IPAC2012 - List of Keywords (simulation)

Paper	Title	Other Keywords	Page
MOYCP01	Design and Simulation of IOTA - a Novel Concept of Integrable Optics Test Accelerator	electron, focusing, betatron, optics	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]

MOOBB01	Transverse-to-longitudinal Emittance-exchange with an Energy Chirped Beam	emittance, cavity, electron, 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]

MOEPPB007	Studies of eRHIC Coherent Instabilities	proton, impedance, betatron, space-charge	91
	G. Wang, M. Blaskiewicz 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 the presence of an effective coherent electron cooling, the rms ion bunch length in eRHIC will be kept at 8.4cm, which is about a factor of 3 shorter than the current RHIC rms bunch length. Together with a factor of 2 increase in bunch intensity, coherent instabilities could be a potential limitation for achieving desired machine performance. In this study, we use the tracking code TRANFT to find thresholds and growth rates for various single bunch and coupled bunch instabilities with linear chromaticity and amplitude dependent tune shift taken into account. Based on the simulation results, requirements of machine parameters such as rf voltage, linear chromaticity, and octupole strength are specified to avoid these instabilities.

MOEPPB008	Simulation of Hollow Electron Beam Collimation in the Fermilab Tevatron Collider	electron, 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.

MOEPPB012	High-performance Beam Simulator for the LANSCE Linac	space-charge, linac, controls, EPICS	103
	X. Pang, S.A. Baily, L. Rybarcyk 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 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 a 100-MeV drift tube linac and an 800-MeV coupled cavity linac. During beam operations, linac parameters are adjusted to maintain minimal beam spill, but without detailed knowledge of the beam distribution. A more desirable situation would be one where knowledge of the beam distribution along the linac is available to aid in the optimization of the linac operation and beam performance. We are presently developing a high performance simulator that will provide valuable information about the beam distribution in pseudo real-time during linac operations. The heart of the simulator is based upon the multiparticle beam dynamics code PARMILA, but implemented in C++ using NVIDIA’s CUDA technology for Graphics Processing unit (GPU) hardware. Linac operating set points will be provided by the EPICS control system so that changes are tracked and the simulation results updated automatically. Details regarding the approach, benefits and performance will be presented.

MOEPPB013	Simulation and Measurement of Beam Loss in the Narrow-Gap Undulator Straight Section of the Advanced Photon Source Storage Ring	undulator, vacuum, radiation, neutron	106
	J.C. Dooling, 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 number DE-AC02-06CH11357. Simulations indicate the removal of a scraper/collimator in the Sector 37 straight section (SS) of the Advanced Photon Source storage ring (SR) results in increased beam loss in the remaining narrow-gap, insertion device SS, ID4. Modeling with elegant provides loss distributions in the 5-mm aperture vacuum chamber of ID4 and includes the effects of rf system muting and quantum excitation in the bunch. The loss distributions are then used as input to a MARS model of the SS that includes undulator geometry. ID4 has been instrumented with additional monitoring to capture beam loss events, particularly beam dumps. Cerenkov detectors and fiber-optic cable bundles are used to capture temporal profiles of beam loss events. Beam dumps deliver 2600 J to the vacuum chamber and surrounding hardware including undulators. Data indicate a variety of temporal profiles occur during the beam dumps, with the shortest lasting 6 microseconds, FWHM (<2 turns). Such high power and power densities can lead to physical damage of vacuum components if not handled correctly. Touschek scattering loss is also a concern for undulator demagnetization. Comparison of modeling and measurements will be presented.

MOPPC001	Simulation of electron-cloud heat load for the cold arcs of the large hadron collider	electron, 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.

MOPPC003	Very Fast LHC Crab Cavity Failures and their Mitigation	luminosity, betatron, cavity, optics	121
	T. Baer, R. Calaga, R. De Maria, S.D. Fartoukh, E. Jensen, R. Tomás, J. Tückmantel, J. Wenninger, B. Yee-Rendon, F. Zimmermann CERN, Geneva, Switzerland T. Baer University of Hamburg, Hamburg, Germany
	For the high-luminosity LHC upgrade program (HL-LHC), the installation of crab cavities (CCs) is needed to compensate the geometric luminosity loss due to the crossing angle and for luminosity leveling []. The baseline is a local scheme with CCs around the ATLAS and CMS experiments. In a failure case (e.g. a control failure or arcing in the coupler), the voltage and/or phase of a CC can change significantly with a very fast time constant of the order of 1 to 10 LHC turns. This can lead to large, global betatron oscillations of the beam. The impact of CC failures on the beam dynamics is discussed and the results from dedicated simulations are presented. Mitigation strategies to limit the impact of CC failures to an acceptable level are proposed. F. Zimmermann and O. Brüning, “Parameter Space for the LHC High-Luminosity Upgrade”, IPAC'12, MOPPC005, May 2012.

MOPPC018	Single/Few Bunch Space Charge Effects at 8 GeV in the Fermilab Main Injector	space-charge, background, factory, proton	163
	D.J. Scott, D. Capista, I. Kourbanis, K. Seiya, M.-J. Yang Fermilab, Batavia, USA
	For Project X, it is planned to inject a beam of 3 10¹¹ particles per bunch into the Main Injector. Therefore, at 8 GeV, there will be increased space charge tune shifts and an increased incoherent tune spread. In preparation for these higher intensity bunches exploratory studies have commenced looking at the transmission of different intensity bunches at different tunes. An experiment is described with results for bunch intensities between 20 and 172 10⁹ particles. To achieve the highest intensity bunches coalescing at 8 GeV is required, resulting in a longer bunch length. Comparisons show that similar transmission curves are obtained when the intensity and bunch length have increased by factors of 3.2 and 3.4 respectively, indicating the incoherent tune shifts are similar, as expected from theory. The results of these experiments will be used in conjugation with simulations to further study high intensity bunches in the Main Injector.

MOPPC023	Polarization Transmission at RHIC, Numerical Simulations	polarization, resonance, optics, proton	178
	F. Méot, M. Bai, C. Liu, M.G. Minty, V.H. Ranjbar BNL, Upton, Long Island, New York, USA
	Ray-tracing methods, using the computer code Zgoubi, have proven efficient for beam and spin dynamics simulations in RHIC (see earlier PAC and IPAC publications). More simulations and results are being produced, including spin code benchmarking and cross-checking, effects of strongest resonances and working point on transport of polarization, polarization with Run 9 and Run 11 measured ramp orbit and optics, polarization profiles, etc. The numerical methods involved are recalled, a status of the work is given.

MOPPC024	Modelling of the AGS Using Zgoubi - Status	optics, closed-orbit, multipole, coupling	181
	F. Méot, L. A. Ahrens, Y. Dutheil, J.W. Glenn, H. Huang, T. Roser, V. Schoefer, N. Tsoupas BNL, Upton, Long Island, New York, USA
	A computer model, based on the ray-tracing code Zgoubi, is being developed in view of on-line simulation of the RHIC injector AGS, and of beam and spin dynamics simulations and studies in the presence of the cold and warm helical partial snakes. A status of this work is given here.

MOPPC026	Simulations of Coherent Beam-Beam Effects with Head-on Compensation	electron, resonance, proton, 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.

MOPPC027	Synchro-Betatron Effects in the Presence of Large Piwinski Angle and Crab Cavities at the HL-LHC	betatron, luminosity, coupling, damping	190
	S.M. White BNL, Upton, Long Island, New York, USA R. Calaga CERN, Geneva, Switzerland R. Miyamoto ESS, Lund, Sweden
	Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP). The reduction of beta-star at the collision points for the high luminosity LHC (HL-LHC) requires an increment in the crossing angle to maintain the normalized beam separation to suppress the effects of long-range beam-beam interactions. However, increase in crossing angle may give rise to synchro-betatron resonances which may negatively affect the beam emittance and lifetime. 6D weak-strong and strong-strong simulations are performed to study the effect of synchro-betatron resonances in the context of the HL-LHC layout and its suppression via crab crossing.

MOPPC028	Coherent Beam-Beam Effects Observation and Mitigation at the RHIC Collider	emittance, damping, coupling, dipole	193
	S.M. White, M. Bai, W. Fischer, Y. Luo, A. Marusic, M.G. Minty 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. In polarized proton operation in RHIC coherent beam-beam modes are routinely observed with beam transfer function measurements in the vertical plane. With the existence of coherent modes a larger space is required in the tune diagram than without them and stable conditions can be compromised for operation with high intensity beams as foreseen for future luminosity upgrades. We report on experiments and simulations carried out to understand the existence of coherent modes in the vertical plane and their absence in the horizontal plane, and investigate possible mitigation strategies.

MOPPC029	Off-momentum Beat-beat Correction in the RHIC Proton Run	sextupole, quadrupole, proton, lattice	196
	Y. Luo, M. Bai, W. Fischer, A. Marusic, K. Mernick, S.M. White 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 this article we will present the measurement and correction of the off-momentum β^*-beat in the RHIC proton run. The beta-beat will be measured with the AC dipole and by shifting RF frequency. We will focus on the correction of the off-momentum beta-beat at the interaction points IP6 and IP8 with the arc chromatic sextupole families. The effects of the off-momentum beta-beat correction on the global chromaticities and dynamic aperture will be estimated through beam experiments and the numerical simulation.

MOPPC034	Use of Helical Transport Channels for Bunch Recombination	collider, luminosity, emittance, focusing	205
	D.V. Neuffer, K. Yonehara Fermilab, Batavia, USA C.M. Ankenbrandt, C. Y. Yoshikawa Muons, Inc, Batavia, USA
	Cooling scenarios for a high-luminosity Muon Collider require bunch recombination for optimal luminosity. In this paper we describe a new method for bunch recombination. We combine the high-chronicity of a helical transport channel (HTC) with the high-frequency bunching and phase-energy rotation concept (time-reversed) to obtain a compact bunch recombination system adapted to a muon collider scenario. We first present an idealized 1-D system with multiple chronicity transports. We then implement the concept in a single-chronicity channel, obtaining bunch recombination of 13 200MHz-spaced bunches to a single collider-ready bunch within a compact transport with modest rf requirements. That example is demonstrated within G4BL 3-D simulations. Variations and adaptations for different recombination requirements are discussed.

MOPPC037	Muon Collider Detector Backgrounds	collider, background, electron, 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, electron, hadron	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.

MOPPC042	Higgs Boson Muon Collider Factory: h⁰, A, H Studies	collider, factory, solenoid, dipole	226
	D.B. Cline, X.P. Ding, J.L. Lederman UCLA, Los Angeles, California, USA
	With the recent hints of the Higgs boson from the LHC and a mass near 125 GeV/c we re-propose to study and build a muon collider Higgs factory to study the Higgs in the S channel. This was first proposed in 1992 by the first author. It is essential to study the Higgs boson for clues to new physics. The formation of the DOE MAP program, recent advances in 6D μ cooling methods, simulation, and targeting make this a feasible project to initiate at this time. This collider would fit into the FNAL site.

MOPPC046	End-to-End G4Beamline Simulation of an Inverse Cyclotron for Muon Cooling	cyclotron, emittance, solenoid, extraction	238
	T.L. Hart, T.H. Luo, D.J. Summers UMiss, University, Mississippi, USA K. Paul Tech-X, Boulder, Colorado, USA
	An inverse cyclotron is a novel, intriguing idea for muon cooling necessary for proposed neutrino factories and muon colliders. We present the latest results of an end-to-end inverse cyclotron simulation that cools muons in the following sequence: single turn injection and initial cooling of 100 MeV kinetic energies to about 5 MeV with lithium hydrogen wedges; further substantial cooling to keV range kinetic energies and trapping with carbon foils and a rising electric field; and re-acceleration of the cooled, trapped muons back to 100 MeV. For neutrino factory and muon collider applications, the time of the entire cooling/trapping/re-acceleration process needs to be comparable to the muon lifetime so that decay losses are tolerable and the acceptance of the inverse cyclotron needs to be sufficiently large (on order 10 mm-rad normalized emittance). The latest progress toward these ends is presented.

MOPPC053	Modeling of Bending Magnets for SIRIUS	dipole, multipole, lattice, sextupole	250
	X.R. Resende, R. Basílio, L. Liu, P.P. Sanchez, G. Tosin LNLS, Campinas, Brazil
	The new Brazilian synchrotron source, Sirius, will be a 3 GeV storage ring with a triple bend lattice with a minimum emittance of 1.7 nm rad. The ring dipoles are excited with permanent magnets. The middle bend has a small 1.4 degree slice in its center with 1.94 T field and serve as an additional hard X-ray source with critical energy of 11.6 keV. Other bending magnets have low 0.50 T field with gradients, allowing for a further emittance reduction. The bending slice shows a longitudinal profile with no uniform field plateau and with long-range fringe fields which are coupled with the fields of neighbouring dipoles. To take into account the interaction of the field-intersecting dipoles, realistic 3D models of the magnets have been created and their field configuration solved using finite element techniques. Field maps calculated from the 3D magnet models were used for the construction of segmented models of bend elements in beam dynamics codes.

MOPPC054	Multi-code Modelling of Momentum Collimation in the TRIUMF ARIEL Linac	electron, gun, linac, 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.

MOPPC055	A New Platform for Global Optimization	linac, TRIUMF, solenoid, emittance	256
	C. Gong, Y.-C. Chao TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	Funding: Funding is received from Natural Sciences and Engineering Research Council of Canada and National Research Council of Canada for this research. This paper describes a new platform for the multi-objective global optimization of accelerator design. While local optimization is relatively simple, global optimization for accelerator design remains a challenging task. The user often must write many lines of code to combine the output of a large variety of simulation engines, then send the results to the optimization engine. The optimization code also requires significant revision when applied to different problems. This paper presents an alternative method. The TRIUMF optimization platform, based on the genetic algorithm, is an extension of the PISA framework. It uses a flexible XML input format, in which users can easily combine multiple physics engines, such as ASTRA and PARMELA, into the same optimization problem. The TRIUMF platform is also parallel capable, designed to take advantage of computation clusters such as WestGrid. Results of the optimization platform applied to TRIUMF's 50 MeV, 0.5 MW electron linac are shown.

MOPPC056	The SolMaxP Code	plasma, laser, target, beam-transport	259
	A. Chancé, N. Chauvin, R.D. Duperrier CEA/DSM/IRFU, France
	In modern sciences, use of high performance computing (HPC) has become a necessity to move forward in the modeling of complex systems. For large-scale instruments like accelerators, HPC permits the virtual prototyping of very onerous parts and, thus, helps to reduce development costs. The SolMaxP code (for Solving Maxwell in Plasma) has been developed to allow complex simulations of multi-species plasma coupled with electromagnetic fields, whether the electromagnetic background is or is not self-consistent with the plasma dynamics. This paper presents the main algorithm of the code and gives several examples of applications.

MOPPC059	Various Approaches to Electromagnetic Field Simulations for RF Cavities	cavity, impedance, electromagnetic-fields, HOM	268
	C. Liu, W. Ackermann, W.F.O. Müller, T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Work supported by BMBF under contract 05H09RD5. The Superconducting Proton Linac (SPL) cavity is mainly designed and conducted by CERN. It is a part of the planned injector upgrade of the Large Hadron Collider (LHC). The SPL cavity is used to accelerate the ion beam from 160 MeV to 5GeV and served as a driver for neutrino facilities and radioactive beam facilities. In the Superconducting Proton Linac (SPL) cavity, it is very important to calculate the eigenmodes precisely, because many higher-order modes (HOMs) can lead to particle beam instabilities. We used and compared three different ways to calculate the eigenmodes in the SPL cavity: field simulation with hexahedron mesh in frequency domain, field simulation with hexahedron mesh in time domain, and field simulation with tetrahedral mesh and higher order curvilinear elements. In this paper the principles of the three numerical methods will be introduced and compared. Finally the calculated results will be presented.

MOPPC063	Computation of the 2D Transverse Wake Function of an Electron Cloud for Different Parameters	electron, 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, electron, 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, electron, cathode, 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	impedance, electron, 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.

MOPPC069	Quantitative Simulation of NIRS-930 Cyclotron	cyclotron, acceleration, extraction, electromagnetic-fields	292
	V.L. Smirnov, S.B. Vorozhtsov JINR/DLNP, Dubna, Moscow region, Russia A. Goto, S. Hojo, T. Honma, K. Katagiri NIRS, Chiba-shi, Japan
	The results of the computer modelling of the structural elements of the NIRS-930 cyclotron operational at the National Institute of Radiological Sciences (Chiba, Japan) are presented. The integrated approach to modelling of the cyclotron, including calculation of electromagnetic fields of the structural elements and beam dynamics simulations is described. A computer model of the cyclotron was constructed. Electric and magnetic field distributions and mechanical structures were converted to the beam dynamics code for simulations, in which particle losses on the surfaces of the system elements were estimated. The existing data on the axial injection, magnetic, acceleration and extraction systems of the cyclotron and beam parameter measurements are used for calibration of the simulations. New acceleration regimes could be formulated with the help of the constructed computer model of the machine.

MOPPC070	Field Emission Simulation for KEK-ERL 9-Cell Superconducting Cavity	cavity, electron, 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.

MOPPC073	Improvements in the PLACET Tracking Code	ground-motion, linac, alignment, multipole	301
	A. Latina, E. Adli, D. Schulte, J. Snuverink CERN, Geneva, Switzerland B. Dalena CEA/IRFU, Gif-sur-Yvette, France
	The tracking code PLACET simulates beam transport and orbit corrections in linear accelerators. It incorporates single- and multi-bunch effects, static and dynamic imperfections. It has an interface based on both Tcl/Tk and Octave to provide maximum flexibility and easy programming of complex scenarios. Recently, new functionality has been added to expand its simulation and tuning capabilities, such as: tools to perform beam-based alignment of non-linear optical systems, possibility to track through the interaction region in presence of external magnetic fields (detector solenoid), higher order imperfections in magnets, better tools for integrated feedback loops. Moreover, self contained frameworks have been created to ease the simulation of CLIC Drive Beam, CLIC Main Beam, and other existing electron machines such as CTF3 and FACET.

MOPPC074	Evolution of MAD-X in the Framework of LHC Upgrade Studies	multipole, optics, luminosity, quadrupole	304
	A. Latina, L. Deniau CERN, Geneva, Switzerland
	The design efforts for the High Luminosity upgrade of the Large Hadron Collider (HL-LHC) will require significant extensions of the MAD-X code widely used for designing and simulating particles accelerators. For this purpose, several new capabilities have been added to the code, namely the possibility to simulate crab cavities for crossing angle compensation, with their imperfections; the selective introduction of thick quadrupole elements for particles tracking, improving the previous implementation entirely based on thin-lenses; and the upgrade of the interface to SixTrack used for distributed tracking with, e.g., LHC@home. These changes are framed into a global redesign of the MAD-X architecture meant to consolidate its structure, improve its performances, and increase its flexibility. Such improvements are described in details in the present paper.

MOPPC075	A Generic Data Model for HeadTail: Design and Implementation with Examples	electron, 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.

MOPPC078	Simulation Studies of Injection Scheme in TPS Storage Ring	injection, lattice, storage-ring, alignment	316
	Y.C. Lee, H.-P. Chang, P.J. Chou NSRRC, Hsinchu, Taiwan
	Funding: NSRRC, Hsinchu, Taiwan. The baseline lattice of TPS storage ring was finalized in October 2009. Later upon users’ request, we plan to implement the double mini-βy lattice in three 12-m straight sections of TPS storage ring. These locations were chosen to maintain the symmetry of the storage ring lattice. Particle tracking for the first few turns were used to check the injection scheme of storage ring, including errors introduced in manufacturing and installation process. Results of simulation studies will be presented.

MOPPC081	Simulation of RF Cavity Dark Current in Presence of Helical Magnetic Field	electron, cavity, 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.

MOPPC082	Beam Dynamics Simulations inProject X RFQ with CST Studio Suite	rfq, acceleration, linac, quadrupole	328
	G.V. Romanov Fermilab, Batavia, USA
	Typically the RFQs are designed using the Parmteq, DesRFQ and other similar specialized codes, which produces the files containing the field and geometrical parameters for every cell. The beam dynamic simulations with these analytical fields are, of course, ideal realizations of the designed RFQs. The new advanced computing capabilities made it possible to simulate beam and even dark current in the realistic 3D electromagnetic fields in the RFQs that may reflect cavity tuning, presence of tuners and couplers, RFQ segmentation etc. The paper describes the utilization of full 3D field distribution obtained with CST Studio Suite for beam dynamic simulations using both PIC solver of CST Particle Studio and the beam dynamic code TRACK.

MOPPC083	LinguaFranca - A Graphical User Interface for Accelerator Modeling	quadrupole, lattice, optics, collider	331
	T.J. Roberts Muons, Inc, Batavia, USA
	This is a proposed project to develop an innovative Graphical User Interface that permits users to construct, explore, optimize, and evaluate accelerator systems efficiently and effectively. While it will be designed with students in mind, accelerator physicists will also find it useful in dealing with the plethora of modeling tools and their different languages. The internal representation of the system is specifically designed to be useable as a text-based description of the system, and to make it easy for users to interface it to essentially any accelerator-modeling tool, regardless of its description language. Many accelerator designers have expressed frustration with the current “Tower of Babel” among modeling programs, and this project will address that directly. In particular, this will make it straightforward to use fast but less realistic programs to design and optimize a system, and then use slower but more realistic programs to evaluate its performance. Graphical interfaces are emphasized, making it easy to construct the system graphically, display the system and its beam, and use on-screen controls to vary parameters and observe their effects immediately.

MOPPC085	An Integrated Green Function Poisson Solver for Rectangular Waveguides	synchrotron, space-charge, beam-beam-effects	337
	R.D. Ryne LBNL, Berkeley, California, USA
	Funding: DOE Office of Science, Office of High Energy Physics and Office of Advanced Scientific Computing Research A new method is presented for solving Poisson's equation inside a rectangular waveguide. The method uses Fast Fourier Transforms (FFTs) to perform mixed convolutions and correlations of the charge density with an integrated Green function. Due to its similarity to the widely used Hockney algorithm for solving Poisson's equation in free space, this capability can be easily implemented in many existing particle-in-cell beam dynamics codes.

MOPPC086	Accelerator Simulation - Beyond High Performance Computing	lattice, target, site, emittance	340
	S. James, G.M. Jung, B.C. Li, K. Muriki, H. Nishimura, Y. Qin, K. Song, C. Sun LBNL, Berkeley, California, USA
	Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. Accelerator modeling and simulation studies heavily rely on High Performance Computing (HPC). Public Cloud computing has opened a new service horizon for HPC by offering an on-demand, Virtual Private Cloud (VPC). Previously, we investigated using Amazon HPC public Cloud for lattice optimization applications and evaluated performance. In this research, we use the Amazon VPC technology to extend local HPC resources to provide a seamless, hybrid, and secure environment when the demand for computing capacity spikes. C. Sun et al., "HPC Cloud Applied to Lattice Optimization," Proc. PAC2011, New York, WEP151, p. 1767 (2011).

MOPPC089	CUDA Kernel Design for GPU-based Beam Dynamics Simulations	acceleration, space-charge, impedance, linac	343
	I.V. Pogorelov, K.M. Amyx, J. Balasalle, J. James Tech-X, Boulder, Colorado, USA M. Borland, R. Soliday, Y. Wang ANL, Argonne, USA
	Funding: Work supported by the US DOE Office of Science, Office of Basic Energy Sciences under grant number DE-SC0004585. Efficient implementation of general-purpose particle tracking on GPUs can result in significant performance benefits to large-scale particle tracking and tracking-based accelerator optimization simulations. We present our work on CUDA kernels for transfer maps of single-particle-dynamics and collective-effects beamline elements, to be incorporated into a GPU-accelerated version of the ANL's accelerator code ELEGANT. In particular, we discuss techniques for efficient utilization of the device shared, cache, and local memory in the design of single-particle and collective-effects kernels. We also discuss the use of data-parallel and hardware-assisted approaches (segmented scan and atomic updates) for resolving memory contention issues at the charge deposition stage of algorithms for modeling collective effects. We present and discuss performance results for the CUDA kernels developed and optimized as part of this project.

MOPPC090	Coupling Modulator Simulations into an FEL Amplifier for Coherent Electron Cooling	FEL, electron, 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).

MOPPC091	Parallel 3D Simulations to Support Commissioning of a Solenoid-based LEBT Test Stand	rfq, solenoid, emittance, cyclotron	349
	B.T. Schwartz, D.T. Abell, D.L. Bruhwiler, Y. Choi, S. Mahalingam, P. Stoltz, J. von Stecher Tech-X, Boulder, Colorado, USA B. Han, M.P. Stockli ORNL, Oak Ridge, Tennessee, USA
	Funding: This work is supported by the US DOE Office of Science, Office of Basic Energy Sciences, including grant No. DE-SC0000844. A solenoid-based low-energy beam transport (LEBT) test stand is under development for the Spallation Neutron Source (SNS). To support commissioning of the test stand, the parallel Vorpal framework is being used for 3D electrostatic particle-in-cell (PIC) simulations of H⁻ beam dynamics in the LEBT, including impact ionization physics and MHz chopping of the partially-neutralized \Hm beam. Here we describe the process of creating a partially-neutralized beam and examine the effects of a single chopping event on the beam's emittance.

MOPPC093	Optimal Fast Multipole Method Data Structures	target, multipole, electron, 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.

MOPPC095	XAL's Online Model at ReA3 to Understand Beam Performance	linac, cavity, cryomodule, lattice	358
	C. Benatti NSCL, East Lansing, Michigan, USA P. Chu, M.J. Syphers, X. Wu FRIB, East Lansing, Michigan, USA
	Funding: This material is based on work supported by the National Science Foundation under Grant No. PHY-1102511 and by Michigan State University. The ReA3 facility at the NSCL at MSU has been designed to reaccelerate rare isotope beams to 3MeV/u. ReA3 consists of a charge to mass selection section, a normal conducting RFQ, a superconducting linac, and transport beam lines that deliver the beam to the experiments. The beam optics designs were developed using COSY and IMPACT. A code with an online model capable of interacting with the control system, such as XAL, developed at SNS, would be ideal for studying this system. New elements have been added to XAL’s already extensive list of supported devices in order to model elements unique to the NSCL. The benchmarking process has been completed for establishing the use of XAL’s Online Model at the NSCL, and preliminary results from its use at the ReA3 control room have been obtained. The development of applications to fit the needs of the program is ongoing. A summary of the benchmarking process is presented including both transverse and longitudinal studies. J. Galambos et al., Proc. PAC 2005, p. 79, (2005); doi: 10.1109/PAC.2005.1590365.

MOPPC096	Multiphysics Applications of ACE3P	HOM, vacuum, cavity, SRF	361
	K.H. Lee, C. Ko, Z. Li, C.-K. Ng, L. Xiao SLAC, Menlo Park, California, USA G. Cheng, H. Wang JLAB, Newport News, Virginia, USA
	Funding: Work supported by US DOE Offices of HEP, ASCR and BES under contract AC02-76SF00515. The TEM3P module of ACE3P, a parallel finite-element electromagnetic code suite from SLAC, focuses on the multiphysics simulation capabilities, including thermal and mechanical analysis for accelerator applications. In this pa- per, thermal analysis of coupler feedthroughs to supercon- ducting rf (SRF) cavities will be presented. For the realistic simulation, internal boundary condition is implemented to capture RF heating effects on the surface shared by a di- electric and a conductor. The multiphysics simulation with TEM3P matched the measurement within 0.4%.

MOPPD003	DITANET - An International Network in Beam Diagnostics	diagnostics, emittance, instrumentation, monitoring	370
	C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: Work supported by the European Union under contract PITN-GA-2008-215080. DITANET is the largest-ever EU funded research and training network in beam diagnostics. It brings together universities, research centers and industry partners to jointly develop diagnostics methods for a wide range of existing or future particle accelerators. This is achieved through a cohesive approach that allows for the exploitation of synergies, whilst promoting knowledge exchange between partners. In addition to its broad research program, the network organizes a large number of international schools and topical workshops for the beam instrumentation and particle accelerator communities. The project comes to an end in May 2012. This contribution presents some of the network's recent research outcomes and training activities.

MOPPD004	oPAC - Optimizing Accelerators through International Collaboration	laser, controls, instrumentation, emittance	373
	C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: Work supported by the European Union under contract PITN-GA-2011-289485. The optimization of the performance of any particle accelerator critically depends on an in-depth understanding of the beam dynamics in the machine and the availability of simulation tools to study and continuously improve all accelerator components. It also requires a complete set of beam diagnostics methods to monitor all important machine and beam parameters with high precision and a powerful control and data acquisition system. Within the oPAC project all these aspects will be closely linked with the aim to optimize the performance of present and future accelerators that lie at the heart of many research infrastructures. The project brings together 22 institutions from around the world. With a project budget of 6 M€, it is one of the largest research and training networks ever funded by the EC. This contribution gives an overview of the network's broad research program and summarizes the training events that will be organized by the consortium within the next 4 years.

MOPPD005	Stochastic Cooling of Antiprotons in the Collector Ring at FAIR	pick-up, antiproton, kicker, ion	376
	C. Dimopoulou, A. Dolinskii, F. Nolden, C. Peschke, M. Steck GSI, Darmstadt, Germany
	In order to reach the required luminosities for the experiments at FAIR, the hot secondary beams (antiprotons or rare isotopes) emerging from the production targets will be efficiently collected and phase-space cooled in the large-acceptance Collector Ring (CR), which is equipped with pertinent stochastic cooling systems. Simulations of the system performance are underway in parallel with the finalization of the system design. After an overview of the CR stochastic cooling systems, simulation results for antiproton cooling in the bandwidth 1-2 GHz are presented. The CERN Fokker-Planck code is used for momentum cooling and an analytical model based on "rms" theory for the simultaneous betatron cooling. In the focus is the comparison between the time of flight and the notch filter momentum cooling methods. The results are essential for system optimization as well as input for the users of the CR-precooled beams i.e. the HESR.

MOPPD012	Challenge for More Efficient Transverse Laser Cooling for Beam Crystallization	laser, synchrotron, ion, betatron	394
	A. Noda, M. Nakao, H. Souda, H. Tongu Kyoto ICR, Uji, Kyoto, Japan M. Grieser MPI-K, Heidelberg, Germany Z.Q. He TUB, Beijing, People's Republic of China K. Ito, H. Okamoto, K. Osaki HU/AdSM, Higashi-Hiroshima, Japan K. Jimbo Kyoto University, Institute for Advanced Energy, Kyoto, Japan Y. Yuri JAEA/TARRI, Gunma-ken, Japan
	Funding: Work supported by Advanced Compact Accelerator Development project by MEXT. Also supported by GCOE project at Kyoto University, The next generation of Physics-Spun from Universality and Emergency. At S-LSR in ICR, Kyoto University, Mg ion beam has been successfully laser cooled both in longitudinal* and transverse** directions. The cooling rate, however, is not strong enough to realize the crystalline beam due to the heating because of intra-beam scattering (IBS) effect. So as to suppress this IBS, reduction of the beam intensity is inevitable, which however, had resulted in poor S/N ratio for observation of the transverse beam size. In the present paper, we would like to describe a new beam scraping scheme, which selects out the beams in the distribution tail of the transverse phase space keeping the beam density in the core part by simultaneous application of multi-dimensional laser cooling and beam scraping. The strategy to reduce the beam intensity and hence beam heating due to IBS by a controlled scraping of the outskirt beam keeping the beam density at core part almost the same, has been searched by combination of the beam experiments and computer simulations. * M. Tanabe et al., Applied Physics Express 1, 028001 (2008). ** M. Nakao et al., submitted to PRST-AB.

MOPPD021	An Experimental Investigation of Slow Integer Tune Crossing in the EMMA Non-scaling FFAG	acceleration, resonance, closed-orbit, proton	412
	J.M. Garland, H.L. Owen UMAN, Manchester, United Kingdom D.J. Kelliher, S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom B.D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Funding: Student STFC grant number: ST/G004277/1. Results are presented from a slow integer tune crossing experiment performed in the EMMA accelerator. Under nominal conditions EMMA accelerates an electron beam from 10–20 MeV rapidly in 5–10 turns in a novel “serpentine” channel causing several transverse integer tunes to be crossed. During this rapid acceleration it has been shown that the betatron amplitude of the beam does not grow. If the potential of non-scaling FFAGs were to be realized in such fields as high-current proton acceleration then tune space would be crossed slower with acceleration in an RF bucket. The crossing speed in a non-scaling FFAG is in a previously unstudied intermediate region and hence conventional crossing theory may not apply. It was proposed to observe the effects on betatron amplitude when a beam crosses integer tunes by the variation of tune with momentum over a range of crossing speeds derived from different acceleration rates. This method can be realized by synchrotron acceleration inside a stable RF bucket. Betatron amplitude growth and beam loss as a function of turn are explored when crossing an integer tune and a relationship between crossing speed and these quantities is established.

MOPPD023	Correction of the nu_r=3/2 Resonance in TRIUMF Cyclotron	resonance, cyclotron, TRIUMF, extraction	415
	T. Planche, R.A. Baartman, Y.-N. Rao TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	Imperfections in the TRIUMF cyclotron are a source of field errors which slightly violate the 6-fold symmetry of the ring. Among them, the third harmonic of the magnetic gradient errors drives the ν_r=3/2 resonance. This results in a modulation of the current density versus radius observed after the resonance crossing all the way to the extraction (480 MeV). The cyclotron has sets of harmonic correction coils at different radii, each set constituted of 6 pairs of coils placed in a 6-fold symmetrical manner. The 6-fold symmetry of this layout makes that a single set of harmonic coils cannot provide a full correction of third harmonic errors driving the ν_r=3/2 resonance. The last two sets of harmonic correction coils (number 12 and 13) are azimuthally displaced. In this study, we use this fact to achieve a full correction of the resonance. We also present experimental measurements that demonstrate the full correction.

MOPPD024	C70 Arronax in the Hands-On Phase	target, cyclotron, proton, injection	418
	F. Poirier, S. Auduc, L. Lamouric SUBATECH, Nantes, France S. Girault, F. Gomez, E. Mace Cyclotron ARRONAX, Saint-Herblain, France C. Huet EMN, Nantes, France
	The C70 Arronax, is a high-intensity (2x375 μA) and high-energy (70 MeV) multiparticle cyclotron that started its hands-on phase in December 2010. The operating and maintenance group is accumulating experience on this machine. A review of the machine status and present possibilities in terms of beam capacities is thus presented in this paper. The status of the beamline simulations is also given.

MOPPD027	A Compact High Intensity Cyclotron Injector for DAEδALUS Experiment	extraction, cyclotron, resonance, beam-losses	424
	L. Calabretta, D. Rifuggiato INFN/LNS, Catania, Italy A. Adelmann Paul Scherrer Institut, Villigen, Switzerland A. Calanna, D. Campo CSFNSM, Catania, Italy M.M. Maggiore, L.A.C. Piazza INFN/LNL, Legnaro (PD), Italy J.J. Yang CIAE, Beijing, People's Republic of China
	Funding: Istituto Nazionale di Fisica Nucleare - Laboratori Nazionale del Sud. The experiment DAEδALUS, recently proposed by MIT scientist to search for CP violation in the neutrino sector, needs three accelerator with energy of about 800 MeV, average power of some MW and duty cycle of 20%. To reduce the cost of the accelerators a cyclotron complex consisting of an injector and of a booster ring cyclotron has been proposed. The main characteristics of the new kind of separated sector cyclotron injector able to accelerate a H²⁺ molecule beam up to 60 MeV/n will be presented. Due to the low duty cycle, the peak current to be accelerated is 5 mA. The problem related to the injection of a H²⁺ beam, delivered by a compact ion source, and to the space charge effects will be discussed. To allow an easier injection in the booster Superconducting Ring Cyclotron the extraction energy has been increased up to 60 MeV/n. The pole gap was decreased to 60 mm to achieve a more efficient beam extraction. The updated configuration of the magnetic sectors, of the isochronous magnetic field and beam dynamics along extraction path and during the acceleration will be presented, too. J. Alonso et al., "Novel Search for CP Violation in the Neutrino Sector: DAEδALUS," Jun2010 e-Print: arXiv:1006.0260 ** L. Calabretta, Proc. of IPAC 2011, WEPS073, p. 2673 (2011).

MOPPD028	Observation of Longitudinal Space Charge Effects in the Injection Beam Line of NIRS-930 Cyclotron	bunching, cyclotron, space-charge, injection	427
	S. Hojo, A. Goto, T. Honma, K. Katagiri, A. Sugiura NIRS, Chiba-shi, Japan
	Dependence of bunching efficiencies on the position of a beam buncher was measured for the AVF cyclotron at the National Institute of Radiological Sciences (NIRS) for 30 MeV proton beams with intensities up to 100 microamperes at injection. The measurement was carried out for two positions: 1.53 m and 2.33 m upstream from the inflector. For the buncher position of 2.33 m the bunching efficiency decreased, as the beam intensity increased, to about half of that at low intensities, while for 1.5 m it was constant up to 100 microamperes. The intensity distributions of extracted beam with respect to the buncher phase were also measured for the two buncher positions. The dependence of bunch width on the beam intensity is discussed by comparing the data with one-dimensional simulations on longitudinal space charge effects.

MOPPD044	Optimization of the Target Subsystem for the New g-2 Experiment	target, proton, focusing, factory	460
	C. Y. Yoshikawa, C.M. Ankenbrandt Muons, Inc, Batavia, USA A.F. Leveling, N.V. Mokhov, J.P. Morgan, D.V. Neuffer, S.I. Striganov Fermilab, Batavia, USA
	A precision measurement of the muon anomalous magnetic moment, aμ = (g-2)/2, was previously performed at BNL with a result of 2.2 - 2.7 standard deviations above the Standard Model (SM) theoretical calculations. The same experimental apparatus is being planned to run in the new Muon Campus at Fermilab, where the muon beam is expected to have less pion contamination and the extended dataset may provide a possible 7.5σ deviation from the SM, creating a sensitive and complementary benchmark for proposed SM extensions. We report here on a preliminary study of the target subsystem where the apparatus is optimized for pions that have favorable phase space to create polarized daughter muons around the magic momentum of 3.094 GeV/c, which is needed by the downstream g 2 muon ring.

MOPPD054	Effect of the 2011 Great East Japan Earthquake in the Injection and Extraction of the J-PARC 3-GeV RCS	injection, extraction, septum, beam-transport	490
	P.K. Saha, H. Harada, H. Hotchi, S.I. Meigo, N. Tani, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	In the 3-GeV rapid cycling synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC), the injection and extraction systems play important roles for the beam injection and extraction, respectively. Unfortunately, the 2011 great east Japan earthquake had a serious impact on the ongoing schedule due to the big damage of the whole accelerator facility and the infrastructure as well. The injection and extraction including the beam transport lines magnets suffered a noticeable displacement resulting with alignment errors. As realignment of the RCS magnets can not be done in this year, then based on the post earthquake measured alignment data, we have estimated the effect as well as possible solutions on the injected and extracted beam for as usual operation. Fortunately, the simulation results shows that there would not be any serious impact on both injected as well as extracted beam with present alignment errors and thus user operation can be resume as expected. The simulation result together with some experimental results will be presented.

MOPPD061	LHC@home: a Volunteer Computing System for Massive Numerical Simulations of Beam Dynamics and High Energy Physics Events	HOM, collider, controls, superconducting-magnet	505
	M. Giovannozzi, F. Grey, A. Harutyunyan, N. Hoimyr, P.L. Jones, A. Karneyeu, M.A. Marquina, E. McIntosh, B. Segal, P. Skands CERN, Geneva, Switzerland D. Lombraña González CCC, 1211Geneva 23, Switzerland L. Rivkin, I. Zacharov EPFL, Lausanne, Switzerland
	Recently, the LHC@home system has been revived at CERN. It is a volunteer computing system based on BOINC which allows boosting the available CPU-power in institutional computer centers by the help of individuals that donate the CPU-time of their PCs. Currently two projects are hosted on the system, namely SixTrack and Test4Theory. The first is aimed at performing beam dynamics simulations, while the latter deals with the simulation of high-energy events. In this paper the details of the global system, as well a discussion of the capabilities of either project will be presented. Milestones of progress of the projects will also be discussed.

MOPPD063	A 180 MeV Injection System for the ISIS Synchrotron	injection, dipole, synchrotron, electron	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.

MOPPD064	Simulation of Double Layer Carbon Stripping Foils for ISIS Injection Upgrades	injection, radiation, scattering, proton	514
	H. V. Smith, D.J. Adams, B. Jones, C.M. Warsop STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom Y. Irie, Y. Takeda KEK, Ibaraki, Japan
	ISIS, the pulsed neutron and muon spallation source located at the Rutherford Appleton Laboratory (UK), currently delivers a mean beam power of 0.2 MW to target. A 70 MeV H linear accelerator feeds into a 50 Hz, 800 MeV proton synchrotron, accelerating up to 3·10¹³ protons per pulse. Potential injection scheme upgrades, aiming to raise average beam power towards 0.5 MW with a new 180 MeV linear accelerator, continue to be studied. This paper highlights recent results from temperature studies of double layer carbon foils, suitable for injection at 180 MeV into ISIS, using ANSYS. Experimental data from KEK was used to benchmark models and the variation of temperature as a function of foil separation was considered.

MOPPD073	Development of Transportation System for Low Energy Electron Group	electron, solenoid, collimation, 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.

MOPPD074	Localization of Large Angle Foil Scattering Beam Loss Caused by Multi-Turn Charge-Exchange Injection	collimation, injection, scattering, insertion	535
	S. Kato Tohoku University, Graduate School of Science, Sendai, Japan H. Harada, S. Hatakeyama, J. Kamiya, M. Kinsho, K. Yamamoto, Y. Yamazaki, M. Yoshimoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	In the J-PARC RCS, the significant losses were observed at the branch of H⁰ dump line and the Beam Position Monitor which was put at the downstream of the H⁰ dump branch duct. These losses were caused by the large angle scattering of the injection and circulating beam at the charge exchange foil. To realize high power operation, we have to mitigate these losses. So, we started to develop a new collimation system in the H⁰ branch duct and installed in October 2011. In order to optimize this system efficiently, we primarily focused on the relative angle of collimator block from scattering particles. We simulated behavior of particles scattered by foil and produced by collimator block and researched most optimized position and angle of the collimator block. In this process, we devised the method of angular regulation of collimator block. We present the method of angular regulation and performance of this new collimation system.

MOPPD076	Numerical Study of a Collimation System to Mitigate Beam Losses in the ESS Linac	linac, DTL, beam-losses, collimation	541
	R. Miyamoto, H. Danared, M. Eshraqi, A. Ponton ESS, Lund, Sweden
	The European Spallation Source (ESS) will be a 5 MW proton linac to produce spallation neutrons. A high power linac has a very low tolerance on beam losses, typically on the order of 1 W/m, to avoid activation of the linac components; hence, emittance and halo of the beam must be well controlled throughout the linac. A system of collimators in beam transport sections has been studied and tested as a means to mitigate the beam losses in several linacs. This paper presents the result of a numerical study of a collimation system for the ESS linac.

