FEL Oscillator	undulator, FEL, radiation, cavity	738
	B. Qin, M. Fan, Y.Q. Xiong Huazhong University of Science and Technology (HUST), Wuhan, People's Republic of China Y.J. Pei USTC/NSRL, Hefei, Anhui, People's Republic of China P. Tan HUST, Wuhan, People's Republic of China
	A planer undulator using hybrid permanent magnet scheme was designed for a FEL based 1THz~3THz radiation source. The influence of the undulator magnetic field errors, including peak field shift and field integrals errors, on the coherent radiation performance such as the gain per pass is investigated. And finally specifications of the undulator are determined.

MOPPP085	Single Electron Dynamic of Microwave Undulator	undulator, FEL, radiation, free-electron-laser	753
	C. Chang, J. Neilson, C. Pellegrini, M. Shumail, S.G. Tantawi SLAC, Menlo Park, California, USA
	The analytical and numerical calculations for the dynamic of single electron and beam in RF undulator have been conducted and compared. The transverse and longitudinal velocity, trajectory, energy variation, and the spontaneous radiation are studied. It is found that the forward and backward wave (FW/BW) components have different contribution on electron motion and radiation, most of the energy spread comes from FW component, in other words, the effect of FW on modulating the electron energy is much stronger than that of BW for the same undulating-amplitude value, which mechanism has been analyzed.

MOPPP088	Control of Nonlinear Dynamics by Active and Passive Methods for the NSLS-II Insertion Devices	undulator, polarization, insertion, insertion-device	759
	J. Bengtsson, O.V. Chubar, C.A. Kitegi, T. Tanabe BNL, Upton, Long Island, New York, USA
	Funding: US DOE, Contract No. DE-AC02-98CH10886. Nonlinear dynamics effects from insertion devices (IDs) are known to affect the electron beam quality of third generation synchrotron light sources. In particular, beam lifetime, dynamical aperture and injection efficiency. Methods to model the IDs' non-linear effects are known, e.g. by second-order (in the inverse electron energy) kick maps. Methods to compensate these effects are known as well, e.g. by first-order thin or thick magnetic kicks introduced by "magic fingers," "L-shims," or "current strips." However, due to physical or technological constraints, these corrections are typically only partial. Therefore, a precise model is required for a correct minimization of the residual nonlinear dynamics effects for the combined magnetic fields of the ID and compensating magnets. We outline a systematic approach for such predictions, based on 3D magnetic field and local trajectory calculation in the ID by the Radia code, and particle tracking by Tracy-3. The optimal geometry for the compensating magnets is determined from these simulations using a combination of linear algebra and genetic optimization.

MOPPP090	Spectral Performance of Segmented Adaptive-Gap In-Vacuum Undulators for Storage Rings	undulator, vacuum, photon, radiation	765
	O.V. Chubar, J. Bengtsson, A. Blednykh, C.A. Kitegi, G. Rakowsky, T. Tanabe BNL, Upton, Long Island, New York, USA J.A. Clarke STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: US DOE, Contract No. DE-AC02-98CH10886. We propose an approach to the optimization of segmented in-vacuum undulators, in which different segments along an undulator may have different gaps and periods. This enables close matching between the gaps and the vertical "envelope" of electron beam motion in a storage ring straight section (carefully satisfying the associated vertical "stay clear" constraint) and, at the same time, precise tuning of all the segments to the same fundamental photon energy. Thanks to this, the vertical gaps in segments located closer to straight section center can be smaller than at extremities, and so the entire undulator structure can offer better magnetic performance, compared to the case of a standard undulator with constant gap (and period) over its length. We will present magnetic field, radiation flux, brightness and intensity calculation results for such segmented adaptive-gap in-vacuum undulators and demonstrate their gain in spectral performance over standard in-vacuum undulators, both for room-temperature and cryo-cooled realizations.

MOPPP091	Recent Developments at the DELTA THz Beamline	laser, radiation, storage-ring, undulator	768
	P. Ungelenk, M. Bakr, H. Huck, M. Höner, S. Khan, R. Molo, A. Nowaczyk, A. Schick, M. Zeinalzadeh DELTA, Dortmund, Germany
	Funding: Work supported by DFG, BMBF, and by the Federal State NRW. During 2011, a new dedicated THz beamline has been constructed and commissioned at DELTA, a 1.5 GeV synchrotron light source operated by the TU Dortmund University. This beamline enables extracting and detecting coherent THz pulses caused by a laser-induced density modulation of the electron bunches. Ongoing experiments aim at characterizing the THz radiation as well as investigating the evolution of the density modulation over subsequent revolutions following the initial laser-electron interaction in an undulator.

MOPPR001	Resonant Spin Depolarisation Measurements at the SPEAR3 Electron Storage Ring	storage-ring, lattice, polarization, synchrotron	771
	K.P. Wootton, R.P. Rassool The University of Melbourne, Melbourne, Australia M.J. Boland, Y.E. Tan ASCo, Clayton, Victoria, Australia W.J. Corbett, M.H. Donald, X. Huang, R.R. Ortiz, J.A. Safranek, K. Tian SLAC, Menlo Park, California, USA
	Accurate electron beam energy measurements are valuable for precision lattice modelling of high-brightness light sources. At SPEAR3 the beam energy was measured using the resonant spin depolarisation method with striplines to resonantly excite the spin tune and a sensitive NaI scintillator beam loss monitor was used to detect resulting changes in Touschek lifetime. Using the combined apparatus an electron beam energy of 2.997251(7) GeV was measured, giving a relative uncertainty better than 3x10^-6. The measured momentum compaction factor was found to be in close agreement with the numerical model value using rectangular defocussing gradient dipoles with measured magnetic field map profiles. In this paper we outline the chosen experimental technique, with emphasis on its applicability to electron storage rings in general.

MOPPR003	Beam Diagnostic Systems for the TRIUMF e-linac	linac, TRIUMF, diagnostics, EPICS	777
	J.M. Abernathy, D. Karlen, M.O. Pfleger, P.R. Poffenberger, D.W. Storey Victoria University, Victoria, B.C., Canada F. Ames, P.S. Birney, D.P. Cameron, J.V. Holek, S.Y. Kajioka, S. Kellogg, M. Lenckowski, M. Minato, W.R. Rawnsley, J.E. Richards, V.A. Verzilov TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	Funding: NSERC, CFI, BCKDF. The TRIUMF electron linac will include a suite of diagnostics systems, including current, beam position, and beam profile monitors. This talk will present an overview of the diagnostic systems and give details about the view screen system, having both scintillator and OTR foils. Results from tests with the prototype low energy beam transport system will be shown. Diagnostic systems are particularly challenging for the e-linac due to the 500 kW beam power envisaged, with beam currents up to 10 mA at 50 MeV.

MOPPR007	Investigation of Techniques for Precise Compton Polarimetry at ELSA	polarization, photon, laser, simulation	783
	R. Zimmermann, W. Hillert ELSA, Bonn, Germany
	Funding: Work supported by DFG within SFB/TR16 A Compton polarimeter is currently being installed at the Electron Stretcher Facility ELSA to monitor the degree of polarization of the stored electron beam. For this purpose, circularly polarized light that is emitted by a laser and backscattered off the beam has to be detected. When the polarization of the laser light is switched from left-hand to right-hand circular polarization, the spatial distribution of the backscattered photons is shifted. The extent of this modification is a measure of the beam's polarization degree. Two different experimental techniques that are suitable for a measurement of the effect were compared and evaluated closer through numerical simulations that will be presented in this contribution.

MOPPR008	The Beam Loss Monitoring System at ELSA	injection, extraction, booster, monitoring	786
	D. Proft, A. Balling, F. Frommberger, W. Hillert ELSA, Bonn, Germany
	A new diagnostic tool to monitor beam loss in the storage ring at the Electron Stretcher Facility ELSA has been set up. It enables the investigation of causes for electron loss in real time, providing an essential tool needed to achieve the planned beam current upgrade from 30 mA to 200 mA. The monitoring system consists of 32 pin-diode based radiation detectors spread around the storage ring. Therefore, individual electron loss can be localized after each quadrupole. The readout system was designed to allow an integration of single loss events within 70 μs in order to be able to correlate these events to machine state changes. The used monitoring hardware and readout system will be detailed. Furthermore first measurements of the beam loss during injection, the fast energy ramp during acceleration and the extraction phase will be presented.

MOPPR009	Dynamic Closed Orbit Correction During the Fast Energy Ramp of ELSA	closed-orbit, polarization, acceleration, controls	789
	J.-P. Thiry, A. Balling, A. Dieckmann, F. Frommberger, W. Hillert ELSA, Bonn, Germany
	ELSA is a fast ramping stretcher ring supplying polarized electrons to hadron physics experiments. To preserve the degreee of polarization, it is necessary to continuously correct the vertical orbit when accelerating the beam from 1.2 GeV to 2.4 GeV. Acceleration is performed within 300 ms, thus with a ramping speed of 4 GeV/s. During the acceleration, beam positions are measured at a rate of 1 kHz using 32 beam position monitors, which are mounted close to the quadrupole magnets. The demanding task is to achieve a vertical rms deviation not exceeding 50 μm all along the fast energy ramp. Therefore, dynamic orbit corrections are applied by means of offline feed-forward techniques, driving 32 vertical steerer magnets which can change currents in less than 10 ms. In our contribution, we show the used concepts and the implementation of the precise closed orbit correction system at ELSA.

MOPPR011	A New Diagnostic Beamline at ELSA	synchrotron, radiation, synchrotron-radiation, diagnostics	795
	S. Zander, F. Frommberger, P. Hänisch, W. Hillert, B. Neff ELSA, Bonn, Germany
	Funding: Funded by the DFG within the SFB / TR 16. At the Electron Stretcher Facility (ELSA), a new synchrotron light diagnostic Beamline has been installed in order to perform high resolution, transversal and longitudinal beam profile measurements by analyzing the emitted synchrotron light. For this purpose, the main deflecting AL mirror selects a wide range of wavelengths from 200–800 nm out of the whole synchrotron spectrum. The setup of the beamline and its relevant components will be presented.

MOPPR012	Beam Induced Fluorescence Monitors for FAIR	vacuum, ion, target, antiproton	798
	F. Becker, C.A. Andre, C. Dorn, P. Forck, R. Haseitl, B. Walasek-Höhne GSI, Darmstadt, Germany T. Dandl, T. Heindl, A. Ulrich TUM/Physik, Garching bei München, Germany
	Online profile diagnostic is preferred to monitor intense hadron beams at the Facility of Antiproton and Ion Research (FAIR). One instrument for beam profile measurement is the gas based Beam Induced Fluorescence (BIF)-monitor. It relies on the optical fluorescence of residual gas, excited by beam particles. Depending on the beam parameters and vacuum constraints, BIF monitors can be operated at base pressure or in dedicated local pressure bumps. Spectroscopic data in nitrogen and rare gases confirms an exploitable dynamic range from UHV to atmospheric pressure. Optical transitions and corresponding beam profiles are discussed for gas pressures from 10^-3 to 30 mbar. Fundamental limitations for some application scenarios will be addressed as well.

MOPPR014	Installation and Test of a Beam Loss Monitor System for the S-DALINAC	controls, monitoring, background, radiation	804
	R. Stegmann, U. Bonnes, C. Burandt, R. Eichhorn, F. Hug, L.E. Jürgensen, N. Pietralla TU Darmstadt, Darmstadt, Germany D. Proft ELSA, Bonn, Germany
	Funding: This work is supported by the DFG through SFB 634. The superconducting Darmstadt linear accelarator S-DALINAC is designed for accelerating electrons up to energies of 130 MeV for measurements in nuclear physics at small momentum transfers. For the purpose of machine protection and in order to increase reliability and efficiency an efficient tool for on-line measurements of beam losses down to electron energies of 1 MeV is desirable. Therefore a system of beam-loss monitors has been developed, installed, and tested. The system consists of commercially availiable PIN-diods and newly developed electronics. Implementation in the S-DALINAC's control system is done via EPICS IOC. We will report on the setup of the beam-loss monitoring system and on its initial performance in first tests.

MOPPR015	Bunch-by-bunch Feedback Systems at the DELTA Storage Ring	feedback, kicker, synchrotron, injection	807
	M. Höner, M. Bakr, H. Huck, S. Khan, R. Molo, A. Nowaczyk, A. Schick, P. Ungelenk, M. Zeinalzadeh DELTA, Dortmund, Germany
	Funding: Work supported by BMBF (05K10PEB) At the DELTA 1.5-GeV electron storage ring operated as a synchrotron radiation source by the TU Dortmund University, bunch-by-bunch feedback systems have been recently installed and commissioned to detect and suppress longitudinal as well as transverse multibunch instabilities. Besides that, the feedback systems are used as a diagnostics tool. Growth rates of multibunch instabilities and their dependence on the beam current have been measured. Additionally, the oscillation amplitudes of electron bunches have been studied during the injection process.

MOPPR016	Femtosecond Level Electron Bunch Diagnostic at Quasi – CW SRF Accelerators: Test Facility ELBE	diagnostics, SRF, laser, photon	810
	M. Gensch, C. Kaya, U. Lehnert, P. Michel, Ch. Schneider, W. Seidel HZDR, Dresden, Germany G. Geloni European XFEL GmbH, Hamburg, Germany M. Helm FZD, Dresden, Germany H. Schlarb, A. Shemmary, N. Stojanovic DESY, Hamburg, Germany
	Funding: BMBF through the PIDID proposal and HGF through the ARD initiative At the srf based prototype cw accelerator ELBE a new electron beamline, providing for femtosecond electron bunches with nC bunch charges and repetition rates in the 1 – 200 KHz regime and with pC bunch charge and repetition rates of 13 MHz is currently constructed. The 40 MeV electrons will be used in photon-electron interaction experiments with TW and PW class laser and the generation of broad band and narrow bandwidth coherent THz pulses. In this paper we outline ideas for novel online diagnostics of the electron bunch properties (e.g. arrival time and bunch form) based on the time and frequency domain analysis of the emitted coherent THz radiation but also based on direct measurements by e.g. electro-optic sampling. The suitability of ELBE as a testbed for diagnostic of future cw X-ray photon sources (e.g. energy recovery linacs) will be discussed.

MOPPR017	Preliminary Measurement Results of the Upgraded Energy BPM at FLASH	pick-up, LLRF, controls, FEL	813
	U. Mavrič, M. Felber, C. Gerth, H. Schlarb DESY, Hamburg, Germany W. Jałmużna, A. Piotrowski TUL-DMCS, Łódź, Poland
	The energy beam position monitor in the dispersive section of the two bunch compressors is a valuable instrument for regular operation of FLASH. Recently, an upgrade of the existing instrument to a uTCA form factor has been started. The basic principle of the time-of-flight measurement will remain the same, however the detection of the phases and amplitudes of two pulses has been moved to the programmable gate array. Other changes include different RF frequencies of detection, optimization of the front-end section and integration into the control system. A preliminary version of the system has been tested at FLASH and the results are presented in the paper.

MOPPR018	Beam Halo Monitor for FLASH and the European XFEL	diagnostics, free-electron-laser, laser, pick-up	816
	A. Ignatenko, N. Baboi, O. Hensler, M. Schmitz, K. Wittenburg DESY, Hamburg, Germany H.M. Henschel, W. Lange, W. Lohmann DESY Zeuthen, Zeuthen, Germany A. Ignatenko BTU, Cottbus, Germany S. Schuwalow Uni HH, Hamburg, Germany
	The Beam Halo Monitor for Free-electron Laser in Hamburg (FLASH) based on pCVD diamond and monocrystalline artificial sapphire sensors has been successfully commissioned in September 2009. It is a part of the beam dump diagnostics and ensures safe beam dumping. Its description and the experience gained during its operation are given. The ideas on the design and aspects of operation of the similar systems at FLASH II and the European XFEL are presented.

MOPPR019	Beam Profile Imaging Based on Backward Transition Radiation in the Extreme Ultraviolet Region	radiation, target, FEL, diagnostics	819
	L.G. Sukhikh, S. Bajt, G. Kube DESY, Hamburg, Germany W. Lauth IKP, Mainz, Germany Yu.A. Popov, A. Potylitsyn Tomsk Polytechnic University, Tomsk, Russia
	Backward transition radiation (BTR) in the optical spectral region is widely used for beam profile diagnostics in modern electron linacs. However, the experience from linac based light sources shows that BTR diagnostics might fail because of coherence effects in the emission process. To overcome this problem of coherent emission it was proposed to use BTR in the extreme ultraviolet (EUV) region, and measurements of the angular EUV BTR distribution were presented in Ref. . This contribution summarizes the results of a beam profile imaging experiment using EUV BTR. The experiment was carried out using the 855 MeV electron beam of the Mainz Microtron MAMI. EUV BTR was generated at a molybdenum target deposited onto a silicon substrate, and imaging was realized using a spherical multilayer mirror which was optimized for a wavelength of 19 nm. Preliminary results will be presented and compared to ordinary optical BTR imaging together with a discussion of future possibilities of the proposed diagnostic method. L.G. Sukhikh et al., Nucl. Instrum. Methods A623, 567 (2010). ** L.G. Sukhikh et al., Proc. of DIPAC-2011, Hamburg (Germany), 544 (2011).

MOPPR024	Non-intercepting Emittance Measurements by means of Optical Diffraction Radiation Interference for High Brightness Electron Beam	radiation, quadrupole, emittance, target	831
	A. Cianchi Università di Roma II Tor Vergata, Roma, Italy V. Balandin, N. Golubeva, K. Honkavaara, G. Kube DESY, Hamburg, Germany M. Castellano, E. Chiadroni INFN/LNF, Frascati (Roma), Italy L. Catani INFN-Roma II, Roma, Italy
	Conventional intercepting transverse electron beam diagnostics, e.g. based on Optical Transition Radiation (OTR), cannot tolerate high power beams without remarkable mechanical damages of the diagnostics device. Optical Diffraction Radiation (ODR) is an excellent candidate for the measurements of the transverse phase space parameters in a non-intercepting way. One of the main limitations of this method is the low signal to noise ratio, mainly due to the unavoidable synchrotron radiation background. This problem can be overcome by using ODRI (Optical Diffraction Radiation Interference). In this case the beam goes through two slits opened on metallic foils, placed in a distance shorter than the radiation formation zone. Thanks to the shielding effect of the first screen a nearly background-free ODR interference pattern can be measured allowing the determination of the beam size and the angular divergence. Here we report the first measurements, carried out at FLASH (DESY, Germany), of the beam emittance using ODRI. Our results demonstrate the unique potential of this technique.

MOPPR025	The BPM DAQ System Upgrade for SuperKEKB Injector Linac	linac, emittance, positron, injection	834
	M. Satoh, K. Furukawa, F. Miyahara, T. Suwada KEK, Ibaraki, Japan T. Kudou, S. Kusano MELCO SC, Tsukuba, Japan
	The non-destructive beam position monitor (BPM) is indispensable diagnostic tool for the stable beam operation. In the KEK Linac, approximately nineteen BPMs with the strip-line type electrodes are used for the beam orbit measurement and feedback. In addition, some of them are also used for the beam energy feedback loops. The current DAQ system consists of the fast digital oscilloscopes. A signal from each electrode is analyzed with a predetermined response function up to 50 Hz. The beam position resolution of current system is limited to about 0.5 mm because of ADC resolution. Towards SuperKEKB project, we have a plan to upgrade the BPM DAQ system since the Linac should provide the smaller emittance beam. We will report the system description of the new DAQ system and the results of performance test in detail.

MOPPR029	Upgrade of Ionization Profile Monitor (IPM) in the J-PARC 3-GeV RCS	ion, vacuum, status, space-charge	840
	H. Harada, K. Yamamoto, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	Ionization Profile Monitors (IPM) were installed and operated in the J-PARC 3-GeV RCS for the observation of circulating beam profile. In IPM system, ions produced by the beam passing through beam chamber lead to Multi Channel Plate (MCP) by electric field, and the signals from the MCP are observed as the beam profile. The IPM system has an upgrade plan for the optimization of the electric fields. This will be reported the upgrade status of the IPM.

MOPPR032	Electron Beam Diagnostics based on Transverse Feedback System at Duke Storage Ring	storage-ring, feedback, monitoring, FEL	849
	W. Xu, D.H. He USTC/NSRL, Hefei, Anhui, People's Republic of China J.Y. Li, W. Wu, Y.K. Wu FEL/Duke University, Durham, North Carolina, USA
	Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033. To combat electron beam instabilities, a field programmable gate array (FPGA) based bunch-by-bunch transverse feedback (TFB) has been developed for the Duke storage ring. While it is capable of suppressing transverse beam instabilities for multi-bunch operation, the TFB system has not been needed for typical operation of the Duke storage ring FEL. To explore the great potential of this system, we have focused on the development of TFB based beam diagnostics. A TFB based tune measurement system has been developed using two methods: the tune scan method and tune monitoring method. With the tune monitoring method, a much faster method of the two, we have studied the tune stability of the electron beam in the Duke storage ring. This tune measurement system also allows us to conduct chromaticity measurements more quickly, compared with the existing chromaticity measurement system using a network analyzer. Finally, the TFB based tune system has been used to calibrate the tune knob and chromaticity knob for the Duke storage ring.

MOPPR034	A Laser Wire System at Electron Beam Transport Line in BEPCII	laser, photon, positron, simulation	852
	C. Zhang, J. Cao, Q.Y. Deng, Y.F. Sui IHEP, People's Republic of China
	Funding: National Natural Science Foundation of China A Laser Wire system is under development at transport line in BEPCII (Beijing Electron Positron Collider). The structure of whole system is briefly described in this paper. Some work on laser and detector are presented. We also discussed the challenge of Laser Wire and some other things that can affect measurement. According to the plan, the Laser Wire will be installed in electron beam transport line in the summer of 2012.

MOPPR035	Study of the Signal Processing System for a Cavity Beam Position MonitorS	cavity, FEL, factory, simulation	855
	B.P. Wang, Y.B. Leng, L.Y. Yu, W.M. Zhou SINAP, Shanghai, People's Republic of China Z.C. Chen, R.X. Yuan, N. Zhang SSRF, Shanghai, People's Republic of China
	A cavity beam position monitor (CBPM), which can realize nanometer-level resolution as reported, is important and indispensable for a free electron laser (FEL) facility. A prototype of CBPM, with resonant frequency of 5712 MHz, has been installed in the Shanghai deep ultraviolet free-electron laser source (SDUV-FEL) facility. A plug & play CBPM signal processor based on a broadband oscilloscope embedded IOC and FFT technology has been developed to do quick evaluation of prototype. According to the evaluation results, a series of simulation using Monte Carlo simulation method, has been carried as a guideline for the design of dedicated CBPM signal processing system. The development progress of signal processing system will be introduced as well.

MOPPR040	Design and Measurements of a Test Stand for the SEM-Grid System of the ESS-BILBAO	vacuum, diagnostics, emittance, linac	867
	D. Belver, J. Feuchtwanger, P.J. González ESS Bilbao, LEIOA, Spain F.J. Bermejo Bilbao, Faculty of Science and Technology, Bilbao, Spain V. Etxebarria, J. Jugo University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain
	In the framework of the ESS-Bilbao accelerator, a test stand for the development of Secondary Electron EMission grid (SEM-Grid) has been designed and manufactured as a part of the diagnostics system for beam profile measurements. This test stand is a vacuum system based on an EQ 22/35 electron source from SPECS used as a beam injector. This electron source has an energy range from 0 to 5 KeV and a maximum beam current up to 200 μA. Although we have thought in a SEM-Grid of 40 wires (20 wires in each X and Y direction), two prototypes of 16 wires (8x8) of 250 μm diameter and spaced 1 and 2 mm, respectively, have been developed due to its easier implementation and tested in the test stand. In order to develop an electronics readout system for the SEM-Grid, first studies of the prototype signals have been done. The secondary emission current of each wire will be integrated and amplified to provide a significant voltage signal that can be measured by our acquisition system. A description of the SEM-Grid test stand and the measurements developed is given here.

MOPPR047	Study of the Response of Low Pressure Ionisation Chambers	proton, target, monitoring, synchrotron	888
	E. Nebot Del Busto, B. Dehning, E. Effinger, V. Grishin, J.F. Herranz Alvarez CERN, Geneva, Switzerland
	The Beam Loss Monitoring System (BLM) of the Large Hadron Collider (LHC) is based on parallel plate Ionization Chambers (IC) with active volume ~1.5l and a nitrogen filling gas at 0.1 bar overpressure. At the largest loss locations, the ICs generate signals large enough to saturate the read-out electronics. A reduction of the active volume and filling pressure in the ICs would decrease the amount of charge collected in the electrodes, and so provide a higher saturation limit using the same electroncis. This makes Little Ionization Chambers (LIC) filled with both reduced pressure and active volume a good candidate for these high radiation areas. In this contribution we present measurements performed with several LIC monitors with reduced active volume and various filling pressures. These detectors were tested under various conditions with different beam setups, with standard LHC ICs used for calibration purposes.

MOPPR059	Modeling Space-charge and its Influence on the Measurement of Phase Space in ALICE by Tomographic Methods	space-charge, quadrupole, injection, diagnostics	918
	M.G. Ibison, D.J. Holder The University of Liverpool, Liverpool, United Kingdom K.M. Hock, B.D. Muratori, A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: STFC. ALICE is an experimental electron accelerator designed to operate over a range of energies up to 35 MeV, and with up to 80 pC bunch charge. A dedicated tomography diagnostic section allows measurement of the transverse phase space with different beam parameters. In the low-energy, high-charge regime, space charge effects must be considered: to quantify these effects, the tracking code GPT has been used to simulate beams in the tomography diagnostic section. The results can be compared with simplified models, and with experimental measurements.

MOPPR067	Simulations of Fast X-ray Detectors Based on Multichannel Plates	photon, simulation, scattering, cathode	939
	Z. Insepov, B.W. Adams, J. Norem ANL, Argonne, USA V. Ivanov Muons, Inc, Batavia, USA
	Funding: Argonne National Laboratory High-performance detectors with high spatial and time resolutions are required for imaging of fast processes, time-resolved coherent scattering, and time-resolved x-ray spectroscopy. Recent developments in micro-channel plate (MCP) technology are important for sub-ns and 2d-spatially resolving x-ray detection. A Monte Carlo code was used to calculate the yields of secondary electrons emitted from a photo-cathode irradiated by X-rays, E=1-10 keV. Several photo-cathode materials were tested, including Al2O3, MgO, carbon, copper, WO3. The calculated emissive characteristics were used as input parameters of a second Monte Carlo code that was capable of calculating the gain/time characteristics of the MCP based X-Ray detector. A new type of X-Ray detector based on MCPs coated by resistive and emissive layers inside the pores by using atomic-layer deposition (ALD) promises a large parameter space where optimizations can take place. These optimizations for x-ray-specific applications are expected to improve the spatial resolution to 100 microns and the time resolution to 50 ps, and the development of high-quantum-yield photo-cathodes based on MCPs with grazing incidence inside the pores.

MOPPR070	Beam Profile Measurement in MTA Beam Line for High Pressure RF Cavity Beam Test	cavity, proton, diagnostics, linac	948
	M.R. Jana, A.D. Bross, S. Geer, C. Johnstone, T. Kobilarcik, G.M. Koizumi, M.A. Leonova, A. Moretti, M. Popovic, T.A. Schwarz, A.V. Tollestrup, K. Yonehara Fermilab, Batavia, USA M. Chung Handong Global University, Pohang, Republic of Korea M.G. Collura Politecnico di Torino, Torino, Italy B.T. Freemire, P.M. Hanlet, Y. Torun IIT, Chicago, Illinois, USA
	Funding: This work is supported by the United States Department of Energy under contract DE-AC02-07CH11359. The recent High Pressure RF (HPRF) cavity experiment at the MuCool Test Area (MTA) used a 400 MeV Linac proton beam to study the beam loading effect. When the energetic proton beam passes through the cavity, it ionizes the inside gas and produces electrons. These electrons consume RF power inside the cavity. The number of electrons produced per cm inside the cavity (at 950 psi Hydrogen gas) per incident proton is 1200. The measurement of beam position and profile are necessary. The MTA is a flammable gas (Hydrogen) hazard zone, so we have developed a passive beam diagnostic instrument using a Chromox-6 scintillation screen and CCD camera. This paper presents quantitative information about beam position and beam profile. A neutral density filter was used to avoid saturation of the CCD camera. Image data is filtered and fitted with a Gaussian function to compute the beam size. The beam profile obtained from the scintillation screen will be compared with a multi-wire beam profile.

MOPPR071	Initial Results of Transverse Beam Profile Measurements Using a LYSO:Ce Crystal	radiation, diagnostics, controls, laser	951
	A.S. Johnson, A.H. Lumpkin, T.J. Maxwell, J. Ruan, J.K. Santucci, C.C. Tan, R.M. Thurman-Keup, M. Wendt Fermilab, Batavia, USA
	A prototype transverse beam profile monitor for eventual use at the Advanced Superconducting Test Accelerator (ASTA) has been tested at the Fermilab A0 Photoinjector. Results from low-charge (20 pC) studies indicate that a LYSO:Ce scintillator will be a viable replacement for a YAG:Ce scintillator when using intercepting radiation convertor screens for beam profiling. We will also describe the planned implementation of LYSO:Ce crystals to mitigate the coherent optical transition radiation due to the microbunching instability through the use of band-pass filters and specially timed cameras.

MOPPR073	Analysis of Resonant TE Wave Modulation Signals for Electron Cloud Measurements	resonance, coupling, factory, cavity	957
	S. De Santis LBNL, Berkeley, California, USA D. Alesini INFN/LNF, Frascati (Roma), Italy J.P. Sikora CLASSE, Ithaca, New York, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy under Contracts DE-FC02-08ER41538, DE-AC02-05CH11231. Recent TE wave measurements of the electron cloud density in the beampipe at CesrTA and DAΦNE have shown that, especially near cutoff, the microwave excitation takes place by coupling to a standing wave, rather than to a propagating TE mode. With the beampipe acting as a resonant cavity, the effect of the periodic electron cloud density is a modulation of the cavity's resonant frequency. As a result, the measured sidebands are a combination of amplitude, phase, and frequency modulation, as the periodic cloud density modulates this resonant frequency. The quality factor Q of the resonance will determine its response to transients in the electron cloud density, and the resulting effect on modulation sidebands. In order to estimate the peak electron cloud density and its spacial distribution, knowledge of the Q and the standing wave pattern need to be determined, either by experimental measurements or simulation codes. In this paper we analyze the dependence of the modulation sidebands on the electron cloud density in two different regimes, when the cloud rise/decay time is much longer, or much shorter than the filling time of the resonance.

MOPPR074	Using TE Wave Resonances for the Measurement of Electron Cloud Density	resonance, cavity, simulation, vacuum	960
	J.P. Sikora, M.G. Billing, D. L. Rubin, R.M. Schwartz CLASSE, Ithaca, New York, USA D. Alesini INFN/LNF, Frascati (Roma), Italy B.T. Carlson CMU, Pittsburgh, Pennsylvania, USA S. De Santis LBNL, Berkeley, California, USA K.C. Hammond Harvard University, Cambridge, Massachusetts, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy under Contracts DE-FC02-08ER41538, DE-AC02-05CH11231. In the past few years, electron cloud density has been measured by means of its effect on TE waves propagated through the accelerator vacuum chamber. This technique has been the object of careful studies and has been used in several laboratories around the world (CERN, SLAC, FNAL, Cornell, INFN-LNF). Recent measurements at CesrTA and DAΦNE show that in a majority of practical cases, the theoretical model that relates the cloud density to the phase shift induced on a TE wave propagating in beam pipe may not be the correct one. Instead, the measurement results have to be analyzed considering the effect of the electron cloud on a standing wave excited between the input and output couplers - typically Beam Position Monitors (BPMs). This standing wave pattern is not confined to the portion of beampipe between the BPMs and must be understood in order to correctly interpret the measurement. In this paper we present evidence that the transmission function near cutoff between two BPMs is the result of coupling to standing waves trapped in the vacuum chamber. This evidence includes measurements at DAΦNE, Cesr-TA, a test waveguide, computer EM simulations, and analytical calculations.

MOPPR075	Status of the APEX Beam Diagnostic and First Measurements	laser, diagnostics, cathode, gun	963
	D. Filippetto, M.J. Chin, C.W. Cork, S. De Santis, L.R. Doolittle, W.E. Norum, C. F. Papadopoulos, G.J. Portmann, D.G. Quintas, F. Sannibale, R.P. Wells, M.S. Zolotorev LBNL, Berkeley, California, USA
	The APEX project aims to the construction of a high brightness high repetition rate photo-injector at LBNL. In its first phase a 750 keV electron bunch is produced at a maximum repetition rate of 1 MHz, with an adjustable charge per bunch spanning the pC-to-nC region. A load lock system is foreseen to test different cathodes without the need of breaking the vacuum and the downstream diagnostic is used to characterize the photo-emitted beam brightness. In the initial phase the main effort is directed toward the measurement of photocurrent, dark current, thermal emittance and electron beam kinetic energy. In a successive phase, diagnostic for full 6D phase space characterization of space charge dominated beams will be added to the beamline. We report and discuss the present diagnostic beamline layout, first beam measurements and future upgrades.

MOPPR080	Wire Scanner Beam Profile Measurements: LANSCE Facility Beam Development	controls, feedback, target, linac	975
	J.D. Gilpatrick, Y.K. Batygin, F. Gonzales, M.E. Gruchalla, V.G. Kutac, D. Martinez, C. Pillai, S. Rodriguez Esparza, J.D. Sedillo, B.G. Smith LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the U.S. Department of Energy. The Los Alamos Neutron Science Center (LANSCE) is replacing Wire Scanner (WS) beam profile measurement systems. Three beam development tests have taken place to test the new wire scanners under beam conditions. These beam development tests have integrated the WS actuator, cable plant, electronics processors and associated software and have used H⁻ beams of different beam energy and current conditions. In addition, the WS measurement-system beam tests verified actuator control systems for minimum profile bin repeatability and speed, checked for actuator backlash and positional stability, tested the replacement of simple broadband potentiometers with narrow band resolvers, and tested resolver use with National Instruments Compact Reconfigurable Input and Output (cRIO) Virtual Instrumentation. These beam tests also have verified how trans-impedance amplifiers react with various types of beam line background noise and how the cable plants can be simplified without generating unwanted noise currents. This paper will describe these beam development tests and show some resulting data.

MOPPR081	Wire Scanner Beam Profile Measurements for the LANSCE Facility	EPICS, controls, linac, LabView	978
	J.D. Gilpatrick, M.E. Gruchalla, D. Martinez, C. Pillai, S. Rodriguez Esparza, J.D. Sedillo, B.G. Smith LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the U.S. Department of Energy. The Los Alamos Neutron Science Center (LANSCE) is replacing beam profile measurement systems, commonly known as Wire Scanners (WS’s). Using the principal of secondary electron emission, the WS measurement system moves a wire or fiber across an impinging particle beam, sampling a projected multi-bin distribution. Because existing WS actuators and electronic components are either no longer manufactured or home-built with antiquated parts, a new wire scanner beam profile measurement is being designed, fabricated, and tested. The goals for these new wire scanner include using off-the-shelf components while eliminating antiquated components, providing quick operation while allowing for easy maintainability, and tolerating external radioactivation. The WS measurement system consists of beam line actuators, a simple cable plant, an electronics processor chassis, and software located both in the electronics chassis (National Instruments LabVIEW) and in the Central Control Room (EPICS-based software). This WS measurement system will measure the more common H⁻ and H⁺ LANSCE-facility beams and will also measure less common beams. This paper describes these WS measurement systems.

MOPPR087	Transverse Beam Emittance Measurements of a 16 MeV Linac at the Idaho Accelerator Center	quadrupole, emittance, linac, background	990
	S. Setiniyaz, T.A. Forest ISU, Pocatello, Idaho, USA K. Chouffani, Y. Kim IAC, Pocatello, IDAHO, USA A. Freyberger JLAB, Newport News, Virginia, USA
	A beam emittance measurement of the 16 MeV S-band High Repetition Rate Linac (HRRL) was performed at Idaho State University's Idaho Accelerator Center (IAC). The HRRL linac structure was upgraded beyond the capabilities of a typical medical linac so it can achieve a repetition rate of 1 kHz. Measurements of the HRRL transverse beam emittance are underway that will be used to optimize the production of positrons using HRRL's intense electron beam on a tungsten converter. In this paper, we describe a beam imaging system using on an OTR screen and a digital CCD camera, a MATLAB tool to extract beamsize and emittance, detailed measurement procedures, and the measured transverse emittances for an arbitrary beam energy of 15 MeV.

MOPPR090	Progress Report on Development of a High Resolution Transverse Diagnostic based on Fiber Optics	diagnostics, radiation, photon, optics	996
	R. Tikhoplav, R.B. Agustsson, G. Andonian, A.Y. Murokh, S. Wu RadiaBeam, Santa Monica, USA R.K. Li, P. Musumeci, C.M. Scoby UCLA, Los Angeles, California, USA
	A beam profile monitor utilizing the technological advances in fiber optic manufacturing to obtain micron level resolution is under development at RadiaBeam Technologies. This fiber-optic profiling device would provide a low cost, turn-key solution with nominal operational supervision and requires minimal beamline real estate. Preliminary results of Cherenkov light generation in fiber is presented.

TUXA02	Upgrade Plans for the LHC Injector Complex	linac, injection, vacuum, feedback	1010
	R. Garoby, H. Damerau, S.S. Gilardoni, B. Goddard, K. Hanke, A.M. Lombardi, M. Meddahi, B. Mikulec, E.N. Shaposhnikova, M. Vretenar CERN, Geneva, Switzerland
	Challenging beams with much higher brightness than today are required for the LHC to achieve its high luminosity objective after the year 2020. It is the purpose of the LHC Injectors Upgrade (LIU) Project to achieve this result, consolidating and upgrading the existing set of ageing synchrotrons (PSB, PS and SPS), and using the new linac presently in construction (Linac4). The anticipated beam characteristics are described and compared to the known limitations in the different accelerators. The foreseen solutions are outlined as well as the planning for their implementation.
	Slides TUXA02 [72.367 MB]

TUYA02	Overview of Asymmetric Electron Hadron Colliders	collider, ion, hadron, proton	1025
	V. Ptitsyn BNL, Upton, Long Island, New York, USA
	The first lepton-proton collider HERA at DESY completed its operation in 2007. Presently, several accelerator proposals for future electron-hadron colliders are under consideration in several laboratories from all over the world. The future accelerators intend to exceed the HERA luminosity by 2-3 orders of magnitude, as well as to cover the different ranges of center-of-mass collision energies. The research capabilities will be extended by including the collisions of electrons with heavy ions, as well as, in some designs, with polarized protons and polarized ions. The future electron-hadron colliders would serve as high-resolution microscopes able to reveal unprecedented details of the structure of nucleons and ions, including their spin content and the state of high gluon density matter. The colliders will provide us with ultimate tools to test both the ways Quantum Chromodynamics works as well as to look for new physics beyond the Standard Model. All proposed electron-hadron colliders are based on the extension of existing accelerators to accommodate the electron-hadron collisions. Advanced accelerator technologies are utilized in order to achieve the desired high luminosity.
	Slides TUYA02 [6.002 MB]

TUXB01	Progress Towards Ultimate Storage Ring Light Sources	emittance, brightness, dipole, wiggler	1035
	M. Borland ANL, Argonne, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Developments such as the low emittance NSLS-II storage ring, followed by the even lower emittance MAX-IV ring, demonstrate that the technology of storage ring light sources has not reached full maturity. Indeed, these new sources are paving the way toward realizing diffraction-limited angstrom-wavelength storage ring light sources in the not-too-distant future. Our discussion begins with a review of recent trends and developments in storage ring design. We then survey on-going work around the world to develop concepts and designs for so-called "ultimate" storage ring light sources.
	Slides TUXB01 [3.442 MB]

TUXB02	Review of ERL Projects at KEK and Around the World	linac, gun, FEL, emittance	1040
	N. Nakamura KEK, Ibaraki, Japan
	Future synchrotron light sources based on energy-recovery linacs (ERLs) are expected to be capable of producing super-brilliant and/or ultra-short pulses of synchrotron radiation. The Japanese collaboration team is making efforts for realizing an ERL-based VUV and X-ray source with R&D efforts on super-conducting cavities and the electron gun at KEK and elsewhere. This presentation will describe the developments of the compact ERL project and the outline of the 3-GeV ERL light source project at KEK and also review ERL projects around the world, including potential applications to colliders.
	Slides TUXB02 [25.328 MB]

Paper

Title

Other Keywords

Page

MOYBP01

State-of-the-Art and Future Prospects in RF Superconductivity

cavity, SRF, niobium, storage-ring

11

K. Saito
KEK, Ibaraki, Japan

This presentation should recount the remarkable progress in improving the performance of superconducting cavities over the past 50 years and explore future directions, including advances in materials other than Nb, such as MgB2 and novel multi-layer superconductor-insulator systems. This talk should provide an overview of international activities.

Slides MOYBP01 [10.097 MB]

MOYCP01

Design and Simulation of IOTA - a Novel Concept of Integrable Optics Test Accelerator

focusing, betatron, optics, simulation

16

S. Nagaitsev, A. Valishev
Fermilab, Batavia, USA
V.V. Danilov
ORNL, Oak Ridge, Tennessee, USA
D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia

The use of nonlinear lattices with large betatron tune spreads can increase instability and space charge thresholds due to improved Landau damping. Unfortunately, the majority of nonlinear accelerator lattices turn out to be nonintegrable, producing chaotic motion and a complex network of stable and unstable resonances. Recent advances in finding the integrable nonlinear accelerator lattices have led to a proposal to construct at Fermilab a test accelerator with strong nonlinear focusing which avoids resonances and chaotic particle motion. This presentation will outline the main challenges, theoretical design solutions and construction status of the Integrable Optics Test Accelerator underway at Fermilab.

Slides MOYCP01 [2.816 MB]

MOOAA01

Performance of the Cornell High-Brightness, High-Power Electron Injector

cathode, gun, emittance, laser

20

B.M. Dunham, A.C. Bartnik, I.V. Bazarov, L. Cultrera, J. Dobbins, C.M. Gulliford, G.H. Hoffstaetter, R.P.K. Kaplan, V.O. Kostroun, Y. Li, M. Liepe, X. Liu, F. Löhl, P. Quigley, D.H. Rice, E.N. Smith, K.W. Smolenski, M. Tigner, V. Veshcherevich, Z. Zhao
CLASSE, Ithaca, New York, USA
S.S. Karkare, H. Li, J.M. Maxson
Cornell University, Ithaca, New York, USA

Funding: NSF DMR-0807731
The last year has seen significant progress in demonstrating the feasibility of a high current, high brightness photoinjector as required for the Energy Recovery Linac driven X-ray source at Cornell University. Both low emittances (0.4 mm-mrad rms normalized for 100% of the beam at 20 pC per bunch and 0.15 mm-mrad rms core emittance with 70% of the beam, and twice these values at 80 pC per bunch) and high average currents with a good lifetime well in excess of 1000 Coulombs at 5 MeV, 20 mA have been demonstrated. If these beams can be accelerated to 5 GeV without diluting the phase space, it would already provide a beam brightness higher than any existing storage ring. Operational experience, results, and the outlook for the future will be presented.

Slides MOOAA01 [1.424 MB]

MOOAA03

Fast Feedback Strategies for Longitudinal Beam Stabilization

feedback, controls, laser, free-electron-laser

26

S. Pfeiffer, M.K. Bock, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
W. Jałmużna
TUL-DMCS, Łódź, Poland
G. Lichtenberg, H. Werner
TUHH, Hamburg, Germany

The key for pump-probe and seeding experiments at Free Electron Lasers such as FLASH is a femtosecond precise regulation of the bunch arrival time and compression. To maintain this beam based requirements, both for a single bunch and within a bunch train, it is necessary to combine field and beam based feedback loops. We present in this paper an advancement of the currently implemented beam based feedback system at FLASH. The principle of beam based modulation of the RF set point can be superimposed by a direct feedback loop with a beam optimized controller. Recent measurements of the achieved bunch arrival time jitter reduction to 20 fs have shown the performance gain by this direct feedback method *. The combination of both approaches will be presented and possible advantages are discussed.
* C. Schmidt et al., “Feedback Strategies for Bunch Arrival Time Stabilization at FLASH Towards 10 fs,” FEL’2011, Shanghai, August 2011, THPA26, http://www. JACoW.org.

Slides MOOAA03 [0.544 MB]

MOOBA03

Development of a High-power Coherent THz Sources and THz-TDS System on the basis of a Compact Electron Linac

radiation, polarization, linac, laser

37

M. Kumaki, K. Sakaue, M. Washio
RISE, Tokyo, Japan
R. Kuroda, H. Toyokawa, K. Yamada
AIST, Tsukuba, Ibaraki, Japan

The high-power terahertz time-domain spectroscopy (THz-TDS) has been developed on the basis of a compact S-band electron linac at AIST, Japan. It is strongly expected for inspection of dangerous materials in the homeland security field. The linac consists of a photocathode rf-gun, two acceleration tubes and a magnetic bunch compressor. The 40 MeV, 1 nC electron bunch is generated and compressed to less than 1 ps. THz radiations are generated in two methods with the ultra-short bunch. One is THz coherent synchrotron radiation (CSR). The other is THz coherent transition radiation (CTR). In the preliminary experiment, it was observed that the focused CTR had the donut profile in a transverse fields due to its initial radial polarization, so that it made Z-polarization. In case of the THz-TDS experiment, CTR was controlled to linearly polarization with the polarizer and focused to an EO crystal to obtain a THz temporal waveform which leads to THz spectrum with Fourier transform. The timing measurement between CTR and a probe laser was realized with OTR using a same optical photodiode. In this conference, we will describe details of our linac and results of the THz-TDS experiment.

Slides MOOBA03 [3.342 MB]

MOOAB01

A Proton-driven Plasma Wakefield Accelerator Experiment with CERN SPS Bunches

plasma, proton, wakefield, acceleration

40

P. Muggli
MPI, Muenchen, Germany

Funding: Presented for the PDPWFA collaboration.
Existing relativistic proton (p⁺) bunches carry large amounts of energy (kJ) and are therefore attractive as drivers for plasma-based particle accelerators, such as the plasma wakefield accelerator or PWFA. However, short (~ps) p⁺ bunches capable of driving large amplitude (~GV/m) wakefields are not available today. It was recently proposed to use long (~300ps) p⁺ bunches self-modulated at the plasma wavelength by a transverse two-stream instability in a high-density (~10¹⁴-10¹⁵/cc) plasma to resonantly drive wakefields*. Based on this idea and on the long term prospect for short p⁺ bunches a p⁺-driven PWFA experimental program was proposed to study the acceleration of electrons to the TeV energy range. Initial experiments will use the 450GeV, 1-3·10¹¹ p⁺ bunches from the CERN SPS and plasmas 5-10m in length. The wakefields will be sampled by an externally injected, low energy (10-20MeV) electron bunch that will gain energy in the GeV range. The experimental plan, as well as the expected results will be presented.
*N. Kumar et al., Phys. Rev. Lett. 104, 255003 (2010).

Slides MOOAB01 [19.595 MB]

MOOAB02

First Results from the Electron Hose Instability Studies in FACET

plasma, acceleration, wakefield, status

43

E. Adli
University of Oslo, Oslo, Norway
W. An, C.E. Clayton, C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi
UCLA, Los Angeles, California, USA
S. Corde, R.J. England, J.T. Frederico, S.J. Gessner, M.J. Hogan, S.Z. Li, M.D. Litos, Z. Wu
SLAC, Menlo Park, California, USA
W. Lu
TUB, Beijing, People's Republic of China
P. Muggli
MPI, Muenchen, Germany

Funding: This work is supported by the Research Council of Norway and U.S. Department of Energy under contract number DE-AC02-76SF00515.
We present the first results from experimental studies of the electron hose instability in the plasma-wakefield acceleration experiments at FACET. Theory and PIC simulations of an electron beam as it travels through a plasma indicate that hosing may lead to a significant distortion of the transverse phase space. The FACET dump line is equipped with a Cherenkov light based spectrometer which can resolve transverse motion as a function of beam energy. We compare the predictions from simulations and theory to the experimental results obtained.

Slides MOOAB02 [4.654 MB]

MOOBB01

Transverse-to-longitudinal Emittance-exchange with an Energy Chirped Beam

emittance, cavity, simulation, radiation

49

J.C.T. Thangaraj, H.T. Edwards, A.S. Johnson, A.H. Lumpkin, T.J. Maxwell, J. Ruan, J.K. Santucci, Y.-E. Sun, R.M. Thurman-Keup
Fermilab, Batavia, USA

Emittance exchange has been proposed to increase the performance of free electron lasers by tailoring the phase space of an electron beam. The principle of emittance exchange - where the transverse phase space of the electron beam is exchanged with the longitudinal phase space - has been demonstrated recently at the A0 photoinjector. The experiment used a low charge bunch (250 pC) with no energy chirp. Theory predicts an improvement in the emittance exchange scheme when the incoming beam has an energy chirp imparted on it. The energy chirp helps to overcome the thick lens effect of the deflecting mode cavity and other second order effects that might lead to an incomplete emittance exchange at higher charges. In this work, we report experimental and simulation results from operating the emittance exchange beam line using an energy chirped beam with higher charge (500 pC) at different RF-chirp settings.

Slides MOOBB01 [2.338 MB]

MOOAC02

Status and Plans for a Superconducting RF Accelerator Test Facility at Fermilab

cryomodule, SRF, cryogenics, gun

58

J.R. Leibfritz, R. Andrews, C.M. Baffes, K. Carlson, B. Chase, M.D. Church, E.R. Harms, A.L. Klebaner, M.J. Kucera, A. Martinez, S. Nagaitsev, L.E. Nobrega, J. Reid, M. Wendt, S.J. Wesseln
Fermilab, Batavia, USA
P. Piot
Northern Illinois University, DeKalb, Illinois, USA

Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy.
The Advanced Superconducting Test Acccelerator (ASTA) is being constructed at Fermilab. The existing New Muon Lab (NML) building is being converted for this facility. The accelerator will consist of an electron gun, injector, beam acceleration section consisting of 3 TTF-type or ILC-type cryomodules, multiple downstream beamlines for testing diagnostics and conducting various beam tests, and a high power beam dump. When completed, it is envisioned that this facility will initially be capable of generating a 750 MeV electron beam with ILC beam intensity. An expansion of this facility was recently completed that will provide the capability to upgrade the accelerator to a total beam energy of 1.5 GeV. Two new buildings were also constructed adjacent to the ASTA facility to house a new cryogenic plant and multiple superconducting RF (SRF) cryomodule test stands. In addition to testing accelerator components, this facility will be used to test RF power systems, instrumentation, and control systems for future SRF accelerators such as the ILC and Project-X. This paper describes the current status and overall plans for this facility.

Slides MOOAC02 [13.423 MB]

MOEPPB002

The MICE Experiment

emittance, target, solenoid, coupling

76

A.P. Blondel
DPNC, Genève, Switzerland

Ionization Cooling is the only practical solution to preparing high brilliance muon beams for a neutrino factory or muon collider. The muon ionization cooling experiment (MICE) is under development at the Rutherford Appleton Laboratory (UK) by an international collaboration. The muon beam line has been commissioned and first measurements of emittance with particle physics detectors have been performed. The remaining apparatus is currently under construction. First results with a liquid-hydrogen absorber will be produced in 2013; a couple of years later a full cell of a representative ionization cooling channel, including RF re-acceleration, will be in operation. The design offers opportunities for tests with various absorbers and several optics configurations. Results will be compared with detailed simulations of cooling channel performance to ensure full understanding of the cooling process.
on behalf of the MICE collaboration

MOEPPB008

Simulation of Hollow Electron Beam Collimation in the Fermilab Tevatron Collider

simulation, collimation, quadrupole, collider

94

G. Stancari, I.A. Morozov, A. Valishev
Fermilab, Batavia, USA
D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia

Funding: Fermi Research Alliance, LLC operates Fermilab under Contract DE-AC02-07CH11359 with the US Department of Energy. This work was partially supported by the US LHC Accelerator Research Program (LARP).
The concept of augmenting the conventional collimation system of high-energy storage rings with a hollow electron beam was successfully demonstrated in experiments at the Tevatron. A reliable numerical model is required for understanding particle dynamics in the presence of a hollow beam collimator. Several models were developed to describe imperfections of the electron beam profile and alignment. The features of the imperfections are estimated from electron beam profile measurements. Numerical simulations of halo removal rates are compared with experimental data taken at the Tevatron.

MOEPPB014

Time Jitter Measurements in Presence of a Magnetic Chicane in the FERMI@elettra Linac

linac, FEL, laser, dipole

109

G. Penco, P. Craievich, S. Di Mitri, M.M. Milloch, F. Rossi
ELETTRA, Basovizza, Italy

Accurate and highly stable temporal synchronization between an electron bunch and a pulse from an external seed laser is one of the key requirements for successful operation of a seeded FEL in the XUV and soft x-ray regime. These requirements become more stringent when the electron bunch is longitudinally compressed to sub-ps durations in order to increase the current for more efficient FEL action. In this paper we present experimental measurements of the electron bunch arrival time jitter after the first magnetic compressor of FERMI@Elettra seeded FEL as a function of the compression factor. The experimental behavior of the pulse-to-pulse time jitter agrees both with results from tracking code simulations and with predictions from an analytical approach that takes into account the different sources of time jitter in FERMI, namely the photoinjector drive laser, the RF accelerating cavity phases and voltages, and fluctuations in the chicane bending magnet currents. We also present predictions for the expected arrival time jitter in the final configuration of FERMI that includes two bunch compressors and for which the synchronization requirement is of order 100 fs or better.

MOPPC001

Simulation of electron-cloud heat load for the cold arcs of the large hadron collider

simulation, dipole, injection, photon

115

G.H.I. Maury Cuna
CINVESTAV, Mérida, Mexico
G. Iadarola
Naples University Federico II, Science and Technology Pole, Napoli, Italy
G. Rumolo, F. Zimmermann
CERN, Geneva, Switzerland

The heat load due to the electron cloud in the Large Hadron Collider (LHC) cold arcs is a concern for its performance near and beyond nominal beam current. We report the results of simulation studies, which examine the electron-cloud induced heat load for different values of low-energy electron reflectivity and secondary emission yield at injection energy, as well as at beam energies of 4 TeV and 7 TeV, for two different bunch spacing: 25 ns and 50 ns. Benchmarking the simulations against heat-load observations at different beam energies and bunch spacing allows an estimate of the secondary emission yield in the cold arcs of the LHC and of its evolution as a function of time.

MOPPC009

Multipactor for E-cloud Diagnostics

resonance, cyclotron, vacuum, dipole

139

P. Costa Pinto, F. Caspers, P. Edwards, M. Holz, M. Taborelli
CERN, Geneva, Switzerland

Electron cloud in particle accelerators can be mitigated by coating the vacuum beam pipe with thin films of low secondary electron yield (SEY). SEY of small samples can be measured in the laboratory. Verifying the performance of long pipes is more complex, since it requires their insertion in the accelerator and the subsequent measurement of the beam induced pressure rise. RF induced multipacting in a coaxial waveguide configuration is proposed as a test before insertion in the machine. The technique is applied to two main bending dipoles of the SPS, where the RF power is fed though a tungsten wire stretched along the vacuum chamber (6.4 m). A dipole with a bare stainless steel chamber shows a clear power threshold initiating an abrupt rise in reflected power and pressure. The effect is enhanced at RF frequencies corresponding to cyclotron resonances for given magnetic field. Preliminary result show that the dipole with a carbon coated vacuum chamber does not exhibit any pressure rise or reflected RF power up to the maximum available input power. In the event of a large scale coating production this technique will be a valuable resource for quality control.

MOPPC019

Secondary Electron Yield Measurements of Fermilab’s Main Injector Vacuum Vessel

vacuum, gun, synchrotron, controls

166

D.J. Scott, D. Capista, K.L. Duel, R.M. Zwaska
Fermilab, Batavia, USA
S. Greenwald, W. Hartung, Y. Li, T.P. Moore, M.A. Palmer
CLASSE, Ithaca, New York, USA
R.E. Kirby, M.T.F. Pivi, L. Wang
SLAC, Menlo Park, California, USA

We discuss the progress made on a new installation in Fermilab’s Main Injector that will help investigate the electron cloud phenomenon by making direct measurements of the secondary electron yield (SEY) of samples irradiated in the accelerator. In the Project X upgrade the Main Injector will have its beam intensity increased by a factor of three compared to current operations. This may result in the beam being subject to instabilities from the electron cloud. Measured SEY values can be used to further constrain simulations and aid our extrapolation to Project X intensities. The SEY test-stand, developed in conjunction with Cornell and SLAC, is capable of measuring the SEY from samples using an incident electron beam when the samples are biased at different voltages. We present the design and manufacture of the test-stand and the results of initial laboratory tests on samples prior to installation.

