IPAC2013 - List of Keywords (electron)

Paper	Title	Other Keywords	Page
MOYBB101	Review of Laser Wakefield Accelerators	laser, plasma, injection, wakefield	11
	V. Malka LOA, Palaiseau, France
	Funding: European Research Council for funding the PARIS ERC project (Contract No. 226424). EC FP7 LASERLABEUROPE/ LAPTECH (Contract No. 228334) EuCARD/ANAC, EC FP7 (Contract No. 227579) This review talk will highlight the tremendous evolution of the research on laser wakefield accelerators* that has, in record time, led to the production of high quality electron beams beyond the GeV level, using compact laser systems. I will describe the path we followed to explore different injection schemes (bubble, colliding laser pulses, injection in gradient, longitudinal and transverse, ionisation injection) and I will present the most significant breakthroughs which allowed to generate stable, high peak current and high quality electron beams, with control of the charge, of the relative energy spread and of the electron energy. Modelling and experimental results will be as well reported with examples of applications*. V. Malka, Physics of Plasmas 19, 055501 (2012) ** V. Malka et al., Nature Physics 4, 447 (2008)
	Slides MOYBB101 [14.550 MB]

MOYCB101	Brightness and Coherence of Synchrotron Radiation and FELs	radiation, brightness, FEL, undulator	16
	Z. Huang SLAC, Menlo Park, California, USA
	Essential properties of radiation from storage rings and FELs include spatial- and temporal beam brightness and coherence. Starting from a fundamental representation of the electron beam as a radiating source the electromagnetic power can be represented as modes in phase-space to characterize beam quality. For storage rings, conditions for transverse coherence are possible which can lead to high-resolution imaging under a variety of polarization conditions. For FELs the radiation brightness is over 10 orders of magnitude higher with finite temporal coherence times and much of the total FEL power contained in the dominant mode. This presentation should provide an overview of the above.
	Slides MOYCB101 [9.731 MB]

MOZB102	Undulator Technologies for Future Free Electron Laser Facilities and Storage Rings	undulator, vacuum, radiation, wiggler	26
	M.-E. Couprie SOLEIL, Gif-sur-Yvette, France
	Insertion devices (undulators and wigglers) are key components for high brightness third generation synchrotron sources and for the amplifying medium of free electron lasers. Different technological developments carried out worldwide lead to improved undulator performance. In particular, the advances concerning the in vacuum permanent magnet systems, in particular for short period ones with the operation at cryogenic temperature with NdFeB or PrFeB magnets or for long period ones where in vacuum wigglers will be described. Secondly, progress in Elliptical Polarised Undulators (EPU) will be discussed, such as the DELTA undulator. Recent progress in superconducting undulators will also be reported. Finally, the effect of the insertion devices on the light source operation is analysed, either with the strategies to compensate unwanted effects or in viewing taking advantage of them as for Robinson or damping wigglers for reducing storage ring horizontal emittance.
	Slides MOZB102 [8.940 MB]

MOZB201	Overview of the LHeC Design Study at CERN	lepton, linac, luminosity, proton	40
	O.S. Brüning CERN, Geneva, Switzerland
	The LHeC is a potential future lepton-hadron collider project at CERN based on the existing LHC infrastructure. The presentation highlights the main results of the recently published conceptual design report, including the findings of an international review committee that evaluated it. The presentation outlines the planed future studies and R&D activities for the next years.
	Slides MOZB201 [11.894 MB]

MOPEA004	Beam Lifetime in the ASTRID and ASTRID2 Synchrotron Light Sources: Excitations and Vacuum Dependences	synchrotron, vacuum, ion, emittance	67
	J.S. Nielsen, N. Hertel, S.P. Møller ISA, Aarhus, Denmark
	The beam lifetime is a very important parameter for synchrotron light sources without top-up, and sometimes more important than the lowest possible vertical beam emittance. At the ASTRID synchrotron light source, we have for many years routinely applied a phase modulation of the accelerating RF field, together with a vertical excitation of the beam at the first vertical betatron frequency. These two effects increase the beam lifetime from about 3 hours to more than 100 hours at 150 mA. Lifetime measurements as function of modulation and excitation parameters will be presented. Additionally, measurements of the beam lifetime in ASTRID and ASTRID2 as function of vacuum pressure will be presented.

MOPEA012	Lifetime Studies at Metrology Light Source and ANKA	cavity, optics, scattering, septum	88
	T. Goetsch, J. Feikes, M. Ries, G. Wüstefeld HZB, Berlin, Germany A.-S. Müller KIT, Karlsruhe, Germany
	The Metrology Light Source (MLS), situated in Berlin (Germany) is an electron storage ring operating from 10⁵ MeV to 630 MeV and is serving as the national primary radiation source standard from the near infrared to the vacuum ultraviolet spectral region. In its standard user mode, the lifetime is dominated by the Touschek effect. Measurements and analysis of the Touschek lifetime as a function of beam current and RF-Voltage will be presented and compared to measurements done at the ANKA electron storage ring (Karlsruhe, Germany) which operates at 0.5 to 2.5 GeV. R. Klein et al., Phys. Rev. ST-AB 11, 110701 (2008) ** A.-S. Müller et al., Energy Calibration Of The ANKA Storage Ring, In Proceedings of EPAC 2004

MOPEA013	Radioactive Beam Accumulation for a Storage Ring Experiment with an Internal Target	target, ion, injection, kicker	91
	F. Nolden, C. Dimopoulou, R. Grisenti, C.M. Kleffner, S.A. Litvinov, W. Maier, C. Peschke, P. Petri, U. Popp, M. Steck, H. Weick, D.F.A. Winters, T. Ziglasch GSI, Darmstadt, Germany
	A radioactive ⁵⁶Ni beam was successfully accumulated for an experiment with an internal hydrogen target at the storage ring ESR of GSI, Germany. The radioactive beam was produced and separated at the GSI fragment separator from a stable ⁵⁸Ni beam. About 6·10⁴ ⁵⁶Ni ions were injected into the ESR on a high relative momentum orbit. The beam was subjected to stochastic cooling, bunched and transported to a low relative momentum orbit where it was neither disturbed by the field of the partial aperture injection kicker nor by the fields of the stochastic cooling kickers. Slightly below this deposition momentum, the beam was accumulated and continuously cooled by means of electron cooling. For each experiment with internal hydrogen target, about 80 shots were injected consecutively, leading to a stored beam of roughly 5·10⁶ particles.

MOPEA014	Temporal and Spectral Observation of Laser-induced THz Radiation at DELTA	laser, radiation, storage-ring, simulation	94
	P. Ungelenk, H. Huck, M. Huck, M. Höner, S. Khan, R. Molo, A. Schick DELTA, Dortmund, Germany N. Hiller, V. Judin KIT, Karlsruhe, Germany
	Funding: Work supported by the DFG, the BMBF, the Federal State NRW, the Initiative and Networking Fund of the Helmholtz Association, and the German Federal Ministry of Education and Research. Coherent THz pulses caused by a laser-induced density modulation of the electron bunches are routinely produced and observed at DELTA, a 1.5 GeV synchrotron light source operated by the TU Dortmund University. New measurements performed with a fast hot-electron bolometer allow insight into the turn-by-turn evolution of these pulses. Furthermore, first results from a Fourier transform infrared spectrometer, which is currently under commissioning, are presented.

MOPEA015	A Transverse Electron Target for Heavy Ion Storage Rings	target, ion, interaction-region, storage-ring	97
	S. Geyer, O. Meusel, D. Ries IAP, Frankfurt am Main, Germany O.K. Kester GSI, Darmstadt, Germany
	A transverse electron target is a well suited concept under discussion for storage rings to investigate electron-ion interaction processes relevant for heavy ion accelerators. Using a sheet beam of free electrons in crossed beam geometry promises not only a high energy resolution but also allows access to the interaction region for photon and electron spectroscopy under large solid angles. To realize a compact and multi-purpose applicable design, only electrostatic fields are used for beam focussing. The produced electron beam has a length of 10cm in ion beam direction and a width of around 5mm in the interaction region with densities of ~10⁹electrons/cm³. The target geometry allows the independent adjustment of the electron beam current and energy in the region of several 10eV and a few keV. The setup meets the high requirements for an operation in the UHV environment of a storage ring and is installed applying the so-called animated beam technique. The electron target is dedicated to the FAIR storage rings. First measurements have been performed at a test bench. An overview of the project status will be presented including first results of the characterization measurements.

MOPEA017	Electron Cooling of Heavy Ions Interacting with Internal Target at HESR of FAIR	target, emittance, ion, scattering	103
	T. Katayama, M. Steck GSI, Darmstadt, Germany R. Maier, D. Prasuhn, H. Stockhorst FZJ, Jülich, Germany
	The High Energy Storage Ring (HESR) is designed and optimized to accumulate and store the anti-proton beam for the internal target experiment. The recent demand of atomic physics has impacted to use the HESR facility also as the storage ring of bare heavy ions. In this concept the bare heavy ions are injected at 740 MeV/u from the Collector Ring where the ions are well stochastically cooled to be matched with HESR ring acceptance. In the HESR the 2 MeV electron cooler is prepared with the maximal electron current of 3 A and the cooling length of 2.7 m. The electron cooling process of typically ²³⁸U⁹²⁺ beam is simulated for the Hydogen and Xe internal target with simultaneous use of barrier voltage to compensate the mean energy loss caused by the interaction with internal target. In the present report the detailed simulation results of 6D phase space obtained by the particle tracking code are precisely discussed.

MOPEA020	Comparison of Different Approaches to Determine the Bursting Threshold at ANKA	radiation, synchrotron, storage-ring, synchrotron-radiation	112
	P. Schönfeldt, N. Hiller, V. Judin, A.-S. Müller, M. Schwarz, J.L. Steinmann KIT, Karlsruhe, Germany
	The synchrotron light source ANKA at the Karlsruhe Institute of Technology provides a dedicated low-α-optics. In this mode bursting of Coherent Synchrotron Radiation (CSR) is observed for bunch charges above a threshold that depends on beam parameters. This threshold can be determined by several approaches, e.g. bunch lengthening or changes in the THz radiation spectra. This paper compares different methods and their implementation at the ANKA storage ring outlining their advantages, disadvantages and limitations, including reliability and possibility of real time analysis.

MOPEA021	Status of the HESR Electron Cooler Test Set-up	simulation, cathode, controls, vacuum	115
	M.W. Bruker, K. Aulenbacher, J. Dietrich, S. Friederich, A. Hofmann, T. Weilbach HIM, Mainz, Germany K. Aulenbacher IKP, Mainz, Germany
	For the proposed High Energy Storage Ring (HESR) at FAIR, it is foreseen to install an electron cooling device with a beam current of 3 A and a beam energy of 8 MeV. A test set-up was built at Helmholtz-Insitut Mainz (HIM) to conduct a feasibility study. One of the main goals of the test set-up is to evaluate the gun design proposed by TSL (Uppsala) with respect to vacuum handling, EM fields and the resulting beam parameters. Another purpose of the set-up is to achieve an energy recuperation efficiency of 1 - 10^-5. To measure this quantity, a Wien filter has to be employed, which will also prove capable of mitigating collection losses. The current status of the project will be presented.

MOPEA022	Beam Profile Measurement for High Intensity Electron Beams	laser, scattering, photon, diagnostics	118
	T. Weilbach, K. Aulenbacher, M.W. Bruker HIM, Mainz, Germany K. Aulenbacher IKP, Mainz, Germany
	Recent developments in the field of high intensity electron beams in the regime below 10 MeV, e.g. energy recovery linacs or magnetized high energy electron coolers, have led to special demands on the beam diagnostics. Since commonly used diagnostic tools like synchrotron radiation and scintillation screens are ineffective or not able to withstand the beam power without being damaged, new methods are needed. Hence a beam profile measurement system based on beam induced fluorescence (BIF) was built. This quite simple system images the light generated by the interaction of the beam with the residual gas onto a PMT. A more elaborated system, the Thomson Laser Scanner (TLS) - the non-relativistic version of the Laser Wire Scanner - is proposed as a method for non-invasive measurement of all phase space components, especially in the injector and merger parts of an ERL. Both methods are implemented in a 100 keV photo gun. Beam profile measurements with BIF as well as first results of the TLS will be presented.

MOPEA026	X-ray Powder Diffraction Beamline for the Iranian Light Source Facility	photon, synchrotron, focusing, brilliance	130
	H. Khosroabadi, S. Amiri, H. Ghasem, A. Gholampour ILSF, Tehran, Iran H. Ghasem IPM, Tehran, Iran
	Iranian Light Source Facility (ILSF) project has been initiated since 2010 in order to design and construction of a synchrotron facility in Iran. In parallel with the machine’s activities, scientific committee, users community and beamline technical group are working on different aspects of the scientific and beamline design issues for the operating phase after construction. X-ray powder diffraction beamline is one of the most priorities in ILSF due to wide range of applications and big potential user community in Iran. Conceptual design report of this beamline operating in other worldwide synchrotrons have been studied and compared in details. The light source and schematic design of the beamline has been prepared in this study. Then, the parameters have been calculated and have been optimized by employing computational software such as XOP and SHADOW. The optical properties of the optical elements such as reflectivity, absorbance, Bragg diffraction, rocking curve, aberration, etc have been studied at this design, and the results have been compared with the other published results. The outcome and final results of this design progress will be discussed in details. References: Conceptual Design Report (2011, summer), ILSF, http://ilsf.ipm.ac.ir/. ** http://www.esrf.eu/UsersAndScience/Experiments/TBS/SciSoft/xop2.3.

MOPEA038	Coherent Wiggler Radiation of Picosecond CW Electron Beam Produced by DC-SRF Photoinjector	wiggler, radiation, SRF, acceleration	160
	S. Huang, J.E. Chen, S. Chen, K.X. Liu, S.W. Quan, Zh.W. Wang, X.D. Wen, F. Zhu PKU, Beijing, People's Republic of China
	The DC-SRF photoinjector at Peking University is capable of providing CW electron beam with the energy of 3-5 MeV. The beam has high repetition rate, picosecond bunch length and high quality, which can be used to produce high repetition rate THz wave by wiggler radiation. Through off-crest acceleration, electron beam from the injector may be bunched, which will lead to coherent enhancement of the radiation power. With current setup of the DC-SRF injector and a 10-period wiggler, THz radiation power of 10s mW to a few watts can be achieved within the wavelength range of 200 μm to 500 μm. In this work, we will present the calculation results about THz radiation produced by the electron beam from DC-SRF photoinjector. The preparation for the experiments will be also described.

MOPEA040	Study of Geometry Dependent Multipacting of a Superconducting QWR	accelerating-gradient, simulation, cavity, vacuum	166
	K. Zhou, X.Y. Lu, X. Luo, S.W. Quan, L. Yang, Z.Y. Yao PKU, Beijing, People's Republic of China
	Funding: The Major Research Plan of National Natural Science Foundation of China A superconducting quarter wave resonator (QWR) of frequency=162.5 MHz and β=0.085 has been designed at Peking University. This paper focus on the multipacting (MP) study for the QWR with CST Particle Studio. The simulation results for the initial designed model reveal that there is no sign of MP with its normal operating accelerating gradients in the range of 6-8 MV/m. The accelerating gradient range that may incur MP is from about 1.4 MV/m to 3.2 MV/m, and the places where MP may be encountered are mainly located at the top part of the QWR. So the effect of different top geometries on MP has also been studied in depth. Our results show that inward convex round roof is better than other round roofs, and plane roofs have an obvious advantage over round roofs on the suppression of MP in general. While considering the optimization of its electromagnetic (EM) design, our initial designed model is also acceptable.

MOPEA043	Transverse Instabilities of Two Twisted Beams in a Storage Ring	ion, storage-ring, simulation, kicker	172
	B.C. Jiang, M.Z. Zhang, Z.T. Zhao SINAP, Shanghai, People's Republic of China G.X. Xia UMAN, Manchester, United Kingdom
	Two twisted beams (two beams run on the different closed orbit) in a storage ring which is produced by fast kickers can potentially deliver two bunds of radiations through one insertion device or one bend magnet, in this way doubles the beam line stations. This operation mode needs higher beam current and more RF buckets to be filled to keep the brightness comparable to the single beam operation mode. The resistive wall instability and ion trapping effects is analysed to address the higher current operation possibility. The analyze results show that twisted beams can weaken those two instabilities.

MOPEA056	Measuring and Improving the Momentum Acceptance and Horizontal Acceptance at MAX III	cavity, lattice, vacuum, storage-ring	205
	A. Hansson, Å. Andersson, J. Breunlin, G. Skripka, E.J. Wallén MAX-lab, Lund, Sweden
	Lifetime measurements for varying horizontal scraper positions performed at different RF frequencies suggested a horizontal aperture restriction in the MAX III synchrotron light source. A combination of local orbit distortions and horizontal scraper measurements pinpointed the location of the horizontal aperture restriction to the center of the main cavity straight section. The aperture restriction was determined to be located 10.4 ± 0.3 mm from the beam center. The precise result was achieved by measurements and calculations of the Touschek lifetime as a function of the main cavity voltage. Realignment of the main cavity increased the average lattice momentum acceptance from 0.0116 ± 0.0003 to 0.0158 ± 0.0003 and the horizontal acceptance from 26 ± 2 × 10^-6 m to larger than 44 ± 2 × 10^-6 m. The increase in momentum acceptance increased the lifetime in MAX III by a factor of two.

MOPEA057	Studies of the Electron Beam Lifetime at MAX III	scattering, cavity, vacuum, emittance	208
	A. Hansson, Å. Andersson, J. Breunlin, G. Skripka, E.J. Wallén MAX-lab, Lund, Sweden
	MAX III is a 700 MeV 3rd generation synchrotron light source located at the MAX IV Laboratory in Sweden. The lifetime in the storage ring is lower than originally envisaged. From vertical scraper measurements the lifetime contributions at 300 mA stored current have been determined. The lifetime is mainly limited by the Touschek lifetime, which is lower than its design value, whereas the vacuum lifetime is close to the expected value. The low Touschek lifetime is explained by a lower than design emittance ratio and momentum acceptance in the storage ring.

MOPEA063	The First Results of the NESTOR Commissioning	injection, storage-ring, dipole, focusing	225
	A.Y. Zelinsky, V.P. Androsov, O. Bezditko, V.N. Boriskin, P. Gladkikh, A.N. Gordienko, V.A. Grevtsev, A. Gvozd, V.E. Ivashchenko, A.A. Kalamayko, I.I. Karnaukhov, I.M. Karnaukhov, D. Korzhov, V.P. Kozin, V.A. Kushnir, V.P. Lyashchenko, M.P. Maksim, V.S. Margin, N.I. Mocheshnikov, V.V. Mytrochenko, A. Mytsykov, F.A. Peev, O.V. Ryezayev, V.P. Sergienko, A.A. Shcherbakov, S. Sheyko, V.L. Skirda, Y.N. Telegin, V.I. Trotsenko, O.P. Zolochevskij, O.D. Zvonarjova NSC/KIPT, Kharkov, Ukraine
	In the paper the first results of the NESTOR facility are presented. 60 MeV electron linac injector has been tested and the first electron beam with project parameters was registered at the screen monitors. Electron beam was passed through the transportation channel and injection system. As a result, the first turn of the storage ring was closed.

MOPEA065	Commissioning of the Ion Source for Siemens Novel Electrostatic Accelerator	ion, plasma, ion-source, extraction	231
	H. von Jagwitz-Biegnitz JAI, Oxford, United Kingdom P. Beasley, O. Heid Siemens AG, Erlangen, Germany D.C. Faircloth STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom A.J. Holmes Marcham Scientific Ltd, Hungerford, United Kingdom R.G. Selway Inspired Engineering Ltd, Climping, United Kingdom B. Singh, E. Zitvogel BNL, Upton, New York, USA
	Siemens is developing a novel compact DC electrostatic tandem accelerator and currently building a prototype. A dedicated H⁻ ion source for this accelerator has been designed and built. This paper reports on some of the design features as well as results of the commissioning phase of this filament driven DC multicusp volume H⁻ ion source. Stable H⁻ currents of more then 300 μA at 10 keV have been extracted. This satisfies the beam current requirement of the novel accelerator.

MOPEA070	Operating the Diamond Light Source in Low Alpha Mode for Users	injection, lattice, factory, optics	246
	I.P.S. Martin, R. Bartolini, G. Cinque, G. Rehm, C.A. Thomas Diamond, Oxfordshire, United Kingdom R. Bartolini JAI, Oxford, United Kingdom
	Since its first introduction in April 2009, the low alpha operational mode has been continually refined in order to best meet the needs of the user community. Initially the optics were used only to generate short x-ray pulses, for which a stable, low emittance, single bunch was requested, with the emphasis placed on increased bunch charge over shortest absolute pulse duration. More recently, the optics have been adapted to enhance the CSR gain in the THz region of the electromagnetic spectrum. In this paper we summarise the work carried out in order to meet these two demands.

MOPEA077	Accelerator Physics and Light Source Research Program at Duke University	FEL, wiggler, storage-ring, feedback	264
	Y.K. Wu FEL/Duke University, Durham, North Carolina, USA
	Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033. he accelerator physics and light source research program at Duke Free-Electron Laser Laboratory (DFELL), TUNL, is focused on the development of the storage ring based free-electron lasers (FELs), and a state-of-the-art Compton gamma-ray source, the High Intensity Gamma-ray Source (HIGS). Driven by the storage ring FEL, the HIGS is world's most intense Compton gamma-ray source with a maximum total flux of few 10¹⁰ gamma per second (around 10 MeV). Operated in the energy range from 1 to 100 MeV, the HIGS is a premier nuclear physics research facility in the world. In 2012, we completed a major accelerator upgrade project with a wiggler switchyard system which allows the configuration changes between planar and helical FEL wigglers, and a great enhancement of the FEL gain when operated with 3 or 4 helical wigglers. In this paper, we will describe our ongoing light source development to produce gamma-ray beams in the new energy range of 100 and 158 MeV. We will also provide a summary of our accelerator physics research activities in the area of nonlinear dynamics, beam instability research, and FEL research.

MOPEA083	Energy Modulation in Coherent Electron Cooling	ion, plasma, FEL, simulation	276
	G. Wang, M. Blaskiewicz, V. Litvinenko BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. Coherent electron cooling (CeC) relies on Debye shielding to imprint information of the ion beam to an electron beam [1]. Apart from the density modulation, Debye shielding also modulates the energy of electrons, which provides additional seeding for the free electron laser (FEL) amplifier. In this work, we show that the energy modulation of a longitudinal slice of the electrons, induced by dynamic Debye shielding of a moving ion in anisotropic electron plasma with κ-2 velocity distribution, can be expressed into a 1D integral. The results are then applied to the 1D FEL model to investigate the effects of energy modulation to the correcting force in the kicker. [1] V.N. Litvinenko, Y.S. Derbenev, Coherent Electron Cooling, Physical Review Letters, 102 (2009) 114801. http://link.aps.org/abstract/PRL/v102/e114801

MOPFI001	Characterization of a Superconducting Pb Photocathode in a SRF Gun Cavity	cathode, laser, gun, cavity	279
	R. Barday, T. Kamps, O. Kugeler, A. Neumann, M. Schmeißer, J. Völker HZB, Berlin, Germany P. Kneisel JLAB, Newport News, Virginia, USA R. Nietubyć NCBJ, Świerk/Otwock, Poland J.K. Sekutowicz DESY, Hamburg, Germany J. Smedley BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Bundesministerium für Bildung und Forschung and Land Berlin. The Pb deposition activity is supported by EuCARD. Photocathodes are a limiting factor for the next generation of ultra-high brightness photoinjector driven accelerators. We studied the behavior of a superconducting Pb cathode in the cryogenic environment of a superconducting rf gun cavity related to the quantum efficiency, its spatial distribution and the work function. Cathode surface contaminations can modify the performance of the photocathodes as well as the gun cavity. We discuss the possibilities to remove these contaminations.

MOPFI005	XPS and UHV-AFM Analysis of the K2CsSb Photocathodes Growth	cathode, vacuum, background, factory	291
	S.G. Schubert HZB, Berlin, Germany I. Ben-Zvi, M. Ruiz-Osés Stony Brook University, Stony Brook, USA X. Liang SBU, Stony Brook, New York, USA H.A. Padmore, T. Vecchione LBNL, Berkeley, California, USA T. Rao, J. Smedley BNL, Upton, Long Island, New York, USA
	Funding: This work is funded by the Department of Energy, under Contract No. KC0407-ALSJNT-I0013, DE-SC0005713, the Bundesministerium für Bildung und Forschung (BMBF) and the state of Berlin, Germany. Next generation light sources, based on Energy Recovery Linac and Free Electron Laser technology will rely on photoinjector based electron sources. Successful operation of such sources requires reliable photocathodes with long operational life, uniform and high quantum efficiency, low thermal emittance and low dark current. The goal of this project is to construct a cathode which meets these requirements. Advances in photocathode research must take a combined effort. The materials have to be analyzed by means of chemical composition, surface structure and these findings have to be correlated to the quantum efficiency and performance in the injector. The presented work focuses on the chemical composition and surface structure of K2CsSb photocathodes. The XPS and AFM measurements were performed at the Center of Functional Nanomaterials at BNL. K2CsSb photocathodes were grown under UHV conditions. The components were adsorbed one at a time and after each growth step the corresponding XPS spectra was taken. During growth the quantum efficiency was recorded. As last step the sample was moved into the AFM without exposure to air to determine the surface roughness.

MOPFI006	A New Load Lock System for the Source of Polarised Electrons at ELSA	polarization, vacuum, laser, ion	294
	D. Heiliger, W. Hillert, B. Neff ELSA, Bonn, Germany
	Funding: supported by DFG (SFB/TR16) The inverted source of polarized electrons at the electron stretcher accelerator ELSA routinely provides a pulsed beam with a current of 100 mA and a polarization degree of about 80%. One micro-second long pulses with 100 nC charge are produced by irradiating a GaAs strained-layer superlattice photocathode (8 mm in diameter) with laser light. Future accelerator operation requires a significantly higher beam intensity, which can be achieved by using photocathodes with sufficiently high quantum efficiency. Therefore, and in order to enhance the reliability and uptime of the source, a new extreme high-vacuum (XHV) load lock system was installed and commissioned. It consists of a loading chamber in which an atomic hydrogen source is used to remove any remaining surface oxidation, an activation chamber for heat cleaning of the photocathodes and activation with cesium and oxygen and a storage chamber in which up to five different types of photocathodes with various diameters of the emitting surface can be stored under XHV conditions. Additionally, tests of the photocathodes' properties can be performed during accelerator operation.

MOPFI011	Construction and First Tests of the New Injection System for the Linac II at DESY	linac, gun, injection, positron	303
	C. Liebig, M. Hüning, M. Schmitz DESY, Hamburg, Germany
	For the Linac II, which supplies the accelerator chain at DESY with electrons and positrons, a new injection system is planned. It is supposed to ensure reliable operation and to avoid the beam loss of about 60% at energies up to 400 MeV and the associated activation. The function of the injector components, the entire injection system and the acceleration in the linac sections were optimized in simulations. The main components are a 6 A/100 kV triode gun, buncher and a dispersive section for energy collimation. The output energy is 5 MeV and the beam pulse length can be chosen from 5 ns to 50 ns. The new buncher structure is a hybrid of a standing wave and traveling wave structure and allows a compact design and good electron capture. One of two assembled structures has been tuned and completed a test rig in the linac tunnel. In this test system detailed analysis of its properties is in progress as well as minor corrections like alignment and improvements of reliability. The final installation is going to take place from September 2013. First experimental analysis compared to simulation results will be presented.

MOPFI012	Measurement of Adsorption Rates of Residual Gases for NEA-GaAs Surface	cathode, ion, vacuum, emittance	306
	M. Kuriki, H. Iijima, K. Miyoshi, K.U. Uchida HU/AdSM, Higashi-Hiroshima, Japan
	A GaAs photocathode activated the surface to negative-electron-affinity (NEA) is an important device for high-average-current electron accelerators such as a next-generation light source based on an energy recovery linac. The NEA surface is normally formed by a yo-yo technique in which cesium and oxygen are applied onto the surface alternately. Although the initial quantum efficiency is relatively larger than that of another cathode, the lifetime is shorter. The degradation with time elapsing even if the electron beam is not extracted is mainly caused by adsorption of residual gases in a vacuum chamber. We have evaluated the adsorption rates of various gases for the NEA surface by measuring the dark lifetime in sample gases such as hydrogen, carbon oxide and carbon dioxide.

MOPFI013	A Lifetime Study of CsK2Sb Cathode	cathode, laser, vacuum, brightness	309
	M. Kuriki, H. Iijima, K. Miyoshi, N. Norihito HU/AdSM, Higashi-Hiroshima, Japan
	Funding: Cooperative and Supporting Program for Researches and Educations in　Universities by High energy accelerator research organization (KEK) CsK2Sb multi-alkali cathode is one of the candidates of robust and high efficiency cathode for high brightness electron source. CsKSb can be driven by green laser and it is a big advantage comparing to Cs2Te cathode which is widely used as a robust photo-cathode and driven by UV light. In Hiroshima University, a test chamber for CsK2Sb photo-cathode study is developed. In the chamber, CsK2Sb photo-cathode is formed by evaporation on SUS base plate. During the evaporation, amount is monitored by quartz meter. We devised good locations of the evaporation source, base plate, and thickness monitor, so that all evaporation processes for Cs, K, and Sb are under control. The base plate temperature is also controlled during the cathode formation. More than 2.0% quantum efficiency was achieved at the first activation test. The cathode lifetime was more than 200 hours and more than 20C in charge. The latest experimental result will be reported.

MOPFI014	A Charge Lifetime Study of NEA GaAs Cathode by Ion Back-bombardment	cathode, ion, vacuum, simulation	312
	M. Kuriki KEK, Ibaraki, Japan L. Guo, H. Iijima, K. Miyoshi HU/AdSM, Higashi-Hiroshima, Japan
	Funding: Quantum beam project by the Ministry of Education, Culture, Sports, Science and Technology; The title is High Brightness Photon Beam by Laser-Compton Scattering. NEA GaAs cathode is one of the most important techniques for advanced future projects based on linac. Up to 90% polarized beam can be generated with high quantum efficiency, 0.1 – 10%. The extremely low emittance beam can be generated driven by optimized wavelength laser. Although these remarkable features, the less robustness has been the biggest issue on the real operation of this cathode. According to past experiments, there are three sources of the cathode degradation; gas absorption, thermal desorption, and ion-back bombardment. First two processes could be controlled by less vacuum pressure in order of 10^-10Pa and keeping the cathode temperature low. The ion back-bombardment is the last issue which should be solved for high brightness operation in such as ERL. We observed the cathode quantum efficiency evolution in various laser power density and bias voltage. We found that the cathode degradation was due to the ion back-bombardment quantitatively and the deactivation coefficient of NEA surface by one ion collision did not depend on the bias voltage. We report the experimental results and its analysis based on the ion back-bombardment hypothesis.

MOPFI017	SuperKEKB Positron Source Target Protection Scheme	target, positron, radiation, simulation	315
	L. Zang, T. Kamitani KEK, Ibaraki, Japan
	The SuperKEKB requires an intense beam with a large number of positrons, which is generated by a high energy electron beam strike on a solid tungsten target. The cascade shower in the target deposits large amount of energy in the material leading to target damage. The pulsed electron beam distributed the energy non-uniformly over the target. In that case, a mechanical stress appears due to the large thermal gradient during each pulse, which could potentially destroy the target. Based on the analysis of the SLAC damaged target, peak energy deposition density (PEDD) should not exceed 35 J/g to ensure a long term of safe operation. One way of reducing PEDD is increasing the beam spot size. Hence we proposed a target protection scheme, in which a protection target is placed upstream of generation target as a spoiler. The aim is to maintain the generation target’s PEDD below 35 J/g even with a point primary electron beam. In this paper, we will introduce graphite, aluminum and copper as the protection target material candidates. And also present the PEDD and positron yield evaluation as a function of various parameters such as protection target thickness and drift space.