MOPPD078	Accelerator Physics Study on the Effects from an Asynchronous Beam Dump in the LHC Experimental Region Collimators	proton, kicker, betatron, optics	547
	L. Lari, R.W. Assmann, V. Boccone, R. Bruce, F. Cerutti, A. Mereghetti, A. Rossi, V. Vlachoudis CERN, Geneva, Switzerland A. Faus-Golfe, L. Lari IFIC, Valencia, Spain
	Funding: This work has been carried out through of the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program. Asynchronous beam aborts at the LHC are to be expected once per year. Accelerator physics studies of asynchronous dumps have been performed at different beam energies and beta-stars. The loss patterns are analyzed in order to identify the losses in particular on the Phase 1 Tertiary Collimators (TCT), since their Tungsten jaw insert has a low damage threshold with respect to the loss load expected. Settings for the tilt angle of the TCTs are discussed with the aim of reducing the thermal loads on the TCT themselves.

MOPPD079	Preliminary Thermo-Mechanical Analysis of Angular Beam Impact on LHC Collimators	collimation, kicker, superconducting-magnet, controls	550
	M. Cauchi, R.W. Assmann, A. Bertarelli, F. Carra, A. Dallocchio, D. Deboy, N. Mariani, A. Rossi CERN, Geneva, Switzerland L. Lari IFIC, Valencia, Spain P. Mollicone UoM, Msida, Malta N.J. Sammut University of Malta, Faculty of Engineering, Msida, Malta
	Funding: This work is supported by EuCARD. The correct functioning of the LHC collimation system is crucial to attain the desired LHC luminosity performance. However, the requirements to handle high intensity beams can be demanding. In this respect, accident scenarios must be well studied in order to assess if the collimator design is robust against likely error scenarios. One of the catastrophic - though not very probable - accident scenarios identified is an asynchronous beam dump coupled with slight angular misalignment errors of the collimator jaw. Previous work presented a preliminary thermal evaluation of the extent of beam-induced damage for such scenarios, where it was shown that in some cases, a tilt of the jaw could actually serve to mitigate the effect of an asynchronous dump on the collimators. This paper will further analyze the response of tertiary collimators in presence of such angular jaw alignments, with the aim to identify optimal operational conditions.

MOPPD081	Upgrade of the LHC Beam Dumping Protection Elements	extraction, kicker, dumping, vacuum	556
	W.J.M. Weterings, T. Antonakakis, B. Balhan, J. Borburgh, B. Goddard, C. Maglioni, R. Versaci CERN, Geneva, Switzerland
	The Beam Dumping System for the Large Hadron Collider comprises for each ring a set of horizontally deflecting extraction kicker magnets, vertically deflecting steel septa, dilution kickers and finally, a couple of hundred meters further downstream, an absorber block. A mobile diluter (TCDQ) protects the superconducting quadrupole immediately downstream of the extraction as well as the arc at injection energy and the triplet aperture at top energy from bunches with small impact parameters, in case of a beam dump that is not synchronized with the particle free gap or a spontaneous firing of the extraction kickers. Simulations have shown that an asynchronous dump of a 7 TeV nominal beam into the TCDQ absorber blocks could damage it. This paper describes the proposed changes to this device in order to maintain the protection for the downstream elements while reducing the risk of damaging the TCDQ in case of such a beam loss.

MOPPP004	Further Study on Fast Cooling in Compton Storage Rings	laser, electron, storage-ring, 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, electron, 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.

MOPPP009	X-Ray Spectra Reconstruction of Thomson Scattering Source From Analysis of Attenuation Data	scattering, photon, target, laser	586
	Y.-C. Du, Hua, J.F. Hua, W.-H. Huang, C.-X. Tang, H.S. Xu, L.X. Yan, H. Zha, Z. Zhang TUB, Beijing, People's Republic of China
	Thomson scattering X-ray source, in which the TW laser pulse is scattered by the relativistic electron beam, can provide ultra short, monochromatic, high flux, tunable polarized hard X-ray pulse which is can widely used in physical, chemical and biological process research, ultra-fast phase contrast imaging, and so on. Since the pulse duration of X-ray is as short as picosecond and the flux in one pulse is high, it is difficult to measure the x-ray spectrum. In this paper, we present the X-ray spectrum measurement experiment on Tsinghua Thomson scattering. The preliminary experimental results shows the maximum X-ray energy is about 47 keV, which is agree well with the simulations.

MOPPP010	Investigation of CSR Effect for Femtosecond Electron Bunches in an Isochronous Accumulator Ring	lattice, radiation, electron, 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	electron, laser, 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, electron, dipole, 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).

MOPPP021	Longitudinal Beam Dynamics at the ALICE Acclerator R&D Facility	booster, linac, gun, FEL	610
	F. Jackson, D. Angal-Kalinin, S.P. Jamison, J.W. McKenzie, T.T. Ng, Y.M. Saveliev, P.H. Williams STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The ALICE facility is an energy recovery test accelerator whose applications include an IR-FEL and THz generation. Of primary importance to the performance of the main ALICE applications is the understanding and control of the longitudinal dynamics, which are less amenable to measurement than the transverse. The longitudinal dynamics of the beam evolve are studied in simulation and experiment in several areas of the machine. Simulations of the low energy injector where space charge and velocity bunching may occur are presented. Path length measurement using time-of-arrival monitors are carried out.

MOPPP034	Simulation of the Longitudinal Phase Space Measurement with Transverse Deflecting Structure at PITZ	cavity, electron, dipole, emittance	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.

MOPPP036	Progress in Reducing the Back-bombardment Effect in the ITC-RF gun for t-ACTS Project at Tohoku University	cathode, electron, gun, dipole	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

MOPPP050	Physics Results of the NSLS-II Linac Front End Test Stand	linac, emittance, gun, electron	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.

MOPPP053	Failure Mode Analysis in Preparation for Top-up Injection at the Canadian Light Source (CLS)	injection, storage-ring, dipole, kicker	682
	L.O. Dallin CLS, Saskatoon, Saskatchewan, Canada
	Top-up injection involves injecting beam with beamline safety shutters open. Consequently it is extremely important that no electrons enter the beamlines where they could be a potential safety hazard to beamline personnel. To investigate the likelihood that electrons could exit the storage ring various failure mode simulations have been done. The approach is to account for all possible injection trajectories and show that these particles will be intercepted by various storage ring apertures before they reach an amplitude that is deemed unsafe. This amplitude was chosen to be 50 mm and the field roll-off of all storage ring magnets were defined to this amplitude. Failure modes invested included injection kicker failures, uncorrected misalignment errors, off-energy injection and shorted storage ring magnet coils. Errors that would render it impossible to store beam were not investigated. As some particles reached amplitudes beyond the safe limit measures have been devised to eliminate these unsafe scenarios.

MOPPP065	Effects of Geometrical Errors on the Field Quality in a Planar Superconducting Undulator	undulator, photon, status, electron	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	electron, undulator, vacuum, storage-ring	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.

MOPPP086	Praseodymium Iron-Boron Undulator With Textured Dysprosium Poles for Compact X-Ray FEL Applications	undulator, cryogenics, insertion, insertion-device	756
	R.B. Agustsson, Y.C. Chen, T.J. Grandsaert, A.Y. Murokh RadiaBeam, Santa Monica, USA F.H. O'Shea UCLA, Los Angeles, California, USA V. Solovyov BNL, Upton, Long Island, New York, USA
	Funding: DOE SBIR #97134S11-I Radiabeam Technologies is developing a novel ultra-high field short period undulator using two unconventional materials: praseodymium permanent magnets (PrFeB) and textured dysprosium (Tx Dy) ferromagnetic field concentrators. Both materials exhibit extraordinary magnetic properties at cryogenic temperatures, such as very large energy product and record high induction saturation, respectively. The proposed device combines PrFeB and Tx Dy in 3-D hybrid undulator geometry with sub-cm period and up to 3 Tesla pole tip field. Practical realization of these features will significantly surpass state-of-the-art and offer an ideal solution for the next generation of compact X-ray light sources. Initial simulations along with preliminary cryogenic measurements will be presented.

MOPPR007	Investigation of Techniques for Precise Compton Polarimetry at ELSA	electron, polarization, photon, laser	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.

MOPPR034	A Laser Wire System at Electron Beam Transport Line in BEPCII	laser, electron, photon, positron	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, electron, factory	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.

MOPPR042	Characterization Tests of a Stripline Beam Position Monitor for the CLIC Drive Beam	impedance, quadrupole, extraction, feedback	873
	A. Benot-Morell, A. Faus-Golfe, J.J. García-Garrigós IFIC, Valencia, Spain A. Benot-Morell, L. Søby CERN, Geneva, Switzerland J.M. Nappa, J. Tassan-Viol, S. Vilalte IN2P3-LAPP, Annecy-le-Vieux, France S.R. Smith SLAC, Menlo Park, California, USA
	Funding: FPA2010-21456-C02-01, SEIC-2010-00028 A prototype of a stripline Beam Position Monitor (BPM) with its associated readout electronics has been developed at CERN in collaboration with SLAC, LAPP and IFIC. In this paper, the design and simulations of the BPM with the analog readout chain and the BPM test bench are described, and the results of the first characterization tests are presented. The position resolution and accuracy parameters are expected to be below 2μm and 20μm respectively for a beam with a bunching frequency of 12GHz, an average current of 101A and a machine repetition rate of 50Hz.

MOPPR046	CLIC Luminosity Monitoring	photon, luminosity, monitoring, background	885
	A. Apyan, L.C. Deacon, E. Gschwendtner, T. Lefèvre CERN, Geneva, Switzerland R. Appleby, S.C. Tygier UMAN, Manchester, United Kingdom
	The CLIC post-collision line is designed to transport the un-collided beams and the products of the collided beams with a total power of 14MW to the main beam dump. Luminosity monitoring for CLIC is based on high energy muons produced by bremsstrahlung photons in the main dump. Threshold Cherenkov counters are proposed for the detection of these muons. The expected rates and layout for these detectors is presented. Another method for luminosity monitoring is to directly detecting the bremsstrahlung photons in the post-collision line; Full Monte Carlo simulation has been performed to address its feasibility.

MOPPR060	Calibration of the EMMA Beam Position Monitors: Position, Charge and Accuracy	pick-up, injection, quadrupole, diagnostics	921
	I.W. Kirkman The University of Liverpool, Liverpool, United Kingdom J.S. Berg BNL, Upton, Long Island, New York, USA G. Cox STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom A. Kalinin STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom D.J. Kelliher, S. Machida STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
	The accurate determination of transverse beam position is essential to understanding the performance of an accelerator system, and this is particularly the case with non-scaling FFAG machines such as EMMA, where, due to fundamental principles of design, the beam may deviate widely from the central beampipe axis. This paper describes the various modelling approaches taken for the three different button pickup assemblies used in EMMA, and the subsequent methods of calibration (‘mappings’) which allow beam position and charge to be deduced from the processed BPM signals. The use and validity of the modelling and mapping approach adopted is described, and the contributions to positional and bunch charge uncertainty arising from these procedures is discussed.

MOPPR063	Exploiting the Undesired: Beam-gas Interactions in the LHC	vacuum, radiation, proton, quadrupole	927
	R. Versaci, V. Baglin, M. Brugger CERN, Geneva, Switzerland A. Mereghetti UMAN, Manchester, United Kingdom
	The vacuum inside the LHC pipes has a key role in correct operation of the accelerator. The interaction of the beam with residual gas in the pipes can lead to the loss of the beam itself and damage accelerator components. Nevertheless, beam-gas interactions can be exploited to indirectly measure the gas pressure inside the beam pipe, detecting the secondaries produced. The showers generated are detected by Beam Loss Monitors, whose signals depend on the gas pressure. This technique would also allow to punctually measure the gas pressure in sections of the accelerator where vacuum gauges are not frequent, such as the arcs. The problem has been addressed by means of FLUKA simulations and the results have been benchmarked with direct measurements performed in the LHC in 2011.

MOPPR066	Study of Transverse Pulse-to-Pulse Orbit Jitter at the KEK Accelerator Test Facility 2 (ATF2)	extraction, feedback, controls, linear-collider	936
	J. Resta-López, J. Alabau-Gonzalvo IFIC, Valencia, Spain R. Apsimon, B. Constance, A. Gerbershagen CERN, Geneva, Switzerland D.R. Bett, P. Burrows, G.B. Christian, M.R. Davis, C. Perry JAI, Oxford, United Kingdom
	Funding: FPA2010-21456-C02-01 For future linear colliders the precise control and mitigation of pulse-to-pulse orbit jitter will be very important to achieve the required luminosity. Diagnostic techniques for the orbit jitter measurement and correction for multi-bunch operation are being addressed at the KEK Accelerator Test Facility 2 (ATF2). In this paper we present recent studies on the vertical jitter propagation through the ATF2 extraction line and final focus system. For these studies the vertical pulse-to-pulse position and angle jitter have been measured using the available stripline beam position monitors in the beamline. The cases with and without intra-train orbit feedback correction in the ATF2 extraction line are compared.

MOPPR067	Simulations of Fast X-ray Detectors Based on Multichannel Plates	electron, photon, 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.

MOPPR069	Use of Waveguide and Beam Pipe Probes as Beam Position and Tilt Monitoring Diagnostics with Superconducting Deflecting Cavities	cavity, dipole, HOM, monitoring	945
	X. Sun, T.G. Berenc, G. Decker, G.J. Waldschmidt, G. Wu 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. Waveguide and beam pipe field probes associated with a superconducting deflecting cavity are explored as beam position and tilt monitoring diagnostics. The superconducting deflecting cavity will be used for the Short-pulse X-rays (SPX) in the Advanced Photon Source (APS) upgrade project. Microwave Studio will be used to simulate the techniques of detecting the fields excited by the beam passing through the cavity and determining how close the beam is on electrical center.

MOPPR074	Using TE Wave Resonances for the Measurement of Electron Cloud Density	resonance, cavity, electron, 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.

MOPPR077	ION CHAMBERS AND HALO RINGS FOR LOSS DETECTION AT FRIB	radiation, ion, linac, cryomodule	969
	Z. Liu IUCF, Bloomington, Indiana, USA D. Georgobiani, M.J. Johnson, M. Leitner, R.M. Ronningen, T. Russo, M. Shuptar, R.C. Webber, J. Wei, X. Wu, Y. Yamazaki, Y. Zhang, Q. Zhao FRIB, East Lansing, Michigan, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661. Unlike the high energy proton machines, our radiation transport simulation results show that it will be difficult to use traditional BLMs to detect beam losses for FRIB linac, not only due to the low radiation levels from low energy heavy ion beams, but also resulted by the cross talk effect from one part of the machine to another in the folded machine geometry. A device called “Halo Ring” is introduced as a component of the BLM system to substitute the traditional ion chamber in those regions.

MOPPR092	SVD-BASED METHOD FOR MEASUREMENT OF BEAM PARAMETERS AND FLAG RESOLUTION	emittance, quadrupole, booster, focusing	999
	G.M. Wang, R.P. Fliller, I. Pinayev, T.V. Shaftan BNL, Upton, Long Island, New York, USA
	In NSLS II booster to storage ring transport line, the typical beam size in vertical plane is ~60 μm, which requires very high flag resolution to get good beam parameters measurement. This paper describes a new SVD-based method to measure transverse beam parameters and flag resolution simultaneously with double quads scan. Implementation simulations of the proposed method are performed for a dispersion free region in the NSLS-II booster to storage ring transport line. With this method, it breaks the limitation of beam parameters measurement accuracy duo to the flag resolution.

TUOAA01	3-Dimensional Modeling of Electron Clouds in Non-uniform Magnetic Fields	plasma, electron, wiggler, 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]

TUOBC02	Small-Beta Collimation at SuperKEKB to Stop Beam-Gas Scattered Particles and to Avoid Transverse Mode Coupling Instability	interaction-region, impedance, scattering, coupling	1104
	H. Nakayama, Y. Funakoshi, K. Kanazawa, K. Ohmi, Y. Ohnishi, Y. Suetsugu KEK, Tsukuba, Japan H. Nakano Tohoku University, Graduate School of Science, Sendai, Japan
	At SuperKEKB, beam particles which are Coulomb-scattered by the residual gas molecular change direction and will be eventually lost by hitting beam pipe inner wall. Due to large vertical beta function and small beam pipe radius just before IP, most of Coulomb-scattered particles are lost there and are very dangerous for the Belle-II detector. To stop such particles before the IP, vertical collimators are installed in the ring. However, such vertical collimators should be placed very close (few mm) to the beam and therefore induce transverse mode coupling instability. To avoid beam instability and achieve collimation at the same time, we need to install vertical collimators where vertical beta function is SMALL, since maximum collimator width determined by aperture condition is proportional to β^1/2, and minimum collimator width determined by instability is proportional to β^2/3. We present our strategy to stop beam-gas scattered particles and simulated loss rate in the interaction region. We will also show dedicated vertical collimator design to achieve less instability.
	Slides TUOBC02 [2.196 MB]

TUEPPB001	Interaction of Muon Beam with Plasma Developed During Ionization Cooling	plasma, wakefield, electron, 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	electron, 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

TUEPPB003	Nonlinear Accelerator with Transverse Motion Integrable in Normalized Polar Coordinates	lattice, focusing, insertion, damping	1116
	T.V. Zolkin University of Chicago, Chicago, Illinois, USA Y. Kharkov, I.A. Morozov BINP SB RAS, Novosibirsk, Russia S. Nagaitsev Fermilab, Batavia, USA
	Several families of nonlinear accelerator lattices with integrable transverse motion were suggested recently. One of the requirements for the existence of two analytic invariants is a special longitudinal coordinate dependence of fields. This paper presents the particle motion analysis when a problem becomes integrable in the normalized polar coordinates. This case is distinguished from the others: it yields an exact analytical solution and has a uniform longitudinal coordinate dependence of the fields (since the corresponding nonlinear potential is invariant under the transformation from the Cartesian to the normalized coordinates). A number of interesting features are revealed: while the frequency of radial oscillations is independent of the amplitude, the spread of angular frequencies in a beam is absolute. A corresponding spread of frequencies of oscillations in the Cartesian coordinates is evaluated via the simulation of transverse Schottky noise. V. Danilov and S. Nagaitsev, Phys. Rev. ST Accel. Beams 13 084002 (2010).*

TUEPPB004	A Longitudinal Beam Dynamics Code for Proton Synchrotron	cavity, space-charge, synchrotron, bunching	1119
	Y.S. Yuan, N. Wang, S. Wang, S.Y. Xu IHEP, Beijing, People's Republic of China
	The accelerator of China Spallation Neutron Source (CSNS) consists of an 80 MeV linac and a 1.6 GeV Rapid Cycling Synchrotron (RCS). Longitudinal beam dynamics study is one of the most important issues for RCS beam dynamics design. However, the existing codes cannot meet the requirement of longitudinal beam dynamics for CSNS/RCS. A new code has been developed for longitudinal beam dynamics design and simulation. The code can perform the voltage and phase curves design for non-sinusoidal magnetic field of dipole in an RCS cycle, with the fundamental RF mode and dual harmonic mode. The code can also be used for the beam simulation with longitudinal space charge effect, including the effects of higher order mode of RF cavities. By using the code, the longitudinal beam dynamics of CSNS/RCS was designed and optimized, and the simulation study with dual harmonics higher order modes of RF cavity was done, and the simulation results are presented.

TUEPPB006	Direct Numerical Modeling of E-Cloud Driven Instability of Three Consecutive Batches in the CERN SPS	electron, 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.

TUEPPB007	A Self Consistent Multiprocessor Space Charge Algorithm that is Almost Embarrassingly Parallel	space-charge, factory, collective-effects, brightness	1128
	E.W. Nissen JLAB, Newport News, Virginia, USA B. Erdelyi Northern Illinois University, DeKalb, Illinois, USA S.L. Manikonda ANL, Argonne, USA
	Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. We present a space charge code that is self consistent, massively parallelizeable, and requires very little communication between the computer nodes; making the calculation almost embarrassingly parallel. This method is implemented in the code COSY Infinity where the differential algebras used in this code are important to the algorithm's proper functioning. The method works by calculating the self consistent charge distribution using the statistical moments of the test particles, and converting them into polynomial series coefficients. These coefficients are combined with differential algebraic integrals to form the potential, and electric fields. The result is a transfer map which contains the effects of space charge. This method allows for massive parallelization since its statistics based solver doesn’t require any binning of the particles, and only requires a vector containing the partial sums of the statistical moments for the different nodes to be passed. All other calculations are done independently. The resulting maps can be used to analyze the system using normal form analysis, as well as advance particles in numbers and at speeds that were previously impossible.

TUEPPB013	Development of an Advanced Computational Tool for Start-to-End Modeling of Next Generation Light Sources	electron, radiation, 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.

TUPPC006	CW Energy Upgrade of the Superconducting Electron Accelerator S-DALINAC	recirculation, dipole, linac, extraction	1161
	M. Kleinmann, J. Conrad, R. Eichhorn, F. Hug, N. Pietralla TU Darmstadt, Darmstadt, Germany
	Funding: This work is supported by the DFG through SFB 634. The S-DALINAC is a superconducting recirculating electron accelerator with maximum design energy of 130 MeV operating in cw at 3 GHz. Even so the gradients of the superconducting cavities are well above design, their design quality factor of 3*10⁹ have not been reached so far. Due to the limited cooling power of the cryo-plant being 120 W, the final energy achievable in cw operation is around 85 MeV, currently. In order to provide a cw beam with the designed final energy in the future, the installation of an additional recirculation path is projected and to be finished by 2013. We review the design constraints related to the existing beam lines, report in detail on the magnet design (being the key issue) and the lattice calculations for the additional recirculation path.

TUPPC011	Beam Steering Correction in FRIB Quarter-wave Resonators	cavity, linac, cryomodule, solenoid	1176
	A. Facco INFN/LNL, Legnaro (PD), Italy A. Facco, Y. Xu, Y. Zhang, Q. Zhao, Z. Zheng FRIB, East Lansing, Michigan, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 The Quarter-Wave Resonators (QWR) section of the FRIB superconducting driver linac is required to accelerate Uranium beam up to 16 MeV/u in two different charge states simultaneously. This puts severe requirements on resonators alignment and field quality, in order to avoid beam losses and emittance growth. In particular, QWR beam steering can cause transverse oscillations of the beam centroid which reduce the linac acceptance and induces emittance growth. We have studied, with an analytical model and with 3D beam dynamics simulations, correction methods for the FRIB QWRs steering. We found that cavity shifting can provide effective steering cancellation in FRIB QWRs without need of cavity shape modifications, and allows to eliminate transverse beam oscillations and to improve beam quality. Calculation and simulation methods and results will be presented and discussed. Michigan State University designs and establishes FRIB as a DOE Office of Science National User Facility in support of the mission of the Office of Nuclear Physics.

TUPPC019	Beam Dynamics Simulations of J-PARC Main Ring for Damage Recovery from the Tohoku Earthquake in Japan and Upgrade Plan of Fast Extraction Operation	alignment, injection, acceleration, linac	1200
	Y. Sato, K. Hara, S. Igarashi, T. Koseki, K. Ohmi, C. Ohmori KEK, Ibaraki, Japan H. Hotchi JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	Magnets of Japan Proton Accelerator Research Complex (J-PARC) were shaken by the Tohoku Earthquake in Japan on March 11th, 2011. The alignment of J-PARC Main Ring (MR) received 20 mm displacement horizontally and 6 mm vertically. Beam dynamics simulations were performed to estimate the effect of the displacement on closed orbit distortions and beam loss in fast extraction (FX) operation of J-PARC MR. Based on the simulation results, we concluded that re-alignment of J-PARC MR was needed to achieve high-power beam. The re-alignment of MR was finished on October 28th, 2011. We also considered the effects of the earthquake on the upstream of MR to establish our upgrade plan, which was based on beam dynamics simulations optimizing collimator balance of injection beam transport (3-50BT) and MR, and RF patterns. J-PARC MR FX operation was resumed from December 2011.

TUPPC020	A Scheme for Horizontal-vertical Coupling Correction at SuperKEKB	coupling, optics, lattice, target	1203
	H. Sugimoto, H. Koiso, A. Morita, Y. Ohnishi, K. Oide KEK, Ibaraki, Japan
	SuperKEKB is an 7 GeV electron and 4 GeV positron double ring collider project based on the nano beam scheme and is aimed to break the world's luminosity record. A horizontal flat beam is essential to realize the nano beam collisions. One of critical effect that induces unexpected coupling is machine error, such as magnet misalignment and field imperfection. Coupling correction, therefore, plays key role in the actual beam operation. In this study, we numerically explore a possible scheme for coupling correction in the SuperKEKB lattice. Some coupling measurement and correction methods are applied to the model lattice considering magnet misalignments and finite BPM resolution. Based on the results, the attainable smallest coupling in the actual SuperKEKB is discussed.

TUPPC021	Design Study on KEK Injector Linac Upgrade for High-current and Low-emittance Beams	emittance, linac, wakefield, acceleration	1206
	H. Sugimoto, M. Satoh, M. Yoshida KEK, Ibaraki, Japan
	Injector linac at KEK is now under upgrading to produce high current (5nC for e-, 4nC for e+) and low emittance (20 mm mrad for e-, 6 mm mrad for e+) electron and positron beams to a SuperB collider called SuperKEKB. Emittance growth resulted from both wakefield at the acceleration structure and dispersive effects at the focusing structure are troublesome in keeping the beam quality during the beam propagation. In this study, a possible solution to mitigate these effects in the KEK injector linac is explored by considering bunch compression in an existing bending section, orbit correction to suppress the wakefield excitation, and beam optics design.

TUPPC023	Waist Corrections at the Interaction Point of ATF2 in the Presence of IPBSM Fringe Rotations and Input Beam Sigma13, Sigma24	sextupole, coupling, quadrupole, alignment	1212
	S. Bai, J. Gao IHEP, Beijing, People's Republic of China P. Bambade LAL, Orsay, France
	The ATF2 project is the final focus system prototype for ILC and CLIC linear collider projects, with a purpose to reach a 37nm vertical beam size at the interaction point. In beam tuning towards the goal beam size, the presence of a tilt of the IP Shintake monitor fringe pattern with respect to the x-y coordinate system of the beam (or equivalently a σ13 correlation), as well as a σ24 correlation, can break the orthogonality in the main σ34 and σ32 waist corrections during the minimization and result in larger vertical beam sizes at IP. Both effects are studied, analytically and in simulation, and a practical procedure is suggested for diagnosing the presence of a residual fringe tilt, by measuring the influence of the horizontal waist correction on the minimum vertical beam size.

TUPPC024	R&D of an Ultrafast Probe Apparatus Based on MeV Electron Diffraction at Tsinghua University	electron, solenoid, 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.

TUPPC026	Design of Compact C-Band Standing-Wave Accelerating Structure Enhancing RF Phase Focusing	coupling, bunching, cavity, focusing	1221
	H.R. Yang, M.-H. Cho, J. Jang, S.H. Kim, W. Namkung, S.J. Park POSTECH, Pohang, Kyungbuk, Republic of Korea J.-S. Oh NFRI, Daejon, Republic of Korea
	Funding: Work supported by POSTECH Physics BK21 Program. We design a C-band standing-wave accelerating structure for an X-ray source of the imaging and medical applications. It is capable of producing 6-MeV, 100-mA pulsed electron beams which is focused by less than 1.5 mm without external magnets. As an RF source, we use peak 1.5-MW magnetron with duty factor of 0.08%. The accelerating structure is a bi-periodic and on-axis-coupled structure with a built-in bunching section, which consists 3 bunching cells, 13 normal cells and a coupler cell. It operated with π/2-mode standing-waves. The bunching section is designed to enhance the RF phase focusing in order to achieve 1.2-mm beam spot size. Each cavity is designed with the MWS code to maximize the effective shunt impedance within 3.5% inter-cell coupling. In this paper, we present design details of RF cavities and the beam dynamics simulation by the PARMELA code.

TUPPC035	Design of a Surface Muon Beam Line for High Field muSR at the PSI Proton Accelerator Facility	quadrupole, focusing, proton, secondary-beams	1236
	D. Reggiani, K. Deiters, P. Kaufmann, Y. Lee, T. Prokscha, T. Rauber, R. Scheuermann, K. Sedlak, V. Vranković Paul Scherrer Institut, Villigen, Switzerland
	Starting from 2012, a high field muSR (muon spin rotation/relaxation/resonance) facility will come into operation in the piE3 secondary beam line located at the target station E of the PSI proton accelerator. For this purpose, the last part of the beam line has been redesigned in order to integrate two electrostatic spin rotator devices providing a 90° rotation of the muon spin. At the same time, requirements of small beam diameter (σ ≈ 10 mm) as well as small momentum bite (δ_p/p ≈ 1%) in the sample region have to be met. This work focuses on the simulation of the beam optics (28 MeV/c design momentum). Particular concern is given to potential transmission losses caused by the spin rotator devices. The matching of the beam line with the high magnetic field up to 9.5 T surrounding the sample region has been considered as well. An overview of the spin rotator devices, specifically designed for this project, is also presented.

TUPPC045	Modeling Investigation on a Deflecting-Accelerating Composite RF-cavity System for Phase Space Beam Control	cavity, coupling, klystron, electron	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.

TUPPC048	Online Physics Model Platform	controls, EPICS, lattice, monitoring	1275
	P. Chu, Y. Zhang FRIB, East Lansing, Michigan, USA C. Benatti, V. Vuppala NSCL, East Lansing, Michigan, USA D. Dohan, G. Shen BNL, Upton, Long Island, New York, USA J. Wu SLAC, Menlo Park, California, USA
	Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661 For a complex accelerator such as the Facility for Rare Isotope Beams (FRIB), a transfer matrix based online model might not be sufficient for the entire machine. On the other hand, if introducing another modelling tools, physics applications have to be rewritten for all modelling tools. A platform which can host multiple modelling tools would be ideal for such scenario. Furthermore, the model platform along with infrastructure support can be used not only for online applications but also for offline purposes with multi-particle tracking simulation. In order to achieve such a platform, a set of common physics data structures has to be set. XAL's accelerator hierarchy based data structure is a good choice as the common structure for various models. Application Programming Interface (API) for physics applications should also be defined within a model data provider. A preliminary platform design and prototype is discussed.

TUPPC049	A Tapered-foil Emittance-exchange Experiment at LANSCE	emittance, proton, scattering, collimation	1278
	R.C. McCrady LANL, Los Alamos, New Mexico, USA
	We are planning an experiment at the Los Alamos Neutron Science Center (LANSCE) to demonstrate a technique for reducing the transverse emittance of the proton beam by passing the beam through a wedge-shaped energy degrader to produce a non-symplectic correlation between transverse position and energy, then removing this correlation with a bending magnet. This technique was proposed by Peterson* in 1983. We present a specific beamline layout that is expected to mitigate several complications associated with fielding an experiment to demonstrate the technique with a low-emittance proton beam. We present simulated results and expected outcomes of this demonstration. * J. M. Peterson, Proc. of PAC 1983, pP. 2403-2405 (1984).

TUPPC051	FACET Tolerances for Static and Dynamic Misalignment	quadrupole, plasma, sextupole, wakefield	1284
	J.T. Frederico, M.J. Hogan, T.O. Raubenheimer SLAC, Menlo Park, California, USA
	Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515. The Facility for Advanced Accelerator and Experimental Tests (FACET) at the SLAC National Accelerator Laboratory is designed to deliver a beam with a transverse spot size on the order of 10 μm x 10 μm in a new beamline constructed at the two kilometer point of the SLAC linac. Commissioning the beamline requires mitigating alignment errors and their effects, which can be significant and result in spot sizes orders of magnitude larger. Sextupole and quadrupole alignment errors in particular can introduce errors in focusing, steering, and dispersion which can result in spot size growth, beta mismatch, and waist movement. Alignment errors due to static misalignments, mechanical jitter, energy jitter, and other physical processes can be analyzed to determine the level of accuracy and precision that the beamline requires. It is important to recognize these effects and their tolerances in order to deliver a beam as designed.

TUPPC052	Longitudinal Beam Tuning at FACET	linac, diagnostics, wakefield, klystron	1287
	N. Lipkowitz, F.-J. Decker, J. Sheppard, S.P. Weathersby, U. Wienands, M. Woodley, G. Yocky SLAC, Menlo Park, California, USA
	Commissioning of the Facility for Advanced acCelerator Experimental Tests (FACET) at SLAC began in July 2011. In order to achieve the high charge density required for users such as the plasma wakefield acceleration experiment, the electron bunch must be compressed longitudinally from ~6 mm down to 20 microns. This compression scheme is carried out in three stages and requires careful tuning, as the final achievable bunch length is highly sensitive to errors in each consecutive stage. In this paper, we give an overview of the longitudinal dynamics at FACET, including beam measurements taken during commissioning, tuning techniques developed to minimize the bunch length, optimization of the new “W” chicane at the end of the linac, and comparison with particle tracking simulations. In addition, we present additional diagnostics and improved tuning techniques, and their expected effect on performance for the upcoming 2012 user run.

TUPPC058	Beam Energy Variation with Dipole Fault	dipole, sextupole, closed-orbit, lattice	1305
	Y. Li, S. Krinsky BNL, Upton, Long Island, New York, USA
	Funding: Supported by Department of Energy Contract No. DE-AC02-98CH10886. The effect of dipole faults and closed orbit correction on the beam energy is studied both analytically and numerically using the ELEGANT code. Motivated by top-off safety analysis, we consider the case of single dipole faults and study how large an error can be compensated by the closed orbit correction system before the beam is lost.

TUPPC060	Beam Optics and the pp2pp Setup of the STAR Experiment at RHIC	quadrupole, proton, optics, scattering	1311
	P.H. Pile, W. Guryn, J.H. Lee, S. Tepikian, K. Yip 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 newly installed forward detector system at the STAR experiment at RHIC measures small angle elastic and inelastic scattering of polarized protons on polarized protons. The detector system makes use of a pair of Roman Pot (RP) detectors, instrumented with silicon detectors, and located on either side of the STAR intersection region downstream of the DX and D0 dipoles and quadrupole triplets. The parallel to point optics is designed so that scattering angles are determined from position measurements at the RP's with small error. The RP setup allows measurement of position and angle for a subset of the scattered protons. These measured position/angle correlations at the RP's can be compared with optics model predictions to get a measure of the accuracy of the quadrupole triplet current settings. The current in each quadrupole in the triplets is comprised of sums and differences of up to six power supplies and an overall 1% error in the triplet field strengths results in a 4% error in four-momentum transfer squared. This technique is also useful to check the polarity of the skew elements located in each quadrupole triplet. Results of the analysis will be presented.

TUPPC070	Alternating Spin Aberration Electrostatic Lattice for EDM Ring	lattice, quadrupole, proton, storage-ring	1332
	Y. Senichev, R. Maier, D. Zyuzin FZJ, Jülich, Germany M. Berz MSU, East Lansing, Michigan, USA
	The idea of the electric dipole moment search using the storage ring (SrEDM) with polarized beam is realized under condition of the long-time spin coherency of all particles, the time during which the RMS spread of the spin orientation of all particles in the bunch reaches one radian. Following the requirements of the planned EDM experiment, the SCT should be more than 1000 seconds. During this time each particle performs about 10⁹ turns in the storage ring moving on different trajectories through the optics elements. At such conditions the spin-rotation aberrations associated with various types of space and time dependent nonlinearities start to play a crucial role. In this paper we consider a new method based on the alternating spin drift, causing it to rotate alternately, thereby limiting the growth of aberrations at one order of magnitude lower. As a result, using this method we can achieve the SCT of the order of 5000-6000 seconds. The difficulties of these studies are still in the fact that the aberrations growth observed in the scale of a 10⁹ turns. For the study we use an analytical method in composition with a numerical simulation by COSY Infinity.

TUPPC071	Comparison of Different Numerical Modelling Methods for Beam Dynamics in Electrostatic Rings	lattice, quadrupole, optics, proton	1335
	D. Zyuzin, R. Maier, Y. Senichev FZJ, Jülich, Germany S.N. Andrianov, A.N. Ivanov St. Petersburg State University, St. Petersburg, Russia M. Berz MSU, East Lansing, Michigan, USA
	To search the electric dipole moment was proposed to use polarized protons at the so-called "magic" momentum of 0.7 GeV/c in an electric storage ring. For studying beam dynamics in electrostatic rings different computational methods can be used. We used differential algebra methods realized in COSY Infinity and integrating program with symplectic Runge-Kutta methods. These methods were observed and compared for orbital and spin motion.

TUPPC077	Numerical Study of Beam Trapping in Stable Islands for Simple 2D Models of Betatronic Motion	emittance, resonance, extraction, octupole	1350
	M. Giovannozzi, C. Hernalsteens CERN, Geneva, Switzerland
	An essential ingredient for the proposed Multi-Turn Extraction (MTE) at the CERN PS is the beam trapping in stable islands. The control of the trapping process is essential for the quality of the final beam in terms of intensity sharing and emittance. In this paper, the splitting process is studied quantitatively by means of numerical simulations performed on 2D model representing the horizontal non-linear betatronic motion. The results are reviewed and discussed in details.

TUPPC079	Tracking LHC Models with Thick Lens Quadrupoles: Results and Comparisons with the Standard Thin Lens Tracking	quadrupole, lattice, optics, dipole	1356
	M. Giovannozzi, H. Burkhardt, T. Risselada CERN, Geneva, Switzerland
	So far, the massive numerical simulation studies of the LHC dynamic aperture were performed using thin lens models of the machine. This approach has the clear advantage of speed, but it has also the disadvantage of requiring re-matching of the optics from the real thick configuration to the thin one. Furthermore, as the figure-of-merit for the re-matching is the agreement between the beta-functions for the two model, while the quadrupole gradients are left free parameters, the effect of the magnetic multipoles might be affected by this approach and in turn the dynamic aperture computation. In this paper the new approach is described and the results for the dynamic aperture are compared with the old approach, including detailed considerations on the CPU-time requirements.

TUPPC080	Investigations of Scaling Laws of Dynamic Aperture with Time for Numerical Simulations including Weak-Strong Beam-Beam Effects	injection, dynamic-aperture, beam-beam-effects, lattice	1359
	M. Giovannozzi CERN, Geneva, Switzerland E. Laface ESS, Lund, Sweden
	A scaling law describing the time-dependence of the dynamic aperture, i.e., the region of phase space where stable motion occurs, was proposed in previous papers about ten years ago. It was shown that dynamic aperture has a logarithmic dependence on time, which would be suggested by some fundamental theorems of the theory of dynamical systems. So far, such a law was applied to single-particle effects only, i.e., the only source of non-linear effects was the magnetic imperfections. In this paper an attempt is made to extend the scaling law to the case of weak-strong beam-beam effects. The results of numerical simulations performed, including both non-linear magnetic imperfections and weak-strong beam-beam effects, are presented and discussed in detail.

TUPPC090	Beam Physics of Integrable Optics Test Accelerator at Fermilab	betatron, resonance, lattice, optics	1371
	A. Valishev, S. Nagaitsev Fermilab, Batavia, USA V.V. Danilov ORNL, Oak Ridge, Tennessee, 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. Fermilab's Integrable Optics Test Accelerator is an electron storage ring designed for testing advanced accelerator physics concepts, including implementation of nonlinear integrable beam optics and experiments on optical stochastic cooling. The machine is currently under construction at the Advanced Superconducting Test Accelerator facility. In this report we present the goals and the current status of the project, and describe the details of machine design. In particular, we concentrate on numerical simulations setting the requirements on the design and supporting the choice of machine parameters.

Paper

Title

Other Keywords

Page

MOYCP01

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

electron, focusing, betatron, optics

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]

MOOBB01

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

emittance, cavity, electron, 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]

MOEPPB007

Studies of eRHIC Coherent Instabilities

proton, impedance, betatron, space-charge

91

G. Wang, M. Blaskiewicz
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 the presence of an effective coherent electron cooling, the rms ion bunch length in eRHIC will be kept at 8.4cm, which is about a factor of 3 shorter than the current RHIC rms bunch length. Together with a factor of 2 increase in bunch intensity, coherent instabilities could be a potential limitation for achieving desired machine performance. In this study, we use the tracking code TRANFT to find thresholds and growth rates for various single bunch and coupled bunch instabilities with linear chromaticity and amplitude dependent tune shift taken into account. Based on the simulation results, requirements of machine parameters such as rf voltage, linear chromaticity, and octupole strength are specified to avoid these instabilities.

MOEPPB008

Simulation of Hollow Electron Beam Collimation in the Fermilab Tevatron Collider

electron, 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.

MOEPPB012

High-performance Beam Simulator for the LANSCE Linac

space-charge, linac, controls, EPICS

103

X. Pang, S.A. Baily, L. Rybarcyk
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 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 a 100-MeV drift tube linac and an 800-MeV coupled cavity linac. During beam operations, linac parameters are adjusted to maintain minimal beam spill, but without detailed knowledge of the beam distribution. A more desirable situation would be one where knowledge of the beam distribution along the linac is available to aid in the optimization of the linac operation and beam performance. We are presently developing a high performance simulator that will provide valuable information about the beam distribution in pseudo real-time during linac operations. The heart of the simulator is based upon the multiparticle beam dynamics code PARMILA, but implemented in C++ using NVIDIA’s CUDA technology for Graphics Processing unit (GPU) hardware. Linac operating set points will be provided by the EPICS control system so that changes are tracked and the simulation results updated automatically. Details regarding the approach, benefits and performance will be presented.

MOEPPB013

Simulation and Measurement of Beam Loss in the Narrow-Gap Undulator Straight Section of the Advanced Photon Source Storage Ring

undulator, vacuum, radiation, neutron

106

J.C. Dooling, 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 number DE-AC02-06CH11357.
Simulations indicate the removal of a scraper/collimator in the Sector 37 straight section (SS) of the Advanced Photon Source storage ring (SR) results in increased beam loss in the remaining narrow-gap, insertion device SS, ID4. Modeling with elegant provides loss distributions in the 5-mm aperture vacuum chamber of ID4 and includes the effects of rf system muting and quantum excitation in the bunch. The loss distributions are then used as input to a MARS model of the SS that includes undulator geometry. ID4 has been instrumented with additional monitoring to capture beam loss events, particularly beam dumps. Cerenkov detectors and fiber-optic cable bundles are used to capture temporal profiles of beam loss events. Beam dumps deliver 2600 J to the vacuum chamber and surrounding hardware including undulators. Data indicate a variety of temporal profiles occur during the beam dumps, with the shortest lasting 6 microseconds, FWHM (<2 turns). Such high power and power densities can lead to physical damage of vacuum components if not handled correctly. Touschek scattering loss is also a concern for undulator demagnetization. Comparison of modeling and measurements will be presented.

MOPPC001

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

electron, 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.

MOPPC003

Very Fast LHC Crab Cavity Failures and their Mitigation

luminosity, betatron, cavity, optics

121

T. Baer, R. Calaga, R. De Maria, S.D. Fartoukh, E. Jensen, R. Tomás, J. Tückmantel, J. Wenninger, B. Yee-Rendon, F. Zimmermann
CERN, Geneva, Switzerland
T. Baer
University of Hamburg, Hamburg, Germany

For the high-luminosity LHC upgrade program (HL-LHC), the installation of crab cavities (CCs) is needed to compensate the geometric luminosity loss due to the crossing angle and for luminosity leveling [*]. The baseline is a local scheme with CCs around the ATLAS and CMS experiments. In a failure case (e.g. a control failure or arcing in the coupler), the voltage and/or phase of a CC can change significantly with a very fast time constant of the order of 1 to 10 LHC turns. This can lead to large, global betatron oscillations of the beam. The impact of CC failures on the beam dynamics is discussed and the results from dedicated simulations are presented. Mitigation strategies to limit the impact of CC failures to an acceptable level are proposed.
* F. Zimmermann and O. Brüning, “Parameter Space for the LHC High-Luminosity Upgrade”, IPAC'12, MOPPC005, May 2012.