MOPPC026

Simulations of Coherent Beam-Beam Effects with Head-on Compensation

resonance, proton, simulation, lattice

187

S.M. White, W. Fischer, Y. Luo
BNL, Upton, Long Island, New York, USA

Funding: Work partially supported by Brookhaven Science Associates, LARP, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Electron lenses are foreseen to be installed in RHIC in order to mitigate the head-on beam-beam effects. This would allow operation with higher bunch intensity and result in a significant increase in luminosity. We report on recent strong-strong simulations that were carried out using the RHIC upgrade parameters to assess the impact of coherent beam-beam effects in the presence of head-on compensation.

MOPPC036

Influence of Intense Beam in High Pressure Hydrogen Gas Filled RF Cavities

cavity, plasma, proton, pick-up

208

K. Yonehara, M.R. Jana, M.A. Leonova, A. Moretti, M. Popovic, T.A. Schwarz, A.V. Tollestrup
Fermilab, Batavia, USA
M. Chung
Handong Global University, Pohang, Republic of Korea
M.G. Collura
Politecnico di Torino, Torino, Italy
G. Flanagan, R.P. Johnson, M. Notani
Muons, Inc, Batavia, USA
B.T. Freemire, Y. Torun
IIT, Chicago, Illinois, USA

Funding: This work is supported by US DOE under contract DE-AC02-07CH11359.
Breakdown plasma in a high-pressure hydrogen gas filled RF cavity has been studied from a time domain spectroscopic light analysis. The observed breakdown plasma temperature and density reached 21,000 K and 10²⁰ cm^-3, respectively. The electron recombination rate has been evaluated from the decay of plasma density in various gas pressures. The recombination mechanism in dense plasma will be discussed. Finally, the similarity and difference of the breakdown processes between the high-pressure hydrogen gas filled RF cavity and a vacuum RF one will be discussed.

MOPPC037

Muon Collider Detector Backgrounds

collider, background, simulation, shielding

211

M.A.C. Cummings, S.A. Kahn
Muons, Inc, Batavia, USA
D. Hedin
Northern Illinois University, DeKalb, Illinois, USA
J.F. Kozminski
Lewis University, Romeoville, Illinois, USA

Funding: Supported in part by SBIR Grant 4738 · 10SC05447
Technological innovations in recent years have revived interest in muon colliders as the next generation energy frontier machine. Advances in muon cooling technology will make the focussing and acceleration of muons to TeV energies possible. The biggest challenge for muon colliders is that muons decay, but it is possible to build a large muon collider as a circular machine, even at multi-TeV energies, due to the greatly reduced synchrotron radiation expected from muons compared to electrons. The challenge for the detectors in such machines is overcoming the large backgrounds from muon decays in the colliding ring lattice that will inundate the interaction region (IR) and will make triggering and data reconstruction a challenge. Developing simulation tools that can reliably model the environment of the muon collider IR will be critical to physics analyses. We will need to expand the capabilities of current programs and use them to benchmark and verify results against each other. In this paper we will discuss these processes and calculate the resulting particle fluxes into the detector volume.

MOPPC038

Bethe-Heitler Muon Background at a Muon Collider

collider, background, hadron, simulation

214

S.A. Kahn, M.A.C. Cummings, T.J. Roberts
Muons, Inc, Batavia, USA
D. Hedin, A.O. Morris
Northern Illinois University, DeKalb, Illinois, USA
J.F. Kozminski
Lewis University, Romeoville, Illinois, USA

Multi-TeV muon colliders are an important option for a future energy frontier lepton collider since synchrotron radiation in a circular machine is significantly less than that in an electron collider. For a muon collider with 750 GeV μ+μ− with 2×10¹² μ per bunch we would expect 8.6×10⁵ muon decays per meter for the two beams. Muon decays are the source of beam induced backgrounds that can affect the physics. These backgrounds include electrons from muon decays, synchrotron radiation from the decay electrons, hadrons produced by photo-nuclear interactions, coherent and incoherent beam-beam pair production and Bethe-Heitler muon production. This paper will describe a simulation of the B-H muon pair production in a muon collider. These muons can penetrate the collider ring magnets and shielding and possibly enter into the detector regions. The simulation tracks B-H muons produced from electromagnetic shower interactions in collider ring material in the range of ±200 m from the interaction point.

MOPPC039

Electron Recombination in a Dense Hydrogen Plasma

cavity, collider, plasma, ion

217

B.T. Freemire, P.M. Hanlet
IIT, Chicago, Illinois, USA
M. Chung
Handong Global University, Pohang, Republic of Korea
M.G. Collura
Politecnico di Torino, Torino, Italy
M.R. Jana, C. Johnstone, T. Kobilarcik, G.M. Koizumi, M.A. Leonova, A. Moretti, M. Popovic, T.A. Schwarz, A.V. Tollestrup, Y. Torun, K. Yonehara
Fermilab, Batavia, USA
R.P. Johnson
Muons, Inc, Batavia, USA

Funding: US DOE under contract DE-AC02-07CH11359.
A high pressure hydrogen gas filled RF cavity was subjected to an intense proton beam to study the evolution of the beam induced plasma inside the cavity. The electron recombination rate with the dense ionized hydrogen plasma has been measured under varying conditions. Recombination rates as high as 10^-7 cm³/s have been recorded. This technique shows promise in the R&D program for a muon accelerator. The use of hydrogen, both as a way to prevent breakdown in an RF cavity and as a mechanism for cooling a beam of muons, will be discussed.

MOPPC040

Study of Electronegative Gas Effect in Beam-Induced Plasma

cavity, plasma, proton, ion

220

M.A. Leonova, M.R. Jana, A. Moretti, M. Popovic, T.A. Schwarz, A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, USA
M. Chung
Handong Global University, Pohang, Republic of Korea
M.G. Collura
Politecnico di Torino, Torino, Italy
B.T. Freemire, P.M. Hanlet, Y. Torun
IIT, Chicago, Illinois, USA
R.P. Johnson
Muons, Inc, Batavia, USA

Funding: This research was supported by US DOE under contract DE-AC02-07CH11359.
Muon Colliders and Neutrino Factories call for R&D for a high-gradient RF system capable of operating in a high magnetic field. Adding a high pressure gas inside an RF cavity (HPRF) prevents cavity breakdown, allowing higher gradients in a magnetic field. A high-energy beam passing through an HPRF cavity ionizes the gas, producing plasma. Plasma electrons absorb cavity’s energy, reducing the energy available for beam acceleration. Doping cavity gas with electronegative gas (gas that tends to attract and bond electrons) reduces the number of plasma electrons. The experiments were carried out at the MuCool Test Area (MTA) facility at Fermilab. Different concentrations of an electronegative gas SF6 were added to hydrogen gas. The results of room-temperature tests showing a great reduction in power drop in the cavity will be presented. However, a realistic cavity would operate at liquid nitrogen temperature, where SF6 freezes. Thus, a search for a better electronegative gas candidate is underway; we plan to test oxygen-doping next.

MOPPC045

Scaled Electron Model of a Dogbone Muon RLA with Multi-pass Arcs

linac, quadrupole, dipole, optics

235

S.A. Bogacz, A. Hutton, G.A. Krafft, V.S. Morozov, Y. Roblin
JLAB, Newport News, Virginia, USA
K.B. Beard, R.P. Johnson
Muons, Inc, Batavia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. Supported in part by USDOE STTR Grant DE-FG02-08ER86351.
The design of a dogbone RLA with linear-field multi-pass arcs was earlier developed for accelerating muons for a future Neutrino Factory and Muon Collider. It allows for efficient use of expensive RF while the multi-pass arc design based on linear combined-function magnets exhibits a number of advantages over single pass or pulsed arc designs. Such an RLA may have applications going beyond muon acceleration. This paper describes a possible straightforward test of this concept by scaling a GeV scale muon design for electrons. Scaling muon momenta by the muon-to-electron mass ratio leads to a scheme in which a 4.35 MeV/c electron beam is injected in the middle of a 2.9 MeV/pass linac with two double-pass return arcs, and is accelerated to 17.4 MeV/c in 4.5 passes. All spatial dimensions including the orbit distortion are scaled by a factor of 7.5, which arises from scaling the 200 MHz muon RF to a readily available 1.5 GHz. The footprint of a complete RLA fits in an area of 25 by 7 m. The scheme utilizes only fixed magnetic fields including injection and extraction. The hardware requirements are not very demanding, making it feasible to utilize the existing technologies.
The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

MOPPC049

Status of the Non-scaling Fixed Field Alternating Gradient Ring Design for the International Design Study of the Neutrino Factory

factory, acceleration, septum, lattice

241

J.S. Berg, H. Witte
BNL, Upton, Long Island, New York, USA
M. Aslaninejad, J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
N. Bliss, A.J. Moss
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
S.M. Pattalwar
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: This manuscript has been authored by employees of Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The International Design Study of the Neutrino Factory is working towards delivering the optimized design of the neutrino factory facility to be presented in the Reference Design Report (RDR) in 2013. In the current baseline design a linear non-scaling fixed field alternating gradient accelerator (FFAG) was chosen as an efficient solution for the final muon acceleration. We describe updates to the design since our previous report*. We report on beam dynamics studies on the lattice. We describe recent work on the engineering for the lattice, and the results of a recent first pass at a cost estimate for the machine. Finally, we describe how an FFAG may be applicable to a lower energy neutrino factory in light of recent experimental results regarding the value of the theta(13) neutrino mixing angle**.
* J. S. Berg et al., in Proceedings of IPAC2011, San Sebastian, Spain, 832.
** F. P. An et al., Phys. Rev. Lett. 10⁸, 171803 (2012); J. K. Ahn et al., arXiv:1204.0626v2 [hep-ex] (2012).

MOPPC052

Calculation of Synchrotron Radiation from High Intensity Electron Beam at eRHIC

photon, radiation, synchrotron, vacuum

247

Y.C. Jing, O.V. Chubar, V. Litvinenko
BNL, Upton, Long Island, New York, USA

The Electron-Relativistic Heavy Ion Collider (eRHIC) at Brookhaven National Lab adds an electron beam line to the existing RHIC and improves the luminosity by at least 2 orders of magnitude. It requires a high energy and high intensity electron beam. Thus the synchrotron radiation (SR) coming from the bending magnets and large quadrupoles could be penetrating the vacuum chamber and providing hazard to electronic devices and undesired background for detectors. In this paper, we calculate the SR spectral intensity and power density distributions on the chamber wall, suggest the wall thickness required to stop the SR, calculate heat load on the chamber, and estimate spectral characteristics of the residual and scattered background radiation outside the chamber.

MOPPC054

Multi-code Modelling of Momentum Collimation in the TRIUMF ARIEL Linac

gun, linac, simulation, TRIUMF

253

F.W. Jones, Y.-C. Chao, C. Gong
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

The electron linac component of the TRIUMF-ARIEL facility will provide CW beams of 50-75 MeV and up to 0.5 MW of beam power, with consequent requirements for low-loss operation. One factor in controlling beam quality is the reduction of the low-momentum tail arising from the rf-modulated 300 KV electron gun and initial capture elements prior to acceleration in the 10 MeV Injector linac. To study momentum collimation in the 10 MeV transfer line to the main linac, and its implications for downstream beam characteristics, a simulation model has been constructed using several tracking and optics codes, linked together by scripts and data converters. The model follows the evolution of the beam from the e-gun through the injector cryo-module and the medium energy transfer line where the proposed collimator is located. The components, methods and results of this application are described in detail.

MOPPC060

Investigations into Beam Life Time in Low Energy Storage Rings

ion, target, storage-ring, antiproton

271

A.I. Papash, A.V. Smirnov
MPI-K, Heidelberg, Germany
A.I. Papash
JINR, Dubna, Moscow Region, Russia
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: Work supported by the Helmholtz Association of National Research Centers and GSI under contract VH-NG-328.
In low energy storage rings, beam life time critically depends on the residual gas pressure, scattering effects caused by in-ring experiments and the available machine acceptance. A comprehensive simulation study into these effects has been realized with a focus on the TSR storage ring in Heidelberg and the electrostatic rings ELISA, the AD recycler and the ultra-low energy storage ring (USR). This was done by using the computer code BETACOOL in combination with the OPERA-3D and MAD-X programs. In this contribution, the results from these studies are presented and compared to available experimental data. Based on these simulations, criteria for stable ring operation are then presented.

MOPPC063

Computation of the 2D Transverse Wake Function of an Electron Cloud for Different Parameters

simulation, dipole, lattice, wakefield

280

A. Markoviḱ, G. Pöplau, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany

Funding: Work supported by DFG under contract number RI 814/20-2.
A PIC simulation of the interaction of a positive charged bunch with an e-cloud yields the wake kick from the electrons on the tail particles of the bunch. The wake is induced from a certain offset in the transverse position of the head parts of the bunch which perturb the electron distribution. Such a pre-computed wake functions of each offset part of the bunch are forming a matrix which could be used for investigating single bunch stability under several assumptions. In this paper we investigate the linear scalability of the kick with the offset value. Furthermore we investigate the wake values for different realistic electron densities. Another important parameter for realizing the single bunch stability simulation is the optimal number of bunch slices in longitudinal direction. Here we study the thickness of the slices in conjunction with the mobility of the electrons around the beam axis.

MOPPC064

Simulation of the Behavior of Ionized Residual Gas in the Field of Electrodes

ion, simulation, emittance, vacuum

283

G. Pöplau, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
A. Meseck
HZB, Berlin, Germany

Funding: Work supported by BMBF under contract number 05K10HRC
Light sources of the next generation such as ERLs require minimal beam losses as well as a stable beam position and emittance over the time. Instabilities caused by ionized residual gas have to be avoided. In this paper we present simulations of the behavior of ionized residual gas in the field of clearing electrodes and investigate e.g. clearing times. For these simulations we apply MOEVE PIC Tracking developed at Rostock University. We demonstrate numerical results with parameters planed for the ERL BERLinPro.

MOPPC066

A Design of Thermionic Electron Gun for Traveling Wave Electron-linac in order to Inject Beam into Booster Synchrotron Accelerator

gun, cathode, simulation, synchrotron

286

S. Ahmadian, F. AbbasiDavani, F. Ghasemi, M.Sh. Shafiee
sbu, Tehran, Iran

Applying computational codes functioning on the basis of methods such as Finite Integration caused the designing of different parts of an accelerator to be done faster and with more precision. The first step in using new software is the validation of these codes by experimental results, analytic relations or validating them against other codes whose validity has already been proved. This research aims to design an appropriate structure for thermionic electron gun of traveling wave electron-linac to be used to inject beam into synchrotron accelerators. Firstly, a simple structure of an electron gun used in TWT tube was simulated, and the parameters such as current, perveance, waist beam position, waist beam radius, beam radius entering anode aperture, and also the electric potential variation in the anode-cathode distance and the electric field of anode aperture were compared by experimental results and analytic relations. After verifying the software accuracy, a design for an electron gun with energy and current respectively 200 keV, 18 A and also initial beam radius of 8mm and minimum beam radius of 2.4 mm situated at the distance of 67.44mm from the cathode, was presented.

MOPPC067

Design and Construction of Inductive BPM

simulation, impedance, vacuum, resonance

289

M.Sh. Shafiee, E.E. Ebrahimibasabi, S.A.H. Feghhi, N. Goudarzi
sbu, Tehran, Iran
M. Jafarzadeh
ILSF, Tehran, Iran

To have a controllable Electron machine, that is required to be able to control beam orbits by knowing the beam position. The basic requirement for detecting the position of electron is calibrating and testing the BPMs. For this purpose wire method is used. Since we hadn't access to accelerator, for having experience at beam diagnostic we used this method for testing our constructed inductive BPM including 4 cm square poly ethylene core with 15 turns coil in each side. In this case study that was tested by a pulsed current (as an electron bunch) produced by a pulse generator. At first Tektronix 2235A oscilloscope was calibrated and used to measure the induced voltage of each coils, then by using of microcontroller, protocol RS232 and GUI induced voltages were read. The electrical center was measured with respect to the mechanical center and wire position was detected with 1mm Resolution. Conversion between the BPM signals and the actual wire position were done. Results were compared and presented.

MOPPC070

Field Emission Simulation for KEK-ERL 9-Cell Superconducting Cavity

cavity, simulation, linac, coupling

295

E. Cenni
Sokendai, Ibaraki, Japan
T. Furuya, H. Sakai, M. Satoh, K. Shinoe, K. Umemori
KEK, Ibaraki, Japan
M. Sawamura
JAEA/ERL, Ibaraki, Japan

In order to develop the Energy Recovery Linac at KEK, we are studying the performance of L-band superconducting cavities by means of vertical tests. One of the limiting factor for the cavities performance is power losses due to field emitted electrons. With regard to this phenomena, a particle tracking code is used to study electron trajectories and deposited energy on the inner surface of the cavity. Different emitters location were tested within a range of accelerating field and phases in order to reproduce different scenario. The final goal of this study is to locate the sources of the electrons inside the cavity through a deeper understanding of the phenomena. To validate the results from the simulation the outcome data are compared with other particle tracking codes.

MOPPC075

A Generic Data Model for HeadTail: Design and Implementation with Examples

simulation, HOM, wakefield, collective-effects

307

K.S.B. Li, G. Rumolo
CERN, Geneva, Switzerland

HeadTail has been developed in 2002 for the efficient simulation of instabilities and collective effects in large circular accelerators. Since then, the capabilities of the code have been continuously extended and the output data has become increasingly complex and large-scale ranging from the statistical description of single bunches to the statistical description of all slices within bunches up to the dynamics of the full 6D phase space over several thousands of turns. Processing this data in an effective manner and endowing it with a structure that provides a physical concept calls for new and optimised data formats. To meet state-of-the-art standards, the hierarchical data format (HDF5) has been selected as native output data format together with H5Part and XDMF as native data structures. We describe the implementation of the H5Part and the XDMF data structures into HeadTail and show some illustrative examples for data processing.

MOPPC079

Modelling of the EMMA ns-FFAG Ring Using GPT

space-charge, emittance, injection, quadrupole

319

R.T.P. D'Arcy, S. Jolly
UCL, London, United Kingdom
J.K. Jones, B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S.B. van der Geer
Pulsar Physics, Eindhoven, The Netherlands

EMMA (Electron Machine with Many Applications) is a prototype non-scaling Fixed-Field Alternating Gradient (ns-FFAG) accelerator whose construction at Daresbury Laboratory, UK, was completed in the autumn of 2010. The energy recovery linac ALICE will serve as an injector for EMMA, within an energy range of 10 to 20 MeV. The injection line consists of a symmetric 30 degree dogleg to extract the beam from ALICE, a matching section and a tomography section for transverse emittance measurements. This is followed by a transport section to the injection point of the EMMA ring. The ring is composed of 42 cells, each containing one focusing and one defocusing quadrupole. Acceleration over many turns of the EMMA machine has recently been confirmed. In some cases the bunch will traverse upwards of 100 turns, at which point the effects of space-charge may be significant. It is therefore necessary to model the electron beam transport in the ring using a code capable of both calculating the effect of and compensating for space-charge. Therefore the General Particle Tracer (GPT) code has been used. A range of injection beam parameters have been modeled for comparison with experimental results.

MOPPC081

Simulation of RF Cavity Dark Current in Presence of Helical Magnetic Field

cavity, simulation, dipole, site

325

G.V. Romanov, V.S. Kashikhin
Fermilab, Batavia, USA

In order to produce muon beam of high enough quality to be used for a Muon Collider, its large phase space must be cooled several orders of magnitude. This task can be accomplished by ionization cooling. Ionization cooling consists of passing a high-emittance muon beam alternately through regions of low-Z material, such as liquid hydrogen, and very high accelerating RF cavities within a multi-Tesla solenoidal focusing channel. But first high power tests of an RF cavity with beryllium windows in a solenoidal magnetic field showed a dramatic drop in accelerating gradient due to RF breakdowns. It has been concluded that external magnetic fields parallel to the RF electric field significantly modifies the performance of RF cavities. However, the magnetic field in a Helical Cooling Channel has a strong dipole component in addition to a solenoidal one. The dipole component essentially changes electron motion in a cavity compared to a pure solenoidal case, making dark current less focused at field emission sites. The simulation of a dark current dynamic in HCC performed with CST Studio Suite is presented in this paper.

MOPPC084

G4beamline Code Development

space-charge, collider, radiation, synchrotron

334

T.J. Roberts
Muons, Inc, Batavia, USA

Funding: Supported in part by DoE STTR grant DE-FG02-06ER86281.
G4beamline is a single-particle-tracking simulation program based on Geant4, optimized specifically for beam lines. It is currently used by several hundred physicists and designers around the world, who apply it to a diverse set of interesting problems. As it includes particle decays and interactions, it is applicable to beams for which decays and interactions are important, such as modern muon facilities that involve ionization cooling. Its description language has been designed to be both versatile and user-friendly, and the program includes high-quality visualization and histogramming capabilities. This paper discusses recent code development and new features, and some interesting applications of the program. G4beamline is an open-source program freely available at http://g4beamline.muonsinc.com

MOPPC090

Coupling Modulator Simulations into an FEL Amplifier for Coherent Electron Cooling

FEL, simulation, radiation, positron

346

I.V. Pogorelov, G.I. Bell, D.L. Bruhwiler, B.T. Schwartz, S.D. Webb
Tech-X, Boulder, Colorado, USA
Y. Hao, V. Litvinenko, G. Wang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by the US DOE Office of Science, Office of Nuclear Physics under grant numbers DE-FG02-08ER85182 and DE-SC0000835.
Next-generation ion colliders will require effective cooling of high-energy hadron beams. Coherent electron cooling (CeC) can in principle cool relativistic hadron beams on orders-of-magnitude shorter time scales than other techniques*. Particle-in-cell (PIC) simulations of a CeC modulator with the parallel VORPAL framework generate macro-particle distributions with subtle but important phase space correlations. To couple these macro-particles into a 3D simulation code for the free-electron laser (FEL) amplifier, while retaining all details of the 6D phase space coordinates, we implemented an alternative approach based on particle-clone pairs**. Our approach allows for self-consistent treatment of shot noise and spontaneous radiation, with no need for quiet-start initialization of the FEL macro-particles' ponderomotive phase. We present results of comparing fully 3D amplifier modeling based on the particle-clone approach vs GENESIS simulations where distribution of bunching parameter was used as input. We also discuss enabling direct coupling of the VORPAL delta-f simulation output into 3D distributions of particle-clone pairs.
* V.N. Litvinenko and Y.S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009).
** V.N. Litvinenko, "Macro-particle FEL model with self-consistent spontaneous radiation," unpublished (2002).

MOPPC093

Optimal Fast Multipole Method Data Structures

target, multipole, simulation, space-charge

352

S. Abeyratne, B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA
S.L. Manikonda
ANL, Argonne, USA

The Fast Multipole Method (FMM) has been identified as one of the ten most significant numerical algorithms discovered in the 20th century. The FMM guarantees finding fast solutions to many problems in science, such as calculating Coulomb potentials among large number of particles by reducing memory footprint and run time while attaining very high accuracy levels. One important practical issue that we have to solve in implementing a FMM algorithm is organizing large amounts of data, also called data structuring. The non-adaptive FMM is appropriate when the particles are uniformly distributed while the adaptive FMM is most efficient when the distribution is non-uniform. In practice, we typically encounter highly non-uniform 3D particle distributions. This paper summarizes our implementation of a 3D adaptive FMM algorithm data structure setup for non-uniform particle distributions.

MOPPC094

Charge Density Estimations with Orthogonal Polynomials

space-charge

355

D. Hernandez, B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA

Funding: This work was supported by the Department of Energy under Contract No. DE-FG02-08ER41532 with Northern Illinois University.
A beam’s charge density, treated as a smooth and continuous function can be approximated using orthogonal series, allowing a solution of Poisson’s equation to be found. Getting the most accurate solution to the electric potential requires the best approximated charge density. Several beam distributions are approximated using Jacobi polynomials generated by the recursion relation and the moment method. Varying both the particle number and order of the approximation gives a chance to not only compare the performance of the different polynomials, but allows to determine if a particular combination of order and particle number works better for a particular function. Although all three orthogonal polynomials used give similar results, the approximation coefficients should be allowed to converge and taken to high orders for best results. This is clearly seen on the single Gaussian approximation, where after five million particles, the difference between the distributions remains constant and the highest tested order gives best results.

MOPPD006

Commissioning of the 2MeV Electron Cooler for COSY / HESR

high-voltage, solenoid, gun, laser

379

V. Kamerdzhiev, J. Dietrich
FZJ, Jülich, Germany
V.N. Bocharov, M.I. Bryzgunov, A.D. Goncharov, V.M. Panasyuk, V.V. Parkhomchuk, V.B. Reva, D.N. Skorobogatov
BINP SB RAS, Novosibirsk, Russia

The new electron cooler for COSY is built at BINP Novosibirsk. Electron beam commissioning is in progress. Installation in COSY and commissioning with proton beam is scheduled for the beginning of 2012. Beam cooling with up to 3 A of electron current at up to 2 MeV is expected to boost the luminosity in the entire energy range of COSY by counteracting the effects caused by dense targets interacting with the circulating beam. Furthermore, the 2 MeV electron cooler can be used for beam cooling at injection energy in the HESR ring in the FAIR project. The electron beam is guided by a solenoidal magnetic field all the way from the electron gun to the collector. A cascade transformer provides power to numerous high voltage sections, short solenoids, and the collector inside a pressure vessel filed with SF6 gas. Commissioning results are reported.

MOPPD007

Towards Routine Operation of the Scintillation Profile Monitor at COSY

vacuum, injection, synchrotron, proton

382

V. Kamerdzhiev, J. Dietrich, K. Reimers
FZJ, Jülich, Germany
C. Böhme
ESS, Lund, Sweden
A. Pernizki
INP, Jülich, Germany

The optics of the Scintillation Profile Monitor (SPM) was modified to correct the large error observed in previous measurements. Beam profile measurements were carried out after reinstallation in the COSY ring, showing reasonable agreement with profiles, measured with the ionization profile monitor. Performance of the SPM is analyzed. Application of the method in a proton synchrotron is discussed.

MOPPD016

Status of Proof-of-principle Experiment for Coherent Electron Cooling

gun, ion, wiggler, FEL

400

I. Pinayev, S.A. Belomestnykh, I. Ben-Zvi, J. Bengtsson, A. Elizarov, A.V. Fedotov, D.M. Gassner, Y. Hao, D. Kayran, V. Litvinenko, G.J. Mahler, W. Meng, T. Roser, B. Sheehy, R. Than, J.E. Tuozzolo, G. Wang, S.D. Webb, V. Yakimenko
BNL, Upton, Long Island, New York, USA
G.I. Bell, D.L. Bruhwiler, V.H. Ranjbar, B.T. Schwartz
Tech-X, Boulder, Colorado, USA
A. Hutton, G.A. Krafft, M. Poelker, R.A. Rimmer
JLAB, Newport News, Virginia, USA
M.A. Kholopov, P. Vobly
BINP SB RAS, Novosibirsk, Russia

Funding: US DOE Office of Science, DE-FC02-07ER41499, DE-FG02-08ER85182; NERSC DOE contract No. DE-AC02-05CH11231.
Coherent electron cooling (CEC) has a potential to significantly boost luminosity of high-energy, high-intensity hadron colliders. To verify the concept we conduct proof-of-the-principle experiment at RHIC. In this paper, we describe the current experimental setup to be installed into 2 o’clock RHIC interaction regions. We present current design, status of equipment acquisition and estimates for the expected beam parameters.

MOPPD029

Recent Achievements and Upgrade Programs at RIKEN Radioactive Isotope Beam Factory

ion, cyclotron, ECRIS, linac

430

H. Okuno, T. Dantsuka, M. Fujimaki, T. Fujinawa, N. Fukunishi, H. Hasebe, Y. Higurashi, K. Ikegami, E. Ikezawa, H. Imao, T. Kageyama, O. Kamigaito, M. Kase, M. Kidera, M. Komiyama, H. Kuboki, K. Kumagai, T. Maie, M. Nagase, T. Nakagawa, M. Nakamura, J. Ohnishi, N. Sakamoto, K. Suda, H. Watanabe, T. Watanabe, Y. Watanabe, K. Yamada, H. Yamasawa
RIKEN Nishina Center, Wako, Japan

Recent achievements and upgrade programs in the near future at RIKEN Radioactive Isotope Beam Factory (RIBF) are presented. The beam intensity and available ion species are increasing at RIBF, owing to the continuous efforts that have been paid since the first beam in 2006. So far, we accelerated deuteron, helium, nitrogen, oxygen, aluminum, calcium, krypton, and uranium beams with the world's first superconducting ring cyclotron, SRC*. The extracted beam intensities reached 1,000 pnA for helium and oxygen beams. From the operational point of view, however, the intensity of the uranium beam should be much increased. Therefore we constructed a new injector system for the RIBF, consisting of a 28 GHz ECR ion sources, RFQ and DTL, which was successfully commissioned in the end of 2010. Furthermore we developed low-Z (low atomic number Z) gas stripper** alternative to standard carbon foil stripping, which will be reliable and efficient charge stripping scheme for such high-power uranium beams.
* H. Okuno et al., IEEE Trans. Appl. Supercond., 18, 226 (2008).
** H. Okuno et al., Phys. Rev. ST Accel. Beams 14, 033503 (2011).

MOPPD038

Simulation Study of Electron Response Amplification in Coherent Electron Cooling

ion, bunching, FEL, undulator

448

Y. Hao, V. Litvinenko
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In Coherent Electron Cooling (CEC), it is essential to study the amplification of electron response to a single ion in the FEL process, in order to proper align the electron beam and the ion beam in the kicker to maximize the cooling effect. In this paper, we use Genesis to simulate the amplified electron beam response of single ion in FEL amplification process, which acts as 'Green function' of the FEL amplifier.

MOPPD043

Novel Muon Beam Facilities for Project X at Fermilab

proton, target, dipole, linac

457

C.M. Ankenbrandt, R.J. Abrams, T.J. Roberts, C. Y. Yoshikawa
Muons, Inc, Batavia, USA
D.V. Neuffer
Fermilab, Batavia, USA

Innovative muon beam concepts for intensity-frontier experiments such as muon-to-electron conversion are described. Elaborating upon a previous single-beam idea, we have developed a design concept for a system to generate four high quality, low-energy muon beams (two of each sign) from a single beam of protons. As a first step, the production of pions by 1 and 3 GeV protons from the proposed Project X linac at Fermilab is being simulated and compared with the 8-GeV results from the previous study.

MOPPD046

Lifetime of the Highly Efficient H⁻ Ion Sources

cathode, ion, plasma, extraction

466

V.G. Dudnikov
Muons, Inc, Batavia, USA
D.S. Bollinger
Fermilab, Batavia, USA
D.C. Faircloth, S.R. Lawrie
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

Funding: Work supported by grant DE-SC0006267, and STFC JAI grant ST/G008531
Factors limiting operating lifetime of Compact Surface Plasma Sources (CSPS) are analyzed and possible treatments for lifetime enhancement are considered. CSPSs have high plasma density (up to 10¹⁴ cm^-3), high emission current density of negative ions (up to 8 A/cm²), small (1–5 mm) gap between cathode emitter, and a small extraction aperture in the anode. They are very simple, have high energy efficiency up to 100 mA/kW of discharge (~100 times higher then modern large Volume RF SPS) and have a high gas efficiency (up to 30%) using pulsed valves. CSPSs are very good for pulsed operation but electrode power density is often too high for dc operation. However, CSPSs were successfully adopted for DC operation with emission current density ~300 mA/cm² in Hollow cathode Penning Discharge and up to 1 A/cm² in Spherical focusing semiplanotron. Flakes from electrodes sputtering and blistering induced by back accelerated positive ions are the main reasons of ion source failure. Suppression of back accelerated positive ions, flakes explosion by pulsed discharges, and flakes gasification by discharge in NF₃ (or XeF₂) can be used for significant increase of operating lifetime of CSPSs.

MOPPD047

Progress of Surface Plasma H⁻ Ion Source with Saddle RF Antenna Plasma Generator

plasma, ion, ion-source, gun

469

V.G. Dudnikov, R.P. Johnson
Muons, Inc, Batavia, USA
S.N. Murray, T.R. Pennisi, C. Piller, M. Santana, M.P. Stockli, R.F. Welton
ORNL, Oak Ridge, Tennessee, USA

Funding: Supported in part by SBIR Grant 4729 · 09SC02690.
Progress in development of RF H⁻ surface plasma source (SPS) with saddle (SA) RF antenna which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability will be considered. Several versions of new plasma generators with a small Al2O3chamber and different antennas and magnetic field configurations were tested in the SNS small Test Stand. A prototype SA SPS was installed in the Test Stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency of 1.6 mA/kW. Control experiments with H⁻ beam produced by SNS SPS with internal and external antennas in the similar conditions were conducted. A new version of the RF triggering plasma source (TPS) has been designed and fabricated. A Saddle antenna SPS with water cooling is being fabricated for high duty factor testing

MOPPD048

Ribbon Electron Beam Profile Monitor for Bunched Beam Tomography

cathode, proton, ion, diagnostics

472

V.G. Dudnikov
Muons, Inc, Batavia, USA
A.V. Aleksandrov
ORNL, Oak Ridge, Tennessee, USA

Funding: Work supported by Contract DE-AC05-00OR22725 and by STTR grant DE-SC0007559
Advanced beam diagnostics are essential for high performance accelerator beam production and for reliable accelerator operation. It is important to have noninvasive diagnostics which can be used continuously with intense beams of accelerated particles. Recently, an electron probe was successfully used to determine accelerated particle density distributions. However, the apparatus used for this diagnostic is large and complex which restricts its wider use for tomography of accelerated bunches. We propose to use a strip cathode is for ribbon electron beam formation instead of a scanning of pencil beam used in the previous electron probe bunch profile monitors. The apparatus with the strip cathode is smaller, has simpler design and less expensive manufacturing, can have better magnetic shielding, higher sensitivity, higher resolution, can have better measurement accuracy and better time resolution. With this device it is possible to develop almost ideal tomography diagnostics of bunches in linear accelerators and in circular accelerators and storage rings.

MOPPD063

A 180 MeV Injection System for the ISIS Synchrotron

injection, dipole, synchrotron, simulation

511

B. Jones, D.J. Adams, M.C. Hughes, S.J.S. Jago, H. V. Smith, C.M. Warsop, R.E. Williamson
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The ISIS Facility at the Rutherford Appleton Laboratory in the UK produces intense neutron and muon beams for condensed matter research. It operates at 50 Hz accelerating 3x10¹³ protons per pulse via a 70 MeV H⁻ linac and an 800 MeV proton synchrotron, delivering a mean beam power of 0.2 MW. A favoured first step to upgrade ISIS towards the megawatt regime is replacement of the linac with a new 180 MeV injector. Studies of this upgrade, which aims to increase mean beam power up to 0.5 MW are continuing. This paper summarises designs for a new injection region including beam dynamics and related hardware.

MOPPD069

Challenges for the SNS Ring Energy Upgrade

injection, kicker, septum, extraction

520

M.A. Plum, T.V. Gorlov, J.A. Holmes, T. Hunter, R.T. Roseberry, J. G. Wang
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725.
The Oak Ridge Spallation Neutron Source accumulator ring presently operates at a beam power of about 1 MW and a beam energy of 925 MeV. A power upgrade is planned to increase the beam energy to 1.3 GeV. For the accumulator ring this mostly involves modifications to the injection and extraction sections. A variety of modifications to the existing injection section were necessary to achieve 1 MW, and the tools developed and the lessons learned from this work are now being applied to the design of the new injection section. This paper will discuss the tools and the lessons learned, and also present the design and status of the upgrades to the accumulator ring.

MOPPD073

Development of Transportation System for Low Energy Electron Group

solenoid, collimation, simulation, injection

532

S. Kato
Tohoku University, Graduate School of Science, Sendai, Japan
M. Kinsho, K. Yamamoto, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

There is a time that we want to measure the electron which occurred in the accelerator in the small situation of a noise. In that case, it is one method that we transport these electrons to the place distant form the accelerator where a noise is small. In order to realize that, development of transport line for low energy electrons is required. So, we start to develop transport line using solenoid magnets. We present status of development of this transportation system.

MOPPP003

Comparison of Various Sources of Coherent THz Radiation at FLUTE

radiation, synchrotron, linac, synchrotron-radiation

568

M. Schwarz, E. Huttel, A.-S. Müller, S. Naknaimueang, M.J. Nasse, R. Rossmanith, M. Schuh, P. Wesolowski
KIT, Karlsruhe, Germany
M.T. Schmelling
MPI-K, Heidelberg, Germany

The "Ferninfrarot Linac- Und Test-Experiment" FLUTE, based on a 50 MeV S-band linac with bunch compressor, is currently under construction at the KIT in Karlsruhe in order to study the production of coherent radiation in the Terahertz frequency range. The three photon generating mechanisms investigated in this paper are coherent synchrotron-, edge-, and transition radiation. For each case, we present the spectra and peak electric fields calculated from longitudinal charge distributions of a short, low charge and a long, high charge bunch. The respective bunch shapes are obtained by a detailed simulation (particle tracking) of FLUTE. We also give the expected temporal evolution of the electric field pulses.

MOPPP004

Further Study on Fast Cooling in Compton Storage Rings

laser, storage-ring, simulation, photon

571

E.V. Bulyak
NSC/KIPT, Kharkov, Ukraine
J. Urakawa
KEK, Ibaraki, Japan
F. Zimmermann
CERN, Geneva, Switzerland

Compton sources can produce gamma-ray photons of ultimate intensity, but suffer from the large recoils experienced by the circulating electrons scattering off the laser photons. We have previously proposed a scheme called asymmetric fast cooling to reduce the beam energy spread in Compton rings. This report presents results of further studies on the fast cooling. In particular, we show that (1) a proper asymmetric setup of the scattering point results in significant reduction of the quantum losses of electrons in Compton rings with moderate energy acceptance, and (2) the optimized pulsed mode of operation in synchrotron-dominated rings enhances the overall performance of such gamma-ray sources. Theoretical results presented are in good accordance with numerical simulations. We discuss the performance of an existing storage ring such as KEK ATF DR equipped with an optical cavity and presently available laser system.

MOPPP005

Feasibility of THz Source Based on Coherent Smith-Purcell Radiation Generated by Femtosecond Electron Bunches in Super-Radiant Regime

radiation, simulation, laser, gun

574

L.G. Sukhikh, K.P. Artyomov, A. Potylitsyn
Tomsk Polytechnic University, Tomsk, Russia
A.S. Aryshev, J. Urakawa
KEK, Ibaraki, Japan
V. Karataev
JAI, Egham, Surrey, United Kingdom

Nowadays there is a big interest to THz radiation that is a promising tool for investigations in material science, in biology, medicine and other fields. THz radiation for users is mostly produced by Light Sources that are big and complex machines. Because of this there are numerous activities in research and development of a compact THz source. One of the trends is based on using different types of radiation generated in coherent regime by short electron bunches. The promising radiation mechanism is coherent Smith-Purcell radiation (CSPR) that has monochromatic angular distribution and that is generated while the bunch travels in a vicinity of a grating. In this report we present simulated characteristics of frequency-locked coherent Smith-Purcell radiation (super-radiant regime) generated by a train of short (hundreds of femtosecond) 10 MeV electron bunches with THz spacing. The simulations are performed for different grating profiles and parameters using existing CSPR models and Particle-in-Cell simulation code. We also discuss the feasibility of the THz source based on CSPR and status of the experiment that is prepared at LUCX facility at KEK after the upgrade.

MOPPP006

Inverse Cherenkov Radiation based on Smith-Purcell Effect

radiation, linac, gun, laser

577

K. Kan, T. Kondoh, K. Norizawa, A. Ogata, J. Yang, Y. Yoshida
ISIR, Osaka, Japan
M. Hangyo
ILE Osaka, Suita, Japan
R. Kuroda, H. Toyokawa
AIST, Tsukuba, Ibaraki, Japan

Inverse Cherenkov radiation based on Smith-Purcell effect using metamaterial was investigated. A metallic grating and picosecond electron bunch of 27 MeV beam energy from a thermionic DC gun and linac were used for the inverse radiation. The frequency spectra in terahertz (THz) range were measured by a Michelson interferometer experimentally. Peaks of discrete component in the spectra shifted continuously according to the radiation angles, e. g. discrete peak changing from 0.117 to 0.085 THz with radiation angle along the electron bunch from 102 to 134 degree (backward) using a 2-mm-period metallic grating. In this presentation, experiment using another electron bunch generated by a photocathode RF gun linac will be reported.

MOPPP007

High-intensity Monochromatic Cherenkov Radiation in THz Range by Femtosecond Electron Bunches in Impurity-doped Semiconductor Tube

radiation, plasma, wakefield, vacuum

580

A. Ogata, K. Kan, T. Kondoh, K. Norizawa, J. Yang, Y. Yoshida
ISIR, Osaka, Japan

A novel method to generate high-power THz radiation is proposed and the preliminary experiments are conducted. If a beam with a bunch length on the order of 100 fs is injected into an electron–hole plasma of a semiconductor with a plasma frequency on the order of THz, THz wake fields are coherently generated. If the beam moves on the axis of a hollow tube covered by a metal, the frequency spectrum of the radiation is composed of discrete components. Monochromatic radiation is obtained by making only the lowest frequency component coherent. In the preliminary experiments using mm-sized dielectric tubes, the radiation spectra, which was driven by electron bunches of 200fs/27 MeV, were measured directly by a Michelson interferometer and bolometer. Peaks at frequencies of 0.09 and 0.14 THz of transverse magnetic (TM) modes, which corresponded to TM03 and TM04, were observed. The other higher modes, e. g. 0.36 (TM09) and 0.40 THz (TM010), were also observed successfully at a bunch charge of 15 pC, which decreased the electron bunch length.

MOPPP008

Hard X-ray Generation Experiment at Tsinghua Thomson Scattering X-Ray Source

laser, photon, scattering, background

583

Y.-C. Du, H. Chen, Q. Du, Hua, J.F. Hua, W.-H. Huang, H.J. Qian, C.-X. Tang, H.S. Xu, L.X. Yan, Z. Zhang
TUB, Beijing, People's Republic of China

Recently, there is increasing industrial and scientific interesting in ultra-fast, high peak brightness, tunable energy and polarization, monochromatic hard X-ray source. The X-ray source based on the Thomson scattering between the relativistic electron beam and TW laser pulse is the suitable candidate for its compact and affordable alternatives for high brightness hard monochromatic X-ray generation. Accelerator laboratory in Tsinghua University al so proposed and built Tsinghua Thomson scattering X-ray source. The hard x-ray pulse has been generated in experiment with 47 MeV electron and 20 TW laser in this year, and the parameters of the X-ray have been measured preliminarily. The experimental results are presented and discussed in this paper.

MOPPP010

Investigation of CSR Effect for Femtosecond Electron Bunches in an Isochronous Accumulator Ring

simulation, lattice, radiation, linac

589

N.Y. Huang, H. Hama, F. Hinode, S. Kashiwagi, M. Kawai, T. Muto, I. Nagasawa, K. Nanbu, Y. Shibasaki, K. Takahashi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

Coherent synchrotron radiation (CSR) from a novel isochronous ring is a candidate for light source that provides THz radiation with high average flux. A compact isochronous accumulator ring (IAR) for the maximum beam energy of 54 MeV has been designed so as to eliminate the 0th order momentum compaction factor, and the 1st order of it is mostly compensated. In addition, the path length deviation due to betatron motion is mostly compensated in a cell. Though there is no RF cavity in IAR, the injected beam may circulate for certain number of turns. Multi experimental stations can be allocated like synchrotron radiation facilities. However, it has been well known that instability due to the CSR wake field is an issue for the beam stability in the ring operated at low alpha mode. Therefore, a study for effects of the CSR wake on the bunch length and shape in IAR has been in progress. It has turned out that the maximum longitudinal field strength created by CSR would be ~ 0.15 MV/m for the case of 100 fs Gaussian bunch, which is considerably an intense field. To protect the bunch shape from the CSR wake, further study is definitely required.

MOPPP011

Narrow Band Optimization of a Compton Gamma-Ray Source Produced From an X-Band Linac

laser, simulation, emittance, linac

592

F. Albert, S.G. Anderson, C.P.J. Barty, D.J. Gibson, F.V. Hartemann, R.A. Marsh, S.S.Q. Wu
LLNL, Livermore, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Nuclear photonics is an emerging field of research that will require high precision gamma-ray (MeV) sources. In particular, nuclear resonance fluorescence applications necessitate a low (< 1%) relative gamma-ray spectral width. Within this context, Compton scattering, where laser photons are scattered off relativistic electron beams to produce tunable, collimated gamma rays, will produce the desired gamma-ray output. This paper will present the spectral narrowband optimization of such a light source currently being built at LLNL. In this case, PARMELA and elegant simulations of the full 250 MeV, high-gradient X-band linac provide the properties of the high brightness electron bunch. The electron beam simulations are then implemented into our newly developed weakly nonlinear Compton scattering code to produce theoretical gamma-ray spectra. The influence that the electron beam, laser beam and interaction geometry parameters have on the produced gamma-ray spectra will be shown with our simulations.

MOPPP013

Passive Momentum Spread Compensation by a “Wakefield Silencer”

wakefield, dipole, simulation, FEL

598

S.P. Antipov, C.-J. Jing, A. Kanareykin, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
M.G. Fedurin, K. Kusche, V. Yakimenko
BNL, Upton, Long Island, New York, USA
W. Gai, A. Zholents
ANL, Argonne, USA

Funding: DOE SBIR.
We report an observation of de-chirping of a linearly chirped (in energy) electron bunch by its passage through a 5 cm long dielectric loaded waveguide structure. The experiment was conducted at the ATF facility at BNL according to a concept dubbed a wakefield silencer originally developed at the ANL AATF*, which involves defining the electron bunch peak current distribution and selecting the optimal waveguide structure suitable for chirp cancellation using self-induced wakefields of the electron bunch. Our experiment has been carried out with a 247 micron triangular beam with a 200 keV energy spread, which was reduced by a factor of three to approximately 70 keV by passing it through a 0.95 THz dielectric-lined structure. Theoretical analysis supports the experimental results. Further exploration and applications of this technique will be discussed as well.
* M. Rosing, J. Simpson, Argonne Wakefield Accelerator Note, WF -144 (1990).

MOPPP023

Effect of DC Photoinjector Gun Voltage on Beam Dynamics in ALICE ERL

gun, booster, linac, cavity

616

Y.M. Saveliev, F. Jackson, J.K. Jones, J.W. McKenzie
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The ALICE ERL employs a DC HV photoelectron gun as an electron source. As with other machines in this class, the electron beam is not always of perfect quality. This is aggravated by that the ALICE gun has been operated so far at lower 230kV voltage compared to the design value of 350kV due to hardware limitations. The “two beams” structure was observed and experimentally investigated and found to be the result of complex processes during initial stages of beam acceleration. The experimental observations and data will be compared with those obtained at a nominal 350kV gun voltage. An investigation of the effect of the DC photogun voltage on longitudinal and transverse beam dynamics will be presented and discussed.

MOPPP028

SRF Photoinjector for Proof-of-principle Experiment of Coherent Electron Cooling at RHIC

SRF, gun, emittance, FEL

622

D. Kayran, S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, X. Liang, G.T. McIntyre, I. Pinayev, B. Sheehy, J. Skaritka, T. Srinivasan-Rao, R. Than, J.E. Tuozzolo, Q. Wu, T. Xin
BNL, Upton, Long Island, New York, USA
V. Litvinenko, M. Ruiz-Osés
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy and by Stony Brook DOE grant DE-SC0005713.
Coherent Electron Cooling (CEC) based on FEL amplifier promises to be a very good way to cool protons and ions at high energies. A proof of principle experiment to demonstrate cooling at 40 GeV/u is under construction at BNL. One of possible sources to provide sufficient quality electron beam for this experiment is a SRF photoinjector. In this paper we discuss design and simulated performance of the photoinjector based on existing 112 MHz SRF gun and newly designed single-cavity SRF linac operating at 704 MHz.

MOPPP029

Photocathodes at FLASH

cathode, photon, gun, laser

625

S. Lederer, H. Hansen, H.-H. Sahling, S. Schreiber
DESY, Hamburg, Germany
P. Michelato, L. Monaco, D. Sertore
INFN/LASA, Segrate (MI), Italy

For several years, cesium telluride photocathodes have been successfully used in the photoinjector of the Free-Electron-Laser FLASH at DESY, Germany. They show a high quantum efficiency and long lifetime and produce routinely thousands of bunches per second with a single bunch charge mostly in the range of 0.3 to 1 nC. Recent studies on lifetime, quantum efficiency, dark current, and operating experience is reported. At DESY, a new preparation system has been set-up. First cathodes have been produced and tested.

MOPPP031

A New Injection System for an Electron/Positron Linac

linac, injection, gun, positron

628

C. Liebig, M. Hüning, M. Schmitz
DESY, Hamburg, Germany

For the Linac II, which supplies the accelerator chain at DESY with electrons and positrons, a new injection system is planned. It is supposed to ensure reliable operation and to avoid the beam loss of about 60% before the positron converter and the associated activation. The main components are a 6 A/100 kV triode gun, buncher and a dispersive section for energy collimation. The output energy is 5 MeV. The new buncher structure is a hybrid of a standing wave and traveling wave structure and allows a compact design and good electron capture. Its main part is a traveling wave structure in 2π/3 mode, to which one capture cell is coupled in π mode. The function of the injector components, the entire injection system and the acceleration in the linac sections were optimized in simulations. In addition, the design is analysed in a test rig before final installation. Test rig and subsequent injector are equipped with extensive diagnostics. Besides the design of the injection system results of simulations and measurements on the test rig will be presented.

MOPPP032

Longitudinal Phase Space Studies at the PITZ Facility

laser, radiation, gun, FEL

631

M. Mahgoub, J.W. Bähr, H.-J. Grabosch, M. Groß, L. Hakobyan, G. Klemz, G. Kourkafas, M. Krasilnikov, D. Malyutin, A. Oppelt, M. Otevřel, B. Petrosyan, K. Rosbach, F. Stephan, G. Vashchenko
DESY Zeuthen, Zeuthen, Germany
I.I. Isaev
MEPhI, Moscow, Russia
Ye. Ivanisenko
IERT, Kharkov, Ukraine
M. Khojoyan
ANSL, Yerevan, Armenia
J. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China
B. Marchetti
INFN-Roma II, Roma, Italy
D. Richter
HZB, Berlin, Germany
J. Rönsch-Schulenburg
Uni HH, Hamburg, Germany

Photoinjectors are a cornerstone for short-wavelength Free Electron Lasers (FELs) like FLASH and the European XFEL in Hamburg, Germany. The Photo Injector Test facility at DESY, location Zeuthen (PITZ), was built to develop and optimize such photoinjectors. The PITZ facility is capable of generating long trains of electron bunches, which can be accelerated up to ~25 MeV/c. Studying and optimizing the longitudinal properties of the electron bunch is an important topic at PITZ. A streak system consisting of Silica Aerogel radiators, optical transition radiation (OTR) screens, optical transmission line, and a streak camera is used to study the longitudinal properties with an accuracy of some ps. Due to the high radiation level in the facility, many of the lenses in the optical transmission line have turned brown, reducing the efficiency of the system. Some of the lenses were recovered by baking them up to 180°C. In contrast, few sensitive objective lenses can not be baked, rather they were recovered via exposure to infrared radiation with the proper wave length. An overview of the system, the difficulties, and the modifications needed to overcome the radiation effects are presented.

MOPPP033

Diagnostics at PITZ 2.0 Beamline: Status and New Developments

emittance, diagnostics, dipole, FEL

634

M. Otevřel, A. Donat, H.-J. Grabosch, M. Groß, L. Hakobyan, H.M. Henschel, L. Jachmann, M. Khojoyan, G. Klemz, W. Köhler, G. Koss, G. Kourkafas, M. Krasilnikov, K. Kusoljariyakul, H. Leich, J. Li, M. Mahgoub, D. Malyutin, B. Marchetti, J. Meissner, A. Oppelt, M. Penno, B. Petrosyan, M. Pohl, S. Riemann, M. Sachwitz, B. Schöneich, J. Schultze, A. Shapovalov, F. Stephan, F. Tonisch, G. Vashchenko, L.V. Vu, T. Walter, S. Weisse, R.W. Wenndorff, M. Winde
DESY Zeuthen, Zeuthen, Germany
G. Asova
INRNE, Sofia, Bulgaria
N.I. Brusova, L.V. Kravchuk, V.V. Paramonov
RAS/INR, Moscow, Russia
A. Gonnin, M. Joré, B. Mercier, C. Prevost, A. Variola
LAL, Orsay, France
I.I. Isaev
MEPhI, Moscow, Russia
Ye. Ivanisenko
IERT, Kharkov, Ukraine
D. Richter
HZB, Berlin, Germany
S. Rimjaem
Chiang Mai University, Chiang Mai, Thailand
A.A. Zavadtsev, D.A. Zavadtsev
Nano, Moscow, Russia

The main aim of the Photo Injector Test Facility at DESY, Zeuthen (PITZ) site is to develop and test an FEL photo injector system capable of producing high charge short electron bunches of lowest possible transverse emittance to allow optimum FEL performance. The last major beamline upgrade realized in the second half of the year 2011 completed the evolution of the PITZ setup ongoing since 2005. The most recent upgrades include the installation of a new RF deflecting cavity - a prerequisite for longitudinal emittance and high resolution slice emittance measurements and installation of a new dispersive section for longitudinal phase space diagnostics of the high energy electron bunches. The paper will give an overview on electron beam diagnostics at PITZ, including the above mentioned upgrades.

MOPPP034

Simulation of the Longitudinal Phase Space Measurement with Transverse Deflecting Structure at PITZ

cavity, dipole, emittance, simulation

637

D. Malyutin, M. Krasilnikov, M. Otevřel, F. Stephan
DESY Zeuthen, Zeuthen, Germany

The main goal of the Photo Injector Test facility at DESY, Zeuthen site, (PITZ) is the development, optimization and detailed characterization of electron sources for the short wavelength Free Electron Lasers (FELs) like FLASH and the European XFEL. For successful operation of such type of FELs the injector must provide high quality electron bunches, enough short in duration with high charge and small transverse and longitudinal emittance values. Installation of the Transverse Deflecting Structure (TDS) at PITZ will provide the possibility for detailed characterization of bunch temporal profile, bunch transverse slice emittance and longitudinal phase space. The TDS cavity is currently installed at the PITZ beamline, and commissioning of the whole TDS system is expected in the spring 2012. In the first part of the paper the basic principles of the TDS deflector are described. In the next section, simulation of measurements by TDS cavity applied to the PITZ beam parameters is presented. The temporal resolution for different types of measurements is discussed. Systematic limitations are estimated.

MOPPP035

Initial Emittance and Temporal Response Measurement for GaAs Based Photocathodes

cathode, emittance, laser, cavity

640

S. Matsuba
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
Y. Honda, T. Miyajima, T. Uchiyama, M. Yamamoto
KEK, Ibaraki, Japan
X.G. Jin
Institute for Advanced Research, Nagoya, Japan
Y. Takeda
Nagoya University, Nagoya, Japan

For future light source based on Energy Recovery Linac (ERL) is planned in KEK. For the ERL, an ultra low emittance and fast temporal response and high current electron source is needed. To achieve these requirements, a high voltage DC gun with a Negative Electron Affinity photo-cathode is under development. In this development, it is important to investigate the performance of photo-cathodes. We have constructed an ERL gun test stand to measure emittance and temporal profile. We use a solenoid scan technique for emittance measurements and a deflecting cavity technique for temporal profile measurements. In this presentation, we introduce KEK ERL gun test stand and beam test results.

MOPPP036

Progress in Reducing the Back-bombardment Effect in the ITC-RF gun for t-ACTS Project at Tohoku University

cathode, gun, dipole, simulation

643

X. Li, H. Hama, F. Hinode, S. Kashiwagi, M. Kawai, T. Muto, K. Nanbu, Y. Tanaka
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
F. Miyahara
KEK, Ibaraki, Japan

An ITC (independently tunable cells) thermionic RF gun* has been developed to produce sub-picosecond electron pulses as part of the injector for coherent terahertz radiation at Tohoku University. Both experiments and simulations have shown that the back-bombardment (B.B.) effect on the LaB6 cathode is a serious issue for option. A numerical model has been developed to evaluate the temperature increase of the cathode due to B.B. in which a 2D equation for heat conduction is solved by taking the back-streaming electrons into account. Using this model we have studied the possibility of suppressing the B.B. by employing dipole field and optimization of the cathode radius, compared with experimental data. Other methods and the prospect of the RF gun will also be reported.
* H. Hama et al., New J. Phys. 8 (2006) 292

MOPPP039

Masked Photocathode for Photoinjectors

cathode, emittance, laser, vacuum

649

J. Qiang
LBNL, Berkeley, California, USA

Funding: This research was supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. This research used resources of the NERSC.
In this paper, we propose using masked photocathode in photoinjector for generating high brightness electron beam. An electrode with small hole is used as a mask to shield a large size photocathode from accelerating vacuum chamber. Using a mask will significantly increase lifetime of a photocathode by rotating unexplored photocathode material behind the electrode into the hole. Furthermore, the mask helps reduce dark current or secondary electron emission from the photocathode material. It also provides a control of initial beam transverse emittances.