MOPFI019	Beam Generation from a 500 kV DC Photoemission Electron Gun	gun, cathode, laser, high-voltage	321
	N. Nishimori, R. Hajima, S.M. Matsuba, R. Nagai JAEA, Ibaraki-ken, Japan Y. Honda, T. Miyajima, M. Yamamoto KEK, Ibaraki, Japan H. Iijima, M. Kuriki HU/AdSM, Higashi-Hiroshima, Japan M. Kuwahara Nagoya University, Nagoya, Japan
	Funding: This work is supported by MEXT Quantum Beam Technology Program and partially supported by JSPS Grants-in-Aid for Scientific Research in Japan (23540353). The next generation light source such as X-ray FEL oscillator requires high brightness electron gun with megahertz repetition rate. We have developed a DC photoemission electron gun at JAEA for the compact energy recovery linac (cERL) light source under construction at KEK. This DC gun employs a segmented insulator with guard rings to protect the insulator from field emission generated from central stem electrode. We have successfully applied 500-kV on the ceramics with a cathode electrode in place and generated beam from the 500kV DC photoemission gun in October 2012. Details of the beam generation test will be presented.

MOPFI020	Cold Test of the Coaxial Cavity for Thermionic Triode Type RF Gun	cavity, gun, resonance, FEL	324
	T. Konstantin, Y.W. Choi, T. Kii, R. Kinjo, K. Masuda, M. Mishima, K. Nagasaki, H. Negm, H. Ohgaki, K. Okumura, M. Omer, S. Shibata, K. Shimahashi, K. Yoshida, H. Zen Kyoto University, Institute for Advanced Energy, Kyoto, Japan
	A thermionic rf gun has several advantages as compared to photocathode gun. Such as low cost, high averaged current and simple operation. However a thermionic rf gun has a significant disadvantage in form of back bombardment effect. The KU-FEL facility is an oscillator type FEL, which uses a thermionic 4.5 cell S-band RF gun for electron beam generation. The back bombardment effect causes increasing current in macropulse, which limits the gain of the FEL. In order to mitigate the current increase we plan to modify thermionic rf gun to triode type rf gun. Therefore an additional rf cavity has been designed. This cavity has separate rf power supply with amplitude and phase control. By this means we can properly adjust the injection of electrons into the main gun body. According to simulations the triode type gun can reduce 80% of back streaming electron energy. The cold tests of the first prototype have revealed deviation from designed values. Based on the tests of the first prototype new prototype with integrated mechanism for resonance tuning has been designed and fabricated. In this work we report the cold test of the redesigned prototype of the coaxial rf cavity. K. Masuda et al. Proceedings of FEL 2006, BESSY Berlin. ** M. Takasaki et al. Proceedings of FEL 2010, Malbö

MOPFI023	Development of Better Quantum Efficiency and Long Lifetime Iridium Cerium Photocathode for High Charge electron RF Gun	laser, cathode, gun, linac	327
	D. Satoh TIT, Tokyo, Japan N. Hayashizaki RLNR, Tokyo, Japan M. Yoshida KEK, Ibaraki, Japan
	We developed an Ir5Ce photocathode as a high charge electron source for SuperKEKB electron linac. The required electron beam parameters are 5 nC and 10 mm•mrad from the electron gun of the SuperKEKB electron linac. We plan to generate this electron beam using a laser-driven RF gun installed with a photocathode that has a long lifetime and a high-power laser system through more than a year without replacement. Therefore, we focused on the Ir5Ce compound as a new photocathode which has a high melting point (> 2100 K) and a low work function (2.57 eV). The results of measurements showed that the quantum efficiency of Ir5Ce photocathode was 1.0×10^-4 treated by the laser cleaning using the 4nd harmonic of Nd:YAG laser or the heater treatment. Furthermore, its photoemission properties could be maintained for a long term even if its photocathode was in the low vacuum conditions ( ～10^-6 Pa) since the Ir5Ce compound is far less contaminated than other photocathodes. Finally, We have succeed to generate electron beams of 4.4 nC by the Ir5Ce photocathode installed at the 3-2 sector DAW type RF gun and accelerate it through a linac end in KEK electron linac.

MOPFI024	Ultra-short Electron Bunch Generation by an ECC RF Gun	gun, radiation, laser, cathode	330
	Y. Koshiba, T. Aoki, M. Mizugaki, K. Sakaue, M. Washio Waseda University, Tokyo, Japan T. Takatomi, J. Urakawa KEK, Ibaraki, Japan
	Funding: Work supported by JSPS Grant-in-Aid for Young Scientists (B) 23740203 and Scientific Research (A) 10001690 Energy Chirping Cell attached rf gun (ECC rf gun) is a photocathode rf gun specialized for ultra-short bunch generation. This ECC rf gun has been made with the collaboration of High Energy Accelerator Research Organization (KEK). Although the bunch length could be controlled by the laser pulse width, the bunch length ends up to be more than 1ps due to space charge effect when using a femto-second laser and a normal 1.6 cell cavity. Concerning this phenomenon, ECC is attached right after the 1.6 cell so that the electron bunch would be compressed after the electron bunch is accelerated around 5MeV. The roll of ECC is to chirp the energy with the linear part of the rf electric field. The electron bunch would be compressed by velocity difference as it drifts. Simulation results from PARMELA and GPT show that ECC rf gun can accelerate an 100pC bunch with the bunch length less than 100fs. We already manufactured this ECC rf gun and installed in our system. We demonstrated the ultra-short bunch by measuring the coherent THz light by synchrotron radiation and transition radiation. In this conference, we will report the results of ultra-short bunch generation experiments, and future plans.

MOPFI031	Progress on the Construction of the 100 MeV / 100 kW Electron Linac for the NSC KIPT Neutron Source	linac, neutron, controls, dipole	351
	Y.L. Chi, J. Cao, P. Chen, B. Deng, C.D. Deng, D.Y. He, X. He, M. Hou, X.C. Kong, Q. Le, X.P. Li, J. Liu, R.L. Liu, W.B. Liu, H.Z. Ma, G. Pei, S. Pei, H. Song, L. Wang, S.H. Wang, X. Wang, Q. Yang, J. Yue, J.B. Zhao, J.X. Zhao, Z.S. Zhou IHEP, Beijing, People's Republic of China M.I. Ayzatskiy, I.M. Karnaukhov, V.A. Kushnir, V.V. Mytrochenko, A.Y. Zelinsky NSC/KIPT, Kharkov, Ukraine Y. Gohar ANL, Argonne, USA
	IHEP, China is constructing a 100 MeV / 100 kW electron linac for NSC KIPT, Ukraine. This linac will be used as the driver of a neutron source based on a subcritical assembly. In 2012, the injector part of the linac was pre-installed as a testing facility in the experimental hall #2 of IHEP. The injector beam and key hardware testing results were satisfying. Recently, the injector testing facility was disassembled and all of the components for the whole linac have been shipped to Ukraine from China by ocean shipping. The installation of the whole machine in KIPT will be started in June. The progress on the construction are reported, injector beam and key hardware testing results are presented.

MOPFI032	Electron Emission of the Stripping Foil and Collimation System for CSNS/RCS	proton, collimation, scattering, injection	354
	M.Y. Huang, Y.D. Liu, N. Wang, S. Wang IHEP, Beijing, People's Republic of China
	For the Rapid Cycling Synchrotron of the China Spallation Neutron Source (CSNS/RCS), the electron emission plays an important role in the accelerator limitation. The interactions between the proton beam and the stripping foil were studied, and the electron scattering processes were simulated by the ORBIT and FLUKA codes. Then, the electron energy distribution and the electron yielding rate can be given. Furthermore, the interactions between the proton beam and the collimation system were studied, and the electron scattering processes were simulated. Then, the energy distribution of the primary electron emission can be given and the yielding rate of the primary electron can be obtained.

MOPFI034	First Intense H⁻ Beam Generated by a Microwave-driven Pure Volume Source	ion, ion-source, plasma, extraction	360
	S.X. Peng, J. Chen, J.E. Chen, Z.Y. Guo, H.T. Ren, Zh.W. Wang, Y. Xu, T. Zhang PKU, Beijing, People's Republic of China A.L. Zhang Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China J. Zhao State Key Laboratory of Nuclear Physics and Technology, Beijing, Haidian District, People's Republic of China
	The 2.45 GHz Electron cyclotron resonance (ECR) plasma generators have demonstrated their efficiency, reproducibility on producing H⁺, D⁺, O+, N+, He+, Ar+* and He2+ at Peking University(PKU). Recently, modifications on magnet field configuration, discharge chamber structure and extraction system have been done to set-up a microwave-driven pure volume H⁻ ion source. First experiment was done on PKU ion source test bench at the beginning of Nov, 2012. A 15 mA H⁻ ion beam has been produced at 40 keV by this prototype source. This paper describes the source principle and design in detail and reports on the current status of the development work. * H. T. Ren, S. X. Peng*, P. N. Lu, S. Yan, Q. F. Zhou, J. Zhao, Z. X. Yuan, Z. Y. Guo and J. E. Chen, Rev. Sci. Instrum. 83, 02B905 (2012)

MOPFI036	Study of the Cold Cathode RF Electron Gun Based on Doped Diamond Films at CAEP	gun, cathode, FEL, emittance	366
	X. Li TUB, Beijing, People's Republic of China W. Bai, M. Li CAEP/IAE, Mianyang, Sichuan, People's Republic of China
	Diamond relevant materials have been considered as a promising field emission cathode in recent years. High current density can be obtained either by diamond field emission arrays or by doped diamond films under electrical strengths of several decades of MV/m. Based on the doped films a half cell S-band electron gun has been designed and constructed at CAEP. The gun can provide an accelerating gradient of 60-80 MV/m on the cathode surface (6 mm in diameter). Simulations have proven good performance of such a gun but it needs confirmed by further experiments. Details of the experiments and comparisons with simulations will be reported.

MOPFI037	Design and Experiment of a Compact C-band Photocathode RF Gun for UED	gun, solenoid, emittance, cathode	369
	X.H. Liu, H.B. Chen, W.-H. Huang, C.-X. Tang, Z. Zhang TUB, Beijing, People's Republic of China
	A compact C-band photocathode RF gun for the MeV UED facility is developed in Tsinghua University, which is designed to work at the frequency of 5.712GHz. This paper presents the physics and RF structure design, and beam dynamics optimization of this C-band RF gun. Some new structure design will be adopted in this gun, including the optimized cavity length and elliptical iris, which is helpful to achieve lower emittance and larger mode separation. This paper likewise presents experiment parameters and the cold test results of this C-band RF gun.

MOPFI038	Generation and Measurement of Sub-picosecond Electron Bunch in Photocathode RF Gun	laser, radiation, emittance, acceleration	372
	W.W. Li, Z.G. He, R. Huang, Q.K. Jia, G. Zhou USTC/NSRL, Hefei, Anhui, People's Republic of China
	The generation of subpicosecond electron bunch in the photocathode rf gun was considered and simulated by improving the acceleration gradient of the gun, suitably tuning the charge of the electron bunch and the acceleration phase. To measure the length of the electron bunch, the design of a nondestructive bunch length measurement technology was also presented in this paper.

MOPFI039	The Design of a Compact THz Source Based on Photocathode RF Gun	radiation, gun, emittance, space-charge	375
	W.W. Li, Z.G. He, R. Huang, Q.K. Jia USTC/NSRL, Hefei, Anhui, People's Republic of China
	Narrow-band THz coherent Cherenkov radiation can be driven by a subpicosecond electron bunch traveling along the axis of a hollow cylindrical dielectric-lined waveguide. We present a scheme of compact THz radiation source based on the photocathode rf gun. On the basis of our analytic result, the subpicosecond electron bunch with high charge (800pC) can be generated directly in the photocathode rf gun. A narrow emission spectrum peaked at 0.24 THz with 2 megawatt (MW) peak power is expected to gain in the proposed scheme (the length of the facility is about 1.2 m), according to the analytical and simulated results.

MOPFI044	VHF Gun Research at SINAP	gun, cavity, FEL, vacuum	380
	Q. Gu, L. Chen, W. Fang, G.Q. Lin SINAP, Shanghai, People's Republic of China
	The R&D work on the high power THz based on energy recovery linac (ERL) has been carried out in Shanghai Institute of Applied Physics (SINAP). One of the key components for the ERL is the high brightness electron source. The low frequency gun technology has been adopted, by comparing with the SRF gun and DC gun. In this paper, the design and cold test of a 250MHz gun will be presented.

MOPFI045	Studying of Multipacting in Micro-pulse Electron Gun	gun, simulation, resonance, cavity	383
	L. Liao, W. Fang, Q. Gu, M. Zhang, M.H. Zhao SINAP, Shanghai, People's Republic of China
	Depending on the complexity of multipacting phenomenon, more works are focused on the occurrence of multipacting in the micro-pulse electron gun. In this paper, the multipacting resonance condition is determined in a reentrant cavity model of the gun. The resonance parameters work as the input for VORPAL simulations in order to achieve a steady state saturation in the cavity. The simulation results showed that the gun can give rise to electrons beam with high currents and short pulses.

MOPFI057	Studies for the LHeC Beam Transfer Systems	linac, kicker, injection, extraction	410
	C. Bracco, B. Goddard CERN, Geneva, Switzerland
	The LHeC would allow for collisions between an electron beam from a new accelerator with the existing LHC hadron beam. Two possible configurations were studied: a separate LINAC (LINAC-ring) or a new electron ring superimposed on the LHC (ring-ring). The racetrack LINAC is now considered as the baseline for the LHeC design, with the ring-ring solution a back up. The studies performed for all the considered options are presented in this paper. For the LINAC-ring option the requirements for the post-collision line and the beam dump design have been evaluated in the cases of a 140 GeV and a 60 GeV electron beam. In the ring-ring option studies have been performed of the optics design of the transfer line from the a 10 GeV injector LINAC into the LHeC ring and of the injection system. The internal 60 GeV electron ring dump design has also been considered.

MOPFI058	Studies of Cs3Sb Cathodes for the CLIC Drive Beam Photoinjector Option	cathode, gun, laser, vacuum	413
	I. Martini, E. Chevallay, S. Döbert, V. Fedosseev, C. Heßler, M. Martyanov CERN, Geneva, Switzerland
	Within the CLIC (Compact Linear Collider) project, feasibility studies of a photoinjector option for the drive beam as an alternative to its baseline design using a thermionic electron gun are on-going. This R&D program covers both the laser and the photocathode side. Whereas the available laser pulse energy in ultra-violet (UV) is currently limited by the optical defects in the 4th harmonics frequency conversion crystal induced by the 0.14 ms long pulse trains, recent measurements of Cs3Sb photocathodes sensitive to green light showed their potential to overcome this limitation. Moreover, using visible laser beams leads to better stability of produced electron bunches and one can take advantages of the availability of higher quality optics. The studied Cs3Sb photocathodes have been produced in the CERN photoemission laboratory using the co-deposition technique and tested in a DC gun set-up. The analysis of data acquired during the cathode production process will be presented in this paper, as well as the results of life-time measurements in the DC gun.

MOPFI065	VELA (formerly EBTF) Simulations and First Beam Commissioning	gun, diagnostics, simulation, laser	431
	J.W. McKenzie, D. Angal-Kalinin, J.K. Jones, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	VELA (Versatile Electron Linear Accelerator), formerly known as EBTF (Electron Beam Test Facility), at STFC Daresbury Laboratory, is a photoinjector test facility which will provide beam into two user areas for scientific and industrial applications. It is based on a 2.5 cell S-band RF photoinjector driven by a Ti:Sapphire laser. The design is aimed to deliver short bunches at 10-250 pC charge with low transverse emittance. We present beam dynamics simulations of VELA as well as the results from first beam commissioning.

MOPFI066	An Ultra-Low Energy Electron Beam Ion Trap in Shanghai	ion, plasma, injection, cathode	434
	J. Xiao, R. Hutton, X. Jin, D. Lu, B. Tu, Y. Yang, R. Zhao, Y. Zou Fudan University, Shanghai, People's Republic of China
	Electron beam ion traps (EBITs) are very useful tools for disentanglement studies of atomic processes in plasmas. In this paper, a new ultra-low energy EBIT, SH-HtscEBIT, is reported. This EBIT can operate in the electron energy range of 30–4000 eV, with a current density of up to 100 A/cm². The low energy limit of this machine is 30 eV, which is the lowest energy among the EBITs around the world. The maximum magnetic field in the central drift tube region of this EBIT is around 0.25 T, produced by a pair of high temperature superconductor coils. This EBIT is set up for the purpose of disentangling spectroscopic studies of edge plasmas relevant to magnetic fusion devices, and of astro-plasmas. All the elements for the spectroscopic studies can be injected through an injection system. Both the design and the performance of this EBIT are presented.

MOPFI068	High Repetition Rate Highly Stable S-band Photocathode Gun for the CLARA Project	gun, cavity, laser, cathode	437
	B.L. Militsyn, L.S. Cowie, P. Goudket, S.P. Jamison, J.W. McKenzie, K.J. Middleman, R. Valizadeh, A.E. Wheelhouse STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom V.V. Paramonov RAS/INR, Moscow, Russia M.D. Roper STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	Compact Linear Accelerator for Research and Applications (CLARA) is a 250 MeV electron facility which is under development at STFC ASTeC. The CLARA photo-injector is based on a RF photocathode gun operating with metal photocathodes and driven by a third harmonic of Ti: Sapphire laser (266 nm). The injector will be operated with laser pulses with an energy of up to 2 mJ, pulse durations down to 180 fs FWHM and a repetition rate of up to 400 Hz. In order to investigate performance of different photocathodes the gun is equipped with a load-lock system which would allow replacement of the photocathodes. Duration and emittance of electron bunches essentially depends on the mode of operation and vary from 0.1 ps at 20 pC to 5 ps at 200 pC and from 0.2 to 2 mm mrad respectively. Requirements for the stability of beam arrival time at the CLARA experimental area are extremely high and vary from hundreds down to tenths femtoseconds. In the presented article we analyse stability of the guns with 1.5 and 2.5 cell and the beam quality delivered by a gun with coaxial and waveguide coupler and analyse possibility of injection time stabilisation with low level RF and optical feedback system.

MOPFI069	Preparation of the Polycrystalline Copper Photocathodes for the VELA RF Photocathode Gun	plasma, gun, ion, cathode	440
	R. Valizadeh, A.N. Hannah, K.J. Middleman, B.L. Militsyn, T.C.Q. Noakes, R.N.C. Santer STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom M.D. Roper STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	The Electron Beam Test Facility (EBTF) is a high performance electron source under commissioning at ASTeC. The photoinjector of the source is based on a S-band photocathode RF gun operating with a copper photocathode which is driven by a third harmonic of Ti: Sapphire laser (266 nm). The photocathode used in the RF gun is an integrated part of the gun cavity which is polycrystalline copper disk, polished to 1um roughness, and is placed at the back wall of the first 0.5 cell in the gun cavity. In order to accomplish a procedure to activate surface prior installation, copper test samples with roughness of 0.1 um were prepared by different techniques. The best results have been obtained by ex-situ plasma cleaning in an oxygen atmosphere. Analyses showed that there was no carbon on the surface and the surface was composed of copper oxide. After heating the sample in-situ to 220 C for almost all the surface oxide was removed. For this surface a QE of 2 x10^-5 was measured. Further heating to higher temperature did not result in any improvement either in surface composition nor a noticeable increase in QE. Prepared such a way operational photocathode is now under commissioning in the gun.

MOPFI071	High Power Cyclotrons for the Neutrino Experiments DAEδALUS and IsoDAR	cyclotron, ion, proton, ion-source	446
	R.J. Barlow, A. Bungau, A.M. Kolano University of Huddersfield, Huddersfield, United Kingdom A. Adelmann PSI, Villigen PSI, Switzerland J.R. Alonso LBNL, Berkeley, California, USA W.A. Barletta, A. Calanna, D. Campo, J.M. Conrad MIT, Cambridge, Massachusetts, USA L. Calabretta INFN/LNS, Catania, Italy F. Méot BNL, Upton, Long Island, New York, USA H.L. Owen UMAN, Manchester, United Kingdom M. Shaevitz Columbia University, New York, USA
	DAEδALUS (Decay At rest Experiment for δ_cp At a Laboratory for Underground Science) has been proposed to measure the value of the CP violating phase delta through the oscillation of low energy muon anti-neutrinos to electron antineutrinos. With a single large detector, three accelerators at different distances enable the oscillation to be measured with sufficient accuracy. We have proposed the superconducting multi-megawatt DAEδALUS Supercinducting Ring Cyclotron (DSRC) as the means of producing the 800 MeV 12 mA protons required, through the acceleration of H₂⁺, ions with highly efficient stripping extraction. The DSRC comprises twin ion sources and injector cyclotrons, followed by a booster. The injector cyclotron can also be used for a separate experiment, IsoDAR (Isotope Decay At Rest) in which low energy protons produce Lithium 8, and thus a very pure electron antineutrino source which can be used to measure, or rule out, short range oscillation to a sterile neutrino. We describe recent developments in the designs of the injector and the booster, and the prospects for the two experiments.

MOPFI074	Ultracold and High Brightness Electron Source for Next Generation Particle Accelerators	laser, plasma, brightness, emittance	452
	G.X. Xia, R. Appleby, W. Bertsche, M.A. Harvey UMAN, Manchester, United Kingdom S. Chattopadhyay STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom S. Chattopadhyay Cockcroft Institute, Warrington, Cheshire, United Kingdom A.J. Murray The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
	The ultra-cold plasma-based electron source has recently been proposed as an alternative to the conventional photoemitters or thermionic electron guns, which are widely used in today’s particle accelerators. The advantages of the ultra-cold plasma-based electron source lie in the fact that the electron beam extracted from the cold plasma (from ionization of cold atoms) has very low electron temperature, e.g. down to 10 K, and has the potential for producing high brightness and ultra-short electron bunches. All these features are crucial for the next generation particle accelerators, e.g. free electron lasers, plasma-based accelerators and the future linear colliders. In this paper, we will introduce our proposed facility on cold electron source based at Photon Science Institute (PSI) in the University of Manchester.

MOPFI078	The Possibility of Generation of High Energy Electron Beam at the SNS Facility	acceleration, laser, linac, solenoid	458
	T.V. Gorlov, A.V. Aleksandrov, V.V. Danilov ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725 The linac of the SNS accelerator facility can be used to produce an electron beam with 300-400 MeV energy. At present there are a few predesigned experiments with electron beam that can be alternatively carried out at the SNS. However, the SNS linac is designed and optimized for acceleration of H⁻ , which brings some problems when considering direct acceleration of electrons. Alternative machine setup for electron acceleration and transport are discussed. Here, we present a study of the optimal electron beam parameters that can be achieved without any significant changes of the SNS accelerator.

MOPFI082	Redesign and Development of the Shanghai Electron Beam Ion Trap	ion, vacuum, alignment, cryogenics	467
	D. Lu, Y. Shen, Z. Shi, J. Xiao, Y. Yang, Y. Zou Fudan University, Shanghai, People's Republic of China
	Over the last few years the Shanghai Electron Beam Ion Trap (EBIT) has been successfully redesigned and rebuilt. The original machine, developed under collaboration with the Shanghai Institute of Nuclear and Applied Physics, first generated an electron beam in 2005. Shanghai EBIT could be operated with electron beam energies between 1 and 130 keV and currents up to 160 mAmps. After several years of operation, it was found that some improvements/modifications to the old design were necessary. This contribution will discuss several of the main aspects of the redesigned Shanghai EBIT. So far it has been operated up to an electron energy of 40 keV with an current density of over 2400 A per square cm. The new EBIT is made primarily from Titanium instead of Stainless Steel and has an order of magnitude better background vacuum, a more efficient and economical cryogenic system, and also excellent optical alignment. Finally the magnetic field in the central drift tube region can reach up till 4.8 T.

MOPME003	Development of Diamond Sensors for Beam Halo and Compton Spectrum Diagnostics After The Interaction Point of ATF2	collimation, simulation, photon, vacuum	470
	S. Liu, P. Bambade LAL, Orsay, France S. Bai IHEP, Beijing, People's Republic of China T. Tauchi, N. Terunuma KEK, Ibaraki, Japan
	ATF2 is a low energy (1.3GeV) prototype of the final focus system for ILC and CLIC linear collider projects. A major issue at ATF2 and in linear colliders is to control the beam halo, which consists of tails extending far beyond the Gaussian core of the beam. At present there is no dedicated collimation for the beam halo at ATF2, and the transverse distribution near the interaction point is not well known. The development of a sensor based on CVD diamond to scan the beam halo in the vacuum chamber a few meters after the interaction point is presented. This system also aims to detect the Compton recoil electrons generated by the laser interferometer (Shintake monitor) used to measure the beam size at the interaction point of ATF2.

MOPME004	Fast Luminosity Monitoring using Diamond Sensors for Super Flavour Factories	luminosity, scattering, photon, positron	473
	C. Rimbault, P. Bambade LAL, Orsay, France
	Super flavour factories aim to reach very high luminosities thanks to a new concept whereby the ultra-low emittance beams collide with a large crossing angle. Fast luminosity measurements are needed as input to luminosity optimization and feedback in the presence of dynamic imperfections. The required small relative precision can be reached exploiting the very large cross section of the radiative Bhabha process at zero photon scattering angle. The instrumental technique selected to sustain the large particle fluxes is based on diamond sensors to be positioned via moveable stages immediately outside the beam pipe, at locations chosen to minimize the contamination from other particle loss mechanisms.

MOPME005	Goubau Line and Beam Characterization of TURBO-ICT for SwissFEL	instrumentation, FEL, resonance, laser	476
	S. Artinian, J.F. Bergoz, F. Stulle BERGOZ Instrumentation, Saint Genis Pouilly, France P. Pollet, V. Schlott PSI, Villigen PSI, Switzerland
	SwissFEL will be able to operate with electron bunch doublets 28ns apart. Each of the bunches carries 10pC to 200pC of charge with bunch lengths of a few femto-seconds. For charge calibration of the FEL photon pulses, a measurement accuracy of 1% is desired. The Turbo-ICT accomplishes these requirements with negligible beam position and bunch length dependence. It is insensitive to dark current and features high immunity to background noise. We characterize the Turbo-ICT performance on a Goubau line, also known as single-wire transmission line. The Goubau line utilizes electromagnetic fields with frequencies up to many GHz. It allows accurate bench testing including beam position and bunch length dependence. The results are compared to beam measurements performed at the SwissFEL Injector Test Facility (SITF).

MOPME006	The New Orbit Correction System at ELSA	polarization, closed-orbit, acceleration, extraction	479
	J.-P. Thiry, A. Balling, A. Dieckmann, F. Frommberger, W. Hillert ELSA, Bonn, Germany
	ELSA is a fast ramping stretcher ring currently supplying polarized electrons with energies up to 2.4 GeV. To preserve the degree of polarization, the vertical orbit needs to be continuously corrected during beam acceleration. The acceleration is usually performed within 300 ms, with a maximum ramping speed of 6 GeV/s. We aim to achieve a vertical rms deviation not exceeding 50 μm all along the fast energy ramp. In the near future we plan to accelerate polarized electrons up to 3.2 GeV. Therefore, both the power supplies and the corrector magnets have been currently upgraded: first, new power supplies working with a pulsed transistor H-Bridge were developed and successfully installed. Additionally, the existing vertical corrector magnets will now be replaced by newly developed ones. In our contribution, we will present the new correction hardware supplemented by the beam position monitors and their readout electronics.

MOPME007	High Resolution Synchrotron Light Analysis at ELSA	synchrotron, diagnostics, vacuum, optics	482
	S. Zander, F. Frommberger, P. Hänisch, W. Hillert, M.T. Switka ELSA, Bonn, Germany
	Funding: Funded by the DFG within the SFB/ TR 16 The Electron Stretcher Facility ELSA provides polarized electrons with energies up to 3.5 GeV for external hadron experiments. In order to suffice the need of stored beam intensities towards 200 mA, advanced beam instability studies need to be carried out. An external diagnostic beamline for synchrotron light analysis has been set up and provides the space for multiple diagnostic tools including a streak camera with time resolution of < 1 ps. Beam profile measurements are expected to identify instabilities and reveal their thresholds. The effect of adequate countermeasures is subject to analysis. The current status of the beamline development will be presented.

MOPME008	Beam Diagnostics by Using Bunch-by-bunch Feedback Systems at the DELTA Storage Ring	feedback, injection, kicker, laser	485
	M. Höner, H. Huck, M. Huck, S. Khan, R. Molo, A. Schick, P. Ungelenk DELTA, Dortmund, Germany
	Funding: Work supported by BMBF (05K10PEB) At DELTA, a 1.5-GeV electron storage ring operated by the TU Dortmund University, longitudinal and transverse bunch-by-bunch feedback systems are in use to detect and suppress multi-bunch instabilities. Besides that, the digital feedback systems are excellent diagnostics tools. As an example, by exciting a certain number of bunches within the bunch train, the coupling to the non-excited bunches can be investigated below and above the instability threshold. Other examples include studies of the injection process and monitoring bunch oscillations during sudden beam loss. First experimental results will be presented in this paper.

MOPME010	Transverse Beam Profile Diagnostics using Point Spread Function Dominated Imaging with Dedicated De-focusing	radiation, target, background, focusing	488
	G. Kube, S. Bajt DESY, Hamburg, Germany W. Lauth IKP, Mainz, Germany Yu.A. Popov, A. Potylitsyn, L.G. Sukhikh TPU, Tomsk, Russia
	Transverse beam profile diagnostics in electron accelerators is usually based on direct imaging of a beam spot via optical radiation (transition or synchrotron radiation). In this case the fundamental resolution limit is determined by radiation diffraction in the optical system. A method to achieve resolutions beyond the diffraction limit is to perform point spread function (PSF) dominated imaging, i.e. the recorded image is dominated by the resolution function of a point source (single electron), and with knowledge of the PSF the true image (beam spot) may be reconstructed. To overcome the limited dynamical range of PSF dominated imaging, a dedicated de-focusing of the optical system can be introduced. In order to verify the applicability of this method, a proof-of-principle experiment has been performed at the Mainz Microtron MAMI (University of Mainz, Germany) using optical transition radiation. Status and results of this experiment will be presented.