MOPPC018

Single/Few Bunch Space Charge Effects at 8 GeV in the Fermilab Main Injector

space-charge, background, factory, proton

163

D.J. Scott, D. Capista, I. Kourbanis, K. Seiya, M.-J. Yang
Fermilab, Batavia, USA

For Project X, it is planned to inject a beam of 3 10¹¹ particles per bunch into the Main Injector. Therefore, at 8 GeV, there will be increased space charge tune shifts and an increased incoherent tune spread. In preparation for these higher intensity bunches exploratory studies have commenced looking at the transmission of different intensity bunches at different tunes. An experiment is described with results for bunch intensities between 20 and 172 10⁹ particles. To achieve the highest intensity bunches coalescing at 8 GeV is required, resulting in a longer bunch length. Comparisons show that similar transmission curves are obtained when the intensity and bunch length have increased by factors of 3.2 and 3.4 respectively, indicating the incoherent tune shifts are similar, as expected from theory. The results of these experiments will be used in conjugation with simulations to further study high intensity bunches in the Main Injector.

MOPPC023

Polarization Transmission at RHIC, Numerical Simulations

polarization, resonance, optics, proton

178

F. Méot, M. Bai, C. Liu, M.G. Minty, V.H. Ranjbar
BNL, Upton, Long Island, New York, USA

Ray-tracing methods, using the computer code Zgoubi, have proven efficient for beam and spin dynamics simulations in RHIC (see earlier PAC and IPAC publications). More simulations and results are being produced, including spin code benchmarking and cross-checking, effects of strongest resonances and working point on transport of polarization, polarization with Run 9 and Run 11 measured ramp orbit and optics, polarization profiles, etc. The numerical methods involved are recalled, a status of the work is given.

MOPPC024

Modelling of the AGS Using Zgoubi - Status

optics, closed-orbit, multipole, coupling

181

F. Méot, L. A. Ahrens, Y. Dutheil, J.W. Glenn, H. Huang, T. Roser, V. Schoefer, N. Tsoupas
BNL, Upton, Long Island, New York, USA

A computer model, based on the ray-tracing code Zgoubi, is being developed in view of on-line simulation of the RHIC injector AGS, and of beam and spin dynamics simulations and studies in the presence of the cold and warm helical partial snakes. A status of this work is given here.

MOPPC026

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

electron, resonance, proton, 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.

MOPPC027

Synchro-Betatron Effects in the Presence of Large Piwinski Angle and Crab Cavities at the HL-LHC

betatron, luminosity, coupling, damping

190

S.M. White
BNL, Upton, Long Island, New York, USA
R. Calaga
CERN, Geneva, Switzerland
R. Miyamoto
ESS, Lund, Sweden

Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
The reduction of beta-star at the collision points for the high luminosity LHC (HL-LHC) requires an increment in the crossing angle to maintain the normalized beam separation to suppress the effects of long-range beam-beam interactions. However, increase in crossing angle may give rise to synchro-betatron resonances which may negatively affect the beam emittance and lifetime. 6D weak-strong and strong-strong simulations are performed to study the effect of synchro-betatron resonances in the context of the HL-LHC layout and its suppression via crab crossing.

MOPPC028

Coherent Beam-Beam Effects Observation and Mitigation at the RHIC Collider

emittance, damping, coupling, dipole

193

S.M. White, M. Bai, W. Fischer, Y. Luo, A. Marusic, M.G. Minty
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.
In polarized proton operation in RHIC coherent beam-beam modes are routinely observed with beam transfer function measurements in the vertical plane. With the existence of coherent modes a larger space is required in the tune diagram than without them and stable conditions can be compromised for operation with high intensity beams as foreseen for future luminosity upgrades. We report on experiments and simulations carried out to understand the existence of coherent modes in the vertical plane and their absence in the horizontal plane, and investigate possible mitigation strategies.

MOPPC029

Off-momentum Beat-beat Correction in the RHIC Proton Run

sextupole, quadrupole, proton, lattice

196

Y. Luo, M. Bai, W. Fischer, A. Marusic, K. Mernick, S.M. White
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 this article we will present the measurement and correction of the off-momentum β^*-beat in the RHIC proton run. The beta-beat will be measured with the AC dipole and by shifting RF frequency. We will focus on the correction of the off-momentum beta-beat at the interaction points IP6 and IP8 with the arc chromatic sextupole families. The effects of the off-momentum beta-beat correction on the global chromaticities and dynamic aperture will be estimated through beam experiments and the numerical simulation.

MOPPC034

Use of Helical Transport Channels for Bunch Recombination

collider, luminosity, emittance, focusing

205

D.V. Neuffer, K. Yonehara
Fermilab, Batavia, USA
C.M. Ankenbrandt, C. Y. Yoshikawa
Muons, Inc, Batavia, USA

Cooling scenarios for a high-luminosity Muon Collider require bunch recombination for optimal luminosity. In this paper we describe a new method for bunch recombination. We combine the high-chronicity of a helical transport channel (HTC) with the high-frequency bunching and phase-energy rotation concept (time-reversed) to obtain a compact bunch recombination system adapted to a muon collider scenario. We first present an idealized 1-D system with multiple chronicity transports. We then implement the concept in a single-chronicity channel, obtaining bunch recombination of 13 200MHz-spaced bunches to a single collider-ready bunch within a compact transport with modest rf requirements. That example is demonstrated within G4BL 3-D simulations. Variations and adaptations for different recombination requirements are discussed.

MOPPC037

Muon Collider Detector Backgrounds

collider, background, electron, 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, electron, hadron

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.

MOPPC042

Higgs Boson Muon Collider Factory: h⁰, A, H Studies

collider, factory, solenoid, dipole

226

D.B. Cline, X.P. Ding, J.L. Lederman
UCLA, Los Angeles, California, USA

With the recent hints of the Higgs boson from the LHC and a mass near 125 GeV/c we re-propose to study and build a muon collider Higgs factory to study the Higgs in the S channel. This was first proposed in 1992 by the first author. It is essential to study the Higgs boson for clues to new physics. The formation of the DOE MAP program, recent advances in 6D μ cooling methods, simulation, and targeting make this a feasible project to initiate at this time. This collider would fit into the FNAL site.

MOPPC046

End-to-End G4Beamline Simulation of an Inverse Cyclotron for Muon Cooling

cyclotron, emittance, solenoid, extraction

238

T.L. Hart, T.H. Luo, D.J. Summers
UMiss, University, Mississippi, USA
K. Paul
Tech-X, Boulder, Colorado, USA

An inverse cyclotron is a novel, intriguing idea for muon cooling necessary for proposed neutrino factories and muon colliders. We present the latest results of an end-to-end inverse cyclotron simulation that cools muons in the following sequence: single turn injection and initial cooling of 100 MeV kinetic energies to about 5 MeV with lithium hydrogen wedges; further substantial cooling to keV range kinetic energies and trapping with carbon foils and a rising electric field; and re-acceleration of the cooled, trapped muons back to 100 MeV. For neutrino factory and muon collider applications, the time of the entire cooling/trapping/re-acceleration process needs to be comparable to the muon lifetime so that decay losses are tolerable and the acceptance of the inverse cyclotron needs to be sufficiently large (on order 10 mm-rad normalized emittance). The latest progress toward these ends is presented.

MOPPC053

Modeling of Bending Magnets for SIRIUS

dipole, multipole, lattice, sextupole

250

X.R. Resende, R. Basílio, L. Liu, P.P. Sanchez, G. Tosin
LNLS, Campinas, Brazil

The new Brazilian synchrotron source, Sirius, will be a 3 GeV storage ring with a triple bend lattice with a minimum emittance of 1.7 nm rad. The ring dipoles are excited with permanent magnets. The middle bend has a small 1.4 degree slice in its center with 1.94 T field and serve as an additional hard X-ray source with critical energy of 11.6 keV. Other bending magnets have low 0.50 T field with gradients, allowing for a further emittance reduction. The bending slice shows a longitudinal profile with no uniform field plateau and with long-range fringe fields which are coupled with the fields of neighbouring dipoles. To take into account the interaction of the field-intersecting dipoles, realistic 3D models of the magnets have been created and their field configuration solved using finite element techniques. Field maps calculated from the 3D magnet models were used for the construction of segmented models of bend elements in beam dynamics codes.

MOPPC054

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

electron, gun, linac, 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.

MOPPC055

A New Platform for Global Optimization

linac, TRIUMF, solenoid, emittance

256

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

Funding: Funding is received from Natural Sciences and Engineering Research Council of Canada and National Research Council of Canada for this research.
This paper describes a new platform for the multi-objective global optimization of accelerator design. While local optimization is relatively simple, global optimization for accelerator design remains a challenging task. The user often must write many lines of code to combine the output of a large variety of simulation engines, then send the results to the optimization engine. The optimization code also requires significant revision when applied to different problems. This paper presents an alternative method. The TRIUMF optimization platform, based on the genetic algorithm, is an extension of the PISA framework. It uses a flexible XML input format, in which users can easily combine multiple physics engines, such as ASTRA and PARMELA, into the same optimization problem. The TRIUMF platform is also parallel capable, designed to take advantage of computation clusters such as WestGrid. Results of the optimization platform applied to TRIUMF's 50 MeV, 0.5 MW electron linac are shown.

MOPPC056

The SolMaxP Code

plasma, laser, target, beam-transport

259

A. Chancé, N. Chauvin, R.D. Duperrier
CEA/DSM/IRFU, France

In modern sciences, use of high performance computing (HPC) has become a necessity to move forward in the modeling of complex systems. For large-scale instruments like accelerators, HPC permits the virtual prototyping of very onerous parts and, thus, helps to reduce development costs. The SolMaxP code (for Solving Maxwell in Plasma) has been developed to allow complex simulations of multi-species plasma coupled with electromagnetic fields, whether the electromagnetic background is or is not self-consistent with the plasma dynamics. This paper presents the main algorithm of the code and gives several examples of applications.

MOPPC059

Various Approaches to Electromagnetic Field Simulations for RF Cavities

cavity, impedance, electromagnetic-fields, HOM

268

C. Liu, W. Ackermann, W.F.O. Müller, T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Work supported by BMBF under contract 05H09RD5.
The Superconducting Proton Linac (SPL) cavity is mainly designed and conducted by CERN. It is a part of the planned injector upgrade of the Large Hadron Collider (LHC). The SPL cavity is used to accelerate the ion beam from 160 MeV to 5GeV and served as a driver for neutrino facilities and radioactive beam facilities. In the Superconducting Proton Linac (SPL) cavity, it is very important to calculate the eigenmodes precisely, because many higher-order modes (HOMs) can lead to particle beam instabilities. We used and compared three different ways to calculate the eigenmodes in the SPL cavity: field simulation with hexahedron mesh in frequency domain, field simulation with hexahedron mesh in time domain, and field simulation with tetrahedral mesh and higher order curvilinear elements. In this paper the principles of the three numerical methods will be introduced and compared. Finally the calculated results will be presented.

MOPPC063

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

electron, 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, electron, 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, electron, cathode, 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

impedance, electron, 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.

MOPPC069

Quantitative Simulation of NIRS-930 Cyclotron

cyclotron, acceleration, extraction, electromagnetic-fields

292

V.L. Smirnov, S.B. Vorozhtsov
JINR/DLNP, Dubna, Moscow region, Russia
A. Goto, S. Hojo, T. Honma, K. Katagiri
NIRS, Chiba-shi, Japan

The results of the computer modelling of the structural elements of the NIRS-930 cyclotron operational at the National Institute of Radiological Sciences (Chiba, Japan) are presented. The integrated approach to modelling of the cyclotron, including calculation of electromagnetic fields of the structural elements and beam dynamics simulations is described. A computer model of the cyclotron was constructed. Electric and magnetic field distributions and mechanical structures were converted to the beam dynamics code for simulations, in which particle losses on the surfaces of the system elements were estimated. The existing data on the axial injection, magnetic, acceleration and extraction systems of the cyclotron and beam parameter measurements are used for calibration of the simulations. New acceleration regimes could be formulated with the help of the constructed computer model of the machine.

MOPPC070

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

cavity, electron, 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.

MOPPC073

Improvements in the PLACET Tracking Code

ground-motion, linac, alignment, multipole

301

A. Latina, E. Adli, D. Schulte, J. Snuverink
CERN, Geneva, Switzerland
B. Dalena
CEA/IRFU, Gif-sur-Yvette, France

The tracking code PLACET simulates beam transport and orbit corrections in linear accelerators. It incorporates single- and multi-bunch effects, static and dynamic imperfections. It has an interface based on both Tcl/Tk and Octave to provide maximum flexibility and easy programming of complex scenarios. Recently, new functionality has been added to expand its simulation and tuning capabilities, such as: tools to perform beam-based alignment of non-linear optical systems, possibility to track through the interaction region in presence of external magnetic fields (detector solenoid), higher order imperfections in magnets, better tools for integrated feedback loops. Moreover, self contained frameworks have been created to ease the simulation of CLIC Drive Beam, CLIC Main Beam, and other existing electron machines such as CTF3 and FACET.

MOPPC074

Evolution of MAD-X in the Framework of LHC Upgrade Studies

multipole, optics, luminosity, quadrupole

304

A. Latina, L. Deniau
CERN, Geneva, Switzerland

The design efforts for the High Luminosity upgrade of the Large Hadron Collider (HL-LHC) will require significant extensions of the MAD-X code widely used for designing and simulating particles accelerators. For this purpose, several new capabilities have been added to the code, namely the possibility to simulate crab cavities for crossing angle compensation, with their imperfections; the selective introduction of thick quadrupole elements for particles tracking, improving the previous implementation entirely based on thin-lenses; and the upgrade of the interface to SixTrack used for distributed tracking with, e.g., LHC@home. These changes are framed into a global redesign of the MAD-X architecture meant to consolidate its structure, improve its performances, and increase its flexibility. Such improvements are described in details in the present paper.

MOPPC075

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

electron, 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.

MOPPC078

Simulation Studies of Injection Scheme in TPS Storage Ring

injection, lattice, storage-ring, alignment

316

Y.C. Lee, H.-P. Chang, P.J. Chou
NSRRC, Hsinchu, Taiwan

Funding: NSRRC, Hsinchu, Taiwan.
The baseline lattice of TPS storage ring was finalized in October 2009. Later upon users’ request, we plan to implement the double mini-βy lattice in three 12-m straight sections of TPS storage ring. These locations were chosen to maintain the symmetry of the storage ring lattice. Particle tracking for the first few turns were used to check the injection scheme of storage ring, including errors introduced in manufacturing and installation process. Results of simulation studies will be presented.

MOPPC081

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

electron, cavity, 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.

MOPPC082

Beam Dynamics Simulations inProject X RFQ with CST Studio Suite

rfq, acceleration, linac, quadrupole

328

G.V. Romanov
Fermilab, Batavia, USA

Typically the RFQs are designed using the Parmteq, DesRFQ and other similar specialized codes, which produces the files containing the field and geometrical parameters for every cell. The beam dynamic simulations with these analytical fields are, of course, ideal realizations of the designed RFQs. The new advanced computing capabilities made it possible to simulate beam and even dark current in the realistic 3D electromagnetic fields in the RFQs that may reflect cavity tuning, presence of tuners and couplers, RFQ segmentation etc. The paper describes the utilization of full 3D field distribution obtained with CST Studio Suite for beam dynamic simulations using both PIC solver of CST Particle Studio and the beam dynamic code TRACK.

MOPPC083

LinguaFranca - A Graphical User Interface for Accelerator Modeling

quadrupole, lattice, optics, collider

331

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

This is a proposed project to develop an innovative Graphical User Interface that permits users to construct, explore, optimize, and evaluate accelerator systems efficiently and effectively. While it will be designed with students in mind, accelerator physicists will also find it useful in dealing with the plethora of modeling tools and their different languages. The internal representation of the system is specifically designed to be useable as a text-based description of the system, and to make it easy for users to interface it to essentially any accelerator-modeling tool, regardless of its description language. Many accelerator designers have expressed frustration with the current “Tower of Babel” among modeling programs, and this project will address that directly. In particular, this will make it straightforward to use fast but less realistic programs to design and optimize a system, and then use slower but more realistic programs to evaluate its performance. Graphical interfaces are emphasized, making it easy to construct the system graphically, display the system and its beam, and use on-screen controls to vary parameters and observe their effects immediately.

MOPPC085

An Integrated Green Function Poisson Solver for Rectangular Waveguides

synchrotron, space-charge, beam-beam-effects

337

R.D. Ryne
LBNL, Berkeley, California, USA

Funding: DOE Office of Science, Office of High Energy Physics and Office of Advanced Scientific Computing Research
A new method is presented for solving Poisson's equation inside a rectangular waveguide. The method uses Fast Fourier Transforms (FFTs) to perform mixed convolutions and correlations of the charge density with an integrated Green function. Due to its similarity to the widely used Hockney algorithm for solving Poisson's equation in free space, this capability can be easily implemented in many existing particle-in-cell beam dynamics codes.

MOPPC086

Accelerator Simulation - Beyond High Performance Computing

lattice, target, site, emittance

340

S. James, G.M. Jung, B.C. Li, K. Muriki, H. Nishimura, Y. Qin, K. Song, C. Sun
LBNL, Berkeley, California, USA

Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Accelerator modeling and simulation studies heavily rely on High Performance Computing (HPC). Public Cloud computing has opened a new service horizon for HPC by offering an on-demand, Virtual Private Cloud (VPC). Previously, we investigated using Amazon HPC public Cloud for lattice optimization applications and evaluated performance*. In this research, we use the Amazon VPC technology to extend local HPC resources to provide a seamless, hybrid, and secure environment when the demand for computing capacity spikes.
* C. Sun et al., "HPC Cloud Applied to Lattice Optimization," Proc. PAC2011, New York, WEP151, p. 1767 (2011).

MOPPC089

CUDA Kernel Design for GPU-based Beam Dynamics Simulations

acceleration, space-charge, impedance, linac

343

I.V. Pogorelov, K.M. Amyx, J. Balasalle, J. James
Tech-X, Boulder, Colorado, USA
M. Borland, R. Soliday, Y. Wang
ANL, Argonne, USA

Funding: Work supported by the US DOE Office of Science, Office of Basic Energy Sciences under grant number DE-SC0004585.
Efficient implementation of general-purpose particle tracking on GPUs can result in significant performance benefits to large-scale particle tracking and tracking-based accelerator optimization simulations. We present our work on CUDA kernels for transfer maps of single-particle-dynamics and collective-effects beamline elements, to be incorporated into a GPU-accelerated version of the ANL's accelerator code ELEGANT. In particular, we discuss techniques for efficient utilization of the device shared, cache, and local memory in the design of single-particle and collective-effects kernels. We also discuss the use of data-parallel and hardware-assisted approaches (segmented scan and atomic updates) for resolving memory contention issues at the charge deposition stage of algorithms for modeling collective effects. We present and discuss performance results for the CUDA kernels developed and optimized as part of this project.

MOPPC090

Coupling Modulator Simulations into an FEL Amplifier for Coherent Electron Cooling

FEL, electron, 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).

MOPPC091

Parallel 3D Simulations to Support Commissioning of a Solenoid-based LEBT Test Stand

rfq, solenoid, emittance, cyclotron

349

B.T. Schwartz, D.T. Abell, D.L. Bruhwiler, Y. Choi, S. Mahalingam, P. Stoltz, J. von Stecher
Tech-X, Boulder, Colorado, USA
B. Han, M.P. Stockli
ORNL, Oak Ridge, Tennessee, USA

Funding: This work is supported by the US DOE Office of Science, Office of Basic Energy Sciences, including grant No. DE-SC0000844.
A solenoid-based low-energy beam transport (LEBT) test stand is under development for the Spallation Neutron Source (SNS). To support commissioning of the test stand, the parallel Vorpal framework is being used for 3D electrostatic particle-in-cell (PIC) simulations of H⁻ beam dynamics in the LEBT, including impact ionization physics and MHz chopping of the partially-neutralized \Hm beam. Here we describe the process of creating a partially-neutralized beam and examine the effects of a single chopping event on the beam's emittance.

MOPPC093

Optimal Fast Multipole Method Data Structures

target, multipole, electron, 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.

MOPPC095

XAL's Online Model at ReA3 to Understand Beam Performance

linac, cavity, cryomodule, lattice

358

C. Benatti
NSCL, East Lansing, Michigan, USA
P. Chu, M.J. Syphers, X. Wu
FRIB, East Lansing, Michigan, USA

Funding: This material is based on work supported by the National Science Foundation under Grant No. PHY-1102511 and by Michigan State University.
The ReA3 facility at the NSCL at MSU has been designed to reaccelerate rare isotope beams to 3MeV/u. ReA3 consists of a charge to mass selection section, a normal conducting RFQ, a superconducting linac, and transport beam lines that deliver the beam to the experiments. The beam optics designs were developed using COSY and IMPACT. A code with an online model capable of interacting with the control system, such as XAL, developed at SNS, would be ideal for studying this system*. New elements have been added to XAL’s already extensive list of supported devices in order to model elements unique to the NSCL. The benchmarking process has been completed for establishing the use of XAL’s Online Model at the NSCL, and preliminary results from its use at the ReA3 control room have been obtained. The development of applications to fit the needs of the program is ongoing. A summary of the benchmarking process is presented including both transverse and longitudinal studies.
* J. Galambos et al., Proc. PAC 2005, p. 79, (2005); doi: 10.1109/PAC.2005.1590365.

MOPPC096

Multiphysics Applications of ACE3P

HOM, vacuum, cavity, SRF

361

K.H. Lee, C. Ko, Z. Li, C.-K. Ng, L. Xiao
SLAC, Menlo Park, California, USA
G. Cheng, H. Wang
JLAB, Newport News, Virginia, USA

Funding: Work supported by US DOE Offices of HEP, ASCR and BES under contract AC02-76SF00515.
The TEM3P module of ACE3P, a parallel finite-element electromagnetic code suite from SLAC, focuses on the multiphysics simulation capabilities, including thermal and mechanical analysis for accelerator applications. In this pa- per, thermal analysis of coupler feedthroughs to supercon- ducting rf (SRF) cavities will be presented. For the realistic simulation, internal boundary condition is implemented to capture RF heating effects on the surface shared by a di- electric and a conductor. The multiphysics simulation with TEM3P matched the measurement within 0.4%.

MOPPD003

DITANET - An International Network in Beam Diagnostics

diagnostics, emittance, instrumentation, monitoring

370

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

Funding: Work supported by the European Union under contract PITN-GA-2008-215080.
DITANET is the largest-ever EU funded research and training network in beam diagnostics. It brings together universities, research centers and industry partners to jointly develop diagnostics methods for a wide range of existing or future particle accelerators. This is achieved through a cohesive approach that allows for the exploitation of synergies, whilst promoting knowledge exchange between partners. In addition to its broad research program, the network organizes a large number of international schools and topical workshops for the beam instrumentation and particle accelerator communities. The project comes to an end in May 2012. This contribution presents some of the network's recent research outcomes and training activities.

MOPPD004

oPAC - Optimizing Accelerators through International Collaboration

laser, controls, instrumentation, emittance

373

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

Funding: Work supported by the European Union under contract PITN-GA-2011-289485.
The optimization of the performance of any particle accelerator critically depends on an in-depth understanding of the beam dynamics in the machine and the availability of simulation tools to study and continuously improve all accelerator components. It also requires a complete set of beam diagnostics methods to monitor all important machine and beam parameters with high precision and a powerful control and data acquisition system. Within the oPAC project all these aspects will be closely linked with the aim to optimize the performance of present and future accelerators that lie at the heart of many research infrastructures. The project brings together 22 institutions from around the world. With a project budget of 6 M€, it is one of the largest research and training networks ever funded by the EC. This contribution gives an overview of the network's broad research program and summarizes the training events that will be organized by the consortium within the next 4 years.

MOPPD005

Stochastic Cooling of Antiprotons in the Collector Ring at FAIR

pick-up, antiproton, kicker, ion

376

C. Dimopoulou, A. Dolinskii, F. Nolden, C. Peschke, M. Steck
GSI, Darmstadt, Germany

In order to reach the required luminosities for the experiments at FAIR, the hot secondary beams (antiprotons or rare isotopes) emerging from the production targets will be efficiently collected and phase-space cooled in the large-acceptance Collector Ring (CR), which is equipped with pertinent stochastic cooling systems. Simulations of the system performance are underway in parallel with the finalization of the system design. After an overview of the CR stochastic cooling systems, simulation results for antiproton cooling in the bandwidth 1-2 GHz are presented. The CERN Fokker-Planck code is used for momentum cooling and an analytical model based on "rms" theory for the simultaneous betatron cooling. In the focus is the comparison between the time of flight and the notch filter momentum cooling methods. The results are essential for system optimization as well as input for the users of the CR-precooled beams i.e. the HESR.

MOPPD012

Challenge for More Efficient Transverse Laser Cooling for Beam Crystallization

laser, synchrotron, ion, betatron

394

A. Noda, M. Nakao, H. Souda, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
M. Grieser
MPI-K, Heidelberg, Germany
Z.Q. He
TUB, Beijing, People's Republic of China
K. Ito, H. Okamoto, K. Osaki
HU/AdSM, Higashi-Hiroshima, Japan
K. Jimbo
Kyoto University, Institute for Advanced Energy, Kyoto, Japan
Y. Yuri
JAEA/TARRI, Gunma-ken, Japan

Funding: Work supported by Advanced Compact Accelerator Development project by MEXT. Also supported by GCOE project at Kyoto University, The next generation of Physics-Spun from Universality and Emergency.
At S-LSR in ICR, Kyoto University, Mg ion beam has been successfully laser cooled both in longitudinal* and transverse** directions. The cooling rate, however, is not strong enough to realize the crystalline beam due to the heating because of intra-beam scattering (IBS) effect. So as to suppress this IBS, reduction of the beam intensity is inevitable, which however, had resulted in poor S/N ratio for observation of the transverse beam size. In the present paper, we would like to describe a new beam scraping scheme, which selects out the beams in the distribution tail of the transverse phase space keeping the beam density in the core part by simultaneous application of multi-dimensional laser cooling and beam scraping. The strategy to reduce the beam intensity and hence beam heating due to IBS by a controlled scraping of the outskirt beam keeping the beam density at core part almost the same, has been searched by combination of the beam experiments and computer simulations.
* M. Tanabe et al., Applied Physics Express 1, 028001 (2008).
** M. Nakao et al., submitted to PRST-AB.

MOPPD021

An Experimental Investigation of Slow Integer Tune Crossing in the EMMA Non-scaling FFAG

acceleration, resonance, closed-orbit, proton

412

J.M. Garland, H.L. Owen
UMAN, Manchester, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Funding: Student STFC grant number: ST/G004277/1.
Results are presented from a slow integer tune crossing experiment performed in the EMMA accelerator. Under nominal conditions EMMA accelerates an electron beam from 10–20 MeV rapidly in 5–10 turns in a novel “serpentine” channel causing several transverse integer tunes to be crossed. During this rapid acceleration it has been shown that the betatron amplitude of the beam does not grow. If the potential of non-scaling FFAGs were to be realized in such fields as high-current proton acceleration then tune space would be crossed slower with acceleration in an RF bucket. The crossing speed in a non-scaling FFAG is in a previously unstudied intermediate region and hence conventional crossing theory may not apply. It was proposed to observe the effects on betatron amplitude when a beam crosses integer tunes by the variation of tune with momentum over a range of crossing speeds derived from different acceleration rates. This method can be realized by synchrotron acceleration inside a stable RF bucket. Betatron amplitude growth and beam loss as a function of turn are explored when crossing an integer tune and a relationship between crossing speed and these quantities is established.

MOPPD023

Correction of the nu_r=3/2 Resonance in TRIUMF Cyclotron

resonance, cyclotron, TRIUMF, extraction

415

T. Planche, R.A. Baartman, Y.-N. Rao
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

Imperfections in the TRIUMF cyclotron are a source of field errors which slightly violate the 6-fold symmetry of the ring. Among them, the third harmonic of the magnetic gradient errors drives the ν_r=3/2 resonance. This results in a modulation of the current density versus radius observed after the resonance crossing all the way to the extraction (480 MeV). The cyclotron has sets of harmonic correction coils at different radii, each set constituted of 6 pairs of coils placed in a 6-fold symmetrical manner. The 6-fold symmetry of this layout makes that a single set of harmonic coils cannot provide a full correction of third harmonic errors driving the ν_r=3/2 resonance. The last two sets of harmonic correction coils (number 12 and 13) are azimuthally displaced. In this study, we use this fact to achieve a full correction of the resonance. We also present experimental measurements that demonstrate the full correction.

MOPPD024

C70 Arronax in the Hands-On Phase

target, cyclotron, proton, injection

418

F. Poirier, S. Auduc, L. Lamouric
SUBATECH, Nantes, France
S. Girault, F. Gomez, E. Mace
Cyclotron ARRONAX, Saint-Herblain, France
C. Huet
EMN, Nantes, France

The C70 Arronax, is a high-intensity (2x375 μA) and high-energy (70 MeV) multiparticle cyclotron that started its hands-on phase in December 2010. The operating and maintenance group is accumulating experience on this machine. A review of the machine status and present possibilities in terms of beam capacities is thus presented in this paper. The status of the beamline simulations is also given.

MOPPD027

A Compact High Intensity Cyclotron Injector for DAEδALUS Experiment

extraction, cyclotron, resonance, beam-losses

424

L. Calabretta, D. Rifuggiato
INFN/LNS, Catania, Italy
A. Adelmann
Paul Scherrer Institut, Villigen, Switzerland
A. Calanna, D. Campo
CSFNSM, Catania, Italy
M.M. Maggiore, L.A.C. Piazza
INFN/LNL, Legnaro (PD), Italy
J.J. Yang
CIAE, Beijing, People's Republic of China

Funding: Istituto Nazionale di Fisica Nucleare - Laboratori Nazionale del Sud.
The experiment DAEδALUS*, recently proposed by MIT scientist to search for CP violation in the neutrino sector, needs three accelerator with energy of about 800 MeV, average power of some MW and duty cycle of 20%. To reduce the cost of the accelerators a cyclotron complex consisting of an injector and of a booster ring cyclotron has been proposed**. The main characteristics of the new kind of separated sector cyclotron injector able to accelerate a H²⁺ molecule beam up to 60 MeV/n will be presented. Due to the low duty cycle, the peak current to be accelerated is 5 mA. The problem related to the injection of a H²⁺ beam, delivered by a compact ion source, and to the space charge effects will be discussed. To allow an easier injection in the booster Superconducting Ring Cyclotron the extraction energy has been increased up to 60 MeV/n. The pole gap was decreased to 60 mm to achieve a more efficient beam extraction. The updated configuration of the magnetic sectors, of the isochronous magnetic field and beam dynamics along extraction path and during the acceleration will be presented, too.
* J. Alonso et al., "Novel Search for CP Violation in the Neutrino Sector: DAEδALUS," Jun2010 e-Print: arXiv:1006.0260
** L. Calabretta, Proc. of IPAC 2011, WEPS073, p. 2673 (2011).

MOPPD028

Observation of Longitudinal Space Charge Effects in the Injection Beam Line of NIRS-930 Cyclotron

bunching, cyclotron, space-charge, injection

427

S. Hojo, A. Goto, T. Honma, K. Katagiri, A. Sugiura
NIRS, Chiba-shi, Japan

Dependence of bunching efficiencies on the position of a beam buncher was measured for the AVF cyclotron at the National Institute of Radiological Sciences (NIRS) for 30 MeV proton beams with intensities up to 100 microamperes at injection. The measurement was carried out for two positions: 1.53 m and 2.33 m upstream from the inflector. For the buncher position of 2.33 m the bunching efficiency decreased, as the beam intensity increased, to about half of that at low intensities, while for 1.5 m it was constant up to 100 microamperes. The intensity distributions of extracted beam with respect to the buncher phase were also measured for the two buncher positions. The dependence of bunch width on the beam intensity is discussed by comparing the data with one-dimensional simulations on longitudinal space charge effects.

MOPPD044

Optimization of the Target Subsystem for the New g-2 Experiment

target, proton, focusing, factory

460

C. Y. Yoshikawa, C.M. Ankenbrandt
Muons, Inc, Batavia, USA
A.F. Leveling, N.V. Mokhov, J.P. Morgan, D.V. Neuffer, S.I. Striganov
Fermilab, Batavia, USA

A precision measurement of the muon anomalous magnetic moment, aμ = (g-2)/2, was previously performed at BNL with a result of 2.2 - 2.7 standard deviations above the Standard Model (SM) theoretical calculations. The same experimental apparatus is being planned to run in the new Muon Campus at Fermilab, where the muon beam is expected to have less pion contamination and the extended dataset may provide a possible 7.5σ deviation from the SM, creating a sensitive and complementary benchmark for proposed SM extensions. We report here on a preliminary study of the target subsystem where the apparatus is optimized for pions that have favorable phase space to create polarized daughter muons around the magic momentum of 3.094 GeV/c, which is needed by the downstream g 2 muon ring.

MOPPD054

Effect of the 2011 Great East Japan Earthquake in the Injection and Extraction of the J-PARC 3-GeV RCS

injection, extraction, septum, beam-transport

490

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

In the 3-GeV rapid cycling synchrotron (RCS) of the Japan Proton Accelerator Research Complex (J-PARC), the injection and extraction systems play important roles for the beam injection and extraction, respectively. Unfortunately, the 2011 great east Japan earthquake had a serious impact on the ongoing schedule due to the big damage of the whole accelerator facility and the infrastructure as well. The injection and extraction including the beam transport lines magnets suffered a noticeable displacement resulting with alignment errors. As realignment of the RCS magnets can not be done in this year, then based on the post earthquake measured alignment data, we have estimated the effect as well as possible solutions on the injected and extracted beam for as usual operation. Fortunately, the simulation results shows that there would not be any serious impact on both injected as well as extracted beam with present alignment errors and thus user operation can be resume as expected. The simulation result together with some experimental results will be presented.

MOPPD061

LHC@home: a Volunteer Computing System for Massive Numerical Simulations of Beam Dynamics and High Energy Physics Events

HOM, collider, controls, superconducting-magnet

505

M. Giovannozzi, F. Grey, A. Harutyunyan, N. Hoimyr, P.L. Jones, A. Karneyeu, M.A. Marquina, E. McIntosh, B. Segal, P. Skands
CERN, Geneva, Switzerland
D. Lombraña González
CCC, 1211Geneva 23, Switzerland
L. Rivkin, I. Zacharov
EPFL, Lausanne, Switzerland

Recently, the LHC@home system has been revived at CERN. It is a volunteer computing system based on BOINC which allows boosting the available CPU-power in institutional computer centers by the help of individuals that donate the CPU-time of their PCs. Currently two projects are hosted on the system, namely SixTrack and Test4Theory. The first is aimed at performing beam dynamics simulations, while the latter deals with the simulation of high-energy events. In this paper the details of the global system, as well a discussion of the capabilities of either project will be presented. Milestones of progress of the projects will also be discussed.

MOPPD063

A 180 MeV Injection System for the ISIS Synchrotron

injection, dipole, synchrotron, electron

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.

MOPPD064

Simulation of Double Layer Carbon Stripping Foils for ISIS Injection Upgrades

injection, radiation, scattering, proton

514

H. V. Smith, D.J. Adams, B. Jones, C.M. Warsop
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
Y. Irie, Y. Takeda
KEK, Ibaraki, Japan

ISIS, the pulsed neutron and muon spallation source located at the Rutherford Appleton Laboratory (UK), currently delivers a mean beam power of 0.2 MW to target. A 70 MeV H linear accelerator feeds into a 50 Hz, 800 MeV proton synchrotron, accelerating up to 3·10¹³ protons per pulse. Potential injection scheme upgrades, aiming to raise average beam power towards 0.5 MW with a new 180 MeV linear accelerator, continue to be studied. This paper highlights recent results from temperature studies of double layer carbon foils, suitable for injection at 180 MeV into ISIS, using ANSYS. Experimental data from KEK was used to benchmark models and the variation of temperature as a function of foil separation was considered.

MOPPD073

Development of Transportation System for Low Energy Electron Group

electron, solenoid, collimation, 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.

MOPPD074

Localization of Large Angle Foil Scattering Beam Loss Caused by Multi-Turn Charge-Exchange Injection

collimation, injection, scattering, insertion

535

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

In the J-PARC RCS, the significant losses were observed at the branch of H⁰ dump line and the Beam Position Monitor which was put at the downstream of the H⁰ dump branch duct. These losses were caused by the large angle scattering of the injection and circulating beam at the charge exchange foil. To realize high power operation, we have to mitigate these losses. So, we started to develop a new collimation system in the H⁰ branch duct and installed in October 2011. In order to optimize this system efficiently, we primarily focused on the relative angle of collimator block from scattering particles. We simulated behavior of particles scattered by foil and produced by collimator block and researched most optimized position and angle of the collimator block. In this process, we devised the method of angular regulation of collimator block. We present the method of angular regulation and performance of this new collimation system.

MOPPD076

Numerical Study of a Collimation System to Mitigate Beam Losses in the ESS Linac

linac, DTL, beam-losses, collimation

541

R. Miyamoto, H. Danared, M. Eshraqi, A. Ponton
ESS, Lund, Sweden

The European Spallation Source (ESS) will be a 5 MW proton linac to produce spallation neutrons. A high power linac has a very low tolerance on beam losses, typically on the order of 1 W/m, to avoid activation of the linac components; hence, emittance and halo of the beam must be well controlled throughout the linac. A system of collimators in beam transport sections has been studied and tested as a means to mitigate the beam losses in several linacs. This paper presents the result of a numerical study of a collimation system for the ESS linac.

MOPPD078

Accelerator Physics Study on the Effects from an Asynchronous Beam Dump in the LHC Experimental Region Collimators

proton, kicker, betatron, optics

547

L. Lari, R.W. Assmann, V. Boccone, R. Bruce, F. Cerutti, A. Mereghetti, A. Rossi, V. Vlachoudis
CERN, Geneva, Switzerland
A. Faus-Golfe, L. Lari
IFIC, Valencia, Spain

Funding: This work has been carried out through of the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program.
Asynchronous beam aborts at the LHC are to be expected once per year. Accelerator physics studies of asynchronous dumps have been performed at different beam energies and beta-stars. The loss patterns are analyzed in order to identify the losses in particular on the Phase 1 Tertiary Collimators (TCT), since their Tungsten jaw insert has a low damage threshold with respect to the loss load expected. Settings for the tilt angle of the TCTs are discussed with the aim of reducing the thermal loads on the TCT themselves.

MOPPD079

Preliminary Thermo-Mechanical Analysis of Angular Beam Impact on LHC Collimators

collimation, kicker, superconducting-magnet, controls

550

M. Cauchi, R.W. Assmann, A. Bertarelli, F. Carra, A. Dallocchio, D. Deboy, N. Mariani, A. Rossi
CERN, Geneva, Switzerland
L. Lari
IFIC, Valencia, Spain
P. Mollicone
UoM, Msida, Malta
N.J. Sammut
University of Malta, Faculty of Engineering, Msida, Malta

Funding: This work is supported by EuCARD.
The correct functioning of the LHC collimation system is crucial to attain the desired LHC luminosity performance. However, the requirements to handle high intensity beams can be demanding. In this respect, accident scenarios must be well studied in order to assess if the collimator design is robust against likely error scenarios. One of the catastrophic - though not very probable - accident scenarios identified is an asynchronous beam dump coupled with slight angular misalignment errors of the collimator jaw. Previous work presented a preliminary thermal evaluation of the extent of beam-induced damage for such scenarios, where it was shown that in some cases, a tilt of the jaw could actually serve to mitigate the effect of an asynchronous dump on the collimators. This paper will further analyze the response of tertiary collimators in presence of such angular jaw alignments, with the aim to identify optimal operational conditions.

MOPPD081

Upgrade of the LHC Beam Dumping Protection Elements

extraction, kicker, dumping, vacuum

556

W.J.M. Weterings, T. Antonakakis, B. Balhan, J. Borburgh, B. Goddard, C. Maglioni, R. Versaci
CERN, Geneva, Switzerland

The Beam Dumping System for the Large Hadron Collider comprises for each ring a set of horizontally deflecting extraction kicker magnets, vertically deflecting steel septa, dilution kickers and finally, a couple of hundred meters further downstream, an absorber block. A mobile diluter (TCDQ) protects the superconducting quadrupole immediately downstream of the extraction as well as the arc at injection energy and the triplet aperture at top energy from bunches with small impact parameters, in case of a beam dump that is not synchronized with the particle free gap or a spontaneous firing of the extraction kickers. Simulations have shown that an asynchronous dump of a 7 TeV nominal beam into the TCDQ absorber blocks could damage it. This paper describes the proposed changes to this device in order to maintain the protection for the downstream elements while reducing the risk of damaging the TCDQ in case of such a beam loss.

MOPPP004

Further Study on Fast Cooling in Compton Storage Rings

laser, electron, storage-ring, 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, electron, 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.

MOPPP009

X-Ray Spectra Reconstruction of Thomson Scattering Source From Analysis of Attenuation Data

scattering, photon, target, laser

586

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

Thomson scattering X-ray source, in which the TW laser pulse is scattered by the relativistic electron beam, can provide ultra short, monochromatic, high flux, tunable polarized hard X-ray pulse which is can widely used in physical, chemical and biological process research, ultra-fast phase contrast imaging, and so on. Since the pulse duration of X-ray is as short as picosecond and the flux in one pulse is high, it is difficult to measure the x-ray spectrum. In this paper, we present the X-ray spectrum measurement experiment on Tsinghua Thomson scattering. The preliminary experimental results shows the maximum X-ray energy is about 47 keV, which is agree well with the simulations.

MOPPP010

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

lattice, radiation, electron, 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

electron, laser, 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, electron, dipole, 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).

MOPPP021

Longitudinal Beam Dynamics at the ALICE Acclerator R&D Facility

booster, linac, gun, FEL

610

F. Jackson, D. Angal-Kalinin, S.P. Jamison, J.W. McKenzie, T.T. Ng, Y.M. Saveliev, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The ALICE facility is an energy recovery test accelerator whose applications include an IR-FEL and THz generation. Of primary importance to the performance of the main ALICE applications is the understanding and control of the longitudinal dynamics, which are less amenable to measurement than the transverse. The longitudinal dynamics of the beam evolve are studied in simulation and experiment in several areas of the machine. Simulations of the low energy injector where space charge and velocity bunching may occur are presented. Path length measurement using time-of-arrival monitors are carried out.

MOPPP034

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

cavity, electron, dipole, emittance

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.

MOPPP036

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

cathode, electron, gun, dipole

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

MOPPP050

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

linac, emittance, gun, electron

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.

MOPPP053

Failure Mode Analysis in Preparation for Top-up Injection at the Canadian Light Source (CLS)

injection, storage-ring, dipole, kicker

682

L.O. Dallin
CLS, Saskatoon, Saskatchewan, Canada

Top-up injection involves injecting beam with beamline safety shutters open. Consequently it is extremely important that no electrons enter the beamlines where they could be a potential safety hazard to beamline personnel. To investigate the likelihood that electrons could exit the storage ring various failure mode simulations have been done. The approach is to account for all possible injection trajectories and show that these particles will be intercepted by various storage ring apertures before they reach an amplitude that is deemed unsafe. This amplitude was chosen to be 50 mm and the field roll-off of all storage ring magnets were defined to this amplitude. Failure modes invested included injection kicker failures, uncorrected misalignment errors, off-energy injection and shorted storage ring magnet coils. Errors that would render it impossible to store beam were not investigated. As some particles reached amplitudes beyond the safe limit measures have been devised to eliminate these unsafe scenarios.