MOPPP040

Resistive Wall Heating of the Undulator in High Repetition Rate FELs

undulator, wakefield, impedance, FEL

652

J. Qiang, J.N. Corlett, P. Emma
LBNL, Berkeley, California, USA
J. Wu
SLAC, Menlo Park, California, USA

Funding: Work supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
In next generation high repetition rate FELs, beam energy loss due to resistive wall wakefields will produce significant amount of heat. The heat load for a superconducting undulator (operating at low temperature), must be removed and will be expensive to remove. In this paper, we study this effect in an undulator proposed for a Next Generation Light Source (NGLS) at LBNL. We benchmark our calculations with measurements at the LCLS and carry out detailed parameter studies using beam from a start-to-end simulation. Our preliminary results suggest that the heat load in the undulator is about 2 W/m with an aperture size of 6 mm for nominal NGLS design parameters.

MOPPP041

Effect of Roughness on Emittance of Potassium Cesium Antimonide Photocathodes

emittance, cathode, laser, extraction

655

T. Vecchione, J. Feng, H.A. Padmore, W. Wan
LBNL, Berkeley, California, USA
I. Ben-Zvi, M. Ruiz-Osés, L. Xue
Stony Brook University, Stony Brook, USA
D. Dowell
SLAC, Menlo Park, California, USA
T. Rao, J. Smedley
BNL, Upton, Long Island, New York, USA

Funding: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences of the U. S. Department of Energy, under Contract DE-AC02-05CH11231, KC0407-ALSJNT-I0013, and DE-SC0005713
Here we present first measurements of the effect of roughness on the emittance of K2CsSb photocathodes under high fields. We show that for very thin cathodes the effect is negligible at up to 3 MV/m but for thicker and more efficient cathodes the effect becomes significant. We discuss ways to modify the deposition to circumvent this problem.

MOPPP042

Modeling Multi-bunch X-band Photoinjector Challenges

emittance, gun, linac, laser

658

R.A. Marsh, S.G. Anderson, C.P.J. Barty, D.J. Gibson, F.V. Hartemann
LLNL, Livermore, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
An X-band test station is being developed at LLNL to investigate accelerator optimization for future upgrades to mono-energetic gamma-ray (MEGa-Ray) technology at LLNL. The test station will consist of a 5.5 cell X-band rf photoinjector, single accelerator section, and beam diagnostics. Of critical import to the functioning of the LLNL X-band system with multiple electron bunches is the performance of the photoinjector. In depth modeling of the Mark 1 LLNL/SLAC X-band rf photoinjector performance will be presented addressing important challenges that must be addressed in order to fabricate a multi-bunch Mark 2 photoinjector. Emittance performance is evaluated under different nominal electron bunch parameters using electrostatic codes such as PARMELA. Wake potential is analyzed using electromagnetic time domain simulations using the ACE3P code T3P. Beam-loading effects and low level rf compensation schemes are explored as well, using a semi-analytic formalism and computer algorithm. Plans for multi-bunch experiments and implementation of photoinjector advances for the Mark 2 design will also be discussed.

MOPPP046

RF Gun Photocathode Research at SLAC

gun, cathode, laser, emittance

664

E.N. Jongewaard, R. Akre, A. Brachmann, W.J. Corbett, S. Gilevich, K. Grouev, P. Hering, P. Krejcik, J.R. Lewandowski, H. Loos, T. M. Montagne, J. Sheppard, P. Stefan, A.E. Vlieks, S.P. Weathersby, F. Zhou
SLAC, Menlo Park, California, USA

Funding: DOE contract DE-AC02-76SF00515.
LCLS is presently operating with a third copper photocathode in the original rf gun, with a quantum efficiency (QE) of ~1x10^-4 and projected emittance eNx,y=0.45 μm at 250 pC bunch charge. The spare LCLS gun is installed in the SLAC Accelerator Structure Test Area (ASTA), processed to the design rf gradient of >120 MV/m. As part of a wider photocathode R&D program, a UV laser system and additional gun diagnostics are being installed at ASTA to measure QE, QE lifetime, and electron beam emittance under a variety of operating conditions. The near-term goals are to test and verify the spare photocathode production/installation sequence, including transfer from the final holding chamber to the rf gun. Mid- and longer-term goals include development of a rigorous understanding of plasma and laser-assisted surface conditioning and investigation of new, high-QE photocathode materials. In parallel, an x-ray photoemission spectroscopy station is nearing completion, to analyze Cu photocathode surface chemistry. In this paper we review the status and anticipated operating parameters of ASTA and the spectroscopy test chamber.

MOPPP047

Characterization of the First SRF Electron Beam Source at the Naval Postgraduate School

cavity, cathode, SRF, coupling

667

A.D. Holmes, A.B. Baxter, C.W. Bennett, J.R. Harris, J.W. Lewellen, R. Swent
NPS, Monterey, California, USA
J.M. Didoszak, J.M. Utschig
ONR, Arlington, Virginia, USA

In June 2011, the Naval Postgraduate school (NPS) received the 500 MHz Mark I quarter-wave superconducting RF (SRF) electron beam source and, among other firsts, completed the first cool down and characterization of an SRF beam source at a US Naval facility. The Mark I has a photocathode with adjustable position and uses a unique cascaded RF coupler design. As part of an on-going advanced electron source development project, the NPS Beam Physics Laboratory (BPL) team continues characterization of the Mark I cavity at various cathode stalk, coupler, and probe positions. Methods and experimentation used to measure the cavity Q and β, as well as characteristic results, with respect to coupler, cathode stalk, and probe positions are presented.

MOPPP050

Physics Results of the NSLS-II Linac Front End Test Stand

linac, emittance, simulation, gun

673

R.P. Fliller, F. Gao, J. Rose, T.V. Shaftan, X. Yang
BNL, Upton, Long Island, New York, USA
G. Blokesch
PPT, Dortmund, Germany
C. Piel
RI Research Instruments GmbH, Bergisch Gladbach, Germany

Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The NSLS-II linac is produced by Research Instruments and will be commissioned in the spring of 2012. As part of the procurement, the linac front end consisting of the gun, prebunching cavity, and diagnostics was delivered early to BNL for testing. We designed a short beamline to supplement the Front End diagnostics to characterize the beam. These tests were instrumental in demonstrating the functioning of the gun, pinpointing technical problems at an early project stage and gaining experience with the linac gun by BNL staff prior to commissioning of the full linac. In this report we show the results of the tests, including charge, bunch length, and transverse emittance measurements and compare them with the relevant linac specifications.

MOPPP056

Injection Transient Motion at PLS-II

kicker, injection, septum, linac

688

I. Hwang, T. Ha, Y.D. Joo, C. Kim, M. Kim, S.H. Kim, B.-J. Lee, E.H. Lee, S. Shin
PAL, Pohang, Kyungbuk, Republic of Korea

PLS-II is an upgraded third generation synchrotron which includes many insertion devices with improved beam properties. Top-up operation is short time-interval injection to make roughly constant current and is essential to provide high intensity beam. When the electrons are injected to synchrotron, the stored beam is disturbed by small error of the injection system and the beam quality at the beamline can be decreased. We present this injection transient motion at PLS-II.

MOPPP065

Effects of Geometrical Errors on the Field Quality in a Planar Superconducting Undulator

undulator, simulation, photon, status

708

J. Bahrdt
HZB, Berlin, Germany
J. Bahrdt, Y. Ivanyushenkov
ANL, Argonne, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Short-period superconducting undulators are being developed at the Advanced Photon Source (APS). The first test device is being fabricated. It is using a relatively short magnetic structure that will be replaced with a longer magnet in the second device. High quality magnetic field with the phase errors at a level of 2 degrees rms were achieved in the prototype magnets due to very accurate winding of the superconducting coils on the formers machined to about 10-μm precision. Manufacturing meters-long undulator structures to such tolerances would be very difficult or even impossible. It is therefore important to understand the effects of the mechanical tolerances in the coil manufacture process on the quality of the magnetic field. The effects of geometrical errors in the position of a superconducting winding in a planar structure are simulated with the RADIA software package. A field profile of a long non-ideal undulator magnet is then built and analyzed in terms of the first and second field integrals as well as phase errors. The results of the systematic study of the geometrical errors on the field quality are presented in this paper.

MOPPP068

Beam Heat Load and Pressure in the Superconducting Undulator Installed at ANKA

undulator, vacuum, storage-ring, simulation

717

S. Casalbuoni, S. Gerstl, A.W. Grau, T. Holubek, D. Saez de Jauregui
Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany

A superconducting undulator has been installed in the ANKA (ANgstrom source KArlsruhe) storage ring since March 2005. The beam heat load and pressure on the cold bore were analyzed in the first two years of operation, during which the undulator was operated mainly with open gap. We report here on a larger statistic of beam heat load and pressure data collected in the last years with the undulator operated at different gap positions. The effects of vacuum leaks in the storage ring on the superconducting undulator operation are also described.

MOPPP069

First Measurements of COLDDIAG: A Cold Vacuum Chamber for Diagnostics

solenoid, diagnostics, vacuum, insertion

720

S. Gerstl, T. Baumbach, S. Casalbuoni, A.W. Grau, M. Hagelstein, T. Holubek, D. Saez de Jauregui
Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
R. Bartolini, M.P. Cox, J.C. Schouten, R.P. Walker
Diamond, Oxfordshire, United Kingdom
M. Migliorati, B. Spataro
INFN/LNF, Frascati (Roma), Italy
I.R.R. Shinton
UMAN, Manchester, United Kingdom

Superconductive insertion devices can reach, for the same gap and period length, higher fields with respect to permanent magnet insertion devices. One of the still open issues for the development of superconductive insertion devices, is the understanding of the heat intake from the electron beam. COLDDIAG, a cold vacuum chamber for diagnostics was designed and built specifically for this purpose. With the equipped instrumentation, which covers temperature sensors, pressure gauges, mass spectrometers as well as retarding field analyzers it is possible to measure the beam heat load, total pressure, gas content as well as the flux of particles hitting the chamber walls. Here we report about the preliminary measurements and results of COLDDIAG installed in the Diamond storage ring.

MOPPP072

Performance of APPLE-II Type Quasi-Periodic Undulator at HiSOR

undulator, radiation, polarization, photon

729

S. Sasaki, M. Arita, K. Goto, A. Miyamoto, T. Okuda
HSRC, Higashi-Hiroshima, Japan

A 1.8-m-long 78-mm-period quasi-periodic APLPE-II undulator was installed in the 700-MeV HiSOR storage ring of Hiroshima Synchrotron Radiation Center. At 23-mm nominal minimum gap, the fundamental photon energies are 3.1 eV, 6.5 eV, and 4.8 eV for horizontal linear, vertical linear, and circular polarization, respectively. The photon energies of observed fundamental and higher harmonic radiations are in good agreement with those of model calculations using measured undulator field and the HiSOR beam parameters. Also, observed flux thorough a slit and a grating monochromator was more than twice larger than that from previously installed 100-mm-period helical undulator for the whole range of radiation spectra. The feedforward COD correction was done to avoid the intensity fluctuation of photon beam in other BM beamlines due to the gap and phase motion of undulator. No fatal effect on the stored electron beam by installing the undulator was observed though a slight beam size change was observed at the minimum gap.

MOPPP074

Magnetic Field Measurement for a THz Undulator Using the Vibrating Wire Method

undulator, radiation, laser, resonance

732

S. Kashiwagi, H. Hama, F. Hinode, M. Kawai, X. Li, T. Muto, K. Nanbu, Y. Tanaka
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

Funding: This work is supported by the Ministry of Education, Science, Sports and Culture, Grant-in-Aid for Scientific Research (S), Contract #20226003.
We constructed the undulator that is a basically a Halbach planer type for a generation of intense coherent terahertz radiation from the very short electron bunch. The period length of the undulator and the number of periods are 100 mm and 25, respectively. Its maximum magnetic field is 0.41 T and the K-value is 3.82 with 54 mm gap. The vibrating wire method is studied to measure the periodic magnetic field of the undulator. By measuring amplitudes and phases of standing waves excited on the wire by the Lorentz force between AC current and magnetic field, we can reconstruct the magnetic field distribution along the wire. The theoretical analysis has been performed for the THz undulator and derived a relation between a reproducibility of undulator field and the number of the harmonic mode to use for the reconstruction. A model experiment was demonstrated using 20cm wire and one pair of permanent magnet block. The theoretical study and the results of model experiment using the vibrating wire method will be shown in this conference.

MOPPP076

Design Considerations for a Hybrid Undulator Applied in a Terahertz FEL Oscillator

undulator, FEL, radiation, cavity

738

B. Qin, M. Fan, Y.Q. Xiong
Huazhong University of Science and Technology (HUST), Wuhan, People's Republic of China
Y.J. Pei
USTC/NSRL, Hefei, Anhui, People's Republic of China
P. Tan
HUST, Wuhan, People's Republic of China

A planer undulator using hybrid permanent magnet scheme was designed for a FEL based 1THz~3THz radiation source. The influence of the undulator magnetic field errors, including peak field shift and field integrals errors, on the coherent radiation performance such as the gain per pass is investigated. And finally specifications of the undulator are determined.

MOPPP085

Single Electron Dynamic of Microwave Undulator

undulator, FEL, radiation, free-electron-laser

753

C. Chang, J. Neilson, C. Pellegrini, M. Shumail, S.G. Tantawi
SLAC, Menlo Park, California, USA

The analytical and numerical calculations for the dynamic of single electron and beam in RF undulator have been conducted and compared. The transverse and longitudinal velocity, trajectory, energy variation, and the spontaneous radiation are studied. It is found that the forward and backward wave (FW/BW) components have different contribution on electron motion and radiation, most of the energy spread comes from FW component, in other words, the effect of FW on modulating the electron energy is much stronger than that of BW for the same undulating-amplitude value, which mechanism has been analyzed.

MOPPP088

Control of Nonlinear Dynamics by Active and Passive Methods for the NSLS-II Insertion Devices

undulator, polarization, insertion, insertion-device

759

J. Bengtsson, O.V. Chubar, C.A. Kitegi, T. Tanabe
BNL, Upton, Long Island, New York, USA

Funding: US DOE, Contract No. DE-AC02-98CH10886.
Nonlinear dynamics effects from insertion devices (IDs) are known to affect the electron beam quality of third generation synchrotron light sources. In particular, beam lifetime, dynamical aperture and injection efficiency. Methods to model the IDs' non-linear effects are known, e.g. by second-order (in the inverse electron energy) kick maps. Methods to compensate these effects are known as well, e.g. by first-order thin or thick magnetic kicks introduced by "magic fingers," "L-shims," or "current strips." However, due to physical or technological constraints, these corrections are typically only partial. Therefore, a precise model is required for a correct minimization of the residual nonlinear dynamics effects for the combined magnetic fields of the ID and compensating magnets. We outline a systematic approach for such predictions, based on 3D magnetic field and local trajectory calculation in the ID by the Radia code, and particle tracking by Tracy-3. The optimal geometry for the compensating magnets is determined from these simulations using a combination of linear algebra and genetic optimization.

MOPPP090

Spectral Performance of Segmented Adaptive-Gap In-Vacuum Undulators for Storage Rings

undulator, vacuum, photon, radiation

765

O.V. Chubar, J. Bengtsson, A. Blednykh, C.A. Kitegi, G. Rakowsky, T. Tanabe
BNL, Upton, Long Island, New York, USA
J.A. Clarke
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: US DOE, Contract No. DE-AC02-98CH10886.
We propose an approach to the optimization of segmented in-vacuum undulators, in which different segments along an undulator may have different gaps and periods. This enables close matching between the gaps and the vertical "envelope" of electron beam motion in a storage ring straight section (carefully satisfying the associated vertical "stay clear" constraint) and, at the same time, precise tuning of all the segments to the same fundamental photon energy. Thanks to this, the vertical gaps in segments located closer to straight section center can be smaller than at extremities, and so the entire undulator structure can offer better magnetic performance, compared to the case of a standard undulator with constant gap (and period) over its length. We will present magnetic field, radiation flux, brightness and intensity calculation results for such segmented adaptive-gap in-vacuum undulators and demonstrate their gain in spectral performance over standard in-vacuum undulators, both for room-temperature and cryo-cooled realizations.

MOPPP091

Recent Developments at the DELTA THz Beamline

laser, radiation, storage-ring, undulator

768

P. Ungelenk, M. Bakr, H. Huck, M. Höner, S. Khan, R. Molo, A. Nowaczyk, A. Schick, M. Zeinalzadeh
DELTA, Dortmund, Germany

Funding: Work supported by DFG, BMBF, and by the Federal State NRW.
During 2011, a new dedicated THz beamline has been constructed and commissioned at DELTA, a 1.5 GeV synchrotron light source operated by the TU Dortmund University. This beamline enables extracting and detecting coherent THz pulses caused by a laser-induced density modulation of the electron bunches. Ongoing experiments aim at characterizing the THz radiation as well as investigating the evolution of the density modulation over subsequent revolutions following the initial laser-electron interaction in an undulator.

MOPPR001

Resonant Spin Depolarisation Measurements at the SPEAR3 Electron Storage Ring

storage-ring, lattice, polarization, synchrotron

771

K.P. Wootton, R.P. Rassool
The University of Melbourne, Melbourne, Australia
M.J. Boland, Y.E. Tan
ASCo, Clayton, Victoria, Australia
W.J. Corbett, M.H. Donald, X. Huang, R.R. Ortiz, J.A. Safranek, K. Tian
SLAC, Menlo Park, California, USA

Accurate electron beam energy measurements are valuable for precision lattice modelling of high-brightness light sources. At SPEAR3 the beam energy was measured using the resonant spin depolarisation method with striplines to resonantly excite the spin tune and a sensitive NaI scintillator beam loss monitor was used to detect resulting changes in Touschek lifetime. Using the combined apparatus an electron beam energy of 2.997251(7) GeV was measured, giving a relative uncertainty better than 3x10^-6. The measured momentum compaction factor was found to be in close agreement with the numerical model value using rectangular defocussing gradient dipoles with measured magnetic field map profiles. In this paper we outline the chosen experimental technique, with emphasis on its applicability to electron storage rings in general.

MOPPR003

Beam Diagnostic Systems for the TRIUMF e-linac

linac, TRIUMF, diagnostics, EPICS

777

J.M. Abernathy, D. Karlen, M.O. Pfleger, P.R. Poffenberger, D.W. Storey
Victoria University, Victoria, B.C., Canada
F. Ames, P.S. Birney, D.P. Cameron, J.V. Holek, S.Y. Kajioka, S. Kellogg, M. Lenckowski, M. Minato, W.R. Rawnsley, J.E. Richards, V.A. Verzilov
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

Funding: NSERC, CFI, BCKDF.
The TRIUMF electron linac will include a suite of diagnostics systems, including current, beam position, and beam profile monitors. This talk will present an overview of the diagnostic systems and give details about the view screen system, having both scintillator and OTR foils. Results from tests with the prototype low energy beam transport system will be shown. Diagnostic systems are particularly challenging for the e-linac due to the 500 kW beam power envisaged, with beam currents up to 10 mA at 50 MeV.

MOPPR007

Investigation of Techniques for Precise Compton Polarimetry at ELSA

polarization, photon, laser, simulation

783

R. Zimmermann, W. Hillert
ELSA, Bonn, Germany

Funding: Work supported by DFG within SFB/TR16
A Compton polarimeter is currently being installed at the Electron Stretcher Facility ELSA to monitor the degree of polarization of the stored electron beam. For this purpose, circularly polarized light that is emitted by a laser and backscattered off the beam has to be detected. When the polarization of the laser light is switched from left-hand to right-hand circular polarization, the spatial distribution of the backscattered photons is shifted. The extent of this modification is a measure of the beam's polarization degree. Two different experimental techniques that are suitable for a measurement of the effect were compared and evaluated closer through numerical simulations that will be presented in this contribution.

MOPPR008

The Beam Loss Monitoring System at ELSA

injection, extraction, booster, monitoring

786

D. Proft, A. Balling, F. Frommberger, W. Hillert
ELSA, Bonn, Germany

A new diagnostic tool to monitor beam loss in the storage ring at the Electron Stretcher Facility ELSA has been set up. It enables the investigation of causes for electron loss in real time, providing an essential tool needed to achieve the planned beam current upgrade from 30 mA to 200 mA. The monitoring system consists of 32 pin-diode based radiation detectors spread around the storage ring. Therefore, individual electron loss can be localized after each quadrupole. The readout system was designed to allow an integration of single loss events within 70 μs in order to be able to correlate these events to machine state changes. The used monitoring hardware and readout system will be detailed. Furthermore first measurements of the beam loss during injection, the fast energy ramp during acceleration and the extraction phase will be presented.

MOPPR009

Dynamic Closed Orbit Correction During the Fast Energy Ramp of ELSA

closed-orbit, polarization, acceleration, controls

789

J.-P. Thiry, A. Balling, A. Dieckmann, F. Frommberger, W. Hillert
ELSA, Bonn, Germany

ELSA is a fast ramping stretcher ring supplying polarized electrons to hadron physics experiments. To preserve the degreee of polarization, it is necessary to continuously correct the vertical orbit when accelerating the beam from 1.2 GeV to 2.4 GeV. Acceleration is performed within 300 ms, thus with a ramping speed of 4 GeV/s. During the acceleration, beam positions are measured at a rate of 1 kHz using 32 beam position monitors, which are mounted close to the quadrupole magnets. The demanding task is to achieve a vertical rms deviation not exceeding 50 μm all along the fast energy ramp. Therefore, dynamic orbit corrections are applied by means of offline feed-forward techniques, driving 32 vertical steerer magnets which can change currents in less than 10 ms. In our contribution, we show the used concepts and the implementation of the precise closed orbit correction system at ELSA.

MOPPR011

A New Diagnostic Beamline at ELSA

synchrotron, radiation, synchrotron-radiation, diagnostics

795

S. Zander, F. Frommberger, P. Hänisch, W. Hillert, B. Neff
ELSA, Bonn, Germany

Funding: Funded by the DFG within the SFB / TR 16.
At the Electron Stretcher Facility (ELSA), a new synchrotron light diagnostic Beamline has been installed in order to perform high resolution, transversal and longitudinal beam profile measurements by analyzing the emitted synchrotron light. For this purpose, the main deflecting AL mirror selects a wide range of wavelengths from 200–800 nm out of the whole synchrotron spectrum. The setup of the beamline and its relevant components will be presented.

MOPPR012

Beam Induced Fluorescence Monitors for FAIR

vacuum, ion, target, antiproton

798

F. Becker, C.A. Andre, C. Dorn, P. Forck, R. Haseitl, B. Walasek-Höhne
GSI, Darmstadt, Germany
T. Dandl, T. Heindl, A. Ulrich
TUM/Physik, Garching bei München, Germany

Online profile diagnostic is preferred to monitor intense hadron beams at the Facility of Antiproton and Ion Research (FAIR). One instrument for beam profile measurement is the gas based Beam Induced Fluorescence (BIF)-monitor. It relies on the optical fluorescence of residual gas, excited by beam particles. Depending on the beam parameters and vacuum constraints, BIF monitors can be operated at base pressure or in dedicated local pressure bumps. Spectroscopic data in nitrogen and rare gases confirms an exploitable dynamic range from UHV to atmospheric pressure. Optical transitions and corresponding beam profiles are discussed for gas pressures from 10^-3 to 30 mbar. Fundamental limitations for some application scenarios will be addressed as well.

MOPPR014

Installation and Test of a Beam Loss Monitor System for the S-DALINAC

controls, monitoring, background, radiation

804

R. Stegmann, U. Bonnes, C. Burandt, R. Eichhorn, F. Hug, L.E. Jürgensen, N. Pietralla
TU Darmstadt, Darmstadt, Germany
D. Proft
ELSA, Bonn, Germany

Funding: This work is supported by the DFG through SFB 634.
The superconducting Darmstadt linear accelarator S-DALINAC is designed for accelerating electrons up to energies of 130 MeV for measurements in nuclear physics at small momentum transfers. For the purpose of machine protection and in order to increase reliability and efficiency an efficient tool for on-line measurements of beam losses down to electron energies of 1 MeV is desirable. Therefore a system of beam-loss monitors has been developed, installed, and tested. The system consists of commercially availiable PIN-diods and newly developed electronics. Implementation in the S-DALINAC's control system is done via EPICS IOC. We will report on the setup of the beam-loss monitoring system and on its initial performance in first tests.

MOPPR015

Bunch-by-bunch Feedback Systems at the DELTA Storage Ring

feedback, kicker, synchrotron, injection

807

M. Höner, M. Bakr, H. Huck, S. Khan, R. Molo, A. Nowaczyk, A. Schick, P. Ungelenk, M. Zeinalzadeh
DELTA, Dortmund, Germany

Funding: Work supported by BMBF (05K10PEB)
At the DELTA 1.5-GeV electron storage ring operated as a synchrotron radiation source by the TU Dortmund University, bunch-by-bunch feedback systems have been recently installed and commissioned to detect and suppress longitudinal as well as transverse multibunch instabilities. Besides that, the feedback systems are used as a diagnostics tool. Growth rates of multibunch instabilities and their dependence on the beam current have been measured. Additionally, the oscillation amplitudes of electron bunches have been studied during the injection process.

MOPPR016

Femtosecond Level Electron Bunch Diagnostic at Quasi – CW SRF Accelerators: Test Facility ELBE

diagnostics, SRF, laser, photon

810

M. Gensch, C. Kaya, U. Lehnert, P. Michel, Ch. Schneider, W. Seidel
HZDR, Dresden, Germany
G. Geloni
European XFEL GmbH, Hamburg, Germany
M. Helm
FZD, Dresden, Germany
H. Schlarb, A. Shemmary, N. Stojanovic
DESY, Hamburg, Germany

Funding: BMBF through the PIDID proposal and HGF through the ARD initiative
At the srf based prototype cw accelerator ELBE a new electron beamline, providing for femtosecond electron bunches with nC bunch charges and repetition rates in the 1 – 200 KHz regime and with pC bunch charge and repetition rates of 13 MHz is currently constructed. The 40 MeV electrons will be used in photon-electron interaction experiments with TW and PW class laser and the generation of broad band and narrow bandwidth coherent THz pulses. In this paper we outline ideas for novel online diagnostics of the electron bunch properties (e.g. arrival time and bunch form) based on the time and frequency domain analysis of the emitted coherent THz radiation but also based on direct measurements by e.g. electro-optic sampling. The suitability of ELBE as a testbed for diagnostic of future cw X-ray photon sources (e.g. energy recovery linacs) will be discussed.

MOPPR017

Preliminary Measurement Results of the Upgraded Energy BPM at FLASH

pick-up, LLRF, controls, FEL

813

U. Mavrič, M. Felber, C. Gerth, H. Schlarb
DESY, Hamburg, Germany
W. Jałmużna, A. Piotrowski
TUL-DMCS, Łódź, Poland

The energy beam position monitor in the dispersive section of the two bunch compressors is a valuable instrument for regular operation of FLASH. Recently, an upgrade of the existing instrument to a uTCA form factor has been started. The basic principle of the time-of-flight measurement will remain the same, however the detection of the phases and amplitudes of two pulses has been moved to the programmable gate array. Other changes include different RF frequencies of detection, optimization of the front-end section and integration into the control system. A preliminary version of the system has been tested at FLASH and the results are presented in the paper.

MOPPR018

Beam Halo Monitor for FLASH and the European XFEL

diagnostics, free-electron-laser, laser, pick-up

816

A. Ignatenko, N. Baboi, O. Hensler, M. Schmitz, K. Wittenburg
DESY, Hamburg, Germany
H.M. Henschel, W. Lange, W. Lohmann
DESY Zeuthen, Zeuthen, Germany
A. Ignatenko
BTU, Cottbus, Germany
S. Schuwalow
Uni HH, Hamburg, Germany

The Beam Halo Monitor for Free-electron Laser in Hamburg (FLASH) based on pCVD diamond and monocrystalline artificial sapphire sensors has been successfully commissioned in September 2009. It is a part of the beam dump diagnostics and ensures safe beam dumping. Its description and the experience gained during its operation are given. The ideas on the design and aspects of operation of the similar systems at FLASH II and the European XFEL are presented.

MOPPR019

Beam Profile Imaging Based on Backward Transition Radiation in the Extreme Ultraviolet Region

radiation, target, FEL, diagnostics

819

L.G. Sukhikh, S. Bajt, G. Kube
DESY, Hamburg, Germany
W. Lauth
IKP, Mainz, Germany
Yu.A. Popov, A. Potylitsyn
Tomsk Polytechnic University, Tomsk, Russia

Backward transition radiation (BTR) in the optical spectral region is widely used for beam profile diagnostics in modern electron linacs. However, the experience from linac based light sources shows that BTR diagnostics might fail because of coherence effects in the emission process. To overcome this problem of coherent emission it was proposed to use BTR in the extreme ultraviolet (EUV) region*, and measurements of the angular EUV BTR distribution were presented in Ref. **. This contribution summarizes the results of a beam profile imaging experiment using EUV BTR. The experiment was carried out using the 855 MeV electron beam of the Mainz Microtron MAMI. EUV BTR was generated at a molybdenum target deposited onto a silicon substrate, and imaging was realized using a spherical multilayer mirror which was optimized for a wavelength of 19 nm. Preliminary results will be presented and compared to ordinary optical BTR imaging together with a discussion of future possibilities of the proposed diagnostic method.
* L.G. Sukhikh et al., Nucl. Instrum. Methods A623, 567 (2010).
** L.G. Sukhikh et al., Proc. of DIPAC-2011, Hamburg (Germany), 544 (2011).

MOPPR024

Non-intercepting Emittance Measurements by means of Optical Diffraction Radiation Interference for High Brightness Electron Beam

radiation, quadrupole, emittance, target

831

A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
V. Balandin, N. Golubeva, K. Honkavaara, G. Kube
DESY, Hamburg, Germany
M. Castellano, E. Chiadroni
INFN/LNF, Frascati (Roma), Italy
L. Catani
INFN-Roma II, Roma, Italy

Conventional intercepting transverse electron beam diagnostics, e.g. based on Optical Transition Radiation (OTR), cannot tolerate high power beams without remarkable mechanical damages of the diagnostics device. Optical Diffraction Radiation (ODR) is an excellent candidate for the measurements of the transverse phase space parameters in a non-intercepting way. One of the main limitations of this method is the low signal to noise ratio, mainly due to the unavoidable synchrotron radiation background. This problem can be overcome by using ODRI (Optical Diffraction Radiation Interference). In this case the beam goes through two slits opened on metallic foils, placed in a distance shorter than the radiation formation zone. Thanks to the shielding effect of the first screen a nearly background-free ODR interference pattern can be measured allowing the determination of the beam size and the angular divergence. Here we report the first measurements, carried out at FLASH (DESY, Germany), of the beam emittance using ODRI. Our results demonstrate the unique potential of this technique.

MOPPR025

The BPM DAQ System Upgrade for SuperKEKB Injector Linac

linac, emittance, positron, injection

834

M. Satoh, K. Furukawa, F. Miyahara, T. Suwada
KEK, Ibaraki, Japan
T. Kudou, S. Kusano
MELCO SC, Tsukuba, Japan

The non-destructive beam position monitor (BPM) is indispensable diagnostic tool for the stable beam operation. In the KEK Linac, approximately nineteen BPMs with the strip-line type electrodes are used for the beam orbit measurement and feedback. In addition, some of them are also used for the beam energy feedback loops. The current DAQ system consists of the fast digital oscilloscopes. A signal from each electrode is analyzed with a predetermined response function up to 50 Hz. The beam position resolution of current system is limited to about 0.5 mm because of ADC resolution. Towards SuperKEKB project, we have a plan to upgrade the BPM DAQ system since the Linac should provide the smaller emittance beam. We will report the system description of the new DAQ system and the results of performance test in detail.

MOPPR029

Upgrade of Ionization Profile Monitor (IPM) in the J-PARC 3-GeV RCS

ion, vacuum, status, space-charge

840

H. Harada, K. Yamamoto, M. Yoshimoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

Ionization Profile Monitors (IPM) were installed and operated in the J-PARC 3-GeV RCS for the observation of circulating beam profile. In IPM system, ions produced by the beam passing through beam chamber lead to Multi Channel Plate (MCP) by electric field, and the signals from the MCP are observed as the beam profile. The IPM system has an upgrade plan for the optimization of the electric fields. This will be reported the upgrade status of the IPM.

MOPPR032

Electron Beam Diagnostics based on Transverse Feedback System at Duke Storage Ring

storage-ring, feedback, monitoring, FEL

849

W. Xu, D.H. He
USTC/NSRL, Hefei, Anhui, People's Republic of China
J.Y. Li, W. Wu, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
To combat electron beam instabilities, a field programmable gate array (FPGA) based bunch-by-bunch transverse feedback (TFB) has been developed for the Duke storage ring. While it is capable of suppressing transverse beam instabilities for multi-bunch operation, the TFB system has not been needed for typical operation of the Duke storage ring FEL. To explore the great potential of this system, we have focused on the development of TFB based beam diagnostics. A TFB based tune measurement system has been developed using two methods: the tune scan method and tune monitoring method. With the tune monitoring method, a much faster method of the two, we have studied the tune stability of the electron beam in the Duke storage ring. This tune measurement system also allows us to conduct chromaticity measurements more quickly, compared with the existing chromaticity measurement system using a network analyzer. Finally, the TFB based tune system has been used to calibrate the tune knob and chromaticity knob for the Duke storage ring.

MOPPR034

A Laser Wire System at Electron Beam Transport Line in BEPCII

laser, photon, positron, simulation

852

C. Zhang, J. Cao, Q.Y. Deng, Y.F. Sui
IHEP, People's Republic of China

Funding: National Natural Science Foundation of China
A Laser Wire system is under development at transport line in BEPCII (Beijing Electron Positron Collider). The structure of whole system is briefly described in this paper. Some work on laser and detector are presented. We also discussed the challenge of Laser Wire and some other things that can affect measurement. According to the plan, the Laser Wire will be installed in electron beam transport line in the summer of 2012.

MOPPR035

Study of the Signal Processing System for a Cavity Beam Position MonitorS

cavity, FEL, factory, simulation

855

B.P. Wang, Y.B. Leng, L.Y. Yu, W.M. Zhou
SINAP, Shanghai, People's Republic of China
Z.C. Chen, R.X. Yuan, N. Zhang
SSRF, Shanghai, People's Republic of China

A cavity beam position monitor (CBPM), which can realize nanometer-level resolution as reported, is important and indispensable for a free electron laser (FEL) facility. A prototype of CBPM, with resonant frequency of 5712 MHz, has been installed in the Shanghai deep ultraviolet free-electron laser source (SDUV-FEL) facility. A plug & play CBPM signal processor based on a broadband oscilloscope embedded IOC and FFT technology has been developed to do quick evaluation of prototype. According to the evaluation results, a series of simulation using Monte Carlo simulation method, has been carried as a guideline for the design of dedicated CBPM signal processing system. The development progress of signal processing system will be introduced as well.

MOPPR040

Design and Measurements of a Test Stand for the SEM-Grid System of the ESS-BILBAO

vacuum, diagnostics, emittance, linac

867

D. Belver, J. Feuchtwanger, P.J. González
ESS Bilbao, LEIOA, Spain
F.J. Bermejo
Bilbao, Faculty of Science and Technology, Bilbao, Spain
V. Etxebarria, J. Jugo
University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain

In the framework of the ESS-Bilbao accelerator, a test stand for the development of Secondary Electron EMission grid (SEM-Grid) has been designed and manufactured as a part of the diagnostics system for beam profile measurements. This test stand is a vacuum system based on an EQ 22/35 electron source from SPECS used as a beam injector. This electron source has an energy range from 0 to 5 KeV and a maximum beam current up to 200 μA. Although we have thought in a SEM-Grid of 40 wires (20 wires in each X and Y direction), two prototypes of 16 wires (8x8) of 250 μm diameter and spaced 1 and 2 mm, respectively, have been developed due to its easier implementation and tested in the test stand. In order to develop an electronics readout system for the SEM-Grid, first studies of the prototype signals have been done. The secondary emission current of each wire will be integrated and amplified to provide a significant voltage signal that can be measured by our acquisition system. A description of the SEM-Grid test stand and the measurements developed is given here.

MOPPR047

Study of the Response of Low Pressure Ionisation Chambers

proton, target, monitoring, synchrotron

888

E. Nebot Del Busto, B. Dehning, E. Effinger, V. Grishin, J.F. Herranz Alvarez
CERN, Geneva, Switzerland

The Beam Loss Monitoring System (BLM) of the Large Hadron Collider (LHC) is based on parallel plate Ionization Chambers (IC) with active volume ~1.5l and a nitrogen filling gas at 0.1 bar overpressure. At the largest loss locations, the ICs generate signals large enough to saturate the read-out electronics. A reduction of the active volume and filling pressure in the ICs would decrease the amount of charge collected in the electrodes, and so provide a higher saturation limit using the same electroncis. This makes Little Ionization Chambers (LIC) filled with both reduced pressure and active volume a good candidate for these high radiation areas. In this contribution we present measurements performed with several LIC monitors with reduced active volume and various filling pressures. These detectors were tested under various conditions with different beam setups, with standard LHC ICs used for calibration purposes.

MOPPR059

Modeling Space-charge and its Influence on the Measurement of Phase Space in ALICE by Tomographic Methods

space-charge, quadrupole, injection, diagnostics

918

M.G. Ibison, D.J. Holder
The University of Liverpool, Liverpool, United Kingdom
K.M. Hock, B.D. Muratori, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: STFC.
ALICE is an experimental electron accelerator designed to operate over a range of energies up to 35 MeV, and with up to 80 pC bunch charge. A dedicated tomography diagnostic section allows measurement of the transverse phase space with different beam parameters. In the low-energy, high-charge regime, space charge effects must be considered: to quantify these effects, the tracking code GPT has been used to simulate beams in the tomography diagnostic section. The results can be compared with simplified models, and with experimental measurements.

MOPPR067

Simulations of Fast X-ray Detectors Based on Multichannel Plates

photon, simulation, scattering, cathode

939

Z. Insepov, B.W. Adams, J. Norem
ANL, Argonne, USA
V. Ivanov
Muons, Inc, Batavia, USA

Funding: Argonne National Laboratory
High-performance detectors with high spatial and time resolutions are required for imaging of fast processes, time-resolved coherent scattering, and time-resolved x-ray spectroscopy. Recent developments in micro-channel plate (MCP) technology are important for sub-ns and 2d-spatially resolving x-ray detection. A Monte Carlo code was used to calculate the yields of secondary electrons emitted from a photo-cathode irradiated by X-rays, E=1-10 keV. Several photo-cathode materials were tested, including Al2O3, MgO, carbon, copper, WO3. The calculated emissive characteristics were used as input parameters of a second Monte Carlo code that was capable of calculating the gain/time characteristics of the MCP based X-Ray detector. A new type of X-Ray detector based on MCPs coated by resistive and emissive layers inside the pores by using atomic-layer deposition (ALD) promises a large parameter space where optimizations can take place. These optimizations for x-ray-specific applications are expected to improve the spatial resolution to 100 microns and the time resolution to 50 ps, and the development of high-quantum-yield photo-cathodes based on MCPs with grazing incidence inside the pores.

MOPPR070

Beam Profile Measurement in MTA Beam Line for High Pressure RF Cavity Beam Test

cavity, proton, diagnostics, linac

948

M.R. Jana, A.D. Bross, S. Geer, C. Johnstone, T. Kobilarcik, G.M. Koizumi, M.A. Leonova, A. Moretti, M. Popovic, T.A. Schwarz, A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, USA
M. Chung
Handong Global University, Pohang, Republic of Korea
M.G. Collura
Politecnico di Torino, Torino, Italy
B.T. Freemire, P.M. Hanlet, Y. Torun
IIT, Chicago, Illinois, USA

Funding: This work is supported by the United States Department of Energy under contract DE-AC02-07CH11359.
The recent High Pressure RF (HPRF) cavity experiment at the MuCool Test Area (MTA) used a 400 MeV Linac proton beam to study the beam loading effect. When the energetic proton beam passes through the cavity, it ionizes the inside gas and produces electrons. These electrons consume RF power inside the cavity. The number of electrons produced per cm inside the cavity (at 950 psi Hydrogen gas) per incident proton is 1200. The measurement of beam position and profile are necessary. The MTA is a flammable gas (Hydrogen) hazard zone, so we have developed a passive beam diagnostic instrument using a Chromox-6 scintillation screen and CCD camera. This paper presents quantitative information about beam position and beam profile. A neutral density filter was used to avoid saturation of the CCD camera. Image data is filtered and fitted with a Gaussian function to compute the beam size. The beam profile obtained from the scintillation screen will be compared with a multi-wire beam profile.

MOPPR071

Initial Results of Transverse Beam Profile Measurements Using a LYSO:Ce Crystal

radiation, diagnostics, controls, laser

951

A.S. Johnson, A.H. Lumpkin, T.J. Maxwell, J. Ruan, J.K. Santucci, C.C. Tan, R.M. Thurman-Keup, M. Wendt
Fermilab, Batavia, USA

A prototype transverse beam profile monitor for eventual use at the Advanced Superconducting Test Accelerator (ASTA) has been tested at the Fermilab A0 Photoinjector. Results from low-charge (20 pC) studies indicate that a LYSO:Ce scintillator will be a viable replacement for a YAG:Ce scintillator when using intercepting radiation convertor screens for beam profiling. We will also describe the planned implementation of LYSO:Ce crystals to mitigate the coherent optical transition radiation due to the microbunching instability through the use of band-pass filters and specially timed cameras.

MOPPR073

Analysis of Resonant TE Wave Modulation Signals for Electron Cloud Measurements

resonance, coupling, factory, cavity

957

S. De Santis
LBNL, Berkeley, California, USA
D. Alesini
INFN/LNF, Frascati (Roma), Italy
J.P. Sikora
CLASSE, Ithaca, New York, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy under Contracts DE-FC02-08ER41538, DE-AC02-05CH11231.
Recent TE wave measurements of the electron cloud density in the beampipe at CesrTA and DAΦNE have shown that, especially near cutoff, the microwave excitation takes place by coupling to a standing wave, rather than to a propagating TE mode. With the beampipe acting as a resonant cavity, the effect of the periodic electron cloud density is a modulation of the cavity's resonant frequency. As a result, the measured sidebands are a combination of amplitude, phase, and frequency modulation, as the periodic cloud density modulates this resonant frequency. The quality factor Q of the resonance will determine its response to transients in the electron cloud density, and the resulting effect on modulation sidebands. In order to estimate the peak electron cloud density and its spacial distribution, knowledge of the Q and the standing wave pattern need to be determined, either by experimental measurements or simulation codes. In this paper we analyze the dependence of the modulation sidebands on the electron cloud density in two different regimes, when the cloud rise/decay time is much longer, or much shorter than the filling time of the resonance.

MOPPR074

Using TE Wave Resonances for the Measurement of Electron Cloud Density

resonance, cavity, simulation, vacuum

960

J.P. Sikora, M.G. Billing, D. L. Rubin, R.M. Schwartz
CLASSE, Ithaca, New York, USA
D. Alesini
INFN/LNF, Frascati (Roma), Italy
B.T. Carlson
CMU, Pittsburgh, Pennsylvania, USA
S. De Santis
LBNL, Berkeley, California, USA
K.C. Hammond
Harvard University, Cambridge, Massachusetts, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy under Contracts DE-FC02-08ER41538, DE-AC02-05CH11231.
In the past few years, electron cloud density has been measured by means of its effect on TE waves propagated through the accelerator vacuum chamber. This technique has been the object of careful studies and has been used in several laboratories around the world (CERN, SLAC, FNAL, Cornell, INFN-LNF). Recent measurements at CesrTA and DAΦNE show that in a majority of practical cases, the theoretical model that relates the cloud density to the phase shift induced on a TE wave propagating in beam pipe may not be the correct one. Instead, the measurement results have to be analyzed considering the effect of the electron cloud on a standing wave excited between the input and output couplers - typically Beam Position Monitors (BPMs). This standing wave pattern is not confined to the portion of beampipe between the BPMs and must be understood in order to correctly interpret the measurement. In this paper we present evidence that the transmission function near cutoff between two BPMs is the result of coupling to standing waves trapped in the vacuum chamber. This evidence includes measurements at DAΦNE, Cesr-TA, a test waveguide, computer EM simulations, and analytical calculations.

MOPPR075

Status of the APEX Beam Diagnostic and First Measurements

laser, diagnostics, cathode, gun

963

D. Filippetto, M.J. Chin, C.W. Cork, S. De Santis, L.R. Doolittle, W.E. Norum, C. F. Papadopoulos, G.J. Portmann, D.G. Quintas, F. Sannibale, R.P. Wells, M.S. Zolotorev
LBNL, Berkeley, California, USA

The APEX project aims to the construction of a high brightness high repetition rate photo-injector at LBNL. In its first phase a 750 keV electron bunch is produced at a maximum repetition rate of 1 MHz, with an adjustable charge per bunch spanning the pC-to-nC region. A load lock system is foreseen to test different cathodes without the need of breaking the vacuum and the downstream diagnostic is used to characterize the photo-emitted beam brightness. In the initial phase the main effort is directed toward the measurement of photocurrent, dark current, thermal emittance and electron beam kinetic energy. In a successive phase, diagnostic for full 6D phase space characterization of space charge dominated beams will be added to the beamline. We report and discuss the present diagnostic beamline layout, first beam measurements and future upgrades.

MOPPR080

Wire Scanner Beam Profile Measurements: LANSCE Facility Beam Development

controls, feedback, target, linac

975

J.D. Gilpatrick, Y.K. Batygin, F. Gonzales, M.E. Gruchalla, V.G. Kutac, D. Martinez, C. Pillai, S. Rodriguez Esparza, J.D. Sedillo, B.G. Smith
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the U.S. Department of Energy.
The Los Alamos Neutron Science Center (LANSCE) is replacing Wire Scanner (WS) beam profile measurement systems. Three beam development tests have taken place to test the new wire scanners under beam conditions. These beam development tests have integrated the WS actuator, cable plant, electronics processors and associated software and have used H⁻ beams of different beam energy and current conditions. In addition, the WS measurement-system beam tests verified actuator control systems for minimum profile bin repeatability and speed, checked for actuator backlash and positional stability, tested the replacement of simple broadband potentiometers with narrow band resolvers, and tested resolver use with National Instruments Compact Reconfigurable Input and Output (cRIO) Virtual Instrumentation. These beam tests also have verified how trans-impedance amplifiers react with various types of beam line background noise and how the cable plants can be simplified without generating unwanted noise currents. This paper will describe these beam development tests and show some resulting data.

MOPPR081

Wire Scanner Beam Profile Measurements for the LANSCE Facility

EPICS, controls, linac, LabView

978

J.D. Gilpatrick, M.E. Gruchalla, D. Martinez, C. Pillai, S. Rodriguez Esparza, J.D. Sedillo, B.G. Smith
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the U.S. Department of Energy.
The Los Alamos Neutron Science Center (LANSCE) is replacing beam profile measurement systems, commonly known as Wire Scanners (WS’s). Using the principal of secondary electron emission, the WS measurement system moves a wire or fiber across an impinging particle beam, sampling a projected multi-bin distribution. Because existing WS actuators and electronic components are either no longer manufactured or home-built with antiquated parts, a new wire scanner beam profile measurement is being designed, fabricated, and tested. The goals for these new wire scanner include using off-the-shelf components while eliminating antiquated components, providing quick operation while allowing for easy maintainability, and tolerating external radioactivation. The WS measurement system consists of beam line actuators, a simple cable plant, an electronics processor chassis, and software located both in the electronics chassis (National Instruments LabVIEW) and in the Central Control Room (EPICS-based software). This WS measurement system will measure the more common H⁻ and H⁺ LANSCE-facility beams and will also measure less common beams. This paper describes these WS measurement systems.

MOPPR087

Transverse Beam Emittance Measurements of a 16 MeV Linac at the Idaho Accelerator Center

quadrupole, emittance, linac, background

990

S. Setiniyaz, T.A. Forest
ISU, Pocatello, Idaho, USA
K. Chouffani, Y. Kim
IAC, Pocatello, IDAHO, USA
A. Freyberger
JLAB, Newport News, Virginia, USA

A beam emittance measurement of the 16 MeV S-band High Repetition Rate Linac (HRRL) was performed at Idaho State University's Idaho Accelerator Center (IAC). The HRRL linac structure was upgraded beyond the capabilities of a typical medical linac so it can achieve a repetition rate of 1 kHz. Measurements of the HRRL transverse beam emittance are underway that will be used to optimize the production of positrons using HRRL's intense electron beam on a tungsten converter. In this paper, we describe a beam imaging system using on an OTR screen and a digital CCD camera, a MATLAB tool to extract beamsize and emittance, detailed measurement procedures, and the measured transverse emittances for an arbitrary beam energy of 15 MeV.

MOPPR090

Progress Report on Development of a High Resolution Transverse Diagnostic based on Fiber Optics

diagnostics, radiation, photon, optics

996

R. Tikhoplav, R.B. Agustsson, G. Andonian, A.Y. Murokh, S. Wu
RadiaBeam, Santa Monica, USA
R.K. Li, P. Musumeci, C.M. Scoby
UCLA, Los Angeles, California, USA

A beam profile monitor utilizing the technological advances in fiber optic manufacturing to obtain micron level resolution is under development at RadiaBeam Technologies. This fiber-optic profiling device would provide a low cost, turn-key solution with nominal operational supervision and requires minimal beamline real estate. Preliminary results of Cherenkov light generation in fiber is presented.

TUXA02

Upgrade Plans for the LHC Injector Complex

linac, injection, vacuum, feedback

1010

R. Garoby, H. Damerau, S.S. Gilardoni, B. Goddard, K. Hanke, A.M. Lombardi, M. Meddahi, B. Mikulec, E.N. Shaposhnikova, M. Vretenar
CERN, Geneva, Switzerland

Challenging beams with much higher brightness than today are required for the LHC to achieve its high luminosity objective after the year 2020. It is the purpose of the LHC Injectors Upgrade (LIU) Project to achieve this result, consolidating and upgrading the existing set of ageing synchrotrons (PSB, PS and SPS), and using the new linac presently in construction (Linac4). The anticipated beam characteristics are described and compared to the known limitations in the different accelerators. The foreseen solutions are outlined as well as the planning for their implementation.

Slides TUXA02 [72.367 MB]

TUYA02

Overview of Asymmetric Electron Hadron Colliders

collider, ion, hadron, proton

1025

V. Ptitsyn
BNL, Upton, Long Island, New York, USA

The first lepton-proton collider HERA at DESY completed its operation in 2007. Presently, several accelerator proposals for future electron-hadron colliders are under consideration in several laboratories from all over the world. The future accelerators intend to exceed the HERA luminosity by 2-3 orders of magnitude, as well as to cover the different ranges of center-of-mass collision energies. The research capabilities will be extended by including the collisions of electrons with heavy ions, as well as, in some designs, with polarized protons and polarized ions. The future electron-hadron colliders would serve as high-resolution microscopes able to reveal unprecedented details of the structure of nucleons and ions, including their spin content and the state of high gluon density matter. The colliders will provide us with ultimate tools to test both the ways Quantum Chromodynamics works as well as to look for new physics beyond the Standard Model. All proposed electron-hadron colliders are based on the extension of existing accelerators to accommodate the electron-hadron collisions. Advanced accelerator technologies are utilized in order to achieve the desired high luminosity.

Slides TUYA02 [6.002 MB]

TUXB01

Progress Towards Ultimate Storage Ring Light Sources

emittance, brightness, dipole, wiggler

1035

M. Borland
ANL, Argonne, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Developments such as the low emittance NSLS-II storage ring, followed by the even lower emittance MAX-IV ring, demonstrate that the technology of storage ring light sources has not reached full maturity. Indeed, these new sources are paving the way toward realizing diffraction-limited angstrom-wavelength storage ring light sources in the not-too-distant future. Our discussion begins with a review of recent trends and developments in storage ring design. We then survey on-going work around the world to develop concepts and designs for so-called "ultimate" storage ring light sources.

Slides TUXB01 [3.442 MB]

TUXB02

Review of ERL Projects at KEK and Around the World

linac, gun, FEL, emittance

1040

N. Nakamura
KEK, Ibaraki, Japan

Future synchrotron light sources based on energy-recovery linacs (ERLs) are expected to be capable of producing super-brilliant and/or ultra-short pulses of synchrotron radiation. The Japanese collaboration team is making efforts for realizing an ERL-based VUV and X-ray source with R&D efforts on super-conducting cavities and the electron gun at KEK and elsewhere. This presentation will describe the developments of the compact ERL project and the outline of the 3-GeV ERL light source project at KEK and also review ERL projects around the world, including potential applications to colliders.

Slides TUXB02 [25.328 MB]

TUYB01

Proton Beam Acceleration with Circular Polarized Laser Pulses

laser, proton, plasma, ion

1045

X.Q. Yan, J.E. Chen, C. Lin, Y.R. Lu, H. Wang
PKU/IHIP, Beijing, People's Republic of China
Z.Y. Guo
IHEP, Beijing, People's Republic of China

This presentation should describe the use of circular polarized laser pulses for phase-stable acceleration of proton beams. The principles of the technique should be explained, with comparisons and contrasts made with similar techniques. The potential for production of high-intensity, mono-energetic proton beams should be discussed, and the results of analytical, simulation, and experimental studies presented.

Slides TUYB01 [7.922 MB]

TUYB02

Manufacture and Testing of Optical-scale Accelerator Structures from Silicon and Silica

laser, coupling, acceleration, vacuum

1050

R.J. England, E.R. Colby, R. Laouar, C. McGuinness, B. Montazeri, R.J. Noble, K. Soong, J.E. Spencer, D.R. Walz, Z. Wu
SLAC, Menlo Park, California, USA
R.L. Byer, C.M. Chang, K.J. Leedle, E.A. Peralta
Stanford University, Stanford, California, USA
B.M. Cowan
Tech-X, Boulder, Colorado, USA
M. Qi
Purdue University, West Lafayette, Indiana, USA

We report on recent progress in the design, manufacture and testing of optical-scale accelerator structures made from silicon and silica. The potential of these structures for the development of extremely compact, efficient, and low cost accelerators producing attosecond electron pulses will be discussed, together with various possible applications.

Slides TUYB02 [17.226 MB]

TUOAA01

3-Dimensional Modeling of Electron Clouds in Non-uniform Magnetic Fields

plasma, wiggler, simulation, resonance

1059

S.A. Veitzer, P. Stoltz
Tech-X, Boulder, Colorado, USA
J.A. Crittenden, K.G. Sonnad
CLASSE, Ithaca, New York, USA

Funding: This work was performed under the auspices of the Department of Energy as part of the ComPASS SCiDAC-2 project (DE-FC02-07ER41499) and by the National Science Foundation Grant PHY-0734867.
Electron clouds have the potential to pose serious limitations on accelerator performance in both hadron and lepton beams. Experiments using rf diagnostics are being performed to measure electron cloud densities at a number of accelerator facilities. However, it is difficult to calibrate plasma density with signal strength in these experiments, and modeling involves a number of technical and numerical challenges. Typically 2-Dimensional electrostatic methods have been used to model cloud buildup under beam crossing conditions. However, since traveling-wave rf experiments typically occur over many meters of beam pipe where magnetic fields are changing, one needs to develop 3-Dimensional electromagnetic models in order to accurately simulate rf diagnostics. We have developed accurate models of electron cloud-induced phase shifts in rf in a system with spatially varying magnetic field configurations using the plasma simulation code VORPAL. We present here results for measuring phase shifts in the CESR wiggler with realistic, spatially non-uniform magnetic field configurations.

Slides TUOAA01 [18.367 MB]

TUOBA01

Summary of Fermilab’s Recycler Electron Cooler Operation and Studies

antiproton, emittance, ion, extraction

1068

L.R. Prost, A.V. Shemyakin
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Fermilab’s Recycler ring was used as a storage ring for accumulation and subsequent manipulations of 8 GeV antiprotons destined for the Tevatron collider. To satisfy these missions, a unique electron cooling system was designed, developed and successfully implemented. The most important features that distinguish the Recycler cooler from other existing electron coolers are its relativistic energy (it employs a 4.3 MeV, 0.1 A DC electron beam), a weak continuous longitudinal magnetic field in the cooling section (~100 G), and lumped focusing elsewhere. With the termination of the collider operation at Fermilab, the cooler operation was also terminated. In this article, we will summarize the experience of commissioning, optimizing and running this unique machine over the 6 years of its existence.

Slides TUOBA01 [2.503 MB]

TUOAB02

Investigation of the Use of Silicon, Diamond and Liquid Helium Detectors for Beam Loss Measurements at 2 Kelvin

cryogenics, radiation, proton, interaction-region

1080

C. Kurfuerst, B. Dehning, W.T. Eisel, M. Sapinski
CERN, Geneva, Switzerland
V. Eremin
IOFFE, St. Petersburg, Russia
C. Fabjan
HEPHY, Wien, Austria

At the triplet magnets, close to the interaction regions of the LHC, the current Beam Loss Monitoring (BLM) system is very sensitive to the debris from the collisions. For future beams with higher energy and higher luminosity this will lead to a situation in which the BLM system can no longer distinguish between these interaction products and quench-provoking beam losses from the primary proton beams. The solution investigated is to locate the detectors as close as possible to the superconducting coil, i.e. the element to be protected. This means putting detectors inside the cold mass of the superconducting magnets at 1.9 K. As possible candidates for such loss monitors, diamond, silicon and a liquid helium chamber have been tested in a proton beam at liquid helium temperatures. The initial promising results from these tests will be presented and discussed in this contribution.