MOPME011	Investigation of the Applicability of Parametric X-ray Radiation for Transverse Beam Profile Diagnostics	radiation, photon, diagnostics, background	491
	G. Kube, C. Behrens DESY, Hamburg, Germany A.S. Gogolev, Yu.A. Popov, A. Potylitsyn TPU, Tomsk, Russia W. Lauth IKP, Mainz, Germany S. Weisse DESY Zeuthen, Zeuthen, Germany
	Transverse beam profile diagnostics in electron linacs is widely based on optical transition radiation (OTR) as standard technique which is observed in backward direction when a charged particle beam crosses the boundary between two media with different dielectric properties. The experience from modern linac based light sources like LCLS or FLASH shows that OTR diagnostics might fail because of coherence effects in the OTR emission process. A possibility to overcome this limitation is to measure at much shorter wavelengths, i.e. in the X-ray region, using parametric X-ray radiation (PXR) which additionally offers the advantage to be generated at crystal planes oriented under a certain angle to the crystal surface, thus allowing a spatial separation from a possible COTR background . A first test experiment has been performed at the Mainz Microtron MAMI (University of Mainz, Germany) in order to study the applicability of PXR for beam diagnostics, and the status of this experiment will be presented. A. Gogolev, A. Potylitsyn, G. Kube, Journal of Physics 357 (2012) 012018

MOPME012	Single-bunch Longitudinal Phase Space Diagnostics in Multi-bunch Mode at the European XFEL	septum, simulation, dipole, diagnostics	494
	M. Yan, C. Gerth DESY, Hamburg, Germany
	Dedicated longitudinal electron beam diagnostics is highly demanded for the control and optimization of modern X-ray free-electron lasers (XFEL). At the European XFEL, 3 transverse deflecting structures (TDS) will be installed at different locations of the accelerator for measurements of slice emittance and longitudinal profile. Operation of a TDS in combined use with an energy spectrometer, e.g. a dispersive section after a single dipole magnet, allows additionally for longitudinal phase space (LPS) measurements. However, utilization of a dipole magnet is not compatible with single-bunch measurements in multi-bunch operation mode, which will be the standard operation mode of the European XFEL. In this paper, we propose a LPS diagnostic beamline consisting of a TDS, fast kicker and septum magnet for the European XFEL. The layout of the accelerator lattice with optimized optics for LPS measurements will be presented.

MOPME014	Electro-optical Bunch Length Measurements at the ANKA Storage Ring	laser, wakefield, storage-ring, background	500
	N. Hiller, A. Borysenko, E. Hertle, E. Huttel, V. Judin, B. Kehrer, S. Marsching, A.-S. Müller, M.J. Nasse, A. Plech, M. Schuh, S.N. Smale KIT, Karlsruhe, Germany P. Peier, V. Schlott PSI, Villigen PSI, Switzerland B. Steffen DESY, Hamburg, Germany
	Funding: Supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320 and by the German Federal Ministry of Education and Research under contract number 05K10VKC A setup for near-field electro-optical bunch length measurements has recently been installed into the UHV system of the ANKA storage ring. For electro-optical bunch length measurements during ANKA's low alpha operation, a laser pulse is used to probe the field induced birefringence in an electro-optical crystal (GaP in our case). The setup allows for both electro-optical sampling (EOS, multi-shot) and spectral decoding (EOSD, single- and multi-shot) measurements. This paper presents first results and discusses challenges of this method employed for the first time at a storage ring.

MOPME021	Ionization Profile Monitor (IPM) of J-PARC 3-GeV RCS	ion, injection, acceleration, vacuum	515
	H. Harada, K. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan S. Kato Tohoku University, Graduate School of Science, Sendai, Japan
	Ionization profile monitors (IPM) were installed in the 3-GeV RCS ring of J-PARC and used to observe the beam-profile for the transverse plane in beam commissioning. These electrodes and MCPs of IPMs were upgraded in 2012 summer shutdown in order to improve the external electric field for leading the electrons and ions to MCPs. This presentation will be described the results of observed beam profile in beam commissioning and be discussed the new issues for the ion and electron collection mode.

MOPME027	Bunch Length Measurement of 181 MeV Beam in J-PARC Linac	linac, target, vacuum, simulation	532
	A. Miura, H. Oguri, N. Ouchi, J. Tamura JAEA/J-PARC, Tokai-mura, Japan A. Feschenko, A.N. Mirzojan RAS/INR, Moscow, Russia K. Futatsukawa, T. Miyao KEK, Ibaraki, Japan M. Ikegami J-PARC, KEK & JAEA, Ibaraki-ken, Japan T. Maruta KEK/JAEA, Ibaraki-Ken, Japan
	In J-PARC Linac, an energy and intensity upgrade project has started since 2009 using Annular Coupled Structure (ACS) cavities. Because the longitudinal matching before ACS cavities is additionally required, we decided to employ the bunch shape monitors (BSMs) to measure the longitudinal beam profile. After three years from the start of BSM project, three BSMs were fabricated. All three BSMs were installed during the summer shutdown of 2012. We tried to measure the longitudinal beam profile exited from SDTL cavities. In this paper, we introduce the outline of BSM project, the first data acquisition and related small problems.

MOPME028	A Preliminary Study of the Vibration Wire Monitor for Beam Halo Diagnostic in J-PARC L3BT	diagnostics, proton, injection, linac	535
	K. Okabe, M. Kinsho, K. Yamamoto, M. Yoshimoto JAEA/J-PARC, Tokai-mura, Japan
	In the J-PARC 3-GeV Rapid Cycle Synchrotron (RCS), transverse beam halo diagnostic and scraping are required to increase the output beam power. Wire scanners and halo scrapers were used for measurement of projected beam distributions to determine the extent of beam halo formation at Linac-3GeV Beam Transport line (L3BT). In order to determine more detail of halo formation, Vibration Wire Monitor (VWM) was installed in L3BT for the beam halo measurement and the offline study at the test stand with low energy electron gun are started. The high sensitivity of the VWM makes it a prospective one for investigation of beam halo and weak beam scanning. In this paper, we will report a preliminary results of offline studies and beam halo measurement by VWM at L3BT.

MOPME031	Emittance Measurement with Multi-wire Scanners for BEPC-II Linac	emittance, positron, linac, injection	541
	H. Geng, W.B. Liu, W. Qiao, Q. Qin, Y.F. Sui, Y. Yue IHEP, Beijing, People's Republic of China
	During the BEPC-II linac upgrade, five wire scanners have been installed in the common transport line, which makes a fast emittance measurement possible. In this paper, we will show the primary results of BEPC-II linac emittance measurement using multi-wire scanner method. The least squares method will be used for data analysis. A comparison of the results with the ones obtained by quad scan method will also be given.

MOPME036	Prototype Experiment Preparation of a 54.167MHz Laser Wire System for FEL-THz Facility at CAEP	laser, photon, FEL, cathode	550
	D. Wu TUB, Beijing, People's Republic of China W. Bai, M. Li, H. Wang, J. Wang, X. Yang CAEP/IAE, Mianyang, Sichuan, People's Republic of China
	In this paper, a prototype experiment preparation of a 54.167 MHz laser wire system is presented, which will be used to measure the beam size of a CW DC gun built as an electron source of FEL-THz facility in China Academmy of Engineering Physics (CAEP). The rms beam size is less than 1 mm and the average current of the electron beam is more than 1 mA. This new-type LW system ultilizes the excess power other the photocathode drive laser and becomes much cheaper and simpler. Plus, it can distinguish beams with different energies which are very close in ERLs. The system layout and the simulation results are also presented.

MOPME038	A New Theoretical Design of BLM System for HLS II	vacuum, scattering, monitoring, emittance	553
	Y.K. Chen, L.J. He, J. Li, W. Li, Y. Li USTC/NSRL, Hefei, Anhui, People's Republic of China
	Beam loss monitoring (BLM) system has been commonly used to detect the vacuum leakage. The existing BLM system for Hefei Light Source (HLS) was built in 2000. It played an important role in analyzing beam loss distribution and regulating the machine operation parameters. Recently, HLS is being upgraded to HLS II. The emittance will be decreased to increase the brilliance of synchrotron radiation. The Touschek lifetime will be much shorter than before, and dominate the total beam lifetime. It is necessary to redesign the BLM system for HLS II. The most important part of this work is to find a better method of monitoring Touschek lifetime by BLM system while keeping its general functions. According to the results of our research, a preliminary theoretical design for the new BLM system is proposed in this paper. This new system will play an important role in the storage ring commissioning, troubleshooting, and beam lifetime studying.

MOPME039	A New Method of Acquiring Fast Beam Transversal Profile in the Storage Ring	synchrotron, factory, synchrotron-radiation, simulation	556
	C. Cheng, P. Lu, B.G. Sun, K. Tang, F.F. Wu, Y.Y. Xiao, Y.L. Yang, Z.R. Zhou, J.Y. Zou USTC/NSRL, Hefei, Anhui, People's Republic of China
	A new method of acquiring fast beam transverse profile has been developed and will be used in HLS II. This method is based on four signals from MAPMT (multi-anode photo-multiplier tube) and logarithm processing technique. First, the calculation formula of beam transversal size and position are deduced using above method. Then, the main performances (e.g. sensitivity and linearity range) are analyzed. According to stimulation result, regardless of cross-talk and inconsistency between channels, the size signal has a linear relation with size s when s=0.8-2mm and position d=±2mm, the position signal has a linear relation with position d and the linear range exceeds ±2mm when s=0.8-2mm. With channel cross-talk and channel inconsistency being considered, the stimulation results also are given. Finally, a fast beam transverse profile monitor is designed and provides turn-by-turn measurement of the beam transverse profile.

MOPME049	Status of Non-destructive Bunch Length Measurement based on Coherent Cherenkov Radiation	radiation, target, diagnostics, vacuum	583
	H.X. Deng, S.L. Lu, T. Yu, J.B. Zhang SINAP, Shanghai, People's Republic of China G.A. Naumenko, A. Potylitsyn, M.V. Shevelev, D.A. Shkitov TPU, Tomsk, Russia
	Funding: This work was supported by the joint Russian-Chinese grant (RFBR 110291177 and NSFC 11111120065) and partially by the Program of Russian MES “Nauka” and the Chinese NSFC 11175240. As a novel non-destructive bunch length diagnostic of the electron beam, an experimental observation of the coherent Cherenkov radiation generated from a dielectric caesium iodide crystal with large spectral dispersion was proposed for the 30MeV femtosecond linear accelerator at Shanghai Institute of Applied Physics (SINAP). In this paper, the theoretical design, the experimental setup, the terahertz optics, the first angular distribution observations of the coherent Cherenkov radiation, and the future plans are presented. * Shevelev M. et al., Journal of Physics: Conf. Ser. 357 (2012) 012023.

MOPME051	Development of Cavity Beam Position Monitor System	cavity, FEL, simulation, coupling	586
	B.P. Wang, Y.B. Leng, Y.B. Yan, L.Y. Yu, R.X. Yuan, W.M. Zhou SINAP, Shanghai, People's Republic of China
	Shanghai soft X-ray free electron laser (SXFEL) facility requires beam position resolution better than 1 μm in the undulator sections. Cavity BPM system, feasible in obtaining sub micron position resolution, has been developed to achieve the goal. Two cavity prototypes with high Q and low Q were designed and fabricated. The relevant dedicated electronic, which could cover the two types of cavity BPMs, also have been developed. Fast fourier transform (FFT) and digital down converted based algorithms were implemented. The beam test of the whole system has been scheduled on the Shanghai deep ultraviolet (SDUV) FEL facility. The cavity design, electronic architecture, achieved performance during beam test will be presented.

MOPME058	DEVELOPMENT OF A CAVITY-TYPE BEAM POSITION MONITORS WITH HIGH RESOLUTION FOR ATF2	cavity, dipole, simulation, extraction	604
	S.W. Jang, E.-S. Kim KNU, Deagu, Republic of Korea Y. Honda, T. Tauchi, N. Terunuma KEK, Ibaraki, Japan
	We have developed a high resolution beam position monitors for ATF2 at KEK, which is an accelerator test facility for International Linear Collider(ILC). The main goals of ATF2 are achievement of 37nm beam size and 2nm beam position resolution for beam stabilization. For these goals, low-Q IP-BPM(Interaction Point Beam Position Monitor) with latency of 20 ns are being developed. In this paper, we will describe about design of Low-Q IP-BPM, the basics test results as RF test and BPM sensitivity test. Electronics for Low-Q IP-BPM will be also described.

MOPME060	Introduction to Beam Diagnostics Components for PAL-ITF	diagnostics, laser, gun, radiation	610
	H. J. Choi, M.S. Chae, J.H. Hong, C. Kim, D.T. Kim, S.J. Park PAL, Pohang, Kyungbuk, Republic of Korea
	Pohang Accelerator Laboratory (PAL) is building the 4th generation X-ray free electron laser (XFEL). The Injection Test Facility (ITF) is a test facility established to improve the functions of the laser gun and pre-injector to be installed in XFEL. To improve the effects of ITF, two factors are required. The first is to be able to generate low-emittance electron beams stably at the laser gun, and the second is to control increasing emittance by space charge effect by accelerating electron beams with high energy at the pre-injector. In this way, high-quality electron beams can be materialized. Various beam diagnostics are installed in the accelerator system for beam diagnostics and measurements. Five kinds of beam diagnostics were installed in the PAL-ITF. These are (1) ICT and (2) Faraday Cup to measure current and electrons charge, (3) Stripline BPM to measure the location of beams, (4) a YAG/OTR Screen Monitor to measure beam energy and transverse profile motion and (5) a Wire Scanner to measure beam size. In this paper, the purposes and properties of each diagnostic unit and measurement results are introduced.

MOPME061	Femtosecond e-bunch Length Measurement at fs-THz Accelerator at PAL	radiation, linac, laser, gun	613
	J.H. Ko, I.S. Ko POSTECH, Pohang, Kyungbuk, Republic of Korea H.-S. Kang PAL, Pohang, Kyungbuk, Republic of Korea
	Longitudinal distribution of femto-second electron beam has been evaluated by the coherent transition radiation Michelson interferometer with the reconstruction procedure from interferograms. We measure the bunch length of the Thz Accelerator using interferogram method in Pohang Accelerator Lab and compare with the energy of transition radiation and bunch length.

MOPME062	UV and X-ray Diffraction Radiation for Submicron Noninvasive Diagnostics	radiation, diagnostics, target, polarization	616
	D.Yu. Sergeeva, M.N. Strikhanov, A.A. Tishchenko MEPhI, Moscow, Russia
	Funding: This work was partially supported by Russian Ministry of Education and Science (State contract 12.527.12.5002). Diffraction radiation (DR) arises when a charged particle moves near a target. The theory of X-ray DR from single particles was created in [, ], and recently the theory has been developed for bunches [*]. DR from relativistic particles is used for noninvasive bunch diagnostics and also for creating new and effective sources of radiation, including Free-electron laser based on the Smith-Purcell effect. In the present work we explore theoretically DR from the bunch of ultrarelativistic charged particles at X-ray and UV frequencies domains. It is shown that incoherent part of form-factor, describing the effect of N electrons in bunch, exists and differs from the unity. The coherent part of radiation depends on transversal size of the bunch as ratio of the Bessel function to its argument. The coherence effects are proved to be important up to the wavelengths much less than transversal size of the bunch. The results obtained open the possibility to diagnose bunches of the submicron size with very high accuracy. A.A. Tishchenko et al, PLA. 359 (2006) 509. A.P. Potylitsyn et al, Diffraction radiation from relativistic particles, Springer, 2010 * D.Yu. Sergeeva et al, Proc. Channeling-2012, p.52, 2012

MOPME063	Backward X-ray Transition Radiation from Multilayered Target for Submicron Beam Diagnostics	radiation, target, diagnostics, polarization	619
	A.A. Tishchenko, D.Yu. Sergeeva, M.N. Strikhanov MEPhI, Moscow, Russia K.O. Kruchinin Royal Holloway, University of London, Surrey, United Kingdom
	Funding: This work was partially supported by Russian Ministry of Education and Science (State contract 12.527.12.5002). Backward transition radiation (TR) is a TR arising in the direction of mirror reflection relative to the charged particles trajectory. Therefore for oblique incidence it can be emitted under big angles which is useful from point of view of measuring of the radiation. In spite of the fact that backward TR in X-ray frequency domain is much weaker than forward TR [], it has recently been proposed by A.P. Potylitsyn and others [] as an instrument for submicron electron beam diagnostics. In this work we propose to use the multilayered target in order to enhance the resulting radiation, i.e. to use resonant backward X-ray TR. So far X-ray TR has not been explored theoretically for backward geometry. It is shown that the expressions obtained coincide in special case of forward resonant X-ray TR with the results by L. Durand () and X. Artru (*). We explore the spectral and angular characteristics of resonant backward X-ray TR form point of view of submicron beam diagnostics for the ultrarelativistic charged particles bunches. The role of absorption in the target material and also the coherent and incoherent parts of the radiation is analyzed A.A. Tishchenko et al, NIMB 227 (2005) 63. L.G. Sukhikh et al, J of Phys: Conf. Ser. 236 (2010) 012011. * L. Durand, Phys Rev D11 (1975) 89. **** X. Artru et al, Phys Rev D12 (1975) 1289.

MOPME067	Non-Invasive Bunch Length Diagnostics Based on Interferometry From Double Diffraction Radiation Target	target, radiation, diagnostics, FEL	631
	D.A. Shkitov, G.A. Naumenko, A. Potylitsyn, M.V. Shevelev TPU, Tomsk, Russia H.X. Deng, S.L. Lu, T. Yu, J.B. Zhang SINAP, Shanghai, People's Republic of China
	Funding: This work was supported by the joint Russian-Chinese grant (RFBR 110291177 and NSFC 11111120065) and partially by the Program of Russian MES “Nauka” and the SINAP Xinrui Program Y15501A061. Reliable and precise non-invasive beam diagnostics technique to measure length of sub-picosecond electron bunches are required for new accelerator facilities (FEL, et al.). Investigations of coherent radiation generated by such bunches using different interferometers allow to determine a bunch length. Measuring a dependence of radiation yield intensity from two DR targets on a distance between them (the intrinsic DR interferogram), it is possible to obtain the same information. Such a non-invasive technique can be directly used for ultra-short bunch length measurements. Recently the first experiment with a double DR target was carried out at the SINAP fs linac facility* with parameters described in**. The double DR target was consisted of two plates made from Al foil. The pyro-electric detector SPI-D-62 was used. Here we report the results of the second stage of our investigations. The DR interferograms of different electron bunch length were measured. The bunch length was reconstructed using the heuristic model based on the dimension theory and simulation data. We compare the results from DR interferograms and Michelson interferometer measurements and show their similarity. Murokh A. et al., NIMA 410 (1998) 452. Zhang J.B., Shkitov D.A. et al., IBIC’12 MOPB65 (2012). *Lin X., Zhang J. et al., Chin. Phys. Let. V. 27 N. 4 (2010) 044101.

MOPME068	Feasibility Study of a 2nd Generation Smith-Purcell Radiation Monitor for the ESTB at SLAC	radiation, simulation, background, vacuum	634
	N. Fuster Martinez, A. Faus-Golfe, J. Resta-López IFIC, Valencia, Spain H.L. Andrews LANL, Los Alamos, New Mexico, USA F. Bakkali Taheri, R. Bartolini, G. Doucas, I.V. Konoplev, C. Perry, A. Reichold, S.R. Stevenson JAI, Oxford, United Kingdom J. Barros, N. Delerue, M. Grosjean LAL, Orsay, France V. Bharadwaj, C.I. Clarke SLAC, Menlo Park, California, USA
	The use of a radiative process such as the Coherent Smith-Purcell Radiation (CSPR) is a very promising non-invasive technique for the reconstruction of the time profile of relativistic electron bunches. Currently existing CSPR monitors do not have yet single-shot capability. Here we study the feasibility of using a CSPR based monitor for bunch length measurement at the End Station Test Beam (ESTB) at SLAC. The aim is to design a second-generation device with single-shot capability, and use it as a diagnostic tool at ESTB. Simulations of the spectral CSPR energy distribution and feasibility study have been performed for the optimization of the parameters and design of such a device.

MOPME072	Performance Tests of a Short Faraday Cup Designed for HIE-ISOLDE	ion, diagnostics, cryomodule, cryogenics	646
	E.D. Cantero, W. Andreazza, E. Bravin, M.A. Fraser, D. Lanaia, A.G. Sosa, D. Voulot CERN, Geneva, Switzerland
	Funding: E.D.C, D.L. and A.S. acknowledge CATHI Marie Curie ITN: EU-FP7-PEOPLE-2010-ITN Project number 264330. M.A.F acknowledges co-funding by the European Commission (Grant agreement PCOFUND-GA-2010-267194) The On-Line Isotope Mass Separator (ISOLDE) facility at CERN is being upgraded in order to deliver higher energy and intensity radioactive beams. The final setup will consist in replacing the energy variable part of the normal conducting REX post-accelerator with superconducting cavities. In order to preserve the beam emittance, the drift space between the cryomodules housing these cavities has been kept to a minimum. As a consequence, the longitudinal space available for beam diagnostics is severely limited in the inter-cryomodule regions. A Faraday cup (FC) will be installed to measure beam currents, and due to the tight spatial constraints, its length is much smaller than usual. This poses a great challenge when trying to avoid the escape of ion-induced secondary electrons, which would falsify the current measurement. Two prototypes of such a short FC have therefore been tested at REX-ISOLDE using several beam intensities and energies, with the aim of determining its accuracy. In this paper the experimental results obtained for the two prototype cups are presented together with numerical calculations of the electrostatic fields that are produced inside the cup.

MOPME075	Laser Based Stripping System for Measurement of the Transverse Emittance of H⁻ Beams at the CERN LINAC4	laser, linac, background, emittance	652
	T. Hofmann, E. Bravin, U. Raich, F. Roncarolo CERN, Geneva, Switzerland B. Cheymol ESS, Lund, Sweden
	Funding: LA3NET is funded by the European Commission under Grant Agreement Number GA-ITN-2011-289191 The new LINAC4 at CERN will accelerate H⁻ particles to 160 MeV and allow high brightness proton beam transfers to the Proton Synchrotron Booster, via a charge-exchange injection scheme. This paper describes the conceptual design of a laser system proposed for transverse profile and emittance measurements based on photon detachment of electrons from the H⁻ ions. The binding energy of the outer electron is only 0.75 eV and can easily be stripped with a laser beam. Measuring the electron signal as function of the laser position allows the transverse beam profile to be reconstructed. A downstream dipole can also be used to separate the laser neutralized H⁰ atoms from the main H⁻ beam. By imaging these H⁰ atoms as a function of laser position the transverse emittance can be reconstructed in the same way as in traditional slit-and-grid systems. By properly dimensioning the laser power and spot size, this method results in negligible beam losses and is therefore non-destructive. In addition, the absence of material intercepting the H⁻ beam allows the measurement of a full power H⁻ beam. This paper will focus on the general design and integration of both the laser and H⁰ detector systems.

MOPME077	Electro-0ptical Bunch Profile Measurement at CTF3	laser, photon, vacuum, polarization	658
	R. Pan, A. Andersson, W. Farabolini, A. Goldblatt, T. Lefèvre, M. Martyanov, S. Mazzoni, S.F. Rey, L. Timeo CERN, Geneva, Switzerland W.A. Gillespie, R. Pan, D.A. Walsh University of Dundee, Nethergate, Dundee, Scotland, United Kingdom S.P. Jamison STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	A new electro-optic bunch profile monitor has recently been installed in CLIC Test Facility 3 at CERN. The monitor is based on an electro-optic spectral decoding scheme which reconstructs the longitudinal profile of the electron bunch by measuring its Coulomb field. The system uses a 780 nm fibre laser system, transported over a 20m long distance to the interaction chamber, where a ZnTe crystal is positioned close to the beam. The assembly also contains a traditional OTR screen, which is coupled to a second optical line and used to adjust the temporal overlap between the laser and the electron pulse. This paper presents the detection system in detail, as well as reporting on the first measurements performed with beam.

MOPWA018	CW-type HV Power Supply of 50 Hz and its Application in Accelerator Power Supply	high-voltage, power-supply, impedance, damping	699
	Z.-F. He, D.M. Li, Y.H. Liu, S.L. Wang, J.-L. Zhang, Y.-T. Zhang SINAP, Shanghai, People's Republic of China
	Funding: The Knowledge Innovation Program of Chinese Academy of Sciences 　　The high-voltage power supply is an integral part of accelerator technology, as its stable and reliable output is an important guarantee for accelerator properly working. In a number of engineering practice of accelerator design and construction, we tried to use the Cockcroft-Walton (CW) type of power supply driven by 50 Hz and got success. It is of simple structure, low cost, easy maintenance, and high efficiency. This report describes the technical difficulties and the solutions in the CW-type power supply driven by 50 Hz. It also gives an introduction of the latest design of 800 kV/30 mA electron accelerator, which is being assembled at SINAP. Recent work has shown that it is an option to choose 50 Hz driven power system when it is more lenient on the voltage ripple but needed to be as high as possible on the energy conversion efficiency.

MOPWA021	Design of the Air Cooling System for the High Voltage Power Supply of a Electron Accelerator	power-supply, high-voltage, simulation, radiation	705
	F. Zhong, X. Lei, J. Yang, L. Yang HUST, Wuhan, People's Republic of China
	High voltage electron accelerators are widely applied in many fields of radiation pro-cessing,and the high voltage power supply is the critical equipment for the accelerator. for the requirement of high voltage, the design of locate the power supply in a steel barrel filled with SF6 is commonly used. Considering the various losses of the power supply, an air-cooling system is needed. This paper presents the design of the air-cooling system for the high voltage power supply. The fluid simulation of SF6 based on Fluent and the optimal design of the air duct's structure and the thermal efficiency have been done. The comparison and analysis of the simulation and the empirical formula result is also carried out. It illustrates the design of the air-cooling system can satisfy the demand of the heat radiation This paper also provides an effective method for the optimal design of the air duct's structure and the maximize efficiency of heat exchange.

MOPWA030	Upgrade of the LHC Injection Kicker Magnets	vacuum, kicker, injection, impedance	729
	M.J. Barnes, P. Adraktas, V. Baglin, G. Bregliozzi, S. Calatroni, F. Caspers, H.A. Day, L. Ducimetière, M. Garlaschè, V. Gomes Namora, J.M. Jimenez, N. Magnin, V. Mertens, E. Métral, B. Salvant, M. Taborelli, J.A. Uythoven, W.J.M. Weterings CERN, Geneva, Switzerland
	The two LHC injection kicker systems, comprising 4 magnets per ring, produce a kick of 1.3 T.m with a rise-time of less than 900 ns and a flattop ripple of less than ±0.5%. A beam screen is placed in the aperture of each magnet, to provide a path for the image current of the high intensity LHC beam and screen the ferrite yoke against wake fields. The screen consists of a ceramic tube with conductors in the inner wall. The initially implemented beam screen ensured a low rate of electrical breakdowns while providing an adequate beam coupling impedance. Operation with increasingly higher intensity beams, stable for many hours at a time, now results in substantial heating of the ferrite yoke, sometimes requiring cool down over several hours before the LHC can be refilled. During the long shutdown in 2013/2014 all 8 kicker magnets will be upgraded with an improved beam screen and an increased emissivity of the vacuum tank. In addition equipment adjacent to the injection kickers and various vacuum components will also be modified to help reduce the vacuum pressure in the kickers during high-intensity operation. This paper discusses the upgrades as well as their preparation and planning.

MOPWA034	Electron Tracking Simulations in the Presence of the Beam and External Fields	emittance, simulation, proton, space-charge	741
	M. Patecki, B. Dehning, G. Iadarola, M. Sapinski CERN, Geneva, Switzerland
	The ionisation profile monitors installed in the CERN LHC and SPS, makes use of the ionisation of small quantities of injected neon gas by the circulating beam. The electrons produced are guided towards the readout system using a combination of electric and magnetic fields. However, in the presence of the beam field their tracks are modified and the resulting profile is distorted. The Geant4 physics simulation package has been used to simulate the ionisation process, while the CERN-developed PyECLOUD code has been used for tracking the resulting ionised particles. In this paper the results of simulations are compared with observations, with conclusions presented on the accuracy of the reconstruction of high-intensity beam profiles.

MOPWA036	GEM Detectors for the Transverse Profile Measurement of Low Energy Antiprotons and High Energy Hadrons	antiproton, hadron, cathode, scattering	747
	J. Spanggaard, P. Carriere, S.C. Duarte Pinto, G. Tranquille CERN, Geneva, Switzerland
	Gas Electron Multipliers (GEM) are finding more and more applications in beam instrumentation. Gas Electron Multiplication is a very similar physical phenomenon to that which occurs in Multi Wire Proportional Chambers (MWPC), but for small profile monitors GEMs are much more cost effective to produce and maintain. In 2012, all Multi-Wire Proportional Chambers in the experimental areas of the Antiproton Decelerator at CERN were successfully replaced by Gas Electron Multipliers. This paper describes the choice of detector and reports on the commissioning of 20 GEM detectors for transverse profile measurement on low energy antiproton beams (5.3 MeV, equal to 100 MeV/c). It will also cover the development of, and first results from, a new 200x200 mm GEM detector for profiling the high energy muon beam (172 GeV/c) delivered to the COMPASS experiment and discuss the outlook for replacing all Multi-Wire Proportional Chambers in the CERN experimental areas by GEM based monitors.

MOPWA038	Flashbox Compact Beam Spectrometer and its Application to the High-gradient Acceleration Study	ion, dipole, acceleration, accelerating-gradient	753
	A. Dubrovskiy, F. Tecker CERN, Geneva, Switzerland M. Jacewicz, R.J.M.Y. Ruber, V.G. Ziemann Uppsala University, Uppsala, Sweden
	A Flashbox compact spectrometer has been developed for the Two-beam Test Stand (TBTS), which is a part of the CLIC test facility CTF3 at CERN. It is used to study limitations of high-gradient acceleration in X-band structures being prototyped in the TBTS. The Flashbox is built around the beam tube such that an electron beam can pass to be accelerated in the X-band structure while charged particles emitted from the accelerating structure can be intercepted on the spectrometer consisting of detector plates aligned along the beam axis in combination with magnetic and electric fields. The Flashbox has made it possible to identify electrons and ions emitted by the accelerating structure during RF breakdown. We describe the Flashbox and first results.

MOPWA050	Bunch Train Characterisation for an Infra-red FEL Driven by an Energy Recovery Linac	FEL, pick-up, EPICS, diagnostics	786
	T.T. Thakker, D. Angal-Kalinin, D.J. Dunning, F. Jackson, S.P. Jamison, J.K. Jones, N. Thompson STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	The IR-FEL on the ALICE test facility in the UK first achieved lasing in October 2010 and has since been characterised in terms of its output . In this work we make a characterisation of electron bunch properties along a complete 100us macropulse to characterise the lasing-induced energy change and its effect on energy recovery. Measurements of bunch energy and timing are correlated with the FEL radiation output and discussed. N. R. Thompson et al, ‘First lasing of the ALICE infra-red Free-Electron Laser’, Nuclear Instruments and Methods A, 680 (2012) 117–123

MOPWA051	ZEMAX Simulations for an Optical System for a Diffraction Radiation Monitor at CesrTA	target, radiation, simulation, damping	789
	T. Aumeyr, V. Karataev JAI, Egham, Surrey, United Kingdom M.G. Billing CLASSE, Ithaca, New York, USA L.M. Bobb, B. Bolzon, T. Lefèvre, S. Mazzoni CERN, Geneva, Switzerland
	Diffraction Radiation (DR) is produced when a relativistic charged particle moves in the vicinity of a medium. The target atoms are polarized by the electric field of the charged particle, which then oscillate thus emitting radiation with a very broad spectrum. The spatial-spectral properties of DR are sensitive to various electron beam parameters. Since the energy loss due to DR is so small that the electron beam parameters are unchanged, DR can be used to develop non-invasive diagnostic tools. The aim of this project is to measure the transverse (vertical) beam size using incoherent DR. To achieve the micron-scale resolution required by CLIC, DR in the UV and X-ray spectral-range must be studied. During the next few years, experimental validation of such a scheme will be conducted on the CesrTA at Cornell University, USA. This paper reports on simulations carried out with ZEMAX, studying the optical system used to image the emitted radiation.