MOPPP065

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

undulator, photon, status, electron

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

electron, undulator, vacuum, storage-ring

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.

MOPPP086

Praseodymium Iron-Boron Undulator With Textured Dysprosium Poles for Compact X-Ray FEL Applications

undulator, cryogenics, insertion, insertion-device

756

R.B. Agustsson, Y.C. Chen, T.J. Grandsaert, A.Y. Murokh
RadiaBeam, Santa Monica, USA
F.H. O'Shea
UCLA, Los Angeles, California, USA
V. Solovyov
BNL, Upton, Long Island, New York, USA

Funding: DOE SBIR #97134S11-I
Radiabeam Technologies is developing a novel ultra-high field short period undulator using two unconventional materials: praseodymium permanent magnets (PrFeB) and textured dysprosium (Tx Dy) ferromagnetic field concentrators. Both materials exhibit extraordinary magnetic properties at cryogenic temperatures, such as very large energy product and record high induction saturation, respectively. The proposed device combines PrFeB and Tx Dy in 3-D hybrid undulator geometry with sub-cm period and up to 3 Tesla pole tip field. Practical realization of these features will significantly surpass state-of-the-art and offer an ideal solution for the next generation of compact X-ray light sources. Initial simulations along with preliminary cryogenic measurements will be presented.

MOPPR007

Investigation of Techniques for Precise Compton Polarimetry at ELSA

electron, polarization, photon, laser

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.

MOPPR034

A Laser Wire System at Electron Beam Transport Line in BEPCII

laser, electron, photon, positron

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, electron, factory

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.

MOPPR042

Characterization Tests of a Stripline Beam Position Monitor for the CLIC Drive Beam

impedance, quadrupole, extraction, feedback

873

A. Benot-Morell, A. Faus-Golfe, J.J. García-Garrigós
IFIC, Valencia, Spain
A. Benot-Morell, L. Søby
CERN, Geneva, Switzerland
J.M. Nappa, J. Tassan-Viol, S. Vilalte
IN2P3-LAPP, Annecy-le-Vieux, France
S.R. Smith
SLAC, Menlo Park, California, USA

Funding: FPA2010-21456-C02-01, SEIC-2010-00028
A prototype of a stripline Beam Position Monitor (BPM) with its associated readout electronics has been developed at CERN in collaboration with SLAC, LAPP and IFIC. In this paper, the design and simulations of the BPM with the analog readout chain and the BPM test bench are described, and the results of the first characterization tests are presented. The position resolution and accuracy parameters are expected to be below 2μm and 20μm respectively for a beam with a bunching frequency of 12GHz, an average current of 101A and a machine repetition rate of 50Hz.

MOPPR046

CLIC Luminosity Monitoring

photon, luminosity, monitoring, background

885

A. Apyan, L.C. Deacon, E. Gschwendtner, T. Lefèvre
CERN, Geneva, Switzerland
R. Appleby, S.C. Tygier
UMAN, Manchester, United Kingdom

The CLIC post-collision line is designed to transport the un-collided beams and the products of the collided beams with a total power of 14MW to the main beam dump. Luminosity monitoring for CLIC is based on high energy muons produced by bremsstrahlung photons in the main dump. Threshold Cherenkov counters are proposed for the detection of these muons. The expected rates and layout for these detectors is presented. Another method for luminosity monitoring is to directly detecting the bremsstrahlung photons in the post-collision line; Full Monte Carlo simulation has been performed to address its feasibility.

MOPPR060

Calibration of the EMMA Beam Position Monitors: Position, Charge and Accuracy

pick-up, injection, quadrupole, diagnostics

921

I.W. Kirkman
The University of Liverpool, Liverpool, United Kingdom
J.S. Berg
BNL, Upton, Long Island, New York, USA
G. Cox
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
A. Kalinin
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

The accurate determination of transverse beam position is essential to understanding the performance of an accelerator system, and this is particularly the case with non-scaling FFAG machines such as EMMA, where, due to fundamental principles of design, the beam may deviate widely from the central beampipe axis. This paper describes the various modelling approaches taken for the three different button pickup assemblies used in EMMA, and the subsequent methods of calibration (‘mappings’) which allow beam position and charge to be deduced from the processed BPM signals. The use and validity of the modelling and mapping approach adopted is described, and the contributions to positional and bunch charge uncertainty arising from these procedures is discussed.

MOPPR063

Exploiting the Undesired: Beam-gas Interactions in the LHC

vacuum, radiation, proton, quadrupole

927

R. Versaci, V. Baglin, M. Brugger
CERN, Geneva, Switzerland
A. Mereghetti
UMAN, Manchester, United Kingdom

The vacuum inside the LHC pipes has a key role in correct operation of the accelerator. The interaction of the beam with residual gas in the pipes can lead to the loss of the beam itself and damage accelerator components. Nevertheless, beam-gas interactions can be exploited to indirectly measure the gas pressure inside the beam pipe, detecting the secondaries produced. The showers generated are detected by Beam Loss Monitors, whose signals depend on the gas pressure. This technique would also allow to punctually measure the gas pressure in sections of the accelerator where vacuum gauges are not frequent, such as the arcs. The problem has been addressed by means of FLUKA simulations and the results have been benchmarked with direct measurements performed in the LHC in 2011.

MOPPR066

Study of Transverse Pulse-to-Pulse Orbit Jitter at the KEK Accelerator Test Facility 2 (ATF2)

extraction, feedback, controls, linear-collider

936

J. Resta-López, J. Alabau-Gonzalvo
IFIC, Valencia, Spain
R. Apsimon, B. Constance, A. Gerbershagen
CERN, Geneva, Switzerland
D.R. Bett, P. Burrows, G.B. Christian, M.R. Davis, C. Perry
JAI, Oxford, United Kingdom

Funding: FPA2010-21456-C02-01
For future linear colliders the precise control and mitigation of pulse-to-pulse orbit jitter will be very important to achieve the required luminosity. Diagnostic techniques for the orbit jitter measurement and correction for multi-bunch operation are being addressed at the KEK Accelerator Test Facility 2 (ATF2). In this paper we present recent studies on the vertical jitter propagation through the ATF2 extraction line and final focus system. For these studies the vertical pulse-to-pulse position and angle jitter have been measured using the available stripline beam position monitors in the beamline. The cases with and without intra-train orbit feedback correction in the ATF2 extraction line are compared.

MOPPR067

Simulations of Fast X-ray Detectors Based on Multichannel Plates

electron, photon, 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.

MOPPR069

Use of Waveguide and Beam Pipe Probes as Beam Position and Tilt Monitoring Diagnostics with Superconducting Deflecting Cavities

cavity, dipole, HOM, monitoring

945

X. Sun, T.G. Berenc, G. Decker, G.J. Waldschmidt, G. Wu
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.
Waveguide and beam pipe field probes associated with a superconducting deflecting cavity are explored as beam position and tilt monitoring diagnostics. The superconducting deflecting cavity will be used for the Short-pulse X-rays (SPX) in the Advanced Photon Source (APS) upgrade project. Microwave Studio will be used to simulate the techniques of detecting the fields excited by the beam passing through the cavity and determining how close the beam is on electrical center.

MOPPR074

Using TE Wave Resonances for the Measurement of Electron Cloud Density

resonance, cavity, electron, 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.

MOPPR077

ION CHAMBERS AND HALO RINGS FOR LOSS DETECTION AT FRIB

radiation, ion, linac, cryomodule

969

Z. Liu
IUCF, Bloomington, Indiana, USA
D. Georgobiani, M.J. Johnson, M. Leitner, R.M. Ronningen, T. Russo, M. Shuptar, R.C. Webber, J. Wei, X. Wu, Y. Yamazaki, Y. Zhang, Q. Zhao
FRIB, East Lansing, Michigan, USA

Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661.
Unlike the high energy proton machines, our radiation transport simulation results show that it will be difficult to use traditional BLMs to detect beam losses for FRIB linac, not only due to the low radiation levels from low energy heavy ion beams, but also resulted by the cross talk effect from one part of the machine to another in the folded machine geometry. A device called “Halo Ring” is introduced as a component of the BLM system to substitute the traditional ion chamber in those regions.

MOPPR092

SVD-BASED METHOD FOR MEASUREMENT OF BEAM PARAMETERS AND FLAG RESOLUTION

emittance, quadrupole, booster, focusing

999

G.M. Wang, R.P. Fliller, I. Pinayev, T.V. Shaftan
BNL, Upton, Long Island, New York, USA

In NSLS II booster to storage ring transport line, the typical beam size in vertical plane is ~60 μm, which requires very high flag resolution to get good beam parameters measurement. This paper describes a new SVD-based method to measure transverse beam parameters and flag resolution simultaneously with double quads scan. Implementation simulations of the proposed method are performed for a dispersion free region in the NSLS-II booster to storage ring transport line. With this method, it breaks the limitation of beam parameters measurement accuracy duo to the flag resolution.

TUOAA01

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

plasma, electron, wiggler, 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]

TUOBC02

Small-Beta Collimation at SuperKEKB to Stop Beam-Gas Scattered Particles and to Avoid Transverse Mode Coupling Instability

interaction-region, impedance, scattering, coupling

1104

H. Nakayama, Y. Funakoshi, K. Kanazawa, K. Ohmi, Y. Ohnishi, Y. Suetsugu
KEK, Tsukuba, Japan
H. Nakano
Tohoku University, Graduate School of Science, Sendai, Japan

At SuperKEKB, beam particles which are Coulomb-scattered by the residual gas molecular change direction and will be eventually lost by hitting beam pipe inner wall. Due to large vertical beta function and small beam pipe radius just before IP, most of Coulomb-scattered particles are lost there and are very dangerous for the Belle-II detector. To stop such particles before the IP, vertical collimators are installed in the ring. However, such vertical collimators should be placed very close (few mm) to the beam and therefore induce transverse mode coupling instability. To avoid beam instability and achieve collimation at the same time, we need to install vertical collimators where vertical beta function is SMALL, since maximum collimator width determined by aperture condition is proportional to β^1/2, and minimum collimator width determined by instability is proportional to β^2/3. We present our strategy to stop beam-gas scattered particles and simulated loss rate in the interaction region. We will also show dedicated vertical collimator design to achieve less instability.

Slides TUOBC02 [2.196 MB]

TUEPPB001

Interaction of Muon Beam with Plasma Developed During Ionization Cooling

plasma, wakefield, electron, 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

electron, 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

TUEPPB003

Nonlinear Accelerator with Transverse Motion Integrable in Normalized Polar Coordinates

lattice, focusing, insertion, damping

1116

T.V. Zolkin
University of Chicago, Chicago, Illinois, USA
Y. Kharkov, I.A. Morozov
BINP SB RAS, Novosibirsk, Russia
S. Nagaitsev
Fermilab, Batavia, USA

Several families of nonlinear accelerator lattices with integrable transverse motion were suggested recently*. One of the requirements for the existence of two analytic invariants is a special longitudinal coordinate dependence of fields. This paper presents the particle motion analysis when a problem becomes integrable in the normalized polar coordinates. This case is distinguished from the others: it yields an exact analytical solution and has a uniform longitudinal coordinate dependence of the fields (since the corresponding nonlinear potential is invariant under the transformation from the Cartesian to the normalized coordinates). A number of interesting features are revealed: while the frequency of radial oscillations is independent of the amplitude, the spread of angular frequencies in a beam is absolute. A corresponding spread of frequencies of oscillations in the Cartesian coordinates is evaluated via the simulation of transverse Schottky noise.
V. Danilov and S. Nagaitsev, Phys. Rev. ST Accel. Beams 13 084002 (2010).

TUEPPB004

A Longitudinal Beam Dynamics Code for Proton Synchrotron

cavity, space-charge, synchrotron, bunching

1119

Y.S. Yuan, N. Wang, S. Wang, S.Y. Xu
IHEP, Beijing, People's Republic of China

The accelerator of China Spallation Neutron Source (CSNS) consists of an 80 MeV linac and a 1.6 GeV Rapid Cycling Synchrotron (RCS). Longitudinal beam dynamics study is one of the most important issues for RCS beam dynamics design. However, the existing codes cannot meet the requirement of longitudinal beam dynamics for CSNS/RCS. A new code has been developed for longitudinal beam dynamics design and simulation. The code can perform the voltage and phase curves design for non-sinusoidal magnetic field of dipole in an RCS cycle, with the fundamental RF mode and dual harmonic mode. The code can also be used for the beam simulation with longitudinal space charge effect, including the effects of higher order mode of RF cavities. By using the code, the longitudinal beam dynamics of CSNS/RCS was designed and optimized, and the simulation study with dual harmonics higher order modes of RF cavity was done, and the simulation results are presented.

TUEPPB006

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

electron, 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.

TUEPPB007

A Self Consistent Multiprocessor Space Charge Algorithm that is Almost Embarrassingly Parallel

space-charge, factory, collective-effects, brightness

1128

E.W. Nissen
JLAB, Newport News, Virginia, USA
B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA
S.L. Manikonda
ANL, Argonne, USA

Funding: Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We present a space charge code that is self consistent, massively parallelizeable, and requires very little communication between the computer nodes; making the calculation almost embarrassingly parallel. This method is implemented in the code COSY Infinity where the differential algebras used in this code are important to the algorithm's proper functioning. The method works by calculating the self consistent charge distribution using the statistical moments of the test particles, and converting them into polynomial series coefficients. These coefficients are combined with differential algebraic integrals to form the potential, and electric fields. The result is a transfer map which contains the effects of space charge. This method allows for massive parallelization since its statistics based solver doesn’t require any binning of the particles, and only requires a vector containing the partial sums of the statistical moments for the different nodes to be passed. All other calculations are done independently. The resulting maps can be used to analyze the system using normal form analysis, as well as advance particles in numbers and at speeds that were previously impossible.

TUEPPB013

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

electron, radiation, 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.

TUPPC006

CW Energy Upgrade of the Superconducting Electron Accelerator S-DALINAC

recirculation, dipole, linac, extraction

1161

M. Kleinmann, J. Conrad, R. Eichhorn, F. Hug, N. Pietralla
TU Darmstadt, Darmstadt, Germany

Funding: This work is supported by the DFG through SFB 634.
The S-DALINAC is a superconducting recirculating electron accelerator with maximum design energy of 130 MeV operating in cw at 3 GHz. Even so the gradients of the superconducting cavities are well above design, their design quality factor of 3*10⁹ have not been reached so far. Due to the limited cooling power of the cryo-plant being 120 W, the final energy achievable in cw operation is around 85 MeV, currently. In order to provide a cw beam with the designed final energy in the future, the installation of an additional recirculation path is projected and to be finished by 2013. We review the design constraints related to the existing beam lines, report in detail on the magnet design (being the key issue) and the lattice calculations for the additional recirculation path.

TUPPC011

Beam Steering Correction in FRIB Quarter-wave Resonators

cavity, linac, cryomodule, solenoid

1176

A. Facco
INFN/LNL, Legnaro (PD), Italy
A. Facco, Y. Xu, Y. Zhang, Q. Zhao, Z. Zheng
FRIB, East Lansing, Michigan, USA

Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
The Quarter-Wave Resonators (QWR) section of the FRIB superconducting driver linac is required to accelerate Uranium beam up to 16 MeV/u in two different charge states simultaneously. This puts severe requirements on resonators alignment and field quality, in order to avoid beam losses and emittance growth. In particular, QWR beam steering can cause transverse oscillations of the beam centroid which reduce the linac acceptance and induces emittance growth. We have studied, with an analytical model and with 3D beam dynamics simulations, correction methods for the FRIB QWRs steering. We found that cavity shifting can provide effective steering cancellation in FRIB QWRs without need of cavity shape modifications, and allows to eliminate transverse beam oscillations and to improve beam quality. Calculation and simulation methods and results will be presented and discussed.
Michigan State University designs and establishes FRIB as a DOE Office of Science National User Facility in support of the mission of the Office of Nuclear Physics.

TUPPC019

Beam Dynamics Simulations of J-PARC Main Ring for Damage Recovery from the Tohoku Earthquake in Japan and Upgrade Plan of Fast Extraction Operation

alignment, injection, acceleration, linac

1200

Y. Sato, K. Hara, S. Igarashi, T. Koseki, K. Ohmi, C. Ohmori
KEK, Ibaraki, Japan
H. Hotchi
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

Magnets of Japan Proton Accelerator Research Complex (J-PARC) were shaken by the Tohoku Earthquake in Japan on March 11th, 2011. The alignment of J-PARC Main Ring (MR) received 20 mm displacement horizontally and 6 mm vertically. Beam dynamics simulations were performed to estimate the effect of the displacement on closed orbit distortions and beam loss in fast extraction (FX) operation of J-PARC MR. Based on the simulation results, we concluded that re-alignment of J-PARC MR was needed to achieve high-power beam. The re-alignment of MR was finished on October 28th, 2011. We also considered the effects of the earthquake on the upstream of MR to establish our upgrade plan, which was based on beam dynamics simulations optimizing collimator balance of injection beam transport (3-50BT) and MR, and RF patterns. J-PARC MR FX operation was resumed from December 2011.

TUPPC020

A Scheme for Horizontal-vertical Coupling Correction at SuperKEKB

coupling, optics, lattice, target

1203

H. Sugimoto, H. Koiso, A. Morita, Y. Ohnishi, K. Oide
KEK, Ibaraki, Japan

SuperKEKB is an 7 GeV electron and 4 GeV positron double ring collider project based on the nano beam scheme and is aimed to break the world's luminosity record. A horizontal flat beam is essential to realize the nano beam collisions. One of critical effect that induces unexpected coupling is machine error, such as magnet misalignment and field imperfection. Coupling correction, therefore, plays key role in the actual beam operation. In this study, we numerically explore a possible scheme for coupling correction in the SuperKEKB lattice. Some coupling measurement and correction methods are applied to the model lattice considering magnet misalignments and finite BPM resolution. Based on the results, the attainable smallest coupling in the actual SuperKEKB is discussed.

TUPPC021

Design Study on KEK Injector Linac Upgrade for High-current and Low-emittance Beams

emittance, linac, wakefield, acceleration

1206

H. Sugimoto, M. Satoh, M. Yoshida
KEK, Ibaraki, Japan

Injector linac at KEK is now under upgrading to produce high current (5nC for e-, 4nC for e+) and low emittance (20 mm mrad for e-, 6 mm mrad for e+) electron and positron beams to a SuperB collider called SuperKEKB. Emittance growth resulted from both wakefield at the acceleration structure and dispersive effects at the focusing structure are troublesome in keeping the beam quality during the beam propagation. In this study, a possible solution to mitigate these effects in the KEK injector linac is explored by considering bunch compression in an existing bending section, orbit correction to suppress the wakefield excitation, and beam optics design.

TUPPC023

Waist Corrections at the Interaction Point of ATF2 in the Presence of IPBSM Fringe Rotations and Input Beam Sigma13, Sigma24

sextupole, coupling, quadrupole, alignment

1212

S. Bai, J. Gao
IHEP, Beijing, People's Republic of China
P. Bambade
LAL, Orsay, France

The ATF2 project is the final focus system prototype for ILC and CLIC linear collider projects, with a purpose to reach a 37nm vertical beam size at the interaction point. In beam tuning towards the goal beam size, the presence of a tilt of the IP Shintake monitor fringe pattern with respect to the x-y coordinate system of the beam (or equivalently a σ13 correlation), as well as a σ24 correlation, can break the orthogonality in the main σ34 and σ32 waist corrections during the minimization and result in larger vertical beam sizes at IP. Both effects are studied, analytically and in simulation, and a practical procedure is suggested for diagnosing the presence of a residual fringe tilt, by measuring the influence of the horizontal waist correction on the minimum vertical beam size.

TUPPC024

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

electron, solenoid, 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.

TUPPC026

Design of Compact C-Band Standing-Wave Accelerating Structure Enhancing RF Phase Focusing

coupling, bunching, cavity, focusing

1221

H.R. Yang, M.-H. Cho, J. Jang, S.H. Kim, W. Namkung, S.J. Park
POSTECH, Pohang, Kyungbuk, Republic of Korea
J.-S. Oh
NFRI, Daejon, Republic of Korea

Funding: Work supported by POSTECH Physics BK21 Program.
We design a C-band standing-wave accelerating structure for an X-ray source of the imaging and medical applications. It is capable of producing 6-MeV, 100-mA pulsed electron beams which is focused by less than 1.5 mm without external magnets. As an RF source, we use peak 1.5-MW magnetron with duty factor of 0.08%. The accelerating structure is a bi-periodic and on-axis-coupled structure with a built-in bunching section, which consists 3 bunching cells, 13 normal cells and a coupler cell. It operated with π/2-mode standing-waves. The bunching section is designed to enhance the RF phase focusing in order to achieve 1.2-mm beam spot size. Each cavity is designed with the MWS code to maximize the effective shunt impedance within 3.5% inter-cell coupling. In this paper, we present design details of RF cavities and the beam dynamics simulation by the PARMELA code.

TUPPC035

Design of a Surface Muon Beam Line for High Field muSR at the PSI Proton Accelerator Facility

quadrupole, focusing, proton, secondary-beams

1236

D. Reggiani, K. Deiters, P. Kaufmann, Y. Lee, T. Prokscha, T. Rauber, R. Scheuermann, K. Sedlak, V. Vranković
Paul Scherrer Institut, Villigen, Switzerland

Starting from 2012, a high field muSR (muon spin rotation/relaxation/resonance) facility will come into operation in the piE3 secondary beam line located at the target station E of the PSI proton accelerator. For this purpose, the last part of the beam line has been redesigned in order to integrate two electrostatic spin rotator devices providing a 90° rotation of the muon spin. At the same time, requirements of small beam diameter (σ ≈ 10 mm) as well as small momentum bite (δ_p/p ≈ 1%) in the sample region have to be met. This work focuses on the simulation of the beam optics (28 MeV/c design momentum). Particular concern is given to potential transmission losses caused by the spin rotator devices. The matching of the beam line with the high magnetic field up to 9.5 T surrounding the sample region has been considered as well. An overview of the spin rotator devices, specifically designed for this project, is also presented.

TUPPC045

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

cavity, coupling, klystron, electron

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.

TUPPC048

Online Physics Model Platform

controls, EPICS, lattice, monitoring

1275

P. Chu, Y. Zhang
FRIB, East Lansing, Michigan, USA
C. Benatti, V. Vuppala
NSCL, East Lansing, Michigan, USA
D. Dohan, G. Shen
BNL, Upton, Long Island, New York, USA
J. Wu
SLAC, Menlo Park, California, USA

Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
For a complex accelerator such as the Facility for Rare Isotope Beams (FRIB), a transfer matrix based online model might not be sufficient for the entire machine. On the other hand, if introducing another modelling tools, physics applications have to be rewritten for all modelling tools. A platform which can host multiple modelling tools would be ideal for such scenario. Furthermore, the model platform along with infrastructure support can be used not only for online applications but also for offline purposes with multi-particle tracking simulation. In order to achieve such a platform, a set of common physics data structures has to be set. XAL's accelerator hierarchy based data structure is a good choice as the common structure for various models. Application Programming Interface (API) for physics applications should also be defined within a model data provider. A preliminary platform design and prototype is discussed.

TUPPC049

A Tapered-foil Emittance-exchange Experiment at LANSCE

emittance, proton, scattering, collimation

1278

R.C. McCrady
LANL, Los Alamos, New Mexico, USA

We are planning an experiment at the Los Alamos Neutron Science Center (LANSCE) to demonstrate a technique for reducing the transverse emittance of the proton beam by passing the beam through a wedge-shaped energy degrader to produce a non-symplectic correlation between transverse position and energy, then removing this correlation with a bending magnet. This technique was proposed by Peterson* in 1983. We present a specific beamline layout that is expected to mitigate several complications associated with fielding an experiment to demonstrate the technique with a low-emittance proton beam. We present simulated results and expected outcomes of this demonstration.
* J. M. Peterson, Proc. of PAC 1983, pP. 2403-2405 (1984).

TUPPC051

FACET Tolerances for Static and Dynamic Misalignment

quadrupole, plasma, sextupole, wakefield

1284

J.T. Frederico, M.J. Hogan, T.O. Raubenheimer
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
The Facility for Advanced Accelerator and Experimental Tests (FACET) at the SLAC National Accelerator Laboratory is designed to deliver a beam with a transverse spot size on the order of 10 μm x 10 μm in a new beamline constructed at the two kilometer point of the SLAC linac. Commissioning the beamline requires mitigating alignment errors and their effects, which can be significant and result in spot sizes orders of magnitude larger. Sextupole and quadrupole alignment errors in particular can introduce errors in focusing, steering, and dispersion which can result in spot size growth, beta mismatch, and waist movement. Alignment errors due to static misalignments, mechanical jitter, energy jitter, and other physical processes can be analyzed to determine the level of accuracy and precision that the beamline requires. It is important to recognize these effects and their tolerances in order to deliver a beam as designed.

TUPPC052

Longitudinal Beam Tuning at FACET

linac, diagnostics, wakefield, klystron

1287

N. Lipkowitz, F.-J. Decker, J. Sheppard, S.P. Weathersby, U. Wienands, M. Woodley, G. Yocky
SLAC, Menlo Park, California, USA

Commissioning of the Facility for Advanced acCelerator Experimental Tests (FACET) at SLAC began in July 2011. In order to achieve the high charge density required for users such as the plasma wakefield acceleration experiment, the electron bunch must be compressed longitudinally from ~6 mm down to 20 microns. This compression scheme is carried out in three stages and requires careful tuning, as the final achievable bunch length is highly sensitive to errors in each consecutive stage. In this paper, we give an overview of the longitudinal dynamics at FACET, including beam measurements taken during commissioning, tuning techniques developed to minimize the bunch length, optimization of the new “W” chicane at the end of the linac, and comparison with particle tracking simulations. In addition, we present additional diagnostics and improved tuning techniques, and their expected effect on performance for the upcoming 2012 user run.

TUPPC058

Beam Energy Variation with Dipole Fault

dipole, sextupole, closed-orbit, lattice

1305

Y. Li, S. Krinsky
BNL, Upton, Long Island, New York, USA

Funding: Supported by Department of Energy Contract No. DE-AC02-98CH10886.
The effect of dipole faults and closed orbit correction on the beam energy is studied both analytically and numerically using the ELEGANT code. Motivated by top-off safety analysis, we consider the case of single dipole faults and study how large an error can be compensated by the closed orbit correction system before the beam is lost.

TUPPC060

Beam Optics and the pp2pp Setup of the STAR Experiment at RHIC

quadrupole, proton, optics, scattering

1311

P.H. Pile, W. Guryn, J.H. Lee, S. Tepikian, K. Yip
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 newly installed forward detector system at the STAR experiment at RHIC measures small angle elastic and inelastic scattering of polarized protons on polarized protons. The detector system makes use of a pair of Roman Pot (RP) detectors, instrumented with silicon detectors, and located on either side of the STAR intersection region downstream of the DX and D0 dipoles and quadrupole triplets. The parallel to point optics is designed so that scattering angles are determined from position measurements at the RP's with small error. The RP setup allows measurement of position and angle for a subset of the scattered protons. These measured position/angle correlations at the RP's can be compared with optics model predictions to get a measure of the accuracy of the quadrupole triplet current settings. The current in each quadrupole in the triplets is comprised of sums and differences of up to six power supplies and an overall 1% error in the triplet field strengths results in a 4% error in four-momentum transfer squared. This technique is also useful to check the polarity of the skew elements located in each quadrupole triplet. Results of the analysis will be presented.

TUPPC070

Alternating Spin Aberration Electrostatic Lattice for EDM Ring

lattice, quadrupole, proton, storage-ring

1332

Y. Senichev, R. Maier, D. Zyuzin
FZJ, Jülich, Germany
M. Berz
MSU, East Lansing, Michigan, USA

The idea of the electric dipole moment search using the storage ring (SrEDM) with polarized beam is realized under condition of the long-time spin coherency of all particles, the time during which the RMS spread of the spin orientation of all particles in the bunch reaches one radian. Following the requirements of the planned EDM experiment, the SCT should be more than 1000 seconds. During this time each particle performs about 10⁹ turns in the storage ring moving on different trajectories through the optics elements. At such conditions the spin-rotation aberrations associated with various types of space and time dependent nonlinearities start to play a crucial role. In this paper we consider a new method based on the alternating spin drift, causing it to rotate alternately, thereby limiting the growth of aberrations at one order of magnitude lower. As a result, using this method we can achieve the SCT of the order of 5000-6000 seconds. The difficulties of these studies are still in the fact that the aberrations growth observed in the scale of a 10⁹ turns. For the study we use an analytical method in composition with a numerical simulation by COSY Infinity.

TUPPC071

Comparison of Different Numerical Modelling Methods for Beam Dynamics in Electrostatic Rings

lattice, quadrupole, optics, proton

1335

D. Zyuzin, R. Maier, Y. Senichev
FZJ, Jülich, Germany
S.N. Andrianov, A.N. Ivanov
St. Petersburg State University, St. Petersburg, Russia
M. Berz
MSU, East Lansing, Michigan, USA

To search the electric dipole moment was proposed to use polarized protons at the so-called "magic" momentum of 0.7 GeV/c in an electric storage ring. For studying beam dynamics in electrostatic rings different computational methods can be used. We used differential algebra methods realized in COSY Infinity and integrating program with symplectic Runge-Kutta methods. These methods were observed and compared for orbital and spin motion.

TUPPC077

Numerical Study of Beam Trapping in Stable Islands for Simple 2D Models of Betatronic Motion

emittance, resonance, extraction, octupole

1350

M. Giovannozzi, C. Hernalsteens
CERN, Geneva, Switzerland

An essential ingredient for the proposed Multi-Turn Extraction (MTE) at the CERN PS is the beam trapping in stable islands. The control of the trapping process is essential for the quality of the final beam in terms of intensity sharing and emittance. In this paper, the splitting process is studied quantitatively by means of numerical simulations performed on 2D model representing the horizontal non-linear betatronic motion. The results are reviewed and discussed in details.

TUPPC079

Tracking LHC Models with Thick Lens Quadrupoles: Results and Comparisons with the Standard Thin Lens Tracking

quadrupole, lattice, optics, dipole

1356

M. Giovannozzi, H. Burkhardt, T. Risselada
CERN, Geneva, Switzerland

So far, the massive numerical simulation studies of the LHC dynamic aperture were performed using thin lens models of the machine. This approach has the clear advantage of speed, but it has also the disadvantage of requiring re-matching of the optics from the real thick configuration to the thin one. Furthermore, as the figure-of-merit for the re-matching is the agreement between the beta-functions for the two model, while the quadrupole gradients are left free parameters, the effect of the magnetic multipoles might be affected by this approach and in turn the dynamic aperture computation. In this paper the new approach is described and the results for the dynamic aperture are compared with the old approach, including detailed considerations on the CPU-time requirements.

TUPPC080

Investigations of Scaling Laws of Dynamic Aperture with Time for Numerical Simulations including Weak-Strong Beam-Beam Effects

injection, dynamic-aperture, beam-beam-effects, lattice

1359

M. Giovannozzi
CERN, Geneva, Switzerland
E. Laface
ESS, Lund, Sweden

A scaling law describing the time-dependence of the dynamic aperture, i.e., the region of phase space where stable motion occurs, was proposed in previous papers about ten years ago. It was shown that dynamic aperture has a logarithmic dependence on time, which would be suggested by some fundamental theorems of the theory of dynamical systems. So far, such a law was applied to single-particle effects only, i.e., the only source of non-linear effects was the magnetic imperfections. In this paper an attempt is made to extend the scaling law to the case of weak-strong beam-beam effects. The results of numerical simulations performed, including both non-linear magnetic imperfections and weak-strong beam-beam effects, are presented and discussed in detail.

TUPPC090

Beam Physics of Integrable Optics Test Accelerator at Fermilab

betatron, resonance, lattice, optics

1371

A. Valishev, S. Nagaitsev
Fermilab, Batavia, USA
V.V. Danilov
ORNL, Oak Ridge, Tennessee, 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.
Fermilab's Integrable Optics Test Accelerator is an electron storage ring designed for testing advanced accelerator physics concepts, including implementation of nonlinear integrable beam optics and experiments on optical stochastic cooling. The machine is currently under construction at the Advanced Superconducting Test Accelerator facility. In this report we present the goals and the current status of the project, and describe the details of machine design. In particular, we concentrate on numerical simulations setting the requirements on the design and supporting the choice of machine parameters.

TUPPC091

Simulation of Colliding Beams with Feedback in LHC

emittance, feedback, luminosity, kicker

1374

S. Paret, J. Qiang
LBNL, Berkeley, California, USA

Funding: This work supported partially by the US LHC Accelerator Research Program (LARP) of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Beam-beam effects impose restrictions on beam and beam optical parameters as they may degrade the luminosity and the emittance or cause coherent instabilities and particle loss. In the planned High Luminosity Large Hadron Collider (HL-LHC), beam-beam effects will significantly affect the beams because of unprecedented beam parameters and new features like crab cavities or elliptical beam cross sections at the interaction points. Noise from various sources can further worsen the situation. Therefore investigations are required to identify limitations of possible HL-LHC layouts. The impact of beam-beam effects on the beam dynamics is investigated by virtue of particle tracking simulations. Using the code BeamBeam3D and the strong-strong collision model, simulations including perturbations by noise and LHC's feedback system, an important means to mitigate transverse emittance growth due to coherent beam excitation, were carried out. The impact of numerical noise on the emittance in simulations and the state of the feedback modeling are presented.

TUPPC097

Computational Modeling of Electron Cloud For MEIC

electron, 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.

TUPPC101

A Model of the AGS Based on Stepwise Ray-Tracing Through the Measured Field Maps of the Main Magnets

resonance, quadrupole, sextupole, focusing

1395

Y. Dutheil, F. Méot, N. Tsoupas
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.
Two dimensional mid-plane magnetic field maps of two of the main AGS magnets were produced, from Hall probe measurements, for a series of different current settings. The analysis of these data yielded the excitation functions and harmonic coefficients of the main magnets [BNL TN 424 & TN 429] which have been used so far in all the models of the AGS. The constant increase of computation power makes it possible today to directly use stepwise ray-tracing through these measured field maps with a reasonable computation time. We describe in detail how these field maps have allowed generation of models of the 6 different types of AGS main magnets, and how they are being handled with the Zgoubi ray-tracing code. We give and discuss a number of results so obtained regarding both beam and spin dynamics in the AGS, and provide comparisons with other numerical and analytical modeling methods.

TUPPC102

Simulation Study of Beam-beam Effects in Ion Beams with Large Space Charge Tuneshift

space-charge, lattice, synchrotron, collider

1398

C. Montag
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.
During low-energy operations with gold-gold collisions at 3.85 GeV beam energy, significant beam lifetime reductions have been observed due to the beam-beam interaction in the presence of large space charge tuneshifts. These beam-beam tuneshift parameters were about an order of magnitude smaller than during regular high energy operations. To get a better understanding of this effect, simulations have been performed. Recent results are presented.

TUPPC103

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

electron, proton, luminosity, ion

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.

TUPPD003

Optimisation of Cooling Lattice Based on Bucked Coils for the Neutrino Factory

lattice, factory, emittance, cavity

1407

A. Alekou, J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

The ionisation cooling technique will be used at the Neutrino Factory to reduce the transverse phase space of the muon beam. For efficient cooling, high average RF gradient and strong focusing are required to be applied in the cooling channel. However, high magnetic field at the position of the RF cavities induces electric field breakdown and therefore, a novel configuration, the Bucked Coils lattice, has been proposed to mitigate this problem. The Bucked Coils lattice has significantly lower magnetic field in the RF cavities by using coils of different radius and opposite polarity. This paper presents the optimisation of this lattice, its cooling performance, together with the preliminary conceptual engineering design.

TUPPD007

Multiple Scattering Measurements in the MICE Experiment

scattering, emittance, solenoid, factory

1419

T. Carlisle, J.H. Cobb
JAI, Oxford, United Kingdom
D.V. Neuffer
Fermilab, Batavia, USA

The international Muon Ionization Cooling Experiment (MICE), under construction at RAL, will test and characterize a prototype cooling channel for a future Neutrino Factory or Muon Collider. The cooling channel aims to achieve, using liquid hydrogen absorbers, a 10% reduction in transverse emittance. The change in 4D emittance will be determined with a relative accuracy of 1% by measuring muons individually. Muon detectors include two scintillating fibre trackers embedded within 4 T solenoid fields, TOF counters and a muon ranger. Step IV of MICE will begin in 2012, producing the experiment's first precise emittance-reduction measurements. Multiple scattering in candidate Step IV absorber materials was studied in G4MICE, based on GEANT4. Equilibrium emittances for low-Z materials from hydrogen to aluminium can be studied experimentally in Step IV of MICE, and compared with simulations.

TUPPD010

Helical Muon Beam Cooling Channel Engineering Design

cavity, solenoid, beam-cooling, collider

1425

G. Flanagan, R.P. Johnson, G.M. Kazakevich, F. Marhauser, M.L. Neubauer
Muons, Inc, Batavia, USA
V.S. Kashikhin, M.L. Lopes, G.V. Romanov, M.A. Tartaglia, K. Yonehara, M. Yu, A.V. Zlobin
Fermilab, Batavia, USA

Funding: Supported in part by DOE STTR Grant DE-SC0006266
The Helical Cooling Channel (HCC), a novel technique for six-dimensional (6D) ionization cooling of muon beams, has shown considerable promise based on analytic and simulation studies. However, the implementation of this revolutionary method of muon cooling requires new techniques for the integration of hydrogen-pressurized, high-power RF cavities into the low-temperature superconducting magnets of the HCC. We present the progress toward a conceptual design for the integration of 805 MHz RF cavities into a 10 T Nb3Sn based HCC test section. We include discussions on the pressure and thermal barriers needed within the cryostat to maintain operation of the magnet at 4.2 K while operating the RF and energy absorber at a higher temperature. Additionally, we include progress on the Nb3Sn helical solenoid design

TUPPD011

Studies of the Twin Helix Parametric-resonance Ionization Cooling Channel with COSY INFINITY

resonance, emittance, quadrupole, collider

1428

J.A. Maloney, K.B. Beard, R.P. Johnson
Muons, Inc, Batavia, USA
A. Afanasev
GWU, Washington, USA
S.A. Bogacz, Y.S. Derbenev, V.S. Morozov
JLAB, Newport News, Virginia, USA
B. Erdelyi
Northern Illinois University, DeKalb, Illinois, USA

Funding: Supported in part by SBIR Grant DE-SC00005589. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A primary technical challenge to the design of a high luminosity muon collider is an effective beam cooling system. An epicyclic twin-helix channel utilizing parametric-resonance ionization cooling has been proposed for the final 6D cooling stage. A proposed design of this twin-helix channel is presented that utilizes correlated optics between the horizontal and vertical betatron periods to simultaneously focus transverse motion of the beam in both planes. Parametric resonance is induced in both planes via a system of helical quadrupole harmonics. Ionization cooling is achieved via periodically placed wedges of absorbing material, with intermittent rf cavities restoring longitudinal momentum necessary to maintain stable orbit of the beam. COSY INFINITY is utilized to simulate the theory at first order. The motion of particles around a hyperbolic fixed point is tracked. Comparison is made between the EPIC cooling channel and standard ionization cooling effects. Cooling effects are measured, after including stochastic effects, for both a single particle and a distribution of particles.

TUPPD012

Complete Muon Cooling Channel Design and Simulations

emittance, dipole, solenoid, collider

1431

C. Y. Yoshikawa, C.M. Ankenbrandt, R.P. Johnson
Muons, Inc, Batavia, USA
Y.S. Derbenev, V.S. Morozov
JLAB, Newport News, Virginia, USA
D.V. Neuffer, K. Yonehara
Fermilab, Batavia, USA

Considerable progress has been made in developing promising subsystems for muon beam cooling channels to provide the extraordinary reduction of emittances required for an energy-frontier muon collider. However, it has not yet been demonstrated that the various proposed cooling subsystems can be consolidated into an integrated end-to-end design. Presented here are concepts to address the matching of transverse emittances between subsystems through an extension of the theoretical framework of the Helical Cooling Channel (HCC), which allows a general analytical approach to guide the transition from one set of cooling channel parameters to another.

TUPPD013

Bunch Coalescing in a Helical Channel

collider, acceleration, emittance, factory

1434

C. Y. Yoshikawa, C.M. Ankenbrandt
Muons, Inc, Batavia, USA
D.V. Neuffer, K. Yonehara
Fermilab, Batavia, USA

Funding: Supported in part by SBIR Grant 4725 · 09SC02739.
A high-luminosity Muon Collider requires bunch recombination for optimal luminosity. In this paper, we take advantage of the large slip factor in a helical transport channel (HTC) to coalesce bunches of muons into a single one over a shorter distance than can be achieved over a straight channel. The coalescing subsystem that is designed to merge 9 bunches has a horizontal length of ~105m and is able to achieve efficiencies of 99.7%, 98.4%, and 94.2% for 9, 11, and 13 bunches, respectively, where each bunch has emittances expected at the end of an HCC. Simplified designs incorporating fill factors for RF cavities of ~25% and ~50% obtained efficiencies of 96%, 94-95%, and 90-91% for 9, 11, and 13 bunches, respectively. The efficiencies above do not include decay losses, which would be ~8% for muons with kinetic energy of 200 MeV.

TUPPD024

HIGH-INTENSITY LOW-ENERGY POSITRON SOURCE AT JEFFERSON LABORATORY

target, positron, solenoid, radiation

1461

S. Golge, B. Vlahovic
NCCU, Durham, USA
B. Wojtsekhowski
JLAB, Newport News, Virginia, USA

We present a novel concept of a low-energy e⁺ source with projected intensity on the order of 10¹⁰ slow e+/s. The key components of this concept are a continuous wave e^- beam, a rotating positron-production target, a synchronized raster/anti-raster, a transport channel, and extraction of e⁺ into a field-free area through a magnetic plug for moderation in a cryogenic solid. Components were designed in the framework of GEANT4-based (G4beamline) Monte Carlo simulation and TOSCA magnetic field calculation codes. Experimental data to demonstrate the effectiveness of the magnetic plug is presented.

TUPPD031

Novel Techniques for Isotope Harvesting at FRIB

optics, ion, target, resonance

1470

M.A.C. Cummings
Muons, Inc, Batavia, USA
L.L. Bandura
FRIB, East Lansing, Michigan, USA

Exotic isotopes have applications in medicine, industry, and national security. Historically, the U.S. has relied on foreign sources for these isotopes. FRIB will be a domestic source of these isotopes. While FRIB is mainly focused on producing exotic isotopes for basic nuclear physics experiments, it also offers an opportunity to harvest unused isotopes for other applications. It is critical that isotope harvesting take place in a synergistic manner that does not adversely affect experiments that will be simultaneously taking place at the facility. Beam optics schemes will be calculated to determine the best locations and methods of separation. These calculations will use COSY Monte Carlo and G4beamline in conjunction with other state of the art ion optical codes that simulate isotope dynamics in magnetic fields and in matter. The results of these simulations will be used to determine the best beam-target combinations to produce the isotopes that are most in-demand and calculate purities of these isotopes in multiple locations in the fragment separators. Trapping and extraction schemes will also be described to maximally recover pure isotope samples.