Slides TUOAB02 [3.412 MB]

TUOBB01

A European Proposal for the Compton Gamma-ray Source of ELI-NP

laser, photon, emittance, scattering

1086

L. Serafini, I. Boscolo, F. Broggi, V. Petrillo
Istituto Nazionale di Fisica Nucleare, Milano, Italy
O. Adriani, G. Graziani, G. Passaleva
INFN-FI, Sesto Fiorentino, Italy
S. Albergo, A. Tricomi
INFN-CT, Catania, Italy
D. Alesini, M.P. Anania, A. Bacci, R. Bedogni, M. Bellaveglia, C. Biscari, R. Boni, M. Boscolo, M. Castellano, E. Chiadroni, A. Clozza, E. Di Pasquale, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, F. Marcellini, C. Maroli, G. Mazzitelli, E. Pace, L. Pellegrino, R. Ricci, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, P. Tomassini, C. Vaccarezza, S. Vescovi, F. Villa
INFN/LNF, Frascati (Roma), Italy
D. Angal-Kalinin, J.A. Clarke, B.D. Fell, A.R. Goulden, J.D. Herbert, S.P. Jamison, P.A. McIntosh, R.J. Smith, S.L. Smith
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
P. Antici, M. Coppola, L. Lancia, A. Mostacci, L. Palumbo
URLS, Rome, Italy
N. Bliss, B.G. Martlew
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
P. Cardarelli, M. Gambaccini
INFN-Ferrara, Ferrara, Italy
L. Catani, A. Cianchi
INFN-Roma II, Roma, Italy
I. Chaikovska, O. Dadoun, A. Stocchi, A. Variola, Z.F. Zomer
LAL, Orsay, France
C. De Martinis
INFN/LASA, Segrate (MI), Italy
F. Druon, P. Fichot
ILE, Palaiseau Cedex, France
E. Iarocci
University of Rome "La Sapienza", Rome, Italy
M. Migliorati
Rome University La Sapienza, Roma, Italy
A.-S. Müller
IN2P3, Paris, France
V. Nardone
Università di Roma I La Sapienza, Roma, Italy
C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma), Italy
M. Veltri
Uniurb, Urbino (PU), Italy

A European proposal is under preparation for the Compton gamma-ray Source of ELI-NP. In the Romanian pillar of ELI (the European Extreme Light Infrastructure) an advanced gamma-ray beam is foreseen, coupled to two 10 PW laser systems. The photons will be generated by Compton back-scattering in the collision between a high quality electron beam and a high power laser. A European collaboration formed by INFN, Univ. of Roma La Sapienza, Orsay-LAL of IN2P3, Univ. de Paris Sud XI and ASTeC at Daresbury, is preparing a TDR exploring the feasibility of a machine expected to achieve the Gamma-ray beam specifications: energy tunable between 1 and 20 MeV, narrow bandwidth (0.3%) and high spectral density, 10⁴ photons/sec/eV. We will describe the lay-out of the 720 MeV RF Linac and the collision laser with the associated optical cavity, as well as the optimized beam dynamics to achieve maximum phase space density at the collision, taking into account beam loading and beam break-up due to the acceleration of long bunch trains. The predicted gamma-ray spectra will be evaluated as the gamma photons collimators background. An option for electron bunches recirculation will also be illustrated.

Slides TUOBB01 [5.099 MB]

TUOBB03

Status of the FERMI@Elettra Project

FEL, laser, radiation, photon

1092

M. Svandrlik, E. Allaria, L. Badano, S. Bassanese, F. Bencivenga, E. Busetto, C. Callegari, F. Capotondi, D. Castronovo, M. Coreno, P. Craievich, I. Cudin, G. D'Auria, M. Dal Forno, M.B. Danailov, R. De Monte, G. De Ninno, A.A. Demidovich, M. Di Fraia, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, L. Fröhlich, P. Furlan Radivo, G. Gaio, L. Giannessi, R. Gobessi, C. Grazioli, E. Karantzoulis, M. Kiskinova, M. Lonza, B. Mahieu, C. Masciovecchio, S. Noè, F. Parmigiani, G. Penco, E. Principi, F. Rossi, L. Rumiz, C. Scafuri, S. Spampinati, C. Spezzani, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, M. Zaccaria, D. Zangrando, M. Zangrando
ELETTRA, Basovizza, Italy

Funding: The work was supported in part by the Italian Ministry of University and Research under grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3.
The FERMI@Elettra seeded Free Electron Laser has provided the first photons to the experimental stations during 2011. The first FEL line in operation is FEL-1, covering the wavelength range between 100 nm and 20 nm. The facility will be opened to users by the end of 2012. In the meantime the installation of the second FEL line, FEL-2 covering the higher energy range down to 4 nm, is progressing on schedule and first tests have started. A description of the status of the project is presented here.

Slides TUOBB03 [5.316 MB]

TUOBC03

Experimental Measurements of e-Cloud Mitigation using Clearing Electrodes in the DAΦNE Collider

positron, vacuum, wiggler, dipole

1107

D. Alesini, T. Demma, A. Drago, A. Gallo, S. Guiducci, C. Milardi, P. Raimondi, M. Zobov
INFN/LNF, Frascati (Roma), Italy
S. De Santis
LBNL, Berkeley, California, USA

Recently the electron-positron collider DAΦNE has started delivering luminosity to the KLOE-2 experiment. For this run special metallic electrodes for e-cloud clearing were installed in all the dipole and wiggler magnets of the collider positron ring. Experimental measurements of the effectiveness of the electrodes in the mitigation of the e-cloud effects in the positron beam have been done showing an impressive effectiveness of these devices in the cure of the e-cloud effects in the positron beam. In particular the electrodes allow reducing the vertical beam size increase, the growth rate of transverse instabilities and the tune shifts induced by the electron cloud. Frequency shifts measurements of the vacuum chamber resonances switching on and off the electrodes have also been done showing their effect in the reduction of the electron cloud density. In this paper we summarize the results of all our observations and the experimental measurements of the e-cloud suppression with these electrodes.

Slides TUOBC03 [2.825 MB]

TUEPPB001

Interaction of Muon Beam with Plasma Developed During Ionization Cooling

plasma, wakefield, simulation, collider

1110

S. Ahmed
JLAB, Newport News, Virginia, USA
K.B. Beard, T.J. Roberts
Muons, Inc, Batavia, USA
D.M. Kaplan, L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Muon collider has been envisioned as a future high energy lepton machine. High luminosity can be obtained by the ionization cooling – best suited for muons due to their short life time. In this cooling process, particles ionize material medium in which they lose momentum, thus the normalized emittance is reduced. The ionized medium is called plasma and the ionization density could increase due to the passage of multiple bunches through the material. This means that the incoming beams interact with plasma together with ionizing the medium used for cooling. It is, therefore, important to investigate the effects of background plasma on the incoming bunches. A comprehensive studies of muon beam propagation through plasma medium using EM particle-in-cell simulations. This computational study involves kinetic model, therefore, provides deep insight of the phenomena, which cannot be obtained by the conventional fluid model. The wakes excited by mu+ and mu- are different due to the beam polarity and depends on their relative densities. Externally applied axial magnetic field suppresses the wakes evolved during the interaction. The details of this study will be discussed in the paper.

TUEPPB002

Numerical Simulations of Transverse Beam Diffusion Enhancement by the Use of Electron Lens in the Tevatron Collider

simulation, resonance, collider, beam-beam-effects

1113

V. Previtali, G. Stancari, A. Valishev
Fermilab, Batavia, USA
D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia

Funding: "Fermi Research Alliance, LLC operates Fermilab under Contract DE-AC02-07CH11359 with the US Department of Energy. This work was partially supported by the US LHC Accelerator Research Program (LARP)."
Transverse beam diffusion for the Tevatron machine has been calculated using the Lifetrac code. The following effects were included: random noise (representing residual gas scattering, voltage noise in the accelerating cavities) lattice nonlinearities and beam-beam interactions. The time evolution of particle distributions with different initial amplitudes in Hamiltonian action has been simulated for 6 million turns, corresponding to a machine time of about 2 minutes. For each particle distribution, several cases have been considered: a single beam in storage ring mode, the collider case, and the effects of a hollow electron beam collimator

TUEPPB005

Novel Technique of Suppressing TBBU in High-energy ERLs

linac, HOM, SRF, lattice

1122

V. Litvinenko
BNL, Upton, Long Island, New York, USA

Energy recovery linacs (ERLs) is emerging generation of accelerators promising revolutionize the fields of high-energy physics and photon sciences. One potential weakness of these devices is transverse beam-breakup instability, which may severely limit available beam current. In this paper I am presenting novel idea of using natural chromaticity in ERL arcs to suppressing TBBU instabilities. I present the theory of the process and two exact cases demonstrating that the threshold of TBBU instability could be raised by my orders of magnitude using this method.
* V.N. Litvinenko, Chromaticity of the lattice and beam stability in energy recovery linacs, submitted to PR ST-AB

TUEPPB006

Direct Numerical Modeling of E-Cloud Driven Instability of Three Consecutive Batches in the CERN SPS

simulation, emittance, feedback, betatron

1125

J.-L. Vay, M.A. Furman, M. Venturini
LBNL, Berkeley, California, USA

Funding: Supported by the US-DOE under Contract DE-AC02-05CH11231, the SciDAC program ComPASS and the US-LHC Accelerator Research Program (LARP).
Electron clouds impose limitations on current accelerators that may be more severe for future machines, unless adequate measures of mitigation are taken. The simulation package WARP-POSINST was recently upgraded for handling multiple bunches and modeling concurrently the electron cloud buildup and its effect on the beam, allowing for direct self-consistent simulation of bunch trains generating, and interacting with, electron clouds. We have used the WARP-POSINST package on massively parallel supercomputers to study the buildup and interaction of electron clouds with a proton bunch train in the CERN SPS accelerator. Results suggest that a positive feedback mechanism exists between the electron buildup and the e-cloud driven transverse instability, leading to a net increase in predicted electron density.
Used resources of NERSC.

TUEPPB009

First Measurements of the FACET Coherent Terahertz Radiation Source

radiation, diagnostics, photon, insertion

1134

Z. Wu, E. Adli, A.S. Fisher, M.J. Hogan, H. Loos
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
The Facility for Accelerator science and Experimental Tests (FACET) at SLAC provides a high peak current, sub-ps bunched beam that is ideal for THz photon generation via coherent transition radiation. This paper presents preliminary characterization of the THz pulses generated by FACET electron beam. A one-micron thick Ti foil has been inserted into the beam path and the radiated photons collected. Michelson spectroscopy yields frequency content spanning from 0.25 THz to 2.3 THz and peaked at around 0.5 THz. Multiple scans at different bunch compression show a monotonic increase of the peak radiation frequency as the electron bunch gets shorter. Using the Kramers-Kronig relation, the temporal profile of the THz pulse is reconstructed from the power spectrum indicating a ~4 picosecond main pulse followed by a long oscillating tail due to the water absorption lines and detector response. Knife-edge scans measure a 4.4 mm x 4.8 mm transverse spot size at the focal point of the THz optical path. The total collected energy per pulse is 0.69 mJ measured by a Joulemeter. Fitting this total energy to the spatiotemporal profile of the THz pulse yields peak e-field amplitude of 1.5 MV/cm.

TUEPPB010

Oscillator Seeding of a High Gain Harmonic Generation FEL in a Radiator-first Configuration

FEL, radiation, laser, bunching

1137

P.R. Gandhi, J.S. Wurtele
UCB, Berkeley, California, USA
G. Penn, M.W. Reinsch
LBNL, Berkeley, California, USA

A longitudinally coherent X-ray pulse from a high repetition rate free electron laser (FEL) is desired for a wide variety of experimental applications. However, generating such a pulse with a repetition rate greater than ~1 MHz is a significant challenge. The desired high rep rate sources, primarily high harmonic generation with intense lasers in gases or plasmas, do not exist now, and, for the multi-MHz bunch trains that superconducting accelerators can potentially produce, are likely not feasible with current technology. In this paper, we propose to place an oscillator downstream of a radiator. The oscillator generates radiation that is used as a seed for a high gain harmonic generation (HGHG) FEL which is upstream of the oscillator. For the first few pulses the oscillator builds up power and, until power is built up, the radiator has no HGHG seed. As power in the oscillator saturates, the HGHG is seeded and power is produced. The dynamics and stability of this radiator-first scheme is explored analytically and numerically. A single-pass map is derived using a semi-analytic model for FEL gain and saturation. Iteration of the map is shown to be in good agreement with simulations.

TUEPPB011

Echo Enabled High Mode Generation for X-ray FELs

laser, bunching, FEL, free-electron-laser

1140

E. Hemsing
SLAC, Menlo Park, California, USA
A. Marinelli
UCLA, Los Angeles, California, USA

Funding: Work supported by U.S. DOE under Contract Nos. DE-AC02-76SF00515 and DE-FG02-07ER46272.
We describe a simple technique based on a modified echo-enabled harmonic generation (EEHG) scheme to manipulate the three-dimensional electron beam microbunching distribution in order to generate higher-order optical modes in an FEL. As with EEHG, the concept uses two modulators and two chicanes to produce microbunching. However, in one of the modulators, the resonant interaction with the laser has a well-defined transverse structure that becomes strongly correlated to the longitudinal microbunching distribution. Both high-harmonic frequencies and high transverse mode numbers can be generated through a transversely-dependent echo effect.

TUEPPB013

Development of an Advanced Computational Tool for Start-to-End Modeling of Next Generation Light Sources

radiation, simulation, wakefield, undulator

1143

J. Qiang, J.N. Corlett, C.E. Mitchell, C. F. Papadopoulos, G. Penn, R.D. Ryne, M. Venturini
LBNL, Berkeley, California, USA

Funding: Work supported by the Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Start-to-end simulation plays an important role in designing next generation light sources. In this paper, we present recent progress in further development and application of the parallel beam dynamics code, IMPACT, towards the fully start-to-end, multi-physics simulation of a next generation X-ray FEL light source. We will discuss numerical methods and physical models used in the simulation. We will also present some preliminary simulation results of a beam transporting through photoinjector, beam delivery system, and FEL beamlines.

TUEPPB015

Generation of Narrow-Band Coherent Tunable Terahertz Radiation using a Laser-Modulated Electron Beam

laser, radiation, undulator, bunching

1146

M.P. Dunning, C. Hast, E. Hemsing, R.K. Jobe, D.J. McCormick, J. Nelson, T.O. Raubenheimer, K. Soong, Z.M. Szalata, D.R. Walz, S.P. Weathersby, D. Xiang
SLAC, Menlo Park, California, USA

Funding: Work supported by US DOE contract DE-AC02-76SF00515.
The technical layout and initial results of an experiment to generate narrow-band, coherent, tunable terahertz (THz) radiation through the down-conversion of the frequency of optical lasers using a laser-modulated electron beam are described. In this experiment a 120 MeV electron beam is first energy modulated by two lasers with different wavelengths. After passing through a dispersive section, the energy modulation is converted into a density modulation at THz frequencies. This density-modulated beam will be used to generate narrow-band THz radiation using a coherent transition radiator inserted into the beam path. The central frequency of the THz radiation can be tuned by varying the wavelength of one of the two lasers or the energy chirp of the electron beam. The experiment is being performed at the NLCTA at SLAC, and will utilize the existing Echo-7 beamline, where echo-enabled harmonic generation (EEHG) was recently demonstrated.

TUPPC007

Electron Cloud Dynamics in a Gabor Space Charge Lens

space-charge, plasma, ion, focusing

1164

K. Schulte, M. Droba, B. Glaeser, S. Klaproth, O. Meusel, U. Ratzinger
IAP, Frankfurt am Main, Germany

Inside Gabor space charge lenses, external fields confine electrons forming a homogeneously distributed electron cloud. Its linear electric space charge field enables the focusing of high intensity heavy ion beams without aberrations. The focusing performance depends on the properties of the non-neutral plasma. In a small-scale table top experiment, different types of space charge lenses are used to characterize the collective behavior of the confined electron cloud using new non-interceptive diagnostic methods. The plasma parameters, e.g. electron temperature and density, are important to an improved understanding of loss and production mechanisms as well as the electron cloud dynamics. In this context, the evolution of instabilities caused by the enclosing fields has been investigated in detail. Experimental results will be presented and compared to numerical simulations.

TUPPC009

Dihedral Group and Repetitive Achromats with Mirror Symmetric or Mirror Antisymmetric Basic Cell

multipole, resonance, focusing, free-electron-laser

1170

V. Balandin, R. Brinkmann, W. Decking, N. Golubeva
DESY, Hamburg, Germany

Using the group-theoretical point of view for the design of magnetic optical achromats as introduced in*, we study in this paper second- and third-order repetitive achromats with a mirror symmetric or mirror antisymmetric basic cell. We also compare these achromats with repetitive achromats designed without internal cell symmetries taken into account.
* V.Balandin, R.Brinkmann, W.Decking, N.Golubeva. Two Cell Repetitive Achromats and Four Cell Mirror Symmetric Achromats, Proceedings of IPAC'10, Kyoto, Japan.

TUPPC015

Local Modification of Lattice of a Long Straight Section for Installing Small Gap In-vacuum Undulators at SPring-8

lattice, betatron, dynamic-aperture, sextupole

1188

K. Soutome, T. Fujita, K. Fukami, K.K. Kaneki, C. Mitsuda, H. Ohkuma, M. Oishi, Y. Okayasu, S. Sasaki, J. Schimizu, Y. Shimosaki, M. Shoji, M. Takao, Y. Taniuchi, C. Zhang
JASRI/SPring-8, Hyogo-ken, Japan
M. Hasegawa, K. Kajimoto, T. Nakanishi
SES, Hyogo-pref., Japan

In the SPring-8 storage ring there are four magnet-free long straight sections (LSS) of about 30m. Recently we locally modified one of these sections by installing two quadrupole-triplets and divided it into three sub-sections. The vertical beta at the middle of each sub-section was lowered to 2.5m so that small gap in-vacuum undulators with a short period (min. gap: 5.2mm, period: 19mm) can be installed to build a high performance beamline for inelastic X-ray scattering. After modifying the lattice, however, the symmetry of the ring is lowered and, in general, it becomes difficult to keep sufficient dynamic aperture (DA) and momentum acceptance (MA). We solved this problem by combining the betatron phase matching, local chromaticity correction in LSS and cancellation of non-linear kicks due to sextupoles used for this correction. We could then recover DA and MA to almost the same level for the original one. The beam commissioning of the new lattice has successfully been finished, and from September 2011 it is used in user-operation. We will report our method of realizing a storage ring lattice having a very low symmetry and review the operation performance of the modified lattice.

TUPPC024

R&D of an Ultrafast Probe Apparatus Based on MeV Electron Diffraction at Tsinghua University

solenoid, simulation, emittance, cathode

1215

X.H. Lu, Y.-C. Du, W.-H. Huang, H.J. Qian, C.-X. Tang
TUB, Beijing, People's Republic of China

Funding: This work is supported by National Natural Science Foundation of China and National Basic Research Program of China (973 Program).
An ultrafast probe apparatus based on MeV ultrafast electron diffraction is developed at Tsinghua University. It aims at generating 1.5 to 3 MeV pulse with sub-pC charge and sub-ps pulse length for pump-probe experiments. It consists of an S-band 1.6-cell radiofrequency photocathode gun, a solenoid, a sample chamber, a deflecting cavity, a detection system and other diagnostics tools. Simulations show the position of solenoid coil affects the spot size on detection screen and the charge of collimated bunch significantly. The collimator is found to be helpful to stabilize the charge of collimated bunch and reduce its normalized emittance. The construction of the apparatus is almost finished and the commissioning test will start soon.

TUPPC027

Multi Objective Genetic Optimization for Linac Lattice of PAL XFEL

linac, lattice, emittance, quadrupole

1224

C.H. Yi, M.-H. Cho, S.H. Kim, W. Namkung
POSTECH, Pohang, Kyungbuk, Republic of Korea
H.-S. Kang
PAL, Pohang, Kyungbuk, Republic of Korea
K.-J. Kim
ANL, Argonne, USA

Funding: Work supported by MEST and POSTECH Physics BK21 Program.
There are a large number of variables and objectives in design of XFEL linac lattices. Recently, most of accelerator physics field, are applying the multi-objective genetic algorithm (MOGA) for these kinds of problems. MOGA was applied to the PAL XFEL linac lattice design. Longitudinal position of all components was fixed before applying MOGA. RF parameters of RF cavities and bending angles of bunch compressors are selected as variables. Various beam parameters computed by ELEGANT were used as objectives. By using MOGA, new linac lattice designs with 2 and 3 bunch compressors was generated and their beam properties are presented in this paper.

TUPPC036

Integration with the LHC of Electron Interaction Region Optics for a Ring-ring LHeC

quadrupole, proton, dipole, optics

1239

L.N.S. Thompson
Cockcroft Institute, Warrington, Cheshire, United Kingdom
R. Appleby
UMAN, Manchester, United Kingdom
N.R. Bernard
ETH, Zurich, Switzerland
H. Burkhardt, B.J. Holzer
CERN, Geneva, Switzerland
M. Fitterer
KIT, Karlsruhe, Germany
M. Klein
The University of Liverpool, Liverpool, United Kingdom
P. Kostka
DESY Zeuthen, Zeuthen, Germany

The Large Hadron Electron Collider (LHeC) project is a proposal to study e-p and e-A interactions at the LHC. One design uses an electron synchrotron to collide a 60GeV e± beam with the 7TeV proton beam. Designing a new accelerator around the existing LHC machine poses unique challenges, particularly in the interaction region (IR). The electron beam must be quickly separated from the proton beam after the interaction point (IP) to avoid beam-beam effects, while not significantly reducing luminosity or producing large amounts of synchrotron radiation. The proton beam must pass through the electron optics, while the electron beam must avoid the proton optics. The long straight section requires bending in both planes to counteract the IP crossing angle and to displace the beam vertically from the electron machine to the proton IP. An achromatic bending scheme is used in the vertical plane to eliminate dispersion at the IP and provide an optics which is well matched to the LHeC ring lattice. The interaction region and long straight section design is presented and detailed, and the design process and principles discussed.

TUPPC038

Interaction Region Optics for the Non-Interacting LHC Proton Beam at the LHeC

proton, optics, quadrupole, synchrotron

1245

L.N.S. Thompson
Cockcroft Institute, Warrington, Cheshire, United Kingdom
R. Appleby
UMAN, Manchester, United Kingdom
O.S. Brüning, B.J. Holzer
CERN, Geneva, Switzerland
M. Klein
The University of Liverpool, Liverpool, United Kingdom
P. Kostka
DESY Zeuthen, Zeuthen, Germany

The Large Hadron Electron Collider project is a proposal to study e-p and e-A interactions at the LHC. Two electron accelerator designs are being studied; a linac and a synchrotron. In the synchrotron option, a 60GeV electron beam is collided with one of the LHC proton beams to provide high luminosity TeV-scale interactions. The interaction region for this scheme is complex and introduces a series of challenges due to the integration of the two machines. One of these is the optics of the second non-interacting proton beam. The second proton beam must not interfere with the LHeC experiment, but simultaneous running of the remaining LHC experiments requires that this beam must still circulate relatively undisturbed. This paper discusses methods to solve these challenges for the electron synchrotron design.

TUPPC039

Synchrotron Radiation Studies for a Ring-Ring LHeC Interaction Region and Long Straight Section

dipole, proton, quadrupole, synchrotron

1248

L.N.S. Thompson
Cockcroft Institute, Warrington, Cheshire, United Kingdom
R. Appleby
UMAN, Manchester, United Kingdom
N.R. Bernard
ETH, Zurich, Switzerland
O.S. Brüning, B.J. Holzer
CERN, Geneva, Switzerland
M. Klein
The University of Liverpool, Liverpool, United Kingdom
P. Kostka
DESY Zeuthen, Zeuthen, Germany
B. Nagorny
DESY, Hamburg, Germany

The Large Hadron Electron Collider project is a proposal to study e-p and e-A interactions at the LHC. In the design for an electron synchrotron (alternative designs for a linac are also under development), a 60GeV e± beam is collided with a 7TeV LHC proton beam to produce TeV-scale collisions. Despite being much lower energy than the proton beam, the electron beam is high enough energy to produce significant amounts of synchrotron radiation (SR). This places strong constraints on beam optics and bending. In particular challenges arise with the complex geometry required by the long straight section (LSS) and interaction region (IR). This includes the coupled nature of the proton and electron optics, as SR produced by the electron beam must not be allowed to quench the superconducting proton magnets or create problems with beam-gas backgrounds. Despite this, the electron beam must be deflected significantly within the IR to produce sufficient separation from the proton beam.

TUPPC045

Modeling Investigation on a Deflecting-Accelerating Composite RF-cavity System for Phase Space Beam Control

cavity, coupling, simulation, klystron

1266

Y.-M. Shin, M.D. Church, P. Piot
Fermilab, Batavia, USA

Phase space manipulations between the longitudinal and transverse degree of freedoms hold great promise toward the precise control of electron beams. Such transverse-to-longitudinal phase space exchange have been shown to be capable of exchanging the transverse and horizontal emittance or controlling the charge distribution of an electron bunch, for beam-driven advanced accelerator methods. The main limitation impinging on the performance of this exchange mechanism stems from the external coupling nature of a realistic deflecting cavity, compared to a thin-lens model. As an extended idea from *, this paper presents the design of a composite 3.9-GHz RF-system consisting of a deflecting- and accelerating-mode cavities. The system design analysis is discussed with particle-in-cell (PIC) simulations of the device performance.
* A. Zholents, PAC'11.

TUPPC046

Further Analysis of Real Beam Line Optics from a Synthetic Beam

optics, coupling, linac, closed-orbit

1269

R.M. Bodenstein
UVa, Charlottesville, Virginia, USA
Y. Roblin, M.G. Tiefenback
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S. Government retains a license to publish or reproduce this manuscript for U.S. Government purposes.
Standard closed-orbit techniques for Twiss parameter measurement are not applicable to the open-ended Continuous Electron Beam Accelerator Facility (CEBAF) at Jefferson Lab. The evolution of selected sets of real orbits in the accelerator models the behavior of a “synthetic” beam. This process will be validated against beam profile-based Twiss parameter measurements and should provide the distributed optical information needed to optimize beamline tuning for an open-ended system. This work will discuss the current and future states of this technique, as well as an example of its use in the CEBAF machine.

TUPPC054

Beam Acceleration by a Multicell RF Cavity Structure Proposed for Improved Yield in Hydroforming

cavity, acceleration, quadrupole, focusing

1293

J.A. Holmes, Y.W. Kang
ORNL, Oak Ridge, Tennessee, USA
A.E. Fathy, K.R. Shin
University of Tennessee, Knoxville, Tennessee, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
We study the accelerating properties of a new multicell cavity structure with irises forming a rectangular aperture between the cavity cells. We are interested in this structure because, from a mechanical point of view, the rectangular iris may make possible a much improved structure quality using a hydroforming manufacturing process. RF analysis shows that the rectangular iris shape provides asymmetric transverse focusing per half RF period. If the horizontal and vertical rectangular irises are interleaved, the net transverse focusing can be increased. The present studies of the acceleration and transport properties of these cavities are conducted by tracking particles through time-dependent 3D cavity fields from CST MWS using the ORBIT Code.

TUPPC067

How to Achieve Longitudinally Polarized Electrons using Integer Spin Tune Resonances

polarization, resonance, synchrotron, dipole

1326

O. Boldt, A. Dieckmann, F. Frommberger, W. Hillert, J.F. Schmidt
ELSA, Bonn, Germany

Funding: Bundesministerium für Bildung und Forschung
Commonly, strong solenoids are used in circular accelerators to achieve longitudinal polarization. In practice, however, these solenoids cause a phase space coupling, which has to be compensated for by sophisticated decoupling schemes. We suggest to adiabatically ramp into an integer spin tune resonance, while preserving the degree of polarization. When appropriately adjusting the driving horizontal field contributions at the final energy, the resulting polarization is longitudinal at predefined positions in the accelerator. Here, depending on the energy spread, the degree of polarization is conserved for several seconds. The contribution shows the numerical analysis of this scenario being confirmed by first demonstration tests at the ELSA stretcher ring.

TUPPC074

Study of Resonance Driving Term in Electron Storage Rings

damping, radiation, resonance, storage-ring

1344

G. Liu, W. Li, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

The resonance driving term (RDT) is useful to analyze and optimize the nonlinear performance of the storage ring. In addition to analytical calculation of RDT, experimental measurement of RDT has been made in some proton storage rings based on turn-by-turn BPM data. For electron storage rings, the analysis is more complicated due to decoherence effects and strong radiation damping. The relation between spectral decomposition of BPM data and RDT is derived and validated using beam numerical tracking data in this paper.

TUPPC075

Study of Nonlinear Beam Dynamics Effects for DEPU at SSRF

polarization, undulator, photon, focusing

1347

M. Zhang, Q.G. Zhou
SINAP, Shanghai, People's Republic of China

A pair of EPUs (DEPU) with the period 58mm and 148mm, covering the energy ranges from 20 to 200eV and 200 to 2000eV of arbitrary polarized light, will be developed for the SSRF soft X-ray beam line for ARPES and PEEM. The effects of DEPU to tune-shift produced by the nonlinear beam dynamics are studied and the results are presented in this paper. The corresponding magnet field shimming technology to reduce these effects is also investigated.

TUPPC094

Experimental Observations of Large-amplitude Solitary Waves in Electron Beams

space-charge, laser, longitudinal-dynamics, gun

1377

Y. Mo, B.L. Beaudoin, D.W. Feldman, I. Haber, R.A. Kishek, P.G. O'Shea
UMD, College Park, Maryland, USA
J.C.T. Thangaraj
Fermilab, Batavia, USA

Funding: Work funded by the US Dept. of Energy Offices of Fusion Energy Sciences and High Energy Physics and Fusion Energy Sciences, and by the Dept. of Defense Office of Naval Research.
The longitudinal dynamics of space charge dominated beams plays an important role in particle accelerators and other applications such as heavy ion fusion and free electron lasers (FELs). All beams are space-charge dominated near the source. Furthermore, the longitudinal profile is not necessarily an ideal mathematical function. By means of experiments on the University of Maryland Electron Ring (UMER), we studied how a perturbation to the line charge density could affect the beam propagation. By varying the initial amplitude of the perturbation, we access nonlinear space charge physics. When starting with large-amplitude perturbations, we have observed, for the first time in charged particle beams, solitary waves for which the nonlinear steepening exactly balances the wave dispersion, leading to persistent waves that preserves their shape over a long distance. This paper presents the results of the soliton experiments, including systematic studies of the dependence of the soliton propagation on beam current, perturbation level and width. The data is compared with theory and simulation.

TUPPC097

Computational Modeling of Electron Cloud For MEIC

simulation, collider, ion, emittance

1383

S. Ahmed, J.D. Dolph, G.A. Krafft, T. Satogata, B.C. Yunn
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
This work is the continuation of our earlier studies on electron cloud (EC) simulations reported in IPAC'11 for the medium energy electron-ion collider (MEIC) envisioned at JLab beyond the 12 GeV upgrade of CEBAF. In this paper, we will study the EC saturation density in various MEIC operations scenarios to calculate details of the EC-induced wakefield to establish more stringent bounds on instability thresholds and determine whether EC mitigation, such as NEG coatings or solenoid fields, should be considered in the MEIC design.

TUPPC098

Electron Polarization in the Medium-Energy Electron-Ion Collider at JLAB

polarization, solenoid, dipole, closed-orbit

1386

F. Lin, Y.S. Derbenev, V.S. Morozov, Y. Zhang
JLAB, Newport News, Virginia, USA
D.P. Barber
DESY, Hamburg, Germany

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A key feature of the Medium-energy Electron-Ion Collider (MEIC) at Jefferson Lab is high polarization (over 80%) of the electron beam at all collision points for the particle physics program. The equilibrium electron polarization is arranged to be vertical in the arcs of the figure-8 collider ring of the MEIC and anti-parallel to the arc dipole magnetic fields, in order to take advantage of the preservation of polarization by the Sokolov-Ternov (S-T) effect. Longitudinal polarization is achieved at collision points by utilizing energy-independent universal spin rotators each of which consists of a set of solenoids and dipoles placed at the end of an arc. The equilibrium beam polarization and its lifetime depend on competition between the S-T effect and radiative depolarization. The latter must be suppressed by spin matching. This paper reports on investigations of polarization in the MEIC electron collider ring and a preliminary estimate of beam polarization from calculations using the code SLICK.
Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.

TUPPC103

Ion Bunch Length Effects on the Beam-beam Interaction and its Compensation in a High-luminosity Ring-ring Electron-ion Collider

proton, luminosity, ion, simulation

1401

C. Montag, W. Fischer, A. Oeftiger
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
One of the luminosity limits in a ring-ring electron-ion collider is the beam-beam effect on the electrons. In the limit of short ion bunches, simulation studies have shown that this limit can be significantly increased by head-on beam-beam compensation with an electron lens. However, with an ion bunch length comparable to the beta-function at the IP in conjunction with a large beam-beam parameter, the electrons perform a sizeable fraction of a betatron oscillation period inside the long ion bunches. We present recent simulation results on the compensation of this beam-beam interaction with multiple electron lenses.

TUPPD020

An EMMA Racetrack

dipole, quadrupole, injection, extraction

1452

B.D. Muratori, J.K. Jones
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H.L. Owen
UMAN, Manchester, United Kingdom

EMMA (Electron Machine for Many Applications) is the world’s first prototype non-scaling electron FFAG hosted at Daresbury Laboratory. Several upgrade possibilities for EMMA are explored, from creating a dispersion-free region in the ring to facilitate injection and extraction to making an insertion in EMMA by turning it into a racetrack-style machine. Alternative methods of injection and extraction into the EMMA ring are explored together with their feasibility and implications. The option of developing nested racetracks to achieve a particular desired energy is also explored.

TUPPD032

Design Optimization of Flux Concentrator for SuperKEKB

positron, solenoid, simulation, target

1473

L. Zang, S. Fukuda, T. Kamitani, Y. Ogawa
KEK, Ibaraki, Japan

For high luminosity electron-positron colliders, intense positron beam production is one of the key issues as well as electron. Flux Concentrator (FC) is a pulsed solenoid that can generate high magnetic field of several Tesla and is often used for focusing positrons emerged from a production target. It works as an optical matching device in a positron capture section. With this device, high capture efficiency is achieved. In this paper, we will discuss a design optimization of a FC for the SuperKEKB positron source. Geometrical parameters of the FC are optimized to achieve high peak field using the CST EM Studio. Magnetic field distribution evaluated with the EM Studio is implemented into a particle tracking code to see a performance of the positron capture section. The tracking simulation includes a positron production at the target, focusing by the FC and subsequent solenoids and acceleration by RF structures till the end of the capture section. We report the results of a FC design optimized for higher positron yield with the tracking simulation.

TUPPD033

Conceptual Design of a Positron-annihilation System for Generation of Quasi-monochromatic Gamma Rays

positron, target, photon, dipole

1476

R.J. Abrams, C.M. Ankenbrandt, K.B. Beard, G. Flanagan, R.P. Johnson, C. Y. Yoshikawa
Muons, Inc, Batavia, USA
A. Afanasev
GWU, Washington, USA

A conceptual design is presented for a system consisting of the following: an electron accelerator and production target to produce positrons, a dipole magnet and wedge to compress the positron momenta to be nearly monochromatic, a magnetic transport system to focus and direct the positrons to a converter, and a converter in which the positrons annihilate in flight to produce quasi-monochromatic gamma rays. The system represented is designed to produce ~10 MeV gammas, but it can also be designed for other energies.

TUPPD034

Multi-bunch Beam Generation by Photo-cathode RF Gun for KEK-STF

cavity, laser, gun, cathode

1479

M. Kuriki, S. Hosoda, H. Iijima
HU/AdSM, Higashi-Hiroshima, Japan
A. Ayaka
Sokendai, Ibaraki, Japan
H. Hayano, J. Urakawa, K. Watanabe
KEK, Ibaraki, Japan
G. Isoyama, R. Kato, K. Kawase
ISIR, Osaka, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
K. Sakaue
RISE, Tokyo, Japan

Funding: MEXT, Quantum beam project.
KEK-STF is doing R&D of Super-Conducting (SC) accelerator technology for ILC (International Linear Collider), based on 1.3 GHz RF system. For STF and ILC, the pulse length is 1ms and the repetition is 5Hz. We developed a L-band Normal-Conducting RF gun designed by DESY to provide electron beam over such long pulse duration. For NC Photo-cathode RF gun, such high duty and long pulse operation is a challenging task, because the detuning by the heat load of cavity dissipation power is significant. The RF gun provides the electron pulse train to SC accelerator modules which will be operated at 31.5 MV/m gradient. Precise RF control is essential for SC accelerator because the beam loading and input RF power should be well ballanced for a stable operation. The beam test to demonstrate the stable opeation is very important for SC accelerator R&D. The system is also used to demonstrate high-flux quasi-monochromatic X-ray generation by inverse Compton scattering at KEK-STF. The experiment is carried out from April 2012 to November 2012 at KEK-STF. We report the latest status of the multi-bunch generation by the RF gun.

TUPPD037

Simulation Study of the Effect of the Proton Layer Thickness on TNSA

plasma, proton, simulation, laser

1488

L. Lecz
TEMF, TU Darmstadt, Darmstadt, Germany
O. Boine-Frankenheim, V. Kornilov
GSI, Darmstadt, Germany

The LIGHT project is a collaboration of several laser and accelerator laboratories in Germany with the purpose to consolidate the theoretical, numerical and experimental investigations for the usage of laser accelerated ions in the conventional accelerators. The central facility is the PHELIX laser at GSI, Darmstadt, with a strong-field solenoid as a collimation and transport device. This contribution is devoted to the numerical investigation of the proton acceleration via the TNSA mechanism using 1D and 2D particle-in-cell electro-magnetic simulations. The phase-space distribution of the accelerated protons and co-moving electrons, which is necessary for further transport studies, is investigated for different parameters of the thin hydrogen-rich contamination layer on the rear target surface. Depending on the layer thickness the protons can be accelerated in different regimes, from the quasi-static acceleration for mono-layers up to the isothermal plasma expansion for thick layers.

TUPPD043

Resonant Reaction with a Superintense Circulating Beam

target, proton, resonance, storage-ring

1497

V.G. Dudnikov, C.M. Ankenbrandt
Muons, Inc, Batavia, USA

A system for efficient generation of resonance reaction in the interaction of the circulating ion beam with a thin internal target is considered. Features of this system are high intense space charge compensated circulating ion beam with an intensity greater then a space charge limit in a near integrable nonlinear focusing system. Ionization energy loss is compensated by inductive electric field. Multiple scattering and energy straggling are compensated by electron cooling with a tabular electron beam. In this method it is possible to compensate an energy loss of circulating particles after crossing the target and have a crossing of resonant energy in every passing of target. For sharp resonance reactions and monoenergetic beams a thin target method can increase greatly the energy efficiency.

TUPPD045

Efficient Plasma Generation by Positive Circulating Beams

ion, proton, vacuum, plasma

1503

V.G. Dudnikov, C.M. Ankenbrandt
Muons, Inc, Batavia, USA

Performances of high brightness circulating beams are affected by development of strong “electron-proton” (e-p) instabilities connected with generation of an electron cloud (EC). For suppression of the EC generation it is proposed a coating of vacuum chambers by compounds with low secondary electron emission, which is very complex and expensive for large systems like LHC or RHIC. Threshold beam intensity for EC generation can be increased during the vacuum chamber bombarding by plasma particles generating by EC. Vacuum chamber processing (scrubbing) by EC is conducted by bunched beam with a highest possible intensity and with shortest gaps between bunches. Highly efficient plasma generation can be produced in the coasting circulating beam of positive particles with relative low intensity and energy. With the coasting positive beam the plasma particles are generating by low energy electrons trapped by a positive beam space charge. Dynamics of electrons and ions generation will be estimated and simulated. The rate of plasma generation and surface scrubbing can be increase by decrease of pumping and injection of selected gases.

TUPPD050

Investigation of Laser-cleaning Process on Lead Photocathodes

laser, cathode, photon, high-voltage

1515

S.G. Schubert, R. Barday, T. Kamps, T. Quast, A. Varykhalov
HZB, Berlin, Germany
R. Nietubyć
The Andrzej Soltan Institute for Nuclear Studies, Centre Świerk, Świerk/Otwock, Poland
F. Siewert
BESSY GmbH, Berlin, Germany
J. Smedley
BNL, Upton, Long Island, New York, USA
G. Weinberg
FHI, Berlin, Germany

Funding: Work supported by Bundesministerium für Bildung und Forschung and Land Berlin.
Metal photocathodes are widely used in electron injectors due to their stability and long life time; unfortunately they exhibit low quantum efficiency. Due to adsorption of contaminants the work function increases and thus the quantum efficiency is further reduced. In order to increase the quantum efficiency of our Pb cathode we performed a cleaning procedure by means of a high power excimer laser as suggested by Smedley*. The process was studied on witness samples in a combined photo emission, SEM and quantum efficiency measurement study. Thin Lead films were arc-deposited on optical polished Mo-substrates**. Before and after irradiation the sample was analyzed at 140 eV photon energy at a XPS/ARPES end station at the synchrotron radiation source Bessy II. We followed the change of the Pb 5d signals. In the initial situation we observed signals originating from metallic Pb and Pb in the oxidized state, respectively. Since the surface roughness is of concern for the injector performance it was examined before and after the irradiation procedure with white-light-interferometry and the surface morphology by means of SEM.
*J. Smedley et al, PRST-AB 11, 013502 (2008).
** Rao, T. et al., IPAC 2010, THPEC020 (2010).

TUPPD052

A New Load Lock System for the Source of Polarized Electrons at ELSA

vacuum, polarization, laser, ion

1521

D. Heiliger, W. Hillert, B. Neff
ELSA, Bonn, Germany

Funding: supported by DFG (SFB/TR16)
Since 2000, an inverted source of polarized electrons at the electron stretcher accelerator ELSA routinely provides a pulsed beam with a current of 100 mA and a polarization degree of about 80%. One micro-second long pulses with 100 nC charge are produced by irradiating a GaAs strained-layer superlattice photocathode (8 mm in diameter) with laser light. Future accelerator operation requires a significantly higher beam intensity, which can be achieved by using photocathodes with sufficiently high quantum efficiency. Therefore, and in order to enhance the reliability and up time of the source, a new extreme high-vacuum (XHV) load lock system was installed and commissioned at the beginning of this year. It consists of three chambers: The activation chamber for heat cleaning of the photocathodes and activation with cesium and oxygen. The storage chamber in which up to five different types of photocathodes with various diameters of the emitting surface can be stored under XHV conditions. The loading chamber in which an atomic hydrogen source is used to remove any remaining surface oxidation. Additionally, tests of the photocathodes’ properties can be performed during operation.

TUPPD054

Research Activities on Photocathodes for HZDR SRF Gun

gun, cathode, SRF, vacuum

1524

R. Xiang
FZD, Dresden, Germany
A. Arnold, M. Freitag, P. Michel, P. Murcek, J. Teichert
HZDR, Dresden, Germany

Funding: We acknowledge the support of the European Community-Research Infrastructure Activity (EuCARD, contract number 227579), as well German Federal Ministry of Education and Research grant 05 ES4BR1/8.
Since 2005 the photocathode laboratory has been in operation at HZDR. The main goal is to prepare Cs2Te photocathodes for the SRF gun. A vacuum transport system with UHV is used to move the cathodes from preparation lab to accelerator hall. Up to now 31 Cs2Te photocathodes have been deposited and eight of them have been used in the SRF gun. Quantum efficiency of 1% and lifetime of months can be maintained during the gun operation. At the same time activities are directed towards new photocathode materials with high Q.E. for high current electron sources. Cs3Sb and GaN(Cs) photocathodes have been tested as new candidates, and the design of a preparation system for GaAs(Cs, O) is ongoing.

TUPPD058

Development of an RF Electron Gun for Ultra-Short Bunch Generation

gun, cavity, cathode, simulation

1536

Y. Koshiba, T. Aoki, K. Sakaue, M. Washio
RISE, Tokyo, Japan
T. Takatomi, J. Urakawa
KEK, Ibaraki, Japan

At Waseda University, various researches are done using a photocathode rf electron gun with a 1.6 cell cavity. Now we are developing a new rf cavity specialized for producing an ultra-short electron bunch, with the collaboration of High Energy Accelerator Research Organization (KEK). We have used SUPERFISH for designing the new rf cavity and PARMELA for beam tracking. The new rf cavity has an extra cell following the 1.6 cell. The extra cell can chirp the energy of electron bunch so we call it ECC (Energy Chirping Cell). ECC chirp the energy because we shortened the length of iris just before the ECC and also the length of ECC itself. Moreover, electric field in ECC is made to be stronger than others. We have confirmed on PARMELA that ECC rf gun can generate an 100pC electron bunch less than 200fsec with the energy of 4.5MeV at about 2.5m away from the cathode. Such an ultra-short electron bunch enables us to generate a coherent terahertz light using ultra-short electron bunch by synchrotron radiation or transition radiation. In this conference, we would like to introduce the detail of the design of this new ECC rf gun, the present progresses and future prospects.

TUPPD061

High-Power RF Test of an RF-Gun for PAL-XFEL

gun, laser, emittance, injection

1539

J.H. Hong, J.H. Han, H.-S. Kang, C. Kim, S.H. Kim, C.-K. Min, S.S. Park, S.J. Park, Y.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea
M.S. Chae, I.S. Ko, Y.W. Parc
POSTECH, Pohang, Kyungbuk, Republic of Korea

A photocathode RF-gun for the X-ray free electron laser (XFEL) at the Pohang Accelerator Laboratory (PAL) has been fabricated and tested at PAL. This RF-gun is based on a 1.6-cell cavity with dual-feed waveguide ports and two pumping ports. The RF gun was designed by PAL and POSTECH. The RF-gun has been successfully tested with a cathode electric field gradient up to 126MV/m at a repetition rate of 30 Hz. This paper reports the recent results on the beam test of the RF-gun with high power RF at the gun test facility. We present and discuss the measurements of the basic beam parameters such as charge, energy, energy spread, and transverse emittance.

TUPPD067

Experimental Facility for Measuring the Electron Energy Distribution from Photocathodes

cathode, vacuum, brightness, laser

1557

L.B. Jones, R.J. Cash, B.D. Fell, J.W. McKenzie, K.J. Middleman, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H.E. Scheibler, A.S. Terekhov
ISP, Novosibirsk, Russia

ASTeC have spent several years developing a GaAs Photocathode Preparation Facility (PPF) which routinely produces cathodes with quantum efficiencies (Q.E.) up to 20% at 635 nm*. The goal is to use these cathodes in high-average-current high-brightness injectors for particle accelerators. Electron injector brightness is driven by photocathode emittance, and brightness will be increased significantly by reducing the longitudinal and transverse energy spread. We are constructing an experimental system for measurement of the horizontal and transverse energy spreads at room and LN₂-temperature which accepts photocathodes from the PPF. The sample will be illuminated by a small, variable-wavelength light spot. The beam image will be projected onto a detector comprised of 3 grids which act as an energy filter, a micro-channel plate and a phosphor screen. A low-noise CCD camera will capture screen images, and the electron distribution and energy spread will be extracted through analysis of these images as a function of the grid potentials. The system will include a leak valve to progressively degrade the cathode, and thus allow its properties to be measured as a function of Q.E.
* Proc IPAC ’11, THPC129 (2011).

TUPPD068

Design of the Production and Measurement of Ultra-Short Electron Bunches from an S-band RF Photoinjector

cavity, gun, dipole, laser

1560

J.W. McKenzie, D. Angal-Kalinin, J.K. Jones, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The Electron Beam Test Facility (EBTF) is planned for installation in late 2012 at Daresbury Laboratory. An S-band RF photoinjector provides ultrashort, low emittance electron bunches up to 6 MeV. A suite of diagnostics has been designed to fully characterise the bunches. A particular focus has been on producing and measuring bunch lengths less than 100 fs. This can be achieved with a multi-cell standing wave S-band transverse deflecting cavity. Operating such a cavity with low energy electrons provides certain challenges which are discussed in this paper with respect to beam dynamic simulations.

TUPPD070

Kelvin Probe Studies of a Cesium Telluride Photocathode for the AWA Photoinjector

cathode, vacuum, photon, wakefield

1566

E.E. Wisniewski, K.C. Harkay, Z.M. Yusof
ANL, Argonne, USA
L.K. Spentzouris, J. Terry, D.G. Velazquez, E.E. Wisniewski
Illinois Institute of Technology, Chicago, Illinois, USA

Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for the new Argonne Wakefield Accelerator (AWA) to produce high charge per bunch (~50 nC). Here, we present a study of the "work function" of a cesium telluride photocathode using the Kelvin Probe technique. The study includes an investigation of the correlation between the quantum efficiency and the work function, the effect of photocathode aging, the surprising effect of UV exposure on the work function, and the puzzling behavior of the work function during and after photocathode rejuvenation via heating.

TUPPD071

Development of Cesium Telluride Photocathodes for the AWA Accelerator Upgrade

wakefield, vacuum, acceleration, cathode

1569

Z.M. Yusof, M.E. Conde, W. Gai
ANL, Argonne, USA
L.K. Spentzouris, E.E. Wisniewski
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: U.S. Department of Energy Office of Science under Contract No. DE-AC02-06CH11357.
Cesium telluride photocathodes have been fabricated for the Argonne Wakefield Accelerator (AWA) upgrade. The as-deposited photocathodes have consistently produced quantum efficiency values better than 10% with 254 nm light source and with variation of less than 5% over a circular area of 1.2 inches in diameter. We present various characterizations of the photocathode that have performed, including rejuvenation, lifetime, and performance in the L-band AWA photoinjector.

TUPPD080

Design of Ultrafast High-Brightness Electron Source

cathode, gun, brightness, laser

1587

J.H. Park, H. Bluem, J. Rathke, T. Schultheiss, A.M.M. Todd
AES, Princeton, New Jersey, USA

Funding: This work was supported by the U.S. Department of Energy, under Contract No. DE-SC0006210.
Generation and preservation of ultrafast electron beams is one of the major challenges in accelerator R&D. Space charge forces play a fundamental role in emittance dilution and bunch lengthening for all high brightness beams. In order to generate and preserve the ultrafast high-brightness electron beam, transverse and longitudinal space charge effects have to be considered. Several approaches to achieving ultra-short bunches have been explored such as velocity bunching and magnetic compression. However, each option suffers drawbacks in achieving a compact ultrafast high-brightness source. We present an alternative scheme to achieve an ultrafast high-brightness electron beam using a radial bunch compression technique in an x-band photocathode RF electron gun. By compensating the path length difference with a curved cathode and using an extremely high acceleration gradient (greater than 200 MV/m), we seek to deliver 100 pC, 100 fsec bunches.

TUPPD081

Development of Carbon NanoTube (CNT) Cathodes at RadiaBeam

cathode, vacuum, gun, high-voltage

1590

L. Faillace, R.B. Agustsson, S. Boucher, A.Y. Murokh, A.V. Smirnov
RadiaBeam, Santa Monica, USA

RadiaBeam is developing Carbon Nanotube (CNT) cathodes for DC-pulsed and radio frequency (RF) driven electron sources. CNT cathodes, if realized, are capable of producing very high current density with low thermal emittance, due to ambient operating temperature. The initial experimental results of CNT cathodes are presented, including the high-voltage tests, and life time studies. CNT cathodes potential applications in accelerator science and microwave industry are discussed, and near term plans to test the CNT cathodes in the RF environment are presented.

TUPPD082

Simulations of Multipacting in the Cathode Stalk and FPC of 112 MHz Superconducting Electron Gun

cathode, gun, simulation, niobium

1593

T. Xin, X. Liang
Stony Brook University, Stony Brook, USA
S.A. Belomestnykh, I. Ben-Zvi, T. Rao, J. Skaritka, E. Wang, Q. Wu
BNL, Upton, Long Island, New York, USA
X. Chang
Far-Tech, Inc., San Diego, California, USA

Funding: Work is supported at BNL by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE. The work at Stony Brook is supported by the US DOE under grant DE-SC0005713.
A 112 MHz superconducting quarter-wave resonator electron gun will be used as the injector of the Coherent Electron Cooling (CEC) proof-of-principle experiment at BNL. Furthermore, this electron gun can be used for testing of the performance of various high quantum efficiency photocathodes. In a previous paper, we presented the design of the cathode stalks and a Fundamental Power Coupler (FPC). In this paper we present updated designs of the cathode stalk and FPC. Multipacting in the cathode stalk and FPC was simulated using three different codes, Multipac, CST particle studio and FishPact respectively. All simulation results show no serious multipacting in the cathode stalk structure and FPC.

TUPPD083

Raising Photoemission Efficiency with Surface Acoustic Waves

photon, polarization, linac, vacuum

1596

A. Afanasev, F. Hassani, C.E. Korman
GWU, Washington, USA
V.G. Dudnikov, R.P. Johnson
Muons, Inc, Batavia, USA
M. Poelker, K.E.L. Surles-Law
JLAB, Newport News, Virginia, USA

Funding: Supported in part by DOE STTR Grant DE-SC0006256. Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
We are developing a novel technique that may help increase the efficiency and reduce costs of photoelectron sources used at electron accelerators. The technique is based on the use of Surface Acoustic Waves (SAW) in piezoelectric materials, such as GaAs, that are commonly used as photocathodes. Piezoelectric fields produced by the traveling SAW spatially separate electrons and holes, reducing their probability of recombination, thereby enhancing the photoemission quantum efficiency of the photocathode. Additional advantages could be increased polarization provided by the enhanced mobility of charge carriers that can be controlled by the SAW and the ionization of optically-generated excitons resulting in the creation of additional electron-hole pairs. It is expected that these novel features will reduce the cost of accelerator operation. A theoretical model for photoemission in the presence of SAW has been developed, and experimental tests of the technique are underway.

TUPPP005

LUNEX5: A French FEL Test Facility Light Source Proposal

FEL, laser, emittance, undulator

1611

A. Loulergue, C. Benabderrahmane, M. Bessière, P. Betinelli-Deck, F. Bouvet, A. Buteau, L. Cassinari, M.-E. Couprie, J. Daillant, J.-C. Denard, P. Eymard, B. Gagey, C. Herbeaux, M. Labat, A. Lestrade, P. Marchand, J.L. Marlats, C. Miron, P. Morin, A. Nadji, F. Polack, J.B. Pruvost, F. Ribeiro, J.P. Ricaud, P. Roy
SOLEIL, Gif-sur-Yvette, France
S. Bielawski, C. Evain, C. Szwaj
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
B. Carré
CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France
G. Devanz, M. Luong
CEA/DSM/IRFU, France
L. Farvacque, G. Lebec
ESRF, Grenoble, France
G. Lambert, A. Lifschitz, V. Malka, A. Rousse
LOA, Palaiseau, France
M. Le Parquier
CERLA, Villeneuve d'Ascq, France
J. Lüning
CCPMR, Paris, France
R. Roux
LAL, Orsay, France

LUNEX5 is a new synchrotron FEL source project aiming at delivering short and coherent X-ray pulses to probe ultrafast phenomena at the femto-second scale, to investigate extremely low density samples as well as to image individual nm scale objects. The proposed machine layout is based on a 400 MeV super-conducting Conventional Linear Accelerator (CLA) mainly composed of 2 XFEL type cryo-modules together with a normal-conducting high brightness photo RF gun. This present mature and reliable technology is able to deliver high quality electron bunches up to few kHz suitable for user experiments. Further more, the last decade improvement in synchronization and stability offer a fertile land to explore the different and innovative seeded FEL operations aiming at producing higher coherence and energetic X-rays for the pilot user full benefits. In parallel of the CLA branch, the very promising and highly innovative Laser Wake-Field Accelerator (LWFA) able to produce very short electron bunches in the range of the femto-second and high peak current up to few GeV is foreseen as a FEL bench test using the same undulator lines.

TUPPP008

Recent Results From the Short-Pulse Facility at the DELTA Storage Ring

laser, radiation, undulator, synchrotron

1617

A. Schick, M. Bakr, H. Huck, M. Höner, S. Khan, R. Molo, A. Nowaczyk, P. Ungelenk, M. Zeinalzadeh
DELTA, Dortmund, Germany

Funding: Work supported by DFG, BMBF and by the Federal State NRW.
At the 1.5 GeV synchrotron light source DELTA, operated by the TU Dortmund University, a new facility for ultrashort pulses in the VUV and THz regime is currently under commissioning. Here, the interaction of an intense, ultrashort laser pulse, co-propagating with the electrons in an optical klystron, leads to coherent synchrotron radiation at harmonics of the incident laser wavelength. The aim of the present commissioning steps is to extend the emitted wavelength down to about 50 nm, enabling femtosecond-resolved pump-probe experiments in the VUV regime. Other issues include increasing the photon flux by optimizing the laser-electron interaction and improving the stability and ease of operation of the source.