MOPWA053	Sub-Micrometre Resolution Laserwire Transverse Beam Size Measurement System	laser, alignment, photon, background	795
	L.J. Nevay, G.A. Blair, S.T. Boogert, V. Karataev, K.O. Kruchinin Royal Holloway, University of London, Surrey, United Kingdom A.S. Aryshev, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan L. Corner, R. Walczak Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	Funding: The research leading to these results has received funding from the European Commission under the FP7 Research Infrastructures project Eu-CARD, grant agreement no. 227579 We present the results from the laserwire system at the Accelerator Test Facility 2 (ATF2) during recent operation after relocation to the virtual image point of the ATF2 final focus. The characterisation of the 150 mJ, 77 ps long laser pulses at a scaled virtual interaction point is used to deconvolve the transverse laserwire profile demonstrating a 1.16 ± 0.06 um vertical electron beam profile. Horizontal laserwire scans were used in combination with the vertical scans to measure the electron beam size using a full overlap integral model due to the problems presented by a large aspect ratio electron beam.

MOPWA056	Spectra of Coherent Smith-Purcell Radiation Observed from Short Electron Bunches: Numerical and Experimental Studies	radiation, diagnostics, simulation, target	801
	F. Bakkali Taheri, G. Doucas, I.V. Konoplev, A. Reichold JAI, Oxford, United Kingdom H.L. Andrews LANL, Los Alamos, New Mexico, USA R. Bartolini Diamond, Oxfordshire, United Kingdom V. Bharadwaj, C.I. Clarke SLAC, Menlo Park, California, USA N. Delerue LAL, Orsay, France N. Fuster Martinez IFIC, Valencia, Spain J.D.A. Smith TXUK, Warrington, United Kingdom P. Stoltz Tech-X, Boulder, Colorado, USA
	Funding: This work performed [in part] under DOE Contract DE-AC02-7600515 There is a significant interest in the development of compact particle accelerators within research areas including X-ray and THz (T-ray) sources of radiation, particle physics and medical sciences. To support the progress in these areas, non-invasive, electron beam diagnostics that are capable of measuring a single femtosecond electron bunch are required. At the current stage such beam diagnostics for femtosecond-long electron bunches are still not available. The goal of the work presented is to understand the spectral characteristics of coherent Smith-Purcell radiation to enable its quick and reliable interpretation including the longitudinal profile reconstruction of electron bunches. The research presented comprises results from numerical modelling and experimental studies. Using the numerical data, we discuss the radiated spectra dependence on the electron bunch profile and analyse the results. We also discuss the experimental data and compare it with theoretical predictions.

MOPWA060	DITANET - An International Network in Beam Diagnostics	diagnostics, photon, instrumentation, synchrotron	813
	C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom C.P. Welsch The University of Liverpool, Liverpool, United Kingdom
	Funding: Work supported by the EU under contract 215080. Beam diagnostics systems are essential constituents of any particle accelerator; they reveal the properties of a beam and how it behaves in a machine. Without an appropriate set of diagnostic elements, it would simply be impossible to operate any accelerator complex, let alone optimize its performance. Beam diagnostics is also a rich field in which a great variety of physical effects are made use of and consequently provides a wide interdisciplinary base for the training of researchers. The DITANET Consortium develops beyond state-of-the-art beam diagnostic techniques for hadron and electron accelerators and trained more than 20 researchers between 2008 and 2012. This contribution summarizes the network's research outcomes in beam instrumentation and diagnostics.

MOPWA063	Proposed Coherent Diffraction Radiation Measurements of Bunch Length at ASTA	radiation, cryomodule, gun, laser	822
	A.H. Lumpkin, J. Ruan, R.M. Thurman-Keup Fermilab, Batavia, USA
	Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy. The feasibility of using the autocorrelation of coherent diffraction radiation (CDR) as a non-intercepting diagnostics technique for bunch length and indirectly rf phase measurements is evaluated and proposed for the Advanced Superconducting Test Accelerator (ASTA) facility under construction at Fermilab. Previous experiments on an rf thermionic cathode gun beam at 50 MeV provide a proof-of-principle reference for the ASTA injector. The ASTA injector is based on an L-band rf photocathode (PC) gun with UV pulse drive laser, two L-band superconducting accelerator structures, a chicane bunch compressor, and an electron spectrometer. The injector energy of 40-50 MeV is expected. The 3-MHz micropulse repetition rate with micropulse charges up to to 3.2 nC and 1-ps bunch lengths should generate sufficient CDR signal for standard pyroelectric detectors to be used. The CDR signals will also be evaluated as a bunch compression signal for beam-based feedback for rf phase. The technique would also be applicable at high energy in straight transport lines after the cryomodules.

MOPWA064	Microwave Resonator Diagnostics of Electron Cloud Density Profile in High Intensity Proton Beam	cavity, proton, vacuum, simulation	825
	Y.-M. Shin, J. Ruan, C.-Y. Tan, J.C.T. Thangaraj, R.M. Zwaska Fermilab, Batavia, USA
	We have developed an novel technique to accurately estimate the density of dilute electron clouds emitted from high intensity proton beams. The strong phase shift enhancement from multiple reflections of standing microwaves in a resonating beam pipe cavity has been demonstrated with numerical modeling using dielectric approximation and e S-parameter measurements. The equivalent dielectric simulation showed a ~ 10 times phase shift enhancement (Pi-mode, 1.516 GHz) with the cavity beam pipe compared to the waveguide model. The position-dependence of the technique is investigated by overlapping the field distributions of harmonic resonances. The simulation with various positions of dielectric insertions confirmed that resonance peaks in phase-shift spectra corresponding to the relative distance between field-nodes and electron cloud position, which allows for one-dimensional mapping. Preliminary experimental studies based on a bench-top setup confirm the results of the simulation showing that thicker reflectors enhance the phase-shift measurement of the electron cloud density.

MOPWA069	Time-resolved Electron Beam Position Monitor Macropulse Waveform Measurement in MkV Linear Accelerator at University of Hawaii Free Electron Laser Laboratory	FEL, controls, free-electron-laser, laser	837
	P. Niknejadi, M.R. Hadmack, B.T. Jacobson, J. Madey, G.S. Varner University of Hawaii, Honolulu, HI, USA
	Real time waveform measurements of electron beams will provide valuable data and possibility of online bunch diagnostics in linear accelerators. The University of Hawaii Linear Accelerator utilizes a thermionic LaB6 cathode microwave gun injector and a single section of S-band linear accelerator capable of producing a 40MeV, 1-2 ps bunched electron beam with average current of 200mA over the duration of a 4.5 us macropulse. This beam, pulsed at 4 Hz, produces strong RF signal at 2.856 GHz which is coupled out of the beam-pipe by a family of stripline beam position monitors (BPM's) and read out using custom built logarithmic-difference based electronics installed in 2012.* A high speed Analog to Digital Convertor and Field-Programmable Gate Array will be used to digitize the signal and record the waveform. The goal is to make a cost effective oscilloscope on a chip/board with feasible and functional operation to achieve optimal beam configuration. The circuit board design, in-circuit programming, waveform digitization challenges, and preliminary results from the prototype will be presented at the conference. * B. T. Jacobson, M. R. Hadmack, J. M. J. Madey, P. Niknejadi "Modular Logarithmic Amplifier Beam Position Monitor Readout System at University of Hawai’i," IBIC Conf. Proc. (2012)

MOPWA071	A Comparison of Electron Cloud Density Measurements at CesrTA	simulation, positron, resonance, pick-up	843
	J.P. Sikora, J.A. Crittenden, D.O. Duggins, Y. Li, X. Liu CLASSE, Ithaca, New York, USA S. De Santis LBNL, Berkeley, California, USA
	Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505. Several techniques have been employed to measure the electron cloud (EC) density in accelerators. These include Time Resolved Retarding Field Analyzers (TR-RFA) and Shielded Pickups (SPU) that measure the flux of cloud electrons onto the beam-pipe wall, as well as TE wave resonance techniques that measure the EC density in a region within the volume of the beam-pipe. We have made measurements to test the EC mitigation properties of different surface coatings and geometries, often with more than one technique used in the same test chamber. We present a comparison of bare aluminum chambers with those having a TiN coating, as well as the effect of beam conditioning. In addition, we will compare the results of the different measurement techniques used in the same chamber. These measurements were made at the Cornell Electron Storage Ring (CESR) which has been reconfigured as a test accelerator (CesrTA) having positron or electron beam energies ranging from 2 GeV to 5 GeV.

MOPWA072	MODELING FOR TIME-RESOLVED RETARDING FIELD ANALYZER MEASUREMENTS OF ELECTRON CLOUD BUILDUP AT CesrTA	vacuum, positron, dipole, pick-up	846
	J.A. Crittenden, Y. Li, X. Liu, M.A. Palmer, J.P. Sikora CLASSE, Ithaca, New York, USA
	Funding: 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 mitigation techniques using custom vacuum chambers. Multibunch electron and positron beams of energies between 2.1 and 5.3 GeV with bunch spacings from 4 to 98 ns and bunch populations ranging from 10¹⁰ to 16·10¹⁰ provide highly differentiated sensitivity to the processes contributing to cloud buildup such as photoelectron production, cloud space-charge dynamics, and secondary electron emission. Measurements of the time dependence of cloud buildup using BPM-style shielded pickups have been shown to provide tight constraints on cloud buildup models. Recently, time-resolving retarding-field analyzers have been designed, installed and commissioned. These novel detectors combine the time-resolving feature of the shielded pickups with the fine transverse segmentation and cloud electron energy sensitivity of the time-integrating retarding-field analyzers used previously. We report on progress in modeling these measurements and quantify their sensitivity to various parameters describing the underlying physical processes contributing to cloud buildup.

MOPWA073	A Turn-by-turn Beam Profile Monitor using Visible Synchrotron Radiation at CESR-TA	synchrotron, synchrotron-radiation, radiation, emittance	849
	S. Wang, D. L. Rubin, C.R. Strohman CLASSE, Ithaca, New York, USA R.F. Campbell, R. Holtzapple CalPoly, San Luis Obispo, California, USA
	Funding: Work supported by the National Science Foundation and Department of Energy under contract numbers PHY-0734867, PHY-1002467, DMR-0936384, and DE-FC02-08ER41538, DE-SC0006505 A fast beam profile monitor using visible synchrotron radiation (SR) has been constructed and installed in Cornell Electron Storage Ring. This monitor utilizes fast readout electronics based on the Hamamatsu H7260K multi-anode photomultiplier, which has a 32-channel linear array with 1mm channel pitch and sub-nanosecond rise time. In a low emittance lattice at 2 GeV, a double-slit interferometer is employed to measure the horizontal beam size. After careful calibration of the interference pattern, the horizontal beam size within a range of 100 to 500 microns can be measured with a precision of ±5 microns. Due to finite array size, the small vertical beam size is measured by imaging the pi-polarized component of the SR. The fast beam profile monitor is capable of measuring bunch-by-bunch turn-by-turn transverse beam sizes, which eliminates beam jitter inherent when imaging the average beam size with a CCD camera. Details of hardware and software controls are also discussed.

MOPWA078	The Calibration of the PEPPo Polarimeter for Electrons and Positrons	positron, photon, target, polarization	861
	A.H. Adeyemi JLAB, Newport News, Virginia, USA E. J-M. Voutier LPSC, Grenoble, France
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 The PEPPo (Polarized Electrons for Polarized Positrons) experiment at Jefferson Laboratory investigated the polarization transfer from longitudinally polarized electrons to longitudinally polarized positrons, with the aim of developing this technology for a low energy (~MeV) polarized positron source. Polarization of the positrons was measured by means of a Compton transmission polarimeter where incoming positrons transfer their polarization into circularly polarized photons that were subsequently analyzed by a thick polarized iron target. The measurement of the transmitted photon flux with respect to the orientation of the target polarization (±) or the helicity (±) of the incoming leptons provided the measurement of their polarization. Similar measurements with a known electron beam were also performed for calibration purposes. This presentation will describe the apparatus and calibrations performed at the injector at the Jefferson Laboratory to measure positron polarization in the momentum range 3.2-6.2 MeV/c, specifically to quantify the positron analyzing power from electron experimental data measured over a comparable momentum range. 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

MOPWA079	Characterization of the Analyzing Target of the PEPPo Experiment	target, polarization, positron, photon	864
	O. Dadoun LAL, Orsay, France E. Froidefond, E. J-M. Voutier LPSC, Grenoble, France
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 Various methods have been investigated over the past decades for the production of polarized positrons. The purpose of the PEPPo (Polarized Electrons for Polarized Positrons) experiment is to demonstrate, for the first time, the production of polarized positrons from a polarized electron beam. This two-step process involves the production of circularly polarized photons in a high Z target via the bremsstrahlung process followed, within the same target, by the conversion of polarized photons into polarized e⁺e⁻ pairs through the pair creation process. The PEPPo experiment was performed in Spring 2012 at the injector of the Jefferson Laboratory using a highly spin-polarized (~85%) 8.3 MeV/c electron beam. The positron polarization was measured by means of a Compton transmission polarimeter over the momentum range from 3.2 MeV/c to 6.2 MeV/c. This presentation will discuss the experimental set-up with a special emphasis on the analyzing magnet constituting the polarization filter of the experiment. The knowledge of the analyzing target polarization will be discussed on the basis of simulations and calibrated to experimental data 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

MOPWA080	Design of a Fast, XFEL-quality Wire Scanner	photon, radiation, vacuum, instrumentation	867
	M.A. Harrison, R.B. Agustsson, P.S. Chang, T.J. Hodgetts, A.Y. Murokh, M. Ruelas RadiaBeam, Santa Monica, USA
	RadiaBeam Technologies, in collaboration with the Pohang Accelerator Laboratory, has designed and built a fast wire scanner for transverse beam size measurements in the XFEL Injector Test Facility. The wire scanner utilizes three 25-micron diameter tungsten wires mounted vertically, horizontally, and diagonally on a single alumina card to measure the transverse beam size down to 10 microns with sub-micron accuracy of a 139-MeV electron beam. A double-ended design using dual bellows for actuation is used to reduce the vibrations of the wire holder during motion and negate the effects of air pressure on positioning. The servomotor-driven system is capable of performing full horizontal, vertical, and 45-degree scans in under a minute. Algorithms are presented for removing the broadening effect of the wires' thickness from the scanning data to measure beams that are as small or smaller than the wires. Furthermore, we present formulas for determining the beam's transverse spatial sizes (horizontal and vertical spot size and correlation) from the scan data.

MOPWO003	Multibunch Tracking Code Development to Account for Passive Landau Cavities	cavity, damping, impedance, radiation	885
	M. Klein, R. Nagaoka SOLEIL, Gif-sur-Yvette, France
	The MAX IV 3 GeV storage ring will achieve an ultra-low horizontal emittance of 0.24 nm rad by using a multibend achromat lattice. Passive harmonic cavities are introduced to relax the Touschek-lifetime and intrabeam scattering issues as well as fight collective beam instabilities via Landau damping. Since instabilities occur during injection, when the passive harmonic cavity potential is also time varying, it became important to simulate this transient process. The most promising approach was considered to be multibunch tracking which also allows for an arbitrary filling pattern. Since every bunch is represented by numerous macroparticles, internal motions as well as microstructures in the charge distribution can be followed.

MOPWO004	Simulations and Studies of Electron Beam Dynamics under Compton Back-scattering for the Compact X-ray Source ThomX	simulation, wakefield, collective-effects, photon	888
	I.V. Drebot, C. Bruni, N. Delerue, T. Demma, A. Variola, Z.F. Zomer LAL, Orsay, France A. Loulergue SOLEIL, Gif-sur-Yvette, France
	Funding: This work is supported by the French "Agence Nationale de la Recherche" under reference ANR-10-EQPX-51, and also by grants from Région Ile-de-France, Université Paris-Sud and IN2P3/CNRS. In this article are presented beam dynamics investiga- tions of a relativistic electron bunch in the compact storage ring ThomX (50 MeV), which is under construction at LAL to produce hard X-ray using Compton Back-Scattering (CBS). The effect of CBS has been implemented in a 6D tracking code. In addition to CBS, the influence of lattice non linearities and various collective effects on the flux of scattered Compton photons is investigated.

MOPWO009	Numerical Studies on the Impact of Ionized Residual Gas on an Electron Beam in an ERL	ion, emittance, simulation, linac	903
	G. Pöplau, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany A. Meseck HZB, Berlin, Germany
	Funding: Supported by BMBF under contract number 05K10HRC Energy Recovery Linacs (ERLs) are the most promising candidates for next-generation light sources now under active development. An optimal performance of these machines requires the preservation of the high beam brightness generated in the injector. For this, the impact of the ionized residual gas on the beam has to be avoided as it causes instabilities and emittance growth. Typical measures to reduce the effect of ion clouds are clearing electrodes and clearing gaps in the bunch train. In this paper, we present numerical studies of the impact of ion clouds on the electron bunch train. The simulations are performed with the software package MOEVE PIC Tracking developed at Rostock University. ’The model for the bunch and the ion cloud takes into account a distribution of macro particles. The interaction of the bunch with the ion cloud is computed with a 3D space charge model. Hence, particle tracking allows for detailed studies of bunch characteristics such as the emittance. The presented numerical investigations take into account the parameters of the ERL BERLinPro with the objective to deduce appropriate measures for the design and operation of BERLinPro.

MOPWO014	Numerical Methods to the Space Charge Compensation (SCC) Effect of the LEBT Beam	ion, space-charge, simulation, ion-source	915
	S.X. Peng, J. Chen, J.E. Chen, Z.Y. Guo, P.N. Lu, Y.T. Luo, H.T. Ren, Z.H. Wang, Y. Xu, T. Zhang, J. Zhao PKU, Beijing, People's Republic of China A.L. Zhang Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China
	Numerical simulation as well as experimental researches on space charge compensation for high intensity, low energy ion beam has been done at Peking University (PKU). In this paper we will describe the simulation model proposed at PKU and use it on the PKU ECR single-charged ion source. It consists of a new concept of equivalent density and more consideration of physical process. A series of arithmetical equations is gained through theoretical derivation. Although no numerical solutions have been carried out from our computation, it is foreseeable that the final result will be achieved soon.

MOPWO036	Civil Engineering Feasibility Studies for Future Ring Colliders at CERN	linac, civil-engineering, collider, hadron	969
	J.A. Osborne, O.S. Brüning, M. Klein, S. Myers, S. Myers, L. Rossi, C.S. Waaijer, F. Zimmermann CERN, Geneva, Switzerland M. Klein DESY Zeuthen, Zeuthen, Germany
	CERN civil engineers are studying the feasibility of future ring colliders to complement the LHC. Infrastructure works typically represent one third of the cost of major physics projects, so it's critical that the construction costs are well understood from the conceptual stage. This poster presents the first results of the feasibility studies for two potential ring colliders at CERN: the racetrack shaped Linac-Ring LHeC and an 80km circular tunnel to house the High Energy LHC (SHE-LHC) and the TLEP. Some of the key civil engineering challenges faced in such large scale projects are presented with particular emphasis on geology, design and risk.

MOPWO043	Hollow Electron Lens Simulation for the SPS	simulation, collimation, optics, proton	990
	V. Previtali, G. Stancari, A. Valishev Fermilab, Batavia, USA S. Redaelli CERN, Geneva, Switzerland
	Funding: Fermilab is operated by Fermi Research Alliance, LLC, Contract No. DE-AC02-07CH11359 with the United States Dep. of Energy. This work was supported by the US LHC Accelerator Research Program (LARP). The hardware of the Tevatron hollow electron lens, which has been used in the past for collimation purposes, is presently available. Possible applications of similar devices in the LHC are under evaluation, but a realistic date for installation of electron lenses in the LHC would be not earlier than the machine shutdown scheduled for 2018. We investigated the possibility of beam tests with the available hardware in the meantime in the SPS. This article aims to answer this question by presenting the results of dedicated numerical simulations.

MOPWO044	Numerical Simulations of a Hollow Electron Lens as a Scraping Device for the LHC	simulation, collimation, resonance, proton	993
	V. Previtali, G. Stancari, A. Valishev Fermilab, Batavia, USA S. Redaelli CERN, Geneva, Switzerland
	Funding: Fermilab is operated by Fermi Research Alliance, LLC, Contract No.DE-AC02-07CH11359 with the United States Dep. of Energy. This work was partially supported by US LHC Accelerator Research Program(LARP) The use of hollow electron beam lens for scraping high energy proton beams has been extensively tested at Fermilab's Tevatron collider. In order to evaluate a possible application of a similar a device in the LHC, a dedicated new routine has been implemented in the standard 6D tracking code used at CERN for the design of the LHC collimation system. The effects of a finite length cylinder of electrons encompassing the main proton beam and traveling in the opposite direction is described in the routine. Realistic electron distributions, including measured radial imperfections, have been included in the model. Various operating modes have been simulated for the 7 TeV machine operation with sextupoles and octupoles included. The loss rate caused by the electron lens has been studied through an extended simulation campaign; the obtained halo removal rates for the different electron lens operating modes are presented.

MOPWO054	The LHeC as a Higgs Boson Factory	linac, luminosity, factory, lepton	1017
	F. Zimmermann, O.S. Brüning CERN, Geneva, Switzerland M. Klein The University of Liverpool, Liverpool, United Kingdom
	The LHeC is designed to collide a new 60 GeV energy electron beam, from a 3-pass ERL, with the 7 TeV energy LHC proton beam. At the present target ep luminosity of 10³³cm^-2s^-1, the LHeC would produce a few 1000 Higgs bosons per year, allowing for precision coupling measurements, especially of the H –> b bbar decay in charged current deep inelastic scattering (ep –> nu H X). With a significant increase of the luminosity, rarer channels become accessible, as the charm decay. Here such an increase, to the level of 10³⁴cm^-2s^-1 or even beyond, is considered from a combination of improvements, namely with a smaller proton beam emittance, with a further reduction of the proton IP beta function, an increase of the proton bunch intensity and with doubling the lepton beam current, compared to the canonical values assumed in the CDR.

MOPWO059	Development of MATLAB-based Application Programs for the Optics Matching, Beam Steering, and Injection Conditioning in TPS Commissioning	linac, optics, injection, lattice	1025
	M.-S. Chiu, H.-P. Chang, P.J. Chou, F.H. Tseng NSRRC, Hsinchu, Taiwan
	Taiwan Photon Source (TPS) is a third generation 3GeV synchrotron light source. Its first beam commissioning is scheduled in 2014. Intensive efforts are devoted to achieve efficient transportation of the first beam from the LINAC, passing through the LTB transfer line, and its injection into the booster ring. After the beam energy has been ramped up to 3GeV in booster, the beam is extracted to the BTS transfer line. At the end of BTS, the beam is injected into the storage ring and circulates around the storage ring. In order to achieve efficient beam transportation, we have developed various MATLAB-based commissioning tools for the optics matching of transfer lines, beam steering and injection conditioning of booster and storage ring.

MOPWO062	A Parallel Multi-objective Differential Evolution Algorithm for Photoinjector Beam Dynamics Optimization	controls, emittance, solenoid, gun	1031
	J. Qiang, C.E. Mitchell, S. Paret, R.D. Ryne LBNL, Berkeley, California, USA Y.X. Chao UCB, Berkeley, California, USA
	Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231 In photoinjector design, there is growing interest in using multi-objective beam dynamics optimization to minimize the final transverse emittances and to maximize the final peak current of the beam. Most previous studies in this area were based on genetic algorithms. Recent progress in optimization suggests that the differential evolution algorithm could perform better in comparison to the genetic algorithm. In this paper, we propose a new parallel multi-objective optimizer based on the differential evolution algorithm for photoinjector beam dynamics optimization. We will discuss the numerical algorithm and some benchmark examples. This algorithm has the potential to significantly reduce the computation time required to reach the optimal Pareto solution.

MOPWO068	Simulating Electron Cloud Evolution using Modulated Dielectric Models	simulation, plasma, diagnostics, proton	1043
	S.A. Veitzer, P. Stoltz Tech-X, Boulder, Colorado, 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 the SCiDAC-3 project (DE-SC0008920) Electron clouds can pose a serious threat to accelerator performance, and understanding cloud buildup and the effectiveness of different mitigation techniques can provide cost-saving improvements in accelerator design and fabrication. Microwave diagnostics of electron clouds are a non-destructive way to measure cloud buildup, but it is very difficult to measure the cloud density from spectral signals alone. Modeling travelling-wave rf diagnostics is very hard because of the large range of spatial and temporal scales that must be resolved to simulate spectra. New numerical models have been used to generate synthetic spectra for electron clouds when the cloud density is not changing, and results have been compared to theoretical results. Here we use dielectric models to generate spectra for clouds that evolve over many bunch crossings. We first perform detailed simulations of cloud buildup using kinetic particle models, and then use an equivalent plasma dielectric model corresponding to this density, at a finer time resolution, to compute spectra. The stability and accuracy of dielectric models that spectra can be accurately determined in these very long timescale simulations.

MOPWO071	Coherent Electron Cooling: Status of Single-Pass Simulations	simulation, FEL, ion, bunching	1049
	B.T. Schwartz, G.I. Bell, I.V. Pogorelov, S.D. Webb Tech-X, Boulder, Colorado, USA D.L. Bruhwiler CIPS, Boulder, Colorado, USA Y. Hao, V. Litvinenko, G. Wang BNL, Upton, Long Island, New York, USA S. Reiche PSI, Villigen PSI, Switzerland
	Funding: US DOE Office of Science. Contracts DE-FC02-07ER41499, DE-FG02-08ER85182, DE-AC02-05CH11231. Advances in nuclear physics depend on experiments that employ relativistic hadron accelerators with dramatically increased luminosity. Current methods of increasing hadron beam luminosity include stochastic cooling and electron cooling; however, these approaches face serious difficulties at the high intensities and high energies proposed for eRHIC . Coherent electron cooling promises to cool hadron beams at a much faster rate. A single pass of an ion through a coherent electron cooler involves the ion's modulating the charge density of a copropagating electron beam, amplification of the modulated electron beam in a free-electron laser, and energy correction of the ion in the kicker section. Numerical simulations of these three components are underway, using the parallel Vorpal framework and Genesis 1.3, with careful coupling between the two codes. Here we present validations of two components of the simulations: Adding bunching to an electron beam at the start of an FEL, and the time-dependent charge density modulation in the kicker. http://www.bnl.gov/cad/eRHIC/ ** V.N. Litvinenko and Y.S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009).

MOPWO077	Design of the Proposed Low Energy Ion Collider Ring at Jefferson Lab	ion, booster, collider, interaction-region	1058
	E.W. Nissen, F. Lin, V.S. Morozov, Y. Zhang JLAB, Newport News, Virginia, USA
	Funding: Supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. The polarized Medium energy Electron-Ion Collider (MEIC) envisioned at Jefferson Lab will cover a range of center-of-mass energies up to 65 GeV. The present MEIC design could also allow the accommodation of low energy electron-ion collisions (LEIC) for additional science reach. This paper presents the first design of the low energy ion collider ring which is converted from the large ion booster of MEIC. It can reach up to 25 GeV energy for protons and equivalent ion energies of the same magnetic rigidity. An interaction region and an electron cooler designed for MEIC are integrated into the low energy collider ring, in addition to other required new elements including crab cavities and ion spin rotators, for later reuse in MEIC itself. A pair of vertical chicanes which brings the low energy ion beams to the plane of the electron ring and back to the low energy ion ring are also part of the design.

MOPWO078	A Harmonic Kicker Scheme for the Circulator Cooler Ring in the Medium Energy Electron-ion Collider	kicker, ion, collider, FEL	1061
	E.W. Nissen, A. Hutton, A.J. Kimber JLAB, Newport News, Virginia, USA
	Funding: Supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. The current electron cooler design for the proposed Medium Energy Electron-Ion collider (MEIC) at Jefferson Lab utilizes a circulator ring for reuse of the cooling electron bunch up to 100 times to cool the ion beams. This cooler requires a fast kicker system for injecting and extracting individual bunches in the circulator ring. Such a kicker must work at a high repetition rate, up to 7.5 to 75 MHz depending on the number of turns in the recirculator ring. It also must have a very short rise and fall time (of order of 1 ns) such that it will kick an individual bunch without disturbing the others in the ring. Both requirements are orders of magnitude beyond the present state-of-the-art as well as the goals of other on-going kicker R&D programs such as that for the ILC damping rings. In this paper we report a scheme of creating this fast, high repetition rate kicker by combining RF waveforms at multiple frequencies to create a kicker waveform that will, for example, kick every eleventh bunch while leaving the other ten unperturbed. We also present a possible implementation of this scheme as well as discuss its limitations.

MOPWO080	GPU-optimized Code for Long-term Simulations of Beam-beam Effects in Colliders	simulation, luminosity, collider, damping	1064
	Y. Roblin, V.S. Morozov, B. Terzić JLAB, Newport News, Virginia, USA M. Aturban, D. Ranjan, M. Zubair ODU CS, Norfolk, USA
	Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177. We report on the development of the new code for long-term simulation of beam-beam effects in particle colliders. The underlying physical model relies on a matrix-based arbitrary-order symplectic particle tracking for beam transport and the Bassetti-Erskine approximation for beam-beam interaction. The computations are accelerated through a parallel implementation on a hybrid GPU/CPU platform. With the new code, a previously computationally prohibitive long-term simulations become tractable. We use the new code to model the proposed medium-energy electron-ion collider (MEIC) at Jefferson Lab.

MOPWO081	The Scheme of Beam Synchronization in MEIC	ion, collider, proton, SRF	1067
	Y. Zhang, Y.S. Derbenev, A. Hutton JLAB, Newport News, Virginia, USA
	Funding: Supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. Synchronizing colliding beams at single or multiple collision points is a critical R&D issue in the design of a medium energy electron-ion collider (MEIC) at Jefferson Lab. The path-length variation due to changes in the ion energy, which varies over 20 to 100 GeV, could be more than several times the bunch spacing. The scheme adopted in the present MEIC baseline is centered on varying the number of bunches (i.e., harmonic number) stored in the collider ring. This could provide a set of discrete energies for proton or ions such that the beam synchronization condition is satisfied. To cover the ion energy between these synchronized values, we further propose to vary simultaneously the electron ring circumference and the frequency of the RF systems in both collider rings. We also present in this paper the requirement of frequency tunability of SRF cavities to support the scheme.

MOPWO083	LEIC - A Polarized Low Energy Electron-ion Collider at Jefferson Lab	ion, collider, booster, proton	1070
	Y. Zhang, Y.S. Derbenev, A. Hutton, G.A. Krafft, R. Li, F. Lin, V.S. Morozov, E.W. Nissen, R.A. Rimmer, H. Wang, S. Wang, B.C. Yunn, H. Zhang JLAB, Newport News, Virginia, USA M.K. Sullivan SLAC, Menlo Park, California, USA
	Funding: Supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357. A polarized electron-ion collider is envisioned as the future nuclear science program at JLab beyond the 12 GeV CEBAF. Presently, a medium energy collider (MEIC) is set as an immediate goal with options for a future energy upgrade. A comprehensive design report for MEIC has been released recently. The MEIC facility could also accommodate electron and proton/ion collisions in a low CM energy range, covering proton energies from 10 to 25 GeV and ion energies with a similar magnetic rigidity, for additional science reach. In this paper, we present a conceptual design of this low energy collider, LEIC, showing its luminosity can reach above 10³³ cm^-2s⁻¹. The design specifies that the large booster of the MEIC is converted to a low energy ion collider ring with an interaction region and an electron cooler integrated into it. The design provides options for either sharing the detector with the MEIC or a dedicated low energy detector in a third collision point, with advantages of either a minimum cost or extra detection parallel to the MEIC operation, respectively. The LEIC could be positioned as the first and low cost phase of a multi-stage approach to realize the full MEIC.