TUPPD032

Design Optimization of Flux Concentrator for SuperKEKB

positron, solenoid, target, electron

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.

TUPPD037

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

electron, plasma, proton, 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.

TUPPD039

Simulation Study of Space Charge Effects for a 100-keV, 150-mA Class Deuteron Source

emittance, extraction, plasma, focusing

1491

M. Ichikawa, H. Suzuki
Japan Atomic Energy Agency (JAEA), International Fusion Energy Research Center (IFERC), Rokkasho, Kamikita, Aomori, Japan
S. Maebara
JAEA, Ibaraki-ken, Japan

Ion sources providing high current beam with low emittance are required for accelerators to expand to apply them to fusion material science. A 100-keV, 150-mA class deuteron source with low emittance is required for an accelerator-based neutron irradiation facility to develop fusion materials, and the study for space charge effects in the range of a 20- to 150-mA deuteron beam is indispensable to extract the low beam emittance. For this purpose, each ion source to extract the beam current of 20, 50, 100, and 150 mA was designed by the Igun code, under the condition to extract a beam radius of 4 mm, a beam energy of 100 keV, and a normalized emittance of 0.2 PI mm mrad. In this article, these simulation results from the viewpoint of space charge effects will be presented in detail.

TUPPD055

Characterization of ps-spaced Comb Beams at SPARC

linac, radiation, bunching, laser

1527

A. Mostacci
URLS, Rome, Italy
A. Bacci, A.R. Rossi
Istituto Nazionale di Fisica Nucleare, Milano, Italy
M. Bellaveglia, E. Chiadroni, G. Di Pirro, M. Ferrario, G. Gatti, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma), Italy

SPARC in Frascati is a high brightness photo-injector used to explore advanced beam manipulation techniques. Sub-picosecond, high brightness electron bunch trains (the so called comb beam) can be generated illuminating the cathode of a RF photoinjector with a laser pulse train and via velocity bunching technique. In this paper different aspects of the physics of this advanced beam manipulation technique are discussed combining simulation and measurements. Beam dynamics numerical macroparticle simulations have been compared with the experimental results for model validation; they allow to gain insights on the beam evolution highlighting several aspects which can not be measured. In particular, we focus on the train evolution in the linac sections and in the dog-leg line up to the THz station and on the effective rms length of the single pulses within the train when it becomes shorter than the resolution.

TUPPD058

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

gun, electron, cavity, cathode

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.

TUPPD062

The Source of Emittance Dilution and photoemission tunneling effect in Photocathode RF Guns

cathode, emittance, laser, cavity

1542

V. Volkov
BINP SB RAS, Novosibirsk, Russia
R. Barday, T. Kamps, J. Knobloch, A.N. Matveenko, S.G. Schubert, J. Völker
HZB, Berlin, Germany
J.K. Sekutowicz
DESY, Hamburg, Germany

Funding: Work supported by Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association VH-NG-636 and HRJRG-214.
Experimental data on HoBiCaT SRF photoinjector give an emittance which is much larger than the predicted thermal emittance. Modeling of photocathode RF gun beams with the different imperfections of experimental setup (alignment errors, inhomogeneity of quantum efficiency and laser power distributions on the cathode) is given. The main reason for the beam emittance dilution is photocathode field imperfections induced by field emitters that change the local electric field. Some field models of such photocathodes are tested in the simulations. The dependence of photocathode beam currents on the surface electric field was measured with the HoBiCaT SRF Photoinjector. The dependence can be explained by the tunneling effect described by Fowler-Nordheim like equation and is difficult to explain by usually applying Schottky effect.

TUPPD063

Interpretation of Dark Current Experimental Results in HZB SC RF Gun

cavity, accelerating-gradient, gun, HOM

1545

V. Volkov
BINP SB RAS, Novosibirsk, Russia
R. Barday, T. Kamps, J. Knobloch, A.N. Matveenko, A. Neumann
HZB, Berlin, Germany

Funding: Work supported by Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association VH-NG-636 and HRJRG-214.
The experimental dark current measurement results are obtained on HZB SC RF gun. The field emitters are considered to be random defects on the back wall of the cavity. Conducting wires with 1 micron length, blobs of 200 micron diameter and ”tip on tip” combination of them are taken as dark current emitters in the cavity. RF fields were calculated with CLANS program. The dynamic simulation of dark currents from these emitters fit experimental data. The emitter heating power by RF induced current is four orders of magnitude larger than by the field emitted dark current. The RF induced emitter temperature is proportional to ω1/2 which explains the accelerating gradient limit of a cavity like Kilpatrik law. The RF processing by high order modes seems to be promising.

TUPPD075

Simulated Performance of the Wisconsin Superconducting Electron Gun

emittance, solenoid, quadrupole, focusing

1572

R.A. Bosch, K.J. Kleman
UW-Madison/SRC, Madison, Wisconsin, USA
R.A. Legg
JLAB, Newport News, Virginia, USA

The Wisconsin superconducting electron gun is modeled with multiparticle tracking simulations using the ASTRA and GPT codes. To specify the construction of the emittance-compensation solenoid, we studied the dependence of the output bunch's emittance upon the solenoid's strength and field errors. We also evaluated the dependence of the output bunch's emittance upon the bunch's initial emittance and the size of the laser spot on the photocathode. The results suggest that a 200-pC bunch with an emittance of about one mm-mrad can be produced for a free-electron laser.

TUPPD082

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

electron, cathode, gun, 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.

TUPPP011

Simulations of Fringe Fields and Multipoles for the ANKA Storage Ring Bending Magnets

multipole, optics, sextupole, storage-ring

1626

M. Streichert, M.J. Nasse
Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
V. Afonso Rodriguez, A. Bernhard, N. Hiller, E. Huttel, V. Judin, B. Kehrer, M. Klein, S. Marsching, C.A.J. Meuter, A.-S. Müller, M. Schwarz, N.J. Smale
KIT, Karlsruhe, Germany

Funding: This work has been supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320.
ANKA is the synchrotron light source of the Karlsruhe Institute of Technology (KIT). With a maximum particle energy of 2.5 GeV, the storage ring lattice consists of 16 bending magnets with a nominal magnetic flux density of 1.5 T. For the beam dynamics simulations the consideration of the fringe fields and multipoles is essential. A reference measurement of the longitudinal magnetic flux density profile of a bending magnet exists for a current of 650 A, corresponding to a particle energy of 2.46 GeV. For lower beam energies where the magnets are no longer close to saturation, however, the exact density profiles may vary significantly. In order to derive fringe fields and multipole components for different beam energies, simulations of the magnetic flux density for different beam energies were conducted using a finite element method (FEM). We present the results of the simulations and demonstrate the improvements of the beam dynamics simulations in AT (Accelerator Toolbox).

TUPPP012

Optimization of the Beam Optical Parameters of the Linac-based Terahertz Source FLUTE

laser, gun, space-charge, linac

1629

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

Funding: Karlsruher Institut für Technologie.
FLUTE is a compact accelerator (consisting of a 7 MeV laser gun, a 50 MeV linac, and bunch compressors) under construction at KIT in Karlsruhe for producing coherent THz radiation. The programs ASTRA and CSRtrack were used to optimize the beam parameters. The aim was to minimize the bunch length used in various THz experiments, with bunch charges between 100 pC and 3 nC. It was calculated that the bunch length after compression depends both on the bunch current and the transverse beam size. The transverse beam size depends on the laser spot size at the cathode of the 7 MeV laser gun. Further simulations showed that a larger beam size reduces the efficiency of the compressor. This problem is cured by focusing elements with a focusing strength depending on the space charge after the gun and integrated into the various compressors layouts under study (four magnets, two magnets and quadrupoles, etc.). The results of these calculations are presented in this paper.

TUPPP036

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

radiation, electron, 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.

TUPPP042

Passive Landau Cavity Effects in the NSLS-II Storage Ring

cavity, storage-ring, impedance, wakefield

1701

G. Bassi, A. Blednykh, S. Krinsky
BNL, Upton, Long Island, New York, USA

Funding: Work supported by DOE contract No: DE-AC02-98CH10886.
In new 3rd generation synchrotron light sources with small transverse emittance, higher harmonic cavities (Landau cavities) are installed for bunch lengthening to increase the Touschek lifetime, and to provide Landau damping for beam stability. In this contribution we study the effects of passive Landau cavities in the NSLS-II storage ring for arbitrary fill-patterns with the OASIS tracking code.

TUPPP043

Analysis of Coupled Bunch Instabilities in the NSLS-II Storage Ring with a 7-cell PETRA-III RF Structure

HOM, impedance, cavity, damping

1704

G. Bassi, A. Blednykh, S. Krinsky, J. Rose
BNL, Upton, New York, USA

Funding: Work supported by DOE contract No: DE-AC02-98CH10886.
A 7-cell PETRA-III cavity is considered to be installed for the commissioning Phase 1 in the NSLS-II storage ring at an average current of 25mA. In this contribution we study transverse and longitudinal coupled-bunch instabilities that may be driven by the higher order modes of the 7-cell PETRA-III cavity. The instability thresholds are calculated with the OASIS tracking code, with parameters of the bare lattice (no damping wigglers and Landau cavities). We study multibunch configurations with arbitrary fill-patterns and discuss the slow head-tail effect at positive chromaticity to increase the transverse instability thresholds.

TUPPP048

Increasing the Spectral Range of the CLIO Infrared FEL User Facility by Reducing Diffraction Losses

undulator, vacuum, FEL, laser

1709

J.-M. Ortega, G. Perilhous, R. Prazeres
LCP/CLIO, Orsay, Cedex, France
H.B. Abualrob, P. Berteaud, L. Chapuis, M.-E. Couprie, T.K. El Ajjouri, F. Marteau, J. Vétéran
SOLEIL, Gif-sur-Yvette, France
J.P. Berthet, F. Glotin
CLIO/ELISE/LCP, Orsay, France

Funding: CNRS/RTRA
The infrared free-electron laser offers a large tunability since the FEL gain remains high throughout the infrared spectral range, and the reflectivity of metal mirrors remains also close to 1. The main limitation comes from the diffraction of the optical beam due to the finite size of the vacuum chamber of the undulator. At CLIO, we have obtained previously* an FEL tunable from 3 to 150 μm by operating the accelerator between 50 and 14 MeV. However, we found that a phenomenon of “power gaps“ is observed in far-infrared : the laser power falls down to zero at some particular wavelengths, whatever the beam adjustments are. We showed that this effect is related to to the waveguiding effect of the vacuum chamber leading to different losses and power outcoupling at different wavelengths**. To alleviate this effect we have designed a new undulator allowing to use a larger vacuum chamber without reducing the spectral tunability and agility of the FEL. From simulations, a large increase of available power is expected in far-infrared. The new undulator has been installed and its performances and first FEL measurement in far-infrared will be presented
* J.M. Ortega, F. Glotin, R. Prazeres
Infrared Physics and Technology, 49, 133 (2006)
** R. Prazeres, F. Glotin, J.-M. Ortega
Phys. Rev. STAB12, 010701 (2009)

TUPPP053

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

laser, emittance, electron, 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.

TUPPP057

Design of a Wavelength Continuously Tunable Ultraviolet Coherent Light Source

FEL, laser, radiation, undulator

1727

T. Zhang, D. Wang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
X.M. Yang
DICP, Dalian, People's Republic of China

Funding: Work supported by National Natural Science Foundation of China (Grant No. 11075199)
Dalian Coherent Light Source (DCL) is a proposed FEL-based novel light source user facility, will be located in Dalian city, China. DCL will mainly servers on the field of molecular reaction dynamics, ultra-fast physical chemistry experiments, etc. Running on the High-Gain-Harmonic-Generation (HGHG) FEL mode, DCL is expected to cover the FEL wavelength from 50 nm to 150 nm, with the help of continuously tuning Optical Parametric Amplification (OPA) seed laser system, which wavelength can be varied between 240 nm and 360 nm. Numerical simulation shows that the FEL pulse energy of DCL can surpass 100 μJ, at the whole full range wavelength with the undulator tapering technology, and the photon number can be up to 10¹³ per pulse, which is sufficient for user experiments.

TUPPP062

Start to End Simulation of Three Bunch Compressor Lattice for PAL XFEL

lattice, FEL, emittance, linac

1738

H.-S. Kang, M.-H. Cho, J.H. Han, T.-H. Kang, I.S. Ko
PAL, Pohang, Kyungbuk, Republic of Korea
C.H. Yi
POSTECH, Pohang, Kyungbuk, Republic of Korea

The PAL XFEL is a 0.1-nm hard X-ray FEL project starting from 2011 to finish in 2014, which aims at achieving higher photon flux than 10¹² photons/pulse at 0.1 nm using a 10 GeV electron linac. The PAL XFEL is designed to have a hard x-ray undulator line at the end of linac and a branch line at 2.65 GeV point for soft X-ray undulator line. The three bunch compressor lattice (3-BC) is chosen to minimize emitance growth due to CSR and minimize correlated energy spread. The 3-BC lattice makes it possible to operate soft X-ray FEL undulator line simultaneously and independently from hard X-ray FEL undulator line.

TUPPP063

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

linac, electron, emittance, 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.

TUPPP064

Microbunching Instability Studies in SwissFEL

laser, booster, FEL, linac

1744

S. Bettoni, B. Beutner
Paul Scherrer Institut, Villigen, Switzerland
V.A. Goryashko
NASU/IRE, Kharkov, Ukraine

Shot noise or an initial intensity modulation in the beam pulse may have a strong effect in the FEL linacs and also severely degrade the machine performances in terms of FEL performances. In this paper we present the simulations done to study this effect in SwissFEL, the future free electron laser under design at Paul Scherrer Institute. In particular we calculated the gain of the microbunching instability in the low and high energy part and we performed start-to-end simulations using as initial distribution something as close as possible to the laser profile measured at the SwissFEL injector test facility. We finally present the preliminary calculations to estimate the effect of the laser heater to mitigate this effect.

TUPPP074

Beam Dynamics Studies of a High-repetition Rate Linac Driver for a 4th-generation Light Source

FEL, emittance, linac, laser

1771

M. Venturini, J.N. Corlett, P. Emma, C. F. Papadopoulos, G. Penn, M. Placidi, J. Qiang, M.W. Reinsch, F. Sannibale, C. Steier, R.P. Wells
LBNL, Berkeley, California, USA

We present progress toward the design of a super-conducting linac driver of a high repetition rate FEL-based soft x-ray light source. The machine is intended to accept beams generated by the APEX* photocathode gun, operating in the MHz range, and deliver them to an array of SASE and seeded FEL beamlines. After reviewing the beam-dynamics considerations that are informing specific lattice choices we discuss the expected performance of the proposed machine design and its ability to meet the desired FEL specifications. We consider the merit of possible alternate designs (e.g., a one-stage compressor vs. a two-stage compressor) and the trade-offs between competing demands on the beam attributes (e.g., high peak current vs. acceptable energy spread).
* F. Sannibale et al., this conference.

TUPPP084

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

electron, radiation, undulator, FEL

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.

TUPPP088

Bunch Compressor Design for Potential FEL Operation at eRHIC

FEL, emittance, electron, 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.

TUPPR001

Spin Tracking Simulation of a Future International Linear Collider

polarization, positron, solenoid, electron

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.

TUPPR011

Six-dimensional Bunch Merging for Muon Collider Cooling

emittance, kicker, collider, solenoid

1831

R.B. Palmer, R.C. Fernow
BNL, Upton, Long Island, New York, USA
D.V. Neuffer
Fermilab, Batavia, USA

Funding: Work supported by US Department of Energy under contracts DE-AC02-98CH10886 and DE-AC02-07CH11359.
Muons for a Muon Collider are diffusely produced from pion decay. They are first phase rotated into a trains of bunches. The trains are ionization cooled in all six dimensions until they can be merged into single bunches, one of each sign. They are then further cooled in six dimensions before acceleration and injection into the collider. This merging matches more efficiently into the second phase of cooling if the merging is also in six dimensions. A scheme to do this is proposed. Groups of 3, of the initial 12, bunches are merged longitudinally into 4 longer bunches, using rf with multiple harmonics. These 4 are then kicked into 4 separate (trombone) channels of different lengths to bring them to closely packed transverse locations at the same time. Here they are captured into a single bunch with now increased transverse emittance.

TUPPR012

Polarized Positron Source with a Compton Multiple Interaction Point Line

positron, electron, laser, 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.

TUPPR015

Choke-Mode Damped Structure Design for the CLIC Main Linac

wakefield, damping, impedance, dipole

1840

H. Zha, H. Chen, W.-H. Huang, C.-X. Tang
TUB, Beijing, People's Republic of China
A. Grudiev, J. Shi, W. Wuensch
CERN, Geneva, Switzerland

Choke-mode damped accelerating structures are being studied as an alternative to the CLIC waveguide damped baseline structure. Choke-mode structures hold the potential for much lower pulsed surface heating and reduced cost since no milling is required. We propose a new choke geometry which has significant suppression of higher order dipoles. By impedance matching and detuning of the first dipole pass-band, the wakefield suppression is comparable to the baseline design with waveguide damping. A fully featured choke mode structure with the same accelerating gradient profile and filling time as the nominal CLIC design has been designed. It has the potential to replace the waveguide damped design without changing any of the machine layout or the beam parameters.

TUPPR017

Nonlinear Post-Linac Energy Collimation System for the Compact Linear Collider

sextupole, collimation, luminosity, octupole

1846

J. Resta-López, A. Faus-Golfe
IFIC, Valencia, Spain

Funding: FPA2010-21456-C02-01
The post-linac energy collimation system of the Compact Linear Collider (CLIC) has been designed to provide protection of the Beam Delivery System (BDS) against off-energy and mis-steered beams. The conventional baseline design consists of a two stage spoiler-absorber scheme. The CLIC energy collimators are required to withstand the impact of a full bunch train. This condition makes the energy collimator design very challenging, since the collimators have to deal with a total beam power of 14 MW at nominal energy and intensity. The increase of the transverse spot size at the collimators using nonlinear magnets could be a potential solution to guarantee the survivability of the collimators. In this paper we present an alternative nonlinear optics design for the CLIC energy collimation system. Possibilities for its optimization are discussed in view of performance simulation results.

TUPPR018

Beam Impedance Study of the Stripline Kicker for the CLIC Damping Ring

impedance, coupling, kicker, damping

1849

C. Belver-Aguilar, A. Faus-Golfe
IFIC, Valencia, Spain
M.J. Barnes
CERN, Geneva, Switzerland
I. Podadera, F. Toral
CIEMAT, Madrid, Spain

Funding: FPA2010-21456-C02-01
CLIC Pre-Damping (PDR) and Damping Rings (DR) are required for reducing the emittance of the electron and positron beams before being accelerated in the main linac. Several stripline kicker systems are used to inject and extract the beam from the PDR and DR. Wakefields produced by the charged particles when passing through the aperture of the stripline kickers may become an important source of emittance growth; for this reason, simulations of longitudinal and transverse beam impedance in the frequency domain, and their equivalent in the time domain are needed. First analytical approaches, future simulations and tests planned are presented in this paper.

TUPPR019

High Power Operation with Beam of a CLIC PETS Equipped with ON/OFF Mechanism

recirculation, extraction, controls, vacuum

1852

I. Syratchev, R. Corsini, A. Dubrovskiy, P.K. Skowroński
CERN, Geneva, Switzerland
R.J.M.Y. Ruber
Uppsala University, Uppsala, Sweden

One of the feasibility issues of the CLIC two-beam scheme is the possibility of rapidly switching off the RF power production in individual Power Extraction and Transfer Structures (PETS) in case of breakdowns, either in the PETS or one of the main beam accelerating structures. The proposed solution is to use a variable external reflector connected to the PETS. When activated, this scheme allows us to manipulate gradually the RF power transfer to the accelerating structure and to reduce the RF power production in the PETS itself by a factor of 4. Recently the first operation of the Two Beam Test Stand (TBTS) PETS equipped with an on-off mechanism has been performed in CTF3. In this paper we will present the results of the PETS operation when powered by the drive beam up to high peak power levels (>100 MW) and compare them to expectations.

TUPPR020

Updates to the CLIC Post-collision Line

radiation, scattering, shielding, background

1855

L.C. Deacon
CERN, Geneva, Switzerland

The 1.5 TeV Compact Linear Collider (CLIC) beams, with a total power of 14 MW per beam, are disrupted at the interaction point due to the very strong beam-beam effect. The disrupted beam has a power of 10 MW. Some 3.5 MW reaches the main dump in the form of beamstrahlung photons, and about 0.5 MW of e⁺ and e^- coherent pair particles with a very broad energy spectrum as well as the lower energy disrupted beam particles need to be disposed of along the post collision line. Calculations for the energy deposition in the magnet coils and the resulting magnet lifetimes for various shielding configurations are presented.

TUPPR027

Study of Multipolar RF Kicks from the Main Deflecting Mode in Compact Crab Cavities for LHC

cavity, multipole, dipole, coupling

1873

A. Grudiev, J. Barranco, R. Calaga, R. De Maria, M. Giovannozzi, R. Tomás
CERN, Geneva, Switzerland

A crab cavity system is under design in the frame work of the High Luminosity LHC project. Due to transverse space constraints on one hand and the RF frequency requirements on the other hand, the design of the crab cavities has to be compact. This results in the crab cavity shape being far from axially symmetric and, as a consequence, higher order multipolar components of the main deflecting mode are non-zero. In this paper, multipolar RF kicks from the main deflecting mode have been calculated in the compact crab cavities for LHC. They are compared to the multipolar error in magnetic elements of LHC. The influence of the RF kicks on the beam dynamics has been investigated and possible acceptable tolerances are presented.

TUPPR028

Recent Improvements in the Orbit Feedback and Ground Motion Mitigation Techniques for CLIC

luminosity, quadrupole, feedback, ground-motion

1876

J. Snuverink, J. Pfingstner, D. Schulte
CERN, Geneva, Switzerland

The Compact Linear Collider (CLIC) accelerator has strong stability requirements on the position of the beam. In particular, the beam position will be sensitive to ground motion. A number of mitigation techniques have been proposed - quadrupole stabilization and positioning, final doublet stabilization as well as beam based orbit and interaction point (IP) feedback. Integrated studies of the impact of ground motion on the CLIC Main Linac (ML) and Beam Delivery System (BDS) that model the latest hardware designs have been performed. Furthermore, additional imperfections have been introduced and the robustness of this system is discussed in detail. The possibility of using ground motion measurements as an alternative to the quadrupole stabilization is investigated.

TUPPR029

Performance of Linear Collider Beam-Based Alignment Algorithms at FACET

linac, alignment, emittance, optics

1879

A. Latina, J. Pfingstner, D. Schulte
CERN, Geneva, Switzerland
E. Adli
University of Oslo, Oslo, Norway

The performance of future linear colliders will depend critically on beam-based alignment (BBA) and feedback systems, which will play a crucial role both in the linear and in the non-linear systems of such machines, e.g., the linac and the final-focus. Due to its characteristics, FACET is an ideal test-bench for BBA algorithms and linear collider beam-dynamics in general. We present the results of extensive computer simulations and their experimental verification.

TUPPR030

Thermo-mechanical Analysis of the CLIC Post-Linac Energy Collimators

linac, injection, collimation, betatron

1882

J. Resta-López
IFIC, Valencia, Spain
J.L. Fernández-Hernando
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
A. Latina
CERN, Geneva, Switzerland

Funding: FPA2010-21456-C02-01
The post-linac energy collimation system of the Compact Linear Collider (CLIC) has been designed for passive protection of the Beam Delivery System (BDS) against mis-steered beams due to failure modes in the main linac. In this paper, a thermo-mechanical analysis of the CLIC energy collimators is presented. This study is based on simulations using the codes FLUKA and ANSYS when an entire bunch train hit the collimators. Different failure mode scenarios in the main linac are considered. Moreover, we discuss the results for different collimator materials. The aim is to improve the collimator design in order to make a reliable and robust design so that it survives without damage from the impact of a full bunch train in case of likely events generating energy errors.

TUPPR033

Improved Modelling of the Thermo-mechanical Behavior of the CLIC Two-Beam Module

vacuum, RF-structure, linac, alignment

1891

G. Riddone, T.O. Niinikoski, F. Rossi
CERN, Geneva, Switzerland
R.J. Raatikainen, K. Österberg
HIP, University of Helsinki, Finland
A. Samoshkin
JINR, Dubna, Moscow Region, Russia

The luminosity goal of the CLIC collider, currently under study, imposes micrometer mechanical stability of the 2-m-long two-beam modules, the shortest repetitive elements of the main linacs. These modules will be exposed to variable high power dissipation during operation resulting in mechanical distortions in and between module components. The stability of the CLIC module is being tested in laboratory conditions at CERN in a full-scale prototype module. In this paper, the revised finite element model developed for the CLIC two-beam module is described. In the current model, the structural behavior of the module is studied in more detail compared to the earlier configurations, in particular for what regards the contact modeling. The thermal and structural results for the module are presented considering the thermo-mechanical behavior of the CLIC collider in its primary operation modes. These results will be compared to the laboratory measurements to be done in 2012 with the full-scale prototype module. The experimental results will allow for better understanding of the module behavior and they will be propagated back to the present thermo-mechanical model.

TUPPR037

Simulations of Higher Order Modes in the ACC39 Module of FLASH

cavity, HOM, dipole, higher-order-mode

1900

I.R.R. Shinton, R.M. Jones, P. Zhang
UMAN, Manchester, United Kingdom
Z. Li
SLAC, Menlo Park, California, USA

This study is primarily focused on the dipole component of the multiband expansion of the wakefield, with the emphasis being on the development of a HOM-based BPM system for ACC39 currently installed and in operation at FLASH and due to be installed at XFEL . Coupled inter-cavity modes are simulated together with a limited band of trapped modes. A suite of finite element computer codes (including HFSS and ACE3P) and globalised scattering matrix calculations (GSM) are used to investigate the modes in these cavities. In this way the nature of the multi-cavity nature of these modules is investigated with implications for a HOM-based BPM system and direct comparison to experimental results.

TUPPR039

Beam Dynamics Studies for the CLIC Main Linac

wakefield, linac, damping, emittance

1903

I. Nesmiyan, R.M. Jones
UMAN, Manchester, United Kingdom
A. Latina, D. Schulte
CERN, Geneva, Switzerland

Implications of the long-range wakefield on beam quality are investigated through a detailed beam dynamics study. Injection offsets are considered and the resulting emittance dilution recorded, including systematic and random sources of error. These simulations have been conducted for damped and detuned structures (DDS) and for waveguide damped structures–both for the CLIC collider.

TUPPR047

Vibration Model Validation for Linear Collider Detector Platforms

luminosity, damping, ground-motion, coupling

1921

K.J. Bertsche, J.W. Amann, T.W. Markiewicz, M. Oriunno, A.W. Weidemann, G.R. White
SLAC, Menlo Park, California, USA

Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
The ILC and CLIC reference designs incorporate reinforced-concrete platforms underneath the detectors so that the two detectors can each be moved onto and off of the beamline in a Push-Pull configuration. These platforms could potentially amplify ground vibrations which would reduce luminosity. In this paper we compare vibration models to experimental data on reinforced concrete structures, estimate the impact on luminosity, and summarize implications for the design of a reinforced concrete platform for the ILC or CLIC detectors.

TUPPR049

An X-band Standing Wave Dielectric Loaded Accelerating Structure

multipactoring, cavity, coupling, resonance

1927

C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
S.H. Gold
NRL, Washington, DC, USA
S. Kazakov
Fermilab, Batavia, USA
R. Konecny
ANL, Argonne, USA

Funding: DOE SBIR Phase I grant #DE-SC0006303
An 11.4 GHz standing wave dielectric loaded accelerating structure was recently developed. We expect to achieve a 120 MV/m gradient powered by a 10 MW 200 ns rf pulse from the X-band Magnicon at the Naval Research Laboratory. The structure uses on-axis rf coupling, which helps to localize the maximum EM fields within the dielectric region. Bench testing shows excellent agreement with the simulation results. The high power rf test is scheduled for January 2012.

TUPPR050

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

cavity, coupling, electron, 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.

TUPPR052

3D FEA Computation of the CLIC Machine Detector Interface Magnets

solenoid, quadrupole, shielding, luminosity

1936

A. Bartalesi, M. Modena
CERN, Geneva, Switzerland

A critical aspect of the Compact Linear Collider (CLIC) design is represented by the Accelerator/Experiment interface (called Machine Detector Interface or MDI). In the 3 TeV CLIC layout, the final focus QD0 quadrupole will be located inside the end-cap of the detector itself. This complex MDI scenario required to be simulated with a full 3D-FE analysis. This study was critical to check and control the magnetic cross-talk between the Detector Solenoid and the final Focus QD0 magnet and therefore to optimize the design of an “antisolenoids” system needed to shield the QD0 and the e⁻/e⁺ beams from the detector magnetic field. In this paper the development and evolution of the computational FE model is presented together with the results obtained and their implication on the CLIC MDI Design.

TUPPR053

Conceptual Design of the Linac4 Main Dump

linac, proton, radiation, booster

1939

I.V. Leitao, C. Maglioni, A. Sarrió Martínez
CERN, Geneva, Switzerland

Linac4 is the new CERN linear accelerator intended to replace the aging Linac2 as the injector to the Proton Synchrotron Booster (PSB) for increasing the luminosity of the Large Hadrons Collider (LHC). By delivering a 160MeV H⁻ beam, Linac4 will provide the necessary conditions to double the brightness and intensity of the beam extracted from the PSB. This paper describes the conceptual design of the Linac4 Main Dump, where two different concepts relying respectively on water and air cooling were compared and evaluated. Based on the application of analytical models for the energy deposited by the beam, heat conduction and cooling concepts, a parametric study was performed. This approach allowed the identification of the “optimal” configuration for these two conceptual geometries and their relative comparison. Besides giving the theoretical guidelines for the design of the new dump, this work also contributes to the development of analytical tools to allow a better understanding of the influence of the several design parameters in this type of low-energy beam intercepting devices.

TUPPR064

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

vacuum, electron, photon, 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, damping, electron

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.

TUPPR077

Simulation Studies for the LHC Long-Range Beam-Beam Compensators

optics, resonance, collider, betatron

2002

T.L. Rijoff, R.J. Steinhagen, F. Zimmermann
CERN, Geneva, Switzerland

The LHC performance and the minimum crossing angle are limited by long-range beam-beam collisions. Wire compensators can mitigate part of the long-range effects and may allow for smaller crossing angles, smaller β^*, or higher beam intensity. A prototype long-range wire compensator should be installed in the LHC by 2014/15. We report simulation studies examining and comparing the efficiency of the wire compensation, in terms of tune footprint or dynamic aperture, at various candidate locations, with different wire shapes, and for varying transverse distance from the beam.

TUPPR084

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

cavity, HOM, damping, electron

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.

TUPPR091

Status of the 160 MeV H⁻ Injection into the CERN PSB

injection, emittance, vacuum, proton

2041

W.J.M. Weterings, B. Balhan, E. Benedetto, J. Borburgh, C. Bracco, C. Carli, B. Goddard, K. Hanke, B. Mikulec, A. Newborough, R. Noulibos, J. Tan
CERN, Geneva, Switzerland

The 160 MeV H⁻ beam from the LINAC4 will be injected into the 4 superimposed rings of the PS Booster (PSB) with an new H⁻ charge-exchange injection system. This entails a massive upgrade of the injection region. The hardware requirements and constraints, the performance specifications and the design of the H⁻ injection region are described.

TUPPR097

Modeling and Simulation of LHC Beam-Based Collimator Setup

alignment, beam-losses, emittance, collider

2059

G. Valentino, N.J. Sammut
University of Malta, Information and Communication Technology, Msida, Malta
R.W. Assmann, F. Burkart, S. Redaelli, A. Rossi, D. Wollmann
CERN, Geneva, Switzerland
L. Lari
IFIC, Valencia, Spain

In the 2011 Large Hadron Collider run, collimators were aligned for proton and heavy ion beams using a semi-automatic setup algorithm. The algorithm provided a reduction in the beam time required for setup, an elimination of beam dumps during setup and higher accuracy with respect to manual alignment. A collimator setup simulator was developed based on a Gaussian model of the beam distribution as well as a parametric model of the beam losses. A time-varying beam loss signal can be simulated for a given collimator movement into the beam. The simulation results and comparison to measurement data obtained during collimator setups and dedicated fills for beam halo scraping are presented. The simulator will then be used to develop a fully automatic collimator alignment algorithm.

WEYA02

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

electron, 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]

WEOAA02

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

electron, diagnostics, radiation, 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]

WEEPPB001

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

electron, wakefield, laser, acceleration

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.

WEEPPB003

Modeling of 10 GeV-1 TeV Laser-Plasma Accelerators Using Lorentz Boosted Simulations

laser, plasma, acceleration, controls

2172

J.-L. Vay, E. Esarey, C.G.R. Geddes, W. Leemans, C.B. Schroeder
LBNL, Berkeley, California, USA
E. Cormier-Michel
Tech-X, Boulder, Colorado, USA
D.P. Grote
LLNL, Livermore, California, USA

Funding: Supported by US-DOE Contracts DE-AC02-05CH11231 and DE-AC52-07NA27344, US-LHC program LARP, and US-DOE SciDAC program ComPASS.
Modeling of laser-plasma wakefield accelerators in an optimal frame of reference [J.-L. Vay, Phys. Rev. Lett. 98 130405 (2007)] allows direct and efficient full-scale modeling of deeply depleted and beam loaded laser-plasma stages of 10 GeV-1 TeV (parameters not computationally accessible otherwise). This verifies the scaling of plasma accelerators to very high energies and accurately models the laser evolution and the accelerated electron beam transverse dynamics and energy spread. Over 4, 5 and 6 orders of magnitude speedup is achieved for the modeling of 10 GeV, 100 GeV and 1 TeV class stages, respectively. Agreement at the percentage level is demonstrated between simulations using different frames of reference for a 0.1 GeV class stage. Obtaining these speedups and levels of accuracy was permitted by solutions for handling data input (in particular particle and laser beams injection) and output in a relativistically boosted frame of reference, as well as mitigation of a high-frequency instability that otherwise limits effectiveness.
Used resources of NERSC, supported by US-DOE Contract DE-AC02-05CH11231.

WEEPPB011

Analysis of High Field Non-Linear Losses on SRF Surfaces Due to Specific Topographic Roughness

superconductivity, niobium, SRF, feedback

2188

C. Xu
The College of William and Mary, Williamsburg, USA
M.J. Kelley, C.E. Reece, C. Xu
JLAB, Newport News, Virginia, USA

Funding: This work is authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The high-field performance of SRF cavities will eventually be limited by the realization of fundamental material limits, whether it be Hc1 or Hsh, or some derivative thereof, at which the superconductivity is lost. Before reaching this fundamental field limit at the macro level, it must be encountered at localized, perhaps microscopic, sites of field enhancement due to local topography. If such sites are small enough, they may produce thermally stabilized normal-conducting regions which contribute non-linear losses when viewed from the macro resonant field perspective, and thus produce degradation in Q0. We have undertaken a calculation of local surface magnetic field enhancement from specific fine topographic structure by conformal mapping method and numerically. A solution of the resulting normal conducting volume has been derived and the corresponding RF ohmic loss simulated.

WEPPC008

FNAL Project X Conical Half-Wave Resonator Design

cavity, cryomodule, resonance, proton

2221

E.N. Zaplatin
FZJ, Jülich, Germany
A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA

Funding: This work is supported by the DOE SBIR Program, contract # DE-SC0006302.
A high-intensity proton accelerator complex proposed at Fermi National Accelerator Laboratory (Project X) should provide beam for a variety of physics projects. The superconducting resonators of different types will be used as accelerating structures. Here we describe the design of conical Half-Wave Resonator that is considered as an option for a first accelerating cavity for β=v/c=0.11 with the resonance frequency 162.5 MHz. A careful study of the fields in the cavity has been carried out in order to optimize the electromagnetic parameters of the structure (peak fields, quality factor, dissipation power). An intensive investigations were provided of the liquid helium vessel design to minimize cavity frequency shifts from the external loads. Different tuning schemes have been studied to secure a frequency tuning range to cope with fabrication tolerances. The paper reports results of numerical simulations of the cavity shape optimization and structural analyses. The detailed developments of the structure using numerical coupled analyses allowed to minimize the level of expected microphonics in cavity.

WEPPC018

Design of a Spoke Cavity for RIKEN RI-beam Factory

cavity, vacuum, ion, heavy-ion

2245

L. Lu
RIKEN, Saitama, Japan
O. Kamigaito, N. Sakamoto, K. Suda, K. Yamada
RIKEN Nishina Center, Wako, Japan

Designs of a CW superconducting rebuncher tri-spoke cavity for uranium beams with β = 0.303 has been studied. The estimated peak voltage is rather high as 3 mega-voltages (MV). The resonator frequency was chose as 219MHz which is 12 times of the foundational frequency. The buncher would be settled in a location between two booster cyclotrons (RRC: K = 540MeV, fRC: K = 570 MeV). In this cavity design, a flat E field distribution on beam axis was designed based on the Microwave Studio (MWS) simulations. The cavity parameters, detail designs and some simulated results will be reported in this paper.

WEPPC030

Second Sound Measurement Using SMD Resistors to Simulate Quench Locations on the 704 MHz Single-cell Cavity at CERN

cavity, cryogenics, linac, quadrupole

2269

K.C. Liao, O. Brunner, E. Ciapala, T. Junginger, W. Weingarten
CERN, Geneva, Switzerland

Oscillating superleak transducers (OSTs) containing a flexible porous membrane are widely used to detect the so-called second sound temperature wave when a quench event occurs in a superconducting RF cavity. In principle, from the measured speed of this wave and the travel time between the quench event and several OSTs, the location of the quench sites can be derived by triangulation. Second sound behavior has been simulated though different surface mount (SMD) resistors setups on a Superconducting Proton Linac (SPL) test cavity, to help understand the underlying physics and improve quench localisation. Experiments are described that have been conducted to search for explanation of heat transfer mechanism during cavity quench that causes contradictory triangulation results.

Poster WEPPC030 [1.473 MB]

WEPPC032

Analysis of the Four Rod Crab Cavity for HL-LHC

cavity, multipactoring, niobium, luminosity

2275

B.D.S. Hall, P.K. Ambattu, G. Burt, D. Doherty, C. Lingwood
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
P. Goudket
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The Hi-Lumi Upgrade to the LHC will utilise crab cavities to increase the peak luminosity and provide luminosity levelling at the increased crossing angle. A transversely compact design is required to fit within the limited space between opposing beamlines. In this paper a four rod TEM deflecting cavity (4RCC) is shown to be suitable for LHC. The variation of the deflecting voltage with radial offset has been minimised by careful design and an aluminium prototype has been constructed and beadpull measurements are compared to simulations. Multipacting simulations have been performed on the cavity geometry and it is predicted that the growth rate is less than unity for a clean surface. Pressure variations in the LHe can result in deformation of the complex shape which will alter the resonant frequency. Mechanical simulations have also been performed to assess the sensitivity of the frequency to pressure. In order to reduce the impact of these cavities on the LHC beam low impedance is required for the HOMs as well as the fundamental monopole mode. The couplers for the 4RCC cavity have been optimised to provide effective damping of these modes while rejecting the operating mode.

WEPPC035

Design and Construction of a High-Power RF Coupler for PXIE

cryomodule, vacuum, cavity, linac

2284

M.P. Kelly, Z.A. Conway, M. Kedzie, S.V. Kutsaev, P.N. Ostroumov
ANL, Argonne, USA
S. Nagaitsev
Fermilab, Batavia, USA

A power coupler has been designed and built at Argonne National Laboratory for use with the Project X Injector Experiment (PXIE) 162.5 MHz superconducting (SC) half-wave cavities. The 50 Ω coaxial capacitive coupler will be required to operate CW with up to 10 kW of forward power under any condition for the reflected power. A key feature is a moveable copper plated stainless steel bellows which will permit up to 3 cm of axial stroke and adjustment of Qext by roughly one order of magnitude in the range of 10^-5 to 10^-6. The mechanical and vacuum design will include two ceramic windows, one operating at room temperature and another at 70 Kelvin. The two window design allows the portion of the coupler assembled to the SC cavity in the clean room to be compact and readily cleanable. We present other design features including thermal intercepts to provide a large margin for RF heating and a mechanical guide assembly to operate cold and under vacuum with high reliability.

WEPPC036

Electromagnetic Design of 15 kW CW RF Input Coupler

cavity, cryomodule, linac, vacuum

2286

S.V. Kutsaev, M.P. Kelly, P.N. Ostroumov
ANL, Argonne, USA

Funding: This work was supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC02-06CH11357.
A new power coupler is under development at Argonne National Laboratory for a cw 40 MeV proton/deuteron linac for the SARAF project in Israel. This linac requires one 15 kW RF input power per superconducting cavity. Two different cavity options are still under consideration: 10⁹ MHz quarter-waves and 176 MHz half-waves. A coaxial capacitive input coupler has been designed and analyzed for these purposes. This paper presents the results of 3D electromagnetic simulations of this coupler together with the cavities mentioned above. An analysis of multipacting in the couplers is also presented.

WEPPC038

Status of the Short-Pulse X-ray Project at the Advanced Photon Source

cavity, LLRF, cryomodule, HOM

2292

A. Nassiri, N.D. Arnold, T.G. Berenc, M. Borland, B. Brajuskovic, D.J. Bromberek, J. Carwardine, G. Decker, L. Emery, J.D. Fuerst, A.E. Grelick, D. Horan, J. Kaluzny, F. Lenkszus, R.M. Lill, J. Liu, H. Ma, V. Sajaev, T.L. Smith, B.K. Stillwell, G.J. Waldschmidt, G. Wu, B.X. Yang, Y. Yang, A. Zholents
ANL, Argonne, USA
J.M. Byrd, L.R. Doolittle, G. Huang
LBNL, Berkeley, California, USA
G. Cheng, G. Ciovati, P. Dhakal, G.V. Eremeev, J.J. Feingold, R.L. Geng, J. Henry, P. Kneisel, K. Macha, J.D. Mammosser, J. Matalevich, A.D. Palczewski, R.A. Rimmer, H. Wang, K.M. Wilson, M. Wiseman
JLAB, Newport News, Virginia, USA
Z. Li, L. Xiao
SLAC, Menlo Park, California, 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.
The Advanced Photon Source Upgrade (APS-U) Project at Argonne will include generation of short-pulse x-rays based on Zholents’* deflecting cavity scheme. We have chosen superconducting (SC) cavities in order to have a continuous train of crabbed bunches and flexibility of operating modes. In collaboration with Jefferson Laboratory, we are prototyping and testing a number of single-cell deflecting cavities and associated auxiliary systems with promising initial results. In collaboration with Lawrence Berkeley National Laboratory, we are working to develop state-of-the-art timing, synchronization, and differential rf phase stability systems that are required for SPX. Collaboration with Advanced Computations Department at Stanford Linear Accelerator Center is looking into simulations of complex, multi-cavity geometries with lower- and higher-order modes waveguide dampers using ACE3P. This contribution provides the current R&D status of the SPX project.
* A. Zholents et al., NIM A 425, 385 (1999).