TUPPP026

RF Rescue Option for TPS Linac

linac, bunching, booster, injection

1668

K.L. Tsai, H.-P. Chang, C.-T. Chen, C.-S. Fann, K.T. Hsu, S.Y. Hsu, K.-K. Lin, H.M. Shih
NSRRC, Hsinchu, Taiwan
K. Dunkel, C. Piel
RI Research Instruments GmbH, Bergisch Gladbach, Germany

The 150 MeV linac of Taiwan Photon Source was commissioned in June 2011. It consists of 90 keV electron source, bunching system and three S-band accelerating sections driven by three high-power klystrons. The rf system is equipped with rescue option such that the rf power from second klystron can be split and fed into both accelerating section 1 and 2. The rescue operation will be needed in the event of a failure occurred at the first klystron. In the report, the rescue capability will be illustrated and the test results will also be discussed.

TUPPP031

Modelling the Steady-state CSR Emission in Low Alpha Mode at the Diamond Storage Ring

wakefield, impedance, factory, bunching

1677

I.P.S. Martin, C.A. Thomas
Diamond, Oxfordshire, United Kingdom
R. Bartolini
JAI, Oxford, United Kingdom

The CSR emitted by short electron bunches can be of a stable or bursting nature, with transition between the two states characterised by a threshold current that depends on various machine parameters. Key to understanding this process is to develop an effective model that describes the way the electron bunch interacts with impedance sources such as the CSR wakefield and surrounding vacuum chamber. In this paper we present the latest results of modelling the equilibrium distribution calculated using the Haissinski equation driven by different impedance models. The bunch lengthening with current, bunch profiles and CSR form factors derived from this model are compared to measured data for both positive and negative momentum compaction factor. Comparisons of the measured bursting thresholds to theoretical predictions are also discussed.

TUPPP036

Large-scale Simulation of Synchrotron Radiation using a Lienard-Wiechert Approach

radiation, simulation, synchrotron, synchrotron-radiation

1689

R.D. Ryne, C.E. Mitchell, J. Qiang
LBNL, Berkeley, California, USA
B.E. Carlsten, N.A. Yampolsky
LANL, Los Alamos, New Mexico, USA

Funding: DOE Office of Science, Office of Basic Energy Sciences; NNSA.
Synchrotron radiation is one of the most important and difficult to model phenomena affecting lepton accelerators. Large-scale parallel modeling provides a means to explore properties of synchrotron radiation that would be impossible to study through analytical methods alone. We have performed first-principles simulations of synchrotron radiation, using a Lienard-Wiechert approach, with the same number of simulation particles as would be found in bunches with charge up to 1 nC. The results shed light on the importance of shot noise effects, the amplification of coherent synchrotron radiation due to longitudinal microbunching, the interplay of electric and magnetic forces, and the limits of the widely used one-dimensional model.

TUPPP045

Creation of FELWI using Large Amplification Regime

undulator, FEL, resonance, microtron

1707

K.B. Oganesyan
ANSL, Yerevan, Armenia
A.I. Artemyev, D.N. Klochkov
GPI, Moscow, Russia
Y. Rostovtsev
University of North Texas, Denton, Texas, USA

Funding: ISTC project A-1602
The interaction between noncollinear laser and relativistic electron beams in static magnetic undulator has been studied within the framework of dispersion equations. In the limit of small-signal gain the spatial growth rates are found for the collective (Raman) and single-electron (Thompson) regimes. For a free-electron laser without inversion (FELWI), estimates of the threshold laser power are found. The large-amplification regime should be used to bring an FELWI above the threshold laser power.

TUPPP050

FEL Performances of the French LUNEX5 Project

FEL, laser, bunching, undulator

1712

C. Evain, S. Bielawski
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
C. Benabderrahmane, M.-E. Couprie, C. Evain, M. Labat, A. Loulergue
SOLEIL, Gif-sur-Yvette, France
G. Lambert, A. Lifschitz, V. Malka
LOA, Palaiseau, France

LUNEX5 is a french FEL test facility project based on two types of accelerators: a 400 MeV Conventional Linear Accelerator (CLA) and a Laser WakeField Accelerator (LWFA). The FEL performances will be presented at 20 nm and at 12 nm, wavelengths of interest for the pilot experiments. Results are obtained with GENESIS simulations in time-dependent mode. With the CLA, we compare different seeded schemes as EEHG scheme (Echo Enabled Harmonic Generation) or HGHG scheme (High Gain Harmonic Generation) using HHG source (High Harmonic in Gaz). In parallel, LWFA FEL performances will be presented as a function of the electron bunch characteristics, in particular the bunch length and the energy-spread. The transport of the LWFA output beams into undulators which is found to be a critical issue will be also discussed.

TUPPP052

Status of FLASH

FEL, photon, laser, undulator

1715

K. Honkavaara, B. Faatz, J. Feldhaus, S. Schreiber, R. Treusch, M. Vogt
DESY, Hamburg, Germany

FLASH at DESY (Hamburg, Germany) is a free-electron laser user facility driven by a superconducting 1.25 GeV linac based on TESLA technology. During the 3rd user period from September 2010 to September 2011, totally 3740 hours of FEL radiation has been delivered to FEL experiments at more than 30 different wavelengths between 4.7 nm and 45 nm. In addition, beam time has been dedicated to general accelerator physics studies and developments related to the future projects like the European XFEL and the International Linear Collider. After a 3.5 months shutdown in autumn 2011 due to civil construction for a second undulator beamline - FLASH2 - and a following commissioning and study period, 2012 is mainly dedicated to FEL user experiments. This paper summarizes the operation status of the FLASH facility and gives also a short review of the accelerator studies carried out in 2011 and early 2012. The mid-term plans including FLASH2 are presented as well.

TUPPP053

Investigations on the Optimum Accelerator Parameters for the Ultra-Short Bunch Operation of the Free-Electron Laser in Hamburg (FLASH)

laser, emittance, simulation, space-charge

1718

M. Rehders, J. Rönsch-Schulenburg, J. Roßbach
Uni HH, Hamburg, Germany
T. Limberg, H. Schlarb, S. Schreiber
DESY, Hamburg, Germany

Funding: The project is supported by the Federal Ministry of Education and Research of Germany (BMBF) under contract No. 05K10GU2 and FSP301.
In order to produce the shortest possible radiation pulses using Free Electron Lasers like FLASH, various possibilities have been proposed during the last decade. Probably the most robust method is the generation of electron bunches that in the most extreme case are as short as a single longitudinal optical mode of the SASE (Self-Amplified Spontaneous Emission) radiation. For FLASH this means that the bunch length has to be a few fs only. As a consequence, very low bunch charges (in the order of 20 pC) have to be used. To achieve these extremely short bunch lengths, a new photo-injector laser has been installed, which allows for the generation of shorter electron bunches right at the cathode. Simulations of the electron bunches and their six-dimensional phase-space distribution have been performed to investigate the optimum accelerator parameters during injection and to determine how to realize them. First results are discussed in this contribution.

TUPPP056

Study of the Energy Chirp Effects on Seeded FEL Schemes at SDUV-FEL

FEL, radiation, laser, undulator

1724

C. Feng, D. Wang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

Seeded free-electron laser (FEL) schemes hold great promise for generation of high brilliant radiation with a narrow bandwidth. Analysis with the idealized electron beam with constant current and energy indicate that both the high-gain harmonic generation (HGHG) and the echo-enabled harmonic generation (EEHG) can produce Fourier-transform limited radiation pulses. However, residual energy variations due to nonlinearity of the accelerator or energy modulations due to microbunching instability will be unavoidable and may broaden the bandwidth of the seeded FEL. In this paper, we study the energy chirp effects on both the HGHG and EEHG schemes. Analytic and simulation calculations are presented and compared with the experimental data. Results show that the coherence properties of the EEHG FEL may not be degraded by the energy chirp when properly choosing the parameters of the dispersion sections.

TUPPP059

Effects of Metal Mirrors Reflectivity and Aberrations on THz FEL Radiation Performance

FEL, cavity, radiation, undulator

1729

P. Tan, T. Yu
HUST, Wuhan, People's Republic of China
M. Fan, Q. Fu, D. Li, B. Qin, Y.Q. Xiong, Y.B. Yibin
Huazhong University of Science and Technology (HUST), Wuhan, People's Republic of China

The primary design study of terahertz free-electron laser (FEL) is presented in this paper. The effects of optical cavity parameter, metal mirrors reflectivity and aberrations on the THz FEL radiation performance have been explored. The reflectivity characteristics of copper, silver and gold are tested in terahertz region. The effects of metal mirrors reflectivity and aberrations on the THz FEL radiation performance are studied by numerical simulation.

TUPPP061

Status of the PAL-XFEL Project

undulator, linac, gun, FEL

1735

J.H. Han, H.-S. Kang, I.S. Ko
PAL, Pohang, Kyungbuk, Republic of Korea

Funding: The Ministry of Education, Science and Technology of the Korean Government
PAL-XFEL is designed to generate X-ray radiation in the range of 0.1 and 10 nm for users. The machine consists of a 10 GeV linear accelerator and five undulator beamlines. Electron beams are generated at a low emittance S-band photocathode RF gun and accelerated with an S-band normal conducting linac. Three hard X-ray beamlines will be located at the end of the linac. Electron beams for two soft X-ray beamlines will be switched at a medium energy. The project started in 2011 and the building construction is ongoing. Resent progress of the project and an update of the current progress are presented.

TUPPP063

Electron-beam Optimization Studies for the FERMI@Elettra Free-electron Laser

linac, emittance, simulation, alignment

1741

E. Ferrari, G. De Ninno
University of Nova Gorica, Nova Gorica, Slovenia
P. Craievich, S. Di Mitri, E. Ferrari, L. Fröhlich, G. Gaio, G. Penco, C. Spezzani, M. Trovò
ELETTRA, Basovizza, Italy

FERMI@Elettra is a single-pass free-electron laser, based on seeded high-gain harmonic generation. Presently, the first phase of the project (covering the spectral range between 100 and 20 nm) is under commissioning. The free-electron laser performance depends on the quality of the electron beam. In the case of the FERMI linear accelerator, the latter is strongly influenced both by the wake-fields present in the accelerating sections and by possible misalignments of the various accelerator components. In order to investigate and compensate these effects, we performed a study based on local trajectory bumps. We demonstrate that this approach significantly improves the electron-beam quality and, eventually, the free-electron laser performance.

TUPPP066

CLARA - A Proposed New FEL Test Facility for the UK

FEL, laser, undulator, diagnostics

1750

J.A. Clarke, D. Angal-Kalinin, D.J. Dunning, S.P. Jamison, J.K. Jones, J.W. McKenzie, B.L. Militsyn, N. Thompson, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R. Bartolini
JAI, Oxford, United Kingdom
I.P.S. Martin
Diamond, Oxfordshire, United Kingdom

A new single pass national FEL test facility, CLARA, is proposed to be constructed at Daresbury Laboratory in the UK. The aim of CLARA is to develop a normal conducting test accelerator able to generate longitudinally and transversely bright electron bunches and to use these bunches in the experimental production of stable, synchronized, ultra short photon pulses of coherent light from a single pass FEL with techniques directly applicable to the future generation of light source facilities. In addition the facility will be an ideal test bed for demonstrating innovative technologies such as high repetition rate normal conducting RF linacs and advanced undulator designs. This paper will describe the design of CLARA, pointing out the flexible features that will be incorporated to allow multiple novel FEL schemes to be proven.

TUPPP067

Collimation System Design and Performance for the SwissFEL

collimation, undulator, linac, wakefield

1753

F. Jackson, J.-L. Fernández-Hernando
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
D. Angal-Kalinin
Cockcroft Institute, Warrington, Cheshire, United Kingdom
H.-H. Braun, S. Reiche
Paul Scherrer Institut, Villigen, Switzerland

Electron beam collimation in the SwissFEL is required for protection of the undulators against radiation damage and demagnetization. The design for the SwissFEL collimation for the hard X-ray undulator (Aramis) includes transverse collimation in the final accelerating linac sections, plus an energy collimator in a post-linac chicane. The collimation system must provide efficient protection of the undulator for various machine modes providing varied final beam energy to the undulator. The performance of the transverse and energy collimation design is studied in simulations including evaluation of the transverse collimation for various beam energies and the effect of grazing particles on the energy collimator. Collimator wakefields are also considered.

TUPPP069

A Compact, Modular Electron Beam Delay Line for Use in Novel Free-Electron Laser Schemes

undulator, quadrupole, FEL, lattice

1759

J.K. Jones, J.A. Clarke, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Two Free-Electron Laser (FEL) schemes have been proposed, for the generation of attosecond pulse trains* and for the improvement of the longitudinal coherence of SASE FELs**, in which repeated electron delays are implemented within the undulator lattice. To obtain the maximum performance and flexibility from these schemes it is advantageous to use an electron delay line that satisfies the isochronicity conditions, as well as being compact, modular and, ideally, variable. In this paper we present initial designs for such a system, along with simulations of its performance. We investigate both in-undulator and out-of-undulator designs, and compare the applicability of each for various aspects of the FEL design, as well as commenting on the mechanical and magnetic implications of the schemes.
* N.R. Thompson and B.W.J. McNeil. Phys. Rev. Lett. 100, 203901 (2008).
** N.R. Thompson, D.J. Dunning and B.W.J. McNeil, IPAC2010, TUPE050, p. 2257 (2010).

TUPPP070

Next Generation Light Source R&D and Design Studies at LBNL

FEL, linac, laser, gun

1762

J.N. Corlett, B. Austin, K.M. Baptiste, D.L. Bowring, J.M. Byrd, S. De Santis, P. Denes, R.J. Donahue, L.R. Doolittle, P. Emma, D. Filippetto, G. Huang, T. Koettig, S. Kwiatkowski, D. Li, T.P. Lou, H. Nishimura, H.A. Padmore, C. F. Papadopoulos, G.C. Pappas, G. Penn, M. Placidi, S. Prestemon, D. Prosnitz, J. Qiang, A. Ratti, M.W. Reinsch, D. Robin, F. Sannibale, D. Schlueter, R.W. Schoenlein, J.W. Staples, C. Steier, C. Sun, T. Vecchione, M. Venturini, W. Wan, R.P. Wells, R.B. Wilcox, J.S. Wurtele
LBNL, Berkeley, California, USA

Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
LBNL is developing design concepts for a multi-beamline soft x-ray FEL array powered by a superconducting linear accelerator, operating with a high bunch repetition rate of approximately one MHz. The cw superconducting linear accelerator is supplied by an injector based on a high-brightness, high-repetition-rate photocathode electron gun. Electron bunches are distributed from the linac to the array of independently configurable FEL beamlines with nominal bunch rates up to 100 kHz in each FEL, and with even pulse spacing. Individual FELs may be configured for different modes of operation, and each may produce high peak and average brightness x-rays with a flexible pulse format, and with pulse durations ranging from sub-femtoseconds to hundreds of femtoseconds. In this paper we describe conceptual design studies and optimizations. We describe recent developments in the design and performance parameters, and progress in R&D activities.

TUPPP071

Design Concepts of a Beam Spreader for a Next Generation Free Electron Laser

kicker, FEL, septum, linac

1765

M. Placidi, P. Emma, J.-Y. Jung, G.C. Pappas, D. Robin, C. Sun, W. Wan
LBNL, Berkeley, California, USA

LBNL is developing design concepts for a multi-beamline soft x-ray FEL array powered by a superconducting linear accelerator, operating with a high bunch repetition rate of approximately one MHz. Electron bunches are distributed from the linac to the array (up to 10) independently configurable FEL beamlines with nominal bunch rates up to 100 kHz in each FEL, and with even pulse spacing. This distribution to the different FELs is made by the beam spreader for which the design has to relative compact while not significantly perturbing the quality of the electron beam and subsequent performance of the FELs. We report on our conceptual design for the spreader. The spreader lattice has two distinct parts, namely the beam take-off section and the FEL fan-out distributions section. Each section is achromatic and isochronous. The effect of coherent synchrotron radiation and micro-bunching has been studied when passing through the spreader and simulations show no significant deterioration in the beam quality.

TUPPP076

Soft Orbit Bumps for Duke Storage Ring VUV FEL Operation

FEL, radiation, wiggler, dipole

1774

S.F. Mikhailov, J.Y. Li, V. Popov, P.W. Wallace, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA

Funding: This work is supported in part by the US DoE grant # DE-FG02-97ER41033.
The Duke FEL and High Intensity Gamma-ray Source (HIGS) facility is operated with an electron beam from 0.24 to 1.2 GeV and a photon beam from 190 to 1060 nm. The current range of the gamma-beam energy is from 1 MeV to about 100 MeV, with the maximum total gamma-flux of more then 10¹⁰ gammas per second around 10 MeV. Production of the high intensity, high energy gamma-beams of 60-100 MeV using UV-VUV mirrors of 240 - 190 nm requires and high energy, high current electron beams of 0.9-1.05 GeV. The radiation damage problem becomes more severe for VUV FEL operation below 190 nm. The radiation from the End-of-Arc (EOA) bending magnets, instead of the radiation from FEL wigglers, is the dominant cause of a rapid degradation of the downstream FEL mirror. In this work, we propose a number of measures to significantly reduce the radiation from these dipole magnets as well as other potential sources of synchrotron radiation toward the FEL mirror. In particular, we describe the development of an orbit bump using designated "soft" orbit correctors. The magnetic field of these correctors is limited to produce a radiation with a critical wavelength close or below the FEL wavelength.

TUPPP079

Design Alternatives for a Free Electron Laser Facility

FEL, linac, undulator, photon

1777

K. Jacobs, J. Bisognano, R.A. Bosch, D. Eisert, M.V. Fisher, M.A. Green, R.G. Keil, K.J. Kleman, J.G. Kulpin, G.C. Rogers, R. Wehlitz
UW-Madison/SRC, Madison, Wisconsin, USA
T. Chiang, T.J. Miller
University of Illinois, Urbana, USA
J.E. Lawler, D. Yavuz
UW-Madison/PD, Madison, Wisconsin, USA
R.A. Legg
JLAB, Newport News, Virginia, USA
R.C. York
FRIB, East Lansing, Michigan, USA

The University of Wisconsin-Madison is continuing design efforts for a vacuum ultraviolet/X-ray Free Electron Laser facility. The design incorporates seeding the FEL to provide fully coherent photon output at energies up to ~1 keV. The focus of the present work is to minimize the cost of the facility while preserving its performance. To achieve this we are exploring variations in the electron beam driver for the FEL, in undulator design, and in the seeding mechanism. Design optimizations and trade-offs between the various technologies and how they affect the FEL scientific program will be presented.

TUPPP082

Optimization of a Terawatt Free Electron Laser

undulator, FEL, radiation, focusing

1780

J. Wu, X. Huang, Y. Jiao, A.U. Mandlekar, T.O. Raubenheimer, S. Spampinati, G. Yu
SLAC, Menlo Park, California, USA
P. Chu
FRIB, East Lansing, Michigan, USA
J. Qiang
LBNL, Berkeley, California, USA

Funding: Work supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC02-76SF00515.
There is great interest in generating a terawatt (TW) hard X-ray free electron laser (FEL) that will enable coherent diffraction imaging of complex molecules like proteins and probe fundamental high-field physics. A feasibility study of producing such pulses was carried out em- ploying a configuration beginning with an SASE amplifier, followed by a "self-seeding" crystal monochromator, and finishing with a long tapered undulator. The undulator tapering profile, the phase advance in the undulator break sections, the quadrupole focusing strength, etc. are parameters to be optimized. A genetic algorithm (GA) is adopted for this multi-dimensional optimization. Concrete examples are given for LCLS/LCLS-II systems.

TUPPP083

Multi-Dimensional Optimization of a Tapered Free Electron Laser

undulator, radiation, FEL, focusing

1783

Y. Jiao, J. Wu
SLAC, Menlo Park, California, USA
Q. Qin
IHEP, Beijing, People's Republic of China

Energy extraction efficiency of a free electron laser (FEL) can be increased when the undulator is tapered. In this paper, we report a multi-dimensional optimizer to maximize the radiation power in a tapered FEL by searching for an optimal taper profile as well as a reasonable variation in electron beam radius. Applications of the proposed multi-dimensional optimization to the terawatt-level, tapered FELs with LCLS-like electron beam parameters are presented, and the proposed optimization scheme is compared with the GINGER’s self-design taper algorithm. At the end, the dependence of the available maximum radiation power on various parameters of the initial electron beam, the initial radiation field and the undulator system is summarized.

TUPPP084

Efficiency Enhancement in a Tapered Free Electron Laser by Varying the Electron Beam Radius

radiation, undulator, FEL, simulation

1786

Y. Jiao, J. Wu
SLAC, Menlo Park, California, USA
Q. Qin
IHEP, Beijing, People's Republic of China

Energy extraction efficiency of a free electron laser (FEL) can be increased when the undulator is tapered. An in-depth understanding of the tapering-related physics is required to explore the full potential of a tapered FEL, not only by tapering the undulator parameters in longitudinal dimension, but also optimizing the transverse effects. Based on the modified 1D FEL model and time-steady numerical simulations, we study the contribution of the variation in electron beam radius and the related transverse effects. Taking a terawatt-level, 120-m tapered FEL as example, we demonstrate that a reasonably varied, instead of a constant, electron beam radius along the undulator helps to improve the optical guiding and thus the radiation output.

TUPPP086

A Synchronized FIR/VUV Light Source at Jefferson Lab

FEL, laser, wiggler, coupling

1789

S.V. Benson, D. Douglas, G. Neil, M.D. Shinn, G.P. Williams
JLAB, Newport News, Virginia, USA

Funding: This work was supported by U.S. DOE Contract No. DE-AC05-84-ER40150, the Air Force Office of Scientific Research, DOE Basic Energy Sciences.
We describe a dual FEL configuration on the UV Demo FEL at Jefferson Lab that would allow simultaneous lasing at THz and UV wavelengths. The THz source would be an FEL oscillator with a short wiggler providing diffraction-limited pulses with pulse energy exceeding 50 microJoules. The THz source would use the exhaust beam from a UVFEL. The coherent harmonics in the VUV from the UVFEL are outcoupled through a hole. The THz source uses a shorter resonator with either hole or edge coupling to provide very high power THz pulses. Simulations indicate excellent spectral brightness in the THz region with over 100 W/cm^-1 output.

TUPPP087

Commissioning of the Fritz Haber Institute Mid-IR FEL

FEL, wiggler, linac, undulator

1792

A.M.M. Todd, H. Bluem, D. Dowell, R. Lange, J.H. Park, J. Rathke, L.M. Young
AES, Princeton, New Jersey, USA
W. Erlebach, S. Gewinner, H. Junkes, A. Liedke, G. Meijer, W. Schöllkopf, W.Q. Zhang, G. von Helden
FHI, Berlin, Germany
S.C. Gottschalk
STI, Washington, USA
K. Jordan
Kevin Jordan PE, Newport News, Virginia, USA
U. Lehnert, P. Michel, W. Seidel
HZDR, Dresden, Germany
R. Wünsch
FZD, Dresden, Germany

The IR and THz FEL at the Fritz Haber Institute (FHI) in Berlin is designed to deliver radiation from 4 to 400 microns. A single-plane-focusing undulator combined with a 5.4-m-long cavity is used is the mid-IR (< 50 micron), while a two-plane-focusing undulator in combination with a 7.2-m-long cavity with a 1-D waveguide for the optical mode is planned for the far-IR. Beam was delivered to the IR beam dump in November 2011. We describe progress since that time in completing the commissioning of the mid-IR beamline and the status of the far-IR beamline design and fabrication.

TUPPP088

Bunch Compressor Design for Potential FEL Operation at eRHIC

FEL, emittance, simulation, linac

1795

Y.C. Jing, Y. Hao, V. Litvinenko
BNL, Upton, Long Island, New York, USA

Electron-Relativistic Heavy Ion Collider (eRHIC) is an upgrade project for the current operation of RHIC. It will provide a high quality electron beam with energy recovery scheme to collide with ion beams. One may think of taking advantage of using this electron beam for FEL operation. Bunch compressor is a crucial component to compress the beam to high peak current for undulators and CSR effect needs to be taken care of to preserve the beam quality. In this paper, authors present a novel bunch compressor design with CSR suppression scheme for the potential FEL operation at eRHIC.

TUPPP090

Studies of Controlled Laser-induced Microbunching Instability at Source Development Laboratory

laser, linac, radiation, space-charge

1798

S. Seletskiy, B. Podobedov, Y. Shen, X. Yang
BNL, Upton, Long Island, New York, USA

We present the studies of controlled microbunching intentionally induced on the beam by the photocathode laser with modulated longitudinal profile. Varying the depth and frequency of longitudinal modulation of the laser pulse allowed us to observe the development of microbunching instability at BNL Source Development Laboratory (SDL) in the controlled environment. That allowed us to benchmark the model of the microbunching gain for the first time. In addition to that, we demonstrated for the first time a constructive work of a so-called longitudinal space charge amplifier, which in case under consideration can be utilized for enhancement of linac-based sources of THz radiation.

TUPPP093

General Results on the Nature of FEL Amplification

FEL, laser, free-electron-laser, wiggler

1804

S.D. Webb
Tech-X, Boulder, Colorado, USA
V. Litvinenko, G. Wang
BNL, Upton, Long Island, New York, USA

Free-electron lasers are increasingly important tools for the material and biological sciences, and although numerical and analytical theory is extensive, a fundamental question about the nature of the FEL growing modes has remained unanswered. In this proceeding, we present results of a topological nature concerning the number of amplifying solutions to the 1-dimensional FEL equations as related to the energy distribution of the electron bunches.

TUPPR001

Spin Tracking Simulation of a Future International Linear Collider

polarization, positron, solenoid, simulation

1807

V.S. Kovalenko, O.S. Adeyemi, L.I. Malysheva, G.A. Moortgat-Pick, A. Ushakov
University of Hamburg, Hamburg, Germany
A.F. Hartin
DESY, Hamburg, Germany
S. Riemann, F. Staufenbiel
DESY Zeuthen, Zeuthen, Germany

Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE
The full physics potential of the International Linear Collider (ILC) is expected to be optimized by using polarized electron and positron beams. To ensure that no significant polarization can be lost during the transport of the electron and positron beams from the source to the interaction region, spin tracking has to be included in all transport elements which can contribute to a potential loss of polarization. The possible sources of depolarization such as the spin rotators and the damping ring have been investigated for the current ILC baseline. The detailed spin tracking simulations and study depolarization was performed by using BMAD and SLICKTRACK computer codes. The new results of our simulations for the ILC are presented.

TUPPR002

Simulations of Positron Polarization in the Undulator-Based Source

undulator, positron, polarization, photon

1810

A. Ushakov, O.S. Adeyemi, V.S. Kovalenko, L.I. Malysheva, G.A. Moortgat-Pick
University of Hamburg, Hamburg, Germany
A.F. Hartin
DESY, Hamburg, Germany
S. Riemann, F. Staufenbiel
DESY Zeuthen, Zeuthen, Germany

Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE
The generation of an intense and highly polarized positron beam is a challenge. The design for the International Linear Collider proposes a positron source based on a helical undulator located at the end of the electron linac. This design allows us to utilize a high energy linear accelerator with both electron and positron beams polarized. The polarization of the positron beam can be enhanced using a photon collimator. The optimization of positron yield and polarization for a wide energy range has been studied for different undulator parameters and collimator designs, taking into account realistic parameters for the capture section. In particular, the effects of misalignment and tolerances are considered.

TUPPR005

Linac Upgrade in Intensity and Emittance for SuperKEKB

linac, emittance, positron, alignment

1819

T. Higo, M. Akemoto, D.A. Arakawa, Y. Arakida, A. Enomoto, S. Fukuda, K. Furukawa, Y. Higashi, H. Honma, N. Iida, M. Ikeda, E. Kadokura, K. Kakihara, T. Kamitani, H. Katagiri, M. Kurashina, S. Matsumoto, T. Matsumoto, H. Matsushita, S. Michizono, K. Mikawa, T. Miura, F. Miyahara, T. Mori, H. Nakajima, K. Nakao, T. Natsui, Y. Ogawa, S. Ohsawa, M. Satoh, T. Shidara, A. Shirakawa, H. Sugimoto, T. Suwada, T. Takatomi, T. Takenaka, Y. Yano, K. Yokoyama, M. Yoshida, L. Zang, X. Zhou
KEK, Ibaraki, Japan
D. Satoh
TIT, Tokyo, Japan

The SuperKEKB is designed to produce 40 times luminosity than that of the KEKB. In order to realize such a high luminosity, the injector linac should provide both electron and positron beams of about 4-5 nC/bunch, which is several times higher than before. In addition, their emittance requirement of the injection beam to the rings is 20 microns, which is a factor of a few tens smaller than before. The intensity and emittance of the electron beam are realized directly by developing the photo RF gun. In contrast, the positron intensity is increased by adopting a higher capture efficiency system with flux concentrator followed by large-aperture accelerators, while its emittance is reduced by a damping ring. For preserving such a low emittance of both beams toward the injection to the rings, the suppression of the emittance growth is crucial. To this end, the alignment of the accelerator components should be a few tens of microns, where we need an improvement by more than a factor 10. The beam-based alignment is definitely needed with better-resolution BPMs. In the present paper are reviewed the overall progress and perspective of the design and the associated component developments.

TUPPR012

Polarized Positron Source with a Compton Multiple Interaction Point Line

positron, laser, simulation, linac

1834

I. Chaikovska, O. Dadoun, P. Lepercq, A. Variola
LAL, Orsay, France
R. Chehab
IN2P3 IPNL, Villeurbanne, France

Positron sources are critical components of the future lepton colliders projects. This is essentially due to the high luminosity required, orders of magnitude higher than existing ones. In addition, polarization of the positron beam rather expands the physics research potential of the machine by increasing the precision of the measurements and enhancing certain types of interactions. In this framework, the Compton sources for polarized positron production are taken into account where the high energy gamma rays are produced by the Compton scattering and subsequently converted in the polarized electron-positron pairs in a target. The Compton multiple IP line is proposed as one of the solutions to increase the number of captured positrons. This allows a significant increase in the emitted gamma ray flux impinging on the target. The gamma ray production with the Compton multiple IPs line is simulated and used for polarized positron generation. Later, a capture section based on an adiabatic matching device followed by a pre-injector linac is simulated to capture and accelerate the positron beam. The results obtained are presented and discussed.

TUPPR023

Final-Focus Optics for the LHeC Electron Beam Line

synchrotron, radiation, quadrupole, synchrotron-radiation

1861

J.L. Abelleira
EPFL, Lausanne, Switzerland
J.L. Abelleira, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland
H. Garcia
UPC, Barcelona, Spain

Funding: Work supported by the European Commission under the FP7 Research Infrastructures project Eu- CARD, grant agreement no. 227579.
One of the options considered for the ECFA-CERN-NuPECC design study for a Large Hadron electron Collider (LHeC)* based on the LHC is adding a recirculating energy-recovery linac tangential to the LHC. First designs of the electron Final Focus System have shown the need to correct the chromatic aberrations. Two designs using different approaches for the chromaticity correction are compared, namely, the local chromaticity correction** and the traditional approach using dedicated sections.
*LHeC Study Group, “A Large Hadron Electron Collider at CERN,” LHeC-Note 2011-001 (2011).
**J. Abelleria et al., "Design Status of LHeC Linac‐Ring Interaction Region," IPAC2011, p. 2796 (2011).

TUPPR040

Update on ILC Positron Source Study at ANL

positron, undulator, polarization, photon

1906

W. Liu, W. Gai
ANL, Argonne, USA

As the new ILC baseline has moved the positron production to the end of electron main linac, both the drive beam energy and beamline layouts have also been changed for the positron source. Now the drive beam energy will be varying from 150GeV to 250GeV and 500GeV (for TeV upgrade) as the colliding center of mass (CM) energy changes. Systematic studies on the performance of positron source under different running scenarios have been done at ANL and the results are presented in this paper.

TUPPR041

Update on ILC Positron Source Start-to-End Simulation

positron, undulator, lattice, linac

1909

W. Liu, W. Gai
ANL, Argonne, USA

As a result of the changes in the new ILC base line, there are many changes in the positron source beamline layouts and thus a new lattice design is required. According to the changes in the ILC baseline, a new lattice design for the ILC positron source has been developed at ANL. In this paper, both the new ILC positron source beamline lattice and the corresponding start to end simulation results are presented.

TUPPR042

On the Polarization Upgrade of ILC Undulator-based Positron Source

polarization, positron, undulator, photon

1912

W. Liu, W. Gai
ANL, Argonne, USA
S. Riemann
DESY, Hamburg, Germany
A. Ushakov
University of Hamburg, Hamburg, Germany

The current nominal polarization for ILC undulator based positron source is 30% without photon collimators. In order to improve the effective luminosity, an upgrade of positron source with higher polarization is required. Some studies on the upgrade options have been done at both DESY and ANL, and the results are presented in this paper.

TUPPR043

New Baseline Design of the ILC RTML System

positron, linac, optics, damping

1915

N. Solyak, V.V. Kapin, A. Vivoli
Fermilab, Batavia, USA
S. Seletskiy
BNL, Upton, Long Island, New York, USA

The new ILC baseline was proposed in 2009 (Strawman baseline - SB2009) to minimize cost of the machine and accommodate many changes made in the design of the accelerator systems. The biggest changes are made in the central area, where BDS, RTML, DR, electron and positron sources are sharing the tunnels. A new layout of the compact DR and re-location of the electron and positron sources to the main tunnel requires a new lattice design for all beamlines in this area. The lattice design was coordinated between accelerator systems and Convention Facility and Siting (CFS) group to eliminate conflicts between beamlines and satisfy construction requirements. In this paper we present a new design of the RTML electron and positron lattices in the central area and other modifications made in the RTML line to accommodate changes to the beamline layouts.

TUPPR050

Design and simulation of Prebuncher for S-band Traveling Linear Accelerator

cavity, coupling, simulation, linac

1930

S. Zarei, F. AbbasiDavani, S. Ahmadiannamini, F. Ghasemi
sbu, Tehran, Iran
H. Shaker
IPM, Tehran, Iran

An S-band Traveling wave linear accelerator with an RF input peak power level up to 2.5 MW, for accelerating 1 mA beam of electron up to 15 MeV, is under construction in Iran. This article presents design procedure of a prebuncher for this accelerator. One standing-cavity type prebuncher is required for bunching electron beam for this accelerator. The intended prebuncher is driven by a coaxial line at 2 kW and operated at the same frequency of the other parts of the accelerator. The magnetic coupling applied has been applied for power coupling to the prebuncher cavity. The optimum dimensions of the prebuncher were obtained by using 2D and 3D electromagnetic codes in the frequency domain. Prebuncher cavity consists of a copper body and coupling loop feed.

TUPPR061

First Magnetic Test of a Superconducting Nb3Sn Wiggler Magnet for CLIC

wiggler, damping, emittance, plasma

1957

D. Schoerling, P. Ferracin, P. Fessia, M. Karppinen, J. Mazet, S. Russenschuck
CERN, Geneva, Switzerland
A.W. Grau
Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
P. Peiffer
KIT, Karlsruhe, Germany

In the Compact Linear Collider (CLIC) the normalized horizontal and vertical emittances of the electron and positron beams must be reduced to 500 nm and 5 nm before the beams enter the 3 TeV linear accelerators. An effective way to accomplish ultra-low emittances are damping rings. Damping rings are storage rings equipped with strong wiggler magnets. In a first approximation damping wigglers are more effective the shorter the period length and the stronger the magnetic field is. Only superconducting wiggler magnets meet the demanding magnetic specifications of the CLIC damping rings. Nb-Ti damping wiggler magnets fulfill the specifications of CLIC but Nb3Sn wiggler magnets would reach higher magnetic fields leading to even better beam properties for CLIC. Moreover, they have at the same time higher thermal and magnetic margins. Therefore, Nb3Sn wiggler magnets are under investigation at CERN despite the challenging manufacturing process. This paper presents first results of Nb3Sn coils and short model tests and outlines the further plans for developing Nb3Sn wiggler magnets at CERN.

TUPPR062

The Conceptual Design of a Vacuum System for the ILC Damping Rings Incorporating Electron Cloud Mitigation Techniques

vacuum, wiggler, photon, damping

1960

J.V. Conway, Y. Li, M.A. Palmer
CLASSE, Ithaca, New York, USA

Funding: Work Supported by DOE Award DE-SC0006505.
We describe the conceptual design of the vacuum system for the damping rings of the International Linear Collider. The design incorporates a range of techniques to suppress the development of the electron cloud (EC) in the positron ring. These techniques include coatings with low secondary electron yield (SEY), grooved chambers, clearing electrodes and antechambers for photoelectron control. The EC mitigation choices are based on the ILC Electron Cloud R&D program, which has been conducted at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) and at other collaborating institutions*. The conceptual designs for vacuum chambers in drifts, dipoles, wigglers and quadrupoles are presented.
* The International Linear Collider: A Technical Progress Report, E. Elsen et al., Eds., pp. 71-81 (2011).

TUPPR063

Investigation into Electron Cloud Effects in the ILC Damping Ring Design

photon, vacuum, wiggler, lattice

1963

J.A. Crittenden, J.V. Conway, G. Dugan, M.A. Palmer, D. L. Rubin
CLASSE, Ithaca, New York, USA
L.E. Boon, K.C. Harkay
ANL, Argonne, USA
M.A. Furman
LBNL, Berkeley, California, USA
S. Guiducci
INFN/LNF, Frascati (Roma), Italy
M.T.F. Pivi, L. Wang
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy DE-SC0006506
We report modeling results for electron cloud buildup in the ILC damping ring lattice design. Updated optics, wiggler magnet, and vacuum chamber designs have recently been developed for the 5-GeV, 3.2-km racetrack layout. An analysis of the synchrotron radiation profile around the ring has been performed, including the effect of photon scattering on the interior of the vacuum chamber. Operational implications of the resulting electron cloud buildup will be discussed.

TUPPR064

Time-resolved Shielded-Pickup Measurements and Modeling of Beam Conditioning Effects on Electron Cloud Buildup at CesrTA

vacuum, photon, simulation, pick-up

1966

J.A. Crittenden, Y. Li, X. Liu, M.A. Palmer, S. Santos, J.P. Sikora
CLASSE, Ithaca, New York, USA
S. Calatroni, G. Rumolo
CERN, Geneva, Switzerland
S. Kato
KEK, Ibaraki, Japan

Funding: Work supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the U.S. Department of Energy DE-FC02-08ER41538.
The Cornell Electron Storage Ring Test Accelerator program includes investigations into electron cloud buildup in vacuum chambers with various coatings. Two 1.1-m-long sections located symmetrically in the east and west arc regions are equipped with BPM-like pickup detectors shielded against the direct beam-induced signal. They detect cloud electrons migrating through an 18-mm-diameter pattern of holes in the top of the chamber. A digitizing oscilloscope is used to record the signals, providing time-resolved information on cloud development. We present new measurements of the effect of beam conditioning on a newly-installed amorphous carbon coated chamber, as well as on a diamond-like carbon coating. The ECLOUD modeling code is used to quantify the sensitivity of these measurements to model parameters, differentiating between photoelectron and secondary-electron production processes.

TUPPR069

Calculation of Wakefields in 17-GHz Beam-Driven Photonic Bandgap Accelerator Structure

dipole, wakefield, simulation, damping

1981

M. Hu, B.J. Munroe, M.A. Shapiro, R.J. Temkin
MIT/PSFC, Cambridge, Massachusetts, USA

We present computer simulations of the wakefields in a six cell Photonic Bandgap (PBG) structure at 17GHz. Using the commercial code CST Particle Studio, the major accelerating mode (TM01) and dipole mode (TM11) are identified. The modes are excited by passing an 18MeV electron beam through the structure. The comparisons of the wakefields in an elliptical-rod PBG structure, round-rod PBG structure, and disc-loaded waveguide structure are carried out to verify experimental results. Various parameters, such as the beam charge and position, are varied to analyze the amplitude and decay time of the wakefields in the three structures. All of the simulation results will guide the design of next generation high gradient accelerator PBG structures.

TUPPR072

Status of ESTB: A Novel Beam Test Facility at SLAC

kicker, wakefield, linac, emittance

1990

M.T.F. Pivi, M.P. Dunning, H. Fieguth, C. Hast, R.H. Iverson, J. Jaros, R.K. Jobe, L. Keller, T.V.M. Maruyama, D.R. Walz, M. Woods
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515
End Station A Test Beam (ESTB) is a test beam line at SLAC in the large End Station A (ESA) experimental hall. It uses a fraction of the bunches of the 14.7 GeV electron beam from the Linac Coherent Light Source (LCLS). ESTB provides a unique test beam for particle and particle astrophysics detector research, accelerator instrumentation and accelerator R&D, development of radiation-hard detectors, and material damage studies. It has exceptionally clean and well-defined secondary electron beams, a huge experimental area and good existing conventional facilities. Recently, a new kicker magnet has been installed to divert 5 Hz of the LCLS low energy beam into the A-line. The full installation will include 4 kicker magnets to allow diversion of high energy beams. A new beam dump and a new Personnel Protection System (PPS) have been built in ESA. In stage II, a secondary hadron target will be able to produce pions up to about 12 GeV/c at 1 particle/pulse. This paper reports the progress on ESTB construction and commissioning.

TUPPR075

Challenges for the Magnet System of LHeC

quadrupole, proton, linac, dipole

1996

S. Russenschuck, B.J. Holzer, G. Kirby, A. Milanese, R. Tomás, D. Tommasini, F. Zimmermann
CERN, Geneva, Switzerland

The main challenges for the normal conducting magnet system are the very compact, low field, and high precision magnets for the ring-ring option and their rapid installation in the crowded LHC tunnel. The superconducting triplet magnets require strong gradients for the protons in close vicinity of a field-free region for the electrons. The field requirements for the ring-ring option allow a number of different magnet designs using the well-proven Nb-Ti superconductor technology and making use of the cable development for the LHC. The separation distance between the electron and proton beams in Q1 requires a half-aperture quadrupole design to limit the overall synchrotron radiation power emitted by the bending of the electron beam. The requirements in terms of aperture and field gradient are more difficult to obtain for the Linac-Ring option. Consequently we present the limitations for the field gradient and septum size achievable with both Nb-Ti and Nb3Sn superconducting technologies.

TUPPR076

The LHeC Project Development Beyond 2012

linac, collider, cavity, dipole

1999

F. Zimmermann, O.S. Brüning
CERN, Geneva, Switzerland
M. Klein
The University of Liverpool, Liverpool, United Kingdom

The LHeC study group is finalizing a Conceptual Design Report for publication early in 2012. This paper discusses the next steps required for developing a Technical Design Report and highlights the R&D developments, test facilities and implementation studies that need to be addressed over the coming years. Particular emphasize will be given to similarities with other ongoing accelerator and detector studies, and to a discussion of possible international collaboration efforts.

TUPPR080

Integration of Detector into Interaction Region at MEIC

ion, dipole, solenoid, optics

2011

V.S. Morozov, R. Ent, P. Nadel-Turonski
JLAB, Newport News, Virginia, USA
C. Hyde
Old Dominion University, Norfolk, Virginia, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The Jefferson Lab's Medium-energy Electron Ion Collider (MEIC) is proposed as a next-generation facility for the study of strong interaction (QCD). Accessing the relevant physics requires a full-acceptance detector with a dedicated small-angle high-resolution detection system capable of covering a wide range of momenta (and charge-to-mass ratios) with respect to the original ion beam. We present a design of such a detection system integrated into the collider's interaction region, in which full acceptance is attained by letting small-angle collision products pass through the nearest elements of the machine final-focusing system for further detection. The proposed design is consistent with the current collider optics and demonstrates an excellent performance in terms of detector acceptance and resolution.
The U.S. Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce this manuscript for U.S. Government purposes.

TUPPR082

MEIC Design Progress

ion, collider, booster, polarization

2014

Y. Zhang, Y.S. Derbenev, D. Douglas, A. Hutton, G.A. Krafft, R. Li, F. Lin, V.S. Morozov, E.W. Nissen, F.C. Pilat, T. Satogata, C. Tennant, B. Terzić, B.C. Yunn
JLAB, Newport News, Virginia, USA
D.P. Barber
DESY, Hamburg, Germany
Y. Filatov
JINR, Dubna, Russia
C. Hyde
Old Dominion University, Norfolk, Virginia, USA
A.M. Kondratenko
Science and Technique Laboratory Zaryad, Novosibirsk, Russia
S.L. Manikonda, P.N. Ostroumov
ANL, Argonne, USA
M.K. Sullivan
SLAC, Menlo Park, California, USA

Funding: Supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177 and No. DE-AC02-06CH11357.
This paper will report the recent progress in the conceptual design of MEIC, a high luminosity medium energy polarized ring-ring electron-ion collider at Jefferson lab. The topics and achievements that will be covered are design of the ion large booster and the ERL-circulator-ring-based electron cooling facility, optimization of chromatic corrections and dynamic aperture studies, schemes and tracking simulations of lepton and ion polarization in the figure-8 collider ring, and the beam-beam and electron cooling simulations. A proposal of a test facility for the MEIC electron cooler will also be discussed.

TUPPR083

Kink Instability Suppression with Stochastic Cooling Pickup and Kicker

ion, feedback, pick-up, kicker

2017

Y. Hao, M. Blaskiewicz, V. Litvinenko, V. Ptitsyn
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The kink instability is one of the major beam dynamics issues of the linac-ring based electron ion collider. This head-tail type instability arises from the oscillation of the electron beam inside the opposing ion beam. It must be suppressed to achieve the desired luminosity. There are various ways to suppress the instability, such as tuning the chromaticity in the ion ring or by a dedicated feedback system of the electron beam position at IP, etc. However, each method has its own limitation. In this paper, we will discuss an alternative opportunity of suppressing the kink instability of the proposed eRHIC at BNL using the existing pickup-kicker system of the stochastic cooling system in RHIC.

TUPPR084

HOM Damping and Multipacting Analysis of the Quarter-wave Crab Cavity

cavity, HOM, damping, simulation

2020

Q. Wu, S.A. Belomestnykh, I. Ben-Zvi
BNL, Upton, Long Island, New York, USA
R. Calaga
CERN, Geneva, Switzerland

The Quarter-Wave Crab Cavity design has been analyzed further to accommodate LHC requirements. The goal for the design is to provide strong deflecting voltage to the proton bunches at the IP, while keeping the effective length as short as possible. We will evaluate the Higher Order Mode damping with two magnetic coupling dampers of 90 degrees apart. In this paper, we also show possible multipacting locations which are simulated by 3D code.

TUPPR088

Baseline Design of the SuperB Factory Injection System

linac, positron, injection, emittance

2032

S. Guiducci, A. Bacci, M.E. Biagini, R. Boni, M. Boscolo, D. Pellegrini, M.A. Preger, P. Raimondi, A.R. Rossi, M. Zobov
INFN/LNF, Frascati (Roma), Italy
M.A. Baylac
LPSC, Grenoble, France
J. Brossard, S. Cavalier, O. Dadoun, T. Demma, P. Lepercq, E. Ngo Mandag, C. Rimbault, A. Variola
LAL, Orsay, France
J.T. Seeman
SLAC, Menlo Park, California, USA
D.N. Shatilov
BINP SB RAS, Novosibirsk, Russia

The injection complex of the SuperB, B-factory project of INFN consists of a polarized electron gun, a positron production system, electron and positron linac sections, a positron damping ring and the transfer lines connecting these systems and the collider main rings. To keep the ultra high luminosity nearly constant, continuous injection of 4 GeV electrons and 7 GeV positrons in both Low Energy Ring (LER) and High Energy Ring (HER) is necessary. In this paper we describe the baseline design and the beam dynamics studies performed to evaluate the system performance.

TUPPR092

Transient Beam Losses in the LHC Injection Kickers from Micron Scale Dust Particles

kicker, beam-losses, vacuum, injection

2044

B. Goddard, P. Adraktas, T. Baer, M.J. Barnes, F. Cerutti, A. Ferrari, N. Garrel, A.H.J. Gerardin, M. Guinchard, A. Lechner, A. Masi, V. Mertens, R. Morón Ballester, S. Redaelli, J.A. Uythoven, V. Vlachoudis, F. Zimmermann
CERN, Geneva, Switzerland

Transient beam losses on a time scale of a few ms have been observed in the LHC injection kickers, occurring mainly shortly after beam injection with a strong correlation in time to the kicker pulsing. The beam losses, which have at times affected LHC availability, are attributed to micron scale ceramic dust particles detached from the alumina beam pipe and accelerated into the beam. The beam related observations are described, together with laboratory measurements of beam pipe contamination and kicker vibration, simulations of electric field in the beam pipe and the basic dynamic model. Energy deposition simulations modelling the beam losses are presented and compared to measurement. Extrapolations to future LHC operation at higher intensities and energies are made, and prospects for mitigation are discussed.

TUPPR095

Update on Kicker Development for the NGLS

kicker, controls, status, impedance

2053

G.C. Pappas, S. De Santis, J.E. Galvin, M.V. Orocz, M. Placidi
LBNL, Berkeley, California, USA

The latest requirements for the Next Generation Light Source (NGLS) beam spreader call for a kicker to deflect a 2.4 GeV electron beam by an angle of 3 mrad over a length of 2 meters. The rise and fall time requirements for the integrated B field are <50 ns, the pulse frequency is up to 100 kHz, and both the inter-pulse and pulse to pulse ripple requirements are <0.01% of full scale. These requirements, along with the basic design of the beam spreader are still evolving, and several magnet types and modulator topologies have been considered. This paper will discuss this evolution as it pertains to the kickers, what the current status is of the R&D effort, and the plan to build a full power prototype system.

WEXA02

Development of Electron Coolers in Novosibirsk

ion, gun, acceleration, proton

2068

V.V. Parkhomchuk
BINP SB RAS, Novosibirsk, Russia
S. Nagaitsev
Fermilab, Batavia, USA

An electron cooling method was proposed by G. Budker aproximately 50 years ago. Since the first demonstrations of strong cooling in 1972, the Novosibirsk Institute of Nuclear Physics has continued to develop this technique for various machines with increasingly higher energy beams. Recent application of the e-cooling method at LEIR appeared as a crucial application for a high luminosity achieved in lead-lead ion beam collisions at LHC. This talk should describe the fundamental mechanism of strong cooling, describe historical progress at the BINP and present recent results achieved at the LHC. New 2MeV cooler for COSY ring under commissioning just now at BINP.

Slides WEXA02 [7.872 MB]

WEYA02

Studies at CesrTA of Electron-Cloud-Induced Beam Dynamics for Future Damping Rings

simulation, emittance, damping, dipole

2081

G. Dugan, M.G. Billing, K.R. Butler, J.A. Crittenden, M.J. Forster, D.L. Kreinick, R.E. Meller, M.A. Palmer, G. Ramirez, M.C. Rendina, N.T. Rider, K.G. Sonnad, H.A. Williams
CLASSE, Ithaca, New York, USA
R.F. Campbell, R. Holtzapple, M. Randazzo
CalPoly, San Luis Obispo, California, USA
J.Y. Chu
CMU, Pittsburgh, Pennsylvania, USA
J.W. Flanagan, K. Ohmi
KEK, Ibaraki, Japan
M.A. Furman, M. Venturini
LBNL, Berkeley, California, USA
M.T.F. Pivi
SLAC, Menlo Park, California, USA

Funding: US National Science Foundation PHY-0734867, PHY-1002467, and PHY-1068662; US Dept. of Energy DE-FC02-08ER41538; and the Japan/US Cooperation Program.
Electron clouds can adversely affect the performance of accelerators, and are of particular concern for the design of future low emittance damping rings. Studies of the impact of electron clouds on the dynamics of bunch trains in CESR have been a major focus of the CESR Test Accelerator program. In this paper, we report measurements of coherent tune shifts, emittance growth, and coherent instabilities carried out using a variety of bunch currents, train configurations, beam energies, and transverse emittances, similar to the design values for the ILC damping rings. We also compare the measurements with simulations which model the effects of electron clouds on beam dynamics, to extract simulation model parameters and to quantify the validity of the simulation codes.

Slides WEYA02 [2.033 MB]

WEXB01

Recent Advances and New Techniques in Visualization of Ultra-short Relativistic Electron Bunches

radiation, laser, FEL, RF-structure

2091

D. Xiang
SLAC, Menlo Park, California, USA

Funding: Work supported by U.S. DOE under Contract No. DE-AC02-76SF00515.
This talk will address advances in the measurement of ultra-short relativistic bunches at femtosecond frontier in high-energy x-ray free-electron lasers (FELs). In general, this presentation will discuss several recently proposed novel techniques (i.e. mapping z exactly to delta * and x **, optical oscilloscope ***, etc.) that are capable of breaking the femtosecond time barrier in measurements of ultrashort bunches. In particular, this presentation will report on the all-optical, time-resolved method to probe beam longitudinal phase space with femtosecond time scale and 10^-5 energy scale resolution ****. The simultaneous measurement of temporal profile and beam slice energy spread after the FEL interaction is also shown to reveal the time-dependent x-ray radiation profile *****.
* Z. Huang et al., PRSTAB 13, 092801.
** D. Xiang, Y. Ding, PRSTAB 13, 094001.
*** G. Andonian et al., PRSTAB 14, 072802.
**** D. Xiang et al., PRSTAB 14, 112801.
***** Y. Ding et al., FEL11.

Slides WEXB01 [6.873 MB]

WEYB01

The SPring-8 Angstrom Compact Free Electron Laser (SACLA)

laser, emittance, undulator, FEL

2106

H. Tanaka
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

Commissioning of the world's first compact X-ray FEL facility named SPring-8 Angstrom Compact free electron LAser (SACLA) began in the Spring of 2011 and soon demonstrated lasing at a wavelength of 0.12nm. In the autumn of 2011 laser intensity reached sub mJ/pulse in the wavelengths ranging from 0.1 to 0.3 nm. The laser power saturation was also achieved at around or longer than 0.1 nm. The official user operation will start from March 2012. This presentation will cover innovative design aspects of the SACLA construction project, events leading to key milestones in the commissioning process, a review of the present status and perspectives on future upgrades.

Slides WEYB01 [13.170 MB]

WEYB03

High Average Power UV Free Electron Laser Experiments at JLAB

FEL, wiggler, cavity, linac

2111

D. Douglas, S.V. Benson, P. Evtushenko, J.G. Gubeli, C. Hernandez-Garcia, R.A. Legg, G. Neil, T. Powers, M.D. Shinn, C. Tennant, G.P. Williams
JLAB, Newport News, Virginia, USA

Funding: Authored by JSA LLC under US DOE Contract #DE-AC05-06OR23177. The U.S. Gov. retains non-exclusive, paid-up, irrevocable, world-wide license to publish/reproduce this manuscript for U.S. Gov. purposes.
Having produced 14 kW of average power at ~2 microns, JLAB has shifted its focus to the ultraviolet portion of the spectrum. This presentation will describe the JLab UV Demo FEL, present specifics of its driver ERL, and discuss the latest experimental results from FEL experiments and machine operations.

Slides WEYB03 [2.863 MB]

WEOAA02

Inorganic Scintillators for Particle Beam Profile Diagnostics of Highly Brilliant and Highly Energetic Electron Beams

diagnostics, radiation, simulation, monitoring

2119

G. Kube, C. Behrens, C. Gerth, B. Schmidt
DESY, Hamburg, Germany
W. Lauth
IKP, Mainz, Germany
M. Yan
Uni HH, Hamburg, Germany

Transverse beam profile diagnostics in electron linacs are widely based on optical transition radiation (OTR) as standard technique. The experience from modern linac based light sources shows that OTR diagnostics might fail because of coherence effects in the OTR emission process. As consequence, for the new 4th generation light sources as the European X-FEL, new reliable tools for transverse beam profile measurements are required. Scintillating screens are widely used for particle beam diagnostics, especially in transverse profile measurements at hadron machines and low energy electron machines where the intensity of OTR is rather low. Their usage may serve as an alternative way to overcome limitations in OTR based beam diagnostics imposed by the influence of coherent emission. However, there is only little information about scintillator properties for applications with high energetic electrons. Therefore, test experiments have been performed at the Mainz Microtron (MAMI) in order to study the screen applicability. The status of these experiments will be presented and the results will be discussed in view of scintillator material properties and observation geometry.

Slides WEOAA02 [1.648 MB]

WEOAA03

Development of the Beam Halo Monitor in the J-PARC 3-GeV RCS

extraction, injection, beam-losses, gun

2122

M. Yoshimoto, N. Hayashi, H. Hotchi, M. Kinsho, S.I. Meigo, K. Okabe, P.K. Saha, K. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

Transverse beam halo is one of the most important beam parameters due to limit the performance of the high intensity beam accelerator. Therefore the transverse beam halo measurement is required to increase the beam power of the J-PARC 3-GeV RCS. Transverse halo monitors, which are horizontal and vertical scanning aluminum plates type, has been installed in the extraction beam line. But the residual secondary electrons hindered the beam halo diagnostic. Thus we develop the new beam halo monitor with vibrating wire monitor.