MOPWO088	Semi-analytical Description of the Modulator Section of the Coherent Electron Cooling	plasma, shielding, hadron, simulation	1082
	A. Elizarov, V. Litvinenko BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. We discuss the theoretical description of the modulator section of the coherent electron cooling (CeC), the modern realization of the stochastic electron cooling, where the electron beam serves as a modulator and a kicker, i.e., it records the information about the hadron beam via electron density perturbations resulting from the shielding of the hadrons and then accelerates or decelerates hadrons by its electric field with respect to their velocities. To analyze the performance of the CeC shielding of a hadron in an electron beam should be computed with high precision. We propose a solution of this problem via Fourier and Laplace transforms for 1D, 2D and 3D plasmas. In some cases there are fully analytical solutions, which gave an opportunity to test semi-analytical ones involving numerical evaluations of the inverse integral transforms. Having its own practical value this solution will also serve as a testing ground for our general solution via numerical treatment of the integral equations applicable for the realistic case of the finite beam. V. N. Litvinenko, Y. S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009). ** A. Elizarov, V. Litvinenko, G. Wang, IPAC'12 Proceedings, weppr099 (2012).

TUYB102	Summary of the ILC R&D and Design	positron, linac, damping, cavity	1101
	B.C. Barish CALTECH, Pasadena, California, USA
	This talk should provide a summary of the main activities of ILC-GDE since 2005, and an overview of the Technical Design Report with prospects for the next steps for the future.
	Slides TUYB102 [6.544 MB]

TUOCB101	Argonne Wakefield Accelerator (AWA): A Facility for the Development of High Gradient Accelerating Structures and Wakefield Measurements	wakefield, acceleration, linac, gun	1111
	M.E. Conde, S.P. Antipov, D.S. Doran, W. Gai, C.-J. Jing, R. Konecny, W. Liu, J.G. Power, E.E. Wisniewski, Z.M. Yusof ANL, Argonne, USA S.P. Antipov, C.-J. Jing, R. Konecny Euclid TechLabs, LLC, Solon, Ohio, USA E.E. Wisniewski, Z.M. Yusof Illinois Institute of Technology, Chicago, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357. The recently upgraded AWA facility is being commissioned. Operation of the new L-Band RF gun with a Cesium Telluride photocathode will generate long electron bunch trains, with high charge per bunch (up to 100 nC). The six new linac tanks will boost the beam energy to 75 MeV, making it an extremely well suited drive beam to excite wakefields in structures. One of the main goals of the facility is to generate RF pulses with GW power levels, corresponding to accelerating gradients of hundreds of MV/m and energy gains on the order of 100 MeV per structure. A key aspect of the studies and experiments carried out at the AWA facility is the use of relatively short RF pulses (15 – 25 ns), which is believed to mitigate the risk of breakdown and structure damage.

Paper

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MOYBB101

Review of Laser Wakefield Accelerators

laser, plasma, injection, wakefield

11

V. Malka
LOA, Palaiseau, France

Funding: European Research Council for funding the PARIS ERC project (Contract No. 226424). EC FP7 LASERLABEUROPE/ LAPTECH (Contract No. 228334) EuCARD/ANAC, EC FP7 (Contract No. 227579)
This review talk will highlight the tremendous evolution of the research on laser wakefield accelerators* that has, in record time, led to the production of high quality electron beams beyond the GeV level, using compact laser systems. I will describe the path we followed to explore different injection schemes (bubble, colliding laser pulses, injection in gradient, longitudinal and transverse, ionisation injection) and I will present the most significant breakthroughs which allowed to generate stable, high peak current and high quality electron beams, with control of the charge, of the relative energy spread and of the electron energy. Modelling and experimental results will be as well reported with examples of applications**.
* V. Malka, Physics of Plasmas 19, 055501 (2012)
** V. Malka et al., Nature Physics 4, 447 (2008)

Slides MOYBB101 [14.550 MB]

MOYCB101

Brightness and Coherence of Synchrotron Radiation and FELs

radiation, brightness, FEL, undulator

16

Z. Huang
SLAC, Menlo Park, California, USA

Essential properties of radiation from storage rings and FELs include spatial- and temporal beam brightness and coherence. Starting from a fundamental representation of the electron beam as a radiating source the electromagnetic power can be represented as modes in phase-space to characterize beam quality. For storage rings, conditions for transverse coherence are possible which can lead to high-resolution imaging under a variety of polarization conditions. For FELs the radiation brightness is over 10 orders of magnitude higher with finite temporal coherence times and much of the total FEL power contained in the dominant mode. This presentation should provide an overview of the above.

Slides MOYCB101 [9.731 MB]

MOZB102

Undulator Technologies for Future Free Electron Laser Facilities and Storage Rings

undulator, vacuum, radiation, wiggler

26

M.-E. Couprie
SOLEIL, Gif-sur-Yvette, France

Insertion devices (undulators and wigglers) are key components for high brightness third generation synchrotron sources and for the amplifying medium of free electron lasers. Different technological developments carried out worldwide lead to improved undulator performance. In particular, the advances concerning the in vacuum permanent magnet systems, in particular for short period ones with the operation at cryogenic temperature with NdFeB or PrFeB magnets or for long period ones where in vacuum wigglers will be described. Secondly, progress in Elliptical Polarised Undulators (EPU) will be discussed, such as the DELTA undulator. Recent progress in superconducting undulators will also be reported. Finally, the effect of the insertion devices on the light source operation is analysed, either with the strategies to compensate unwanted effects or in viewing taking advantage of them as for Robinson or damping wigglers for reducing storage ring horizontal emittance.

Slides MOZB102 [8.940 MB]

MOZB201

Overview of the LHeC Design Study at CERN

lepton, linac, luminosity, proton

40

O.S. Brüning
CERN, Geneva, Switzerland

The LHeC is a potential future lepton-hadron collider project at CERN based on the existing LHC infrastructure. The presentation highlights the main results of the recently published conceptual design report, including the findings of an international review committee that evaluated it. The presentation outlines the planed future studies and R&D activities for the next years.

Slides MOZB201 [11.894 MB]

MOPEA004

Beam Lifetime in the ASTRID and ASTRID2 Synchrotron Light Sources: Excitations and Vacuum Dependences

synchrotron, vacuum, ion, emittance

67

J.S. Nielsen, N. Hertel, S.P. Møller
ISA, Aarhus, Denmark

The beam lifetime is a very important parameter for synchrotron light sources without top-up, and sometimes more important than the lowest possible vertical beam emittance. At the ASTRID synchrotron light source, we have for many years routinely applied a phase modulation of the accelerating RF field, together with a vertical excitation of the beam at the first vertical betatron frequency. These two effects increase the beam lifetime from about 3 hours to more than 100 hours at 150 mA. Lifetime measurements as function of modulation and excitation parameters will be presented. Additionally, measurements of the beam lifetime in ASTRID and ASTRID2 as function of vacuum pressure will be presented.

MOPEA012

Lifetime Studies at Metrology Light Source and ANKA

cavity, optics, scattering, septum

88

T. Goetsch, J. Feikes, M. Ries, G. Wüstefeld
HZB, Berlin, Germany
A.-S. Müller
KIT, Karlsruhe, Germany

The Metrology Light Source (MLS)*, situated in Berlin (Germany) is an electron storage ring operating from 10⁵ MeV to 630 MeV and is serving as the national primary radiation source standard from the near infrared to the vacuum ultraviolet spectral region. In its standard user mode, the lifetime is dominated by the Touschek effect. Measurements and analysis of the Touschek lifetime as a function of beam current and RF-Voltage will be presented and compared to measurements done at the ANKA electron storage ring (Karlsruhe, Germany) which operates at 0.5 to 2.5 GeV**.
* R. Klein et al., Phys. Rev. ST-AB 11, 110701 (2008)
** A.-S. Müller et al., Energy Calibration Of The ANKA Storage Ring, In Proceedings of EPAC 2004

MOPEA013

Radioactive Beam Accumulation for a Storage Ring Experiment with an Internal Target

target, ion, injection, kicker

91

F. Nolden, C. Dimopoulou, R. Grisenti, C.M. Kleffner, S.A. Litvinov, W. Maier, C. Peschke, P. Petri, U. Popp, M. Steck, H. Weick, D.F.A. Winters, T. Ziglasch
GSI, Darmstadt, Germany

A radioactive ⁵⁶Ni beam was successfully accumulated for an experiment with an internal hydrogen target at the storage ring ESR of GSI, Germany. The radioactive beam was produced and separated at the GSI fragment separator from a stable ⁵⁸Ni beam. About 6·10⁴ ⁵⁶Ni ions were injected into the ESR on a high relative momentum orbit. The beam was subjected to stochastic cooling, bunched and transported to a low relative momentum orbit where it was neither disturbed by the field of the partial aperture injection kicker nor by the fields of the stochastic cooling kickers. Slightly below this deposition momentum, the beam was accumulated and continuously cooled by means of electron cooling. For each experiment with internal hydrogen target, about 80 shots were injected consecutively, leading to a stored beam of roughly 5·10⁶ particles.

MOPEA014

Temporal and Spectral Observation of Laser-induced THz Radiation at DELTA

laser, radiation, storage-ring, simulation

94

P. Ungelenk, H. Huck, M. Huck, M. Höner, S. Khan, R. Molo, A. Schick
DELTA, Dortmund, Germany
N. Hiller, V. Judin
KIT, Karlsruhe, Germany

Funding: Work supported by the DFG, the BMBF, the Federal State NRW, the Initiative and Networking Fund of the Helmholtz Association, and the German Federal Ministry of Education and Research.
Coherent THz pulses caused by a laser-induced density modulation of the electron bunches are routinely produced and observed at DELTA, a 1.5 GeV synchrotron light source operated by the TU Dortmund University. New measurements performed with a fast hot-electron bolometer allow insight into the turn-by-turn evolution of these pulses. Furthermore, first results from a Fourier transform infrared spectrometer, which is currently under commissioning, are presented.

MOPEA015

A Transverse Electron Target for Heavy Ion Storage Rings

target, ion, interaction-region, storage-ring

97

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

A transverse electron target is a well suited concept under discussion for storage rings to investigate electron-ion interaction processes relevant for heavy ion accelerators. Using a sheet beam of free electrons in crossed beam geometry promises not only a high energy resolution but also allows access to the interaction region for photon and electron spectroscopy under large solid angles. To realize a compact and multi-purpose applicable design, only electrostatic fields are used for beam focussing. The produced electron beam has a length of 10cm in ion beam direction and a width of around 5mm in the interaction region with densities of ~10⁹electrons/cm³. The target geometry allows the independent adjustment of the electron beam current and energy in the region of several 10eV and a few keV. The setup meets the high requirements for an operation in the UHV environment of a storage ring and is installed applying the so-called animated beam technique. The electron target is dedicated to the FAIR storage rings. First measurements have been performed at a test bench. An overview of the project status will be presented including first results of the characterization measurements.

MOPEA017

Electron Cooling of Heavy Ions Interacting with Internal Target at HESR of FAIR

target, emittance, ion, scattering

103

T. Katayama, M. Steck
GSI, Darmstadt, Germany
R. Maier, D. Prasuhn, H. Stockhorst
FZJ, Jülich, Germany

The High Energy Storage Ring (HESR) is designed and optimized to accumulate and store the anti-proton beam for the internal target experiment. The recent demand of atomic physics has impacted to use the HESR facility also as the storage ring of bare heavy ions. In this concept the bare heavy ions are injected at 740 MeV/u from the Collector Ring where the ions are well stochastically cooled to be matched with HESR ring acceptance. In the HESR the 2 MeV electron cooler is prepared with the maximal electron current of 3 A and the cooling length of 2.7 m. The electron cooling process of typically ²³⁸U⁹²⁺ beam is simulated for the Hydogen and Xe internal target with simultaneous use of barrier voltage to compensate the mean energy loss caused by the interaction with internal target. In the present report the detailed simulation results of 6D phase space obtained by the particle tracking code are precisely discussed.

MOPEA020

Comparison of Different Approaches to Determine the Bursting Threshold at ANKA

radiation, synchrotron, storage-ring, synchrotron-radiation

112

P. Schönfeldt, N. Hiller, V. Judin, A.-S. Müller, M. Schwarz, J.L. Steinmann
KIT, Karlsruhe, Germany

The synchrotron light source ANKA at the Karlsruhe Institute of Technology provides a dedicated low-α-optics. In this mode bursting of Coherent Synchrotron Radiation (CSR) is observed for bunch charges above a threshold that depends on beam parameters. This threshold can be determined by several approaches, e.g. bunch lengthening or changes in the THz radiation spectra. This paper compares different methods and their implementation at the ANKA storage ring outlining their advantages, disadvantages and limitations, including reliability and possibility of real time analysis.

MOPEA021

Status of the HESR Electron Cooler Test Set-up

simulation, cathode, controls, vacuum

115

M.W. Bruker, K. Aulenbacher, J. Dietrich, S. Friederich, A. Hofmann, T. Weilbach
HIM, Mainz, Germany
K. Aulenbacher
IKP, Mainz, Germany

For the proposed High Energy Storage Ring (HESR) at FAIR, it is foreseen to install an electron cooling device with a beam current of 3 A and a beam energy of 8 MeV. A test set-up was built at Helmholtz-Insitut Mainz (HIM) to conduct a feasibility study. One of the main goals of the test set-up is to evaluate the gun design proposed by TSL (Uppsala) with respect to vacuum handling, EM fields and the resulting beam parameters. Another purpose of the set-up is to achieve an energy recuperation efficiency of 1 - 10^-5. To measure this quantity, a Wien filter has to be employed, which will also prove capable of mitigating collection losses. The current status of the project will be presented.

MOPEA022

Beam Profile Measurement for High Intensity Electron Beams

laser, scattering, photon, diagnostics

118

T. Weilbach, K. Aulenbacher, M.W. Bruker
HIM, Mainz, Germany
K. Aulenbacher
IKP, Mainz, Germany

Recent developments in the field of high intensity electron beams in the regime below 10 MeV, e.g. energy recovery linacs or magnetized high energy electron coolers, have led to special demands on the beam diagnostics. Since commonly used diagnostic tools like synchrotron radiation and scintillation screens are ineffective or not able to withstand the beam power without being damaged, new methods are needed. Hence a beam profile measurement system based on beam induced fluorescence (BIF) was built. This quite simple system images the light generated by the interaction of the beam with the residual gas onto a PMT. A more elaborated system, the Thomson Laser Scanner (TLS) - the non-relativistic version of the Laser Wire Scanner - is proposed as a method for non-invasive measurement of all phase space components, especially in the injector and merger parts of an ERL. Both methods are implemented in a 100 keV photo gun. Beam profile measurements with BIF as well as first results of the TLS will be presented.

MOPEA026

X-ray Powder Diffraction Beamline for the Iranian Light Source Facility

photon, synchrotron, focusing, brilliance

130

H. Khosroabadi, S. Amiri, H. Ghasem, A. Gholampour
ILSF, Tehran, Iran
H. Ghasem
IPM, Tehran, Iran

Iranian Light Source Facility (ILSF) project has been initiated since 2010 in order to design and construction of a synchrotron facility in Iran. In parallel with the machine’s activities, scientific committee, users community and beamline technical group are working on different aspects of the scientific and beamline design issues for the operating phase after construction*. X-ray powder diffraction beamline is one of the most priorities in ILSF due to wide range of applications and big potential user community in Iran. Conceptual design report of this beamline operating in other worldwide synchrotrons have been studied and compared in details. The light source and schematic design of the beamline has been prepared in this study. Then, the parameters have been calculated and have been optimized by employing computational software such as XOP and SHADOW**. The optical properties of the optical elements such as reflectivity, absorbance, Bragg diffraction, rocking curve, aberration, etc have been studied at this design, and the results have been compared with the other published results. The outcome and final results of this design progress will be discussed in details.
References:
* Conceptual Design Report (2011, summer), ILSF, http://ilsf.ipm.ac.ir/.
** http://www.esrf.eu/UsersAndScience/Experiments/TBS/SciSoft/xop2.3.

MOPEA038

Coherent Wiggler Radiation of Picosecond CW Electron Beam Produced by DC-SRF Photoinjector

wiggler, radiation, SRF, acceleration

160

S. Huang, J.E. Chen, S. Chen, K.X. Liu, S.W. Quan, Zh.W. Wang, X.D. Wen, F. Zhu
PKU, Beijing, People's Republic of China

The DC-SRF photoinjector at Peking University is capable of providing CW electron beam with the energy of 3-5 MeV. The beam has high repetition rate, picosecond bunch length and high quality, which can be used to produce high repetition rate THz wave by wiggler radiation. Through off-crest acceleration, electron beam from the injector may be bunched, which will lead to coherent enhancement of the radiation power. With current setup of the DC-SRF injector and a 10-period wiggler, THz radiation power of 10s mW to a few watts can be achieved within the wavelength range of 200 μm to 500 μm. In this work, we will present the calculation results about THz radiation produced by the electron beam from DC-SRF photoinjector. The preparation for the experiments will be also described.

MOPEA040

Study of Geometry Dependent Multipacting of a Superconducting QWR

accelerating-gradient, simulation, cavity, vacuum

166

K. Zhou, X.Y. Lu, X. Luo, S.W. Quan, L. Yang, Z.Y. Yao
PKU, Beijing, People's Republic of China

Funding: The Major Research Plan of National Natural Science Foundation of China
A superconducting quarter wave resonator (QWR) of frequency=162.5 MHz and β=0.085 has been designed at Peking University. This paper focus on the multipacting (MP) study for the QWR with CST Particle Studio. The simulation results for the initial designed model reveal that there is no sign of MP with its normal operating accelerating gradients in the range of 6-8 MV/m. The accelerating gradient range that may incur MP is from about 1.4 MV/m to 3.2 MV/m, and the places where MP may be encountered are mainly located at the top part of the QWR. So the effect of different top geometries on MP has also been studied in depth. Our results show that inward convex round roof is better than other round roofs, and plane roofs have an obvious advantage over round roofs on the suppression of MP in general. While considering the optimization of its electromagnetic (EM) design, our initial designed model is also acceptable.

MOPEA043

Transverse Instabilities of Two Twisted Beams in a Storage Ring

ion, storage-ring, simulation, kicker

172

B.C. Jiang, M.Z. Zhang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
G.X. Xia
UMAN, Manchester, United Kingdom

Two twisted beams (two beams run on the different closed orbit) in a storage ring which is produced by fast kickers can potentially deliver two bunds of radiations through one insertion device or one bend magnet, in this way doubles the beam line stations. This operation mode needs higher beam current and more RF buckets to be filled to keep the brightness comparable to the single beam operation mode. The resistive wall instability and ion trapping effects is analysed to address the higher current operation possibility. The analyze results show that twisted beams can weaken those two instabilities.

MOPEA056

Measuring and Improving the Momentum Acceptance and Horizontal Acceptance at MAX III

cavity, lattice, vacuum, storage-ring

205

A. Hansson, Å. Andersson, J. Breunlin, G. Skripka, E.J. Wallén
MAX-lab, Lund, Sweden

Lifetime measurements for varying horizontal scraper positions performed at different RF frequencies suggested a horizontal aperture restriction in the MAX III synchrotron light source. A combination of local orbit distortions and horizontal scraper measurements pinpointed the location of the horizontal aperture restriction to the center of the main cavity straight section. The aperture restriction was determined to be located 10.4 ± 0.3 mm from the beam center. The precise result was achieved by measurements and calculations of the Touschek lifetime as a function of the main cavity voltage. Realignment of the main cavity increased the average lattice momentum acceptance from 0.0116 ± 0.0003 to 0.0158 ± 0.0003 and the horizontal acceptance from 26 ± 2 × 10^-6 m to larger than 44 ± 2 × 10^-6 m. The increase in momentum acceptance increased the lifetime in MAX III by a factor of two.

MOPEA057

Studies of the Electron Beam Lifetime at MAX III

scattering, cavity, vacuum, emittance

208

A. Hansson, Å. Andersson, J. Breunlin, G. Skripka, E.J. Wallén
MAX-lab, Lund, Sweden

MAX III is a 700 MeV 3rd generation synchrotron light source located at the MAX IV Laboratory in Sweden. The lifetime in the storage ring is lower than originally envisaged. From vertical scraper measurements the lifetime contributions at 300 mA stored current have been determined. The lifetime is mainly limited by the Touschek lifetime, which is lower than its design value, whereas the vacuum lifetime is close to the expected value. The low Touschek lifetime is explained by a lower than design emittance ratio and momentum acceptance in the storage ring.

MOPEA063

The First Results of the NESTOR Commissioning

injection, storage-ring, dipole, focusing

225

A.Y. Zelinsky, V.P. Androsov, O. Bezditko, V.N. Boriskin, P. Gladkikh, A.N. Gordienko, V.A. Grevtsev, A. Gvozd, V.E. Ivashchenko, A.A. Kalamayko, I.I. Karnaukhov, I.M. Karnaukhov, D. Korzhov, V.P. Kozin, V.A. Kushnir, V.P. Lyashchenko, M.P. Maksim, V.S. Margin, N.I. Mocheshnikov, V.V. Mytrochenko, A. Mytsykov, F.A. Peev, O.V. Ryezayev, V.P. Sergienko, A.A. Shcherbakov, S. Sheyko, V.L. Skirda, Y.N. Telegin, V.I. Trotsenko, O.P. Zolochevskij, O.D. Zvonarjova
NSC/KIPT, Kharkov, Ukraine

In the paper the first results of the NESTOR facility are presented. 60 MeV electron linac injector has been tested and the first electron beam with project parameters was registered at the screen monitors. Electron beam was passed through the transportation channel and injection system. As a result, the first turn of the storage ring was closed.

MOPEA065

Commissioning of the Ion Source for Siemens Novel Electrostatic Accelerator

ion, plasma, ion-source, extraction

231

H. von Jagwitz-Biegnitz
JAI, Oxford, United Kingdom
P. Beasley, O. Heid
Siemens AG, Erlangen, Germany
D.C. Faircloth
STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
A.J. Holmes
Marcham Scientific Ltd, Hungerford, United Kingdom
R.G. Selway
Inspired Engineering Ltd, Climping, United Kingdom
B. Singh, E. Zitvogel
BNL, Upton, New York, USA

Siemens is developing a novel compact DC electrostatic tandem accelerator and currently building a prototype. A dedicated H⁻ ion source for this accelerator has been designed and built. This paper reports on some of the design features as well as results of the commissioning phase of this filament driven DC multicusp volume H⁻ ion source. Stable H⁻ currents of more then 300 μA at 10 keV have been extracted. This satisfies the beam current requirement of the novel accelerator.

MOPEA070

Operating the Diamond Light Source in Low Alpha Mode for Users

injection, lattice, factory, optics

246

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

Since its first introduction in April 2009, the low alpha operational mode has been continually refined in order to best meet the needs of the user community. Initially the optics were used only to generate short x-ray pulses, for which a stable, low emittance, single bunch was requested, with the emphasis placed on increased bunch charge over shortest absolute pulse duration. More recently, the optics have been adapted to enhance the CSR gain in the THz region of the electromagnetic spectrum. In this paper we summarise the work carried out in order to meet these two demands.

MOPEA077

Accelerator Physics and Light Source Research Program at Duke University

FEL, wiggler, storage-ring, feedback

264

Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
he accelerator physics and light source research program at Duke Free-Electron Laser Laboratory (DFELL), TUNL, is focused on the development of the storage ring based free-electron lasers (FELs), and a state-of-the-art Compton gamma-ray source, the High Intensity Gamma-ray Source (HIGS). Driven by the storage ring FEL, the HIGS is world's most intense Compton gamma-ray source with a maximum total flux of few 10¹⁰ gamma per second (around 10 MeV). Operated in the energy range from 1 to 100 MeV, the HIGS is a premier nuclear physics research facility in the world. In 2012, we completed a major accelerator upgrade project with a wiggler switchyard system which allows the configuration changes between planar and helical FEL wigglers, and a great enhancement of the FEL gain when operated with 3 or 4 helical wigglers. In this paper, we will describe our ongoing light source development to produce gamma-ray beams in the new energy range of 100 and 158 MeV. We will also provide a summary of our accelerator physics research activities in the area of nonlinear dynamics, beam instability research, and FEL research.

MOPEA083

Energy Modulation in Coherent Electron Cooling

ion, plasma, FEL, simulation

276

G. Wang, M. Blaskiewicz, V. Litvinenko
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Coherent electron cooling (CeC) relies on Debye shielding to imprint information of the ion beam to an electron beam [1]. Apart from the density modulation, Debye shielding also modulates the energy of electrons, which provides additional seeding for the free electron laser (FEL) amplifier. In this work, we show that the energy modulation of a longitudinal slice of the electrons, induced by dynamic Debye shielding of a moving ion in anisotropic electron plasma with κ-2 velocity distribution, can be expressed into a 1D integral. The results are then applied to the 1D FEL model to investigate the effects of energy modulation to the correcting force in the kicker.
[1] V.N. Litvinenko, Y.S. Derbenev, Coherent Electron Cooling, Physical Review Letters, 102 (2009) 114801. http://link.aps.org/abstract/PRL/v102/e114801

MOPFI001

Characterization of a Superconducting Pb Photocathode in a SRF Gun Cavity

cathode, laser, gun, cavity

279

R. Barday, T. Kamps, O. Kugeler, A. Neumann, M. Schmeißer, J. Völker
HZB, Berlin, Germany
P. Kneisel
JLAB, Newport News, Virginia, USA
R. Nietubyć
NCBJ, Świerk/Otwock, Poland
J.K. Sekutowicz
DESY, Hamburg, Germany
J. Smedley
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Bundesministerium für Bildung und Forschung and Land Berlin. The Pb deposition activity is supported by EuCARD.
Photocathodes are a limiting factor for the next generation of ultra-high brightness photoinjector driven accelerators. We studied the behavior of a superconducting Pb cathode in the cryogenic environment of a superconducting rf gun cavity related to the quantum efficiency, its spatial distribution and the work function. Cathode surface contaminations can modify the performance of the photocathodes as well as the gun cavity. We discuss the possibilities to remove these contaminations.

MOPFI005

XPS and UHV-AFM Analysis of the K2CsSb Photocathodes Growth

cathode, vacuum, background, factory

291

S.G. Schubert
HZB, Berlin, Germany
I. Ben-Zvi, M. Ruiz-Osés
Stony Brook University, Stony Brook, USA
X. Liang
SBU, Stony Brook, New York, USA
H.A. Padmore, T. Vecchione
LBNL, Berkeley, California, USA
T. Rao, J. Smedley
BNL, Upton, Long Island, New York, USA

Funding: This work is funded by the Department of Energy, under Contract No. KC0407-ALSJNT-I0013, DE-SC0005713, the Bundesministerium für Bildung und Forschung (BMBF) and the state of Berlin, Germany.
Next generation light sources, based on Energy Recovery Linac and Free Electron Laser technology will rely on photoinjector based electron sources. Successful operation of such sources requires reliable photocathodes with long operational life, uniform and high quantum efficiency, low thermal emittance and low dark current. The goal of this project is to construct a cathode which meets these requirements. Advances in photocathode research must take a combined effort. The materials have to be analyzed by means of chemical composition, surface structure and these findings have to be correlated to the quantum efficiency and performance in the injector. The presented work focuses on the chemical composition and surface structure of K2CsSb photocathodes. The XPS and AFM measurements were performed at the Center of Functional Nanomaterials at BNL. K2CsSb photocathodes were grown under UHV conditions. The components were adsorbed one at a time and after each growth step the corresponding XPS spectra was taken. During growth the quantum efficiency was recorded. As last step the sample was moved into the AFM without exposure to air to determine the surface roughness.

MOPFI006

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

polarization, vacuum, laser, ion

294

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

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

MOPFI011

Construction and First Tests of the New Injection System for the Linac II at DESY

linac, gun, injection, positron

303

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

For the Linac II, which supplies the accelerator chain at DESY with electrons and positrons, a new injection system is planned. It is supposed to ensure reliable operation and to avoid the beam loss of about 60% at energies up to 400 MeV and the associated activation. The function of the injector components, the entire injection system and the acceleration in the linac sections were optimized in simulations. The main components are a 6 A/100 kV triode gun, buncher and a dispersive section for energy collimation. The output energy is 5 MeV and the beam pulse length can be chosen from 5 ns to 50 ns. The new buncher structure is a hybrid of a standing wave and traveling wave structure and allows a compact design and good electron capture. One of two assembled structures has been tuned and completed a test rig in the linac tunnel. In this test system detailed analysis of its properties is in progress as well as minor corrections like alignment and improvements of reliability. The final installation is going to take place from September 2013. First experimental analysis compared to simulation results will be presented.

MOPFI012

Measurement of Adsorption Rates of Residual Gases for NEA-GaAs Surface

cathode, ion, vacuum, emittance

306

M. Kuriki, H. Iijima, K. Miyoshi, K.U. Uchida
HU/AdSM, Higashi-Hiroshima, Japan

A GaAs photocathode activated the surface to negative-electron-affinity (NEA) is an important device for high-average-current electron accelerators such as a next-generation light source based on an energy recovery linac. The NEA surface is normally formed by a yo-yo technique in which cesium and oxygen are applied onto the surface alternately. Although the initial quantum efficiency is relatively larger than that of another cathode, the lifetime is shorter. The degradation with time elapsing even if the electron beam is not extracted is mainly caused by adsorption of residual gases in a vacuum chamber. We have evaluated the adsorption rates of various gases for the NEA surface by measuring the dark lifetime in sample gases such as hydrogen, carbon oxide and carbon dioxide.

MOPFI013

A Lifetime Study of CsK2Sb Cathode

cathode, laser, vacuum, brightness

309

M. Kuriki, H. Iijima, K. Miyoshi, N. Norihito
HU/AdSM, Higashi-Hiroshima, Japan

Funding: Cooperative and Supporting Program for Researches and Educations in　Universities by High energy accelerator research organization (KEK)
CsK2Sb multi-alkali cathode is one of the candidates of robust and high efficiency cathode for high brightness electron source. CsKSb can be driven by green laser and it is a big advantage comparing to Cs2Te cathode which is widely used as a robust photo-cathode and driven by UV light. In Hiroshima University, a test chamber for CsK2Sb photo-cathode study is developed. In the chamber, CsK2Sb photo-cathode is formed by evaporation on SUS base plate. During the evaporation, amount is monitored by quartz meter. We devised good locations of the evaporation source, base plate, and thickness monitor, so that all evaporation processes for Cs, K, and Sb are under control. The base plate temperature is also controlled during the cathode formation. More than 2.0% quantum efficiency was achieved at the first activation test. The cathode lifetime was more than 200 hours and more than 20C in charge. The latest experimental result will be reported.

MOPFI014

A Charge Lifetime Study of NEA GaAs Cathode by Ion Back-bombardment

cathode, ion, vacuum, simulation

312

M. Kuriki
KEK, Ibaraki, Japan
L. Guo, H. Iijima, K. Miyoshi
HU/AdSM, Higashi-Hiroshima, Japan

Funding: Quantum beam project by the Ministry of Education, Culture, Sports, Science and Technology; The title is High Brightness Photon Beam by Laser-Compton Scattering.
NEA GaAs cathode is one of the most important techniques for advanced future projects based on linac. Up to 90% polarized beam can be generated with high quantum efficiency, 0.1 – 10%. The extremely low emittance beam can be generated driven by optimized wavelength laser. Although these remarkable features, the less robustness has been the biggest issue on the real operation of this cathode. According to past experiments, there are three sources of the cathode degradation; gas absorption, thermal desorption, and ion-back bombardment. First two processes could be controlled by less vacuum pressure in order of 10^-10Pa and keeping the cathode temperature low. The ion back-bombardment is the last issue which should be solved for high brightness operation in such as ERL. We observed the cathode quantum efficiency evolution in various laser power density and bias voltage. We found that the cathode degradation was due to the ion back-bombardment quantitatively and the deactivation coefficient of NEA surface by one ion collision did not depend on the bias voltage. We report the experimental results and its analysis based on the ion back-bombardment hypothesis.