WEPPC043

Transverse Kick Analysis of SSR1 Due to Possible Geometrical Variations in Fabrication

cavity, linac, alignment, solenoid

2306

M.H. Awida, P. Berrutti, I.V. Gonin, T.N. Khabiboulline, V.P. Yakovlev
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC, under Contract DE-AC02-07CH11359 with the U.S. DOE
Due to fabrication tolerance, it is expected that some geometrical variations could happen to the SSR1 cavities of Project X, like small shifts in the transverse direction of the beam pipe or the spoke. It is necessary to evaluate the resultant transverse kick due to these geometrical variations, in order to make sure that they are within the limits of the correctors in the solenoids. In this paper, we report the transverse kick values for various fabrications errors and the sensitivity of the beam to these errors.

WEPPC051

Multipactor Simulation in SC Elliptical Shape Cavities

cavity, electron, 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.

WEPPC056

Pressure Sensitivity Characterization of Superconducting Spoke Cavities

cavity, linac, resonance, electromagnetic-fields

2339

D. Passarelli, M.H. Awida, I.V. Gonin, L. Ristori, V.P. Yakovlev
Fermilab, Batavia, USA

The following proposal illustrates a method to characterize the pressure sensitivity behavior of superconducting spoke cavities. This methodology relies on evaluating the variation of resonant frequency of a cavity by observing only the displacements at designed regions of the cavity. The proposed method permits a reduced computational burden and a systematic approach to achieve a minimum value of pressure sensitivity in a complex system of dressed cavity. This method has been used to characterize the superconducting spoke cavities typs⁻¹ (SSR1), under development for Project X, and to design the helium containment vessel in such way to reduce the pressure sensitivity value to zero.

WEPPC059

A Two-stage Injection-locked Magnetron for Accelerators with Superconducting Cavities

linac, injection, cavity, controls

2348

G.M. Kazakevich, G. Flanagan, R.P. Johnson, F. Marhauser, M.L. Neubauer
Muons, Inc, Batavia, USA
B. Chase, S. Nagaitsev, R.J. Pasquinelli, N. Solyak, V. Tupikov, D. Wolff, V.P. Yakovlev
Fermilab, Batavia, USA

Funding: Supported in part by SBIR Grant 4743 11SC06261
A concept for a two-stage injection-locked CW magnetron intended to drive Superconducting Cavities (SC) for intensity-frontier accelerators has been proposed. The concept is based on a theoretical model that considers a magnetron as a forced oscillator; the model has been experimentally verified with a 2.5 MW pulsed magnetron. The two-stage CW magnetron can be used as a RF power source for Fermilab’s Project-X to feed separately each of the SC of the 8 GeV pulsed linac. For Project-X the 1.3 GHz two-stage magnetron with output power of 20-25 kW and expected output/input power ratio of about 35-40 dB would operate in a quasi-CW mode with a pulse duration ≤ 10 ms and repetition rate of 10 Hz. The magnetrons for both stages should be based on the commercial prototypes to decrease the cost of the system. An experimental model of the two-stage CW S-band magnetron with peak power of 1 kW, with pulse duration of 1-10 ms, has been developed and built for study. A description of the theoretical and experimental models, simulations, and experimental results are presented and discussed in this work.

WEPPC068

Multipacting Simulation and Analysis for the FRIB β = 0.085 Quarter Wave Resonators using Track3P

cavity, resonance, linac, niobium

2366

L. Ge, C. Ko, Z. Li
SLAC, Menlo Park, California, USA
J. Popielarski
FRIB, East Lansing, Michigan, USA

Funding: Work supported by DOE Office of Science under Cooperative Agreement DE- SC0000661, DOE Contract No. DE-AC02-76SF00515, and used resources of NERSC supported by DOE Contract No. DE-AC02- 05CH11231.
The drive linac for the Facility for Rare Isotope Beams (FRIB) utilizes several types of low beta superconducting resonators to accelerate the ion beams from 0.3 MeV per nucleon to 200 MeV per nucleon. Multipacting is an issue of concern for such superconducting resonators as they have unconventional shapes. We have used the parallel codes Tack3P and Omega3P, developed at SLAC under the support of the DOE SciDAC program, to analyze the multipacting barriers of such resonators. In this paper, we will present the simulation results for the β(v/c) = 0.085 Quarter Wave Resonator (QWR) for the FRIB project. Experimental data will also be presented to benchmark with the simulation results.

WEPPC074

HOM Studies on the Cornell ERL Prototype Cavity in a Horizontal Test Cryomodule

cavity, HOM, higher-order-mode, linac

2384

N.R.A. Valles, M.G. Billing, G.H. Hoffstaetter, M. Liepe, C.E. Mayes
CLASSE, Ithaca, New York, USA

The main linac 7-cell cavity for Cornell's Energy Recovery Linac was optimized to maximize threshold current through the ERL. This was achieved by designing center and end cells that reduce the strength of dipole higher-order modes. A prototype cavity was fabricated based on the optimized RF design and found to meet fundamental mode specifications in a vertical test. The higher-order-mode spectrum was measured when the cavity was installed in a horizontal test cryomodule and is compared to 2D and 3D EM simulations.

WEPPC079

Residual Resistance Studies at Cornell

cavity, SRF, linac, accelerating-gradient

2393

S. Posen, D. Gonnella, G.H. Hoffstaetter, M. Liepe
CLASSE, Ithaca, New York, USA
J. Oh
Cornell University, Ithaca, New York, USA

The Cornell single-cell temperature mapping system has been adapted for use with ILC and Cornell ERL-shape superconducting accelerator cavities. The system was optimized for low-noise, high-precision measurements with the goal of measuring resistances as low as 1 nohms. Using this system, a T-map of an ILC single cell was obtained at accelerating fields below the onset of Q-slope and at temperatures at which BCS resistance is small, producing a measurement of the distribution of residual resistance over the surface of the cavity. Standard procedures were used in preparing the cavity to avoid Q-disease and trapped flux caused by cooling the cavity through its transition in the presence of magnetic fields. Studying the T-map gives clues to the source of residual resistance, so that steps can be taken to reduce it, thereby lowering losses and increasing Q0. The temperature map noise-reduction studies as well as the residual resistance results are presented in this paper.

WEPPC080

Minimizing Helium Pressure Sensitivity in Elliptical SRF Cavities

cavity, linac, factory, beam-loading

2396

S. Posen, M. Liepe
CLASSE, Ithaca, New York, USA

Superconducting cavities in CW operation with small beam loading can operate at high QL to significantly reduce power requirements. However, the resulting small bandwidth makes them vulnerable to microphonics from helium pressure fluctuations, which can detune the cavity and cause it to trip. In this paper, we present a mechanical optimization of elliptical cavities for minimization of df/dp, the sensitivity to helium pressure changes. Using the Cornell ERL main linac cavity as an example, an analytical model is developed to illustrate the factors that contribute to df/dp. Methods to reduce df/dp are presented. In addition, df/dp measurements made at the Cornell Horizontal Test Cryostat are presented and corrections to the model are made to account for the thickness of the welds in the helium vessel.

WEPPC081

Measurement of the Mechanical Properties of Superconducting Cavities During Operation

cavity, resonance, linac, feedback

2399

S. Posen, M. Liepe
CLASSE, Ithaca, New York, USA

The Horizontal Test Cryostat (HTC) contains the first prototype 7-cell 1.3 GHz superconducting cavity for the Cornell ERL main linac. In this paper, experimental measurements of the cavity's mechanical properties are presented. The mechanical resonances were studied using a Dynamic Signal Analyzer, which measured the transfer function from the fast piezo tuner to itself and the cavity frequency. The microphonics detuning of the cavity was measured, and found to satisfy the specification that the maximum detuning be below 20 Hz, even without feedback from the piezos. Correlations were studied between the microphonics detuning and the helium pressure, piezo sense signal, and the ground vibrations. The Lorentz force detuning (LFD) coefficient was also measured. The frequencies of the mechanical resonances were compared to simulation. In addition, the performance of the frequency tuners was evaluated. Both the mechanical tuner and the piezo were found to be highly linear with very little hysteresis even on small scales.

WEPPC087

Second Harmonic Cavity Design for Project-X Main Injector

cavity, dipole, HOM, impedance

2417

L. Xiao, C.-K. Ng
SLAC, Menlo Park, California, USA
J.E. Dey, I. Kourbanis
Fermilab, Batavia, USA

In order to accelerate the proposed beam intensity for Project-X, a new RF system for Main Injector (MI) will be required. A new 53 MHz first harmonic RF cavity that meets the MI requirements for Project-X has been designed. In order to reduce the peak longitudinal beam density a 10⁶ MHz second harmonic RF system is also needed. The first harmonic RF cavity design is a quarter wave coaxial resonator with a single accelerating gap and a perpendicular biased ferrite tuner. The second harmonic RF cavity baseline design is similar to the fundamental one and scaled down from it. RF simulations and shape optimizations on the second harmonic cavity are carried out to obtain the optimal performance which meets Project-X requirements. The results are discussed and presented in this paper.

WEPPC110

3D Simulations of Multipacting in the 56 MHz SRF Cavity

cavity, HOM, electron, 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.

WEPPC111

Multipacting Simulation ADN Test Results of BNL 704 MHz SRF Gun

cavity, cathode, gun, SRF

2480

W. Xu, S.A. Belomestnykh, I. Ben-Zvi, C. Cullen, H. Hahn, X. Liang, G.T. McIntyre, D. Pate, S.P. Pontieri, C. Schultheiss, T. Seda, T.N. Tallerico, R. Than, R.J. Todd, S.J. Tuozzolo, A. Zaltsman
BNL, Upton, Long Island, New York, USA
J. Dai
SBU, Stony Brook, New York, USA
L.R. Hammons
Stony Brook University, Stony Brook, USA

Funding: This work was supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
The BNL 704 MHz SRF gun has a grooved choke joint to support the photo-cathode. Due to the distortion of grooves at the choke joint during the BCP for the choke joint, several multipacting barriers showed up when it was tested with Nb cathode stalk at JLab. We built a setup to use the spare large grain SRF cavity to test and condition the multipacting at BNL with various power sources. The test is carried out with three steps: cavity, cavity with Nb cathode stalk, and cavity with copper cathode stalk. This paper summarizes the results of multipacting simulation, and presents large grain cavity test setup and the test results.

WEPPC112

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

cavity, collider, linac, electron

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.

WEPPC114

Design, Simulation and Conditioning of the Fundamental Power Couplers for BNL SRF Gun

vacuum, gun, SRF, klystron

2489

W. Xu, Z. Altinbas, S.A. Belomestnykh, I. Ben-Zvi, S. Deonarine, D.M. Gassner, J.P. Jamilkowski, P. Kankiya, D. Kayran, N. Laloudakis, L. Masi, G.T. McIntyre, D. Pate, D. Phillips, T. Seda, A.N. Steszyn, T.N. Tallerico, R.J. Todd, D. Weiss, A. Zaltsman
BNL, Upton, Long Island, New York, USA
M.D. Cole, G.J. Whitbeck
AES, Medford, NY, USA

Funding: This work was supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE.
The 704 MHz SRF gun for the BNL Energy Recovery Linac (ERL) prototype uses two fundamental power couplers (FPCs) to deliver up to total 1 MW of CW RF power into the half-cell cavity. To prepare the couplers for high-power RF service and process multipacting, the FPCs should be conditioned prior to installation into the gun cryomodule. A room-temperature test stand was configured for conditioning FPCs in full reflection regime with varied phase of the reflecting wave. The FPCs have been conditioned up to 250 kW in pulse mode and 125 kW in CW mode. The multipacting simulations were carried out with Track3P code developed at SLAC. The simulations matched the experimental results very well. This paper presents the FPC RF and thermal design, multipacting simulations and conditioning of the BNL gun FPCs.

WEPPD003

Development of a Condenser for the Helium Phase Separator at NSRRC

vacuum, cryogenics, synchrotron, synchrotron-radiation

2501

C.P. Liu, C.M. Cheng, F. Z. Hsiao, T.Y. Huang, H.H. Tsai
NSRRC, Hsinchu, Taiwan

A helium phase separator with a condenser is under fabrication and assembly at National Synchrotron Radiation Research Center (NSRRC). The objective of a helium phase separator with its condenser is to separate two-phase helium flow and to re-condense vaporized gaseous helium with a cryo-cooler of Gifford-McMahon type. This paper presents the design and fabrication of the condenser, a key component of the helium phase separator. A preliminary steady-state simulation of the efficiency of the helium condenser is also presented.
"Condenser","Rate of condensation"

WEPPD007

Integrated Thermal Analysis of the FRIB Cryomodule Design

cryomodule, cryogenics, vacuum, radiation

2510

Y. Xu, M. Barrios, F. Casagrande, M.J. Johnson, M. Leitner
FRIB, East Lansing, Michigan, USA
D. Arenius, V. Ganni, W.J. Schneider, M. Wiseman
JLAB, Newport News, Virginia, USA

Funding: This material is based upon work supported by the U.S. Department of Energy Office of Science under Cooperative Agreement DE-SC0000661
Thermal analysis of the FRIB cryomodule design is performed to determine the heat load to the cryogenic plant, to minimize the cryogenic plant load, to simulate thermal shield cool down as well as to determine the pressure relief sizes for failure conditions. Static and dynamic heat loads of the cryomodules are calculated and the optimal shield temperature is determined to minimize the cryogenic plant load. Integrated structural and thermal simulations of the 1100-O aluminium thermal shield are performed to determine the desired cool down rate to control the temperature profile on the thermal shield and to minimize thermal expansion displacements during the cool down. Pressure relief sizing calculations for the SRF helium containers, solenoids, helium distribution piping, and vacuum vessels are also described.
Michigan State University designs and establishes FRIB as a DOE Office of Science National User Facility in support of the mission of the Office of Nuclear Physics.

WEPPD011

Study of the Pressure Profile Inside the NEG Coated Chambers of the SIS 18

vacuum, dipole, quadrupole, ion

2519

M.C. Bellachioma, H. Kollmus, A. Krämer, J. Kurdal, H. Reich-Sprenger, L. Urban, M. Wengenroth
GSI, Darmstadt, Germany

In the context of the technical developments for the construction of FAIR at GSI, an intensive programme for the vacuum upgrade of the existing SIS 18 was started in 2005, with the aim to improve the beam lifetime and intensity. To reach these purposes also the installation of NEG coated dipole and quadrupole chambers is foreseen. During the upgrade shutdowns performed between 2006 and 2009 the vacuum chambers of approximately 65% of the SIS18 circumference were replaced by NEG coated pipes. To evaluate in detail the pressure profile inside the coated chambers mounted into the accelerator a dedicated experimental set-up, which reproduces a vacuum environment similar to the one of the SIS 18, was built. Using three gauges, mounted in different positions of a coated chamber, it was possible to measure the pressure in the range of 10^-12 mbar inside the activated NEG pipe and 10^-11 mbar outside the pipe at the pumping posts. Additionally, a modelling of a SIS18 vacuum sector was realised and the pressure variation values obtained by a Monte-Carlo simulation were compared with those measured. In this paper the experimental results and the vacuum simulations are described and discussed.

WEPPD015

Saturation Behaviour of the LHC NEG Coated Beam Pipes

vacuum, injection, site, insertion

2525

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

In the CERN Large Hadron Collider (LHC), about 6 km of the UHV beam pipe are at room temperature and serve as experimental or utility insertions. TiZrV non-evaporable getter (NEG) coating is used to maintain the design pressure during beam operation. Molecular desorption due to dynamic effects is stimulated during protons operation at high intensity. This phenomenon produces an important gas load from the vacuum chamber walls which could lead to a partial or total saturation of the NEG coating. To keep the design vacuum performances and to schedule technical interventions for NEG re-activation, it is necessary to take in account all these aspects and to regularly evaluate the saturation level of the NEG coating. Experimental studies in a typical LHC vacuum sector were conducted in order to identify the best method to assess the saturation level of the beam pipe. Partial saturation of the NEG was performed and the effects in the variations of pressure reading, effective pumping speed, transmission and capture probability are analysed. Finally, based on these results, a detailed analysis of the NEG coating saturation level of some area of the LHC is presented and analysed.

WEPPD017

Development of a New RF Finger Concept for Vacuum Beam Line Interconnections

vacuum, impedance, linac, higher-order-mode

2531

C. Garion, A. Lacroix, H. Rambeau
CERN, Geneva, Switzerland

RF contact fingers are primarily used as a transition element to absorb the thermal expansion of vacuum chambers during bake-out and also to compensate for mechanical tolerances. They have to carry the beam image current to avoid the generation of Higher Order Modes and to reduce beam impedances. They are usually made out of copper beryllium thin sheets and are therefore very fragile and critical components. In this paper, a robust design based on a deformable finger concept is proposed. It allows the compensation of large longitudinal movements and also defaults such as transverse offset, twist or bending. The concept of this new RF fingers is first explained, then the design of the component is presented. The mechanical study based on a highly non linear Finite Element model is shown as well as preliminary tests, including fatigue assessment, carried out on prototypes.

WEPPD027

Global and Local Loss Suppression in the UA9 Crystal Collimation Experiment

collimation, ion, proton, collider

2561

W. Scandale
LAL, Orsay, France
S. Montesano
CERN, Geneva, Switzerland

UA9 was operated in the CERN-SPS for some years in view of investigating the feasibility of the halo collimation assisted by bent crystals. Two-millimeter-long silicon crystals, with bending angles of about 150 mirrored, are used as primary collimators. The crystal collimation process is obtained consistently through channeling with high efficiency. The loss profiles in the area of the crystal-collimator setup and in the downstream dispersion suppressor area show a steady reduction of slightly less than one order of magnitude at the onset of the channeling process. This result holds both for protons and for lead-ions. The corresponding loss map in the accelerator ring is accordingly reduced. These observations strongly support our expectation that the coherent deflection of the beam halo by a bent crystal should enhance the collimation efficiency in hadron colliders, such as LHC.
for the UA9 Collaboration

WEPPD028

Collimators and Materials for High Intensity Heavy Ion Synchrotrons

ion, heavy-ion, proton, collimation

2564

J. Stadlmann, H. Kollmus, P.J. Spiller, I. Strašík, N.A. Tahir, M. Tomut, C. Trautmann
GSI, Darmstadt, Germany
L.H.J. Bozyk
TU Darmstadt, Darmstadt, Germany

Funding: Funded by EU FP7 WP8 ColMat and Federal Republic of Germany
The operation of high power high brightness accelerators requires huge efforts for beam cleaning and machine protection. Within the WP 8 (ColMat)of the EU research framework EuCARD we investigate new materials and methods for beam collimation and machine protection. TWe present an overview of these activities at the GSI Helmholtzzentrum für Schwerioneforschung in Darmstadt. Simulations of accidental beam losses in LHC and SIS100 have been performed. Scenarios for halo collimation of heavy ions and protons in SIS100 routine operation have been investigated. A prototype of a cryogenic collimator for charge exchange losses during intermediate charge state heavy ion operation in SIS100 has been build and tested with beam. Several candidates of advances composite materials for collimation system upgrades of present and construction of future high power accelerators have been irradiated and their properties are being characterized. Most deliverables and milestones of the R&D programm have already been reached before the end of the funding period. A summary of the obtained results will be presented.

WEPPD031

A Transverse Electron Target for Heavy Ion Storage Rings

electron, target, ion, interaction-region

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.

WEPPD052

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

undulator, electron, laser, 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

electron, laser, undulator, acceleration

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.

WEPPD062

Measurements of the First RF Prototype of the Spiral2 Single Bunch Selector

vacuum, impedance, high-voltage, scattering

2663

M. Di Giacomo
GANIL, Caen, France
A.C. Caruso, F. Consoli, G. Gallo, D. Rifuggiato, E. Zappalà
INFN/LNS, Catania, Italy
A. Longhitano
ALTEK, San Gregorio (CATANIA), Italy

Funding: Work supported by EU commission 7th framework project n. 212692.
The single bunch selector of the Spiral2 driver uses 100 Ω travelling wave electrodes driven by fast pulse generators. A 2.5 kV, 1 kW feed-through and a vacuum chamber housing the water cooled electrodes have been designed and built. The paper reviews the whole design and reports the results of first RF and power measurements.

WEPPD068

High Power Collinear Load Coated with FeSiAl

cavity, linac, resonance, factory

2678

L.G. Shen, X.L. Fu, Y. Sun, F. Zhang
USTC/PMPI, Hefei, Anhui, People's Republic of China
Y.J. Pei
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: This work is supported by the NSFC (NO. 10775128 and NO.51075381)
Aimed at substituting output coupler to absorb remnant power of the LINAC, collinear load coated with high loss materials is expected to come reality. FeSiAl load is studied. The effect of the coating volume upon the cavity frequency and Q factor is analyzed and the dimension compensations of the cavities are suggested to tune the load cavities at 2856 MHz. Orthogonal Experimental Method is utilized to investigate the sensitivity of permittivity (both real part and imaginary part) and permeability (both real part and imaginary part) to cavity characteristics. Five cavities with different coating dimensions are manufactured and their operating frequencies and Q are measured. Compared with the simulations, they show that the Q factor, which is characterization of the actual attenuation of the FeSiAl, agrees very well with the theoretical value and Q factor of the resonant cavity is measured with the probe method. The relationship between Q factor and the length of the test probe is deduced and eventually the individual Q value of a load cavity is extracted. Simulation shows the FeSiAl load can support average power over 15 kW and the one-way attenuation is about 30 dB.

WEPPD071

The FLUKA LineBuilder and Element DataBase: Tools for Building Complex Models of Accelerator Beam Lines

optics, injection, insertion, proton

2687

A. Mereghetti
UMAN, Manchester, United Kingdom
V. Boccone, F. Cerutti, R. Versaci, V. Vlachoudis
CERN, Geneva, Switzerland

Extended FLUKA models of accelerator beam lines can be extremely complex: heavy to manipulate, poorly versatile and prone to mismatched positioning. We developed a framework capable of creating the FLUKA model of an arbitrary portion of a given accelerator, starting from the optics configuration and a few other information provided by the user. The framework includes a builder (LineBuilder), an element database and a series of configuration and analysis scripts. The LineBuilder is a Python program aimed at dynamically assembling complex FLUKA models of accelerator beam lines: positions, magnetic fields and scorings are automatically set up, and geometry details such as apertures of collimators, tilting and misalignment of elements, beam pipes and tunnel geometries can be entered at user's will. The element database (FEDB) is a collection of detailed FLUKA geometry models of machine elements. This framework has been widely used for recent LHC and SPS beam-machine interaction studies at CERN, and led to a drastic reduction in the time otherwise required to rework old machine models, and to a coherent and traceable description of the inputs used for all the simulations.

WEPPD075

A Novel Planar Balun Structure for Continuous Wave 1 kW, 500 MHz Solid-state Amplifier Design

synchrotron, impedance, coupling, HOM

2699

T.-C. Yu, L.-H. Chang, M.H. Chang, L.J. Chen, F.-T. Chung, M.-C. Lin, Y.-H. Lin, C.H. Lo, M.H. Tsai, Ch. Wang, T.-T. Yang, M.-S. Yeh
NSRRC, Hsinchu, Taiwan

In general, the coaxial type balun plays key role in push-pull amplifier design in the increasing high power solid-state technique transmitter design for accelerator application. However, the coaxial baluns not only increase the complexity in manufacturing procedure but also introduce additional tolerance variation between modules. The variation between parallel power modules would decreases combining efficiency and thus increase the operation cost. Here, a novel planar balun has been proposed and successfully implemented on 1kW solid-state amplifier design for continuous operation with newly designed water cooling plates. The long-term CW test has demonstrated the feasibility of the newly designed planar is quite suitable for CW operation with its excellent low loss, balance property and also low tolerance between modules in mass production.

WEPPD077

Generation of Picosecond Electron-bunch Trains with Variable Spacing Using a Multi-pulse Photocathode Laser

laser, quadrupole, electron, wakefield

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.

WEPPD078

Progress with PXIE MEBT Chopper

kicker, vacuum, radio-frequency, coupling

2708

V.A. Lebedev, A.Z. Chen, R.J. Pasquinelli, D.W. Peterson, G.W. Saewert, A.V. Shemyakin, D. Sun, M. Wendt
Fermilab, Batavia, USA
T. Tang
SLAC, Menlo Park, California, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
A capability to provide a large variety of bunch patterns is crucial for the concept of the Project X serving MW-range beam to several experiments simultaneously. This capability will be realized by the Medium Energy Beam Transport’s (MEBT) chopping system that will divert 80% of all bunches of the initially 5mA, 2.1 MeV CW 162.5 MHz beam to an absorber according to a pre-programmed bunch-by-bunch selection. Being considered one of the most challenging components, the chopping system will be tested at the Project X Injector Experiment (PXIE) facility that will be built at Fermilab as a prototype of the Project X front end. The bunch deflection will be made by two identical sets of travelling-wave kickers working in sync. Presently, two versions of the kickers are being investigated: a helical 200 Ω structure with a switching-type 500 V driver and a planar 50 Ω structure with a linear ±250 V amplifier. This paper will describe the chopping system scheme and functional specifications for the kickers, present results of electromagnetic measurements of the models, discuss possible driver schemes, and show a conceptual mechanical design.

WEPPP004

A Reciprocity Principle for Wakefields in a Two-Channel Coaxial Dielectric Structure

wakefield, vacuum, acceleration, dipole

2726

G.V. Sotnikov
NSC/KIPT, Kharkov, Ukraine
J.L. Hirshfield, T.C. Marshall, G.V. Sotnikov
Omega-P, Inc., New Haven, USA
S.V. Shchelkunov
Yale University, Beam Physics Laboratory, New Haven, Connecticut, USA

Funding: Research is supported by U.S. Department of Energy, Office of High Energy Physics.
The reciprocity principle* is often used in applications of classical electromagnetism. We have employed this principle for testing wakefields set up by an electron bunch in a two-channel coaxial dielectric structure (CDWA)**. For numerical studies we take a ~1-THz fused silica structure which we plan to test at FACET/SLAC; it has dimensions: outer shell, OD=800 μm, ID=500 μm; inner shell OD=181 μm, ID=50 μm. The structure is energized by a 23-GeV, 3-nC bunch having axial RMS size=25 μm. FACET has no drive bunch of annular shape as required for a CDWA; nevertheless, our analytical studies and simulations prove that for the axial wakefield, an annular drive bunch can be replaced by a pencil-like bunch of the same charge traveling in the annular vacuum channel. The longitudinal electric field along the accelerator channel axis (as recorded by a witness bunch) set up by this pencil-like bunch is the same as in the conventional structure of the CDWA. Moreover, if we interchange the drive bunch and the witness bunch, the witness bunch will register the same axial wakefield. However, the stability of the annular bunch is far superior to that of the pencil bunch.
*L. D. Landau and E. M. Lifshitz, Electrodynamics of Continuous Media (Addison-Wesley: Reading, MA, 1960).
**G. Sotnikov et al., PRST-AB, 061302 (2009).

WEPPP005

Progress on Muon Parametric-resonance Ionization Cooling Channel Development

resonance, emittance, quadrupole, betatron

2729

V.S. Morozov, Y.S. Derbenev
JLAB, Newport News, Virginia, USA
A. Afanasev
GWU, Washington, USA
K.B. Beard, R.P. Johnson
Muons, Inc, Batavia, USA
B. Erdelyi, J.A. Maloney
Northern Illinois University, DeKalb, Illinois, USA

Funding: Supported in part by DOE SBIR grant DE-SC0005589. Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Parametric-resonance Ionization Cooling (PIC) is intended as the final 6D cooling stage of a high-luminosity muon collider. To implement PIC, a continuous-field twin-helix magnetic channel was developed. A 6D cooling with stochastic effects off is demonstrated in a GEANT4/G4beamline model of a system where wedge-shaped Be absorbers are placed at the appropriate dispersion points in the twin-helix channel and are followed by short rf cavities. To proceed to cooling simulations with stochastics on, compensation of the beam aberrations from one absorber to another is required. Initial results on aberration compensation using a set of various-order continuous multipole fields are presented. As another avenue to mitigate the aberration effect, we optimize the cooling channel’s period length. We observe a parasitic parametric resonance naturally occurring in the channel’s horizontal plane due to the periodic beam energy modulation caused by the absorbers and rf. We discuss options for compensating this resonance and/or properly combining it with the induced half-integer parametric resonance needed for PIC.
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.

WEPPP008

Vacuum Laser Acceleration Experiment Perspective at Brookhaven National Lab-Accelerator Test Facility

laser, electron, acceleration, vacuum

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

laser, electron, 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.

WEPPP014

Modeling of Quasi-phase Matching in an Aperiodic Corrugated Plasma Waveguide for High-efficiency Direct Laser Electron Acceleration

electron, plasma, laser, acceleration

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).

WEPPP016

De-neutralization of Laser Produced Proton Pulse in a Strong Solenoidal Magnetic Field

electron, proton, 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.

WEPPP026

Dielectric-plate-implanted Higher Order Mode (HOM) Waveguide for High Intensity Multi-beam Device Application

HOM, wakefield, lattice, electron

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.

WEPPP032

Inverse Free Electron Laser Acceleration Using Ultra-fast Solid State Laser Technology

laser, undulator, acceleration, electron

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.

WEPPP036

Undulator Commissioning for a High-Energy-Gain Inverse Free Electron Laser Experiment

undulator, laser, electron, 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, electron, 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, electron

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.

WEPPP045

Beam-breakup Analysis for an Annular Cherenkov High Gradient Wakefield Accelerator

wakefield, vacuum, electron, 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).

WEPPP046

Nonlinear Dielectric Wakefield Experiment for FACET

wakefield, controls, acceleration, factory

2825

P. Schoessow, S.P. Antipov, C.-J. Jing, A. Kanareykin
Euclid TechLabs, LLC, Solon, Ohio, USA
S. Baturin
LETI, Saint-Petersburg, Russia

Funding: Work supported by the SBIR Program, US Dept. of Energy.
Recent advances in ferroelectric ceramics have resulted in new possibilities for nonlinear devices for particle accelerator and rf applications. The new FACET (Facility for Advanced Accelerator Experimental Tests) at SLAC provides an opportunity to use the GV/m fields from its intense short pulse electron beams to perform experiments using the nonlinear properties of ferroelectrics. Simulations of Cherenkov radiation in the THz planar and cylindrical nonlinear structures to be used in FACET experiments will be presented. Signatures of nonlinearity are clearly present in the simulations: superlinear scaling of field strength with beam intensity, frequency upshift, and development of higher frequency spectral components.

WEPPP052

Self-modulation of Long Particle Bunches in Plasmas at SLAC

plasma, wakefield, electron, 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, focusing, electron

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).

WEPPP057

Orbit Correction Studies using Neural Networks

controls, storage-ring, target, synchrotron

2837

E. Meier, G. LeBlanc, Y.E. Tan
ASCo, Clayton, Victoria, Australia

This paper reports the use of Neural Networks for orbit correction at the Australian Synchrotron Storage Ring. The proposed system uses two Neural Networks in an actor-critic scheme to model a long term cost function and compute appropriate corrections. The system is entirely based on the history of the beam position and the actuators, the corrector magnets, in the storage ring. This makes the system auto-tuneable, which has the advantage of avoiding the use of a response matrix. As a generic and robust orbit correction program it can be used during commissioning and in slow orbit feedback. In this study, we present positive initial results of the simulations of the storage ring in Matlab. We will also discuss the possibility of reconstructing the response matrix from the information stored in the neural network for offline orbit response matrix analysis.

WEPPP066

Performance Simulations of a Phase Stabilization System Prototype for CTF3

feedback, kicker, collider, linac

2858

A. Gerbershagen, T. Persson, D. Schulte, P.K. Skowroński
CERN, Geneva, Switzerland
P. Burrows, G.B. Christian
Oxford University, Physics Department, Oxford, Oxon, United Kingdom
A. Gerbershagen, C. Perry
JAI, Oxford, United Kingdom
E. Ikarios
National Technical University of Athens, Athens, Greece

The CLIC drive beam provides RF power for acceleration of the main beam, and hence the drive beam’s longitudinal phase tolerances are very tight. A feedforward chicane consisting of four electromagnetic kickers is proposed as a correction system for the phase errors, which should allow loosening of the tolerances. A prototype of such a chicane system, developed by CERN, INFN and the University of Oxford, is planned to be installed at CFT3 in 2012. The present paper summarizes the parameters of the planned phase correction system and presents simulations, which are used to make predictions of the performance of such a feedforward system at CTF3.

WEPPP070

Simulation of the APS Storage Ring Orbit Real-Time Feedback System Upgrade Using MATLAB

feedback, storage-ring, controls, dipole

2870

S. Xu, G. Decker, R.I. Farnsworth, F. Lenkszus, H. Shang, X. Sun
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.
The Advanced Photon Source (APS) storage ring orbit real-time feedback (RTFB) system plays an important role in stabilizing the orbit of the stored beam. An upgrade is planned that will improve beam stability by increasing the correction bandwidth to 200 Hz or higher. To achieve this, the number of available steering correctors and beam position monitors (BPMs) will be increased, and the sample rate will be increased by an order of magnitude. An additional benefit will be the replacement of aging components. Simulations have been performed to quantify the effects of different system configurations on performance.

WEPPP071

Phase Noise Studies at the Advanced Photon Source

storage-ring, synchrotron, feedback, photon

2873

N. Sereno, G. Decker, R.M. Lill, B.X. Yang
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.
Phase noise generated primarily by power line harmonics modulating the 352-MHz rf system in the APS storage ring is a dominant source of high- frequency beam motion, both longitudinally and transversely, due to dispersion in the lattice. It also places fundamental limits on the ability to generate picosecond-scale x-ray pulses for fast pump / probe experiments*. Measurements using turn-by-turn beam position monitors (BPMs) located at high-dispersion locations are compared and contrasted with results from a dedicated S-band phase detector connected to either a capacitive pickup electrode or a diamond x-ray detector. Horizontal beam position at high-dispersion locations is related directly to beam phase by a very simple relation involving the momentum compaction. Simulation results are used to validate this relationship and to quantify the relation between phase noise on the main rf vs beam arrival time jitter.
* A. Zholents et al., NIM A 425, 385 (1999).

WEPPP074

Study of a Wideband Feedback Kicker for the SPS

kicker, impedance, feedback, cavity

2882

S. De Santis, Z. Paret, A. Ratti
LBNL, Berkeley, California, USA
A. Gallo, F. Marcellini
INFN/LNF, Frascati (Roma), Italy

Funding: Work supported by the US Department of Energy under Contracts DE-AC02-05CH11231 and DE-AC02-76SF00515, and through the US LHC Accelerator Research Program (LARP).
The LHC luminosity upgrade currently being planned at CERN depends in large measure on a successful upgrade of its injectors chain. In particular the storing of higher currents in the SPS presents a significant challenge from the point of view of the beam stability. Electron cloud driven and transverse mode-coupled instabilities can disrupt the stored beam to the point of making injection in the LHC impossible. These types of instabilities are characterized by fast growth times and substantial spectral components at high frequency. Therefore a key aspect of any feedback system capable of effectively controlling the instability growth is the development of a suitable kicker with a high frequency response. In this paper we investigate the technologies available for such a kicker and identify a possible solution to be implemented on the SPS. By combining a lower frequency stripline kicker with a high frequency module, such as a damped cavity or a slotted waveguide, it would be possible to provide shunt impedances around 1000 Ω on a bandwidth from DC to 1 GHz. The basic parameters and limits of such a solution are discussed.

WEPPP076

Analysis of Numerical Noise in Particle-In-Cell Simulations of Single-Bunch Transverse Instabilities and Feedback in the CERN SPS

feedback, emittance, pick-up, kicker

2888

R. Secondo, J.-L. Vay, M. Venturini
LBNL, Berkeley, California, USA

Funding: Work supported by the US-DOE and the US-LHC Accelerator Research Program LARP under Contract DE-AC02-05CH11231. Used resources of NERSC and the Lawrencium cluster at LBNL
The operation at high current of the SPS at CERN is limited by transverse Single-Bunch instabilities generated by the effect of electron clouds. A model of a high bandwidth feedback control system has been implemented in the macro-particle code WARP to study bunch dynamics and identify system requirements for the efficient damping of single-bunch transverse instability. We analyze the effect of numerical noise and choice of simulation parameters on the modeling of beam dynamics, focusing in particular on the investigation of the feedback system requirements of minimum power to damp the instability and frequency bandwidth given a fixed gain. We report on simulation results and discuss the plans for the future improvements of the feedback model.

WEPPP082

Stochastic Cooling in RHIC

kicker, emittance, luminosity, pick-up

2900

J.M. Brennan, M. Blaskiewicz, K. Mernick
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.
Stochastic cooling is used in the Relativistic Heavy Ion Collider to increase the integrated luminosity of ion collisions by a factor of two. The cooling system has been assembled incrementally over the past several years, starting with longitudinal cooling only, then adding cooling in the vertical planes, and recently completed with cooling systems in all three phase space planes of both rings. The system operates from 6 to 9 GHz in the longitudinal planes and from 4.7 to 7.8 GHz in the transverse planes, yielding a cooling rate that overcomes Intra-Beam Scattering at the beginning of a store and reaches equilibrium with a factor of 2 reduction of emittances. The system’s components and mode of operation will be presented along with measurements of the beam parameters during stores with stochastic cooling in operation.

WEPPR001

Experimental Observation of Space Charge Effects in Transverse Bunch Oscillations in the SIS18 Synchrotron

space-charge, synchrotron, ion, damping

2931

V. Kornilov, O. Boine-Frankenheim
GSI, Darmstadt, Germany

Coherent signals from transverse bunch oscillations in the heavy-ion synchrotron SIS18 are used for direct measurements of the space charge effect. The bunch oscillations are excited by a transverse kick and the resulting decoherence is observed. The transverse coherent motion in the SIS18 experiments is strongly affected by space charge. The bunches are long, thus the nonlinear motion in the rf bucket plays an important role and must be taken into account. The signals from the measurements are analyzed and explained using analytical and numerical models.

WEPPR002

Intensity Thresholds for Transverse Coherent Instabilities During Proton and Heavy-Ion Operation in SIS100

impedance, space-charge, proton, synchrotron

2934

V. Kornilov, O. Boine-Frankenheim
GSI, Darmstadt, Germany

The SIS100 synchrotron is the central accelerator of the projected FAIR complex. It should deliver high intensity proton and heavy-ion beams to the different FAIR experiments. Coherent transverse instabilities are a potential intensity-limiting factor in SIS100. In this contribution we give a summary of the different transverse coherent effects in intense bunched beams that can be expected in the SIS100. Some of the main concerns are unstable head-tail modes, the transverse mode coupling instability, and the beam break-up instability. Space charge is an important effect that leads to Landau damping of the head-tail eigenmodes and modifies the transverse mode coupling. The growth times and thresholds for instabilities will be calculated on the basis of the present SIS100 impedance model whose main components are the resistive wall, the kickers, and the broad-band contribution. The corresponding experience from the CERN injector complex will be used for comparisons.

WEPPR005

Study of Electron Cloud Instability in Fermilab Main Injector

electron, injection, 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.

WEPPR007

Simulation Calculation of Longitudinal Beam Distribution in J-PARC MR

injection, beam-loading, acceleration, extraction

2949

K. Hara, T. Koseki, C. Ohmori
KEK, Tokai, Ibaraki, Japan
Y. Sato
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

The J-PARC accelerator complex consists of 3 accelerators, a linear accelerator, a rapid cycle synchrotron (RCS) and a Main Ring (MR) synchrotron. Simulation calculation of longitudinal beam distribution in J-PARC Main Ring has been performed. The effect that RF voltage pattern, space charge, and beam loading gave was examined.

WEPPR008

Simulation of Controlled Longitudinal Emittance Blow-up in J-PARC RCS

emittance, resonance, cavity, extraction

2952

M. Yamamoto, M. Nomura, A. Schnase, T. Shimada, F. Tamura
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda, M. Yoshii
KEK, Ibaraki, Japan
T. Toyama
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

In the J-PARC RCS, a high intensity beam is prepared for the MR. The longitudinal beam emittance at the RCS extraction should be optimized to avoid beam loss during and after MR injection. In order to match the longitudinal emittance shape between the RCS and the MR, it is desirable to enlarge the longitudinal emittance during the RCS acceleration. We have performed the particle tracking simulation for the controlled longitudinal emittance blow up in the RCS.

WEPPR010

Comparison between Electron Cloud Build-Up Measurements and Simulations at the CERN PS

electron, 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.

WEPPR011

Numerical Simulation Study of the Montague Resonance at the CERN Proton Synchrotron

emittance, resonance, space-charge, synchrotron

2958

J. Qiang, R.D. Ryne
LBNL, Berkeley, California, USA
G. Franchetti, I. Hofmann
GSI, Darmstadt, Germany
E. Métral
CERN, Geneva, Switzerland

Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP) under Contract No. DE-AC02-05CH11231.
The Montague resonance provides a coupling between the vertical and the horizontal dynamics of beams and can cause particle losses due to unequal aperture sizes of the accelerator. In this paper, we present a new numerical simulation study of a previous Montague resonance crossing experiment at the CERN PS including detailed three-dimensional space-charge effects and machine nonlinearity. The simulation reproduces the experimental data and suggests that the longitudinal synchrotron motion played an important role in enhancing transverse resonance coupling.

WEPPR012

Simulating High-Intensity Proton Beams in Nonlinear Lattices with PyORBIT

lattice, space-charge, resonance, proton

2961

S.D. Webb, D.T. Abell, D.L. Bruhwiler, J.R. Cary
Tech-X, Boulder, Colorado, USA
V.V. Danilov, A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA
S. Nagaitsev, A. Valishev
Fermilab, Batavia, USA

High-intensity proton linacs and storage rings are essential for a) state-of-the-art neutron source user facilities, b) extending the high-energy physics intensity frontier, c) as a driver to generate pions for a future neutrino factory or muon collider, and d) for transmutation of radioactive waste and associated energy production. For example, Project X at Fermilab will deliver MW proton beams at energies ranging from 3 to 120 GeV. Nonlinear magnetic lattices with large tune spreads and with integrable*, nearly integrable** and chaotic* dynamics have been proposed to maximize dynamic aperture and minimize particle loss. We present PyORBIT*** simulations of proton dynamics in such lattices, including the effects of transverse space charge.
* V. Danilov and S. Nagaitsev, PR ST-AB 13 084002 (2010)
** K. Sonnad and J. Cary, Phys. Rev. E 69 056501 (2004)
*** A. Shishlo, J. Holmes and T. Gorlov, From Proceedings of IPAC '09 351-354

WEPPR013

Design of an Electrostatic Extraction Section for the University of Maryland Electron Ring

extraction, emittance, electron, 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

WEPPR027

Complete Electromagnetic Design of the ESS-Bilbao RFQ Cold Model

rfq, quadrupole, dipole, radio-frequency

2991

A. Vélez, I. Bustinduy, J. Feuchtwanger, N. Garmendia, O. González, I. Madariaga, J.L. Muñoz, D. de Cos
ESS Bilbao, Bilbao, Spain
F.J. Bermejo
Bilbao, Faculty of Science and Technology, Bilbao, Spain
V. Etxebarria, J. Portilla
University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain

In this work, the ESS-Bilbao 352,2 Mhz RFQ Cold Model to be built in the ESS-Bilbao accelerator facility is presented. The Cold Model intends to be a small scale representation of the final 4 meters long RFQ which will be able to accelerate a 75 mA proton beam from 75 keV to 3 MeV. The work shown here covers the complete electromagnetic design process of the Cold Model which will be built in aluminium with a total length of 1 meter. Moreover, in order to find out fabrication tolerances, a longitudinal test modulation in the vane regions similar to the one designed for the final RFQ is included in the Cold Model. This modulation represents also a useful tool in order to test the agreement between measurements and electromagnetic simulations. In addition, a complete parametric study of the RFQ ends and radial matchers is presented as an important design parameter able to adjust the field flatness. Finally, slug tuning rods are also added to be able to test the tuning procedures. A final RFQ Cold Model prototype has been designed and is currently under fabrication.