Slides WEOAA03 [6.701 MB]

WEOBA01

Construction Progress of the RHIC Electron Lenses

solenoid, gun, proton, dipole

2125

W. Fischer, Z. Altinbas, M. Anerella, E.N. Beebe, M. Blaskiewicz, D. Bruno, W.C. Dawson, D.M. Gassner, X. Gu, R.C. Gupta, K. Hamdi, J. Hock, L.T. Hoff, A.K. Jain, R.F. Lambiase, Y. Luo, M. Mapes, A. Marone, T.A. Miller, M.G. Minty, C. Montag, M. Okamura, A.I. Pikin, S.R. Plate, D. Raparia, Y. Tan, C. Theisen, P. Thieberger, J.E. Tuozzolo, P. Wanderer, S.M. White, W. Zhang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy.
In polarized proton operation, the RHIC performance is limited by the head-on beam-beam effect. To overcome these limitations two electron lenses are under construction. We give an overview of the progress over the last year. Guns, collectors and the warm electron beam transport solenoids with their associated power supplies have been constructed. The superconducting solenoids that guide the electron beam during the interaction with the proton beam are near completion. A test stand has been set up to verify the performance of gun, collector and some of the instrumentation. The RHIC infrastructure is being prepared for installation, and simulations continue to optimize the performance.

Slides WEOBA01 [7.672 MB]

WEOBA03

Beam Tests of a High Pressure Gas-Filled Cavity for a Muon Collider

cavity, ion, pick-up, collider

2131

T.A. Schwarz, M.A. Leonova, A. Moretti, M. Popovic, A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, USA
M. Chung
Handong Global University, Pohang, Republic of Korea
B.T. Freemire, P.M. Hanlet, Y. Torun
IIT, Chicago, Illinois, USA
R.P. Johnson
Muons, Inc, Batavia, USA

Funding: US DOE under contract DE-AC02-07CH11359.
One of the greatest challenges in constructing a Muon Collider is cooling the hot muons into a focused beam after their production. Because the beam must be cooled quickly before the muons decay, compact cooling designs require high gradient cavities inside strong magnetic fields. Unfortunately, due to focused field emission, an external magnetic field degrades the performance of the cavity below what is required for a muon collider. High-pressure gas inside the cavity has been proposed to both mitigate this effect, as well as serve as an absorber for transversely cooling the muon beam. A prototype of a high pressure gas-filled cavity is currently being studied at the Muon Test Area at Fermilab. The experimental setup as well as several measurements of the physics and performance of the apparatus while operating in a 400-MeV proton beam will be discussed.

Slides WEOBA03 [6.912 MB]

WEOAB01

New Results from the EMMA Experiment

acceleration, injection, resonance, betatron

2134

B.D. Muratori, J.K. Jones
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
C.S. Edmonds, K.M. Hock, M.G. Ibison, I.W. Kirkman
The University of Liverpool, Liverpool, United Kingdom
J.M. Garland, H.L. Owen
UMAN, Manchester, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

EMMA (Electron Model for Many Applications) is a prototype non-scaling electron FFAG hosted at Daresbury Laboratory. After demonstration of acceleration in the serpentine channel in April 2011, the beam study with EMMA continues to explore the large transverse and longitudinal acceptance and effects of integer tune crossing with slower rate on the betatron amplitude. Together with a comparison of detailed models based on measured field maps and the experimental mapping of the machine by relating the initial and final phase space coordinates. These recent results together with more practical improvements such as injection orbit matching with real-time monitoring of the coordinates in the transverse phase space will be reported in this paper.

Slides WEOAB01 [2.120 MB]

WEOAB02

Photocathode R&D at Cornell University

vacuum, emittance, cathode, gun

2137

L. Cultrera, I.V. Bazarov, J.V. Conway, B.M. Dunham, Y. Hwang, Y. Li, X. Liu, R. Merluzzi, T.P. Moore, K.W. Smolenski
CLASSE, Ithaca, New York, USA
S.S. Karkare, J.M. Maxson, W.J. Schaff
Cornell University, Ithaca, New York, USA

Funding: This work has been supported by NSF DMR-0807731 and by DOE DE-SC0003965.
A wide R&D program is pursued at Cornell University aimed at preparation and characterization of high efficiency photocathodes for the Energy Recovery Linac photoinjector. The currently investigated photoemitters include both positive and negative electron affinity materials such as respectively bi-alkali antimonide and III-V semiconductors activated with Cs and either O or F. Analysis techniques as Scanning Auger Spectroscopy, Low Energy Electron Diffraction, Reflected High Energy Electron Diffraction and work function measurements are used to characterize the surfaces properties of the specimens. Spectral response, photoemission uniformity, electron energy distributions are used to characterize the quality of the photoelectron beam and to relate it to the measured surface properties.

Slides WEOAB02 [6.934 MB]

WEOBB01

Measurement of the Local Energy Spread of Electron Beam at SDUV-FEL

laser, FEL, bunching, radiation

2143

C. Feng, J.H. Chen, H.X. Deng, T. Lan, B. Liu, D. Wang, X. Wang, M. Zhang, T. Zhang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

The slice energy spread of electron beam is a very important parameter for high gain free electron lasers (FELs) especially the seeded FELs. Because of its extremely small value, highly accurate measurement of the slice energy spread is rather challenging. In this paper, we propose a novel method to accurately measure the slice energy spread based on the coherent harmonic generation (CHG) scheme. This method has been demonstrated on the Shanghai deep ultraviolent FEL (SDUV-FEL), and the results show that the slice energy spread is about only 1.2keV at the exit of the 136MeV linac when the bunch compressor is off, and this value change to about 2.6keV when the bunch compressor is on.
* Chao Feng, et al, Phys. Rev. ST Accel. Beams 14, 090701 (2011)

Slides WEOBB01 [3.309 MB]

WEOBB02

Refraction Contrast Imaging via Laser-Compton X-Ray Using Optical Storage Cavity

laser, cavity, photon, linac

2146

K. Sakaue, T. Aoki, M. Washio
RISE, Tokyo, Japan
M.K. Fukuda, Y. Honda, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

We have been developing a pulsed-laser storage technique in a super-cavity for a compact x-ray sources. The pulsed-laser super-cavity enables to make high peak power and small waist laser at the collision point with the electron beam. Recently, using 357 MHz mode-locked Nd:VAN laser pulses which stacked in a super-cavity scattered off a multi-bunch electron beam, we obtained a multi-pulse x-rays through the laser-Compton scattering. Then, we performed a X-ray imaging via laser-Compton X-ray. The images have edge enhancement by refraction contrast because the X-ray source spot size was small enough. This is one of the evidences that laser-Compton X-ray is high quality. Our laser-Compton experimental setup, the results of X-ray imaging and future prospective will be presented at the conference.

Slides WEOBB02 [4.393 MB]

WEOBB03

Computation of the Wigner Distribution for Undulator Radiation

radiation, undulator, synchrotron, brightness

2149

I.V. Bazarov, A.D. Gasbarro
CLASSE, Ithaca, New York, USA

In the effort to optimize brightness in synchrotron radiation sources, questions arise as to the most desirable electron beam parameters given a particular insertion device. With a detailed understanding of the distribution of emitted photons, the electron beam profile can be effectively matched. We have developed tools which, by way of the Wigner distribution, compute the phase space of photons radiated by an electron bunch. An explanation is provided of the workings of the code itself with mention of important algorithms that have been implemented. We demonstrate via numerical examples the Wigner distributions of the undulator radiation. In particular, it is shown that the phase space of light differs appreciably from the Gaussian distribution assumed in many analytical expressions and, therefore, the more thorough approaches should be used for computation of related quantities.

Slides WEOBB03 [2.555 MB]

WEIC04

Functional Materials Development using Accelerator-based Light Sources: Current Capabilities and Future Prospects

FEL, controls, synchrotron, radiation

2156

W.R. Flavell
UMAN, Manchester, United Kingdom

Funding: UK Engineering and Physical Sciences Research Council (EPSRC), UK Science and Technology Facilities Council (STFC)
The development of accelerator-based light sources has allowed access to photons of very high brightness and wide tunability. These properties of synchrotron radiation (SR) mean that it can be used to resolve questions that can be answered in no other way, enabling unique contributions to the development of functional materials. Increasingly, these benefits have become essential to material evaluation in manufacturing – ranging from intelligent catalysts for automotive emissions control* to next generation photovoltaics**. Bright, tunable X-rays have been a boon to nanotechnology*** in particular, with its requirement for atom-by-atom understanding – and this benefit is enhanced by the microfabrication capabilities of X-ray lithography in LIGA-based techniques. The result is unique potential for nanoscale device manufacture. The application of bright tunable X-rays to the development of nanostructures for a range of industrial applications is illustrated, and the prospects for exploitation of the ultra-high brightness and femtosecond time structure of FEL radiation are discussed.
* H Tanaka et al., Ang. Chemie Int. Ed. 45, 5998 (2006)
** S J O Hardman et al., Phys Chem Chem Phys 13, 20275 (2011)
*** S Biswas et al., Small (2012) DOI: 10.10⁰²/smll201102100

Slides WEIC04 [11.723 MB]

WEEPPB001

Progress Toward a High-Transformer-Ratio Dielectric Wakefield Experiment at FLASH

wakefield, laser, acceleration, simulation

2166

F. Lemery, D. Mihalcea, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
J. Osterhoff
MPQ, Garching, Munich, Germany
C.A.J. Palmer
DESY, Hamburg, Germany
P. Stoltz
Tech-X, Boulder, Colorado, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
Dielectric wakefield accelerators offer many advantages over conventional RF accelerators such as higher acceleration gradients and cost effectiveness. In this paper we describe our experimental plans to demonstrate enhanced transformer ratios with drive and witness bunches. The experiment, will be performed at the Free-electron LASer in Hamburg (FLASH) and utilizes unique pulse shaping capabilities using the dual-frequency superconducting linac to produce high transformer ratios (>2). The beam-driven acceleration mechanism will be based on a cylindrical-symmetric dielectric-lined waveguide (DLW). The experimental setup is described, and start-to-end numerical simulations of the experiment will be presented.

WEEPPB002

Plasma Acceleration Experiment at SPARC_LAB with External Injection

plasma, laser, acceleration, injection

2169

L. Serafini, A. Bacci
Istituto Nazionale di Fisica Nucleare, Milano, Italy
M. Bellaveglia, M. Castellano, E. Chiadroni, G. Di Pirro, M. Ferrario, A. Gallo, G. Gatti, A.R. Rossi, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
C. Maroli, V. Petrillo
Universita' degli Studi di Milano, Milano, Italy
A. Mostacci
URLS, Rome, Italy
P. Tomassini
Università degli Studi di Milano, Milano, Italy

At the SPARC-LAB facility of INFN-LNF we are installing two transport lines for ultra-short electron bunches and an ultra-intense laser pulses, generated by the SPARC photo-injector and by the FLAME laser in a synchronized fashion at the tens of fs level, to co-propagate inside a hydrogen filled glass capillary, in order to perform acceleration of the electron bunch by a plasma wave driven by the laser pulse. The main aim of this experiment is to demonstrate that a high brightness electron beam can be accelerated by a plasma wave without any significant degradation of its quality. A 10 pC electron bunch, 10 fs long is produced by SPARC and transported to injection into the capillary, which is 100 micron wide, at a gas density around 5*10¹⁷ ne/cm³ . The laser pulse, 25 fs long, focused down to 30 microns into the capillary is injected ahead of the bunch, drives a weakly non-linear plasma wave with wavelength of about 120 microns. A proper phasing of the two pulses allows acceleration of electrons from the injection energy of 150 MeV up to about 1 GeV for a 10 cm long capillary. Installation of the beam lines is foreseen by the end of 2012 and first tests starting in mid 2013.

WEEPPB004

Status of the APEX Project at LBNL

gun, cathode, cavity, laser

2173

F. Sannibale, B.J. Bailey, K.M. Baptiste, J.M. Byrd, C.W. Cork, J.N. Corlett, S. De Santis, L.R. Doolittle, J.A. Doyle, P. Emma, J. Feng, D. Filippetto, G. Huang, H. Huang, T.D. Kramasz, S. Kwiatkowski, W.E. Norum, H.A. Padmore, C. F. Papadopoulos, G.C. Pappas, G.J. Portmann, J. Qiang, D.G. Quintas, J.W. Staples, T. Vecchione, M. Venturini, M. Vinco, W. Wan, R.P. Wells, M.S. Zolotorev, F.A. Zucca
LBNL, Berkeley, California, USA
M. J. Messerly, M.A. Prantil
LLNL, Livermore, California, USA
C.M. Pogue
NPS, Monterey, California, USA

Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
The Advanced Photo-injector Experiment (APEX) at the Lawrence Berkeley National Laboratory is focused on the development of a high-brightness high-repetition rate (MHz-class) electron injector for X-ray FEL applications. The injector is based on a new concept gun, utilizing a normal conducting 186 MHz RF cavity operating in cw mode in conjunction with high quantum efficiency photocathodes capable of delivering the required repetition rates with available laser technology. The APEX activities are staged in 3 main phases. In Phases 0 and I, the gun will be tested at its nominal energy of 750 keV and several different photocathodes are tested at full repetition rate. In Phase II, a pulsed linac will be added for accelerating the beam at several tens of MeV to reduce space charge effects and measure the high-brightness performance of the gun when integrated in an injector scheme. At Phase II energies, the radiation shielding configuration of APEX limits the repetition rate to a maximum of several Hz. Phase 0 is under commissioning, Phase I under installation, and initial activities for Phase II are underway. This paper presents an update on the status of these activities.

WEEPPB015

Temperature Dependence of the Superheating Field: DC and RF Critical Fields

cavity, niobium, superconductivity, SRF

2197

N.R.A. Valles, M. Liepe
CLASSE, Ithaca, New York, USA

The superheating field is a metastable state at which the Meissner state persists at fields higher than would be predicted from steady-state energy considerations. Previous work demonstrated that a phenomenological approach based on the RF superheating field scaling near the critical temperature is also consistent with low temperature results. This work expands upon the RF results by measuring the DC superheating field, and comparing it to RF results and theoretical predictions.

WEPPC021

Development of Superconducting Radio Frequency Cavities at SINAP

cavity, niobium, superconducting-cavity, HOM

2248

J.F. Liu, H.T. Hou, C.W. Lu, C. Luo, Z.Y. Ma, D.Q. Mao, J. Shi, Zh.G. Zhang, S.J. Zhao, X. Zheng
SINAP, Shanghai, People's Republic of China
Z.Q. Feng, Z. Li, J.F. Liu, Y.L. Wei, K. Xu, Y.B. Zhao
Shanghai KEY Laboratory of Cryogenics & Superconducting RF Technology, Shanghai, People's Republic of China
H. Yu
Graduate School of the Chinese Academy of Sciences, Beijing, People's Republic of China

This paper presents the development of superconducting radio frequency cavities at Shanghai Institute of Applied Physics (SINAP) mainly focused on the 500MHz band. Firstly, Two KEKB type 500MHz single cell niobium cavities have been fabricated and one of them has been vertical tested successfully in 2010. The highest accelerating gradient of the fabricated cavity higher than 10MV/m was obtained while the quality factor was better than 4·10⁸ at 4.2K. Secondly, a new type of 500MHz single cell cavity has been designed which adopts the fluted beam pipe for higher order modes propagation and a coaxial type high power input coupler. Thirdly, a 500MHz 5-cell superconducting cavity with large aperture, enlarged beam pipe for HOM propagation and high r/Q value has been optimized which can be a candidate cavity for high current FEL and ERL.

WEPPC033

RF and Surface Properties of Bulk Niobium and Niobium Film Samples

niobium, quadrupole, collider, photon

2278

T. Junginger, W. Weingarten
CERN, Geneva, Switzerland
R. Seviour
University of Huddersfield, Huddersfield, United Kingdom
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: Work supported by the German Doctoral Students program of the Federal Ministry of Education and Research (BMBF)
The surface resistance Rs of superconducting cavities can be obtained from the unloaded quality factor Q0. Since RS varies strongly over the cavity surface its value must be interpreted as averaged over the whole cavity surface. A more convenient way to investigate the surface resistance of superconducting materials is therefore to examine small samples, because they can be manufactured cheaply, duplicated easily and used for further surface analyses. At CERN a compact Quadrupole Resonator has been developed for the RF characterization of superconducting samples at different frequencies. In this contribution, results from measurements on bulk niobium and niobium film on copper samples are presented. Different models accounting for the field depended surface resistance are being confronted by the experimental results. The RF results are being correlated to surface analyses measurements carried out on the same samples.

WEPPC034

LA³NET - An International Network on Laser Applications at Accelerators

laser, ion, acceleration, diagnostics

2281

C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom

Funding: This project is funded by the European Union under contract PITN-GA-2011-289191.
Lasers have become increasingly important for the successful operation and continuous optimization of particle accelerators: Laser-based particle sources are well suited for delivering the highest quality ion and electron beams, laser acceleration has demonstrated unprecedented accelerating gradients and might be an alternative for conventional particle accelerators in the future, and without laser-based beam diagnostics it would not be possible to unravel the characteristics of many complex particle beams. The LA³NET project will bring together research centers, universities, and industry partners to jointly train 17 early stage researchers. In addition, the consortium will also organize a number of international training events, such as schools, topical workshops and conferences. This contribution gives examples from the network's broad research program and summarizes planned training events.

WEPPC042

Low Impedance Bellows for High-current Beam Operations

cryomodule, impedance, wakefield, SRF

2303

G. Wu, K.-J. Kim, A. Nassiri, G.J. Waldschmidt, Y. Yang
ANL, Argonne, USA
J.J. Feingold, J.D. Mammosser, R.A. Rimmer, H. Wang
JLAB, Newport News, Virginia, USA
J. Jang, S.H. Kim
POSTECH, Pohang, Kyungbuk, Republic of Korea

Funding: Work Supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract No. DE-AC02-06CH11357
In particle accelerators, bellows are commonly used to connect beamline components. Such bellows are traditionally shielded to lower the beam impedance. Excessive beam impedance can cause overheating in the bellows, especially in high beam current operation. For an SRF-based accelerator, the bellows must also be particulate free. Many designs of shielded bellows incorporate rf slides or fingers that prevent convolutions from being exposed to wakefields. Unfortunately these mechanical structures tend to generate particulates that, if left in the SRF accelerator, can migrate into superconducting cavities, the accelerator's critical components. In this paper, we describe a prototype unshielded bellows that has low beam impedance and no risk of particulate generation.

WEPPC051

Multipactor Simulation in SC Elliptical Shape Cavities

cavity, simulation, multipactoring, accelerating-gradient

2327

S. Kazakov, I.V. Gonin, V.P. Yakovlev
Fermilab, Batavia, USA

Typically multipactor exists near equator region in elliptical shape superconductive cavities. If the multipactor power zone dose not coincide with operating power, it is often the cavity has to pass through it before it reaches operating level of field. Results of multipactor simulations for several shapes of elliptical cavity are presented. New shape, which significantly suppresses multipactor, is found.

WEPPC084

Development of a Superconducting 500 MHz Multi-Spoke Cavity for Electron Linacs

cavity, cryomodule, SRF, niobium

2408

D. Gorelov, C.H. Boulware, T.L. Grimm
Niowave, Inc., Lansing, Michigan, USA
S.U. De Silva, J.R. Delayen, C.S. Hopper, R.G. Olave
ODU, Norfolk, Virginia, USA

Funding: This work is supported by the US Department of Energy SBIR/STTR program through the Office of Nuclear Physics.
Multi-spoke cavities are well-known options for acceleration of heavy and light ions. A recently developed multi-spoke cavity for β=1 presents an attractive opportunity to use this cavity type for electron accelerators. One of the main attractive features of this cavity type is its compactness for relatively low frequency. A simplified design at 500 MHz allowed building of a multi-spoke cavity and cryomodule in a 2-year time frame with confidence and development of effective manufacturing techniques. It also constitutes an important step in proving the usefulness of this kind of cavity design for new applications in the electron machines. Niowave is now in a position to build on the success of this cavity to help advance the design of superconducting electron accelerators. Accelerating voltage of more then 4.3 MV in a single cavity at 4.5 K is expected with peak electric field of less then 21.7 MV/m, and peak magnetic field of less then 80 mT. The paper discusses the fabrication challenges of the complete cavity and the cryomodule, as well as room temperature and cryogenic test results.

WEPPC096

Exploring the Effect of AL2O3 ALD Coating on a High Gradient ILC Single-Cell Cavity

cavity, niobium, SRF, site

2441

G.V. Eremeev, A-M. Valente-Feliciano, A.T. Wu
JLAB, Newport News, Virginia, USA
D. Gu
ODU, Norfolk, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Encouraged by work at Argonne National Lab, we investigated atomic layer deposition technique for high gradient superconducting RF cavities at JLab with an ALD coating system of Old Dominion University located on the JLab site. The goal of this study was to look into the possibility of coating a dielectric layer on top of RF niobium surface at a lower temperature of 120 C as compared to ANL coatings at 200 C in order to preserve niobium pentooxide on niobium surface. The initial coatings showed complete, but non-uniform coatings of the surface with several areas exhibiting discoloration, which was probably due to the temperature variation during coatings. The initial coating showed a high RF losses, which were improved after discolored areas on the beam tubes were removed with HF rinse of the beam tubes only. The best result was 2·10⁹ low field Q0 and Eacc = 18 MV/m limited by available power.

WEPPC100

Design of Electron and Ion Crabbing Cavities for an Electron-Ion Collider

cavity, HOM, ion, damping

2447

A. Castilla, J.R. Delayen, G.A. Krafft
ODU, Norfolk, Virginia, USA
A. Castilla
JLAB, Newport News, Virginia, USA

Beyond the 12 GeV upgrade at the Jefferson Lab a Medium Energy Electron-Ion Collider (MEIC) has been considered. In order to achieve the desired high luminosities at the Interaction Points (IP), the use of crabbing cavities is under study. In this work, we will present to-date designs of superconducting cavities, considered for crabbing both ion and electron bunches. A discussion of properties such as peak surface fields and higher-order mode separation will be presented.

WEPPC101

Characteristics and Fabrication of a 499 MHz Superconducting Deflecting Cavity for the Jefferson Lab 12 GeV Upgrade

cavity, vacuum, target, niobium

2450

H. Park, S.U. De Silva
JLAB, Newport News, Virginia, USA
J.R. Delayen
ODU, Norfolk, Virginia, USA

A 499 MHz parallel bar superconducting deflecting cavity has been designed and optimized for a possible implementation at the Jefferson Lab 12 GeV upgrade. This paper will present the analysis of the mechanical characteristics of the cavity (pressure sensitivity and tunability) and will detail the fabrication process. The unique geometry of the cavity–which is currently being fabricated at Jefferson Lab–and its required mechanical strength present interesting manufacturing challenges.

WEPPC103

Development of Spoke Cavities for High-velocity Applications

cavity, higher-order-mode, multipole, impedance

2456

C.S. Hopper, J.R. Delayen
ODU, Norfolk, Virginia, USA
R.G. Olave
Old Dominion University, Norfolk, Virginia, USA

In response to recent interest in alternatives to elliptical cavities for low-frequency, high-velocity applications we have initiated a program for the development of multi-spoke superconducting cavities. We have completed the electromagnetic design for two-spoke cavities operating at 352 and 325 MHz and a design velocity of β = 0.82 and β = 1. We present the results of the optimization, higher order mode (HOM) analysis, multipacting analysis, and an initial multipole expansion study of the fundamental accelerating mode.

WEPPC105

Study of Etching Rate Uniformity in SRF Cavities

cavity, plasma, SRF, coupling

2462

J. Upadhyay, S. Popović, L. Vušković
ODU, Norfolk, Virginia, USA
H.L. Phillips, A-M. Valente-Feliciano
JLAB, Newport News, Virginia, USA

Plasma based surface modification is a promising alternative to wet etching of superconducting radio frequency (SRF) cavities. The crucial aspect of the technology development is dependence of the etching rate and surface roughness on the frequency of the power supply, pressure, power level, driven electrode shape and chlorine concentration in gas mixture during plasma processing. To optimize the plasma parameters, we are using a single cell cavity with 20 sample holders symmetrically distributed over the cell. These holders are used as diagnostic ports for the measurement of the plasma parameters and as holders for the samples to be etched. The plasma properties are highly correlated with the shape of the driven electrode and the percentage of chlorine concentration in Argon/chlorine gas mixtures. The effect of the plasma parameters and chlorine gas concentration are investigated at RF (100 MHz) and microwave (2.45 GHz) frequencies.

WEPPC109

Superconducting RF Systems for eRHIC

SRF, linac, cavity, hadron

2474

S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, H. Hahn, D. Kayran, G.J. Mahler, G.T. McIntyre, C. Pai, I. Pinayev, V. Ptitsyn, J. Skaritka, R. Than, J.E. Tuozzolo, Q. Wu, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA
S.A. Belomestnykh, V. Litvinenko, T. Xin
Stony Brook University, Stony Brook, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Future electron-hadron collider eRHIC will consist of a six-pass 30-GeV electron ERL and one of RHIC storage rings operating with energy up to 250 GeV. The collider design extensively utilizes superconducting RF (SRF) technology in both electron and hadron parts. This paper describes various SRF systems, their requirements and parameters.

WEPPC110

3D Simulations of Multipacting in the 56 MHz SRF Cavity

simulation, cavity, HOM, higher-order-mode

2477

Q. Wu, S.A. Belomestnykh
BNL, Upton, Long Island, New York, USA
L. Ge, C. Ko, Z. Li, C.-K. Ng, L. Xiao
SLAC, Menlo Park, California, USA

Funding: This work was supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
The 56 MHz SRF Quarter-Wave Resonator (QWR) is designed for RHIC as a storage cavity to improve the collider performance. 2D multipacting simulation has been done for the cavity alone. Ripples were added to the outer body of the cavity for multipacting suppression based on the simulation findings. During operation, there will be four higher order mode (HOM) couplers and a fundamental power coupler (FPC) inserted through the end ports of the cavity and a fundamental mode damper (FD) inserted through a special port on the outer body. All of these components will be exposed to high RF fields. In this presentation we compare 2D and 3D codes simulation results for multipacting in the cavity. We also report 3D simulation results for multipacting simulation at the couplers.

WEPPC112

Development of a Fundamental Power Coupler for High-Current Superconducting RF Cavity

simulation, cavity, collider, linac

2483

P. Jain
Stony Brook University, Stony Brook, USA
S.A. Belomestnykh, I. Ben-Zvi, W. Xu
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE and by the DOE grant DE-SC0002496 to Stony Brook University.
Brookhaven National Laboratory has undertaken a project to design a five-cell superconducting 703.75 MHz RF cavity for the Energy Recovery Linac (ERL) and the planned RHIC electron cooler. The earlier developed cavity, viz., the BNL1 is fed by a klystron using a co-axial Fundamental Power Coupler (FPC), which delivers 50 kW of cw RF power to the cavity. During the cavity operation, it has been observed that a 5 K cooling line intercept in the FPC introduces undesirable microphonics. A modification in the existing FPC has been planned to determine the feasibility of getting rid of the 5 K cooling line. The modified coupler will be incorporated in the newly designed, under construction BNL3 cavity. In order to accommodate this modification, peak microphonics of 12 Hz and 20 kW of cw RF power will be considered. This paper describes the design of the new FPC starting from the analysis of thermal profile along its length from first principles.

WEPPD013

Status of the Vacuum System in J-PARC RCS

vacuum, ion, proton, site

2522

J. Kamiya, Y. Hikichi, M. Kinsho, M. Nishikawa, N. Ogiwara, T. Yanagibashi
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

In the vacuum system of J-PARC Rapid cycling synchrotron (RCS), we use beam pipes and bellows whose materials are vacuum fired at 700~850 oC in order to eliminate atoms in their bulk who are origin of outgassing. Until now, beam power has been increased up to 300 kW. Pressure in synchrotron beam line increased when the high power beam was accelerated. However, increment of pressure has reduced during the continuous beam operation. It is because the molecules, which adsorb on surface of the wall of the vacuum chambers, desorb by an ion bombardment and a heat generation due to an eddy current. Because the atoms in the bulk is eliminated, desorption of the molecules, which adsorb on the surface, means the reduction of the outgassing from the wall. In this presentation, we will report the past situation of the vacuum system during the beam operation. In addition, we also show the status after the Great East Japan Earthquake.

WEPPD018

LHC Beam Vacuum During 2011 Machine Operation

vacuum, kicker, injection, proton

2534

G. Lanza, V. Baglin, G. Bregliozzi, J.M. Jimenez
CERN, Geneva, Switzerland

During the year 2011 the LHC operated for 682 fills, meaning 247 days and 2 hours of stable beam in total. From 368 bunches per beam at 150 ns bunch spacing circulating in the ring in December 2010, the 2011 proton physic ended with 1380 bunches per beam circulating with 50 ns bunch spacing. The machine performances increased in parallel with the vacuum improvement thanks to a well performed scrubbing run in April 2011 and a continuous conditioning of the beam pipes while the machine was running. The 2011 LHC operation ended with one month of ions physic runs. During the machine operation various phenomena of beam - vacuum interaction were detected, analyzed and solved. This paper describes the pressure behavior along the machine layout and mainly in specific components position like TDI and MKI. The “pressure spike” phenomena near the experiment CMS and in some Dipole 1 (D1) regions are discussed. Finally, results obtained during the 25 ns machine developments are presented.

WEPPD020

Vacuum System for TPS Booster

vacuum, booster, lattice, ion

2540

C.M. Cheng, C.K. Chan, C.L. Chen, J.-R. Chen, G.-Y. Hsiung, S-N. Hsu, H.P. Hsueh
NSRRC, Hsinchu, Taiwan

The TPS booster is designed for lower beam emittance and 3GeV full energy injection ramped up from 150MeV. It is a synchrotron accelerator of 496.8m in circumference and located concentric with the electron storage ring in the same tunnel. The vacuum system for the booster is divided into six super periods and each has nine bending magnet chambers. The beam duct is made of thin stainless steel tube extruded to the elliptical cross section with inner diameters of 35 mm×20 mm and thickness of 0.7 mm. All the chambers will be supported on the inner wall of the tunnel. The straightness of the extruded thin chambers is controlled within 2.5 mm in 4 m length. The bending chamber is made by mechanical bending from the straight tube. All the beam ducts will be chemical cleaned prior to welding, with flanges or BPM chambers, to form the long chambers in the clean room before installation. The arrangement of vacuum pumps are distributed to fulfill an average pressure of ＜1×10^-6 Pa. The detailed design and the construction status will be described in the paper.

WEPPD021

Optimization of the Ultra-High Vacuum Systems for the 3 GeV TPS Synchrotron Light Source

vacuum, impedance, photon, synchrotron

2543

G.-Y. Hsiung, C.K. Chan, C.-C. Chang, C.L. Chen, J.-R. Chen, C.M. Cheng, Y.T. Cheng, S-N. Hsu, H.P. Hsueh, Huang, Y.T. Huang, I.C. Sheng, L.H. Wu, Y.C. Yang
NSRRC, Hsinchu, Taiwan

The Taiwan Photon Source (TPS), a 3 GeV synchrotron light source, provides an ultra-low emittance of electron beam and the consequent extremely high brightness of photons. The vacuum pressure along the beam duct should be ultra-high vacuum (UHV) and even lower for reduction of the impact to the beam from the gas scattering or ion trapping troubles. Most of the outgas comes from the photon stimulated desorption (PSD) back streaming from downstream absorbers during beam operation and large area surface outgas inside the beam duct as well. Due to the anticipate request of the smallest vertical aperture of beam ducts from various insertion devices and the lowest broadband impedance through all the vacuum chambers of electron storage ring, the inner structure design and the surface treatment of vacuum chambers as well as the constraint of the back stream PSD outgas from distributed absorbers and the pumping locations should be optimized to obtain a high quality UHV system for the high stable synchrotron light source through the long period of operation. The optimized design of the vacuum chambers for the TPS will be described.

WEPPD024

A Study of Vacuum Pressure in TPS Cells

photon, vacuum, site, controls

2552

L.H. Wu, J.-R. Chen, C.M. Cheng, G.-Y. Hsiung, C.S. Huang, Huang, Y.T. Huang
NSRRC, Hsinchu, Taiwan

Recently, the type-2 and type-3 TPS cells are installed and pumped down into vacuum status. The pumping down curves of the type-2 and type-3cells, including R03, R06, R07, R10, and R11, are recorded after on-site welding and after assembling without leakage, individually. In the R03, R06, R07, R10 cells, the pumping down curve after assembling without leakage is a little higher than that after on-site welding. In those four cells, the pumping down curve after assembling all vacuum components and pumps is similar. However, in the R11 cell, it was found that the pumping down curve after assembling without leakage is almost along that of after on-site welding. The slope of pumping down curve near 1 hour in the R11 cell is -1.52, while that in the R10 cell is -1.39. It means that the vacuum pressure in the R11 cell is apparently improved. It is confirmed that the vacuum chambers are cleaned by the same process and the assembling components are similar. Besides, the photon stopper chambers are all pre-baked to 200 oC for the same time. We try to investigate the residual gas analysis (RGA) data to find the true reasons.

WEPPD025

LHC Detector Vacuum System Consolidation for Long Shutdown 1 (LS1) in 2013-2014

vacuum, ion, background, radiation

2555

M.A. Gallilee, J. Chaure, P. Cruikshank, J.E. Gallagher, C. Garion, J.M. Jimenez, R. Kersevan, H. Kos, L. Leduc, P. Lepeule, N. Provot, H. Rambeau, R. Veness
CERN, Geneva, Switzerland

The LHC has ventured into unchartered territory for Particle Physics accelerators. A dedicated consolidation program is required between 2013 and 2014 to ensure optimal physics performance. The experiments, ALICE, ATLAS, CMS, and LHCb, will utilise this shutdown, along with the gained experience of three years of physics running, to make optimisations to the detectors. New vacuum technologies have been developed for the experimental areas, to be integrated during this first phase shutdown. These technologies include bellows, vacuum chambers and ion pumps in aluminium, new beryllium vacuum chambers, and composite mechanical supports. An overview of this first phase consolidation program for the LHC experiments is presented.

WEPPD031

A Transverse Electron Target for Heavy Ion Storage Rings

target, ion, interaction-region, simulation

2573

S. Geyer, O. Meusel
IAP, Frankfurt am Main, Germany
O.K. Kester
GSI, Darmstadt, Germany

Funding: supported by HIC for FAIR
A transverse electron target is a well suited concept for storage rings to investigate electron-ion interactions processes relevant for heavy ion accelerators. In comparison with an internal gas target, it promises a better energy resolution but still has the advantage, in contrast to an electron cooler, of access to the interaction region for photon and electron spectroscopy under large solid angles. The new electron target is suited for the use under the UHV requirements of a storage ring and realizes an open geometry for spectroscopy. A simple design based on electrostatic fields was chosen. The sheet beam application provides a higher perveance limit and a smaller potential depression than a cylindrical gun arrangement. The adjustable electron energy ranges between several 10eV and a few keV. The setup will be installed applying the so-called animated beam technique. The electron target is dedicated to the NESR at the new FAIR facility. First measurements are planned at a test bench and subsequent tests at the Frankfurt Low Energy Storage Ring (FLSR) are envisaged. An overview of the progress in the development of the transverse electron target will be given.

WEPPD034

Mechanical Design of a High Energy Beam Absorber for the Advanced Superconducting Test Accelerator (ASTA) at Fermilab

cryomodule, radiation, neutron, status

2582

C.M. Baffes, M.D. Church, J.R. Leibfritz, S.A. Oplt, I.L. Rakhno
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
A high energy beam absorber has been built for the Advanced Superconducting Test Accelerator (ASTA) at Fermilab. In the facility’s initial configuration, an electron beam will be accelerated through 3 TTF-type or ILC-type RF cryomodules to an energy of 750MeV. The electron beam will be directed to one of multiple downstream experimental and diagnostic beam lines and then deposited in one of two beam absorbers. The facility is designed to accommodate up to 6 cryomodules, which would produce a 75kW beam at 1.5GeV; this is the driving design condition for the beam absorbers. The beam absorbers consist of water-cooled graphite, aluminum and copper layers contained in a Helium-filled enclosure. This paper describes the mechanical implementation of the beam absorbers, with a focus on thermal design and analysis. In addition, the potential for radiation-induced degradation of the graphite is discussed.

WEPPD048

Laser Synchronization at REGAE using Phase Detection at an Intermediate Frequency

laser, controls, LLRF, feedback

2624

M. Felber, M. Hoffmann, U. Mavrič, H. Schlarb, S. Schulz
DESY, Hamburg, Germany
W. Jałmużna
TUL-DMCS, Łódź, Poland

A new linear accelerator is being set up for electron diffraction experiments at DESY. This machine, called REGAE (Relativistic Electron Gun for Atomic Exploration) is composed of a photo-cathode gun and a buncher cavity. It uses a single laser system for both, the generation of the electron bunches and for pump-probe experiments. The required timing jitter between the electron bunches and the laser pulses at the experiment is in the order of 10 fs rms. The conventional method for laser synchronization using RF technique to measure phase-jitter in the baseband is susceptible to distortions caused by ground-loops and electro-magnetic interference. At REGAE a new scheme for an RF-based laser synchronization is deployed. It uses a down-converter which mixes a higher harmonic of the laser repetition rate down to an intermediate frequency (IF). The IF is digitized and its phase calculated. This information is used for the feedback controller keeping the laser and the RF synchronized.

WEPPD052

Compression and Synchronization of MeV Scale Subpicosecond Electron Beams in a THz IFEL Interaction

undulator, laser, simulation, space-charge

2636

J.T. Moody, R.K. Li, P. Musumeci, C.M. Scoby, H.L. To
UCLA, Los Angeles, California, USA

Recent development of MW peak power THz sources from efficient optical rectification of broadband IR pulses by pulse front tilting has made available laser locked single cycle THz pulses suitable for compression and laser-synchronization of photoinjector generated subpicosecond electron beams. Three dimensional simulations have shown that a waveguided 8 pulse THz train can be used to interact with a sub picoseconds electron beam in an undulator to achieve compression and laser synchronization. We present a THz pulse train source currently under development at UCLA PBPL as well as detailed 3 dimensional simulations including the effect of the interaction on transverse beam quality.
DOE-BES No. DE-FG02-92ER40693 and DOE-BES No. DE-FG02-07ER46272

WEPPD053

The LLNL/UCLA High Gradient Inverse Free Electron Laser Accelerator

laser, undulator, acceleration, simulation

2639

J.T. Moody, P. Musumeci
UCLA, Los Angeles, California, USA
G.G. Anderson, S.G. Anderson, M. Betts, S.E. Fisher, D.J. Gibson, A.M. Tremaine, S.S.Q. Wu
LLNL, Livermore, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
We describe the Inverse Free Electron Accelerator currently under construction at Lawrence Livermore National Lab. Upon completion of this accelerator, high brightness electrons generated in the photoinjector blowout regime and accelerated to 50 MeV by S-band accelerating sections will interact with > 4 TW peak power Ti:Sapphire laser in a highly tapered 50 cm undulator and experience an acceleration gradient of >200 MeV/m. We present the final design of the accelerator as well as the results of start to end simulations investigating preservation of beam quality and tolerances involved with this accelerator.

WEPPD054

Development of Pulsed Laser Systems and Cathode-performance Studies for the S-DALINAC Polarized Injector

laser, cathode, cavity, vacuum

2642

M. Espig, C. Eckardt, J. Enders, Y. Fritzsche, N. Kurichiyanil, J. Lindemann, M. Wagner
TU Darmstadt, Darmstadt, Germany

A source of polarized electrons has recently been implemented at the superconducting Darmstadt electron linear accelerator S-DALINAC. We give an overview of the recent performance of the system. Photo-emission from a superlattice-GaAs photo-cathode is obtained from using either a DC diode laser or a short-pulse Ti:Sapphire laser system. For a robust pulsed quasi-cw operation, it is investigated whether a VECSEL system (Vertical-Cavity Surface-Emitting Laser) can be realized with a wavelength of 780 nm and a repetition rate of 3 GHz with pulse widths of a few picoseconds only. To enhance the availability and performance of the polarized source with respect to quantum efficiency, a separate atomic-hydrogen cleaning system for the cathodes is planned which will allow cathode treatment to be tested and optimized. Supported by DFG within CRC/SFB 634 and by the state of Hesse in the LOEWE-Center HIC for FAIR.

WEPPD055

Gamma-rays Generation with 3D 4-mirror Cavity for ILC Polarized Positron Source

cavity, laser, photon, scattering

2645

T. Akagi, S. Miyoshi
Hiroshima University, Graduate School of Advanced Sciences of Matter, Higashi-Hiroshima, Japan
S. Araki, Y. Funahashi, Y. Honda, T. Okugi, T. Omori, H. Shimizu, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
H. Kataoka, T. Kon
Seikei University, Japan
M. Kuriki, T. Takahashi
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
K. Sakaue, M. Washio
RISE, Tokyo, Japan
R. Tanaka, H. Yoshitama
Hiroshima University, Higashi-Hiroshima, Japan

We are conducting gamma-rays generation experiment by the laser-Compton scattering using a Fabry-Perot cavity. We developed a 3D 4-mirror cavity, and it is installed at the KEK-ATF. By using a 3D 4-mirror cavity, small laser spot can be achieved with stable resonant condition. In addition, we aim 1900 times enhancement of input laser power by a 4-mirror cavity to increase the number of gamma-rays.

WEPPD059

Proton Acceleration by a Relativistic Laser Frequency-Chirp Driven Plasma Snowplow

laser, plasma, proton, acceleration

2654

A. A. Sahai, T.C. Katsouleas
Duke ECE, Durham, North Carolina, USA
R. Bingham
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
W.B. Mori, A. Tableman, F.S. Tsung, M. Tzoufras
UCLA, Los Angeles, California, USA

Funding: NSF-PHY-0936278, NSF-PHY-0904039 and NSFPHY-0936266, US DOE DE-FC02-07ER41500 and DE-FG02-92ER40727, DOE Fusion Science Center through a University of Rochester Subcontract No. 415025-G.
We analyze the use of a relativistic laser pulse with a controlled frequency chirp incident on a rising plasma density gradient to drive an acceleration structure for proton and light ion acceleration. The Chirp Induced Transparency Acceleration (ChITA) scheme is described with an analytical model of the velocity of the snowplow at critical density on a pre-formed rising plasma density gradient that is driven by positive chirp in the frequency of a relativistic laser pulse. The velocity of the ChITA-snowplow is shown to depend upon rate of rise of the frequency of the relativistic laser pulse, the normalized magnetic vector potential of the laser pulse and the plasma density gradient scale-length. We observe using 1-D OSIRIS simulations the formation and forward propagation of ChITA-snowplow, being continuously pushed by the chirping laser at a velocity in accordance with the analytical results. The trace protons reflect off of this propagating snowplow structure and accelerate monoenergetically. The control over ChITA-snowplow velocity allows the tuning of accelerated proton energies.

WEPPD060

A Drive Laser for Multi-bunch Photoinjector Operation

laser, brightness, cathode, emittance

2657

D.J. Gibson, C.P.J. Barty, M. J. Messerly, M.A. Prantil
LLNL, Livermore, California, USA
E. Cormier
CELIA, Talence, France

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344
Numerous electron beam applications would benefit from increased average current without sacrificing beam brightness. Work is underway at LLNL to investigate the performance of X-band photoinjectors that would generate electron bunches at a rate matching the RF drive frequency, i.e. one bunch per RF cycle. A critical part of this effort involves development of photo-cathode drive laser technology. Here we present a new laser architecture that can generate pulse trains at repetition rates up to several GHz. This compact, fiber-based system is driven directly by the accelerator RF and so is inherently synchronized with the accelerating fields, and scales readily over a wide range of drive frequencies (L-band through X-band). The system will be required to produce 0.5 μJ, ~200 fs rise time, spatially and temporally shaped UV pulses designed to optimize the electron beam brightness. Presented is the current status of this system, producing pulses shorter than 2 ps from a cw source.

WEPPD063

Construction of Disk-loaded Buncher for S-Band Low Energy TW Electron Linear Accelerator

linac, impedance, coupling, cavity

2666

F. Ghasemi, F. AbbasiDavani, S. Ahmadiannamini, M.Sh. Shafiee
sbu, Tehran, Iran
M.L. Lamehi Rashti, H. Shaker
IPM, Tehran, Iran

The project of design and construction of Traveling linear electron accelerator is being performed by the Institute for Research in Fundamental Sciences (IPM) and Shahid Beheshti University in Iran. By using the results of the calculations and by dynamic simulation of electron beam in the designed buncher, the dimensions of the designed sample have been obtained. This paper discuss construction of this buncher.

WEPPD064

Quick Recovery of the KEK e⁻/e⁺ Injector Linac from the Great East Japan Earthquake

linac, vacuum, injection, positron

2669

A. Enomoto
KEK, Ibaraki, Japan

The KEK e⁻/e⁺ injector linac is under operation for the KEK Photon Factory (PF) storage ring and Photon Factory - Advanced Ring (PF-AR). And the linac has just started the upgrade for the SuperKEKB project. On March 11, the linac suffered great damage from the Great East Japan Earthquake. Due to an extraordinary strong vibration, many bellows of vacuum pipes were violently torn and the entire linac vacuum was exposed to the atmosphere. Without electricity, highly humid air entered the inside of accelerator structures. Some people supposed the linac would not be recovered within a year. However, it resumed operation after only two months. We report the memorable disaster and how we recovered the linac so quickly.

WEPPD069

PLS-II Linac Upgrade

linac, klystron, gun, emittance

2681

B.-J. Lee, J.Y. Choi, S. Chunjarean, T. Ha, J.Y. Huang, I. Hwang, Y.D. Joo, C. Kim, M. Kim, S.H. Kim, S.J. Kwon, S.H. Nam, S.S. Park, S.J. Park, S. Shin, Y.G. Son
PAL, Pohang, Kyungbuk, Republic of Korea

This paper reports on the recent status of the Pohang Light Source (PLS)-II linac at Pohang Accelerator Laboratory (PAL). From 2009, the linac upgrade has been started increasing its energy from 2.5 GeV to 3 GeV aiming stable top-up mode operation. First, we show that the stability status of the two different types of modulators to meet the top-up condition which requires very stable modulator system in linac. Next, we introduce upgrade status those differ from their PLS (2.5 GeV) such as installation of the dual vacuum systems for the electron gun to replace it immediately, adding important diagnostic tools, and reutilization of the beam analysis system just after pre-injector. Finally we present the electron beam parameters measured by those diagnostic system.

WEPPD077

Generation of Picosecond Electron-bunch Trains with Variable Spacing Using a Multi-pulse Photocathode Laser

laser, quadrupole, wakefield, simulation

2705

P. Piot
Fermilab, Batavia, USA
M.E. Conde, W. Gai, C.-J. Jing, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof
ANL, Argonne, USA
D. Mihalcea, P. Piot, M.M. Rihaoui
Northern Illinois University, DeKalb, Illinois, USA

Funding: Work supported by DOE awards FG-02-08ER41532 and DE-AC02-06CH11357.
We demonstrate the generation of a train of electron bunches with variable spacing at the Argonne Wakefield Accelerator. The photocathode ultraviolet laser pulse consists of a train of four pulses produced via polarization splitting using two alpha-BBO crystals. The photoemitted electron bunches are then manipulated in a horizontally-bending dogleg with variable longitudinal dispersion. A downstream vertically-deflecting cavity is then used to diagnose the temporal profile of the electron beam. The generation of a train composed of four bunches with tunable spacing is demonstrated. Such train of bunch could have application to, e.g., the resonant excitation of wakefield in dielectric-lined waveguides.

WEPPD081

Optimization of AC Dipole Parameters for the Mu2e Extinction System

dipole, proton, emittance, magnet-design

2714

E. Prebys
Fermilab, Batavia, USA

The Mu2e experiment is being planned at Fermilab to measure the rate for muons to convert to electrons in the field of an atomic nucleus with unprecedented precision. This experiment uses an 8 GeV primary proton beam consisting of short (~200 nsec FW) bunches, separated by 1.7 μs. It is vital that out-of-bunch beam be suppressed at the level of 10^-10 or less. This poster describes the parametric analysis which was done to determine the optimum harmonics and magnet specifications for this system, as well as the implications for the beam line optics.

WEPPD084

The E-Lens Test Bench for Rhic Beam-Beam Compensation

gun, controls, dipole, cathode

2720

X. Gu, Z. Altinbas, J.N. Aronson, E.N. Beebe, W. Fischer, D.M. Gassner, K. Hamdi, J. Hock, L.T. Hoff, P. Kankiya, R.F. Lambiase, Y. Luo, M. Mapes, J.-L. Mi, T.A. Miller, C. Montag, S. Nemesure, M. Okamura, R.H. Olsen, A.I. Pikin, D. Raparia, P.J. Rosas, J. Sandberg, Y. Tan, C. Theisen, P. Thieberger, J.E. Tuozzolo, W. Zhang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
To compensate for the beam-beam effects from the proton-proton interactions at IP6 and IP8 in the Relativistic Heavy Ion Collider (RHIC), we are fabricating two electron lenses that we plan to install at RHIC IR10. Before installing the e-lenses, we are setting-up the e-lens test bench to test the electron gun, collector, GS1 coil, modulator, partial control system, some instrumentation, and the application software. Some e-lens power supplies, the electronics for current measurement will also be qualified on test bench. The test bench also was designed for measuring the properties of the cathode and the profile of the beam. In this paper, we introduce the layout and elements of the e-lens test bench; and we discuss its present status towards the end of this paper.

WEPPP003

Focusing of Accelerated Particles by Wakefields of a Drive Bunch in a Plasma-dielectric Waveguide

plasma, wakefield, focusing, acceleration

2723

G.V. Sotnikov, R.R. Kniaziev
NSC/KIPT, Kharkov, Ukraine

Funding: The research is supported in part by the Science and Technology Center in Ukraine (STCU), project No. P522.
One of wakefield acceleration methods as a slowing medium uses the plasma of a capillary discharge*. The capillary tube is a slowing medium, therefore at propagation in it of a laser pulse or relativistic electron bunches (REB) along with plasma wakefields will be excited an eigen waves of dielectric structure. So far influence of electrodynamic properties of capillary tube material on plasma wakefields is not investigated. On an example of a cylindrical waveguide of gigahertz operation frequency range, we investigate excitation of wakefields by REB in a dielectric waveguide (DW) with the accelerating channel filled with isotropic plasma. The excited field consists of Langmuir wave fields (LW) and fields of eigen waves of DW. At certain plasma density a longitudinal electric field of LW it is significantly less than the similar of DW waves , and transverse components of the LW field are significantly higher than transverse component of DW waves. The periods of these two types of waves generally do not coincide. The range of plasma densities which provides a simultaneous acceleration and focusing of test bunch by LW is found.
* Steinhauer L.C., Kimura W.D. Phys. Rev. STAB. V.9, 081301 (2006).

WEPPP006

Using Simulations to Understand Particle Dynamics and Resonance in the Micro-accelerator Platform

laser, resonance, coupling, acceleration

2732

J.C. McNeur, G. Travish
UCLA, Los Angeles, USA
H. Hairong
UESTC, Chengdu, Sichuan, People's Republic of China
R.B. Yoder
Manhattanville College, Purchase, New York, USA

Funding: Work funded in part by grant HDTRA1-09-1-0043 from the US Defense Threat Reduction Agency and under a grant from NNSA/NA-221 Office of Nonproliferation and Verification Research and Development.
The Micro-Accelerator Platform (MAP) is a slab-symmetric micron-scale electron accelerator. Electrons gain energy via a standing wave electromagnetic resonance powered by a side coupled Ti:Sapphire laser. In this paper, we will discuss simulations of resonance and particle dynamics in this structure. Three-dimensional simulations showing evidence of stable 1 GeV/m acceleration are detailed along with simulations studying defocusing and wakefield effects in the MAP. Additionally, optimization of the structure and the coupling of laser power into the cavity will be explored.

WEPPP008

Vacuum Laser Acceleration Experiment Perspective at Brookhaven National Lab-Accelerator Test Facility

laser, acceleration, vacuum, simulation

2735

X.P. Ding, D.B. Cline, L.S. Shao
UCLA, Los Angeles, California, USA
M.G. Fedurin, K. Kusche, I. Pogorelsky, V. Yakimenko
BNL, Upton, Long Island, New York, USA
Y.K. Ho, Q. Kong
Fudan University, Shanghai, People's Republic of China
J.J. Xu
Shanghai Institute of Optics and Fine Mechanics, Shanghai, People's Republic of China

Funding: Supported by the DOE under award number DE-FG02-92ER40695 (UCLA)
This paper presents the pre-experiment plan and prediction of the first stage of Vacuum Laser Acceleration (VLA) collaborating by UCLA, Fudan University and ATF-BNL. This first stage experiment is a Proof-of-Principle to support our previously posted novel VLA theory. Simulations show that based on ATF’s current experimental conditions, the electron beam with initial energy of 15MeV can get net energy gain from intense CO2 laser beam. The difference of electron beam energy spread is observable by ATF beam line diagnostics system. Further this energy spread expansion effect increases along with the laser intensity increasing. The proposal has been approved by ATF committee and experiment will be the next project.

WEPPP009

Experimental Progress Towards a Resonant Slab-symmetric Dielectric Laser Accelerator

simulation, laser, acceleration, vacuum

2738

G. Travish, K.S. Hazra, G. Liu, J.C. McNeur, E.B. Sozer, J. Zhou
UCLA, Los Angeles, California, USA
H. Hairong
UESTC, Chengdu, Sichuan, People's Republic of China
R.B. Yoder
Manhattanville College, Purchase, New York, USA

Funding: Work funded in part by grant HDTRA1-09-1-0043 from the US Defense Threat Reduction Agency and under a grant from NNSA/NA-221 Office of Nonproliferation and Verification Research and Development.
TheμAccelerator Platform (MAP), a resonant dielectric structure for laser acceleration of electrons, has been in development for a number of years. It consists of a a vacuum gap between two slab-shaped reflecting boundaries, with a transmissive grating diffractive optic on one boundary that allows laser power to propagate into the gap and enforces an accelerating mode. We report on the progress of bench and beam tests carried out within the last year, and the challenges faced in diagnosing <pC beams from optical-scale structures. We also describe refinements to our fabrication techniques and lessons learned during the development of the fabrication process.

WEPPP010

FACET: SLAC's New User Facility

positron, acceleration, wakefield, linac

2741

C.I. Clarke, F.-J. Decker, R.J. England, R.A. Erickson, C. Hast, M.J. Hogan, S.Z. Li, M.D. Litos, Y. Nosochkov, J.T. Seeman, J. Sheppard, U. Wienands, M. Woodley, G. Yocky
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
FACET (Facility for Advanced Accelerator Experimental Tests) is a new User Facility at SLAC National Accelerator Laboratory. The first User Run started in spring 2012 with 20 GeV, 3 nC electron beams. The facility is designed to provide short (20 um) bunches and small (20 um wide) spot sizes, producing uniquely high power beams. FACET supports studies from many fields but in particular those of Plasma Wakefield Acceleration and Dielectric Wakefield Acceleration. The creation of drive and witness bunches and shaped bunch profiles is possible with "Notch" Collimation. FACET is also a source of THz radiation for material studies. Positrons will be available at FACET in future user runs. We present the User Facility and the available tools and opportunities for future experiments.

WEPPP011

Multi-Cavity Proton Cyclotron Accelerator: An Electron Counterpart

cavity, proton, cyclotron, acceleration

2744

M.A. LaPointe, S.V. Shchelkunov
Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
J.L. Hirshfield
Omega-P, Inc., New Haven, USA
V.P. Yakovlev
Fermilab, Batavia, USA

Funding: Supported by the Department of Energy, Office of Nuclear Physics.
A multi-cavity multi-frequency proton cyclotron accelerator has been proposed. It would utilize cyclotron resonance in each of eight cavities of uniformly diminishing frequency in a uniform magnetic field to comprise a compact (25 m) 1 GeV proton accelerator, according to simulation results*. A four cavity electron counterpart is under construction to test the mechanism of the multi-cavity setup, including phase acceptance, energy gain, and growth of energy spread and emittance for parameters equivalent to the proton case. The four electron counterpart cavities are driven by kW-level phase coherent RF sources at 1.5, 1.8, 2.1 and 2.4 GHz. Each cavity operates in the rotating TE111 mode and includes two feeds in quadrature to drive the rotating mode and two RF pickoffs for diagnostics. The electron beam source is a low-current gun with a BaO cathode which operates at -1200V and <50 microamps. After traversing the cavities, the beam is collected on either a Faraday cup or is imaged with a phosphor screen. Details of the setup and initial results from experiments with the four cavity electron counterpart will be presented.
* M.A. LaPointe, V.P. Yakovlev, S.Yu. Kazakov, and J.L. Hirshfield, Proc. of PAC 2009, May 4-8,Vancouver, BC, Canada, pp.3045-3047 (2011).