MOPFI017

SuperKEKB Positron Source Target Protection Scheme

target, positron, radiation, simulation

315

L. Zang, T. Kamitani
KEK, Ibaraki, Japan

The SuperKEKB requires an intense beam with a large number of positrons, which is generated by a high energy electron beam strike on a solid tungsten target. The cascade shower in the target deposits large amount of energy in the material leading to target damage. The pulsed electron beam distributed the energy non-uniformly over the target. In that case, a mechanical stress appears due to the large thermal gradient during each pulse, which could potentially destroy the target. Based on the analysis of the SLAC damaged target, peak energy deposition density (PEDD) should not exceed 35 J/g to ensure a long term of safe operation. One way of reducing PEDD is increasing the beam spot size. Hence we proposed a target protection scheme, in which a protection target is placed upstream of generation target as a spoiler. The aim is to maintain the generation target’s PEDD below 35 J/g even with a point primary electron beam. In this paper, we will introduce graphite, aluminum and copper as the protection target material candidates. And also present the PEDD and positron yield evaluation as a function of various parameters such as protection target thickness and drift space.

MOPFI019

Beam Generation from a 500 kV DC Photoemission Electron Gun

gun, cathode, laser, high-voltage

321

N. Nishimori, R. Hajima, S.M. Matsuba, R. Nagai
JAEA, Ibaraki-ken, Japan
Y. Honda, T. Miyajima, M. Yamamoto
KEK, Ibaraki, Japan
H. Iijima, M. Kuriki
HU/AdSM, Higashi-Hiroshima, Japan
M. Kuwahara
Nagoya University, Nagoya, Japan

Funding: This work is supported by MEXT Quantum Beam Technology Program and partially supported by JSPS Grants-in-Aid for Scientific Research in Japan (23540353).
The next generation light source such as X-ray FEL oscillator requires high brightness electron gun with megahertz repetition rate. We have developed a DC photoemission electron gun at JAEA for the compact energy recovery linac (cERL) light source under construction at KEK. This DC gun employs a segmented insulator with guard rings to protect the insulator from field emission generated from central stem electrode. We have successfully applied 500-kV on the ceramics with a cathode electrode in place and generated beam from the 500kV DC photoemission gun in October 2012. Details of the beam generation test will be presented.

MOPFI020

Cold Test of the Coaxial Cavity for Thermionic Triode Type RF Gun

cavity, gun, resonance, FEL

324

T. Konstantin, Y.W. Choi, T. Kii, R. Kinjo, K. Masuda, M. Mishima, K. Nagasaki, H. Negm, H. Ohgaki, K. Okumura, M. Omer, S. Shibata, K. Shimahashi, K. Yoshida, H. Zen
Kyoto University, Institute for Advanced Energy, Kyoto, Japan

A thermionic rf gun has several advantages as compared to photocathode gun. Such as low cost, high averaged current and simple operation. However a thermionic rf gun has a significant disadvantage in form of back bombardment effect. The KU-FEL facility is an oscillator type FEL, which uses a thermionic 4.5 cell S-band RF gun for electron beam generation. The back bombardment effect causes increasing current in macropulse, which limits the gain of the FEL. In order to mitigate the current increase we plan to modify thermionic rf gun to triode type rf gun. Therefore an additional rf cavity has been designed. This cavity has separate rf power supply with amplitude and phase control. By this means we can properly adjust the injection of electrons into the main gun body. According to simulations the triode type gun can reduce 80% of back streaming electron energy*. The cold tests of the first prototype have revealed deviation from designed values**. Based on the tests of the first prototype new prototype with integrated mechanism for resonance tuning has been designed and fabricated. In this work we report the cold test of the redesigned prototype of the coaxial rf cavity.
* K. Masuda et al. Proceedings of FEL 2006, BESSY Berlin.
** M. Takasaki et al. Proceedings of FEL 2010, Malbö

MOPFI023

Development of Better Quantum Efficiency and Long Lifetime Iridium Cerium Photocathode for High Charge electron RF Gun

laser, cathode, gun, linac

327

D. Satoh
TIT, Tokyo, Japan
N. Hayashizaki
RLNR, Tokyo, Japan
M. Yoshida
KEK, Ibaraki, Japan

We developed an Ir5Ce photocathode as a high charge electron source for SuperKEKB electron linac. The required electron beam parameters are 5 nC and 10 mm•mrad from the electron gun of the SuperKEKB electron linac. We plan to generate this electron beam using a laser-driven RF gun installed with a photocathode that has a long lifetime and a high-power laser system through more than a year without replacement. Therefore, we focused on the Ir5Ce compound as a new photocathode which has a high melting point (> 2100 K) and a low work function (2.57 eV). The results of measurements showed that the quantum efficiency of Ir5Ce photocathode was 1.0×10^-4 treated by the laser cleaning using the 4nd harmonic of Nd:YAG laser or the heater treatment. Furthermore, its photoemission properties could be maintained for a long term even if its photocathode was in the low vacuum conditions ( ～10^-6 Pa) since the Ir5Ce compound is far less contaminated than other photocathodes. Finally, We have succeed to generate electron beams of 4.4 nC by the Ir5Ce photocathode installed at the 3-2 sector DAW type RF gun and accelerate it through a linac end in KEK electron linac.

MOPFI024

Ultra-short Electron Bunch Generation by an ECC RF Gun

gun, radiation, laser, cathode

330

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

Funding: Work supported by JSPS Grant-in-Aid for Young Scientists (B) 23740203 and Scientific Research (A) 10001690
Energy Chirping Cell attached rf gun (ECC rf gun) is a photocathode rf gun specialized for ultra-short bunch generation. This ECC rf gun has been made with the collaboration of High Energy Accelerator Research Organization (KEK). Although the bunch length could be controlled by the laser pulse width, the bunch length ends up to be more than 1ps due to space charge effect when using a femto-second laser and a normal 1.6 cell cavity. Concerning this phenomenon, ECC is attached right after the 1.6 cell so that the electron bunch would be compressed after the electron bunch is accelerated around 5MeV. The roll of ECC is to chirp the energy with the linear part of the rf electric field. The electron bunch would be compressed by velocity difference as it drifts. Simulation results from PARMELA and GPT show that ECC rf gun can accelerate an 100pC bunch with the bunch length less than 100fs. We already manufactured this ECC rf gun and installed in our system. We demonstrated the ultra-short bunch by measuring the coherent THz light by synchrotron radiation and transition radiation. In this conference, we will report the results of ultra-short bunch generation experiments, and future plans.

MOPFI031

Progress on the Construction of the 100 MeV / 100 kW Electron Linac for the NSC KIPT Neutron Source

linac, neutron, controls, dipole

351

Y.L. Chi, J. Cao, P. Chen, B. Deng, C.D. Deng, D.Y. He, X. He, M. Hou, X.C. Kong, Q. Le, X.P. Li, J. Liu, R.L. Liu, W.B. Liu, H.Z. Ma, G. Pei, S. Pei, H. Song, L. Wang, S.H. Wang, X. Wang, Q. Yang, J. Yue, J.B. Zhao, J.X. Zhao, Z.S. Zhou
IHEP, Beijing, People's Republic of China
M.I. Ayzatskiy, I.M. Karnaukhov, V.A. Kushnir, V.V. Mytrochenko, A.Y. Zelinsky
NSC/KIPT, Kharkov, Ukraine
Y. Gohar
ANL, Argonne, USA

IHEP, China is constructing a 100 MeV / 100 kW electron linac for NSC KIPT, Ukraine. This linac will be used as the driver of a neutron source based on a subcritical assembly. In 2012, the injector part of the linac was pre-installed as a testing facility in the experimental hall #2 of IHEP. The injector beam and key hardware testing results were satisfying. Recently, the injector testing facility was disassembled and all of the components for the whole linac have been shipped to Ukraine from China by ocean shipping. The installation of the whole machine in KIPT will be started in June. The progress on the construction are reported, injector beam and key hardware testing results are presented.

MOPFI032

Electron Emission of the Stripping Foil and Collimation System for CSNS/RCS

proton, collimation, scattering, injection

354

M.Y. Huang, Y.D. Liu, N. Wang, S. Wang
IHEP, Beijing, People's Republic of China

For the Rapid Cycling Synchrotron of the China Spallation Neutron Source (CSNS/RCS), the electron emission plays an important role in the accelerator limitation. The interactions between the proton beam and the stripping foil were studied, and the electron scattering processes were simulated by the ORBIT and FLUKA codes. Then, the electron energy distribution and the electron yielding rate can be given. Furthermore, the interactions between the proton beam and the collimation system were studied, and the electron scattering processes were simulated. Then, the energy distribution of the primary electron emission can be given and the yielding rate of the primary electron can be obtained.

MOPFI034

First Intense H⁻ Beam Generated by a Microwave-driven Pure Volume Source

ion, ion-source, plasma, extraction

360

S.X. Peng, J. Chen, J.E. Chen, Z.Y. Guo, H.T. Ren, Zh.W. Wang, Y. Xu, T. Zhang
PKU, Beijing, People's Republic of China
A.L. Zhang
Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China
J. Zhao
State Key Laboratory of Nuclear Physics and Technology, Beijing, Haidian District, People's Republic of China

The 2.45 GHz Electron cyclotron resonance (ECR) plasma generators have demonstrated their efficiency, reproducibility on producing H⁺, D⁺, O+, N+, He+, Ar+* and He2+ at Peking University(PKU). Recently, modifications on magnet field configuration, discharge chamber structure and extraction system have been done to set-up a microwave-driven pure volume H⁻ ion source. First experiment was done on PKU ion source test bench at the beginning of Nov, 2012. A 15 mA H⁻ ion beam has been produced at 40 keV by this prototype source. This paper describes the source principle and design in detail and reports on the current status of the development work.
* H. T. Ren, S. X. Peng*, P. N. Lu, S. Yan, Q. F. Zhou, J. Zhao, Z. X. Yuan, Z. Y. Guo and J. E. Chen, Rev. Sci. Instrum. 83, 02B905 (2012)

MOPFI036

Study of the Cold Cathode RF Electron Gun Based on Doped Diamond Films at CAEP

gun, cathode, FEL, emittance

366

X. Li
TUB, Beijing, People's Republic of China
W. Bai, M. Li
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

Diamond relevant materials have been considered as a promising field emission cathode in recent years. High current density can be obtained either by diamond field emission arrays or by doped diamond films under electrical strengths of several decades of MV/m. Based on the doped films a half cell S-band electron gun has been designed and constructed at CAEP. The gun can provide an accelerating gradient of 60-80 MV/m on the cathode surface (6 mm in diameter). Simulations have proven good performance of such a gun but it needs confirmed by further experiments. Details of the experiments and comparisons with simulations will be reported.

MOPFI037

Design and Experiment of a Compact C-band Photocathode RF Gun for UED

gun, solenoid, emittance, cathode

369

X.H. Liu, H.B. Chen, W.-H. Huang, C.-X. Tang, Z. Zhang
TUB, Beijing, People's Republic of China

A compact C-band photocathode RF gun for the MeV UED facility is developed in Tsinghua University, which is designed to work at the frequency of 5.712GHz. This paper presents the physics and RF structure design, and beam dynamics optimization of this C-band RF gun. Some new structure design will be adopted in this gun, including the optimized cavity length and elliptical iris, which is helpful to achieve lower emittance and larger mode separation. This paper likewise presents experiment parameters and the cold test results of this C-band RF gun.

MOPFI038

Generation and Measurement of Sub-picosecond Electron Bunch in Photocathode RF Gun

laser, radiation, emittance, acceleration

372

W.W. Li, Z.G. He, R. Huang, Q.K. Jia, G. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

The generation of subpicosecond electron bunch in the photocathode rf gun was considered and simulated by improving the acceleration gradient of the gun, suitably tuning the charge of the electron bunch and the acceleration phase. To measure the length of the electron bunch, the design of a nondestructive bunch length measurement technology was also presented in this paper.

MOPFI039

The Design of a Compact THz Source Based on Photocathode RF Gun

radiation, gun, emittance, space-charge

375

W.W. Li, Z.G. He, R. Huang, Q.K. Jia
USTC/NSRL, Hefei, Anhui, People's Republic of China

Narrow-band THz coherent Cherenkov radiation can be driven by a subpicosecond electron bunch traveling along the axis of a hollow cylindrical dielectric-lined waveguide. We present a scheme of compact THz radiation source based on the photocathode rf gun. On the basis of our analytic result, the subpicosecond electron bunch with high charge (800pC) can be generated directly in the photocathode rf gun. A narrow emission spectrum peaked at 0.24 THz with 2 megawatt (MW) peak power is expected to gain in the proposed scheme (the length of the facility is about 1.2 m), according to the analytical and simulated results.

MOPFI044

VHF Gun Research at SINAP

gun, cavity, FEL, vacuum

380

Q. Gu, L. Chen, W. Fang, G.Q. Lin
SINAP, Shanghai, People's Republic of China

The R&D work on the high power THz based on energy recovery linac (ERL) has been carried out in Shanghai Institute of Applied Physics (SINAP). One of the key components for the ERL is the high brightness electron source. The low frequency gun technology has been adopted, by comparing with the SRF gun and DC gun. In this paper, the design and cold test of a 250MHz gun will be presented.

MOPFI045

Studying of Multipacting in Micro-pulse Electron Gun

gun, simulation, resonance, cavity

383

L. Liao, W. Fang, Q. Gu, M. Zhang, M.H. Zhao
SINAP, Shanghai, People's Republic of China

Depending on the complexity of multipacting phenomenon, more works are focused on the occurrence of multipacting in the micro-pulse electron gun. In this paper, the multipacting resonance condition is determined in a reentrant cavity model of the gun. The resonance parameters work as the input for VORPAL simulations in order to achieve a steady state saturation in the cavity. The simulation results showed that the gun can give rise to electrons beam with high currents and short pulses.

MOPFI057

Studies for the LHeC Beam Transfer Systems

linac, kicker, injection, extraction

410

C. Bracco, B. Goddard
CERN, Geneva, Switzerland

The LHeC would allow for collisions between an electron beam from a new accelerator with the existing LHC hadron beam. Two possible configurations were studied: a separate LINAC (LINAC-ring) or a new electron ring superimposed on the LHC (ring-ring). The racetrack LINAC is now considered as the baseline for the LHeC design, with the ring-ring solution a back up. The studies performed for all the considered options are presented in this paper. For the LINAC-ring option the requirements for the post-collision line and the beam dump design have been evaluated in the cases of a 140 GeV and a 60 GeV electron beam. In the ring-ring option studies have been performed of the optics design of the transfer line from the a 10 GeV injector LINAC into the LHeC ring and of the injection system. The internal 60 GeV electron ring dump design has also been considered.

MOPFI058

Studies of Cs3Sb Cathodes for the CLIC Drive Beam Photoinjector Option

cathode, gun, laser, vacuum

413

I. Martini, E. Chevallay, S. Döbert, V. Fedosseev, C. Heßler, M. Martyanov
CERN, Geneva, Switzerland

Within the CLIC (Compact Linear Collider) project, feasibility studies of a photoinjector option for the drive beam as an alternative to its baseline design using a thermionic electron gun are on-going. This R&D program covers both the laser and the photocathode side. Whereas the available laser pulse energy in ultra-violet (UV) is currently limited by the optical defects in the 4th harmonics frequency conversion crystal induced by the 0.14 ms long pulse trains, recent measurements of Cs3Sb photocathodes sensitive to green light showed their potential to overcome this limitation. Moreover, using visible laser beams leads to better stability of produced electron bunches and one can take advantages of the availability of higher quality optics. The studied Cs3Sb photocathodes have been produced in the CERN photoemission laboratory using the co-deposition technique and tested in a DC gun set-up. The analysis of data acquired during the cathode production process will be presented in this paper, as well as the results of life-time measurements in the DC gun.

MOPFI065

VELA (formerly EBTF) Simulations and First Beam Commissioning

gun, diagnostics, simulation, laser

431

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

VELA (Versatile Electron Linear Accelerator), formerly known as EBTF (Electron Beam Test Facility), at STFC Daresbury Laboratory, is a photoinjector test facility which will provide beam into two user areas for scientific and industrial applications. It is based on a 2.5 cell S-band RF photoinjector driven by a Ti:Sapphire laser. The design is aimed to deliver short bunches at 10-250 pC charge with low transverse emittance. We present beam dynamics simulations of VELA as well as the results from first beam commissioning.

MOPFI066

An Ultra-Low Energy Electron Beam Ion Trap in Shanghai

ion, plasma, injection, cathode

434

J. Xiao, R. Hutton, X. Jin, D. Lu, B. Tu, Y. Yang, R. Zhao, Y. Zou
Fudan University, Shanghai, People's Republic of China

Electron beam ion traps (EBITs) are very useful tools for disentanglement studies of atomic processes in plasmas. In this paper, a new ultra-low energy EBIT, SH-HtscEBIT, is reported. This EBIT can operate in the electron energy range of 30–4000 eV, with a current density of up to 100 A/cm². The low energy limit of this machine is 30 eV, which is the lowest energy among the EBITs around the world. The maximum magnetic field in the central drift tube region of this EBIT is around 0.25 T, produced by a pair of high temperature superconductor coils. This EBIT is set up for the purpose of disentangling spectroscopic studies of edge plasmas relevant to magnetic fusion devices, and of astro-plasmas. All the elements for the spectroscopic studies can be injected through an injection system. Both the design and the performance of this EBIT are presented.

MOPFI068

High Repetition Rate Highly Stable S-band Photocathode Gun for the CLARA Project

gun, cavity, laser, cathode

437

B.L. Militsyn, L.S. Cowie, P. Goudket, S.P. Jamison, J.W. McKenzie, K.J. Middleman, R. Valizadeh, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
V.V. Paramonov
RAS/INR, Moscow, Russia
M.D. Roper
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

Compact Linear Accelerator for Research and Applications (CLARA) is a 250 MeV electron facility which is under development at STFC ASTeC. The CLARA photo-injector is based on a RF photocathode gun operating with metal photocathodes and driven by a third harmonic of Ti: Sapphire laser (266 nm). The injector will be operated with laser pulses with an energy of up to 2 mJ, pulse durations down to 180 fs FWHM and a repetition rate of up to 400 Hz. In order to investigate performance of different photocathodes the gun is equipped with a load-lock system which would allow replacement of the photocathodes. Duration and emittance of electron bunches essentially depends on the mode of operation and vary from 0.1 ps at 20 pC to 5 ps at 200 pC and from 0.2 to 2 mm mrad respectively. Requirements for the stability of beam arrival time at the CLARA experimental area are extremely high and vary from hundreds down to tenths femtoseconds. In the presented article we analyse stability of the guns with 1.5 and 2.5 cell and the beam quality delivered by a gun with coaxial and waveguide coupler and analyse possibility of injection time stabilisation with low level RF and optical feedback system.

MOPFI069

Preparation of the Polycrystalline Copper Photocathodes for the VELA RF Photocathode Gun

plasma, gun, ion, cathode

440

R. Valizadeh, A.N. Hannah, K.J. Middleman, B.L. Militsyn, T.C.Q. Noakes, R.N.C. Santer
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
M.D. Roper
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

The Electron Beam Test Facility (EBTF) is a high performance electron source under commissioning at ASTeC. The photoinjector of the source is based on a S-band photocathode RF gun operating with a copper photocathode which is driven by a third harmonic of Ti: Sapphire laser (266 nm). The photocathode used in the RF gun is an integrated part of the gun cavity which is polycrystalline copper disk, polished to 1um roughness, and is placed at the back wall of the first 0.5 cell in the gun cavity. In order to accomplish a procedure to activate surface prior installation, copper test samples with roughness of 0.1 um were prepared by different techniques. The best results have been obtained by ex-situ plasma cleaning in an oxygen atmosphere. Analyses showed that there was no carbon on the surface and the surface was composed of copper oxide. After heating the sample in-situ to 220 C for almost all the surface oxide was removed. For this surface a QE of 2 x10^-5 was measured. Further heating to higher temperature did not result in any improvement either in surface composition nor a noticeable increase in QE. Prepared such a way operational photocathode is now under commissioning in the gun.

MOPFI071

High Power Cyclotrons for the Neutrino Experiments DAEδALUS and IsoDAR

cyclotron, ion, proton, ion-source

446

R.J. Barlow, A. Bungau, A.M. Kolano
University of Huddersfield, Huddersfield, United Kingdom
A. Adelmann
PSI, Villigen PSI, Switzerland
J.R. Alonso
LBNL, Berkeley, California, USA
W.A. Barletta, A. Calanna, D. Campo, J.M. Conrad
MIT, Cambridge, Massachusetts, USA
L. Calabretta
INFN/LNS, Catania, Italy
F. Méot
BNL, Upton, Long Island, New York, USA
H.L. Owen
UMAN, Manchester, United Kingdom
M. Shaevitz
Columbia University, New York, USA

DAEδALUS (Decay At rest Experiment for δ_cp At a Laboratory for Underground Science) has been proposed to measure the value of the CP violating phase delta through the oscillation of low energy muon anti-neutrinos to electron antineutrinos. With a single large detector, three accelerators at different distances enable the oscillation to be measured with sufficient accuracy. We have proposed the superconducting multi-megawatt DAEδALUS Supercinducting Ring Cyclotron (DSRC) as the means of producing the 800 MeV 12 mA protons required, through the acceleration of H₂⁺, ions with highly efficient stripping extraction. The DSRC comprises twin ion sources and injector cyclotrons, followed by a booster. The injector cyclotron can also be used for a separate experiment, IsoDAR (Isotope Decay At Rest) in which low energy protons produce Lithium 8, and thus a very pure electron antineutrino source which can be used to measure, or rule out, short range oscillation to a sterile neutrino. We describe recent developments in the designs of the injector and the booster, and the prospects for the two experiments.

MOPFI074

Ultracold and High Brightness Electron Source for Next Generation Particle Accelerators

laser, plasma, brightness, emittance

452

G.X. Xia, R. Appleby, W. Bertsche, M.A. Harvey
UMAN, Manchester, United Kingdom
S. Chattopadhyay
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
S. Chattopadhyay
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A.J. Murray
The University of Manchester, The Photon Science Institute, Manchester, United Kingdom

The ultra-cold plasma-based electron source has recently been proposed as an alternative to the conventional photoemitters or thermionic electron guns, which are widely used in today’s particle accelerators. The advantages of the ultra-cold plasma-based electron source lie in the fact that the electron beam extracted from the cold plasma (from ionization of cold atoms) has very low electron temperature, e.g. down to 10 K, and has the potential for producing high brightness and ultra-short electron bunches. All these features are crucial for the next generation particle accelerators, e.g. free electron lasers, plasma-based accelerators and the future linear colliders. In this paper, we will introduce our proposed facility on cold electron source based at Photon Science Institute (PSI) in the University of Manchester.

MOPFI078

The Possibility of Generation of High Energy Electron Beam at the SNS Facility

acceleration, laser, linac, solenoid

458

T.V. Gorlov, A.V. Aleksandrov, V.V. Danilov
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL/SNS is managed by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725
The linac of the SNS accelerator facility can be used to produce an electron beam with 300-400 MeV energy. At present there are a few predesigned experiments with electron beam that can be alternatively carried out at the SNS. However, the SNS linac is designed and optimized for acceleration of H⁻ , which brings some problems when considering direct acceleration of electrons. Alternative machine setup for electron acceleration and transport are discussed. Here, we present a study of the optimal electron beam parameters that can be achieved without any significant changes of the SNS accelerator.

MOPFI082

Redesign and Development of the Shanghai Electron Beam Ion Trap

ion, vacuum, alignment, cryogenics

467

D. Lu, Y. Shen, Z. Shi, J. Xiao, Y. Yang, Y. Zou
Fudan University, Shanghai, People's Republic of China

Over the last few years the Shanghai Electron Beam Ion Trap (EBIT) has been successfully redesigned and rebuilt. The original machine, developed under collaboration with the Shanghai Institute of Nuclear and Applied Physics, first generated an electron beam in 2005. Shanghai EBIT could be operated with electron beam energies between 1 and 130 keV and currents up to 160 mAmps. After several years of operation, it was found that some improvements/modifications to the old design were necessary. This contribution will discuss several of the main aspects of the redesigned Shanghai EBIT. So far it has been operated up to an electron energy of 40 keV with an current density of over 2400 A per square cm. The new EBIT is made primarily from Titanium instead of Stainless Steel and has an order of magnitude better background vacuum, a more efficient and economical cryogenic system, and also excellent optical alignment. Finally the magnetic field in the central drift tube region can reach up till 4.8 T.

MOPME003

Development of Diamond Sensors for Beam Halo and Compton Spectrum Diagnostics After The Interaction Point of ATF2

collimation, simulation, photon, vacuum

470

S. Liu, P. Bambade
LAL, Orsay, France
S. Bai
IHEP, Beijing, People's Republic of China
T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan

ATF2 is a low energy (1.3GeV) prototype of the final focus system for ILC and CLIC linear collider projects. A major issue at ATF2 and in linear colliders is to control the beam halo, which consists of tails extending far beyond the Gaussian core of the beam. At present there is no dedicated collimation for the beam halo at ATF2, and the transverse distribution near the interaction point is not well known. The development of a sensor based on CVD diamond to scan the beam halo in the vacuum chamber a few meters after the interaction point is presented. This system also aims to detect the Compton recoil electrons generated by the laser interferometer (Shintake monitor) used to measure the beam size at the interaction point of ATF2.

MOPME004

Fast Luminosity Monitoring using Diamond Sensors for Super Flavour Factories

luminosity, scattering, photon, positron

473

C. Rimbault, P. Bambade
LAL, Orsay, France

Super flavour factories aim to reach very high luminosities thanks to a new concept whereby the ultra-low emittance beams collide with a large crossing angle. Fast luminosity measurements are needed as input to luminosity optimization and feedback in the presence of dynamic imperfections. The required small relative precision can be reached exploiting the very large cross section of the radiative Bhabha process at zero photon scattering angle. The instrumental technique selected to sustain the large particle fluxes is based on diamond sensors to be positioned via moveable stages immediately outside the beam pipe, at locations chosen to minimize the contamination from other particle loss mechanisms.

MOPME005

Goubau Line and Beam Characterization of TURBO-ICT for SwissFEL

instrumentation, FEL, resonance, laser

476

S. Artinian, J.F. Bergoz, F. Stulle
BERGOZ Instrumentation, Saint Genis Pouilly, France
P. Pollet, V. Schlott
PSI, Villigen PSI, Switzerland

SwissFEL will be able to operate with electron bunch doublets 28ns apart. Each of the bunches carries 10pC to 200pC of charge with bunch lengths of a few femto-seconds. For charge calibration of the FEL photon pulses, a measurement accuracy of 1% is desired. The Turbo-ICT accomplishes these requirements with negligible beam position and bunch length dependence. It is insensitive to dark current and features high immunity to background noise. We characterize the Turbo-ICT performance on a Goubau line, also known as single-wire transmission line. The Goubau line utilizes electromagnetic fields with frequencies up to many GHz. It allows accurate bench testing including beam position and bunch length dependence. The results are compared to beam measurements performed at the SwissFEL Injector Test Facility (SITF).

MOPME006

The New Orbit Correction System at ELSA

polarization, closed-orbit, acceleration, extraction

479

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

ELSA is a fast ramping stretcher ring currently supplying polarized electrons with energies up to 2.4 GeV. To preserve the degree of polarization, the vertical orbit needs to be continuously corrected during beam acceleration. The acceleration is usually performed within 300 ms, with a maximum ramping speed of 6 GeV/s. We aim to achieve a vertical rms deviation not exceeding 50 μm all along the fast energy ramp. In the near future we plan to accelerate polarized electrons up to 3.2 GeV. Therefore, both the power supplies and the corrector magnets have been currently upgraded: first, new power supplies working with a pulsed transistor H-Bridge were developed and successfully installed. Additionally, the existing vertical corrector magnets will now be replaced by newly developed ones. In our contribution, we will present the new correction hardware supplemented by the beam position monitors and their readout electronics.

MOPME007

High Resolution Synchrotron Light Analysis at ELSA

synchrotron, diagnostics, vacuum, optics

482

S. Zander, F. Frommberger, P. Hänisch, W. Hillert, M.T. Switka
ELSA, Bonn, Germany

Funding: Funded by the DFG within the SFB/ TR 16
The Electron Stretcher Facility ELSA provides polarized electrons with energies up to 3.5 GeV for external hadron experiments. In order to suffice the need of stored beam intensities towards 200 mA, advanced beam instability studies need to be carried out. An external diagnostic beamline for synchrotron light analysis has been set up and provides the space for multiple diagnostic tools including a streak camera with time resolution of < 1 ps. Beam profile measurements are expected to identify instabilities and reveal their thresholds. The effect of adequate countermeasures is subject to analysis. The current status of the beamline development will be presented.

MOPME008

Beam Diagnostics by Using Bunch-by-bunch Feedback Systems at the DELTA Storage Ring

feedback, injection, kicker, laser

485

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

Funding: Work supported by BMBF (05K10PEB)
At DELTA, a 1.5-GeV electron storage ring operated by the TU Dortmund University, longitudinal and transverse bunch-by-bunch feedback systems are in use to detect and suppress multi-bunch instabilities. Besides that, the digital feedback systems are excellent diagnostics tools. As an example, by exciting a certain number of bunches within the bunch train, the coupling to the non-excited bunches can be investigated below and above the instability threshold. Other examples include studies of the injection process and monitoring bunch oscillations during sudden beam loss. First experimental results will be presented in this paper.

MOPME010

Transverse Beam Profile Diagnostics using Point Spread Function Dominated Imaging with Dedicated De-focusing

radiation, target, background, focusing

488

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

Transverse beam profile diagnostics in electron accelerators is usually based on direct imaging of a beam spot via optical radiation (transition or synchrotron radiation). In this case the fundamental resolution limit is determined by radiation diffraction in the optical system. A method to achieve resolutions beyond the diffraction limit is to perform point spread function (PSF) dominated imaging, i.e. the recorded image is dominated by the resolution function of a point source (single electron), and with knowledge of the PSF the true image (beam spot) may be reconstructed. To overcome the limited dynamical range of PSF dominated imaging, a dedicated de-focusing of the optical system can be introduced. In order to verify the applicability of this method, a proof-of-principle experiment has been performed at the Mainz Microtron MAMI (University of Mainz, Germany) using optical transition radiation. Status and results of this experiment will be presented.