WEPPR032

Simulation Studies of Adiabatic Thermal Beams in a Periodic Solenoidal Focusing Field

focusing, emittance, vacuum, plasma

3003

C. Chen, T.J. Barton, D.M. Field, K.M. Lang
MIT, Cambridge, Massachusetts, USA

Funding: Research supported by DOE Grant No. DE-FG02-95ER40919, Grant No. DE-FG02-05ER54836, and MIT Undergraduate Research Opportunity Program.
Self-consistent simulations are performed to verify the theoretical predictions of adiabatic thermal beams in periodic solenoidal magnetic focusing fields*,**. In particular, results are obtained for adiabatic thermal beams that do not rotate in the Larmor frame. For such beams, the theoretical predictions of the rms beam envelope, the conservation of the rms thermal emittance, the adiabatic equation of state, and the Debye length are verified in the self-consistent simulations.
*K.R. Samokhvalova, J. Zhou and C. Chen, Phys. Plasma 14, 103102 (2007).
**J. Zhou, K.R. Samokhvalova and C. Chen, Phys. Plasma 15, 023102 (2008).

WEPPR033

Performance of Low-Energy Magnetic Bunch Compression for the ASTA Photoinjector at Fermilab

dipole, emittance, cryomodule, collective-effects

3006

C.R. Prokop, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
B.E. Carlsten
LANL, Los Alamos, New Mexico, USA
M.D. Church
Fermilab, Batavia, USA

Funding: LANL LDRD program, project 20110067DR -U.S. DOE Contract No. DE-FG02-08ER41532 and DE-AC02-07CH11359.
The Advanced Superconducting Test Accelerator (ASTA) at Fermilab incorporates a magnetic bunch compressor chicane to compress the 40-MeV electron bunches generated in the photoinjector. In this paper, we present a numerical analysis and parametric study of the bunch compressor's performance for various operating scenarios. The beam dynamics simulations, carried out with Astra, Impact-Z and CSRTrack, are compared against each other. Finally, an operating regime with low phase space dilutions is suggested based on the simulation results.

WEPPR034

Longitudinal Phase Space Measurement for the Advanced Superconducting Test Accelerator Photoinjector

emittance, diagnostics, cavity, collimation

3009

C.R. Prokop, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
M.D. Church, Y.-E. Sun
Fermilab, Batavia, USA

Funding: LANL LDRD program, project 20110067DR -U.S. DOE Contract No. DE-FG02-08ER41532 and DE-AC02-07CH11359.
The Advanced Superconducting Test Accelerator (ASTA) at Fermilab uses a high-brightness photoinjector capable of producing electron bunches with charges up to 3.2 nC, to be used in support of a variety of advanced accelerator R&D experiments. The photoinjector incorporates an extensive diagnostics suites including a single-shot longitudinal-phase-space diagnostics composed of a horizontally deflecting cavity followed by a vertical spectrometer. In this paper, we present the design, optimization, and performance analysis (including detrimental collective effects) of the longitudinal phase space diagnostics and especially compare two possible choices of deflecting cavity frequencies.

WEPPR035

Optimization of Drive-bunch Current Profile for Enhanced Transformer Ratio in Beam-driven Acceleration Techniques

acceleration, electron, 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.

WEPPR047

The Effect of Non-Zero Closed Orbit on Electron-Cloud Pinch Dynamics

electron, quadrupole, proton, dipole

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.

WEPPR059

The Simulation of Ion Cloud Build-up in Electron Storage Ring

ion, electron, 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.

WEPPR061

Thresholds of Longitudinal Single Bunch Instability in Single and Double RF Systems in the CERN SPS

impedance, damping, synchrotron, emittance

3066

T. Argyropoulos, T. Bohl, J. Esteban Muller, E.N. Shaposhnikova, H. Timko
CERN, Geneva, Switzerland
C.M. Bhat
Fermilab, Batavia, USA

A fourth harmonic RF system is used in the SPS as a Landau cavity, in order to stabilize the high intensity LHC proton beam against the longitudinal instabilities. Numerous studies proved that operating the two RF systems, through the whole cycle, in bunch shortening mode is necessary to provide a good quality beam at extraction to the LHC. Furthermore, it was shown that the choice of RF parameters as voltage amplitude ratio and relative phase are critical for the beam stability. This paper presents the results of single bunch measurements performed in single and double RF systems with various RF settings and compares them with the results of macroparticle simulations for the SPS impedance model.

WEPPR062

The Mode Matching Method Applied to Beam Coupling Impedance Calculations of Finite Length Devices

impedance, coupling, cavity, resonance

3069

N. Biancacci, E. Métral, B. Salvant
CERN, Geneva, Switzerland
M. Migliorati, L. Palumbo
URLS, Rome, Italy
V.G. Vaccaro
Naples University Federico II and INFN, Napoli, Italy

The infinite length approximation is often used to simplify the calculation of the beam coupling impedance of accelerator elements. This is expected to be a reasonable assumption for devices whose length is greater than the transverse dimension but may be less accurate approximation for segmented devices. This contribution presents the study of the beam coupling impedance in the case of a finite length device: a cylindrical cavity loaded with a toroidal slab of material. In order to take into account the finite length we will decompose the field in the cavity and in the beam pipe into a set of orthonormal modes and apply the mode matching method to obtain the impedance. To validate our method, we will present comparisons between analytical formulas and 3D electromagnetic CST simulations as well as applications to the impedance of short beam pipe inserts, where the longitudinal and transverse dimensions are difficult to model in numerical simulations.

WEPPR064

Very Short Range Wake in Strongly Tapered Disk Loaded Waveguide Structures

wakefield, linac, FEL, impedance

3072

A. Grudiev
CERN, Geneva, Switzerland

Electron bunches are very short, both in linear collider and in X-FEL projects. Furthermore, typical disk-loaded waveguide structures used for particle acceleration are tapered. For example in CLIC, in order to achieve high accelerating gradient, the structure is only 26 cells long, which results in strong tapering. In this paper, very short range wake is investigated in the regime where the number of cells needed to arrive at steady state is much larger than the number of cells in a single tapered structure. In this case the very short range wake is dominated by the wake from the smallest aperture. The results of an analytical model and numeric solutions are compared.

WEPPR065

Electromagnetic Simulations of the Impedance of the LHC Injection Protection Collimator

impedance, injection, vacuum, wakefield

3075

B. Salvant, V. Baglin, B. Goddard, A. Grudiev, E. Métral, M.A. Timmins
CERN, Geneva, Switzerland

During the 2011 LHC run, significant vacuum and temperature increase were observed at the location of the LHC injection protection collimators (TDI) during the physics fills. Besides, measurements of the LHC transverse tune shift while changing the TDI gap showed that the impedance of the TDI was significantly higher than the LHC impedance model prediction based on multilayer infinite length theory. This contribution details the electromagnetic simulations performed with a full 3D model of the TDI to obtain both longitudinal and transverse impedances and their comparison with measured observables.

WEPPR067

Study of Fundamental Mode Multipolar Kicks in Double- and Single-feed Power Couplers for the CLIC Main Linac Accelerating Structure

linac, emittance, multipole, cavity

3081

A. Latina, A. Grudiev, D. Schulte
CERN, Geneva, Switzerland

Multipolar kicks from the fundamental mode have been calculated in the CLIC baseline accelerating structure with double–feed input and output power couplers. The influence of such multipolar kicks on the main linac beam dynamics has been investigated. Furthermore, an alternative design of the couplers with single-feed has been studied and compared with the double-feed. Such an alternative would significantly simplify the waveguide system of the main linac but potentially introduce an harmful dipolar kick from the fundamental mode. The geometry of the coupler has been optimized in order to minimize such a dipolar kick and keep it below threshold levels determined with beam dynamics simulations. Influence of the higher order multipoles has been investigated as well and acceptable levels have been determined.

WEPPR069

Measurements and Simulations of Transverse Coupled-Bunch Instability Rise Times in the LHC

injection, octupole, feedback, impedance

3087

N. Mounet, R. Alemany-Fernandez, W. Höfle, D. Jacquet, V. Kain, E. Métral, L. Ponce, S. Redaelli, G. Rumolo, R. Suykerbuyk, D. Valuch
CERN, Geneva, Switzerland

In the current configuration of the LHC, multibunch instabilities due to the beam-coupling impedance would be in principle a critical limitation if they were not damped by the transverse feedback. For the future operation of the machine, in particular at higher bunch intensities and/or higher number of bunches, one needs to make sure the coupled-bunch instability rise times are still manageable by the feedback system. Therefore, in May 2011 experiments were performed to measure those rise times and compare them with the results obtained from the LHC impedance model and the HEADTAIL wake fields simulation code. At injection energy, agreement turns out to be very good, while a larger discrepancy appears at top energy.

WEPPR070

Beam Coupling Impedance Simulations of the LHC TCTP Collimators

impedance, cavity, coupling, vacuum

3090

H.A. Day, R.M. Jones
UMAN, Manchester, United Kingdom
F. Caspers, A. Dallocchio, L. Gentini, A. Grudiev, E. Métral, B. Salvant
CERN, Geneva, Switzerland

As part of an upgrade to the LHC collimation system, 8 TCTP and 1 TCSG collimators are proposed to replace existing collimators in the collimation system. In an effort to review all equipment placed in the accelerator complex for potential side effects due to collective effects and beam-equipment interactions, beam coupling impedance simulations are carried out in both the time-domain and frequency-domain of the full TCTP design. Particular attention is paid to trapped modes that may induce beam instabilities and beam-induced heating due to cavity modes of the device.

WEPPR071

Evaluation of the Beam Coupling Impedance of New Beam Screen Designs for the LHC Injection Kicker Magnets

impedance, kicker, coupling, injection

3093

H.A. Day, R.M. Jones
UMAN, Manchester, United Kingdom
M.J. Barnes, F. Caspers, H.A. Day, E. Métral, B. Salvant
CERN, Geneva, Switzerland

During the 2011 run of the LHC there was a measured temperature increase in the LHC Injection Kicker Magnets (LHC-MKI) during operation with 50ns bunch spacing. This was suspected to be due to increased beam-induced heating of the magnet due to beam impedance. Due to concerns about future heating with the increased total intensity to nominal and ultimate luminosities a review of the impedance reduction techniques within the magnet was required. A number of new beam screen designs are proposed and their impedance evaluated. Heating estimates are also given with a particular attention paid to future intensity upgrades to ultimate and HL-LHC parameters.

WEPPR073

Effects of an Asymmetric Chamber on the Beam Coupling Impedance

impedance, kicker, wakefield, synchrotron

3099

C. Zannini, K.S.B. Li, G. Rumolo
CERN, Geneva, Switzerland
C. Zannini
EPFL, Lausanne, Switzerland

The wake function of an accelerator device appears to have a constant term if the geometry of the device is asymmetric or when the beam passes off axis in a symmetric geometry. Its contribution can be significant and has to be taken into account. In this paper a generalized definition of the impedance/wake is presented to take into account also this constant term. An example of a device where the constant term appears is analyzed. Moreover, the impact of a constant wake on the beam dynamics is discussed and illustrated by a HEADTAIL simulation.

WEPPR074

Effect of the TEM Mode on the Kicker Impedance

impedance, kicker, coupling, vacuum

3102

C. Zannini, G. Rumolo, V.G. Vaccaro
CERN, Geneva, Switzerland
C. Zannini
EPFL, Lausanne, Switzerland

The kickers are major contributors to the CERN SPS beam coupling impedance. As such, they may represent a limitation to increasing the SPS bunch current in the frame of a luminosity upgrade of the LHC. The C-Magnet supports a transverse electromagnetic (TEM) mode due to the presence of two conductors. Due to the finite length of the structure this TEM mode affects the impedance below a certain frequency (when the penetration depth in the ferrite becomes comparable to the magnetic circuit length). A theoretical model was developed to take into account also the impedance contribution due to the TEM mode. The model is found to be in good agreement with CST 3D electromagnetic (EM) simulations. It allows for generic terminations in the longitudinal direction. An example of kicker is analyzed taking into account also the external cables.

WEPPR075

Monitoring the Progress of LHC Electron-Cloud Scrubbing by Benchmarking Simulations and Pressure-Rise Observations

electron, 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.

WEPPR077

Analysis of Long-range Wakefields in CLIC Main Linac Accelerating Structures with Damping Loads

wakefield, damping, HOM, resonance

3111

G. De Michele
Paul Scherrer Institut, Villigen, Switzerland
G. De Michele
EPFL, Lausanne, Switzerland
A. Grudiev
CERN, Geneva, Switzerland

The baseline design of the CLIC accelerating structure foresees a moderate detuning and heavy damping of high order modes (HOMs), which are the source of long-range transverse wakefields. Such unwanted fields produce bunch-to-bunch instabilities so the HOMs must be suppressed. In order to damp these modes, the CLIC RF structure is equipped with lossy material inserted into four rectangular waveguides coupled to each accelerating cell. The lossy material absorbs EM (electromagnetic) wave energy with little reflection back to the accelerating cells. In the past, computations of the long-range wake of CLIC accelerating modes have been done using perfectly absorbing boundaries to terminate the damping waveguides. In this paper, 3D EM simulations of CLIC baseline accelerating structure with HOMs damping loads will be presented. A comparison between different EM codes (GdfidL, CST PARTICLE STUDIO®) will be discussed as well as the analysis of different types of absorbing materials with respect to the wakefields damping.

WEPPR081

The Collective Effects of the Short Pulsed X-Ray (SPX) System in the Advanced Photon Source Upgrade

impedance, cavity, emittance, collective-effects

3117

Y.-C. Chae, M. Borland
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.
The Advanced Photon Source is a 7-GeV hard x-ray synchrotron light source. The APS Upgrade specifies a short-pulse x-ray (SPX) as well as additional beamlines delivering higher brightness and flux. In order to achieve this goal we plan to use S-band superconducting cavities. The performance of such a system based on the zero-current simulation is well established; here, we included the effect of wakefields generated by the SPX system. While the SPX system is off, we are interested in how much current we can store in the single bunch, because the SPX contributes a significant amount of broadband impedance to the ring. With the SPX system on, we are interested in how much vertical emittance will increase, which in turn will enlarge the x-ray pulse length. We report the results of both cases when the SPX system is installed in the ring for the APS Upgrade.

WEPPR088

Modeling and Simulation of Retarding Field Analyzers at CESRTA

electron, dipole, 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, emittance, electron, 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, electron, 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.

WEPPR092

Beam Ion Instability in ILC Damping Ring with Multi-gas Species

ion, vacuum, damping, lattice

3150

L. Wang, M.T.F. Pivi
SLAC, Menlo Park, California, USA

Ion induced beam instability is one critical issue for the electron damping ring of the International Linear Collider (ILC) due to its ultra small emittance of 2 pm. The beam ion instability with various beam filling patterns for the latest lattice DTC02 is studied using code IONCLOUD. The code has been benchmarked with SPEAR3 experimental data and there is a good agreement between the simulation and observations. It uses the optics from MAD and can handle arbitrary beam filling pattern and vacuum. Different from previous studies, multi-gas species have been used simultaneously in the simulation. This feature makes it more accurate.

WEPPR096

Recirculating Beam Breakup Study for the 12 GeV Upgrade at Jefferson Lab

HOM, cryomodule, linac, cavity

3162

I. Shin, S. Ahmed, R.M. Bodenstein, S.A. Bogacz, T. Satogata, M. Stirbet, H. Wang, Y. Wang, B.C. Yunn
JLAB, Newport News, Virginia, USA
I. Shin
University of Connecticut, Storrs, Connecticut, USA

Two new high gradient C100 cryostats with a total of 16 new cavities were installed at the end of the CEBAF south linac during the 2011 summer shutdown as part of the 12 GeV upgrade project at Jefferson Lab. We ran recirculating beam breakup (BBU) study in November 2011 to evaluate CEBAF low energy performance, measure transport optics, and evaluate BBU thresholds due to higher order modes (HOMs) in these cavities. This paper discusses the experiment setup, cavity measurements, machine setup, optics measurements, and lower bounds on existing CEBAF C100 BBU thresholds established by this experiment.

WEPPR097

Comparing New Models of Transverse Instability with Simulations

space-charge, coupling, synchrotron, wakefield

3165

M. Blaskiewicz
BNL, Upton, Long Island, New York, USA

Recently, Balbekov* has produced an ordinary integro-differential equation that approximates the Vlasov equation for beams with wakefields and large space charge tune shift. The present work compares this model with simulations. In particular, the claim that certain types of transverse wakes cannot lead to mode coupling instabilities, which contradicts earlier work**, is explored
* V. Balbekov, PRSTAB, 14, 094401 (2011).
** M. Blaskiewicz, PRSTAB 1, 044201 (1998).

WEPPR098

Two Dimensional Impedance Analysis of Segmented IVU

impedance, vacuum, undulator, storage-ring

3168

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

Funding: Work supported by DOE contract No: DE-AC02-98CH10886
Segmented Adaptive-Gap In-Vacuum Undulator (IVU) with variable magnetic gap along z-axis is considered as an alternative to the Constant Gap IVU (7mm gap) for the NSLS-II storage ring. The length of the Constant Gap IVU for a given minimum gap is limited by the beam stay clear aperture. With the new conceptual design of IVU the magnetic gap can be varied along z-axis and its minimum gap can be reduced down to 5.25mm in the center of the structure for the same stay clear aperture. Beam impedance becomes an important issue since the new design consists of several magnet gaps. Wakepotentials and impedances have been analyzed for a new type of IVU and the results compared with data for the reference geometry which is the Constant Gap IVU.

WEPPR100

Short-Range Wakefields of Slowly Tapered Structures

wakefield, cavity, focusing, factory

3174

B. Podobedov
BNL, Upton, Long Island, New York, USA

We present new analytical results for short-range geometric wakefields of slowly tapered accelerator structures in 2D geometry.

THXB01

Interaction of Muon Beam with Plasma Developed During Ionization Cooling

plasma, wakefield, electron, 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]

THYB01

Beam-beam Limit in a Hadron Collider

luminosity, emittance, resonance, collider

3208

K. Ohmi
KEK, Ibaraki, Japan

Beam-beam limit phenomenon is observed in degradation of luminosity lifetime and/or beam life time in hadron colliders, especially in LHC. We focus the luminosity degradation in this paper. Various effects to degrade the luminosity grow severe in a high beam intensity. Coherent beam-beam instability, incoherent beam-beam emittance growth and those cupeled with lattice errors, external noises, intra-beam scattering. The beam-beam limit in an ideal machine and a machine with above errors is discussed with theory and simulation. Experimental results are reviewed and compare with the theory and simulations.

Slides THYB01 [4.712 MB]

THAP01

Secondary-electron Emission from Hydrogen-terminated Diamond

electron, vacuum, high-voltage, linac

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]

THEPPB001

Design and Fabrication of The ESS-Bilbao RFQ Prototype Models

rfq, vacuum, laser, alignment

3228

I. Bustinduy, F.J. Bermejo, J. Feuchtwanger, N. Garmendia, A. Ghiglino, O. González, P.J. González, I. Madariaga, J.L. Muñoz, I. Rueda, F. Sordo Balbin, A. Vélez, D. de Cos
ESS Bilbao, Bilbao, Spain
V. Etxebarria, J. Portilla
University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain
A. Garbayo
AVS, Eibar, Gipuzkoa, Spain
S. Jolly
UCL, London, United Kingdom
S.R. Lawrie, A.P. Letchford
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
J.K. Pozimski, P. Savage
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

As part of the development of the ESS-Bilbao Accelerator in Spain, two different sets of radio frequency quadrupole (RFQ) models have been developed. On one hand, a set of four oxygen free high conductivity copper weld test models has been designed and manufactured, in order to test different welding methods as well as other mechanical aspects involved in the fabrication of the RFQ. On the other hand, a 352.2 MHz four vane RFQ cold model, with a length of 1 meter, has been designed and built in Aluminum. It serves as a good test bench to investigate the validity of different finite element analysis (FEA) software packages. This is a critical part, since the design of the final RFQ will be based on such simulations. The cold model also includes 16 slug tuners and 8 couplers/pick-up ports, which will allow to use the bead-pull perturbation method, by measuring the electric ﬁeld profile, Q-value and resonant modes. In order to investigate fabrication tolerances, the cold model also comprises a longitudinal test modulation in the vanes, which is similar to the one designed for the final RFQ.

THEPPB002

High-Fidelity 3D Modulator Simulations of Coherent Electron Cooling Systems

electron, ion, plasma, 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).

THEPPB003

A 1 GeV CW FFAG High Intensity Proton Driver

space-charge, emittance, cyclotron, focusing

3234

S.L. Sheehy
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
C. Johnstone
Fermilab, Batavia, USA

The drive for high beam power, high duty cycle, and reliable beams at reasonable cost has focused world attention on fixed-field accelerators, notably Fixed-Field Alternating Gradient accelerators (FFAGs). High-intensity GeV proton drivers are of particular interest, as these encounter duty cycle and space-charge limits in the synchrotron and machine size concerns in the weaker-focusing cyclotron. Recently, the concept of isochronous orbits has been explored and developed for non-scaling FFAGs using powerful new methodologies in FFAG accelerator design. These new breeds of FFAGs have been identified by international collaborations for serious study thanks to their potential applications including Accelerator Driven Subcritical Reactors (ADS) and Accelerator Transmutation of Waste. The extreme reliability requirements for ADS mandate CW operation capability and the FFAG’s strong focusing, particularly in the vertical, will serve to mitigate the effect of space charge (as compared with the weak-focusing cyclotron). This paper reports on these new advances in FFAG accelerator technology and presents a stable, 0.25-1GeV isochronous FFAG for an accelerator driven subcritical reactor.

THEPPB004

Development of a Cryocatcher-System for SIS100

ion, vacuum, heavy-ion, cryogenics

3237

L.H.J. Bozyk, H. Kollmus, P.J. Spiller
GSI, Darmstadt, Germany

Funding: Work supported by EU (FP7 workpackage COLMAT) and GP-HIR – Graduate Program for Hadron and Ion Research at GSI.
The main accelerator SIS100 of the FAIR-facility will provide heavy ion beams of highest intensities using intermediate charge state heavy ions. Ionization beam loss is the most important loss mechanism, therefore, a special synchrotron layout has been developed, which includes a dedicated cold ion catcher system which provides almost hundred percent catching efficiency. Dynamic vacuum effects are suppressed effectively by means of special low desorption yield surfaces. A prototype of the cryocatcher system has been developed, constructed and tested with heavy ion beam from SIS18. It is a work package of the EU-FP-7 project COLMAT. Results from these tests are presented as well as implications for the production of the 60 SIS100 cryocatchers.

THEPPB010

Simulation of Plasma Window for Gas Target of Neutron Source

plasma, neutron, vacuum, target

3251

S. Huang, S. BenLiang, Y.R. Lu, K. Zhu
PKU/IHIP, Beijing, People's Republic of China

the demand of intense mono-energy fast neutron beams grow quickly as various applications of neutron are improved. Utilizing the reaction and based on small accelerators especially the modern radio-frequency quadrupole (RFQ) accelerators to get several mA of ion beam to energies in the low MeV range, or even just only connecting to a ion source with LEBT, the neutron source can be as compact as possible to get intense fast neutrons. Traditional gas target of high pressure is sealed by several thick metal foil from the vacuum environment, which will decrease and disperse the energy of the ion beams, and at the same time reduce the strength and cause the production of rays. In the other aspects, the foil window could be damaged with short service life result from the high heat flux of the ion beam injection. To prevent of these problems, a plasma window is designed to maintain a high pressure gap between the gas target (several bar) and the vacuum vessel, with no material window at all. In this article both the computational simulation and experiment results of the plasma window will be included.

THEPPB013

Progress in Modeling Arcs

plasma, electron, cavity, ion

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.

THEPPB015

Examples for 3D CAD Models at the European XFEL

survey

3266

L. Hagge, J. Kreutzkamp, S. Lang, S. Sühl, N. Welle
DESY, Hamburg, Germany

This presentation analyses usage and benefits of 3D models in the planning and design of the European XFEL. 3D models are used in planning, design and integration activities, and they range from detailed models of individual accelerator components up to an integration model of the entire facility. Through DESY’s Engineering Data Management System, all members of the project have interactive access to all the models. Because of this general availability, the models are widely used and well-accepted as communication tools. They support vision sharing, and they help discovering and resolving design issues early (e. g. clashes). The presentation explains the modeling technique and shows (animated) examples of model usage. It also includes an animated virtual tour of the entire XFEL facility, entering at the injector complex and emerging in the experiment hall.

THPPC001

Simulation and Design of a 70 MeV Cyclotron RF System

cyclotron, cavity, vacuum, resonance

3269

G. Gold, R.R. Johnson, B.F. Milton, V. Sabaiduc
BCSI, Vancouver, BC, Canada

The electromagnetic and mechanical design of the resonant cavity for a 70 MeV compact commercial cyclotron has been conducted by Best Cyclotron Systems Inc. Various resonator configurations have been studied for a radial, single-stem design and an optimal solution was selected with excellent electromagnetic properties and minimized construction and operational cost. Rapid model iterations during the design, using CST Microwave Studio and ANSYS, allowed for accurate tuning of geometry to precisely define the shape of the accelerating voltage profile, surface current distribution, and total power loss. The RF system of the BEST 70p cyclotron will operate at the fourth harmonic with two λ/2 separated resonant cavities shielded at the center allowing for beam modulation techniques to be applied through phase modulation of the accelerating voltage.

THPPC002

Design and Construction of Turnkey Linacs as Injectors for Light Sources

beam-loading, electron, 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.

THPPC011

Design of an Accelerating Structure for a 500 GeV CLIC using Ace3P

damping, linac, wakefield, beam-loading

3296

K.N. Sjobak, E. Adli
University of Oslo, Oslo, Norway
A. Grudiev, W. Wuensch
CERN, Geneva, Switzerland

Funding: Research Council of Norway
An optimized design of the main linac accelerating structure for a 500 GeV first stage of CLIC is presented. A similar long-range wakefield suppression scheme as for 3 TeV CLIC based on heavy waveguide damping is adopted. The accelerating gradient for the lower energy machine is 80 MV/m. The 500 GeV design has larger aperture radius in order to increase the maximum bunch charge and length which is limited by the short-range wakefields. The cell geometries have been optimized using a new parametric optimizer for Ace3P and details of the RF cell design are described. Parameters of the full structure are calculated and optimized using a power flow equation.

THPPC012

Impedance Computation of Main Components in CSNS/RCS

impedance, cavity, extraction, vacuum

3299

Y. Li, L. Huang, Z.P. Li, Y.D. Liu, N. Wang, S. Wang
IHEP, Beijing, People's Republic of China

The rapid cycling synchrotron (RCS) of the China spallation neutron source (CSNS) is a high intensity proton accelerator. The study on the coupling impedance in the ring plays an important role in the stability of the beam. The impedance of the main vacuum components in the RCS ring, such as RF cavities, bellows, ports of vacuum pumps, collimator etc, was calculated by using numerical methods. Meantime, RF shielding of bellows, collimators and ports of vacuum pumps are considered. The impact of the busbar configuration on RF cavities and beams was estimated by impedance calculation.

THPPC015

Design of a Four-vane 325 MHz RFQ Cold Model at Tsinghua University

rfq, cavity, dipole, resonance

3308

L. Du, J.C. Cai, X. Guan, Q.Z. Xing
TUB, Beijing, People's Republic of China

Funding: Work supported by National Natural Science Foundation of China (Project 11175096).
The design of a Radio Frequency Quadrupole (RFQ) accelerator cold model at Tsinghua University is presented in this paper. The 1-meter-long aluminium cold model is chosen to be the same as the low-energy part of the 3-meter-long RFQ for the Compact Pulsed Hadron Source (CPHS) project at Tsinghua University. This cold model will be used mainly for the RFQ field study and education. It will work at the RF frequency of 325 MHz. All the simulations are finished by the SUPERFISH and MAFIA codes.

THPPC022

Enhanced Coupling Design of a Detuned Damped Structure for CLIC

wakefield, coupling, damping, dipole

3323

A. D'Elia, A. Grudiev, V.F. Khan, W. Wuensch
CERN, Geneva, Switzerland
T. Higo
KEK, Ibaraki, Japan
R.M. Jones
UMAN, Manchester, United Kingdom

The key feature of the improved coupling design in the Damped Detuned Structure (DDS) is focused on the four manifolds. Rectangular geometry slots and rectangular manifolds are used. This results in a significantly stronger coupling to the manifolds compared to the previous design. We describe the new design together with its wakefield damping properties.

THPPC026

A Transverse Deflecting Cavity for the Measurement of Short Low Energy Bunches at EBTF

cavity, coupling, electron, 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.

THPPC027

Measurement of the Dynamic Response of the CERN DC Spark System and Preliminary Estimates of the Breakdown Turn-on Time

impedance, vacuum, cathode, radio-frequency

3338

N.C. Shipman, R.M. Jones
UMAN, Manchester, United Kingdom
S. Calatroni, W. Wuensch
CERN, Geneva, Switzerland

The new High Rep Rate (HRR) CERN DC Spark System has been used to investigate the current and voltage time structure of a breakdown. Simulations indicate that vacuum breakdowns develop on ns timescales or even less. An experimental benchmark for this timescale is critical for comparison to simulations. The fast rise time of breakdown may provide some explanation of the particularly high gradients achieved by low group velocity, and narrow bandwidth, accelerating structures such as the T18 and T24. Voltage and current measurements made with the previous system indicated that the transient responses measured were dominated by the inherent capacitances and inductances of the DC spark system itself. The bandwidth limitations of the HRR system are far less severe allowing rise times of around 12ns to be measured.

THPPC028

Kinetic Modeling of RF Breakdown in High-Pressure Gas-filled Cavities

plasma, electron, 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.

THPPC031

Commissioning of a 1.3-GHz Deflecting Cavity for Phase-Space Exchange at the Argonne Wakefield Accelerator

cavity, wakefield, klystron, diagnostics

3350

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, M.M. Rihaoui
Northern Illinois University, DeKalb, Illinois, USA

Funding: Work supported by DOE awards FG-02-08ER41532 and DE-AC02-06CH11357.
A 1/2-1-1/2 cell normal-conducting 1.3-GHz deflecting cavity was recently installed at the Argonne Wakefield Accelerator. The cavity will soon be included in a transverse-to-longitudinal phase space exchanger that will eventually be used to shaped the current profile of AWA electron bunches in support of dielectric wakefield experimentS with enhanced transformer ratio. In this paper we report on the initial commissioning of the deflecting cavity including rf-conditioning and beam-based measurement of the deflecting strength.

THPPC033

Progress on a Cavity with Beryllium Walls for Muon Ionization Cooling Channel R&D

cavity, coupling, electron, vacuum

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.

THPPC040

Improved RF Design for an 805 MHz Pillbox Cavity for the US MuCool Program

cavity, coupling, ion, multipactoring

3371

Z. Li, C. Adolphsen, L. Ge
SLAC, Menlo Park, California, USA
D.L. Bowring, D. Li
LBNL, Berkeley, California, USA

Funding: Work supported by US DOE under contract number DE-AC02-05CH11231, and DE-AC02-76SF00515.
Normal conducting RF cavities are required to operate at high gradient in the presence of strong magnetic field in muon ionization cooling channels for a Muon Collider. Experimental studies using an 805 MHz pillbox cavity at MTA of Fermilab has shown significant degradation in gradient performance and damage in the regions that are correlated with high RF fields in magnetic field up to 4 Tesla. These effects are believed to be related to the dark current and/or multipacting activities in the presence of external magnetic field. To improve the performance of the cavity, a new RF cavity with significantly lower surface field enhancement was designed, and will be built and tested in the near future. Numerical analyses of multipacting and dark current were performed using the 3D parallel code Track3P for both the original and new improved cavity profiles in order to gain more insight in understanding of the gradient issues under strong external magnetic field. In this paper, we will present the improved RF design and the dark current and multipacting analyses for the 805 MHz cavity.

THPPC043

Cold Test of an L-band, 2-Cell PWT Photoelectron

cavity, gun, vacuum, electron

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.

THPPC045

Rapidly Tunable RF Cavity for Accelerators

cavity, acceleration, synchrotron, vacuum

3386

D.J. Newsham, N. Barov
Far-Tech, Inc., San Diego, California, USA

Funding: Work supported by the DOE-SBIR program, High Energy Physics Department.
The performance and range efficient use of rapidly cycling accelerators would be improved with the fast frequency tuning and associated variable phase change provided by a tunable rf cavity. The progress in developing a cavity that can be tuned by as much as 10 percent in frequency in less than 100 nanoseconds is presented.

THPPC049

Progress on the MICE 201 MHz RF Cavity at LBNL

cavity, coupling, resonance, electron

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.

THPPC057

S-band High Power RF System for 10 GeV PAL-XFEL

coupling, cavity, klystron, linac

3419

W.H. Hwang, J.Y. Huang, Y.D. Joo, H.-S. Kang, H.-G. Kim, S.H. Kim, H.-S. Lee, Y.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea

In PAL, We are constructing a 10GeV PxFEL project. The output power of the klystron is 80 MW at the pulse width of 4 ㎲ and the repetition rate of 120 Hz. In high power operation, it is important to decrease the rf electric field to protect rf break-down in high power rf components. To obtain the maximum beam, we must reduce the phase difference between waveguide branches including accelerating structure and minimize the environment influences. This paper describes the waveguide system and high power rf components for the PxFEL.

THPPC059

Design of SLED System with Dual Side-wall Coupling Irises and Biplanar Power Splitter for PAL XFEL

coupling, klystron, cavity, factory

3425

Y.D. Joo, I. Hwang, C. Kim, B.-J. Lee
PAL, Pohang, Kyungbuk, Republic of Korea

The SLED system of the PAL XFEL is required to be operated with the RF input power of 80 MW and the pulse width of 4 us. The high RF dose from the RF breakdown at the coupling holes and power splitter prohibits that the original design of the SLED serve this operation condition. To reduce the gradient at the cavity coupling structure, the concept of dual side-wall coupling irises is introduced. In addition, the 3dB splitter is modified with the concept of biplanar coupler structure.

THPPC080

The Development of LLRF System at PAL

LLRF, controls, cavity, radio-frequency

3473

K.-H. Park, H.S. Han, Y.-G. Jung, D.E. Kim, H.-G. Lee, H.S. Suh
PAL, Pohang, Kyungbuk, Republic of Korea
J.-S. Chai, H.W. Kim, Y.S. Lee
SKKU, Suwon, Republic of Korea
B.-K. Kang
POSTECH, Pohang, Kyungbuk, Republic of Korea

The Super Conducting Radio Frequency (SCRF) systems will be installed for PLS-II. The PAL has been carrying out the design of the low level radio frequency (LLRF) system for the SCRF control using the digital technologies. The requirements of the LLRF system are to maintain the field stability in a cavity within ±0.75% in amplitude and 0.35° in phase. The LLRF system includes the analog front-end, analog and digital board (ADC, DAC, DSP, FPGA, etc.), clock generation and distribution, and so on. The control algorithm will be implemented by the VHDL. The hardware design of the LLRF for PLS-II, simulation and test results were described in the paper.

THPPC090

Robust Control of a Two-Input Two-Output (TITO) Multistate Cavity RF System ith Mismatched Uncertainty

cavity, controls, feedback, LLRF

3494

S. Kwon, M.S. Prokop, A. Scheinker
LANL, Los Alamos, New Mexico, USA

A RF cavity is well modeled as a linear two input two output (TITO) system in the Inphase/Quadrature (IQ) coordinates and is both controllable and observable. Whether it is due to the beam loading or Lorentz force detuning of a superconducting cavity, a cavity frequency detuning can be modeled as a matched uncertainty. The cavity field of a TITO cavity system with a matched uncertainty is controlled by output feedback or state feedback, whose error bound is made arbitrary small. Because of the building cost of the RF system, the single RF source (single klystron)-multicavity structure is sometimes used. This structure is described as a two-input multiple-output (TIMO) system. The control problem is not a simple extension of the single TITO system. Though the controllability and observability are preserved, the matched uncertainty of the TITO cavity system caused by cavity detuning becomes a mismatched uncertainty. The error bound of outputs is made arbitrary small by a control, only boundedness of the cavity fields of each TITO subsystem is guaranteed. In this paper, the properties of the TITO and the TIMO cavity RF systems are investigated.

THPPD001

Stretched-wire Measurements of Small Bore Multipole Magnets

multipole, quadrupole, permanent-magnet, alignment

3500

G. Lebec, J. Chavanne, C. Penel
ESRF, Grenoble, France

Stretched-wire (SW) measurements of magnetic multipoles have been performed at radii ranging from 0.5 mm to 4 mm, with an accuracy of 10^-3 of the main multipole component. Theoretical aspects of SW measurements were investigated. The processing of the measured signals is based on a least square approach, instead of the Fourier transform widely used for rotating coil measurements. It allows correcting numerically the position errors of the SW and designing SW trajectory which are not sensitive to the main multipole, as with “bucked” rotating coils. This SW measurement bench was developed for the characterization of new ESRF magnets. It has been tested first with large aperture multipole magnets. An accuracy of 10^-4 has been obtained for a measurement radius of 30 mm. There is a demand in the magnetic measurement community for measuring small bore multipole magnets, with radius smaller than 5 mm. A small permanent magnet quadrupole was built in order to test the bench at small measurement radii.

THPPD014

Design and Performance of Various kinds of Corrector Magnets for the Taiwan Photon Source

feedback, booster, vacuum, power-supply

3524

C.Y. Kuo, C.-H. Chang, M.-H. Huang, C.-S. Hwang, J.C. Jan, F.-Y. Lin
NSRRC, Hsinchu, Taiwan

Three types of DC corrector magnets will be installed in the booster ring (BR), LINAC to booster (LTB) and booster to storage ring (BTS) in the Taiwan photon source (TPS). These DC corrector magnets have different gap sizes, iron lengths and field strengths for different bending angles to optimize the electron beam. The DC magnetic fields are simulated by TOSCA 2D/3D static field analysis and optimum processes are discussed. An AC steering fast feedback corrector (FFC) combines horizontal and vertical dipole fields for the fast feedback correction in the storage ring (SR). The field variation with the alternating current in the 300Hz frequency of the FFC magnet is simulated by the Opera 3d ELEKTRA/SS analysis module to estimate the operating current. This paper will be presented about features, design concept and results of field measurement of these corrector magnets.
NSRRC, 10¹ Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan

THPPD020

Test of a 1.8 Tesla, 400 Hz Dipole for a Muon Synchrotron

dipole, power-supply, synchrotron, acceleration

3542

D.J. Summers, L.M. Cremaldi, T.L. Hart, L.P. Perera, M. Reep
UMiss, University, Mississippi, USA
S.U. Hansen, M.L. Lopes
Fermilab, Batavia, USA
J. Reidy
Oxford High School, Mississippi, USA
H. Witte
BNL, Upton, Long Island, New York, USA

Funding: Supported by DE-FG05-91ER40622.
A 1.8 Tesla dipole magnet using 0.011" AK Steel TRAN-COR H-1 grain oriented silicon steel laminations has been constructed as a prototype for a muon synchrotron ramping at 400 Hz. Following the practice in large 3 phase transformers and our own OPERA-2D simulations, joints are mitered to take advantage of the magnetic properties of the steel which are most effective in the direction in which the steel was rolled. Measurements with a Hysteresigraph 5500 and Epstein Frame show a high magnetic permeability which minimizes stored energy in the yoke so the magnet can ramp quickly with modest voltage. A power supply with a fast IGBT switch and a polypropylene capacitor was constructed. Coils are wound with 12 gauge copper wire which will eventually be cooled with with water flowing in stainless steel tubes. The magnetic field was measured with an F. W. Bell 5180 peak sensing Hall Probe connected to a Tektronics TDS3054B oscilloscope.

THPPD031

Measurement of the Residual Resistivity Ratio of the Bus Bars Copper Stabilizer of the 13 kA Circuits of the LHC

quadrupole, dipole, instrumentation, factory

3572

A. Apollonio, S.D. Claudet, M. Koratzinos, R. Schmidt, A.P. Siemko, M. Solfaroli Camillocci, J. Steckert, H. Thiesen, A.P. Verweij
CERN, Geneva, Switzerland

After the incident of September 2008, the operational beam energy of the LHC has been set to 3.5 TeV, since not all joints of the superconducting busbars between magnets have the required quality for 7 TeV operation. This choice is based on simulations to determine the safe current in the main dipole and quadrupole magnets, reproducing the thermal behavior of a quenched superconducting joint by taking into account all relevant factors that affect a possible thermal runaway. One important parameter of the simulation is the RRR (Residual Resistivity Ratio) of the copper stabilizer of the busbar connecting superconducting magnets. A dedicated campaign to measure this quantity for the main 13kA circuits of the LHC on all sectors was performed during the Christmas stop in December 2010 and January 2011. The measurement method as well as the data analysis and results are presented in this paper.

THPPD039

Magnetic Analysis of a Single-Aperture 11T Nb3Sn Demonstrator Dipole for LHC Upgrades

dipole, injection, sextupole, coupling

3596

B. Auchmann, M. Karppinen
CERN, Geneva, Switzerland
V. Kashikhin, A.V. Zlobin
Fermilab, Batavia, USA

Funding: Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
The planned upgrade of the LHC collimation system foresees additional collimators to be installed in the dispersion suppressor areas around points 2, 3, and 7. The necessary longitudinal space for the collimators could be provided by replacing some 8.33-T 15-m-long NbTi LHC main dipoles with shorter 11-T Nb3Sn dipoles compatible with the LHC lattice and main systems. To demonstrate this possibility, in 2011 Fermilab and CERN started a joint R&D program with the goal of building a 5.5-m-long twin-aperture dipole prototype suitable for installation in the LHC by 2014. The first step of this program is the development of a 2-m-long single-aperture demonstration dipole with the nominal field of 11 T at the LHC nominal current of ~11.85 kA and 60-mm bore with ~20% margin. This paper presents the results of magnetic analysis of the single-aperture Nb3Sn demonstrator dipole for the LHC collimation system upgrade.

THPPD040

Quench Protection Analysis of a Single-Aperture 11T Nb3Sn Demonstrator Dipole for LHC Upgrades

dipole, luminosity, quadrupole, status

3599

A.V. Zlobin, I. Novitski, R. Yamada
Fermilab, Batavia, USA

Funding: Work is supported by Fermi Research Alliance, LLC, under contract No. DE-AC02-07CH11359 with the U.S. Department of Energy
The planned upgrade of the LHC collimation system foresees additional collimators to be installed in the dispersion suppressor areas around points 2, 3, and 7. The necessary longitudinal space for the collimators could be provided by replacing some 8.33-T 15-m-long NbTi LHC main dipoles with shorter 11-T Nb3Sn dipoles compatible with the LHC lattice and main systems. To demonstrate this possibility, in 2011 Fermilab and CERN started a joint R&D program with the goal of building by 2014 a 5.5-m-long twin-aperture dipole prototype suitable for installation in the LHC. The first step of this program is the development of a 2-m-long single-aperture demonstration dipole with the nominal field of 11 T at the LHC nominal current of ~11.85 kA and 60-mm bore with ~20% margin. This paper summarizes the results of quench protection analysis of the single-aperture Nb3Sn demonstrator dipole for the LHC collimation system upgrade.