WEPPP014

Modeling of Quasi-phase Matching in an Aperiodic Corrugated Plasma Waveguide for High-efficiency Direct Laser Electron Acceleration

plasma, laser, acceleration, simulation

2750

M.W. Lin
The Pennsylvania State University, University Park, Pennsylvania, USA
I. Jovanovic
Penn State University, University Park, Pennsylvania, USA

Funding: This work is supported by the Defense Threat Reduction Agency through contract HDTRA1-10^-1-0034.
Direct laser acceleration (DLA) of charged particles using the axial electric field of a radially polarized intense laser pulse has the potential to realize a compact accelerator required in security and medical applications. The implementation of guided propagation of laser pulses over long distances and the phase matching between electrons and laser pulses may limit the performance of DLA in reality*. A corrugated plasma waveguide could be applied to extend the laser beam propagation distance and for quasi-phase matching between laser and electron pulses for net acceleration. To accelerate electrons from a low initial energy (for example, ~5 MeV from a photoinjector gun) up to hundreds of MeV, an aperiodic corrugated plasma waveguide with successive increase of on-axis density modulation period is needed**. We conducted particle-in-cell simulations to design the appropriate aperiodic plasma structure for DLA. For each section of the corrugated waveguide, the dependence of density modulation period on the initial electron energy and laser pulse intensity is investigated. The simulation results are guiding the design of proof-of-principle experiments for compact, tabletop DLA.
* P. Serafim, et al., IEEE Trans. Plasma Sci. 28, 1155 (2000).
** J. P. Palastro, et al., Phys. Rev. E. 77, 036405 (2008).

WEPPP015

Generation and Characterization of 5-micron Electron Beam for Probing Optical Scale Structures

diagnostics, quadrupole, permanent-magnet, target

2753

M.G. Fedurin, M. Babzien, V. Yakimenko
BNL, Upton, Long Island, New York, USA
B.A. Allen
USC, Los Angeles, California, USA
P. Muggli
MPI, Muenchen, Germany
A.Y. Murokh
RadiaBeam, Santa Monica, USA

In recent years advanced acceleration technologies have progress toward combination of electron beam, laser and optical scale dielectric structures. In present paper described generation of the electron beam probe with parameters satisfied to perform test of such optical structures.

WEPPP016

De-neutralization of Laser Produced Proton Pulse in a Strong Solenoidal Magnetic Field

proton, simulation, focusing, laser

2755

M. Droba, O.K. Kester, O. Meusel, C. Wiesner
IAP, Frankfurt am Main, Germany

Laser generated proton pulses of ten to several ten MeV produced in PHELIX-laser facility at GSI Darmstadt poses some unique characteristics. The first systematic exploration of the interface between proton pulse generation via the TNSA mechanism and conventional accelerator technology is within the scope of the LIGHT (Laser Ion Generation, Handling and Transport) project. One of the main tasks is to study the beam dynamics in intense B-fields, especially in context of early de-neutralization and space charge effects. The 3D numerical simulations with co-moving electrons and up to 10⁷ macroparticles were performed to investigate the de-neutralization process in the focusing magnetic solenoid. Importance of the first focusing element and influence on beam parameters will be addressed. Results of the 3D simulation model will be presented and discussed.

WEPPP017

Recent Results at the SPARC_LAB Facility

laser, plasma, injection, photon

2758

M. Ferrario, D. Alesini, M.P. Anania, M. Bellaveglia, R. Boni, M. Castellano, E. Chiadroni, G. Di Pirro, A. Drago, A. Esposito, A. Gallo, C. Gatti, G. Gatti, A. Ghigo, T. Levato, E. Pace, L. Pellegrino, R. Pompili, A.R. Rossi, B. Spataro, P. Tomassini, C. Vaccarezza, F. Villa
INFN/LNF, Frascati (Roma), Italy
A. Bacci, C. De Martinis, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
G. Dattoli, E. Di Palma, L. Giannessi, A. Petralia, M. Quattromini, C. Ronsivalle, I.P. Spassovsky, V. Surrenti
ENEA C.R. Frascati, Frascati (Roma), Italy
D. Di Giovenale
INFN-Roma II, Roma, Italy
U. Dosselli
INFN, Roma, Italy
R. Faccini
INFN-Roma, Roma, Italy
R. Fedele
Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli, Italy
M. Gambaccini
INFN-Ferrara, Ferrara, Italy
D. Giulietti
UNIPI, Pisa, Italy
L.A. Gizzi, L. Labate
CNR/IPP, Pisa, Italy
P. Londrillo
INFN-Bologna, Bologna, Italy
S. Lupi
Università di Roma I La Sapienza, Roma, Italy
A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy
G. Passaleva
INFN-FI, Sesto Fiorentino, Italy
V. Petrillo
Universita' degli Studi di Milano, Milano, Italy
J.V. Rau
ISM-CNR, Rome, Italy
G. Turchetti
Bologna University, Bologna, Italy

A new facility named SPARC_LAB (Sources for Plasma Accelerators and Radiation Compton with Lasers and Beams) has been recently launched at the INFN National Labs in Frascati, merging the potentialities of the old projects SPARC and PLASMONX. The SPARC project, a collaboration among INFN, ENEA and CNR, is now completed, hosting a 150 MeV high brightness electron beam injector which feeds a 12 meters long undulator. Observation of FEL radiation in the SASE, Seeded and HHG modes has been performed from 500 nm down to 40 nm wevelength. A second beam line has been also installed to drive a narrow band THz radiation source. In parallel to that, INFN decided to host a 300 TW laser that will be linked to the linac and devoted to explore laser-matter interaction, in particular with regard to laser-plasma acceleration in the self injection and external injection modes, (the PLASMONX experiments). The facility will be also used for particle driven plasma acceleration experiments (the COMB experiment). A Thomson scattering experiment coupling the electron bunch to the high-power laser to generate coherent monochromatic X-ray radiation is also in the commissioning phase.

WEPPP019

Designing of Photonic Crystal Accelerator for Radiation Biology

laser, vacuum, injection, acceleration

2763

K. Koyama, Y. Matsumura
University of Tokyo, Tokyo, Japan
A. Aimidula, M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
T. Natsui, M. Yoshida
KEK, Ibaraki, Japan

Funding: This work was performed as part of the Global COE Program (Nuclear Education and Research Initiative, MEXT, Japan.
A photonic crystal accelerator with a combination of a fiber laser is under development in order to apply it to the radiation biology. In order to investigate fundamental biological processes in a cell, a DNA is precisely shot by an electron bunch with an in situ observation of a radiation interaction using a microscope. Required beam diameter, bunch length, and beam energy are nanometer, attosecond, and 100 keV to 1 MeV, respectively. A photonic crystal or dielectric laser accelerator energized by a fiber laser is suitable for producing such a fine beam with a palm top device. A preliminary estimation shows that 200 keV electron bunch is available from a 0.8-mm-long accelerator and a few cm electron gun, which is driven by a few μJ, 5-ps laser pulse. We are developing a fiber laser in order to drive the photonic crystal accelerator. The Yb-fiber oscillator delivers mode-locked pulse train of ≈5 nJ/pulse at the repetition frequency of 62.5 MHz. The output pulse will be increased to several μJ by adopting a fiber amplifier

WEPPP022

Analysis of a Rectangular Dielectric-lined Accelerating Structure with an Anisotropic Loading

wakefield, radiation, acceleration, impedance

2769

I.L. Sheynman, S. Baturin
LETI, Saint-Petersburg, Russia
A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: Russian Fund of Basic Research Federal target program "Scientific and scientific and pedagogical personnel of innovative Russia" of the Ministry of Education and Science of Russia.
Analysis of Cherenkov radiation generated by high current relativistic electron bunch passing through a rectangular waveguide with anisotropic dielectric loading has been carried out. Some of the materials used for the waveguide loading of accelerating structures (sapphire) possess significant anisotropic properties. In turn, it can influence excitation parameters of the wakefields generated by an electron beam. Using orthogonal eigenmodes decomposition for the rectangular dielectric waveguide, the analytical expressions for the wakefields have been obtained. Numerical modeling of the longitudinal and transverse (deflecting) wakefields has been carried out as well. It is shown that the dielectric anisotropy causes frequency shift in comparison to the dielectric-lined waveguide with the isotropic dielectric loading.

WEPPP025

A Test-bed for Future Linear Collider Technology: Argonne Wakefield Accelerator Facility (AWA)

wakefield, gun, linac, acceleration

2778

M.E. Conde, D.S. Doran, W. Gai, R. Konecny, W. Liu, J.G. Power, Z.M. Yusof
ANL, Argonne, USA
S.P. Antipov, C.-J. Jing
Euclid TechLabs, LLC, Solon, Ohio, USA
E.E. Wisniewski
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357.
Research at the AWA Facility has been focused on the development of electron beam driven wakefield structures. Accelerating gradients of up to 100 MV/m have been excited in dielectric loaded cylindrical structures operating in the microwave range of frequencies. Several upgrades, presently underway, will enable the facility to explore higher accelerating gradients, and also be able to generate longer RF pulses of higher intensity. The upgraded 75 MeV drive beam will consist of bunch trains of up to 32 bunches spaced by 0.77 ns with up to 100 nC per bunch. The RF pulses generated by the drive bunches are expected to reach GW power levels, establishing accelerating gradients of hundreds of MV/m.

WEPPP026

Dielectric-plate-implanted Higher Order Mode (HOM) Waveguide for High Intensity Multi-beam Device Application

HOM, simulation, wakefield, lattice

2781

Y.-M. Shin
Fermilab, Batavia, USA

A mode-selective oversized RF-beam channel has been investigated for high intensity multi-beam devices. Implanting the equi-spaced dielectric plates at the transverse positions where longitudinal electric fields of a HOM are minimal in the micro-metallic structure strongly suppresses all lower energy modes and other wakefield modes. The dielectric lattice captures only a single HOM of the wavelengths that correspond to the plate spacing. Electromagnetic simulations have shown that the lower energy modes, TE10 and TE20 modes, are suppressed down to < ~ -60 dB by two plate loads, while TE310-mode prominently propagates through the 2 mm long waveguide only with 4 dB (= -2dB/mm) at 1 THz. The numerical calculation indicated that the TE30 mode has ~ a few times higher Q than the lower energy modes. The strong single mode selectivity has been extensively looked into with a more highly overmoded structure. Feasibility analysis of the HOM structure for multi-beam device application is under investigation. Particle-in-cell (PIC) simulation has shown coherent beam bunching and energy gain from THz driving signal.

WEPPP027

PBG-slab Embedded Traveling Wave Structure for Planar Beam Accelerator Application

HOM, acceleration, photon, lattice

2784

Y.-M. Shin
Fermilab, Batavia, USA

The oversized traveling wave (TE10-mode) channel integrated with the photonic-band-gap (PBG) slab arrays have been investigated for planar beam accelerator application. Simulation analysis showed that the slab arrays allow only the PBG-modes (5-6 GHz) to propagate with ~ 2 dB of insertion loss, corresponding to ~ 1.14 dB/cm attenuation, which thereby effectively suppresses trapped non-PBG modes down to ~ -14.3 dB/cm. It will enable monochromatic propagation of fundamental acceleration modes along the heavily over-moded planar waveguide without anomalous excitation of unstable trapped HOMs. The saturated maximum field gradients of the accelerating structure have been analyzed with respect to operational frequency bands corresponding to structural sizes. The field gradient of the guided PBG-mode has been investigated with finite-integral-method (FIM) simulations at W-band. This mode-filter could be utilized for HOM dampers in high aspect ratio (HAR) planar beam accelerators. An experimental test is currently under consideration.

WEPPP030

Experimental Generation of a Double-bunch Electron Beam by Transverse-to-Longitudinal Phase Space Exchange

laser, focusing, cathode, gun

2789

T.J. Maxwell, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
A.S. Johnson, A.H. Lumpkin, J. Ruan, Y.-E. Sun, R.M. Thurman-Keup
Fermilab, Batavia, USA

Funding: Supported by Fermi Research Alliance, LLC under U.S. Dept. of Energy Contract No. DE-AC02-07CH11359, and Northern Illinois Univ. under US Dept. of Defense DURIP program Contract N00014-08-1-10⁶⁴.
In this paper we demonstrate the generation of a tunable, longitudinal double-pulse electron beam. Experimental results on the generation of electron bunch trains with sub-picosecond structure have been previously reported where an initial transverse electron beam modulation was produced by masking the electron beam directly*. Here the initial transverse structure is imparted by masking of the photoinjector drive laser to effectively produce two horizontally offset beams at photoemission in the RF gun. A longitudinal double-pulse modulation is then realized after a transverse-to-longitudinal phase-space exchange beamline. Longitudinal profile tuning is demonstrated by upstream beam focusing in conjunction with downstream monitoring of single-shot electro-optic spectral decoding of coherent transition radiation.
* Y.-E. Sun et al., Tunable Subpicosecond Electron-Bunch-Train Generation Using a Transverse-To-Longitudinal Phase-Space Exchange Technique, Phys. Rev. Lett. 10⁵, 234801 (2010).

WEPPP031

To the Possibility of Bound States between Two Electrons

emittance, damping, positron, proton

2792

A.A. Mikhailichenko
CLASSE, Ithaca, New York, USA

We analyze the possibility to compress dynamically the polarized electron bunch so that the distance between some electrons in the bunch comes close to the Compton wavelength, arranging a bound state, as the attraction by the magnetic momentum-induced force at this distance dominates repulsion by the electrostatic force for the appropriately prepared orientation of the magnetic moments of the electron-electron pair. This electron pair behaves like a boson now, so the restriction for the minimal emittance of the beam becomes eliminated. Some properties of such degenerated electron gas represented also.

WEPPP032

Inverse Free Electron Laser Acceleration Using Ultra-fast Solid State Laser Technology

laser, undulator, simulation, acceleration

2795

S.G. Anderson, G.G. Anderson, S.M. Betts, S.E. Fisher, D.J. Gibson, A.M. Tremaine, S.S.Q. Wu
LLNL, Livermore, California, USA
J.T. Moody, P. Musumeci
UCLA, Los Angeles, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
We present a theoretical and computational study of the application of Ti:Sapphire laser technology to Inverse Free Electron Laser (IFEL) accelerators. Specifically, the regime in which the number of undulator periods is comparable to the number of cycles in the laser pulse is investigated and modifications to the IFEL accelerator equations and laser requirements are given. 1-D and 3-D simulations are used to study the IFEL interaction in this regime. In addition, the effects of non-Gaussian laser pulses, and astigmatic aberrations in the laser focus are analyzed. Finally, the tools developed for this study are applied to the LLNL/UCLA IFEL experiment, and potential future IFEL designs.

WEPPP033

Design of a Wakefield Experiment in a Traveling-wave Photonic Band Gap Accelerating Structure

wakefield, higher-order-mode, target, HOM

2798

E.I. Simakov, R.L. Edwards
LANL, Los Alamos, New Mexico, USA

Funding: This work is supported by the U.S. Department of Energy (DOE) Office of Science Early Career Research Program.
We designed an experiment to conduct a thorough investigation of higher order mode spectrum in a room-temperature traveling-wave photonic band gap (PBG) accelerating structure at 11.7 GHz. It has been long recognized that PBG structures have great potential in reducing long-range wakefields in accelerators. The first ever demonstration of acceleration in room-temperature PBG structures was conducted at MIT in 2005. Since then, the importance of that device has been recognized by many research institutions. However, the full experimental characterization of the wakefield spectrum in a beam test has not been performed to date. The Argonne Wakefield Accelerator (AWA) test facility at the Argonne National Laboratory represents a perfect site where this evaluation could be conducted with a single high charge electron bunch and with a train of bunches. We present the design of the accelerating structure that will be tested at AWA in the near future. The structure will consist of sixteen 2pi/3 PBG cells, including two coupler cells. We will also present the results of the initial cold-testing of the few sample cells and a plan for the beam test.

WEPPP035

Pushing the Gradient Limitations of Superconducting Photonic Band Gap Structure Cells

SRF, HOM, wakefield, higher-order-mode

2801

E.I. Simakov, W.B. Haynes, S.S. Kurennoy, J.F. O'Hara, E.R. Olivas, D.Y. Shchegolkov
LANL, Los Alamos, New Mexico, USA

Funding: This work is supported by the Department of Defense High Energy Laser Joint Technology Office through the Office of Naval Research.
We present a design of a superconducting photonic band gap (PBG) accelerator cell operating at 2.1 GHz. The cell is designed with the PBG rods that are specially shaped to reduce the peak magnetic fields and at the same time to preserve its effectiveness for suppression of the higher order modes (HOMs). It has been long recognized that PBG structures have great potential in reducing and even completely eliminating HOMs in accelerators. This is especially beneficial for superconducting electron accelerators for high power free-electron lasers (FELs), which are intended to provide high current continuous duty electron beams. Using PBG structures to reduce the prominent beam-breakup phenomena due to HOMs will allow significantly increased beam-breakup thresholds, and consequently will allow the increase of the frequency of SRF accelerators and the development of novel compact high-current accelerator modules for FELs. High gradient limitations of PBG resonators and the optimal arrangement of the wakefield couplers will be discussed in details in this presentation.

WEPPP036

Undulator Commissioning for a High-Energy-Gain Inverse Free Electron Laser Experiment

undulator, laser, simulation, acceleration

2804

J.P. Duris, R.K. Li, P. Musumeci, E.W. Threlkeld
UCLA, Los Angeles, California, USA

Funding: This work was supported by DOE grant DE-FG02-92ER40693 and Defense of Threat Reduction Agency award HDTRA1-10^-1-0073.
We present the construction and measurement details of a strongly tapered helical undulator for the Rubicon Inverse Free Electron Laser (IFEL) experiment. Results of the magnetic field measurements are presented, and these are used to produce simulations of the expected performance of the experiment. Finally, a study of the tolerances on the input parameters of the experiment is presented.

WEPPP037

Experimental Study of Self Modulation Instability of ATF Electron Beam

plasma, simulation, wakefield, proton

2807

Y. Fang
USC, Los Angeles, California, USA
M. Babzien, M.G. Fedurin, K. Kusche, R. Malone, V. Yakimenko
BNL, Upton, Long Island, New York, USA
W.B. Mori
UCLA, Los Angeles, California, USA
P. Muggli
MPI, Muenchen, Germany
L.O. Silva, J. Vieira
Instituto Superior Tecnico, Lisbon, Portugal

Funding: US. Department of Energy.
We demonstrate experimentally for the first time the self-modulation of a relativistic electron bunch in a plasma. This demonstration serves as a proof-of-principle test for the mechanisms of transverse self-modulation of particle bunches in plasmas. It indicates the possibility of using long electron or proton bunches as drivers for plasma based accelerators. The long (~5ps) bunch available at BNL-ATF is used in this experiment and in the particle-in-cell OSIRIS. We use the 2D version for cylindrically symmetric geometries. The energy of the beam particles is measured after the plasma exit in the experiment. The obvious energy gain and loss by electrons indicates the excitation of longitudinal wakefields, and hence of transverse focusing fields. Both simulations and experiments show that the electron beamlets are formed at the scale of the plasma wavelength, and the number of beamlets changes as the plasma density is varied. We also measured the variation in beam transverse size downstream from the plasma as well as the variations in coherent transition radiation energy to demonstrate the effect of transverse self–modulation.

WEPPP041

Wakefield Breakdown Test of a Diamond-loaded Accelerating Structure at the AWA

wakefield, laser, vacuum, simulation

2813

S.P. Antipov, J.E. Butler, C.-J. Jing, A. Kanareykin, P. Schoessow, S.S. Zuo
Euclid TechLabs, LLC, Solon, Ohio, USA
S. Baryshev, M.E. Conde, D.S. Doran, W. Gai, R. Konecny, J.G. Power, Z.M. Yusof
ANL, Argonne, USA

Funding: DOE SBIR
Diamond has been proposed as a dielectric material for dielectric loaded accelerating (DLA) structures. It has a very low microwave loss tangent, the highest available thermoconductive coefficient and high RF breakdown field. In this paper we report results from a wakefield breakdown test of diamond-loaded rectangular accelerating structure. The high charge beam from the AWA linac (~70 nC, σz = 2.5mm) will be passed through a rectangular diamond - loaded resonator and induce an intense wakefield. A groove is cut on the diamond to enhance the field. Electric fields up to 0.5 GV/m will be present on the diamond surface to attempt to initiate breakdown. A surface analysis of the diamond is be performed before and after the beam test.

WEPPP042

Experimental Demonstration of Wakefield Effects in a 250 GHz Planar Diamond Accelerating Structure

wakefield, dipole, radiation, acceleration

2816

S.P. Antipov, J.E. Butler, C.-J. Jing, A. Kanareykin, P. Schoessow, S.S. Zuo
Euclid TechLabs, LLC, Solon, Ohio, USA
M.G. Fedurin, K. Kusche, V. Yakimenko
BNL, Upton, Long Island, New York, USA
W. Gai
ANL, Argonne, USA

Funding: DOE SBIR
We have directly measured the mm-wave wake fields induced by subpicosecond, intense relativistic electron bunches in a diamond loaded accelerating structure via the dielectric wake-field acceleration mechanism. Fields produced by a first, drive, beam were used to accelerate a second, witness, electron bunch which followed the driving bunch at an adjustable distance. The energy gain of the witness bunch as a function of its separation from the drive bunch is a direct measurement of the wake potential. We also present wakefield mapping results for THz quartz structures. In this case decelerating wake inside the bunch is inferred from the drive beam energy modulation.

WEPPP044

Advances in CVD Diamond for Accelerator Applications

wakefield, plasma, laser, acceleration

2819

A. Kanareykin, S.P. Antipov, J.E. Butler, C.-J. Jing, S.S. Zuo
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: Work supported by the SBIR program of the US Department of Energy.
Diamond is being evaluated as a dielectric material for dielectric loaded accelerating structures. It has a very low microwave loss tangent, high thermal conductivity, and supports high RF breakdown fields. We report on progress in fabricating chemical vapor deposited (CVD) diamond materials for cylindrical dielectric structures for use in wakefield particle accelerators. Tubes with inner diameters of 3 and 5 mm have been grown from polycrystalline CVD diamond on mandrels using microwave plasma assisted CVD. The material has been laser trimmed to the desired thicknesses and lengths. In addition, structures with smaller inner diameters (ca. 0.3 mm) have been laser machined from blocks of single crystal diamond grown by CVD. Rectangular (planar) dielectric structures have been constructed from plates of polished CVD diamond. Wakefields in these structures have been studied at the Brookhaven ATF.

WEPPP045

Beam-breakup Analysis for an Annular Cherenkov High Gradient Wakefield Accelerator

wakefield, simulation, vacuum, collider

2822

A. Kanareykin, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
A. Altmark
LETI, Saint-Petersburg, Russia

Funding: This work is supported by the SBIR Program of the US Department of Energy.
A complete analytical solution for Cherenkov wakefields generated by an azimuthally asymmetric annular beam propagating in a coaxial two-channel dielectric structure is presented. The transformer ratio of the annular beam Cherenkov wakefield accelerator initially proposed by R. Keinigs, M. Jones* is dramatically increased in comparison to a collinear cylindrical wakefield accelerating structure. A particle-Green's function beam dynamics code BBU-3000** to study beam breakup effects has been upgraded to incorporate annular drive beams and coaxial dielectric wakefield accelerating structures*. Beam dynamics simulations of the annular drive beam with asymmetric charge distributions have been carried out to determine the sensitivity of this method to beam imperfections in GHz and THz frequency ranges.
*R. Keinigs, M. Jones, Proc. 7th Int. Conf. High-Power Part. Beams, Beams’88, Karlsruhe, Germany, 864 (1988).
**P. Schoessow et al., AIP Conference Proceedings 1299, 262 (2010).

WEPPP052

Self-modulation of Long Particle Bunches in Plasmas at SLAC

plasma, wakefield, simulation, positron

2831

P. Muggli
MPI, Muenchen, Germany
Y. Fang
USC, Los Angeles, California, USA
M.J. Hogan
SLAC, Menlo Park, California, USA
W.B. Mori
UCLA, Los Angeles, California, USA
L.O. Silva, J. Vieira
IPFN, Lisbon, Portugal

The transverse self-modulation (SM) of ultra-relativistic, long particle bunches can lead to the generation of large amplitude wakefields*. In this work we show that the physics of SM could be investigated with the long electron and positron bunches available at SLAC**. The propagation of SLAC electron and positron bunches in 1 meter plasmas was modeled with OSIRIS. 3D simulations reveal that hosing may limit SM, but that shaped bunches with a hard-cut front ensure that saturation of SM can be reached. Cylindrically symmetric simulations show that the blowout regime can be achieved using these shaped bunches. Accelerating gradients in excess of 20 GeV/m are generated, and up to 10 GeV energy gain and loss are observed in the simulations at the 1% charge level after one meter of plasma. Because the blowout regime is reached, positron driven wakes lead to accelerating gradients that can be less than half than those of electrons. Simulations results outlining the SM results expected with the SLAC-FACET beam parameters will be presented.
* N. Kumar et al., Phys. Rev. Lett. 10⁴, 255003 (2010).
** J. Vieira et al., submitted (2011).

WEPPP056

Positron PWFA Simulations for FACET

plasma, positron, simulation, focusing

2834

S.J. Gessner, E. Adli, S. Corde, R.J. England, J.T. Frederico, M.J. Hogan, S.Z. Li, M.D. Litos, T.O. Raubenheimer, D.R. Walz, Z. Wu
SLAC, Menlo Park, California, USA
W. An, W.B. Mori
UCLA, Los Angeles, California, USA

Funding: Work supported [optional: in part] by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
When a positron beam enters a plasma, plasma electrons are drawn in toward the beam axis, creating a region of extremely large charge density with complicated, nonlinear fields. Few analytic solutions exist to describe these fields, and this necessitates the use of simulations to model positron beam and plasma interactions. This presentation should cover recent work on positron PWFA simulations using the QuickPIC* particle-in-cell code. I will discuss the computational challenges associated with positron PWFA and specific applications of the simulations for future experimental tests at the FACET user facility at SLAC.
* C. Huang et al., "QuickPIC: A highly efficient particle-in-cell code for modeling wakefield acceleration in plasmas," J. Comp. Phys. 217, 658 (2006).

WEPPP059

First Measurements with Multibunch Feedback Systems at the Fast Ramping Stretcher Ring ELSA

feedback, kicker, damping, cavity

2840

M. Schedler, F. Frommberger, N. Heurich, W. Hillert, A. Roth, R. Zimmermann
ELSA, Bonn, Germany

Funding: Supported by German Research Foundation through SFB/TR 16.
At the Electron Stretcher Facility ELSA of Bonn University, an upgrade of the maximum stored beam current from 20 mA to 200 mA is planned. The storage ring operates applying a fast energy ramp of 4 GeV/s from 1.2 GeV to 3.5 GeV. The intended upgrade is mainly limited due to the excitation of multibunch instabilities. As a countermeasure, we succesfully commissioned state-of-the-art bunch by bunch feedback systems in the longitudinal and the two transverse dimensions. First results concerning the commissioning of the systems as well as the operation during the fast energy ramp will be presented. In particular, the performance while controlling the motion of every single bunch, especially in controlled bunch cleaning, will be discussed.

WEPPP065

Status of the SSRF Fast Orbit Feedback System

feedback, controls, storage-ring, insertion

2855

B.C. Jiang, J. Hou, C.X. Yin, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

The fast orbit feedback system with bandwidth up to 100Hz is under commissioning at SSRF. The main purposes of the system are to suppress the short term orbit stability under sub-micron level and to compensate the orbit distortions caused by changing gaps of the insertion devices. The layout of the system is described and the preliminary commissioning results are given out in this paper.

WEPPP084

Weighted SVD Algorithm for Close-Orbit Correction and 10 Hz Feedback in RHIC

feedback, proton, closed-orbit, ion

2906

C. Liu, R.L. Hulsart, A. Marusic, R.J. Michnoff, M.G. Minty, V. Ptitsyn
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Measurements of the beam position along an accelerator are typically treated equally using standard SVD-based orbit correction algorithms so distributing the residual errors, modulo the local beta function, equally at the measurement locations. However, sometimes a more stable orbit at select locations is desirable. In this paper, we introduce an algorithm for weighting the beam position measurements to achieve a more stable local orbit. The results of its application to close-orbit correction and 10-Hz orbit feedback will be shown and analyzed.

WEPPR005

Study of Electron Cloud Instability in Fermilab Main Injector

injection, simulation, proton, damping

2943

K. Ohmi
KEK, Ibaraki, Japan
R.M. Zwaska
Fermilab, Batavia, USA

Electron cloud has been observed in Fermilab main injector. Electron signal is enhanced near the transition. The slippage factor which suppress instabilities approach to zero at the transition. Instabilities must be most serious near the transition. The instability caused by the electron cloud is an important issue for high intensity operation and the future toward Project-X. Simulations of electron cloud instability near the transition is presented.

WEPPR010

Comparison between Electron Cloud Build-Up Measurements and Simulations at the CERN PS

simulation, pick-up, extraction, vacuum

2955

G. Iadarola
Naples University Federico II, Science and Technology Pole, Napoli, Italy
F. Caspers, S.S. Gilardoni, G. Iadarola, E. Mahner, G. Rumolo, C. Yin Vallgren
CERN, Geneva, Switzerland

The build up of an Electron Cloud (EC) has been observed at the CERN Proton Synchrotron (PS) during the last stages of the LHC high intensity beam preparation, especially after the bunch shortening before extraction. A dedicated EC experiment, equipped with two button pick-ups, a pressure gauge, a clearing electrode, and a small dipole magnet, is available in one of the straight sections of the machine. A measurement campaign has been carried out in order to scan the EC build-up of LHC-type beams with different bunch spacing, bunch intensity, and bunch length. Such information, combined with the results from build up simulations, is of relevance for the characterization in terms of Secondary Emission Yield (SEY) of the chamber inner surface. The interest is twofold: this will enable us to predict the EC build up distribution in the PS for higher intensity beams in the frame of the upgrade program, and it will provide validation of the EC simulation models and codes.

WEPPR013

Design of an Electrostatic Extraction Section for the University of Maryland Electron Ring

extraction, simulation, emittance, lattice

2964

K.J. Ruisard
Rutgers University, The State University of New Jersey, Piscataway, New Jersey, USA
B.L. Beaudoin, I. Haber, R.A. Kishek, T.W. Koeth
UMD, College Park, Maryland, USA

Funding: This work is supported by the US Dept. of Energy Office of High Energy Physics.
The University of Maryland Electron Ring (UMER) is a 11.5 meter circumference, 10 keV, electron storage ring dedicated to the study of the physics space-charge-dominated beams transported over long path lengths. The intensity of the space charge in UMER can be varied by aperturing the injected beam current from 0.6 mA to 100 mA. Recently, the electron beam has been transported over one thousand turns. To fully characterize the transverse and longitudinal evolution of the beam on a turn-by-turn basis, extraction and transport to a diagnostic station is required. We present the design of a pulsed electric extraction system that satisfies the challenging constraint of fitting the hardware within the dense magnet lattice. The extraction system must universally accommodate the range beam intensities and minimize any disruption to the circulating beam

WEPPR014

Recovering Measured Dynamics from a DC Circulating Space-Charge-Dominated Storage Ring

background, space-charge, diagnostics, storage-ring

2967

W.D. Stem, B.L. Beaudoin, I. Haber, T.W. Koeth
UMD, College Park, Maryland, USA

Funding: This work is supported by the US Dept. of Energy Offices of High Energy Physics and Fusion Energy Sciences, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office.
Space-charge is increasingly significant at high beam intensities such as in FEL injectors and heavy ion inertial fusion drivers, where it dominates the beam dynamics. The University of Maryland Electron Ring (UMER) is a high intensity circular machine that is dedicated to the study of long path length space-charge-dominated beam physics on a small scale. Over multiple turns, longitudinal space charge effects cause the tail and head of an electron bunch to expand and interpenetrate, eventually resulting in a “DC beam”. This leads to complications when trying to measure the beam with UMER’s AC coupled diagnostics. Three techniques are developed to recover the information within the beam. Two “knockout” techniques implement invasive pulsed electric kicks to the beam in combination with either a fluorescent imaging screen or a current monitor. A third technique based on integration of the wall-current signal provides a non-invasive method to study the DC beam dynamics. Experimental results from all three methods are compared. The DC beam profile can then be studied over long trajectories and the existence of any loss mechanisms can be determined.

WEPPR015

Intrabeam Scattering Studies at CesrTA

emittance, scattering, positron, lattice

2970

M. P. Ehrlichman
Cornell University, Ithaca, New York, USA
F. Antoniou, Y. Papaphilippou
CERN, Geneva, Switzerland
W. Hartung, M.A. Palmer, D.P. Peterson, N.T. Rider, D. L. Rubin, J.P. Shanks, C.R. Strohman, S. Wang
CLASSE, Ithaca, New York, USA
R. Holtzapple
CalPoly, San Luis Obispo, California, USA

Funding: NSF Award (PHY-0734867) NSF Award (PHY-1002467) Japan/US Cooperation Program Education and lifelong learning, co-financed by Greece and the European Union
Intrabeam scattering dilutes the emittance of low energy, low emittance rings. Because CesrTA can be operated at low energies with low transverse emittances and high bunch intensity, it is an ideal laboratory for the study of IBS effects. Furthermore, CesrTA is instrumented for accurate beam size measurements in all three dimensions, providing the possibility of a complete determination of the intensity dependence of emittances. Models based on classical IBS theories and multi-particle simulations are used to estimate the effect of IBS at CesrTA at different beam emittances, intensities and energies. The first measurements from machine studies at CesrTA are presented.

WEPPR016

Potential for Luminosity Improvement for Low-energy RHIC Operation

luminosity, space-charge, ion, emittance

2973

A.V. Fedotov
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
At the Brookhaven National Laboratory, a physics program, motivated by the search of the QCD phase transition critical point, requires operation of the Relativistic Heavy Ion Collider (RHIC) with heavy ions at very low beam energies corresponding to 2.5-20 GeV/n. Several physics runs were already successfully performed at these low energies. However, the luminosity is very low at lowest energies of interest (< 10 GeV/n) limited by the intra-beam scattering and space-charge, as well as by machine nonlinearities. At these low energies, electron cooling is very effective in counteracting luminosity degradation due to the IBS, while it is less effective against other limitations. Overall potential luminosity improvement for low-energy RHIC operation from cooling is summarized for various energies, taking into account all these limitations as well as beam lifetime measured during the low-energy RHIC runs. We also explore a possibility of further luminosity improvement under the space-charge limitation.

WEPPR017

Wake Fields Effects for the eRHIC Project

cavity, wakefield, vacuum, beam-transport

2976

A.V. Fedotov, S.A. Belomestnykh, D. Kayran, V. Litvinenko, V. Ptitsyn
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
An Energy Recovery Linac (ERL) with a high peak electron bunch current is proposed for the Electron-Ion collider (eRHIC) project at the Brookhaven National Laboratory. The present design is based on the multi-pass electron beam transport in existing tunnel of the Relativistic Heavy Ion Collider (RHIC). As a result of a high peak current and a very long beam transport, consideration of various collective beam dynamics effects becomes important. Here we summarize effects of the coherent synchrotron radiation, resistive wall, accelerating cavities and wall roughness on the resulting energy spread and energy loss for several scenarios of the eRHIC project, including results for different electron distributions. A possible correction scheme of accumulated correlated energy spread is also presented.

WEPPR031

Injector Beam Dynamics for a High-repetition Rate 4th-generation Light Source

emittance, space-charge, gun, linac

3000

C. F. Papadopoulos, J.N. Corlett, P. Emma, D. Filippetto, G. Penn, J. Qiang, M.W. Reinsch, F. Sannibale, C. Steier, M. Venturini, R.P. Wells
LBNL, Berkeley, California, USA

Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
We report on the beam dynamics studies and optimization methods for a high-repetition (1 MHz) photoinjector based on a VHF normal conducting electron source. The simultaneous goals of beam compression and preservation of 6-dimensional beam brightness have to be achieved in the injector, in order to accommodate a linac driven FEL light source. For this, a parallel, multiobjective optimization algorithm is used. We discuss the relative merits of different injector design points, as well as the constraints imposed on the beam dynamics by technical considerations such as the high repetition rate.

WEPPR035

Optimization of Drive-bunch Current Profile for Enhanced Transformer Ratio in Beam-driven Acceleration Techniques

acceleration, simulation, vacuum, plasma

3012

F. Lemery, D. Mihalcea, P. Piot, C.R. Prokop
Northern Illinois University, DeKalb, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
In recent years, wakefield acceleration has gained attention due to its high acceleration gradients and cost effectiveness. In beam-driven wakefield acceleration, a critical parameter to optimize is the transformer ratio. It has been shown that current shaping of electron beams allows for enhanced (>2) transformer ratios. In this paper we present the optimization of the pulse shape of the drive bunch for dielectric-wakefield acceleration. We also explore practical techniques capable of tailoring current profiles into these optimal shapes.

WEPPR041

Design of a Compact Linear Accelerator for the Ultrafast Electron Diffraction Facility

gun, linac, space-charge, emittance

3027

M. Mamtimin, A.W. Hunt, Y. Kim, D.P. Wells
IAC, Pocatello, IDAHO, USA

Ultrafast Electron Diffraction (UED) is a powerful tool to find 3-dimensional structures and dynamical transitions of chemical or biological samples with a femtosecond-range temporal resolution and an angstrom-range spatial resolution. Due to the columbic field of electrons, UED can provide a higher cross section and a higher time resolution than those of the ultrafast photon diffraction with X-ray Free Electron Lasers (XFELs). In this paper, we describe the design concepts and ASTRA simulation results of a compact linac for an UED facility.

WEPPR046

THz Bursting Thresholds Measured at the Metrology Light Source

storage-ring, synchrotron, vacuum, octupole

3030

M. Ries, J. Feikes, P.O. Schmid, G. Wüstefeld
HZB, Berlin, Germany
A. Hoehl
PTB, Berlin, Germany

At the Metrology Light Source (MLS) * of the Physikalisch-Technische Bundesanstalt (PTB) the bunch length can be varied by more than two orders of magnitude **. The bunch length manipulation is achieved by varying different machine parameters, such as rf-voltage amplitude up to 500 kV and the momentum compaction factor over three orders of magnitude. The subject of this article is the measurement of THz bursting thresholds at the MLS for different bunch lengths.
* B. Beckhoff et al., Phys. Status Solidi B 246, p. 1415 (2009)
** J. Feikes et al., Phys. Rev. ST Accel. Beams 14, 030705 (2011).

WEPPR047

The Effect of Non-Zero Closed Orbit on Electron-Cloud Pinch Dynamics

quadrupole, proton, dipole, simulation

3033

G. Franchetti
GSI, Darmstadt, Germany
F. Zimmermann
CERN, Geneva, Switzerland

A study on the pinch dynamics of electron cloud during a bunch passage under the effect of a single arbitrary-order multipole was presented at IPAC2011. The complexity of the pinch pattern is directly related to the order of the multipolar field. However, in a realistic situation, the proton beam will not be located in the center of the vacuum chamber. If the beam is offset a new pinch regime is encountered, where feed-down effects and asymmetry of pinch density render the dynamics more challenging. In this paper we discuss the pinch dynamics with orbit offset, including the resulting orbit variation along a bunch, and address their relevance for the incoherent effect of the electron cloud.

WEPPR049

The Impact of Fill Patterns on the Fast Ion Instability in the ILC Damping Ring

ion, damping, emittance, feedback

3036

G.X. Xia
MPI-P, München, Germany

The ions produced via collisional ionization of the residual gas molecules in vacuum pipe with the circulating electron beam have deleterious effect on the beam properties and may become a limiting factor in the machine’s performance. In this paper, the various beam fill patterns are investigated and their effects on the fast ion instability are discussed. The simulations show that an optimal fill pattern can reduce growth rate of the fast ion instability significantly.

WEPPR050

Future Colliders Based on a Modulated Proton Bunch Driven Plasma Wakefield Acceleration

plasma, proton, collider, wakefield

3039

G.X. Xia, A. Caldwell
MPI-P, München, Germany
P. Muggli
MPI, Muenchen, Germany

Recent simulation shows that a self-modulated high energy proton bunch can excite large amplitude plasma wakefields and accelerate an external electron bunch to higher energies*. Based on this scheme, future colliders, either an electron-positron linear collider (e⁺e⁻ collider) or an electron-hadron collider (e.g. LHeC) can be conceived. In this paper, we discuss some key design issues for an e⁺e⁻ collider and a high energy LHeC collider, based on the existing infrastructure of the CERN accelerator complex.
* A. Caldwell, K. Lotov, Plasma wakefield acceleration with a modulated proton bunch, arXiv: 1105.1292 (2011).

WEPPR057

On the Single Bunch Longitudinal Collective Effects in BEPCII

impedance, storage-ring, collective-effects, controls

3054

D. Wang, Z. Duan, J. Gao, Y. Li, L. Wang, L. Wang, N. Wang
IHEP, Beijing, People's Republic of China

Funding: National Natural Science Foundation of China,project 11175192.
In order to study the single bunch longitudinal instability in BEPCII, experiments on the bunch lengthening phenomenon were made. By analyzing the experimental data based on the Gao’s theory, the longitudinal loss factor for the bunch are obtained. Also, the total wake potential and the inductance of the machine are estimated.

WEPPR059

The Simulation of Ion Cloud Build-up in Electron Storage Ring

ion, simulation, space-charge, storage-ring

3060

X.L. Yu, W. Li, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

In electron storage rings, positive ions are created by the ionization of the residual gas. Three main collision types including elastic collision, excitation collision and ionization collision are considered in this paper. In order to calculate the probability of the gas ionization using DSMC method, the total cross section, total inelastic cross section, elastic cross section, excitation cross section and ionization cross section are deduced separately. Once ions are created，PIC is adopted to trace the ion，s motion under the combined action due to externally applied field and self-field. The purpose of all study is to present how ion cloud gets to equilibrium little by little.

WEPPR060

Short range wakefields in MAX IV and FERMI Linac

wakefield, linac, cavity, dipole

3063

O. Karlberg, F. Curbis, S. Thorin, S. Werin
MAX-lab, Lund, Sweden
P. Craievich, E. Ferrari, G. Penco
ELETTRA, Basovizza, Italy

Ultra-short electron pulses suffer from transverse wake fields resulting in a degradation of the beam quality. Since transverse emittance is a crucial parameter for possible FEL drivers, a careful characterization of wakefields is necessary in the design and commissioning phase of a high-brightness linear accelerator. In this paper we investigate the effect of short-range transverse wakefields in the MAXIV linac in various compression modes. Estimations of the wake potentials have been done with 3D modeling of the accelerating structures as well as with analytical models.

WEPPR068

Mitigation of Electron Cloud Instabilities in the LHC Using Sextupoles and Octupoles

octupole, sextupole, damping, resonance

3084

K.S.B. Li, G. Rumolo
CERN, Geneva, Switzerland

Coherent electron cloud instabilities pose a serious limitation for luminosity upgrades in the Large Hadron Collider (LHC) at CERN. In particular, when bunch spacings reach below 50 ns, electron cloud formation is enhanced which in turn drives beam instabilities. The beam can be stabilised by shifting the tune and by increasing the tune spread using sextupoles or octupoles, respectively. The resulting values for the chromaticity and the detuning parameters must be selected with care, however, in order not to run into head-tail instabilities or to considerably reduce the dynamic aperture. A simulation study has been launched to estimate the parameters necessary for stabilisation of the beam under the influence of electron clouds.

WEPPR075

Monitoring the Progress of LHC Electron-Cloud Scrubbing by Benchmarking Simulations and Pressure-Rise Observations

simulation, vacuum, injection, dipole

3105

C.O. Domínguez, G. Arduini, E. Métral, G. Rumolo, F. Zimmermann
CERN, Geneva, Switzerland
G. Iadarola
Naples University Federico II, Science and Technology Pole, Napoli, Italy

Electron bombardment of a surface has been proven to reduce drastically the secondary electron yield of a material. This technique, known as scrubbing, is the ultimate solution to decrease the negative effects of an electron cloud build-up in any particle accelerator operating with intense beams. Its effectiveness has been already observed at the LHC. Since at the LHC no in-situ secondary-yield measurements are available, it has been necessary to develop a method to infer different key beam-pipe surface parameters by benchmarking simulations and pressure-rise observations. The method developed allows us to monitor the scrubbing process in order to decide on the most appropriate strategies for machine operation. In this paper we present the latest results of applying this method to the LHC in the fall of 2011 and early 2012, including data for the nominal bunch spacing of 25 ns.

WEPPR076

Positron Options for the Linac-ring LHeC

target, positron, emittance, laser

3108

F. Zimmermann, O.S. Brüning, Y. Papaphilippou, D. Schulte, P. Sievers
CERN, Geneva, Switzerland
H.-H. Braun
Paul Scherrer Institut, Villigen, Switzerland
E.V. Bulyak
NSC/KIPT, Kharkov, Ukraine
M. Klein
The University of Liverpool, Liverpool, United Kingdom
L. Rinolfi
JUAS, Archamps, France
A. Variola, Z.F. Zomer
LAL, Orsay, France
V. Yakimenko
BNL, Upton, Long Island, New York, USA

The full physics program of a future Large Hadron electron Collider (LHeC) requires both pe⁺ and pe- collisions. For a pulsed 140-GeV or an ERL-based 60-GeV Linac-Ring LHeC this implies a challenging rate of, respectively, about 1.8·10¹⁵ or 4.4·10¹⁶ e+/s at the collision point, which is about 300 or 7000 times the past SLC rate. We consider providing this e⁺ rate through a combination of measures: (1) Reducing the required production rate from the e⁺ target through colliding e⁺ (and the LHC protons) several times before deceleration, by reusing the e⁺ over several acceleration/deceleration cycles, and by cooling them, e.g., with a compact tri-ring scheme or a conventional damping ring in the SPS tunnel. (2) Using an advanced target, e.g., W-granules, rotating wheel, sliced-rod converter, or liquid metal jet, for converting gamma rays to e+. (3) Selecting the most powerful of several proposed gamma sources, namely Compton ERL, Compton storage ring, coherent pair production in a strong laser, or high-field undulator radiation from the high-energy lepton beam. We describe the various concepts, present example parameters, estimate the electrical power required, and mention open questions.

WEPPR079

Observations of Microbunching Instabilities from a THz Port at Diamond Light Source

radiation, storage-ring, synchrotron, optics

3114

W. Shields, G.E. Boorman, V. Karataev, A. Lyapin
JAI, Egham, Surrey, United Kingdom
R. Bartolini, A.F.D. Morgan, G. Rehm
Diamond, Oxfordshire, United Kingdom

Diamond Light source is a third generation synchrotron facility dedicated to producing radiation of outstanding brightness. Above a threshold current, the electron bunches are susceptible to the phenomenon known as the microbunching instability. This instability is characterised by the onset of radiation bursts, the wavelength of which is around one order of magnitude shorter than the bunch length. Near threshold, the bursting occurs quasi-‐periodically, however at higher currents, the bursting appears randomly. The high frequencies involved in these emissions make detection and analysis challenging. A port specifically for the investigation of mm wave emissions has recently been built at Diamond. Ultra fast Schottky Barrier Diode detectors have been installed to obtain data for only a small fraction of the bunch revolution time in an updated data acquisition system. The threshold current and subsequent evolution of the instability have been investigated.

WEPPR087

Dependence of Beam Instabilities Caused by Electron Clouds at CesrTA Due to Variations in Chromaticity, Bunch Current and Train Length

betatron, feedback, emittance, positron

3135

M.G. Billing, G. Dugan, M.J. Forster, D.L. Kreinick, R.E. Meller, M.A. Palmer, G. Ramirez, M.C. Rendina, N.T. Rider, J.P. Sikora, K.G. Sonnad, H.A. Williams
CLASSE, Ithaca, New York, USA
J.Y. Chu
CMU, Pittsburgh, Pennsylvania, USA
J.W. Flanagan
KEK, Ibaraki, Japan
R. Holtzapple, M. Randazzo
CalPoly, San Luis Obispo, California, USA

Funding: Work supported by DOE Award DE-FC02-08ER41538, NSF Award PHY-0734867 and the Lepton Collider R&D Coop Agreement: NSF Award PHY-1002467.
Electron cloud-induced beam dynamics is being studied at CESRTA under various conditions. These measurements detect the the coherent self-excited spectrum for each bunch within a train and bunch-by-bunch beam size. In the position spectrum coherent betatron dipole and head-tail motion is detectable for each individual bunch within the train with a sensitivity for the motion of 1.1 (2) microns-rms in the vertical (horizontal) direction for a 1 mA bunch current. These techniques are utilized to study the electron cloud-related interactions, which cause the growth of coherent motion and beam size along the train. We report on the observations and results from studies of the instability growth vs. changes in chromaticity, the current per bunch and the length of the train.

WEPPR088

Modeling and Simulation of Retarding Field Analyzers at CESRTA

dipole, simulation, vacuum, gun

3138

J.R. Calvey, J.A. Crittenden, G. Dugan, W. Hartung, J. Makita, M.A. Palmer
CLASSE, Ithaca, New York, USA
M.A. Furman, M. Venturini
LBNL, Berkeley, California, USA

Funding: Work supported by the US National Science Foundation (PHY-0734867 and PHY-1002467), and Department of Energy (DE-FC02-08ER41538).
Over the course of the CESRTA program at Cornell, Retarding Field Analyzers (RFAs) have been installed in drift, dipole, quadrupole, and wiggler field regions of the CESR storage ring. RFAs are used to measure the local electron cloud flux on the vacuum chamber wall. Through the use of a retarding grid and segmented collectors, they also provide information on the energy and transverse distribution of the cloud. Understanding these measurements on a quantitative level requires the use of cloud buildup simulation codes, adapted to include a detailed model of the structure of the RFA and its interaction with the cloud. The nature of this interaction depends strongly on the strength of the local magnetic field. We have developed models for RFAs in drift and dipole regions. The drift model has been cross-checked with bench measurements, and we have compared the RFA-adapted cloud buildup simulations with data. These comparisons have then been used to obtain best fit values for the photo-emission and secondary electron emission characteristics of some of the vacuum chamber materials and cloud mitigating coatings employed at CESRTA.

WEPPR089

Experimental Progress: Current Filamentation Instability Study

plasma, simulation, emittance, radiation

3141

B.A. Allen, P. Muggli
USC, Los Angeles, California, USA
M. Babzien, M.G. Fedurin, K. Kusche, V. Yakimenko
BNL, Upton, Long Island, New York, USA
C. Huang
LANL, Los Alamos, New Mexico, USA
J.L. Martins, L.O. Silva
IPFN, Lisbon, Portugal
W.B. Mori
UCLA, Los Angeles, California, USA

Funding: Work supported by: National Science Foundation and US Department of Energy.
Current Filamentation Instability, CFI, is of central importance for the propagation of relativistic electron beams in plasmas. CFI has potential relevance to astrophysics, magnetic field and radiation generation in the afterglow of gamma ray bursts, and inertial confinement fusion, energy transport in the fast-igniter concept. An experimental study of this instability is underway at the Accelerator Test Facility, ATF, at Brookhaven National Laboratory with the 60MeV electron beam and centimeter length capillary discharge plasma. The experimental program includes the systematic study and characterization of the instability as a function of beam (charge, transverse and longitudinal profile) and plasma (plasma density) parameters. Specifically, the transverse beam profile is measured directly at the plasma exit using optical transition radiation from a thin gold-coated silicon window. Experimental results show the reduction of the beam transverse size and the appearance of multiple (1-4) filaments and are a function of the plasma density. We will present simulation and experimental results, provide discussion of these results and outline next steps in the experiment.

WEPPR091

Multi-Particle Simulation Codes Implementation to Include Models of a Novel Single-bunch Feedback System and Intra-beam Scattering

feedback, emittance, simulation, damping

3147

M.T.F. Pivi, A. Chao, C.H. Rivetta
SLAC, Menlo Park, California, USA
F. Antoniou, K.S.B. Li, Y. Papaphilippou
CERN, Geneva, Switzerland
M. Boscolo, T. Demma
INFN/LNF, Frascati (Roma), Italy
K.G. Sonnad
CLASSE, Ithaca, New York, USA

Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP).
The beam tracking codes C-MAD and HEAD-TAIL have been enhanced to include a detailed model of a single-bunch feedback system. Such a system is under development to mitigate the electron cloud and the transverse mode coupling instability (TMCI) in the SPS and LHC at CERN. This paper presents the model of the feedback sub-systems: receiver, processing channel, filter, amplifier and kicker, which takes into account the frequency response, noise, mismatching and technological limits. With a realistic model of the hardware, it is possible to study the prototypes installed in the SPS and design a novel feedback system. The C-MAD code, which is parallel and optimized for speed, now also includes radiation damping and quantum excitation and a detailed model of Intra-Beam Scattering (IBS) based on the Zenkevich-Bolshakov algorithm, to investigate the IBS during damping and its effect on the beam distribution, especially the beam tails, that analytical methods cannot investigate. Intra-beam scattering is a limiting factor for ultra-low emittance rings such as CLIC and Super-B.

WEPPR093

Impedance Budget for Crab Cavity in MEIC Electron Ring

impedance, cavity, collider, ion

3153

S. Ahmed, G.A. Krafft, B.C. Yunn
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The Medium Energy Electron-Ion Collider (MEIC) at Jefferson Lab has been envisioned as a first stage high energy particle accelerator beyond the 12 GeV upgrade of CEBAF. The estimate of impedance budget is important from the view point of beam stability and matching with other accelerator components driving currents. The detailed study of impedance budget for electron ring has been performed by considering the current design parameters of the e-ring. A comprehensive picture of the calculations involved in this study has been illustrated in the paper.

WEPPR094

Large Volume Resonant Microwave Discharge for Plasma Cleaning of a CEBAF 5-Cell Srf Cavity

cavity, plasma, coupling, SRF

3156

S. Ahmed, K. Macha, J.D. Mammosser
JLAB, Newport News, Virginia, USA
M. Nikolić, S. Popović, J. Upadhyay, L. Vušković
ODU, Norfolk, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. The U.S.
We report preliminary results on plasma generation in a 5-cell CEBAF SRF cavity for the application of cavity interior surface cleaning. CEBAF currently has ~300 of these five cell cavities installed in the JLab accelerator which are mostly limited by cavity surface contamination. The development of an in-situ cavity surface cleaning method utilizing a resonant microwave discharge could lead to significant performance improvement. This microwave discharge is currently being used for set of plasma cleaning procedures targeted to the removal of various organic, metal and metal oxide impurities. These contaminants are responsible for the increase of surface resistance and the reduction of RF performance in installed cavities. CEBAF five cell cavity volume is ~ 0.5 m2, which places the discharge in the category of large-volume plasmas. Our preliminary study includes microwave breakdown and optical spectroscopy, which was used to define the operating pressure range and the rate of removal of organic impurities.

WEPPR095

Radial Eigenmodes for a Toroidal Waveguide with Rectangular Cross Section

impedance, resonance, wakefield, synchrotron

3159

R. Li
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
In applying mode expansion to solve the CSR impedance for a section of toroidal vacuum chamber with rectangular cross section, we identify the eigenvalue problem for the radial eigenmodes which is different from that for cylindrical structures. In this paper, we present the general expressions of the radial eigenmodes, and discuss the properties of the eigenvalues on the basis of the Sturm-Liouville theory.

WEPPR099

Shielding of a Hadron in a Finite e-Beam

plasma, shielding, hadron, linac

3171

A. Elizarov, V. Litvinenko, G. Wang
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The thorough study of coherent electron cooling, the modern cooling technique capable to deal with accelerators operating in the range of few TeVs*, rises many interesting questions. One of them is a shielding dynamics of a hadron in an electron beam. Now this effect is computed analytically in an infinite beam approximation**. Many effects are drastically different in finite and infinite plasmas. Here we propose a method to compute the dynamical shielding effect in a finite cylindrical plasma - the realistic model of an electron beam in accelerators.
* V. N. Litvinenko, Y. S. Derbenev, Phys. Rev. Lett. 10², 114801 (2009).
** G. Wang, M. Blaskiewicz, Phys. Rev. E 78, 026413 (2008).

THXA01

Producing Medical Isotopes using X-rays

linac, target, neutron, extraction

3177

M.S. de Jong
CLS, Saskatoon, Saskatchewan, Canada

Funding: Natural Resources Canada Non-reactor-based Isotope Supply Program Contribution Agreement Saskatchewan Crown Investment Corporation Contribution Agreement
In recent years, there has been frequent shortages of Mo-99 and its daughter isotope, Tc-99m, which are the most heavily used medical diagnostic radio-isotopes. The Canadian Light Source is leading a project to demonstrate large-scale photo-neutron production of Mo-99 using a high-power 35 MeV electron linac as an alternative to production of Mo-99 from fission of highly enriched U-235 in research reactors. This talk will present the results that have been obtained to date and discuss the commercial potential for this alternative production scheme.

Slides THXA01 [6.482 MB]

THYA02

Ultracompact Accelerator Technology for a Next-generation Gamma-Ray Source

gun, klystron, laser, photon

3190

R.A. Marsh, F. Albert, S.G. Anderson, C.P.J. Barty, D.J. Gibson, F.V. Hartemann, S.S.Q. Wu
LLNL, Livermore, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
This presentation will report on the technology choices and progress manufacturing and testing the injector and accelerator of the 250 MeV ultra-compact Compton Scattering X-ray Source under development at LLNL for homeland security applications.