MOPME011

Investigation of the Applicability of Parametric X-ray Radiation for Transverse Beam Profile Diagnostics

radiation, photon, diagnostics, background

491

G. Kube, C. Behrens
DESY, Hamburg, Germany
A.S. Gogolev, Yu.A. Popov, A. Potylitsyn
TPU, Tomsk, Russia
W. Lauth
IKP, Mainz, Germany
S. Weisse
DESY Zeuthen, Zeuthen, Germany

Transverse beam profile diagnostics in electron linacs is widely based on optical transition radiation (OTR) as standard technique which is observed in backward direction when a charged particle beam crosses the boundary between two media with different dielectric properties. The experience from modern linac based light sources like LCLS or FLASH shows that OTR diagnostics might fail because of coherence effects in the OTR emission process. A possibility to overcome this limitation is to measure at much shorter wavelengths, i.e. in the X-ray region, using parametric X-ray radiation (PXR) which additionally offers the advantage to be generated at crystal planes oriented under a certain angle to the crystal surface, thus allowing a spatial separation from a possible COTR background *. A first test experiment has been performed at the Mainz Microtron MAMI (University of Mainz, Germany) in order to study the applicability of PXR for beam diagnostics, and the status of this experiment will be presented.
* A. Gogolev, A. Potylitsyn, G. Kube, Journal of Physics 357 (2012) 012018

MOPME012

Single-bunch Longitudinal Phase Space Diagnostics in Multi-bunch Mode at the European XFEL

septum, simulation, dipole, diagnostics

494

M. Yan, C. Gerth
DESY, Hamburg, Germany

Dedicated longitudinal electron beam diagnostics is highly demanded for the control and optimization of modern X-ray free-electron lasers (XFEL). At the European XFEL, 3 transverse deflecting structures (TDS) will be installed at different locations of the accelerator for measurements of slice emittance and longitudinal profile. Operation of a TDS in combined use with an energy spectrometer, e.g. a dispersive section after a single dipole magnet, allows additionally for longitudinal phase space (LPS) measurements. However, utilization of a dipole magnet is not compatible with single-bunch measurements in multi-bunch operation mode, which will be the standard operation mode of the European XFEL. In this paper, we propose a LPS diagnostic beamline consisting of a TDS, fast kicker and septum magnet for the European XFEL. The layout of the accelerator lattice with optimized optics for LPS measurements will be presented.

MOPME014

Electro-optical Bunch Length Measurements at the ANKA Storage Ring

laser, wakefield, storage-ring, background

500

N. Hiller, A. Borysenko, E. Hertle, E. Huttel, V. Judin, B. Kehrer, S. Marsching, A.-S. Müller, M.J. Nasse, A. Plech, M. Schuh, S.N. Smale
KIT, Karlsruhe, Germany
P. Peier, V. Schlott
PSI, Villigen PSI, Switzerland
B. Steffen
DESY, Hamburg, Germany

Funding: Supported by the Initiative and Networking Fund of the Helmholtz Association under contract number VH-NG-320 and by the German Federal Ministry of Education and Research under contract number 05K10VKC
A setup for near-field electro-optical bunch length measurements has recently been installed into the UHV system of the ANKA storage ring. For electro-optical bunch length measurements during ANKA's low alpha operation, a laser pulse is used to probe the field induced birefringence in an electro-optical crystal (GaP in our case). The setup allows for both electro-optical sampling (EOS, multi-shot) and spectral decoding (EOSD, single- and multi-shot) measurements. This paper presents first results and discusses challenges of this method employed for the first time at a storage ring.

MOPME021

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

ion, injection, acceleration, vacuum

515

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

Ionization profile monitors (IPM) were installed in the 3-GeV RCS ring of J-PARC and used to observe the beam-profile for the transverse plane in beam commissioning. These electrodes and MCPs of IPMs were upgraded in 2012 summer shutdown in order to improve the external electric field for leading the electrons and ions to MCPs. This presentation will be described the results of observed beam profile in beam commissioning and be discussed the new issues for the ion and electron collection mode.

MOPME027

Bunch Length Measurement of 181 MeV Beam in J-PARC Linac

linac, target, vacuum, simulation

532

A. Miura, H. Oguri, N. Ouchi, J. Tamura
JAEA/J-PARC, Tokai-mura, Japan
A. Feschenko, A.N. Mirzojan
RAS/INR, Moscow, Russia
K. Futatsukawa, T. Miyao
KEK, Ibaraki, Japan
M. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan

In J-PARC Linac, an energy and intensity upgrade project has started since 2009 using Annular Coupled Structure (ACS) cavities. Because the longitudinal matching before ACS cavities is additionally required, we decided to employ the bunch shape monitors (BSMs) to measure the longitudinal beam profile. After three years from the start of BSM project, three BSMs were fabricated. All three BSMs were installed during the summer shutdown of 2012. We tried to measure the longitudinal beam profile exited from SDTL cavities. In this paper, we introduce the outline of BSM project, the first data acquisition and related small problems.

MOPME028

A Preliminary Study of the Vibration Wire Monitor for Beam Halo Diagnostic in J-PARC L3BT

diagnostics, proton, injection, linac

535

K. Okabe, M. Kinsho, K. Yamamoto, M. Yoshimoto
JAEA/J-PARC, Tokai-mura, Japan

In the J-PARC 3-GeV Rapid Cycle Synchrotron (RCS), transverse beam halo diagnostic and scraping are required to increase the output beam power. Wire scanners and halo scrapers were used for measurement of projected beam distributions to determine the extent of beam halo formation at Linac-3GeV Beam Transport line (L3BT). In order to determine more detail of halo formation, Vibration Wire Monitor (VWM) was installed in L3BT for the beam halo measurement and the offline study at the test stand with low energy electron gun are started. The high sensitivity of the VWM makes it a prospective one for investigation of beam halo and weak beam scanning. In this paper, we will report a preliminary results of offline studies and beam halo measurement by VWM at L3BT.

MOPME031

Emittance Measurement with Multi-wire Scanners for BEPC-II Linac

emittance, positron, linac, injection

541

H. Geng, W.B. Liu, W. Qiao, Q. Qin, Y.F. Sui, Y. Yue
IHEP, Beijing, People's Republic of China

During the BEPC-II linac upgrade, five wire scanners have been installed in the common transport line, which makes a fast emittance measurement possible. In this paper, we will show the primary results of BEPC-II linac emittance measurement using multi-wire scanner method. The least squares method will be used for data analysis. A comparison of the results with the ones obtained by quad scan method will also be given.

MOPME036

Prototype Experiment Preparation of a 54.167MHz Laser Wire System for FEL-THz Facility at CAEP

laser, photon, FEL, cathode

550

D. Wu
TUB, Beijing, People's Republic of China
W. Bai, M. Li, H. Wang, J. Wang, X. Yang
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

In this paper, a prototype experiment preparation of a 54.167 MHz laser wire system is presented, which will be used to measure the beam size of a CW DC gun built as an electron source of FEL-THz facility in China Academmy of Engineering Physics (CAEP). The rms beam size is less than 1 mm and the average current of the electron beam is more than 1 mA. This new-type LW system ultilizes the excess power other the photocathode drive laser and becomes much cheaper and simpler. Plus, it can distinguish beams with different energies which are very close in ERLs. The system layout and the simulation results are also presented.

MOPME038

A New Theoretical Design of BLM System for HLS II

vacuum, scattering, monitoring, emittance

553

Y.K. Chen, L.J. He, J. Li, W. Li, Y. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China

Beam loss monitoring (BLM) system has been commonly used to detect the vacuum leakage. The existing BLM system for Hefei Light Source (HLS) was built in 2000. It played an important role in analyzing beam loss distribution and regulating the machine operation parameters. Recently, HLS is being upgraded to HLS II. The emittance will be decreased to increase the brilliance of synchrotron radiation. The Touschek lifetime will be much shorter than before, and dominate the total beam lifetime. It is necessary to redesign the BLM system for HLS II. The most important part of this work is to find a better method of monitoring Touschek lifetime by BLM system while keeping its general functions. According to the results of our research, a preliminary theoretical design for the new BLM system is proposed in this paper. This new system will play an important role in the storage ring commissioning, troubleshooting, and beam lifetime studying.

MOPME039

A New Method of Acquiring Fast Beam Transversal Profile in the Storage Ring

synchrotron, factory, synchrotron-radiation, simulation

556

C. Cheng, P. Lu, B.G. Sun, K. Tang, F.F. Wu, Y.Y. Xiao, Y.L. Yang, Z.R. Zhou, J.Y. Zou
USTC/NSRL, Hefei, Anhui, People's Republic of China

A new method of acquiring fast beam transverse profile has been developed and will be used in HLS II. This method is based on four signals from MAPMT (multi-anode photo-multiplier tube) and logarithm processing technique. First, the calculation formula of beam transversal size and position are deduced using above method. Then, the main performances (e.g. sensitivity and linearity range) are analyzed. According to stimulation result, regardless of cross-talk and inconsistency between channels, the size signal has a linear relation with size s when s=0.8-2mm and position d=±2mm, the position signal has a linear relation with position d and the linear range exceeds ±2mm when s=0.8-2mm. With channel cross-talk and channel inconsistency being considered, the stimulation results also are given. Finally, a fast beam transverse profile monitor is designed and provides turn-by-turn measurement of the beam transverse profile.

MOPME049

Status of Non-destructive Bunch Length Measurement based on Coherent Cherenkov Radiation

radiation, target, diagnostics, vacuum

583

H.X. Deng, S.L. Lu, T. Yu, J.B. Zhang
SINAP, Shanghai, People's Republic of China
G.A. Naumenko, A. Potylitsyn, M.V. Shevelev, D.A. Shkitov
TPU, Tomsk, Russia

Funding: This work was supported by the joint Russian-Chinese grant (RFBR 110291177 and NSFC 11111120065) and partially by the Program of Russian MES “Nauka” and the Chinese NSFC 11175240.
As a novel non-destructive bunch length diagnostic of the electron beam, an experimental observation of the coherent Cherenkov radiation generated from a dielectric caesium iodide crystal with large spectral dispersion was proposed for the 30MeV femtosecond linear accelerator at Shanghai Institute of Applied Physics (SINAP). In this paper, the theoretical design, the experimental setup, the terahertz optics, the first angular distribution observations of the coherent Cherenkov radiation, and the future plans are presented.
* Shevelev M. et al., Journal of Physics: Conf. Ser. 357 (2012) 012023.

MOPME051

Development of Cavity Beam Position Monitor System

cavity, FEL, simulation, coupling

586

B.P. Wang, Y.B. Leng, Y.B. Yan, L.Y. Yu, R.X. Yuan, W.M. Zhou
SINAP, Shanghai, People's Republic of China

Shanghai soft X-ray free electron laser (SXFEL) facility requires beam position resolution better than 1 μm in the undulator sections. Cavity BPM system, feasible in obtaining sub micron position resolution, has been developed to achieve the goal. Two cavity prototypes with high Q and low Q were designed and fabricated. The relevant dedicated electronic, which could cover the two types of cavity BPMs, also have been developed. Fast fourier transform (FFT) and digital down converted based algorithms were implemented. The beam test of the whole system has been scheduled on the Shanghai deep ultraviolet (SDUV) FEL facility. The cavity design, electronic architecture, achieved performance during beam test will be presented.

MOPME058

DEVELOPMENT OF A CAVITY-TYPE BEAM POSITION MONITORS WITH HIGH RESOLUTION FOR ATF2

cavity, dipole, simulation, extraction

604

S.W. Jang, E.-S. Kim
KNU, Deagu, Republic of Korea
Y. Honda, T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan

We have developed a high resolution beam position monitors for ATF2 at KEK, which is an accelerator test facility for International Linear Collider(ILC). The main goals of ATF2 are achievement of 37nm beam size and 2nm beam position resolution for beam stabilization. For these goals, low-Q IP-BPM(Interaction Point Beam Position Monitor) with latency of 20 ns are being developed. In this paper, we will describe about design of Low-Q IP-BPM, the basics test results as RF test and BPM sensitivity test. Electronics for Low-Q IP-BPM will be also described.

MOPME060

Introduction to Beam Diagnostics Components for PAL-ITF

diagnostics, laser, gun, radiation

610

H. J. Choi, M.S. Chae, J.H. Hong, C. Kim, D.T. Kim, S.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea

Pohang Accelerator Laboratory (PAL) is building the 4th generation X-ray free electron laser (XFEL). The Injection Test Facility (ITF) is a test facility established to improve the functions of the laser gun and pre-injector to be installed in XFEL. To improve the effects of ITF, two factors are required. The first is to be able to generate low-emittance electron beams stably at the laser gun, and the second is to control increasing emittance by space charge effect by accelerating electron beams with high energy at the pre-injector. In this way, high-quality electron beams can be materialized. Various beam diagnostics are installed in the accelerator system for beam diagnostics and measurements. Five kinds of beam diagnostics were installed in the PAL-ITF. These are (1) ICT and (2) Faraday Cup to measure current and electrons charge, (3) Stripline BPM to measure the location of beams, (4) a YAG/OTR Screen Monitor to measure beam energy and transverse profile motion and (5) a Wire Scanner to measure beam size. In this paper, the purposes and properties of each diagnostic unit and measurement results are introduced.

MOPME061

Femtosecond e-bunch Length Measurement at fs-THz Accelerator at PAL

radiation, linac, laser, gun

613

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

Longitudinal distribution of femto-second electron beam has been evaluated by the coherent transition radiation Michelson interferometer with the reconstruction procedure from interferograms. We measure the bunch length of the Thz Accelerator using interferogram method in Pohang Accelerator Lab and compare with the energy of transition radiation and bunch length.

MOPME062

UV and X-ray Diffraction Radiation for Submicron Noninvasive Diagnostics

radiation, diagnostics, target, polarization

616

D.Yu. Sergeeva, M.N. Strikhanov, A.A. Tishchenko
MEPhI, Moscow, Russia

Funding: This work was partially supported by Russian Ministry of Education and Science (State contract 12.527.12.5002).
Diffraction radiation (DR) arises when a charged particle moves near a target. The theory of X-ray DR from single particles was created in [*, **], and recently the theory has been developed for bunches [***]. DR from relativistic particles is used for noninvasive bunch diagnostics and also for creating new and effective sources of radiation, including Free-electron laser based on the Smith-Purcell effect. In the present work we explore theoretically DR from the bunch of ultrarelativistic charged particles at X-ray and UV frequencies domains. It is shown that incoherent part of form-factor, describing the effect of N electrons in bunch, exists and differs from the unity. The coherent part of radiation depends on transversal size of the bunch as ratio of the Bessel function to its argument. The coherence effects are proved to be important up to the wavelengths much less than transversal size of the bunch. The results obtained open the possibility to diagnose bunches of the submicron size with very high accuracy.
* A.A. Tishchenko et al, PLA. 359 (2006) 509.
** A.P. Potylitsyn et al, Diffraction radiation from relativistic particles, Springer, 2010
*** D.Yu. Sergeeva et al, Proc. Channeling-2012, p.52, 2012

MOPME063

Backward X-ray Transition Radiation from Multilayered Target for Submicron Beam Diagnostics

radiation, target, diagnostics, polarization

619

A.A. Tishchenko, D.Yu. Sergeeva, M.N. Strikhanov
MEPhI, Moscow, Russia
K.O. Kruchinin
Royal Holloway, University of London, Surrey, United Kingdom

Funding: This work was partially supported by Russian Ministry of Education and Science (State contract 12.527.12.5002).
Backward transition radiation (TR) is a TR arising in the direction of mirror reflection relative to the charged particles trajectory. Therefore for oblique incidence it can be emitted under big angles which is useful from point of view of measuring of the radiation. In spite of the fact that backward TR in X-ray frequency domain is much weaker than forward TR [*], it has recently been proposed by A.P. Potylitsyn and others [**] as an instrument for submicron electron beam diagnostics. In this work we propose to use the multilayered target in order to enhance the resulting radiation, i.e. to use resonant backward X-ray TR. So far X-ray TR has not been explored theoretically for backward geometry. It is shown that the expressions obtained coincide in special case of forward resonant X-ray TR with the results by L. Durand (***) and X. Artru (****). We explore the spectral and angular characteristics of resonant backward X-ray TR form point of view of submicron beam diagnostics for the ultrarelativistic charged particles bunches. The role of absorption in the target material and also the coherent and incoherent parts of the radiation is analyzed
* A.A. Tishchenko et al, NIMB 227 (2005) 63.
** L.G. Sukhikh et al, J of Phys: Conf. Ser. 236 (2010) 012011.
*** L. Durand, Phys Rev D11 (1975) 89.
**** X. Artru et al, Phys Rev D12 (1975) 1289.

MOPME067

Non-Invasive Bunch Length Diagnostics Based on Interferometry From Double Diffraction Radiation Target

target, radiation, diagnostics, FEL

631

D.A. Shkitov, G.A. Naumenko, A. Potylitsyn, M.V. Shevelev
TPU, Tomsk, Russia
H.X. Deng, S.L. Lu, T. Yu, J.B. Zhang
SINAP, Shanghai, People's Republic of China

Funding: This work was supported by the joint Russian-Chinese grant (RFBR 110291177 and NSFC 11111120065) and partially by the Program of Russian MES “Nauka” and the SINAP Xinrui Program Y15501A061.
Reliable and precise non-invasive beam diagnostics technique to measure length of sub-picosecond electron bunches are required for new accelerator facilities (FEL, et al.). Investigations of coherent radiation generated by such bunches using different interferometers allow to determine a bunch length*. Measuring a dependence of radiation yield intensity from two DR targets on a distance between them (the intrinsic DR interferogram), it is possible to obtain the same information. Such a non-invasive technique can be directly used for ultra-short bunch length measurements. Recently the first experiment with a double DR target was carried out at the SINAP fs linac facility** with parameters described in***. The double DR target was consisted of two plates made from Al foil. The pyro-electric detector SPI-D-62 was used. Here we report the results of the second stage of our investigations. The DR interferograms of different electron bunch length were measured. The bunch length was reconstructed using the heuristic model based on the dimension theory and simulation data. We compare the results from DR interferograms and Michelson interferometer measurements and show their similarity.
*Murokh A. et al., NIMA 410 (1998) 452.
**Zhang J.B., Shkitov D.A. et al., IBIC’12 MOPB65 (2012).
***Lin X., Zhang J. et al., Chin. Phys. Let. V. 27 N. 4 (2010) 044101.

MOPME068

Feasibility Study of a 2nd Generation Smith-Purcell Radiation Monitor for the ESTB at SLAC

radiation, simulation, background, vacuum

634

N. Fuster Martinez, A. Faus-Golfe, J. Resta-López
IFIC, Valencia, Spain
H.L. Andrews
LANL, Los Alamos, New Mexico, USA
F. Bakkali Taheri, R. Bartolini, G. Doucas, I.V. Konoplev, C. Perry, A. Reichold, S.R. Stevenson
JAI, Oxford, United Kingdom
J. Barros, N. Delerue, M. Grosjean
LAL, Orsay, France
V. Bharadwaj, C.I. Clarke
SLAC, Menlo Park, California, USA

The use of a radiative process such as the Coherent Smith-Purcell Radiation (CSPR) is a very promising non-invasive technique for the reconstruction of the time profile of relativistic electron bunches. Currently existing CSPR monitors do not have yet single-shot capability. Here we study the feasibility of using a CSPR based monitor for bunch length measurement at the End Station Test Beam (ESTB) at SLAC. The aim is to design a second-generation device with single-shot capability, and use it as a diagnostic tool at ESTB. Simulations of the spectral CSPR energy distribution and feasibility study have been performed for the optimization of the parameters and design of such a device.

MOPME072

Performance Tests of a Short Faraday Cup Designed for HIE-ISOLDE

ion, diagnostics, cryomodule, cryogenics

646

E.D. Cantero, W. Andreazza, E. Bravin, M.A. Fraser, D. Lanaia, A.G. Sosa, D. Voulot
CERN, Geneva, Switzerland

Funding: E.D.C, D.L. and A.S. acknowledge CATHI Marie Curie ITN: EU-FP7-PEOPLE-2010-ITN Project number 264330. M.A.F acknowledges co-funding by the European Commission (Grant agreement PCOFUND-GA-2010-267194)
The On-Line Isotope Mass Separator (ISOLDE) facility at CERN is being upgraded in order to deliver higher energy and intensity radioactive beams. The final setup will consist in replacing the energy variable part of the normal conducting REX post-accelerator with superconducting cavities. In order to preserve the beam emittance, the drift space between the cryomodules housing these cavities has been kept to a minimum. As a consequence, the longitudinal space available for beam diagnostics is severely limited in the inter-cryomodule regions. A Faraday cup (FC) will be installed to measure beam currents, and due to the tight spatial constraints, its length is much smaller than usual. This poses a great challenge when trying to avoid the escape of ion-induced secondary electrons, which would falsify the current measurement. Two prototypes of such a short FC have therefore been tested at REX-ISOLDE using several beam intensities and energies, with the aim of determining its accuracy. In this paper the experimental results obtained for the two prototype cups are presented together with numerical calculations of the electrostatic fields that are produced inside the cup.

MOPME075

Laser Based Stripping System for Measurement of the Transverse Emittance of H⁻ Beams at the CERN LINAC4

laser, linac, background, emittance

652

T. Hofmann, E. Bravin, U. Raich, F. Roncarolo
CERN, Geneva, Switzerland
B. Cheymol
ESS, Lund, Sweden

Funding: LA3NET is funded by the European Commission under Grant Agreement Number GA-ITN-2011-289191
The new LINAC4 at CERN will accelerate H⁻ particles to 160 MeV and allow high brightness proton beam transfers to the Proton Synchrotron Booster, via a charge-exchange injection scheme. This paper describes the conceptual design of a laser system proposed for transverse profile and emittance measurements based on photon detachment of electrons from the H⁻ ions. The binding energy of the outer electron is only 0.75 eV and can easily be stripped with a laser beam. Measuring the electron signal as function of the laser position allows the transverse beam profile to be reconstructed. A downstream dipole can also be used to separate the laser neutralized H⁰ atoms from the main H⁻ beam. By imaging these H⁰ atoms as a function of laser position the transverse emittance can be reconstructed in the same way as in traditional slit-and-grid systems. By properly dimensioning the laser power and spot size, this method results in negligible beam losses and is therefore non-destructive. In addition, the absence of material intercepting the H⁻ beam allows the measurement of a full power H⁻ beam. This paper will focus on the general design and integration of both the laser and H⁰ detector systems.

MOPME077

Electro-0ptical Bunch Profile Measurement at CTF3

laser, photon, vacuum, polarization

658

R. Pan, A. Andersson, W. Farabolini, A. Goldblatt, T. Lefèvre, M. Martyanov, S. Mazzoni, S.F. Rey, L. Timeo
CERN, Geneva, Switzerland
W.A. Gillespie, R. Pan, D.A. Walsh
University of Dundee, Nethergate, Dundee, Scotland, United Kingdom
S.P. Jamison
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

A new electro-optic bunch profile monitor has recently been installed in CLIC Test Facility 3 at CERN. The monitor is based on an electro-optic spectral decoding scheme which reconstructs the longitudinal profile of the electron bunch by measuring its Coulomb field. The system uses a 780 nm fibre laser system, transported over a 20m long distance to the interaction chamber, where a ZnTe crystal is positioned close to the beam. The assembly also contains a traditional OTR screen, which is coupled to a second optical line and used to adjust the temporal overlap between the laser and the electron pulse. This paper presents the detection system in detail, as well as reporting on the first measurements performed with beam.

MOPWA018

CW-type HV Power Supply of 50 Hz and its Application in Accelerator Power Supply

high-voltage, power-supply, impedance, damping

699

Z.-F. He, D.M. Li, Y.H. Liu, S.L. Wang, J.-L. Zhang, Y.-T. Zhang
SINAP, Shanghai, People's Republic of China

Funding: The Knowledge Innovation Program of Chinese Academy of Sciences
　　The high-voltage power supply is an integral part of accelerator technology, as its stable and reliable output is an important guarantee for accelerator properly working. In a number of engineering practice of accelerator design and construction, we tried to use the Cockcroft-Walton (CW) type of power supply driven by 50 Hz and got success. It is of simple structure, low cost, easy maintenance, and high efficiency. This report describes the technical difficulties and the solutions in the CW-type power supply driven by 50 Hz. It also gives an introduction of the latest design of 800 kV/30 mA electron accelerator, which is being assembled at SINAP. Recent work has shown that it is an option to choose 50 Hz driven power system when it is more lenient on the voltage ripple but needed to be as high as possible on the energy conversion efficiency.

MOPWA021

Design of the Air Cooling System for the High Voltage Power Supply of a Electron Accelerator

power-supply, high-voltage, simulation, radiation

705

F. Zhong, X. Lei, J. Yang, L. Yang
HUST, Wuhan, People's Republic of China

High voltage electron accelerators are widely applied in many fields of radiation pro-cessing,and the high voltage power supply is the critical equipment for the accelerator. for the requirement of high voltage, the design of locate the power supply in a steel barrel filled with SF6 is commonly used. Considering the various losses of the power supply, an air-cooling system is needed. This paper presents the design of the air-cooling system for the high voltage power supply. The fluid simulation of SF6 based on Fluent and the optimal design of the air duct's structure and the thermal efficiency have been done. The comparison and analysis of the simulation and the empirical formula result is also carried out. It illustrates the design of the air-cooling system can satisfy the demand of the heat radiation This paper also provides an effective method for the optimal design of the air duct's structure and the maximize efficiency of heat exchange.

MOPWA030

Upgrade of the LHC Injection Kicker Magnets

vacuum, kicker, injection, impedance

729

M.J. Barnes, P. Adraktas, V. Baglin, G. Bregliozzi, S. Calatroni, F. Caspers, H.A. Day, L. Ducimetière, M. Garlaschè, V. Gomes Namora, J.M. Jimenez, N. Magnin, V. Mertens, E. Métral, B. Salvant, M. Taborelli, J.A. Uythoven, W.J.M. Weterings
CERN, Geneva, Switzerland

The two LHC injection kicker systems, comprising 4 magnets per ring, produce a kick of 1.3 T.m with a rise-time of less than 900 ns and a flattop ripple of less than ±0.5%. A beam screen is placed in the aperture of each magnet, to provide a path for the image current of the high intensity LHC beam and screen the ferrite yoke against wake fields. The screen consists of a ceramic tube with conductors in the inner wall. The initially implemented beam screen ensured a low rate of electrical breakdowns while providing an adequate beam coupling impedance. Operation with increasingly higher intensity beams, stable for many hours at a time, now results in substantial heating of the ferrite yoke, sometimes requiring cool down over several hours before the LHC can be refilled. During the long shutdown in 2013/2014 all 8 kicker magnets will be upgraded with an improved beam screen and an increased emissivity of the vacuum tank. In addition equipment adjacent to the injection kickers and various vacuum components will also be modified to help reduce the vacuum pressure in the kickers during high-intensity operation. This paper discusses the upgrades as well as their preparation and planning.

MOPWA034

Electron Tracking Simulations in the Presence of the Beam and External Fields

emittance, simulation, proton, space-charge

741

M. Patecki, B. Dehning, G. Iadarola, M. Sapinski
CERN, Geneva, Switzerland

The ionisation profile monitors installed in the CERN LHC and SPS, makes use of the ionisation of small quantities of injected neon gas by the circulating beam. The electrons produced are guided towards the readout system using a combination of electric and magnetic fields. However, in the presence of the beam field their tracks are modified and the resulting profile is distorted. The Geant4 physics simulation package has been used to simulate the ionisation process, while the CERN-developed PyECLOUD code has been used for tracking the resulting ionised particles. In this paper the results of simulations are compared with observations, with conclusions presented on the accuracy of the reconstruction of high-intensity beam profiles.

MOPWA036

GEM Detectors for the Transverse Profile Measurement of Low Energy Antiprotons and High Energy Hadrons

antiproton, hadron, cathode, scattering

747

J. Spanggaard, P. Carriere, S.C. Duarte Pinto, G. Tranquille
CERN, Geneva, Switzerland

Gas Electron Multipliers (GEM) are finding more and more applications in beam instrumentation. Gas Electron Multiplication is a very similar physical phenomenon to that which occurs in Multi Wire Proportional Chambers (MWPC), but for small profile monitors GEMs are much more cost effective to produce and maintain. In 2012, all Multi-Wire Proportional Chambers in the experimental areas of the Antiproton Decelerator at CERN were successfully replaced by Gas Electron Multipliers. This paper describes the choice of detector and reports on the commissioning of 20 GEM detectors for transverse profile measurement on low energy antiproton beams (5.3 MeV, equal to 100 MeV/c). It will also cover the development of, and first results from, a new 200x200 mm GEM detector for profiling the high energy muon beam (172 GeV/c) delivered to the COMPASS experiment and discuss the outlook for replacing all Multi-Wire Proportional Chambers in the CERN experimental areas by GEM based monitors.

MOPWA038

Flashbox Compact Beam Spectrometer and its Application to the High-gradient Acceleration Study

ion, dipole, acceleration, accelerating-gradient

753

A. Dubrovskiy, F. Tecker
CERN, Geneva, Switzerland
M. Jacewicz, R.J.M.Y. Ruber, V.G. Ziemann
Uppsala University, Uppsala, Sweden

A Flashbox compact spectrometer has been developed for the Two-beam Test Stand (TBTS), which is a part of the CLIC test facility CTF3 at CERN. It is used to study limitations of high-gradient acceleration in X-band structures being prototyped in the TBTS. The Flashbox is built around the beam tube such that an electron beam can pass to be accelerated in the X-band structure while charged particles emitted from the accelerating structure can be intercepted on the spectrometer consisting of detector plates aligned along the beam axis in combination with magnetic and electric fields. The Flashbox has made it possible to identify electrons and ions emitted by the accelerating structure during RF breakdown. We describe the Flashbox and first results.

MOPWA050

Bunch Train Characterisation for an Infra-red FEL Driven by an Energy Recovery Linac

FEL, pick-up, EPICS, diagnostics

786

T.T. Thakker, D. Angal-Kalinin, D.J. Dunning, F. Jackson, S.P. Jamison, J.K. Jones, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The IR-FEL on the ALICE test facility in the UK first achieved lasing in October 2010 and has since been characterised in terms of its output *. In this work we make a characterisation of electron bunch properties along a complete 100us macropulse to characterise the lasing-induced energy change and its effect on energy recovery. Measurements of bunch energy and timing are correlated with the FEL radiation output and discussed.
* N. R. Thompson et al, ‘First lasing of the ALICE infra-red Free-Electron Laser’, Nuclear Instruments and Methods A, 680 (2012) 117–123

MOPWA051

ZEMAX Simulations for an Optical System for a Diffraction Radiation Monitor at CesrTA

target, radiation, simulation, damping

789

T. Aumeyr, V. Karataev
JAI, Egham, Surrey, United Kingdom
M.G. Billing
CLASSE, Ithaca, New York, USA
L.M. Bobb, B. Bolzon, T. Lefèvre, S. Mazzoni
CERN, Geneva, Switzerland

Diffraction Radiation (DR) is produced when a relativistic charged particle moves in the vicinity of a medium. The target atoms are polarized by the electric field of the charged particle, which then oscillate thus emitting radiation with a very broad spectrum. The spatial-spectral properties of DR are sensitive to various electron beam parameters. Since the energy loss due to DR is so small that the electron beam parameters are unchanged, DR can be used to develop non-invasive diagnostic tools. The aim of this project is to measure the transverse (vertical) beam size using incoherent DR. To achieve the micron-scale resolution required by CLIC, DR in the UV and X-ray spectral-range must be studied. During the next few years, experimental validation of such a scheme will be conducted on the CesrTA at Cornell University, USA. This paper reports on simulations carried out with ZEMAX, studying the optical system used to image the emitted radiation.

MOPWA053

Sub-Micrometre Resolution Laserwire Transverse Beam Size Measurement System

laser, alignment, photon, background

795

L.J. Nevay, G.A. Blair, S.T. Boogert, V. Karataev, K.O. Kruchinin
Royal Holloway, University of London, Surrey, United Kingdom
A.S. Aryshev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
L. Corner, R. Walczak
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

Funding: The research leading to these results has received funding from the European Commission under the FP7 Research Infrastructures project Eu-CARD, grant agreement no. 227579
We present the results from the laserwire system at the Accelerator Test Facility 2 (ATF2) during recent operation after relocation to the virtual image point of the ATF2 final focus. The characterisation of the 150 mJ, 77 ps long laser pulses at a scaled virtual interaction point is used to deconvolve the transverse laserwire profile demonstrating a 1.16 ± 0.06 um vertical electron beam profile. Horizontal laserwire scans were used in combination with the vertical scans to measure the electron beam size using a full overlap integral model due to the problems presented by a large aspect ratio electron beam.