THPPD041

Evaluation and Implementation of High Performance Real-Time Signal Processing For Rayleigh Scattering Based Quench Detection for High Field Superconducting Magnets

solenoid, scattering, LabView, superconducting-magnet

3602

G. Flanagan, R.P. Johnson
Muons, Inc, Batavia, USA
W.K. Chan, J. Schwartz
North Carolina State University, Raleigh, North Carolina, USA
Q. Ruan, D. Schmidt, L. Wenzel, C. Wimmer
National Instruments, Austin, USA

Funding: Supported in part by SBIR Grant 4747 · 11SC06251
YBCO coated conductors are one of the primary options for generating the high magnetic fields needed for future high energy physics devices. Due to slow quench propagation, quench detection remains one of the primary limitations to YBCO magnets. Fiber optic sensing, based upon Rayleigh scattering, has the potential for quench detection with high spatial resolution. This paper discusses the potential of multicore CPU's and FPGA’s to accelerate the signal processing demands associated with Rayleigh scattering based quench detection systems in a real-time environment.

THPPD049

Conceptual Design of a Superconducting Septum for FFAGs

septum, extraction, ion, proton

3620

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
K.J. Peach, T. Yokoi
JAI, Oxford, United Kingdom

Funding: This work was supported by STFC grant ST/G008531/1 and EPSRC Grant EP/E032869/1.
The fixed magnetic field in FFAG (Fixed Field Alternating Gradient) accelerators means that particles can be accelerated very rapidly. This makes them attractive candidates for many applications, for example for accelerating muons for a neutrino factory or for charged particle therapy (CPT). To benefit fully from this the particles have to be extracted at the same rate. In combination with the high magnetic rigidity of the particles this represents a significant challenge, especially where variable energy extraction is required, which implies extraction at variable radius. This paper presents a conceptual design of a 4T superconducting septum for the PAMELA accelerator, which is an FFAG for a combined proton/carbon ion therapy facility. The field in the septum is varied as a function of the horizontal position, which allows variable energy extraction without the need for sweeping of the magnetic field.

THPPD053

Study on Eddy Current Power Losses in Insulated Core Transformer Primary Coil

induction, power-supply, high-voltage, factory

3632

L. Yang, X. Liu, Y.Q. Xiong, J. Yang
Huazhong University of Science and Technology (HUST), Wuhan, People's Republic of China
T. Yu
HUST, Wuhan, People's Republic of China

Insulated core transformer (ICT) high-voltage DC power supply is widely used in electron beam accelerator. With air gap in ICT, the reluctance of magnetic circuit is larger than other transformers, and the transverse magnetic flux leakage around the primary coil is more serious. Because the magnetic flux on the radial direction of coil cannot be ignored, the eddy current loss on the wire should be discussed. In this paper, simulation and analysis of the eddy current loss is presented. The relationship between the sizes of the coil wire is also discussed. An optimal design of the primary coil is shown.

THPPD062

Development of Digital-controlled Corrector Magnet Power Converter with Shunt as a Current Sensing Component

controls, power-supply, feedback

3653

B.S. Wang, J.C. Huang, K.-B. Liu
NSRRC, Hsinchu, Taiwan

In Taiwan light source (TLS), Bira MCOR power converter modules are adopted as the corrector magnet power converters, the output is regulated by analog PWM IC that caused nonlinear behavior at zero cross and the adjustment of compensator for difference kind of magnet load is inconvenient. In the thesis the analog regulation IC is replaced by a fully digital regulation control circuit to realize digital regulation control converter. With plugging the home-made fully DSP regulation control cards into MCOR30 that the current sensing component is a shunt, the switching losses of MOSFET was reduced and the cost that the component of current sense. With the fully digital regulation control circuit, the parameter of the compensator for different magnet load is very easy to adjustment. In addition, the feasibility and validity of MOSFET switching theorem is simulated with Matlab simulink and the performance of this power converter is verified, the output current ripple of this power converter could be lower than 10ppm, which is beyond the requirement of current TLS corrector power converter and qualified to be used in the future TPS facility.

THPPD071

A Compact Switching Power Supply utilizing SiC-JFET for the Digital Accelerator

power-supply, induction, synchrotron, acceleration

3677

K. Okamura, T. Iwashita, K. Takayama, M. Wake
KEK, Ibaraki, Japan
K. Takaki, M. Toshiya
Iwate university, Morioka, Iwate, Japan

New induction synchrotron system using an induction cell has been developed and constructed at KEK*. We refer to the accelerator using the induction acceleration system combined with digitally controlled PWM power supply as Digital Accelerator**. In that system, the switching power supply is one of the key devices which realize digital acceleration. The requirements of the switching power supply are high voltage (2 kV) and high repetition frequency (1 MHz). In the present system, we used series connected MOSFETs as the switching device. However, series connection gives large complexity and less reliability. Among the various switching devices, a SiC-JFET is the promising candidates because it has ultrafast switching speed and voltage blocking capability. Therefore, we have developed a new device to substitute existing silicon MOSFET and succeeded to operate with 1 MHz – 1 kV – 27 A condition***. Then we designed and constructed a ultra compact full bridge switching power supply utilizing those devices as a next step. Design and test results will be presented in the conference.
* T. Iwashita et al., KEK Digital Accelerator, Phys. Rev. ST-AB 14, 071302 (2011)
** K. Takayama et al., in Proc. of IPAC’11, pp 1920-1922
*** K. Okamura et al., in Proc. of IPAC’11, pp 3400-3402

THPPD072

Performance Optimization of the Stacked-Blumlein

coupling, impedance, high-voltage, induction

3680

L.W. Zhang, J. Li, W.D. Wang
CAEP/IFP, Mainyang, Sichuan, People's Republic of China
Y. Li
CAEP, Mainyang, Sichuan, People's Republic of China

Funding: This work was supported by the National Natural Science Foundation of China (11035004)
For the applications of the Dielectric Wall Accelerator (DWA), the stacked Blumlein pulse generator comprised of parallel-plate transmission lines is being developed. The peak output voltage of the stacked Blumlein will be much lower than expected due to the parasitic coupling among the individual pulse forming lines of the Blumlein stack. The finite difference time domain method is used to model the stacked Blumlein structure and determine the outputs. We present the optimization of a 20-Blumleins-stack in this paper. The results for different structures are discussed.

THPPD074

Effect of a Metallized Chamber upon the Field Response of a Kicker Magnet: Simulation Results and Analytical Calculations

kicker, vacuum, ion, booster

3686

M.J. Barnes, M.G. Atanasov, T. Fowler, T. Kramer, T. Stadlbauer
CERN, Geneva, Switzerland

Metallized racetrack vacuum chambers will be used in the pulsed magnets of the Austrian cancer therapy and research facility, MedAustron. It is important that the metallization does not unduly degrade field rise and fall times or the flattop of the field pulse in the pulsed magnets. This was of particular concern for a tune kicker magnet, which has a specified rise and fall time of 100 ns. The impact of the metallization, upon the transient field response, has been determined by finite element method (FEM) simulations: the dependency of the field response to the metallization thickness and resistivity are presented. Formulae for the field response, which permit the use of a ramped transient excitation current, are presented: thus the coating thickness and resistivity can be determined which result in a maximum permissible field attenuation and delay for a given current rise time. In addition, results of simulations of the effect of a magnetic brazing collar, located between the ceramic vacuum chamber and flange, are reported.

THPPD075

Design and Measurements of a Fast High-voltage Pulse Generator for the MedAustron Low Energy Transfer Line Fast Deflector

high-voltage, injection, synchrotron, power-supply

3689

T. Fowler, M.J. Barnes, T. Kramer, F. Müller, T. Stadlbauer
CERN, Geneva, Switzerland

MedAustron, a centre for ion-therapy and research, will comprise an accelerator facility based on a synchrotron for the delivery of protons and light ions for cancer treatment. The Low Energy Beam Transfer line (LEBT) to the synchrotron contains an electrostatic fast deflector (EFE) which, when energized, deviates the continuous beam arriving from the ion source onto a Faraday Cup: the specified voltage is ±3.5 kV. De-energizing the EFE for variable pulse durations from 500 ns up to d.c. allows beam passage for multi-turn injection into the synchrotron. To maintain beam quality in the synchrotron, the EFE pulse generator requires rise and fall times of less than 300 ns between 90 % of peak voltage and a ±1 V level. To achieve this, a pulsed power supply (PKF), with high voltage MOSFET switches connected in a push-pull configuration, will be mounted in close proximity to the deflector itself. A fast, large dynamic range monitoring circuit will verify switching to the ±1 V level and subsequent flat bottom pulse quality. A prototype will be installed in the injector test stand in 2012; this paper presents the design and first measurements of the PKF and its monitoring circuit.

THPPD077

ISIS Injector 2 MW Pulsed RF System Power Supply Upgrade

controls, linac, power-supply, cathode

3695

R.J. Anderson
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
M. Keelan
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

The ISIS pulsed neutron and muon source uses a 4-stage 70 Mev linear accelerator powered by TH116 triode valves. The TH116 anode supply capacitor banks have until recently been supplied by conventional 6-pulse silicon controlled rectifier (SCR) bridges delivering up to 40 kV at 5 A direct current. This dated system has become increasingly difficult to maintain. Early trials of an upgraded system using modern, compact, capacitor charging, switch mode supplies (SMPSs) resulted in severe supply power quality issues due to the pulsed nature of the current demanded from the capacitor banks. Measurements and Spice simulations of the old and replacement supplies allowed the power quality issues to be investigated and an additional external-to-the-SMPS regulator control loop to be developed. The new SMPSs operating with the additional control loop have been tested successfully on several of the linear accelerator stages and are now in continuous operational use. The process of replacing all the original SCR 6-pulse bridges is now well advanced and the operational benefits for ISIS are becoming evident.

THPPD082

A Novel Solid-State Marx Modulator Topology with Voltage Droop Self-Compensation

controls, high-voltage, linac, factory

3707

P. Chen, M. Lundquist, D. Yu
DULY Research Inc., Rancho Palos Verdes, California, USA

Funding: Work supported by U.S. Department of Energy SBIR grant no. DE-FG02-08ER85052.
Solid-state Marx modulators are preferred over conventional modulators in accelerators and radar applications because of their high flexibility, high reliability and long life. However, voltage droop is a notable issue. A novel topology of solid-state Marx modulators is described in this paper for raising their electric energy utilization ratios (EEURs). The new Marx modulator incorporates a buck regulator circuit into each Marx cell and adopts a higher charge voltage than that of application. The topology allows Marx cells to store more electric energy and utilize the energy more efficiently than others. Initial theoretical analysis and preliminary experiments show that solid-state Marx modulators constructed with this topology and under proper control of the stepwise energy release are able to significantly enhance their EEURs. The cost effective Marx modulators with compact energy storage sizes will resolve the issue of voltage droop when they are used in high power, long pulse applications.

THPPP003

Coupling Impedance Study of the New Injection Kicker Magnets of the JPARC Main Ring

impedance, kicker, coupling, vacuum

3725

K. Fan, S. Fukuoka, H. Matsumoto, T. Sugimoto, T. Toyama
KEK, Ibaraki, Japan

New lumped inductance kicker magnets have been developed for the J-PARC main ring injection system. For high intensity beam operation, the beam coupling impedance of the new kickers is a critical issue, which not only generates significant heating inside the ferrite impairing the performance of the kickers, but also drives beam instability. Numerical simulations based on CST studio have been studied during the design stage to optimize the kicker structure. Impedance measurements based on wire method have been carried out. The measured results agree well with the simulation results.

THPPP005

Space Charge Effect in the Presence of x-y Coupling in J-PARC MR

coupling, lattice, space-charge, emittance

3731

K. Ohmi
KEK, Ibaraki, Japan
S. Hatakeyama
JAEA/J-PARC, Tokai-mura, Japan

It is crucial issue to suppress beam loss due to space charge force in J-PARC MR. We focus x-y coupling as a source of the beam loss. x-y coupling is measured by turn-by-turn beam position monitors in J-PARC MR. A space charge simulation under the measured x-y coupling evaluates the beam loss. Tolerance of x-y coupling and how to improve the beam loss are discussed.

THPPP007

Proton-Beam Emittance Growth in SPS Coasts

emittance, cavity, vacuum, proton

3737

R. Calaga, L. Ficcadenti, E. Métral, R. Tomás, J. Tückmantel, F. Zimmermann
CERN, Geneva, Switzerland

Funding: This work partially supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
Proton-beam transverse emittance growth rates have been measured during SPS coasts to assess the possibility of using the SPS as a testbed for the LHC prototype crab cavities. The SPS measurements in coasts were performed at different beam energies, for varying RF voltage, beam intensity, and chromaticity. Results from these measurements are presented with potential explanations for the observed emittance growth.

THPPP015

A Clamped Be Window for the Dump of the HiRadMat Experiment at CERN

vacuum, synchrotron, beam-loading, cavity

3758

M. Delonca, T. Antonakakis, D. Grenier, C. Maglioni, A. Sarrió Martínez
CERN, Geneva, Switzerland

At CERN, the High Radiation to Materials facility (HiRadMat) is designed to test accelerator components under the impact of high-intensity pulsed beams and will start operation in 2012. In this frame a LHC TED -type dump was installed at the end of the line, working in nitrogen over-pressure, and a 258μm-thick beryllium window was placed as barrier between the inside of the dump and the external atmosphere. Because of the special loading conditions, a clamped window design was especially developed, optimized and implemented, the more standard welded window not being suitable for such loads. Considering then the clamping force and the applied differential pressures, the stresses on the window components were carefully evaluated thanks to empirical as well as numerical models, to guarantee the structural integrity of the beryllium foil. This paper reports on choices and optimizations that led to the final design, presenting also comparative results from different solutions and the detailed results for the adopted one.

THPPP022

Coalescing at 8 GeV in the Fermilab Main Injector

LLRF, emittance, synchrotron, space-charge

3779

D.J. Scott, D. Capista, I. Kourbanis, K. Seiya, M.-J. Yang
Fermilab, Batavia, USA

For Project X, it is planned to inject a beam of 3 10¹¹ particles per bunch into the Main Injector. To prepare for this by studying the effects of higher intensity bunches in the Main Injector it is necessary to perform coalescing at 8 GeV. The results of a series of experiments and simulations of 8 GeV coalescing are presented. To increase the coalescing efficiency adiabatic reduction of the 53 MHz RF is required, resulting in ~70% coalescing efficiency of 5 initial bunches. Data using wall current monitors has been taken to compare previous work and new simulations for 53 MHz RF reduction, bunch rotations and coalescing, good agreement between experiment and simulation was found. Possible schemes to increase the coalescing efficiency and generate even higher intensity bunches are discussed. These require improving the timing resolution of the low level RF and/or tuning the adiabatic voltage reduction of the 53 MHz.

THPPP031

RF Design of ESS RFQ

rfq, coupling, cavity, linac

3800

O. Piquet, M. Desmons, A. France
CEA/DSM/IRFU, France
O. Delferrière
CEA/IRFU, Gif-sur-Yvette, France

The low energy front end of ESS is based on a 352 MHz, 5-m long Radiofrequency Quadrupole (RFQ) cavity. It will accelerate and bunch proton beams from 75 keV to 3 MeV. The beam current is 50 mA (75 mA as an upgrade scenario) for 4% duty cycle. A complete RF analysis of the ESS RFQ has been performed using 3D RF simulating codes and a RFQ 4-wire transmission line model. Proposed RFQ is a 4 vane-type structure where 2D cross-section is optimized for lower power dissipation, while featuring simple geometrical shape suitable for easy machining. RF calculations are performed for the whole RFQ, and mainly for the following parts: end cells, vacuum port, tuners and RF coupling ports. Power losses are particularly calculated in order to achieve Thermo-mechanical calculations.

THPPP034

Optimization of a CW RFQ Prototype

rfq, impedance, linac, DTL

3809

U. Bartz, J. Gerbig, H.C. Lenz, A. Schempp
IAP, Frankfurt am Main, Germany

A short RFQ prototype was built for RF-tests of high power RFQ structures. We studied thermal effects to determine critical points of the design. HF-simulations with CST Microwave Studio and measurements were done. The cw-tests with 20 kW/m RF-power and simulations of thermal effects with ALGOR were finished successfully. The optimization of some details of the RF design is on focus now. Results and the status of the project will be presented

THPPP037

Status of the 325 MHz 4-ROD RFQ

rfq, dipole, HOM, linac

3815

B. Koubek, A. Schempp, J.S. Schmidt
IAP, Frankfurt am Main, Germany
L. Groening
GSI, Darmstadt, Germany

For the FAIR project of GSI as part of the proton linac, a 325 MHz 4-ROD RFQ with an output energy of 3 MeV is planned. Due to the simulations regarding the RF design, a prototype of this RFQ was built. Measurements with this prototype to verify the simulation results have been done. In addition, simulations with increasing cell numbers and simulations concerning the boundary fields of the electrodes are presented in this paper.

THPPP038

Simulations of the Influence of 4-Rod RFQ Elements on its Voltage Distribution

rfq, resonance, linac, insertion

3818

J.S. Schmidt, B. Koubek, A. Schempp
IAP, Frankfurt am Main, Germany

The influence of tuning methods and other design elements of 4-rod-RFQs on the voltage distribution have been studied during the last months. Every change in the field geometry or the voltage distribution could for example lead to particle losses or a raise in the surface current on single parts of the RFQ. That’s why further research had to be done about the behavior of the 4-rod-RFQ especially in the comparison of structures at 100 or 200 MHz. The results of an analysis which is concentrated on simulations using CST Microwave Studio to evaluate the effects of the overhang of electrodes, modulation and piston tuners on the fields in the RFQ are presented in this paper.

THPPP039

Simulations for a Buncher-Cavity at GSI

cavity, impedance, resonance, induction

3821

P.L. Till, B. Koubek, A. Schempp, J.S. Schmidt
IAP, Frankfurt am Main, Germany

Buncher cavities can be used to bunch and rebunch or re-accelerate particle beams. A special form of these buncher cavities is a spiral structure. one of its main features is the easy adjustable frequency. A two-gap structure for the GSI has been simulated and will be build at the University of Frankfurt. This structure shall replace an existing buncher at GSI. It is designed to an frequency of 36 MHz. Also general simulations of spiral bunchers will be presented.

THPPP044

RF Set-up Scheme for PEFP DTL

DTL, linac, proton, rfq

3835

J.-H. Jang, Y.-S. Cho, H.S. Kim, H.-J. Kwon
KAERI, Daejon, Republic of Korea

Funding: This work was supported by the Ministry of Education, Science and Technology of the Korean Government.
The proton engineering frontier project (PEFP) is developing a 100-MeV proton linac which consists of a 50 keV injector, a 3-MeV radio frequency quadrupole (RFQ) and a 100-MeV drift tube linac (DTL). The installation of the linac was started in December 2011. The beam commissioning is scheduled for 2012. The phase scan signature method is a common technique to determine the rf set point including the amplitude and phase in DTL tanks. This work summarized the rf set-up scheme for PEFP DTL tanks by using the phase scan signature method.

THPPP046

ESS End-to-End Simulations: a Comparison Between IMPACT and MADX

linac, space-charge, cavity, DTL

3841

E. Laface, R. Miyamoto
ESS, Lund, Sweden
D.C. Plostinar, C.R. Prior
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom

The European Spallation Source will be a 5 MW superconducting proton linac for the production of spallation neutrons. It is composed of an ion source, a radio frequency quadrupole, a drift tube linac and a superconducting linac as well as the low, medium and high, energy beam transport sections. At present these components of the linac are in the design phase: the optimization of the accelerator parameters requires an intensive campaign of simulations to test the model of the machine under possible operational conditions. In this paper the results of simulations performed with the IMPACT and MADX-PTC codes are presented and a comparison is made between them and independent simulations using TraceWin. The dynamics of the beam envelope and single and multi-particle tracking are reported.

THPPP049

Tuning Procedure for the LINAC4 PI Mode Structure (PIMS)

cavity, linac, coupling, electron

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.

THPPP051

Status of the RAL Front End Test Stand

ion, ion-source, rfq, beam-transport

3856

A.P. Letchford, M.A. Clarke-Gayther, D.C. Faircloth, S.R. Lawrie
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
S.M.H. Alsari, M. Aslaninejad, A. Kurup, P. Savage
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
J.J. Back
University of Warwick, Coventry, United Kingdom
G.E. Boorman, A. Bosco
Royal Holloway, University of London, Surrey, United Kingdom
C. Gabor, D.C. Plostinar
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
A. Garbayo
AVS, Eibar, Gipuzkoa, Spain
S. Jolly
UCL, London, United Kingdom
J.K. Pozimski
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

The Front End Test Stand (FETS) under construction at RAL is a demonstrator for front end systems of a future high power proton linac. Possible applications include a linac upgrade for the ISIS spallation neutron source, new future neutron sources, accelerator driven sub-critical systems, a neutrino factory etc. Designed to deliver a 60mA H-minus beam at 3MeV with a 10% duty factor, FETS consists of a high brightness ion source, magnetic low energy beam transport (LEBT), 4-vane 324MHz radio frequency quadrupole, medium energy beam transport (MEBT) containing a high speed beam chopper plus comprehensive diagnostics. This paper describes the current status of the project and future plans.

THPPP052

Modelling the ISIS 70 MeV Linac

DTL, linac, rfq, quadrupole

3859

D.C. Plostinar, C.R. Prior, G.H. Rees
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
A.P. Letchford
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
A.W. Mitchell
University of Warwick, Coventry, United Kingdom

The ISIS linac consists of four DTL tanks that accelerate a 50 pps, 20 mA H⁻ beam up to 70 MeV before injecting it into an 800 MeV synchrotron. Over the last decades, the linac has proved to be a stable and reliable injector for ISIS, which is a significant achievement considering that two of the tanks are nearly 60 years old. At the time the machine was designed, the limited computing power available and the absence of modern modeling codes, made the creation of a complex simulation model almost impossible. However, over the last few years, computer tools have became an integral part of any accelerator design, so in this paper we present a beam dynamics model of the ISIS linac. A comparison between the simulation results and machine operation data will be discussed, as well as possible linac tuning scenarios and recommended upgrades based on the new model.

THPPP053

The Manufacture and Assembly of the FETS RFQ

rfq, alignment, vacuum, controls

3862

P. Savage, J.K. Pozimski
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
A. Garbayo
AVS, Eibar, Gipuzkoa, Spain
A.P. Letchford
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
D.S. Wilsher
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

The Rutherford Appleton Laboratory (RAL) Front End Test Stand (FETS) uses a 324 MHz 4-vane RFQ to accelerate H⁻ ions from 65keV to 3MeV. The RFQ is a copper structure that has been designed as 4 nominally one metre long assemblies. Each assembly consists of 2 major vanes and 2 minor vanes that are bolted together and sealed using an O ring. The mechanical design for the FETS RFQ is complete and the manufacture is underway. In order to achieve the designed physics performance the vanes must be machined and assembled to high degree of accuracy. This requirement has demanded a tight synergy between the design, manufacture and metrology services. Together they have developed detailed procedures for the manufacturing, inspection, alignment and assembly phases. The key points of these procedures will be detailed in this paper.

THPPP063

CW Room Temperature Re-buncher for the Project X Front End

cavity, linac, beam-transport, vacuum

3880

G.V. Romanov, M.H. Awida, M. Chen, I.V. Gonin, S. Kazakov, R.A. Kostin, V.A. Lebedev, N. Solyak, V.P. Yakovlev
Fermilab, Batavia, USA

At Fermilab there is a plan to construct the Project X Injector Experiment (PXIE) facility - a prototype of the front end of the Project X, a multi-MW proton source based on a superconducting linac. The construction and successful operations of this facility will validate the concept for the Project X front end, thereby minimizing the primary technical risk element within the Project. The front end of the linac contains a cw room-temperature MEBT section which comprises an ion source, RFQ, and high-bandwidth bunch selective chopper. The length of the MEBT exceeds 9 m, so three re-bunching cavities are used to support the beam longitudinal dynamics. The paper reports RF design of the re-bunchers along with preliminary beam dynamic and thermal analysis of the cavities.

THPPP064

Project X RFQ EM Design

rfq, quadrupole, dipole, radio-frequency

3883

G.V. Romanov
Fermilab, Batavia, USA
M.D. Hoff, D. Li, J.W. Staples, S.P. Virostek
LBNL, Berkeley, California, USA

Project X is a proposed multi-MW proton facility at Fermi National Accelerator Laboratory (FNAL). The Project X front-end would consist of an H⁻ ion source, a low-energy beam transport (LEBT), a cw 162.5 MHz radio-frequency quadrupole (RFQ) accelerator, and a medium-energy beam transport (MEBT). Lawrence Berkeley National Laboratory (LBNL) and FNAL collaboration is currently developing the designs for various components in the Project X front end. This paper reports the detailed EM design of the cw 162.5 MHz RFQ that provides bunching of the 1-10 mA H⁻ beam with acceleration from 30 keV to 2.1 MeV.

THPPP069

Double-Gap Rebuncher Cavity Design of SNS MEBT

cavity, DTL, linac, impedance

3898

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

A double-gap rebuncher cavity has been studied through design and analysis with computer simulations. This cavity shape is a two cell abridged form of drift tube linac (DTL), instead an omega form of existing single gap elliptical cavity. The cavity operates in TM010 mode, likewise the commonly used single-gap cavities in some medium energy beam transport (MEBT) line of proton accelerators. The new cavity is more power efficient even with slightly lower Q factor because of utilization of two interactive gaps. The breakdown field can be lowered with adjustment of gap and tube length ratio. Electromagnetic, beam envelope, and thermal simulations are presented with comparison to the properties of the conventional elliptical cavity.

THPPP086

UFOs in the LHC: Observations, Studies and Extrapolations

beam-losses, proton, diagnostics, quadrupole

3936

T. Baer, M.J. Barnes, F. Cerutti, A. Ferrari, N. Garrel, B. Goddard, E.B. Holzer, S. Jackson, A. Lechner, V. Mertens, M. Misiowiec, E. Nebot Del Busto, A. Nordt, J.A. Uythoven, V. Vlachoudis, J. Wenninger, C. Zamantzas, F. Zimmermann
CERN, Geneva, Switzerland
T. Baer
University of Hamburg, Hamburg, Germany
N. Fuster Martinez
Valencia University, Atomic Molecular and Nuclear Physics Department, Valencia, Spain

Unidentified falling objects (UFOs) are potentially a major luminosity limitation for nominal LHC operation. They are presumably micrometer sized dust particles which lead to fast beam losses when they interact with the beam. With large-scale increases and optimizations of the beam loss monitor (BLM) thresholds, their impact on LHC availability was mitigated from mid 2011 onwards. For higher beam energy and lower magnet quench limits, the problem is expected to be considerably worse, though. In 2011/12, the diagnostics for UFO events were significantly improved: dedicated experiments and measurements in the LHC and in the laboratory were made and complemented by FLUKA simulations and theoretical studies. The state of knowledge, extrapolations for nominal LHC operation and mitigation strategies are presented.

THPPP088

Beam Loss Studies of the ISIS Synchrotron Using ORBIT

acceleration, injection, synchrotron, emittance

3942

D.J. Adams
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
I.S.K. Gardner, B. Jones, B.G. Pine, A. Seville, H. V. Smith, C.M. Warsop, R.E. Williamson
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom

The ISIS synchrotron forms part of the accelerator chain for the Spallation Neutron Source at RAL, UK. The synchrotron is an 800 MeV, 50Hz , RCS accelerating ~2.8·10¹³ protons per cycle. Beam loss is localized in two super periods of the ring using a system of collimators. The injection and acceleration processes, vacuum vessels and collimation systems have been modeled using the particle tracking code ORBIT. This paper presents simulation results in comparison to measurements of longitudinal profiles and beam loss.

THPPP092

Progress of the Front-End System Development for Project X at LBNL

rfq, ion-source, ion, emittance

3951

D. Li, M.D. Hoff, Q. Ji, A.R. Lambert, T. Schenkel, J.W. Staples, S.P. Virostek
LBNL, Berkeley, California, USA
S. Nagaitsev, L.R. Prost, G.V. Romanov, A.V. Shemyakin
Fermilab, Batavia, USA
C. Zhang
IAP, Frankfurt am Main, Germany

Funding: This work is supported by the Office of Science, United States Department of Energy under DOE contract DE-AC02-05CH11231.
A multi-MW proton facility, Project X has been proposed and is currently under development at Fermilab. Project X is a key accelerator complex for intensity frontier of future high energy physics programs in the US. In collaboration with Fermilab, LBNL takes the responsibility in the development and design studies of the front-end system for Project X. The front-end system would consist of H⁻ ion source(s), low-energy beam transport (LEBT), 162.5 MHz normal conducting CW Radio-Frequency-Quadrupole (RFQ) accelerator, medium-energy beam transport (MEBT), and beam chopper(s). In this paper, we will review and present recent progress of the front-end system studies, which will include the RFQ beam dynamics design, RF structure design, thermal and mechanical analyses and fabrication plan, LEBT simulation studies and concept for LEBT chopper.

THPPP096

Recent Developments and Applications of the Beam Simulation Code Warp

plasma, diagnostics, ion, heavy-ion

3957

J.-L. Vay, P.A. Seidl
LBNL, Berkeley, California, USA
A. Friedman, D.P. Grote
LLNL, Livermore, California, USA

Funding: Supported by US-DOE Contracts DE-AC02-05CH11231 and DE-AC52-07NA27344. Used resources of NERSC, supported by US-DOE Contract DE-AC02-05CH11231.
The Particle-In-Cell Framework Warp is being developed by the Heavy Ion Fusion US program to guide the development of accelerators for high energy density experiments and ultimately for inertial fusion energy. Accurate predictions of the beam phase space are important for understanding the limits to the pulse compression, in particular for NDCX-II now under construction at LBNL. We will present a new numerical method that correct for the effects of linear correlations, offering accurate mapping of energy spread and temperature. The interaction of the beam with the neutralizing plasma can affect non linearly the phase space of the beam. We will present fully kinetic simulation of the beam/plasma interaction aimed toward a better understanding of these effects and possibilities for mitigating or exploiting them. We will also present an application of the original warped coordinate algorithm to the modeling of charge separation in the transition of a 50 MeV singly charged Uranium beam to higher charge state upon passing through a stripping foil, with the goal of decreasing the cost of a Heavy Ion Fusion driver. We also describe studies of beams in plasmas and of injector optimization.
Used resources of NERSC.

THPPR022

Radiation Dose Simulation and Measurement plan for SSRF Beam Lines by Using ATOM Phantoms

photon, neutron, radiation, synchrotron

4008

Y. Sheng, L.X. Liu, X. Xia, J.Q. Xu
SINAP, Shanghai, People's Republic of China

Radiation dose assessment in advanced synchrotron radiation facility is challenging due to the complexity and uncertainties of radiation source terms induced by high energy particle accelerator. Shanghai Synchrotron Radiation Facility, SSRF, is the first third-generation synchrotron facility in China, which was completed in 2009. Radiation dose assessment for workers at SSRF Beam lines is highly concerned. This study presents the dose simulation with Monte Carlo method. The dose simulation was performed with a hybrid phantom coupled into MCNPX code. The hybrid phantom was constructed by combining the ATOM phantom and the Voxel-based Chinese Reference female Phantom, VCRP-woman, originally developed by using the high resolution color photographs. The organs absorbed dose calculated for photon and neutron were compared. An Experiment of measuring the organs dose by using the ATOM phantom will be performed in the near future.

THPPR031

Reliability Modeling Method for Proton Accelerator

cryomodule, linac, proton, target

4035

S. Bhattacharyya, R.K. Yedavalli
Ohio State University, USA
J.S. Kerby, A. Mukherjee
Fermilab, Batavia, USA

Reliability Analysis is an essential part of designing any complex system in order to predict performance and understand availability. However modeling complex systems has been a challenging task due to the large number of components and inter-dependencies. The options have been custom written simulation packages, requiring large investment of programming and debugging time; or standard commercial software running for many days. In our research we developed a hierarchical method to represent the reliability model of “Project X,”* a proposed linear accelerator at Fermi National Accelerator Laboratory. The system is first divided into subsystems small enough to readily simulate. Each subsystem is then separately simulated and parameterized so they can be represented as simple blocks in the top level system diagram. This allows standard, commercial software to model systems with many tens of thousands of components without requiring many days of computer time. Simulation were run and compared with data gathered from existing accelerators.
* S.D. Holmes, "Project X: A Multi-MW Proton Source at Fermilab," Proc. of IPAC’10, TUYRA01, p. 1299 (2010).

THPPR036

Quench Limit Calculations for Steady State Heat Deposits in LHC Inner Triplet Magnets

quadrupole, proton, luminosity, insertion

4050

D. Bocian
IFJ-PAN, Kraków, Poland
F. Cerutti, B. Dehning, A.P. Siemko
CERN, Geneva, Switzerland

In hadron colliders such as the LHC, the energy deposited in the superconductors by the particles lost from the beams or coming from the collision debris may provoke quenches detrimental to the accelerator operation. A Network Model is used to simulate the thermodynamic behavior of the superconducting magnets. In previous papers the validations of network model with measurements performed in the CERN and Fermilab magnet test facilities were presented. This model was subsequently used for thermal analysis of the current LHC inner triplet quadrupole magnets for beam energy of 3.5 TeV and 7 TeV. The detailed study of helium cooling channels efficiency for energy deposits simulated with FLUKA is presented. Some conclusions are drawn on expected inner triplet magnets quench limit.

THPPR037

Estimation of Thresholds for the Signals of the BLMs around the LHC Final Focus Triplet Magnets

proton, radiation, luminosity, beam-losses

4053

M. Sapinski, F. Cerutti, B. Dehning, A. Ferrari, A. Lechner, M. Mauri, A. Mereghetti
CERN, Geneva, Switzerland
C. Hoa
CEA-CENG, Grenoble, France

The Interaction Points of the Large Hadron Collider are the regions where the two circulating beams collide. Hence, the magnets the closest to any Interaction Point are exposed to an elevated radiation field due to the collision debris. In this study the signal in the Beam Loss Monitors due to the debris is estimated and compared with the measurements. In addition, the energy density in the coils and the signal in the Beam Loss Monitors at quench are estimated for various beam loss scenarios. It is shown that the Beam Loss Monitors, as presently installed on the outside of the vacuum vessel of the magnets, cannot disentangle the signals due to a localised halo loss from that of the constant signal due to the collision debris.

THPPR047

Design of Superconducting Rotating-gantry for Heavy-ion Therapy

superconducting-magnet, ion, heavy-ion, optics

4080

Y. Iwata, T. Furukawa, A. I. Itano, K. Mizushima, S. Mori, K. Noda, T. Shirai
NIRS, Chiba-shi, Japan
N. Amemiya
Kyoto University, Kyoto, Japan
T. Fujimoto
AEC, Chiba, Japan
T.F. Fujita
National Institute of Radiological Sciences, Chiba, Japan
T. Obana
NIFS, Gifu, Japan
T. Ogitsu
KEK, Ibaraki, Japan
T. Orikasa, S.T. Takami, S. Takayama, I. Watanabe
Toshiba, Yokohama, Japan

We designed a superconducting rotating-gantry for heavy-ion therapy. This isocentric rotating-gantry can transport heavy ions having 430 MeV/u to the isocenter with irradiation angles between 0-360 degrees, and further has the capability of our fast raster-scanning irradiation, as employed in the existing fixed-irradiation-ports. For the magnets, combined-function superconducting-magnets will be employed. The use of these superconducting magnets allowed us to design the compact gantry, while keeping a sufficient scan size at the isocenter; the length and radius of the gantry would be approximately 13m and 5.5m, respectively, which are comparable to those of the existing proton gantries. Superconducting coils were designed by using the 3D field solver, so as to obtain uniform field distributions. The two superconducting magnets are being constructed. We will present the design of the superconducting gantry as well as details of the superconducting magnets.

THPPR050

Fabrication and High Power RF Test of A C-band 6MeV Standing-wave Linear Accelerating Structure

gun, coupling, electron, 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.

THPPR061

Optimisation Studies of Accelerator Driven Fertile to Fissile Conversion Rates in Thorium Fuel Cycle

proton, neutron, target, scattering

4112

C. Bungau, R.J. Barlow, R. Cywinski
University of Huddersfield, Huddersfield, United Kingdom

The need for proliferation-resistance, longer fuel cycles, higher burn up and improved waste form characteristics has led to a renewed worldwide interest in thorium-based fuels and fuel cycles. In this paper the GEANT4 Monte Carlo code has been used to simulate the Thorium-Uranium fuel cycle. The accelerator driven fertile to fissile conversion rates have been calculated for various geometries. Several new classes have been added by the authors to the GEANT4 simulation code, an extension which allows the state-of-the-art code to be used for the first time for nuclear reactor criticality calculations.

THPPR062

Handling GEM*STER Volatile Radioactive Fission Products

neutron, proton, target, ion

4115

M. Notani, C.M. Ankenbrandt, R.P. Johnson, T.J. Roberts
Muons, Inc, Batavia, USA
C. Bowman
ADNA, Los Alamos, New Mexico, USA

A next-generation advanced technology of nuclear power has been developed for many years. One of the promising future reactor designs with accelerator-produced neutrons is GEM*STAR (Green Energy Multiplier*Subcritical Technology for Alternative Reactors) developed by Accelerator Driven Neutron Application (ADNA), which is a subcritical thermal-spectrum reactor operating with molten salt fuel in a graphite matrix. GEM*STAR is able to use natural uranium as well as unreprocessed spent fuel from light-water reactors (LWR), generating as much electricity as the LWR had generated from the same fuel. Since the advanced design of GEM*STAR is quite different from LWR that uses solid nuclear fuel loaded in the Zircaloy, it requires emission control for volatiles emitted from the molten salt fuel, like as radioactive iodine and cesium. The volatiles caught in the helium gas circulating around the core reactor will be trapped in the cryogenic bottles. Numerical simulations to estimate the amount of fission products were performed for the design of confinement of the volatiles. The result of simulation with spent nuclear fuel from LWR is presented.

THPPR063

1 GeV CW Nonscaling FFAG for ADS, and Magnet Parameters

extraction, lattice, cyclotron, proton

4118

F. Méot, W.-T. Weng
BNL, Upton, Long Island, New York, USA
C. Johnstone
Fermilab, Batavia, USA
P. Snopok
Illinois Institute of Technology, Chicago, IL, USA

Multi-MW proton driver capability remains a challenging, critical technology for many core HEP programs, particularly the neutrino ones such as the Muon Collider and Neutrino factory, and for next generation energy applications such as Accelerator Driven Subcritical Reactors (ADS) and Accelerator Transmutation of Waste for nuclear power and waste management. Work is focused almost exclusively on an SRF linac, as, to date, no re-circulating accelerator can attain the 10^-20 MW capability necessary for the nuclear applications. Recently, the concept of isochronous orbits has been explored and developed for nonscaling FFAGs using powerful new methodologies in FFAG accelerator design. The FFAG can remain isochronous beyond the energy reach of cyclotrons and with fixed magnetic fields and strong focusing coupled to recent advances in tune stability, dynamic aperture, and footprint, serious study is underway on a potential application to the ADS problem. Work is progressing on a stable, high intensity, 0.25-1GeV isochronous FFAG. Development and studies of novel magnets with the nonlinear radial fields required to support isochronous operation are reported here.

THPPR069

Compact, Inexpensive X-Band Linacs as Radioactive Isotope Source Replacements

linac, radiation, electron, 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.

THPPR072

High Power of 10 MeV, 25 kW Electron LINAC for Irradiation Applications

electron, linac, vacuum, 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.

THPPR073

Target Studies for the Production of Lithium 8 for Neutrino Physics Using a Low Energy Cyclotron

target, neutron, proton, cyclotron

4145

A. Bungau, R.J. Barlow
University of Huddersfield, Huddersfield, United Kingdom
J.M. Conrad, J. Spitz
MIT, Cambridge, Massachusetts, USA
M. Shaevitz
Columbia University, New York, USA

Lithium 8 is a short lived beta emitter producing a high energy anti-neutrino, which is very suitable for making several measurements of fundamental quantities. It is proposed to produce Lithium 8 with a commercially available 60 MeV cyclotron using protons or alpha particles on a Beryllium 9 target. We have used the GEANT4 program to model these processes, and calculate the antineutrino fluxes that could be obtained in a practical system. We also calculate the production of undesirable contaminants such as Boron 8, and show that these can be reduced to a very low level.

THPPR074

Simulations of Pion Production in the DAEδALUS Target

proton, target, neutron, hadron

4148

A. Bungau, R.J. Barlow
University of Huddersfield, Huddersfield, United Kingdom
J.M. Conrad, T. Smidt, J. Spitz
MIT, Cambridge, Massachusetts, USA
M. Shaevitz
Columbia University, New York, USA

DAEδALUS, the Decay At-rest Experiment for δCP At the Laboratory for Underground Science will look for evidence of CP-violation in the neutrino sector, which may explain the matter/antimatter asymmetry in our universe. It will make precision measurements of oscillations of anti-muon neutrinos to anti-electron neutrinos using multiple neutrino sources created by low-cost compact cyclotrons. DAEδALUS will utilize a decay-at-rest neutrino beam produced by 800 MeV protons impacting a graphite target. Two well established Monte Carlo codes, MARS and GEANT4, have been used to optimize the design and the performance of the target. A benchmarking of the results obtained with these codes is also presented in this paper.

THPPR076

Optimising Neutron Production From Compact Low Energy Accelerators

target, neutron, proton, cyclotron

4154

N. Ratcliffe, R.J. Barlow, A. Bungau, R. Cywinski
University of Huddersfield, Huddersfield, United Kingdom
T.R. Edgecock
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom

There is currently much development in accelerator based methods to provide flexible and reliable neutron generators, in response to a decline in the availability of nuclear reactors. In this paper the focus is on neutron production via a low energy DC proton accelerator (1-10 MeV) and light target system. GEANT4 simulations are being used to study various aspects of target design, beginning with studies into light targets, such as lithium and beryllium, which are already in use. Initially the aim is to replicate these designs and benchmark these simulations, with other models and experimental results, before investigating how modifications can improve neutron production and tailor experimental geometries to specific applications such as neutron capture therapy and medical isotope production.

FRXAB01

Symplectic Tracking and Compensation of Dynamic Field Integrals in Complex Undulator Structures

undulator, permanent-magnet, polarization, dipole

4165

J. Bahrdt, G. Wüstefeld
HZB, Berlin, Germany

This presentation covers analytical models that describe the interaction of an electron beam with the magnetic field of undulators. Analytic approximations to the Hamilton-Jacobi equation yield generating functions useful for particle tracking and therefore efficient simulation. Analytic expressions for kick maps of APPLE II undulators are presented as well. Passive and active shimming schemes including magic fingers and current sheets are also modeled. Applications at BESSY II are discussed which ensure efficient injection during top-up to satisfy machine protection and radiation safety requirements.

Slides FRXAB01 [1.922 MB]