Slides THYA02 [12.896 MB]

THXB01

Interaction of Muon Beam with Plasma Developed During Ionization Cooling

plasma, wakefield, simulation, collider

3200

S. Ahmed
JLAB, Newport News, Virginia, USA
K.B. Beard, T.J. Roberts
Muons, Inc, Batavia, USA
D.M. Kaplan, L.K. Spentzouris
Illinois Institute of Technology, Chicago, Illinois, USA

Muon collider has been envisioned as a future high energy lepton machine. High luminosity can be obtained by the ionization cooling – best suited for muons due to their short life time. In this cooling process, particles ionize material medium in which they lose momentum, thus the normalized emittance is reduced. The ionized medium is called plasma and the ionization density could increase due to the passage of multiple bunches through the material. This means that the incoming beams interact with plasma together with ionizing the medium used for cooling. It is, therefore, important to investigate the effects of background plasma on the incoming bunches. A comprehensive studies of muon beam propagation through plasma medium using EM particle-in-cell simulations. This computational study involves kinetic model, therefore, provides deep insight of the phenomena, which cannot be obtained by the conventional fluid model. The wakes excited by mu+ and mu- are different due to the beam polarity and depends on their relative densities. Externally applied axial magnetic field suppresses the wakes evolved during the interaction. The details of this study will be discussed in the paper.

Slides THXB01 [4.584 MB]

THYB02

Influence of Electron Beam Parameters on Coherent Electron Cooling

FEL, ion, acceleration, radiation

3213

G. Wang, Y. Hao
BNL, Upton, Long Island, New York, USA
V. Litvinenko
Stony Brook University, Stony Brook, USA
S.D. Webb
Tech-X, Boulder, Colorado, USA

Coherent electron cooling (CeC) is promising to revolutionize the cooling of high energy hadron beams. The intricate dynamics of the CeC depends both on the local density and energy distribution of the beam. This talk should present a rigorous analytical model of the 3D processes (including diffraction) in the modulator and the FEL and describe how the theory is applied to electron beams with inhomogeneous longitudinal density- and energy distributions in the process of CeC. The SPC would like you to describe the influence of electron beam energy and current variations along the bunch length.

Slides THYB02 [0.878 MB]

THAP01

Secondary-electron Emission from Hydrogen-terminated Diamond

vacuum, high-voltage, linac, simulation

3223

E. Wang, I. Ben-Zvi, T. Rao, Q. Wu
BNL, Upton, Long Island, New York, USA
D.A. Dimitrov
Tech-X, Boulder, Colorado, USA
T. Xin
Stony Brook University, Stony Brook, USA

Diamond amplifiers demonstrably are an electron source with the potential to support high-brightness, high-average-current emission into a vacuum. We recently developed a reliable hydrogenation procedure for the diamond amplifier. The systematic study of hydrogenation resulted in the reproducible fabrication of high gain diamond amplifier. Furthermore, we measured the emission probability of diamond amplifier as a function of the external field and modeled the process with resulting changes in the vacuum level due to the Schottky effect. We demonstrated that the decrease in the secondary electrons’ average emission gain was a function of the pulse width and related this to the trapping of electrons by the effective NEA surface. The findings from the model agree well with our experimental measurements. As an application of the model, the energy spread of secondary electrons inside the diamond was estimated from the measured emission.

Slides THAP01 [2.034 MB]

THEPPB002

High-Fidelity 3D Modulator Simulations of Coherent Electron Cooling Systems

ion, plasma, simulation, shielding

3231

G.I. Bell, D.L. Bruhwiler, I.V. Pogorelov, B.T. Schwartz
Tech-X, Boulder, Colorado, USA
Y. Hao, V. Litvinenko, G. Wang
BNL, Upton, Long Island, New York, USA

Funding: This work is supported by the US DOE Office of Science, Office of Nuclear Physics, grant numbers DE-SC0000835 and DE-FC02-07ER41499. Resources of NERSC were used under contract No. DE-AC02-05CH11231.
Next generation electron-hadron colliders will require effective cooling of high-energy, high-intensity hadron beams. Coherent electron cooling (CeC) can in principle cool relativistic hadron beams on orders-of-magnitude shorter time scales than other techniques*. The parallel VORPAL framework is used for 3D delta-f PIC simulations of anisotropic Debye shielding in a full longitudinal slice of the co-propagating electron beam, choosing parameters relevant to the proof-of-principle experiment under development at BNL. The transverse density conforms to an exponential Vlasov equilibrium for Gaussian velocities, with no longitudinal density variation. Comparison with 1D1V Vlasov/Poisson simulations shows good agreement in 1D. Parallel 3D simulations at NERSC show 3D effects for ions moving longitudinally and transversely. Simulation results are compared with the constant-density theory of Wang and Blaskiewicz**.
* V.N. Litvinenko and Y.S. Derbenev, Phys. Rev. Lett. 10², 114801 (2009).
** Wang and Blaskiewicz, Phys Rev E 78, 026413 (2008).

THEPPB008

Inverse Compton Scattering Experiment in a Bunch Train Regime Using Nonlinear Optical Cavity

laser, photon, cavity, linac

3245

A.Y. Murokh, R.B. Agustsson, S. Boucher, P. Frigola, T. Hodgetts, A.G. Ovodenko, M. Ruelas, R. Tikhoplav
RadiaBeam, Santa Monica, USA
M. Babzien, M.G. Fedurin, T.V. Shaftan, V. Yakimenko
BNL, Upton, Long Island, New York, USA
I. Jovanovic
Penn State University, University Park, Pennsylvania, USA

Inverse Compton Scattering (ICS) is a promising approach towards achieving high intensity, directional beams of quasi-monochromatic gammas, which could offer unique capabilities in research, medical and security applications. Practicality implementation of ICS sources, however, depends on the ability to achieve high peak brightness (~0.1-1.0 ICS photons per interacting electron), while increasing electron-laser beam interaction rate to about 10,000 cps. We discuss the results of the initial experimental work at the Accelerator Test Facility (ATF) at BNL to demonstrate ICS interaction in a pulse-train regime, using a novel laser recirculation scheme termed Recirculation Injection by Nonlinear Gating (RING). Initial experimental results and outlook are presented.

THEPPB009

The CRISP Project – Building Synergies between Research Infrastructures

neutron, ion, laser, ion-source

3248

P. Antici
INFN/LNF, Frascati (Roma), Italy

Recently, the European Commission granted 12 M€ for a project aiming at the implementation of common solutions in infrastructures on the ESFRI* roadmap in the fields of physics, astronomy and analytical sciences. The objective of this initiative is to generate synergies in the development of components of interest for several infrastructures and thus promote efficiency and optimisation in the use of resources. The project, called "CRISP (Cluster of Research Infrastructures for Synergies in Physics) and started October 2011, gathers many major European large-scale infrastructures (CERN, XFEL, ESRF, ESS, FAIR, ILL, SKA, SLHC, SPIRAL-2, ELI, EuroFEL, ILC-Higrade etc). The generated synergies will be crucial to stimulate scientific and technological progress and to respond to the rapidly evolving user community. A brief overview of the different activities that are part of the project will be given, presenting the innovative approach of crossing boundaries between scientific disciplines and thus generating synergies.
*ESFRI stands for European Strategy Forum on Research Infrastructures

THEPPB013

Progress in Modeling Arcs

plasma, cavity, ion, simulation

3260

J. Norem, Z. Insepov
ANL, Argonne, USA
S. Mahalingam, S.A. Veitzer
Tech-X, Boulder, Colorado, USA
A. Moretti
Fermilab, Batavia, USA
I. Morozov, G.E. Norman
JIHT RAS, Moscow, Russia

Funding: DOE Office of High Energy Physics.
We are continuing to extend and simplify our understanding of vacuum arcs. We believe that all the breakdown phenomena we see (with and without B fields) can be explained by: 1) fracture due to electrostatic forces at surface crack junctions, 2) the development of a unipolar arc driven by the cavity electric field, and 3) cooling, and cracking of the surface after the event is finished. Recent progress includes the evaluation of non-Debye sheaths using Molecular Dynamics, studies of sheath driven instabilities, a model of degradation of gradient limits in strong B fields, analysis of the variety of arcs that can occur in cavities and their damage and further studies of breakdown triggers.

THPPC002

Design and Construction of Turnkey Linacs as Injectors for Light Sources

beam-loading, simulation, linac, synchrotron

3272

A.S. Setty, D. Jousse
THALES, Colombes, France

Turnkey linacs were manufactured by Thales Communications & Security in order to inject electrons into boosters of SOLEIL*, ALBA and BESSY II synchrotrons. This paper will describe the beam dynamics tools and methods for the design and construction of those linacs. Cavities tuning and prebunching characterization methods will be given. Beam loading compensation and simulations will be explained. Specified and measured beam parameters will be compared.
* A. Setty et al, "Commissioning of the 100 MeV preinjector HELIOS for the SOLEIL synchrotron", EPAC 06, Scotland, Edinburgh, June 2006.

THPPC017

Study of Physical Processes of Acceleration of Electron Bunches with Extremal Density by Means of Stored Energy in Disk Loaded Waveguide Sections

linac, acceleration, radiation, electromagnetic-fields

3314

S. Proskin, A. Kulago
MEPhI, Moscow, Russia

This presentation should consider a new theoretical method of SHF power increasing in DWLG sections. Within the presentation physical processes of the acceleration of extremely charge densities in the sections of a DWLG by the stored energy are described. As a result optimum travelling wave DWLG is taken and a simulation of acceleration processes of 20 ns electron beams is conducted.

THPPC026

A Transverse Deflecting Cavity for the Measurement of Short Low Energy Bunches at EBTF

cavity, coupling, simulation, impedance

3335

G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
S.R. Buckley, P. Goudket, C. Hill, P.A. McIntosh, J.W. McKenzie, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The Electron Beam Test Facility (EBTF) at Daresbury Laboratory will deliver low energy (5/6 MeV) short bunches (~40 fs) to a number of industrial experimental stations and for scientific research. In order to measure the longitudinal profile of the bunch an S-band transverse deflecting cavity will be inserted into the beamline. A transverse kick of around 5 MV is required hence a 9 cell design has been chosen. The design of the transverse deflecting cavity has been influence by the competing demands of high RF efficiency and minimising the unwanted transverse kick at the entrance and exit of the cavity which cause the electrons to be displaced while traversing the cavity. This has led to a shortened end cell structure design to minimise the kick applied at the entrance and exit to the cavity. In order to minimise the impact of the input coupler a dummy waveguide has been placed on the opposing side of the cavity to minimise the monopole component of the RF fields in the coupling cell. The coupler is located at the central cell of the cavity to avoid exciting the nearby modes. Tracking of the beam is performed in GPT including space charge, due to the low energy of the electrons.

THPPC028

Kinetic Modeling of RF Breakdown in High-Pressure Gas-filled Cavities

simulation, plasma, cavity, vacuum

3341

D. Rose, C.H. Thoma
Voss Scientific, Albuquerque, New Mexico, USA
J.M. Byrd, D. Li
LBNL, Berkeley, California, USA
R.P. Johnson, M.L. Neubauer, R. Sah
Muons, Inc, Batavia, USA
A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, USA

Funding: Supported in part by USDOE STTR Grant DE-FG02-08ER86352
Recent studies have shown that high gradients can be achieved quickly in high-pressure gas-filled cavities without the need for long conditioning times, because the dense gas can dramatically reduce dark currents and multipacting. In this project we use this high pressure technique to suppress effects of residual vacuum and geometry found in evacuated cavities to isolate and study the role of the metallic surfaces in RF cavity breakdown as a function of radiofrequency and surface preparation. A series of experiments at 805 MHz using hydrogen fill pressures up to 0.01 g/cm³ of H2 have demonstrated high electric field gradients and scaling with the DC Paschen law limit, up to ~30 MV/m, depending on the choice of electrode material. For higher field stresses, the breakdown characteristics deviate from the Paschen law scaling. Fully-kinetic 0D collisional particle-in-cell (PIC) simulations give breakdown characteristics in H2 and H2/SF6 mixtures in good agreement with the 805 MHz experimental results below this field stress threshold. The impact of these results on gas-filled RF accelerating cavity design will be discussed.

THPPC033

Progress on a Cavity with Beryllium Walls for Muon Ionization Cooling Channel R&D

cavity, coupling, vacuum, simulation

3356

D.L. Bowring, A.J. DeMello, A.R. Lambert, D. Li, S.P. Virostek, M.S. Zisman
LBNL, Berkeley, California, USA
D.M. Kaplan
Illinois Institute of Technology, Chicago, Illinois, USA
R.B. Palmer
BNL, Upton, Long Island, New York, USA

Funding: Work supported by the Director, Office of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The Muon Accelerator Program (MAP) collaboration is working to develop an ionization cooling channel for future muon colliders. The ionization cooling channel requires the operation of high-gradient, normal-conducting RF cavities in solenoidal magnetic fields up to 5 T. However, experiments conducted at Fermilab's MuCool Test Area (MTA) show that increasing the solenoidal field strength reduces the maximum achievable cavity gradient. This gradient limit is characterized by an RF breakdown process that has caused significant damage to copper cavity interiors. The damage is likely caused by field-emitted electrons, focused by the solenoidal magnetic field onto small areas of the inner cavity surface. Local heating may then induce material fatigue and surface damage. Fabricating a cavity with beryllium walls would mitigate this damage due to beryllium's low density, low thermal expansion, and high electrical and thermal conductivity. This poster addresses the design and fabrication of a pillbox RF cavity with beryllium walls, in order to evaluate the performance of high-gradient cavities in strong magnetic fields.

THPPC042

Modified Magnicon for High-Gradient Accelerator R&D

cavity, gun, solenoid, cathode

3377

S.V. Shchelkunov, Y. Jiang, M.A. LaPointe
Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA
J.L. Hirshfield
Omega-P, Inc., New Haven, USA
V.P. Yakovlev
Fermilab, Batavia, USA

Funding: Research supported by the U.S. Department of Energy, Office of High Energy Physics
A self-consistent design is described of a modified 34.3 GHz magnicon amplifier with a TE311-mode output cavity, to replace the existing magnicon at Yale Beam Physics Lab Test Facility whose output cavity operates in the TM310 mode. The main goal for the new design is to achieve robust reliable operation. This is expected since tube performance – according to simulations – is largely insensitive to the magnitude of external dc magnetic fields, including imperfections in magnetic field profile; small changes in gun voltage and current; changes in electron beam radial size; and even poorly matched external circuitry. The new tube, as with its predecessor, is a third harmonic amplifier, with drive and deflection gain cavities near 11.424 GHz and output cavity at 34.272 GHz. The design calculations predict stable output of power of 20-27 MW at a 10 Hz repetition rate in pulses up to 1.3 μs long, with a low probability of breakdown in the output cavity because of low electric fields (less than 650 kV/cm).

THPPC043

Cold Test of an L-band, 2-Cell PWT Photoelectron

cavity, gun, simulation, vacuum

3380

Y. Luo, D. Yu
DULY Research Inc., Rancho Palos Verdes, California, USA
R. Andrews, T.N. Khabiboulline
Fermilab, Batavia, USA

Funding: DOE SBIR Grant No. DE-FG02-06ER84460
An L-band, 1+2/2-cell PWT gun with a coax coupler has been designed for high vacuum polarized electron source applications by DULY Research Inc. A cold test model was fabricated and is currently undergoing test at Fermilab, where the gun will eventually be hot tested. The aluminum cold test model includes an rf/ vacuum sieve, 2 disks, endplates, 6 supporting rods and a 6” CF flange, clamped together during testing. Fermilab made measurements for the cavity resonant frequency and axial field distribution using bead pull. To measure the resonant frequency of the cavity small diameter probes are placed through the vacuum sieve slot. A larger diameter probe can be used as an active tuner. This paper presents the results of the cold test and compares measurements with simulation results from 3D SLAC code Omega3p. The axial field distributions are in good agreement with each other. Frequency deviation is less than 0.5%, well within the experimental accuracy.

THPPC046

Normal Conducting Radio Frequency x-band Deflecting Cavity Fabrication and Validation

alignment, cavity, vacuum, linear-collider

3389

R.B. Agustsson, L. Faillace, A.Y. Murokh, S. Storms
RadiaBeam, Santa Monica, USA
D. Alesini
INFN/LNF, Frascati (Roma), Italy
V.A. Dolgashev
SLAC, Menlo Park, California, USA
J.B. Rosenzweig
UCLA, Los Angeles, California, USA
V. Yakimenko
BNL, Upton, Long Island, New York, USA

Funding: U.S. DOE SBIR grant DE-FG02-05ER84370
An X-band Traveling wave Deflector mode cavity (XTD) has been developed and fabricated at Radiabeam Technologies to perform longitudinal characterization of the sub-picosecond ultra-relativistic electron beams. The device is optimized for the 100 MeV electron beam parameters at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory, and is scalable to higher energies. An XTD is designed to operate at 11.424 GHz, and features short filling time, femtosecond resolution, and a small footprint. RF design, structure fabrication, cold testing results and commissioning plans are presented.

THPPC048

Innovative Low-Energy Ultra-Fast Electron Diffraction (UED) System

cathode, gun, vacuum, high-voltage

3395

L. Faillace, S. Boucher
RadiaBeam, Santa Monica, USA
P. Musumeci
UCLA, Los Angeles, California, USA

Funding: Work supported by DOE.
RadiaBeam, in collaboration with UCLA, is developing an innovative, inexpensive, low-energy ultra-fast electron diffraction (UED) system which allows us to reconstruct a single ultrafast event with a single pulse of electrons. Time resolved measurement of atomic motion is one of the frontiers of modern science, and advancements in this area will greatly improve our understanding of the basic processes in materials science, chemistry and biology. The high-frequency (GHz), high voltage, phase-locked RF field in the deflector allows temporal resolution as fine as 100 fs. In this paper, we show the complete design of a UED system based on this concept, including an optimized electron gun, a high-resolution RF deflector, and the post-interaction imaging system.

THPPC049

Progress on the MICE 201 MHz RF Cavity at LBNL

cavity, simulation, coupling, resonance

3398

T.H. Luo, D.J. Summers
UMiss, University, Mississippi, USA
A.J. DeMello, D. Li, S.P. Virostek, M.S. Zisman
LBNL, Berkeley, California, USA

The international Muon Ionization Cooling Experiment (MICE) aims at demonstrating transverse cooling of muon beams by ionization. The ionization cooling channel of MICE requires eight 201-MHz normal conducting RF cavities to compensate for the longitudinal beam energy loss in the cooling channel. In this paper, we present recent progresses on MICE RF cavity at LBNL, which includes electro-polishing, intended to improve the cavity performance in the presence of strong external magnetic field; low power RF measurements on resonant frequency and Q value of each cavity with a pair of curved- beryllium windows to terminate the cavity irises. Multipacting simulations are conducted using SLAC’s ACE-3P code to study the effects in the cavity and coupler regions with the influence by external magnetic field.

THPPC053

First Experience at ELBE with the New 1.3 GHz CWRF Power System Equipped with 10 kW GHz Solid State Amplifiers (SSPA)

klystron, cavity, radiation, linac

3407

H. Büttig, A. Arnold, A. Büchner, M. Justus, M. Kuntzsch, U. Lehnert, P. Michel, R. Schurig, G.S. Staats, J. Teichert
HZDR, Dresden, Germany

The superconducting CW- LINAC (1.3 GHz) of the radiation source ELBE is in permanent operation since May 2001/1/. During the winter shut-down 2011 - 1212 an upgrade program of ELBE was realized. One part of the program was to double the RF-power per cavity using two 10 kW Solid State Amplifiers in parallel per cavity. The poster gives an overview on the new RF-system and the experience gained within the first three months of operation.

THPPC055

Permanent Magnet Focusing System for Klystrons

klystron, permanent-magnet, cathode, focusing

3413

Y. Fuwa, Y. Iwashita, H. Tongu, S. Ushijima
Kyoto ICR, Uji, Kyoto, Japan
S. Fukuda
KEK, Ibaraki, Japan

The Distributed RF System (DRFS) for ILC requires thousands of klystrons. The failure rate of the power supply for solenoid focusing coil of each klystron may be harmful to a regular operation of the ILC. In order to eliminate the power supplies and the cooling system for the coils, a permanent magnet beam focusing system is under development. It will help to reduce the power consumption as well. In our design, a unidirectional magnetic field configuration is adopted to eliminate the stop bands that arise from the periodic permanent magnet configuration. Since the required magnetic field is not high in this case, inexpensive anisotropic ferrite magnets can be used instead of magnets containing rare earth materials. On the basis of a half scaled model fabricated to evaluate the mechanical design, a full scaled model will be ready soon. In order to prove its feasibility, a power test of the klystron for DRFS with this magnet system is planned. The result of magnetic field distribution measurement and the power test will be presented.

THPPC069

Design, Test and Implementation of New 201.25 MHz Power Amplifier for the LANSCE Linac

cathode, DTL, HOM, cavity

3446

J.T.M. Lyles, Z. Chen, J. Davis, A.C. Naranjo, D. Rees, G. M. Sandoval, Jr.
LANL, Los Alamos, New Mexico, USA
D. Baca, R.E. Bratton, R.D. Summers
Compa Industries, Inc., Los Alamos, New Mexico, USA
N.W. Brennan
Texas A&M University, College Station, Texas, USA

Funding: Work supported by the United States Department of Energy, National Nuclear Security Agency, under contract DE-AC52-06NA25396
A new 201.25 MHz final power amplifier (FPA) has been designed, fabricated, and tested at Los Alamos Neutron Science Center (LANSCE). The prototype FPA has produced 3 MW peak and 250 kW of mean power with 15 dB of power gain and over 60% efficiency. It has been tested for several thousand hours with a load. A Thales TH628 Diacrode® electron tube is key to the performance of the new amplifier. It is configured with a full wavelength output circuit, having the lower main tuner situated ¾λ from the central electron beam region in the tube and the upper slave tuner ¼λ from the same point. The FPA is designed with input and output transmission line cavity circuits, grid decoupling circuits, an adjustable output coupler, DC blocking and RF bypassing capacitors, HOM suppressors, and a cooling system. A pair of production amplifiers are planned to be power-combined for up to 3.6 MW peak power at high duty factor. Three of these combined amplifiers will be installed in place of the original 1968-vintage amplifiers to return LANSCE operation to 12% beam duty factor with higher peak current than presently possible.

THPPC071

The Use of a Solid State Analog Television Transmitter as a Superconducting Electron Gun Power Amplifier

cavity, gun, controls, LLRF

3452

J.G. Kulpin, K.J. Kleman
UW-Madison/SRC, Madison, Wisconsin, USA
R.A. Legg
JLAB, Newport News, Virginia, USA

Funding: The electron gun program is supported by DOE award DE-SC0005264, and the University of Wisconsin, Madison.
A solid state analog television transmitter designed for 200 MHz operation is being commissioned as a radio frequency power amplifier on the Wisconsin superconducting electron gun cavity. The amplifier consists of three separate radio frequency power combiner cabinets and one monitor and control cabinet. The transmitter employs rugged field effect transistors built into one kilowatt drawers that are individually hot swappable at maximum continuous power output. The total combined power of the transmitter system is 33 kW at 200 MHz, output through a standard coaxial transmission line. A low level radio frequency system is employed to digitally synthesize the 200 MHz signal and precisely control amplitude and phase.

THPPC074

High Frequency High Power RF Generation using a Relativistic Electron Beam

wakefield, extraction, damping, impedance

3458

C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
H. Chen, Y. Yang
TUB, Beijing, People's Republic of China
M.E. Conde, W. Gai, J.G. Power
ANL, Argonne, USA

High frequency, high power rf sources are required for many applications. Benefiting from the ~10 GW beam power provided by the high current linac at the Argonne Wakefield Accelerator facility, we propose to develop a series of high power rf sources based on the extraction of coherent Cherenkov radiation from the relativistic electron beam. The frequencies cover from C-band up to W-band with different structures. Simulations show that ~1 GW 20 ns rf pulse can be generated for an 11.7 GHz structure, ~400 MW for a 26 GHz structure, and ~14 MW for a 91 GHz structure.

THPPD037

Design Studies of a Dipole with Elliptical Aperture for the Muon Collider Storage Ring

dipole, collider, quadrupole, storage-ring

3590

M.L. Lopes, V. Kashikhin, J.C. Tompkins, A.V. Zlobin
Fermilab, Batavia, USA
R.B. Palmer
BNL, Upton, Long Island, New York, USA

Funding: Work supported partially by US-MAP and by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
The requirements and operating conditions for superconducting magnets used in a Muon Collider Storage Ring are challenging. About one third of the beam energy is deposited along the magnets by the decay electrons. As a possible solution an elliptical tungsten absorber could intercept the decay electrons and absorb the heat limiting the heat load on superconducting coils to the acceptable level. In this paper we describe the main design issues of dipoles with an elliptical aperture taking into consideration the field and field quality. The temperature margin and the forces in the coils are presented as well.

THPPD050

Fast Ramping Arbitrary Waveform Power Supplies for Correction Coils in a Circular Electron Accelerator

controls, dipole, power-supply, resonance

3623

A. Dieckmann, A. Balling, O. Boldt, F. Frommberger, W. Hillert, W. Lindenberg
ELSA, Bonn, Germany

New fast ramping power supplies working in pulsed bridge technology upgrade the existing Corrector System at ELSA. Current changes of ±0.8 A/msec are achieved. The newly developed CAN-Bus Interface allows linear interpolation of up to 250 support points with minimal time steps of 1msec. The first stage uses 24 power supplies to improve the position of the beam orbit in the horizontal plane using dipole correction coils. It will be extended to include the vertical plane with new corrector coils in the near future. This poster describes the operating principles of the power supply and the interface.

THPPD070

Design of High Power Pulse Modulator for Driving of Twystron used in S-band Linear Accelerator

vacuum, klystron, power-supply, cathode

3674

V. Aslani, F. AbbasiDavani, F. Ghasemi, M.Sh. Shafiee
sbu, Tehran, Iran

This design related to an s-band linear accelerator that the main tube and buncher of it have been made. RF power supply is used in this accelerator tube made up of a Twystron with 2.5 MW peak power and frequency band width 2.9~3.1 GHz. This paper offers the design of modulator for this RF amplifier. This modulator design uses solid-state method and is under construction with specification of ; Adjustable voltage from 0 to 120 kV, adjustable pulse width 2 until7μsecond, adjustable repetition rate 80-120 Hz ,ripple less than0.25% and efficiency up 80 percent. This system designed with series of 6 modules that each of them provides 5kV and IGBT switches that transform the voltage on the pulse transformer.

THPPD084

Analysis of Beam Loss Induced Abort Kicker Instability

radiation, high-voltage, kicker, factory

3713

W. Zhang, L. A. Ahrens, W. Fischer, H. Hahn, J.-L. Mi, C. Pai, J. Sandberg, Y. Tan
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Through more than a decade of operation, we have noticed the phenomena of beam loss induced kicker instability in the RHIC beam abort systems. In this study, we analyze the short term beam loss before abort kicker pre-fire events and operation conditions before capacitor failures. Beam loss has caused capacitor failures and elevated radiation level concentrated at failed end of capacitor has been observed. We are interested in beam loss induced radiation and heat dissipation in large oil filled capacitors and beam triggered thyratron conduction. We hope the analysis result would lead to better protection of the abort systems and improved stability of the RHIC operation.

THPPP002

Operation of the HESR Storage Ring of the FAIR Project with Ions and Rare Isotopes

ion, target, antiproton, storage-ring

3722

M. Steck, C. Dimopoulou, A. Dolinskii, T. Katayama, Yu.A. Litvinov, T. Stöhlker
GSI, Darmstadt, Germany
R. Maier, D. Prasuhn, H. Stockhorst
FZJ, Jülich, Germany

The HESR storage ring of the FAIR project is designed for experiments with cooled antiprotons. The HESR receives pre-cooled antiprotons from the Collector Ring CR which is also designed for cooling of rare isotope beams. The magnetic rigidity of 13 Tm is the same for the pre-cooling of antiprotons and rare isotopes in the CR. Therefore the transfer of ions or rare isotopes from the CR to the HESR can be performed under similar condition, except the different polarity of the magnetic components. This is an option for the first stage of the FAIR project when no other storage ring is available for experiments with stored ions. In the HESR the ions can be decelerated or accelerated, like the antiprotons, to energies corresponding to the magnetic rigidity range from 5 to 50 Tm. The planned beam cooling systems of the HESR, stochastic and electron cooling, can be applied to improve the quality of the ion beams in the HESR and support experiments using an internal target or the accumulation of rare isotope beams in the HESR. Scenarios for operating the HESR with ions and rare isotopes as well as achievable performance, beam intensity and quality for internal experiments will be discussed.

THPPP008

The ELENA Project: Progress in the Design

extraction, vacuum, antiproton, emittance

3740

T. Eriksson, W. Bartmann, P. Belochitskii, H. Breuker, F. Butin, C. Carli, R. Kersevan, M. Martini, S. Maury, S. Pasinelli, G. Tranquille
CERN, Geneva, Switzerland
W. Oelert
Forschungszentrum Jülich GmbH, Institut fur Nuklearchemie (INC), Jülich, Germany

The Extra Low ENergy Antiproton ring (ELENA) project started in June 2011 and is aimed at substantially increasing the number of antiprotons delivered to the Antiproton Decelerator (AD) physics community. ELENA will be a small machine that receives antiprotons from AD at 5.3 MeV kinetic energy and decelerates them further down to 100 keV. It will be equipped with an electron cooler to avoid beam losses during deceleration and to reduce beam phase space at extraction. Design work is progressing with emphasis on machine parameters and design as well as infrastructure, ring, transfer lines and vital subsystem design.

THPPP017

ELENA: From the First Ideas to the Project

antiproton, extraction, rfq, vacuum

3764

G. Tranquille, P. Belochitskii, T. Eriksson, S. Maury
CERN, Geneva, Switzerland
W. Oelert
Forschungszentrum Jülich GmbH, Institut fur Nuklearchemie (INC), Jülich, Germany

Successful commissioning of the CERN Antiproton Decelerator (AD) in 2000 was followed by significant progress in the creation of antihydrogen atoms. The extraction energy of the decelerated antiprotons is nevertheless very high compared to that required by experiments and results in a trapping efficiency of only 0.1% to 3%. To improve this value by an order of magnitude the study of an Extra Low ENergy Antiproton ring (ELENA) started in 2003 and was approved as a CERN construction project in 2011. During these years the choice of the main machine parameters such as the beam extraction energy, emittance and bunch length were defined, taking into account requests from the physics community. The main challenges were also identified, such as dealing with the large space charge tune, the ultra high vacuum required and the tight requirements for the electron cooler. Housing the ELENA ring within the AD hall significantly reduced the project cost as well as simplifying the beam transfer from AD to ELENA and from ELENA to the existing experimental areas. This contribution will follow ELENA from its beginnings to the final, approved project proposal.

THPPP027

The Design of a Large Booster Ring for the Medium Energy Electron-Ion Collider at JLab

booster, ion, collider, dipole

3791

E.W. Nissen, T. Satogata, Y. Zhang
JLAB, Newport News, Virginia, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
In this paper, we present the current design of the large booster ring for the Medium Energy Electron-Ion Collder (MEIC) at JLab. The booster ring takes 3 GeV protons or ions of equivalent energy from a pre-booster ring, and accelerates them to 20 GeV for protons or equivalent energy for light to heavy ions before sending them to the ion collider ring. The present design calls for a figure-8 shape of the ring for superior preservation of ion polarization. The ring is made of warm magnets and shares a tunnel with the two collider rings. Acceleration is achieved by warm RF systems. A linear optics has been designed with the transition energy above the highest beam energy in the ring so crossing of transition energy will be avoided. Preliminary beam dynamics studies including chromaticity compensation, analyses of dynamic aperture, working point and high order effects are also presented in this paper.

THPPP049

Tuning Procedure for the LINAC4 PI Mode Structure (PIMS)

simulation, cavity, linac, coupling

3850

P. Ugena Tirado, F. Gerigk, R. Wegner
CERN, Geneva, Switzerland

PI-Mode-Structure (PIMS) cavities will be used in the high energy section of LINAC4 (10²-160 MeV). Each cavity is made of 7 coupled cells, operated in the π-mode at a resonant frequency of 352.2 MHz. The cell length remains constant for each of the 12 cavities but changes from cavity to cavity to synchronise with the increased beam energy. This paper reports on the tuning process required to get a constant voltage in each cell at the resonant frequency and consisting in re-machining to the required level the tuning rings located on each cell-wall. An algorithm based on single cell detuning, equivalent circuit simulations and precise 3D simulations for the 3 different cell types of each cavity has been developed and successfully applied to the tuning of the first PIMS cavity. In order to reduce the simulation effort for the remaining 11 cavities, an interpolation algorithm based on 3 cavities has been developed and validated. In a second tuning step, after the electron beam welding of all cells, the final adjustment of single-cell frequencies and field flatness is achieved by cutting the length of one plunger tuner per cell.

THPPP067

H⁻ Beam Loss and Evidence for Intrabeam Stripping in the LANSCE Linac

linac, ion, radiation, emittance

3892

L. Rybarcyk, C.T. Kelsey, R.C. McCrady, X. Pang
LANL, Los Alamos, New Mexico, USA

Funding: U.S. Dept. of Energy, NNSA, under contract DE-AC52-06NA25396.
The LANSCE accelerator complex is a multi-beam, multi-user facility that provides high-intensity H⁺ and H⁻ particle beams for a variety of user programs. At the heart of the facility is a room temperature linac that is comprised of 100-MeV drift tube and 800-MeV coupled cavity linac (CCL) structures. Although both beams are similar in intensity and emittance, the beam-loss monitors along the CCL show a trend of increased loss for H⁻ that is not present for H⁺. This difference is attributed to stripping mechanisms that affect H⁻ and not H⁺. We present the results of an analysis of H⁻ beam loss along the CCL that incorporates beam spill measurements, beam dynamics simulations, analytical models and radiation transport estimates using the MCNPX code. The results indicate a significant fraction of these additional losses result from intrabeam stripping.

THPPR002

The Undulator Control System for the European XFEL

undulator, controls, photon, quadrupole

3966

S. Karabekyan, A. Beckmann, J. Pflüger
European XFEL GmbH, Hamburg, Germany
N. Burandt, J. Kuhn
Beckhoff Automation GmbH, Verl, Germany
A. Schöps
DESY, Hamburg, Germany

The European XFEL project is a 4th generation light source. The first beam will be delivered in the beginning of 2015 and will produce spatially coherent ≤80fs short photon pulses with a peak brilliance of 10³²–10³⁴ photons/s/mm²/mrad²/0.1% BW in the energy range from 0.26 to 29 keV at electron beam energies of 10.5 GeV, 14 GeV, or 17.5 GeV . The Undulator systems are used to produce photon beams for SASE 1, SASE 2 and SASE 3. Each undulator system consists of an array of undulator cells installed in a row along the electron beam. A single undulator cell itself consists of a planar undulator, a phase shifter, magnetic field correction coils and a quadrupole mover. This paper describes the design of the entire undulator control system including local and global control. It presents a concept of integration of the undulator control into the accelerator control system as well as into the experiment control.

THPPR009

Optimization of the Electron Beam Extraction Efficiency in a Booster for TLS

extraction, booster, factory, kicker

3981

H.C. Chen, H.-P. Chang, H.H. Chen, S. Fann, S.J. Huang, J.A. Li, C.C. Liang, Y.K. Lin, Y.-C. Liu
NSRRC, Hsinchu, Taiwan

The Response Surface Methodology (RSM), is used to study the optimization process of the electron beam extraction efficiency for Taiwan Light Source (TLS) in NSRRC. A study model was constructed based on the Artificial Neural Network (ANN) theory by using selected beam extraction tuning knobs as the variables. An optimization procedure is developed by taking extraction efficiency as the objective function and the selected beam tuning knobs as the variables. Furthermore, this theoretical model and optimization procedure have been put into practice in verifying how effectively the model can accomplish. By properly applying the constructed optimization procedure for electron beam extraction study, the efficiency has been improved effectively. The details of the study will be reported in this paper.

THPPR025

Operational Efficiency of the AIRIX Accelerator Since its Commissioning

high-voltage, site, vacuum, induction

4017

H. Dzitko, V. Bernigaud, A. Georges, B. Gouin, G. Grandpierre, M. Mouillet
CEA, Pontfaverger-Moronvilliers, France
L. Buche, Y. Collet, S. Combacon, G. Gobert, R. Nicolas, R. Reynaud
CEA/DAM/DIF, Arpajon, France

AIRIX is a high current (19 MeV, 2 kA) electron linear induction accelerator used as a 60 ns single shot X-ray source for hydrodynamic experiments. As single shot experiments are performed, the best performances and a high reliability level must be met for each experiment. This accelerator has been running for hydroshot experiments since 2000 and several thousands electron and X-ray beams have been produced so far. The functioning time of the AIRIX machine in the CEA/Moronvilliers test site is now coming to its end. From mid-2012, it will be then refurbished, dismounted and moved to another CEA test site. This paper draws up the report of AIRIX operations over this long eleven-year period. Maintenance policy, relative cost efficiency, reliability and performance results of the AIRIX accelerator over this period are dealt with and discussed.

THPPR027

Sustaining the Reliability of the MAMI-C Accelerator

microtron, controls, linac, klystron

4023

H.-J. Kreidel, K. Aulenbacher, M. Dehn, F. Fichtner, R.G. Heine, P. Jennewein, W. Klag, U.L. Ludwig, J.R. Röthgen, V. Tioukine
IKP, Mainz, Germany

Funding: This work has been supported by CRC 443 of the Deutsche Forschungsgemeinschaft.
A status report of the 1.6 GeV electron accelerator MAMI-C is given together with an outlook towards its future operation. We describe problems which are imposed by some aging technical subcomponents in the first stages which have in part been in operation for almost 30 years. We present measures how to sustain the achieved extremely high reliability during the upcoming new research programs which are foreseen to last at least for one more decade.

THPPR029

A New Control Room for SLAC Accelerators

controls, linac, synchrotron, target

4029

R.A. Erickson, E. Guerra, M. Stanek, Z. Van Hoover, J. Warren
SLAC, Menlo Park, California, USA

Funding: This work was supported by the Department of Energy contract DE-AC02-76SF00515.
We propose to construct a new control room at SLAC to unify and improve the operation of the LCLS, SPEAR3, and FACET accelerator facilities, and to provide the space and flexibility needed to support the LCLS-II and proposed new test beam facilities. The existing control rooms for the linac and SPEAR3 have been upgraded in various ways over the last decade, but their basic features have remained unchanged. We propose to build a larger modern Accelerator Control Room (ACR) in the new Research Support Building (RSB), which is currently under construction at SLAC. Shifting the center of control for the accelerator facilities entails both technical and administrative challenges. In this paper, we describe the motivation and design concept for the ACR and the remaining challenges to completing this project.

THPPR032

A Split-Electrode for Clearing Scattered Electrons in the RHIC E-Lens

proton, ion, scattering, solenoid

4038

X. Gu, W. Fischer, D.M. Gassner, K. Hamdi, J. Hock, Y. Luo, C. Montag, M. Okamura, A.I. Pikin, P. Thieberger
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
We are designing two electron lenses that will be installed at RHIC IR10 to compensate for the head-on beam-beam effect. To clear accumulated scattered electrons from 100 GeV proton-electron head-on collisions in the e-lens, a clearing split electrode may be constructed. The feasibility of this proposed electrode was demonstrated via the CST Particle Studio and Opera program simulations. By splitting one of the drift tubes in the e-lens and applying ~ 380 V across the two parts, the scattered electrons can be cleared out within several hundred micro-seconds. At the same time we can restrict the unwanted shift of the primary electron-beam that already passed the 2-m interaction region in e-lens, to less than 15um.

THPPR033

Tests and Measurements with the Embedded Radiation-monitor-system Prototype for Dosimetry at the European XFEL

radiation, undulator, linac, neutron

4041

F. Schmidt-Föhre, D. Nölle, R. Susen, K. Wittenburg
DESY, Hamburg, Germany

A new Embedded Radiation-Monitor-System is currently under development for use in the upcoming European XFEL, that is being built at a length of approx. 3.4 km between the campus of the Deutsches Elektronen-Synchrotron DESY at Hamburg and Schenefeld at Schleswig-Holstein. Most of the electronic systems cabinets for machine control, diagnostics and safety of the XFEL will be located inside the accelerator tunnel. To prevent significant radiation damage at electronic systems in certain sections of the XFEL, all electronic cabinets inside the tunnel will be sufficiently shielded according to pre-estimated radiation levels. In addition, accumulated dose inside these electronic cabinets and in undulator regions will be monitored for the impact of Gamma- and Neutron-radiation by a new radiation monitor system. Life cycle estimations for these electronics and the undulators will provide safety limits for correct function and in time part exchange due to radiation, before significant radiation damage occurs. A prototype of the Gamma radiation-monitor system section has been successfully designed and tested at the DESY Linac II. Prototype tests and according measurements will be presented.

THPPR042

Optimisation of an Inverse Compton Scattering Experiment with a Real Time Detection Scheme Based on a Radio Luminescent Screen and Comparison of the X-rays Beam Characteristics with Simulations

photon, laser, emittance, scattering

4068

A.S. Chauchat, JP. Brasile
TCS, Colombes, France
A. Binet, V. Le Flanchec, J-P. Nègre
CEA/DAM/DIF, Arpajon, France
J.-M. Ortega
LCP/CLIO, Orsay, Cedex, France

To optimize the detection of an 11-keV X-Ray beam produced by Inverse Compton Scattering at the ELSA facility*, with a 17 MeV electron beam and a 532 nm laser, we demonstrate the use of a very sensitive detection scheme, based on a radio luminescent screen used in the spontaneous emission regime. It has proven to be very sensitive and very effective to detect 11-keV X-Rays while rejecting the overall ambient noise produced in a harder spectral range. It allowed us to optimize the electron-photon interaction probability by observing in real time the effect of both beams transport parameters. We could then compare simulation results with experimental measurements that appear to be in good agreement.
*A.S. Chauchat et al. Instrumentation developments for production and characterization of Inverse Compton Scattering X-rays and first results with a 17 MeV electron beam, NIMA, V.622, I.1, P.129-135

THPPR044

A New Electron Beam Test Facility (EBTF) at Daresbury Laboratory for Industrial Accelerator System Development

gun, FEL, laser, vacuum

4074

P.A. McIntosh, D. Angal-Kalinin, S.R. Buckley, J.A. Clarke, A.R. Goulden, C. Hill, S.P. Jamison, J.K. Jones, A. Kalinin, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, T.T. Ng, B.J.A. Shepherd, R.J. Smith, S.L. Smith, N. Thompson, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
N. Bliss, G.P. Diakun, A. Gleeson, T.J. Jones, B.G. Martlew, A.J. Moss, L. Nicholson, M.D. Roper, C.J. White
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

Recent UK government funding has facilitated the implementation of a unique accelerator test facility which can provide enabling infrastructures targeted for the development and testing of novel and compact accelerator technologies, specifically through partnership with industry and aimed at addressing applications for medicine, health, security, energy and industrial processing. The infrastructure provision on the Daresbury Science and Innovation Campus (DSIC) will permit research into areas of accelerator technologies which have the potential to revolutionise the cost, compactness and efficiency of such systems. The main element of the infrastructure will be a high performance and flexible electron beam injector facility, feeding customised state-of-the-art testing enclosures and associated support infrastructure. The facility operating parameters and implementation status will be described, along with primary areas of commercialised technology development opportunities.

THPPR049

Study on Electron Microbeam Generation for MRT Based on Photo-cathode RF-Gun

gun, cathode, laser, radiation

4086

Y. Yoshida, K. Sakaue, M. Washio
RISE, Tokyo, Japan

We have been developing an MRT (Microbeam Radiation Therapy) based on Cs-Te photo cathode RF-Gun at Waseda University. MRT is proposed to treat tumor by using array of several micro-meter parallel beams. In this therapy, irradiated normal tissue repairs itself, by contrast, even a non-irradiated tumor tissue dies. In the other words, the microbeam enhances the radiation sensitivity difference between normal and tumor issues. Therefore, MRT is considered one of the most useful tumor therapies in the future. We have generated electron microbeam by tungsten collimator slit and analyzed their dose distribution in air and in the PMMA phantom. We have used radiochromic film called GAFCHROMIC dosimetry film type HD-810 to measure them. We have compared these experimental results with Monte Carlo simulation of the dose distribution using the EGS5 code. In this conference, we would like to report the electron microbeam procedure, optimization of irradiation condition, evaluation of microbeam specifications and future prospects.

THPPR050

Fabrication and High Power RF Test of A C-band 6MeV Standing-wave Linear Accelerating Structure

simulation, gun, coupling, target

4089

J.H. Shao, H. Chen, H. Zha
TUB, Beijing, People's Republic of China

We have designed a C-band standing-wave bi-periodic on-axis coupled linear accelerating structure for industrial and medical applications [1]. The output electron energy is 6MeV and the pulse current intensity is 100mA. The structure has been fabricated and measured in cold test. The cold test results show a good agreement between the simulation and actual measurement. At present, it’s under high power RF test. In this paper, we illustrate the fabrication, the results of cold test and newly high power RF test.

THPPR057

Feasibility Study Gamma-induced Positron Annihilation Lifetime Spectroscopy in an Electron Storage Ring

laser, positron, target, storage-ring

4103

Y. Taira, H. Toyokawa
AIST, Tsukuba, Ibaraki, Japan
M. Adachi, M. Katoh, S. Tanaka
UVSOR, Okazaki, Japan
N. Yamamoto
Nagoya University, Nagoya, Japan

Funding: This work was supported by Grants-in-Aid for Scientific Research (22360297) and Grant-in-Aid for JSPS Fellows (235193).
Positron annihilation lifetime spectroscopy (PALS) has proved to be very sensitive tool to characterize materials and study defects. However PALS has been restricted to thin samples because of the limited range of positrons in materials. We have developed new techniques for PALS, in which laser Compton scattered (LCS) gamma rays are used to produce positrons inside materials via pair production. Ultra-short gamma ray pulse source* with pulse width of 5 ps (FWHM) generated by 90-degree collision LCS was applied to PALS for the first time. The short pulse width of the gamma-rays that is negligible compared to estimated positron lifetime (100 ps to ns range) is essential to PALS. The experiment was carried out at the UVSOR-II electron storage ring, a 750 MeV synchrotron light source. The positron annihilation lifetime, 199 ± 10 ps, in a bulk sample of lead was successfully measured by using the ultra-short gamma ray pulse.
* Y. Taira, et al., Nucl. Instr. And Meth. A 637 (2011) S116.

THPPR058

Pulse Radiolysis using Double-decker Femtosecond Electron Beam from a Photocathode RF Gun

linac, laser, gun, radiation

4106

K. Kan, T. Kondoh, K. Norizawa, A. Ogata, J. Yang, Y. Yoshida
ISIR, Osaka, Japan

Pulse radiolysis, which utilizes an electron bunch and a probe light (laser), is a powerful tool that can be used for an observation of ultrafast radiation-induced phenomena. The time resolution in pulse radiolysis depends on the electron bunch length, the probe-light width, and the timing jitter between the electron bunch and the probe light. In order to reduce the jitter, double-decker accelerator, in which separated laser was injected on a photocathode RF gun for a generation of synchronized double electron beams, was applied to pulse radiolysis. One electron beam was used as a pump source of a material, e. g. water, and another as a probe light at 800 nm wavelength with Cherenkov radiation.

THPPR059

Progress of the Equivalent Velocity Spectroscopy Method for Femtosecond Pulse Radiolysis by Pulse Rotation and Pulse Compression

laser, cathode, radiation, linac

4109

T. Kondoh, K. Kan, K. Norizawa, A. Ogata, S. Tagawa, J. Yang, Y. Yoshida
ISIR, Osaka, Japan
H. Kobayashi
KEK, Ibaraki, Japan

Femtosecond pulse radiolysis is developed for studies of electron beam induced ultra-fast reaction in matter. 98 fs electron pulse was generated by a photocathode RF gun LINAC with a magnetic bunch compressor. However for more fine time resolution, the Equivalent velocity spectroscopy (EVS) method is required to avoid degradation of time resolution caused by velocity difference between electron and analysing light in sample. In the EVS method, incident analysing light is oblique toward electron beam with an angle associated with refractive index of sample, and then, electron pulse is rotated toward the direction of travel to overlap with light pulse. In previous studies, pulse rotation had not been compatible with pulse compression. However, by oblique incident of light to the photocathode, pulse rotation was compatible with pulse compression, and the time resolution was improved by principle of the equivalent velocity spectroscopy.

THPPR065

High Flux Laser-Compton Scattered Gamma-ray Source by Compressed Nd:YAG Laser Pulse.

laser, photon, microtron, resonance

4124

I. Daito, R. Hajima, T. Hayakawa, Y. Hayashi, M. Kando, H. Kotaki, T. Shizuma
JAEA, Kyoto, Japan
H. Ohgaki
Kyoto University, Institute for Advanced Energy, Kyoto, Japan

A non-destructive detection system of nuclear materials hidden in cargo containers is under development in Japan Atomic Energy Agency and Kyoto University. The system is able to be used for the identification of isotopes of special nuclear material in a container by employing Nuclear Resonance Fluorescence triggered by mono-energetic Laser Compton Scattered (LCS) gamma-ray tuned at the energy of the nuclear resonance. One of the most important technologies for such system is generation of gamma-rays at a flux of 3 x10⁵ photon/s. In order to achieve this gamma-ray flux with a compact system, a pulse compression system for Nd:YAG laser based on Stimulated Brillouin Scattering (SBS) has been developed. The laser pulse with a duration of 10 ns (FWHM) from a commercially available Nd:YAG laser is compressed down to a few hundreds ps. As a feasibility study of the proposed system, 400 keV gamma-ray generation is performed at Kansai Photon Science Institute by using 150 MeV electron beam from microtron accelerator and compressed Nd:YAG laser. Experimental results of laser pulse compression and gamma-ray generation are presented.

THPPR066

Racetrack Microtron for Nondestructive Nuclear Material Detection System

linac, acceleration, gun, microtron

4127

T. Hori, T. Kii, R. Kinjo, H. Ohgaki, M. Omer, H. Zen
Kyoto University, Institute for Advanced Energy, Kyoto, Japan
I. Daito, R. Hajima, T. Hayakawa, M. Kando, H. Kotaki
JAEA, Kyoto, Japan

A nuclear material detection system using the quasi-monochromatic gamma-ray beam from a laser Compton Backscattering source has been proposed for the container inspection, where nuclear resonance fluorescence method would be employed for the specific isotope identification such as U-235. In the system an electron beam of good quality at about 220 MeV for the laser Compton backscattering is required. One candidate for such the practical use is a racetrack microtron which design is based on the existing 150 MeV microtron at JAEA.

THPPR068

Laser Compton Scattering X-rays as a Tool for K-edge Densitometry

photon, laser, scattering, radiation

4133

M. Titberidze, K. Chouffani
IAC, Pocatello, IDAHO, USA

There is a huge interest in bright and tunable X-ray sources. These sources can be used in various research fields, including medical, biological and industrial fields. Laser Compton Scattering (LCS) technique gives us possibility to generate tunable, quasi monochromatic and polarized X-ray beam. One of the applications of LCS is the detection and quantitative identification of special nuclear materials (SNM) using K-edge densitometry(KED)method. Our group was the first one who has used a quasi-monochromatic LCS source to carry out KED experiments. The experiments showed that LCS technique could be used for SNM detection and quantification.

THPPR069

Compact, Inexpensive X-Band Linacs as Radioactive Isotope Source Replacements

linac, simulation, radiation, coupling

4136

S. Boucher, R.B. Agustsson, X.D. Ding, L. Faillace, P. Frigola, A.Y. Murokh, M. Ruelas, S. Storms
RadiaBeam, Santa Monica, USA

Funding: Work supported by DNDO Phase II SBIR HSHQDC-10-C-00148 and DOE Phase II SBIR DE-SC0000865.
Radioisotope sources are still commonly used in a variety of industrial and medical applications. The US National Research Council has identified as a priority the replacement of high-activity sources with alternative technologies, due to the risk of accidents and diversion by terrorists for use in radiological dispersal devices (“dirty bombs”). RadiaBeam Technologies is developing novel, compact, inexpensive linear accelerators for use in a variety of such applications as cost-effective replacements. The technology is based on the MicroLinac (originally developed at SLAC), an X-band linear accelerator powered by an inexpensive and commonly available magnetron. Prototypes are currently under construction. This paper will describe the design, engineering, fabrication and future testing of these linacs at RadiaBeam. Future development plans will also be discussed.

THPPR070

Development of Multi-collision Laser Compton Scattering X-ray Source on the Basis of Compact S-band Electron Linac

laser, cavity, photon, linac

4139

R. Kuroda, M. Koike, E. Miura, Y. Taira, H. Toyokawa, K. Yamada, E. Yamaguchi
AIST, Tsukuba, Ibaraki, Japan
M. Kumaki
RISE, Tokyo, Japan

A compact hard X-ray source via laser Compton scattering is required for biological, medical and industrial science because it has many benefits about generated X-rays such as short pulse, quasi-monochromatic, energy tunability and good directivity. Our X-ray source is conventionally the single collision system between an electron pulse and a laser pulse. To increase X-ray yields, we have developed a multi-collision system with a multi-bunch electron beam and a laser optical cavity. The multi-bunch electron beam has already been generated from a Cs-Te photocathode rf gun system using a multi-pulse UV laser. The laser optical cavity have developed like a regenerative amplification including the collision point between the electron pulse and the laser pulse which is based on the Ti:Sa laser with a mode-locked frequency of 79.33 MHz. In this preliminary experiment, the modulated seed laser pulses were generated and leaded to the cavity, so that laser build-up amplification was performed in the cavity length of 3.78 m with two seed pulses. In this conference, we will describe the results of preliminary experiments for the multi-collision system and future plans.

THPPR072

High Power of 10 MeV, 25 kW Electron LINAC for Irradiation Applications

linac, vacuum, simulation, radiation

4142

Y.J. Pei, G. Feng, Y. Hong, K. Jin, S. Lu, L. Shang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Using the electron beam to sterilize medical products and cosmetics, and food preservation and so on, has become important and efficient manners recently in number and variety. This paper describes the design, construction, and commissioning of a high power electron LINAC which can provide beam energy of 10 MeV, beam power of 25 kW. The paper also gives beam dynamic simulation results where beam loading effect was taken into account, and running parameters.

FRXBA01

Overview of Recent Progress on High Repetition Rate, High Brightness Electron Guns

gun, cathode, SRF, brightness

4160

F. Sannibale
LBNL, Berkeley, California, USA

In the last few years, the formidable results of x-ray light sources based on FELs opened the door to classes of experiments not accessible before. Operating facilities have relatively low repetition rates (~ 10-100 Hz), and the natural step forward consists in the development of FEL light sources capable of extending their rates by orders of magnitude in the MHz regime. Additionally, ERL based x-ray facilities with their promise of outstanding performance also require extremely high, GHz-class repetition rates. The development of such facilities would represent the next revolutionary step in terms of science capability. To operate such light sources, an electron injector capable of MHz/GHz repetition rates and with the brightness required by X-ray FELs or ERLs is required. Such injector presently does not exist. In response to that, many groups around the world are intensively working on different schemes and technologies that show the potential for achieving the desired results. This presentation includes a description of the requirements for such injectors, an overview of the pursued technologies, and a review of the results obtained so far by the groups active in the field.

Slides FRXBA01 [6.290 MB]

FRXBB01

Femtosecond Electron Guns for Ultrafast Electron Diffraction

gun, emittance, laser, cathode

4170

J. Yang, K. Kan, T. Kondoh, N. Naruse, K. Tanimura, Y. Yoshida
ISIR, Osaka, Japan
J. Urakawa
KEK, Ibaraki, Japan

This talk should describe the development of electron guns for producing femtosecond electron pulses with low (<0.1 micron) emittance, for ultrafast electron diffraction. Comparisons should be made between the systems developed by groups in Asia, Europe and America, outlining any similarities and contrasts. The focus should be on the technology for generating, accelerating, and controlling the bunches, but some description of the science applications should also be included. Finally, prospects for future developments should be considered.

Slides FRXBB01 [7.004 MB]

FRYAP01

The Future of X-ray FELs

FEL, undulator, laser, linac

4180

H.-H. Braun
Paul Scherrer Institut, Villigen, Switzerland

Recent years have brought enormous progress with X-ray FELs. With LCLS and SACLA two facilities with quite different technological approaches have shown the feasibility of SASE FELs in the hard X-ray regime while the SASE FEL FLASH and the recently commissioned laser seeded FEL FERMI@ELETTRA provide coherent light beams of unprecedented brightness at EUV and soft X-ray wavelength. First user experiments at these facilities demonstrate the vast scientific potential of this new type of instrument and have accelerated and triggered R&D and planning for other facilities of its kind worldwide. Projects under construction or in advanced stage of planning are European XFEL, LCLS II, SwissFEL, PAL XFEL, Shanghai XFEL and NGLS. Worldwide R&D efforts for XFELs try to improve performance and reduce size and cost. Focuses are on injector, linac and undulator technologies as well as on FEL seeding methods.

Slides FRYAP01 [24.324 MB]

FRYCP01

Physics Results at the LHC and Implications for Future HEP Programmes

collider, proton, luminosity, linear-collider

4190

R. Heuer
CERN, Geneva, Switzerland

This presentation should review the accumulated data of the TEVATRON and the first two years of LHC operation, highlighting major results and findings for high energy physics. This talk should highlight the most burning questions in high energy physics that emerged in light of these new results and discuss their implication for the planning and preparation of future accelerator projects.

Slides FRYCP01 [14.536 MB]