MOPWA056

Spectra of Coherent Smith-Purcell Radiation Observed from Short Electron Bunches: Numerical and Experimental Studies

radiation, diagnostics, simulation, target

801

F. Bakkali Taheri, G. Doucas, I.V. Konoplev, A. Reichold
JAI, Oxford, United Kingdom
H.L. Andrews
LANL, Los Alamos, New Mexico, USA
R. Bartolini
Diamond, Oxfordshire, United Kingdom
V. Bharadwaj, C.I. Clarke
SLAC, Menlo Park, California, USA
N. Delerue
LAL, Orsay, France
N. Fuster Martinez
IFIC, Valencia, Spain
J.D.A. Smith
TXUK, Warrington, United Kingdom
P. Stoltz
Tech-X, Boulder, Colorado, USA

Funding: This work performed [in part] under DOE Contract DE-AC02-7600515
There is a significant interest in the development of compact particle accelerators within research areas including X-ray and THz (T-ray) sources of radiation, particle physics and medical sciences. To support the progress in these areas, non-invasive, electron beam diagnostics that are capable of measuring a single femtosecond electron bunch are required. At the current stage such beam diagnostics for femtosecond-long electron bunches are still not available. The goal of the work presented is to understand the spectral characteristics of coherent Smith-Purcell radiation to enable its quick and reliable interpretation including the longitudinal profile reconstruction of electron bunches. The research presented comprises results from numerical modelling and experimental studies. Using the numerical data, we discuss the radiated spectra dependence on the electron bunch profile and analyse the results. We also discuss the experimental data and compare it with theoretical predictions.

MOPWA060

DITANET - An International Network in Beam Diagnostics

diagnostics, photon, instrumentation, synchrotron

813

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

Funding: Work supported by the EU under contract 215080.
Beam diagnostics systems are essential constituents of any particle accelerator; they reveal the properties of a beam and how it behaves in a machine. Without an appropriate set of diagnostic elements, it would simply be impossible to operate any accelerator complex, let alone optimize its performance. Beam diagnostics is also a rich field in which a great variety of physical effects are made use of and consequently provides a wide interdisciplinary base for the training of researchers. The DITANET Consortium develops beyond state-of-the-art beam diagnostic techniques for hadron and electron accelerators and trained more than 20 researchers between 2008 and 2012. This contribution summarizes the network's research outcomes in beam instrumentation and diagnostics.

MOPWA063

Proposed Coherent Diffraction Radiation Measurements of Bunch Length at ASTA

radiation, cryomodule, gun, laser

822

A.H. Lumpkin, J. Ruan, R.M. Thurman-Keup
Fermilab, Batavia, USA

Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The feasibility of using the autocorrelation of coherent diffraction radiation (CDR) as a non-intercepting diagnostics technique for bunch length and indirectly rf phase measurements is evaluated and proposed for the Advanced Superconducting Test Accelerator (ASTA) facility under construction at Fermilab. Previous experiments on an rf thermionic cathode gun beam at 50 MeV provide a proof-of-principle reference for the ASTA injector. The ASTA injector is based on an L-band rf photocathode (PC) gun with UV pulse drive laser, two L-band superconducting accelerator structures, a chicane bunch compressor, and an electron spectrometer. The injector energy of 40-50 MeV is expected. The 3-MHz micropulse repetition rate with micropulse charges up to to 3.2 nC and 1-ps bunch lengths should generate sufficient CDR signal for standard pyroelectric detectors to be used. The CDR signals will also be evaluated as a bunch compression signal for beam-based feedback for rf phase. The technique would also be applicable at high energy in straight transport lines after the cryomodules.

MOPWA064

Microwave Resonator Diagnostics of Electron Cloud Density Profile in High Intensity Proton Beam

cavity, proton, vacuum, simulation

825

Y.-M. Shin, J. Ruan, C.-Y. Tan, J.C.T. Thangaraj, R.M. Zwaska
Fermilab, Batavia, USA

We have developed an novel technique to accurately estimate the density of dilute electron clouds emitted from high intensity proton beams. The strong phase shift enhancement from multiple reflections of standing microwaves in a resonating beam pipe cavity has been demonstrated with numerical modeling using dielectric approximation and e S-parameter measurements. The equivalent dielectric simulation showed a ~ 10 times phase shift enhancement (Pi-mode, 1.516 GHz) with the cavity beam pipe compared to the waveguide model. The position-dependence of the technique is investigated by overlapping the field distributions of harmonic resonances. The simulation with various positions of dielectric insertions confirmed that resonance peaks in phase-shift spectra corresponding to the relative distance between field-nodes and electron cloud position, which allows for one-dimensional mapping. Preliminary experimental studies based on a bench-top setup confirm the results of the simulation showing that thicker reflectors enhance the phase-shift measurement of the electron cloud density.

MOPWA069

Time-resolved Electron Beam Position Monitor Macropulse Waveform Measurement in MkV Linear Accelerator at University of Hawaii Free Electron Laser Laboratory

FEL, controls, free-electron-laser, laser

837

P. Niknejadi, M.R. Hadmack, B.T. Jacobson, J. Madey, G.S. Varner
University of Hawaii, Honolulu, HI, USA

Real time waveform measurements of electron beams will provide valuable data and possibility of online bunch diagnostics in linear accelerators. The University of Hawaii Linear Accelerator utilizes a thermionic LaB6 cathode microwave gun injector and a single section of S-band linear accelerator capable of producing a 40MeV, 1-2 ps bunched electron beam with average current of 200mA over the duration of a 4.5 us macropulse. This beam, pulsed at 4 Hz, produces strong RF signal at 2.856 GHz which is coupled out of the beam-pipe by a family of stripline beam position monitors (BPM's) and read out using custom built logarithmic-difference based electronics installed in 2012.* A high speed Analog to Digital Convertor and Field-Programmable Gate Array will be used to digitize the signal and record the waveform. The goal is to make a cost effective oscilloscope on a chip/board with feasible and functional operation to achieve optimal beam configuration. The circuit board design, in-circuit programming, waveform digitization challenges, and preliminary results from the prototype will be presented at the conference.
* B. T. Jacobson, M. R. Hadmack, J. M. J. Madey, P. Niknejadi "Modular Logarithmic Amplifier Beam Position Monitor Readout System at University of Hawai’i," IBIC Conf. Proc. (2012)

MOPWA071

A Comparison of Electron Cloud Density Measurements at CesrTA

simulation, positron, resonance, pick-up

843

J.P. Sikora, J.A. Crittenden, D.O. Duggins, Y. Li, X. Liu
CLASSE, Ithaca, New York, USA
S. De Santis
LBNL, Berkeley, California, USA

Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
Several techniques have been employed to measure the electron cloud (EC) density in accelerators. These include Time Resolved Retarding Field Analyzers (TR-RFA) and Shielded Pickups (SPU) that measure the flux of cloud electrons onto the beam-pipe wall, as well as TE wave resonance techniques that measure the EC density in a region within the volume of the beam-pipe. We have made measurements to test the EC mitigation properties of different surface coatings and geometries, often with more than one technique used in the same test chamber. We present a comparison of bare aluminum chambers with those having a TiN coating, as well as the effect of beam conditioning. In addition, we will compare the results of the different measurement techniques used in the same chamber. These measurements were made at the Cornell Electron Storage Ring (CESR) which has been reconfigured as a test accelerator (CesrTA) having positron or electron beam energies ranging from 2 GeV to 5 GeV.

MOPWA072

MODELING FOR TIME-RESOLVED RETARDING FIELD ANALYZER MEASUREMENTS OF ELECTRON CLOUD BUILDUP AT CesrTA

vacuum, positron, dipole, pick-up

846

J.A. Crittenden, Y. Li, X. Liu, M.A. Palmer, J.P. Sikora
CLASSE, Ithaca, New York, USA

Funding: 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 mitigation techniques using custom vacuum chambers. Multibunch electron and positron beams of energies between 2.1 and 5.3 GeV with bunch spacings from 4 to 98 ns and bunch populations ranging from 10¹⁰ to 16·10¹⁰ provide highly differentiated sensitivity to the processes contributing to cloud buildup such as photoelectron production, cloud space-charge dynamics, and secondary electron emission. Measurements of the time dependence of cloud buildup using BPM-style shielded pickups have been shown to provide tight constraints on cloud buildup models. Recently, time-resolving retarding-field analyzers have been designed, installed and commissioned. These novel detectors combine the time-resolving feature of the shielded pickups with the fine transverse segmentation and cloud electron energy sensitivity of the time-integrating retarding-field analyzers used previously. We report on progress in modeling these measurements and quantify their sensitivity to various parameters describing the underlying physical processes contributing to cloud buildup.

MOPWA073

A Turn-by-turn Beam Profile Monitor using Visible Synchrotron Radiation at CESR-TA

synchrotron, synchrotron-radiation, radiation, emittance

849

S. Wang, D. L. Rubin, C.R. Strohman
CLASSE, Ithaca, New York, USA
R.F. Campbell, R. Holtzapple
CalPoly, San Luis Obispo, California, USA

Funding: Work supported by the National Science Foundation and Department of Energy under contract numbers PHY-0734867, PHY-1002467, DMR-0936384, and DE-FC02-08ER41538, DE-SC0006505
A fast beam profile monitor using visible synchrotron radiation (SR) has been constructed and installed in Cornell Electron Storage Ring. This monitor utilizes fast readout electronics based on the Hamamatsu H7260K multi-anode photomultiplier, which has a 32-channel linear array with 1mm channel pitch and sub-nanosecond rise time. In a low emittance lattice at 2 GeV, a double-slit interferometer is employed to measure the horizontal beam size. After careful calibration of the interference pattern, the horizontal beam size within a range of 100 to 500 microns can be measured with a precision of ±5 microns. Due to finite array size, the small vertical beam size is measured by imaging the pi-polarized component of the SR. The fast beam profile monitor is capable of measuring bunch-by-bunch turn-by-turn transverse beam sizes, which eliminates beam jitter inherent when imaging the average beam size with a CCD camera. Details of hardware and software controls are also discussed.

MOPWA078

The Calibration of the PEPPo Polarimeter for Electrons and Positrons

positron, photon, target, polarization

861

A.H. Adeyemi
JLAB, Newport News, Virginia, USA
E. J-M. Voutier
LPSC, Grenoble, France

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
The PEPPo (Polarized Electrons for Polarized Positrons) experiment at Jefferson Laboratory investigated the polarization transfer from longitudinally polarized electrons to longitudinally polarized positrons, with the aim of developing this technology for a low energy (~MeV) polarized positron source. Polarization of the positrons was measured by means of a Compton transmission polarimeter where incoming positrons transfer their polarization into circularly polarized photons that were subsequently analyzed by a thick polarized iron target. The measurement of the transmitted photon flux with respect to the orientation of the target polarization (±) or the helicity (±) of the incoming leptons provided the measurement of their polarization. Similar measurements with a known electron beam were also performed for calibration purposes. This presentation will describe the apparatus and calibrations performed at the injector at the Jefferson Laboratory to measure positron polarization in the momentum range 3.2-6.2 MeV/c, specifically to quantify the positron analyzing power from electron experimental data measured over a comparable momentum range.
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

MOPWA079

Characterization of the Analyzing Target of the PEPPo Experiment

target, polarization, positron, photon

864

O. Dadoun
LAL, Orsay, France
E. Froidefond, E. J-M. Voutier
LPSC, Grenoble, France

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177
Various methods have been investigated over the past decades for the production of polarized positrons. The purpose of the PEPPo (Polarized Electrons for Polarized Positrons) experiment is to demonstrate, for the first time, the production of polarized positrons from a polarized electron beam. This two-step process involves the production of circularly polarized photons in a high Z target via the bremsstrahlung process followed, within the same target, by the conversion of polarized photons into polarized e⁺e⁻ pairs through the pair creation process. The PEPPo experiment was performed in Spring 2012 at the injector of the Jefferson Laboratory using a highly spin-polarized (~85%) 8.3 MeV/c electron beam. The positron polarization was measured by means of a Compton transmission polarimeter over the momentum range from 3.2 MeV/c to 6.2 MeV/c. This presentation will discuss the experimental set-up with a special emphasis on the analyzing magnet constituting the polarization filter of the experiment. The knowledge of the analyzing target polarization will be discussed on the basis of simulations and calibrated to experimental data
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

MOPWA080

Design of a Fast, XFEL-quality Wire Scanner

photon, radiation, vacuum, instrumentation

867

M.A. Harrison, R.B. Agustsson, P.S. Chang, T.J. Hodgetts, A.Y. Murokh, M. Ruelas
RadiaBeam, Santa Monica, USA

RadiaBeam Technologies, in collaboration with the Pohang Accelerator Laboratory, has designed and built a fast wire scanner for transverse beam size measurements in the XFEL Injector Test Facility. The wire scanner utilizes three 25-micron diameter tungsten wires mounted vertically, horizontally, and diagonally on a single alumina card to measure the transverse beam size down to 10 microns with sub-micron accuracy of a 139-MeV electron beam. A double-ended design using dual bellows for actuation is used to reduce the vibrations of the wire holder during motion and negate the effects of air pressure on positioning. The servomotor-driven system is capable of performing full horizontal, vertical, and 45-degree scans in under a minute. Algorithms are presented for removing the broadening effect of the wires' thickness from the scanning data to measure beams that are as small or smaller than the wires. Furthermore, we present formulas for determining the beam's transverse spatial sizes (horizontal and vertical spot size and correlation) from the scan data.

MOPWO003

Multibunch Tracking Code Development to Account for Passive Landau Cavities

cavity, damping, impedance, radiation

885

M. Klein, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France

The MAX IV 3 GeV storage ring will achieve an ultra-low horizontal emittance of 0.24 nm rad by using a multibend achromat lattice. Passive harmonic cavities are introduced to relax the Touschek-lifetime and intrabeam scattering issues as well as fight collective beam instabilities via Landau damping. Since instabilities occur during injection, when the passive harmonic cavity potential is also time varying, it became important to simulate this transient process. The most promising approach was considered to be multibunch tracking which also allows for an arbitrary filling pattern. Since every bunch is represented by numerous macroparticles, internal motions as well as microstructures in the charge distribution can be followed.

MOPWO004

Simulations and Studies of Electron Beam Dynamics under Compton Back-scattering for the Compact X-ray Source ThomX

simulation, wakefield, collective-effects, photon

888

I.V. Drebot, C. Bruni, N. Delerue, T. Demma, A. Variola, Z.F. Zomer
LAL, Orsay, France
A. Loulergue
SOLEIL, Gif-sur-Yvette, France

Funding: This work is supported by the French "Agence Nationale de la Recherche" under reference ANR-10-EQPX-51, and also by grants from Région Ile-de-France, Université Paris-Sud and IN2P3/CNRS.
In this article are presented beam dynamics investiga- tions of a relativistic electron bunch in the compact storage ring ThomX (50 MeV), which is under construction at LAL to produce hard X-ray using Compton Back-Scattering (CBS). The effect of CBS has been implemented in a 6D tracking code. In addition to CBS, the influence of lattice non linearities and various collective effects on the flux of scattered Compton photons is investigated.

MOPWO009

Numerical Studies on the Impact of Ionized Residual Gas on an Electron Beam in an ERL

ion, emittance, simulation, linac

903

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

Funding: Supported by BMBF under contract number 05K10HRC
Energy Recovery Linacs (ERLs) are the most promising candidates for next-generation light sources now under active development. An optimal performance of these machines requires the preservation of the high beam brightness generated in the injector. For this, the impact of the ionized residual gas on the beam has to be avoided as it causes instabilities and emittance growth. Typical measures to reduce the effect of ion clouds are clearing electrodes and clearing gaps in the bunch train. In this paper, we present numerical studies of the impact of ion clouds on the electron bunch train. The simulations are performed with the software package MOEVE PIC Tracking developed at Rostock University. ’The model for the bunch and the ion cloud takes into account a distribution of macro particles. The interaction of the bunch with the ion cloud is computed with a 3D space charge model. Hence, particle tracking allows for detailed studies of bunch characteristics such as the emittance. The presented numerical investigations take into account the parameters of the ERL BERLinPro with the objective to deduce appropriate measures for the design and operation of BERLinPro.

MOPWO014

Numerical Methods to the Space Charge Compensation (SCC) Effect of the LEBT Beam

ion, space-charge, simulation, ion-source

915

S.X. Peng, J. Chen, J.E. Chen, Z.Y. Guo, P.N. Lu, Y.T. Luo, H.T. Ren, Z.H. Wang, Y. Xu, T. Zhang, J. Zhao
PKU, Beijing, People's Republic of China
A.L. Zhang
Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China

Numerical simulation as well as experimental researches on space charge compensation for high intensity, low energy ion beam has been done at Peking University (PKU). In this paper we will describe the simulation model proposed at PKU and use it on the PKU ECR single-charged ion source. It consists of a new concept of equivalent density and more consideration of physical process. A series of arithmetical equations is gained through theoretical derivation. Although no numerical solutions have been carried out from our computation, it is foreseeable that the final result will be achieved soon.

MOPWO036

Civil Engineering Feasibility Studies for Future Ring Colliders at CERN

linac, civil-engineering, collider, hadron

969

J.A. Osborne, O.S. Brüning, M. Klein, S. Myers, S. Myers, L. Rossi, C.S. Waaijer, F. Zimmermann
CERN, Geneva, Switzerland
M. Klein
DESY Zeuthen, Zeuthen, Germany

CERN civil engineers are studying the feasibility of future ring colliders to complement the LHC. Infrastructure works typically represent one third of the cost of major physics projects, so it's critical that the construction costs are well understood from the conceptual stage. This poster presents the first results of the feasibility studies for two potential ring colliders at CERN: the racetrack shaped Linac-Ring LHeC and an 80km circular tunnel to house the High Energy LHC (SHE-LHC) and the TLEP. Some of the key civil engineering challenges faced in such large scale projects are presented with particular emphasis on geology, design and risk.

MOPWO043

Hollow Electron Lens Simulation for the SPS

simulation, collimation, optics, proton

990

V. Previtali, G. Stancari, A. Valishev
Fermilab, Batavia, USA
S. Redaelli
CERN, Geneva, Switzerland

Funding: Fermilab is operated by Fermi Research Alliance, LLC, Contract No. DE-AC02-07CH11359 with the United States Dep. of Energy. This work was supported by the US LHC Accelerator Research Program (LARP).
The hardware of the Tevatron hollow electron lens, which has been used in the past for collimation purposes, is presently available. Possible applications of similar devices in the LHC are under evaluation, but a realistic date for installation of electron lenses in the LHC would be not earlier than the machine shutdown scheduled for 2018. We investigated the possibility of beam tests with the available hardware in the meantime in the SPS. This article aims to answer this question by presenting the results of dedicated numerical simulations.

MOPWO044

Numerical Simulations of a Hollow Electron Lens as a Scraping Device for the LHC

simulation, collimation, resonance, proton

993

V. Previtali, G. Stancari, A. Valishev
Fermilab, Batavia, USA
S. Redaelli
CERN, Geneva, Switzerland

Funding: Fermilab is operated by Fermi Research Alliance, LLC, Contract No.DE-AC02-07CH11359 with the United States Dep. of Energy. This work was partially supported by US LHC Accelerator Research Program(LARP)
The use of hollow electron beam lens for scraping high energy proton beams has been extensively tested at Fermilab's Tevatron collider. In order to evaluate a possible application of a similar a device in the LHC, a dedicated new routine has been implemented in the standard 6D tracking code used at CERN for the design of the LHC collimation system. The effects of a finite length cylinder of electrons encompassing the main proton beam and traveling in the opposite direction is described in the routine. Realistic electron distributions, including measured radial imperfections, have been included in the model. Various operating modes have been simulated for the 7 TeV machine operation with sextupoles and octupoles included. The loss rate caused by the electron lens has been studied through an extended simulation campaign; the obtained halo removal rates for the different electron lens operating modes are presented.

MOPWO054

The LHeC as a Higgs Boson Factory

linac, luminosity, factory, lepton

1017

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

The LHeC is designed to collide a new 60 GeV energy electron beam, from a 3-pass ERL, with the 7 TeV energy LHC proton beam. At the present target ep luminosity of 10³³cm^-2s^-1, the LHeC would produce a few 1000 Higgs bosons per year, allowing for precision coupling measurements, especially of the H –> b bbar decay in charged current deep inelastic scattering (ep –> nu H X). With a significant increase of the luminosity, rarer channels become accessible, as the charm decay. Here such an increase, to the level of 10³⁴cm^-2s^-1 or even beyond, is considered from a combination of improvements, namely with a smaller proton beam emittance, with a further reduction of the proton IP beta function, an increase of the proton bunch intensity and with doubling the lepton beam current, compared to the canonical values assumed in the CDR.

MOPWO059

Development of MATLAB-based Application Programs for the Optics Matching, Beam Steering, and Injection Conditioning in TPS Commissioning

linac, optics, injection, lattice

1025

M.-S. Chiu, H.-P. Chang, P.J. Chou, F.H. Tseng
NSRRC, Hsinchu, Taiwan

Taiwan Photon Source (TPS) is a third generation 3GeV synchrotron light source. Its first beam commissioning is scheduled in 2014. Intensive efforts are devoted to achieve efficient transportation of the first beam from the LINAC, passing through the LTB transfer line, and its injection into the booster ring. After the beam energy has been ramped up to 3GeV in booster, the beam is extracted to the BTS transfer line. At the end of BTS, the beam is injected into the storage ring and circulates around the storage ring. In order to achieve efficient beam transportation, we have developed various MATLAB-based commissioning tools for the optics matching of transfer lines, beam steering and injection conditioning of booster and storage ring.

MOPWO062

A Parallel Multi-objective Differential Evolution Algorithm for Photoinjector Beam Dynamics Optimization

controls, emittance, solenoid, gun

1031

J. Qiang, C.E. Mitchell, S. Paret, R.D. Ryne
LBNL, Berkeley, California, USA
Y.X. Chao
UCB, Berkeley, California, USA

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
In photoinjector design, there is growing interest in using multi-objective beam dynamics optimization to minimize the final transverse emittances and to maximize the final peak current of the beam. Most previous studies in this area were based on genetic algorithms. Recent progress in optimization suggests that the differential evolution algorithm could perform better in comparison to the genetic algorithm. In this paper, we propose a new parallel multi-objective optimizer based on the differential evolution algorithm for photoinjector beam dynamics optimization. We will discuss the numerical algorithm and some benchmark examples. This algorithm has the potential to significantly reduce the computation time required to reach the optimal Pareto solution.

MOPWO068

Simulating Electron Cloud Evolution using Modulated Dielectric Models

simulation, plasma, diagnostics, proton

1043

S.A. Veitzer, P. Stoltz
Tech-X, Boulder, Colorado, 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 the SCiDAC-3 project (DE-SC0008920)
Electron clouds can pose a serious threat to accelerator performance, and understanding cloud buildup and the effectiveness of different mitigation techniques can provide cost-saving improvements in accelerator design and fabrication. Microwave diagnostics of electron clouds are a non-destructive way to measure cloud buildup, but it is very difficult to measure the cloud density from spectral signals alone. Modeling travelling-wave rf diagnostics is very hard because of the large range of spatial and temporal scales that must be resolved to simulate spectra. New numerical models have been used to generate synthetic spectra for electron clouds when the cloud density is not changing, and results have been compared to theoretical results. Here we use dielectric models to generate spectra for clouds that evolve over many bunch crossings. We first perform detailed simulations of cloud buildup using kinetic particle models, and then use an equivalent plasma dielectric model corresponding to this density, at a finer time resolution, to compute spectra. The stability and accuracy of dielectric models that spectra can be accurately determined in these very long timescale simulations.

MOPWO071

Coherent Electron Cooling: Status of Single-Pass Simulations

simulation, FEL, ion, bunching

1049

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

Funding: US DOE Office of Science. Contracts DE-FC02-07ER41499, DE-FG02-08ER85182, DE-AC02-05CH11231.
Advances in nuclear physics depend on experiments that employ relativistic hadron accelerators with dramatically increased luminosity. Current methods of increasing hadron beam luminosity include stochastic cooling and electron cooling; however, these approaches face serious difficulties at the high intensities and high energies proposed for eRHIC *. Coherent electron cooling promises to cool hadron beams at a much faster rate**. A single pass of an ion through a coherent electron cooler involves the ion's modulating the charge density of a copropagating electron beam, amplification of the modulated electron beam in a free-electron laser, and energy correction of the ion in the kicker section. Numerical simulations of these three components are underway, using the parallel Vorpal framework and Genesis 1.3, with careful coupling between the two codes. Here we present validations of two components of the simulations: Adding bunching to an electron beam at the start of an FEL, and the time-dependent charge density modulation in the kicker.
* http://www.bnl.gov/cad/eRHIC/
** V.N. Litvinenko and Y.S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009).

MOPWO077

Design of the Proposed Low Energy Ion Collider Ring at Jefferson Lab

ion, booster, collider, interaction-region

1058

E.W. Nissen, F. Lin, V.S. Morozov, Y. Zhang
JLAB, Newport News, Virginia, USA

Funding: Supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The polarized Medium energy Electron-Ion Collider (MEIC) envisioned at Jefferson Lab will cover a range of center-of-mass energies up to 65 GeV. The present MEIC design could also allow the accommodation of low energy electron-ion collisions (LEIC) for additional science reach. This paper presents the first design of the low energy ion collider ring which is converted from the large ion booster of MEIC. It can reach up to 25 GeV energy for protons and equivalent ion energies of the same magnetic rigidity. An interaction region and an electron cooler designed for MEIC are integrated into the low energy collider ring, in addition to other required new elements including crab cavities and ion spin rotators, for later reuse in MEIC itself. A pair of vertical chicanes which brings the low energy ion beams to the plane of the electron ring and back to the low energy ion ring are also part of the design.

MOPWO078

A Harmonic Kicker Scheme for the Circulator Cooler Ring in the Medium Energy Electron-ion Collider

kicker, ion, collider, FEL

1061

E.W. Nissen, A. Hutton, A.J. Kimber
JLAB, Newport News, Virginia, USA

Funding: Supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
The current electron cooler design for the proposed Medium Energy Electron-Ion collider (MEIC) at Jefferson Lab utilizes a circulator ring for reuse of the cooling electron bunch up to 100 times to cool the ion beams. This cooler requires a fast kicker system for injecting and extracting individual bunches in the circulator ring. Such a kicker must work at a high repetition rate, up to 7.5 to 75 MHz depending on the number of turns in the recirculator ring. It also must have a very short rise and fall time (of order of 1 ns) such that it will kick an individual bunch without disturbing the others in the ring. Both requirements are orders of magnitude beyond the present state-of-the-art as well as the goals of other on-going kicker R&D programs such as that for the ILC damping rings. In this paper we report a scheme of creating this fast, high repetition rate kicker by combining RF waveforms at multiple frequencies to create a kicker waveform that will, for example, kick every eleventh bunch while leaving the other ten unperturbed. We also present a possible implementation of this scheme as well as discuss its limitations.

MOPWO080

GPU-optimized Code for Long-term Simulations of Beam-beam Effects in Colliders

simulation, luminosity, collider, damping

1064

Y. Roblin, V.S. Morozov, B. Terzić
JLAB, Newport News, Virginia, USA
M. Aturban, D. Ranjan, M. Zubair
ODU CS, Norfolk, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We report on the development of the new code for long-term simulation of beam-beam effects in particle colliders. The underlying physical model relies on a matrix-based arbitrary-order symplectic particle tracking for beam transport and the Bassetti-Erskine approximation for beam-beam interaction. The computations are accelerated through a parallel implementation on a hybrid GPU/CPU platform. With the new code, a previously computationally prohibitive long-term simulations become tractable. We use the new code to model the proposed medium-energy electron-ion collider (MEIC) at Jefferson Lab.

MOPWO081

The Scheme of Beam Synchronization in MEIC

ion, collider, proton, SRF

1067

Y. Zhang, Y.S. Derbenev, A. Hutton
JLAB, Newport News, Virginia, USA

Funding: Supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
Synchronizing colliding beams at single or multiple collision points is a critical R&D issue in the design of a medium energy electron-ion collider (MEIC) at Jefferson Lab. The path-length variation due to changes in the ion energy, which varies over 20 to 100 GeV, could be more than several times the bunch spacing. The scheme adopted in the present MEIC baseline is centered on varying the number of bunches (i.e., harmonic number) stored in the collider ring. This could provide a set of discrete energies for proton or ions such that the beam synchronization condition is satisfied. To cover the ion energy between these synchronized values, we further propose to vary simultaneously the electron ring circumference and the frequency of the RF systems in both collider rings. We also present in this paper the requirement of frequency tunability of SRF cavities to support the scheme.

MOPWO083

LEIC - A Polarized Low Energy Electron-ion Collider at Jefferson Lab

ion, collider, booster, proton

1070

Y. Zhang, Y.S. Derbenev, A. Hutton, G.A. Krafft, R. Li, F. Lin, V.S. Morozov, E.W. Nissen, R.A. Rimmer, H. Wang, S. Wang, B.C. Yunn, H. Zhang
JLAB, Newport News, Virginia, USA
M.K. Sullivan
SLAC, Menlo Park, California, USA

Funding: Supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177 and DE-AC02-06CH11357.
A polarized electron-ion collider is envisioned as the future nuclear science program at JLab beyond the 12 GeV CEBAF. Presently, a medium energy collider (MEIC) is set as an immediate goal with options for a future energy upgrade. A comprehensive design report for MEIC has been released recently. The MEIC facility could also accommodate electron and proton/ion collisions in a low CM energy range, covering proton energies from 10 to 25 GeV and ion energies with a similar magnetic rigidity, for additional science reach. In this paper, we present a conceptual design of this low energy collider, LEIC, showing its luminosity can reach above 10³³ cm^-2s⁻¹. The design specifies that the large booster of the MEIC is converted to a low energy ion collider ring with an interaction region and an electron cooler integrated into it. The design provides options for either sharing the detector with the MEIC or a dedicated low energy detector in a third collision point, with advantages of either a minimum cost or extra detection parallel to the MEIC operation, respectively. The LEIC could be positioned as the first and low cost phase of a multi-stage approach to realize the full MEIC.

MOPWO088

Semi-analytical Description of the Modulator Section of the Coherent Electron Cooling

plasma, shielding, hadron, simulation

1082

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

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
We discuss the theoretical description of the modulator section of the coherent electron cooling (CeC)*, the modern realization of the stochastic electron cooling, where the electron beam serves as a modulator and a kicker, i.e., it records the information about the hadron beam via electron density perturbations resulting from the shielding of the hadrons and then accelerates or decelerates hadrons by its electric field with respect to their velocities. To analyze the performance of the CeC shielding of a hadron in an electron beam should be computed with high precision. We propose a solution of this problem via Fourier and Laplace transforms for 1D, 2D and 3D plasmas. In some cases there are fully analytical solutions, which gave an opportunity to test semi-analytical ones involving numerical evaluations of the inverse integral transforms. Having its own practical value this solution will also serve as a testing ground for our general solution via numerical treatment of the integral equations applicable for the realistic case of the finite beam**.
* V. N. Litvinenko, Y. S. Derbenev, Phys. Rev. Lett. 102, 114801 (2009).
** A. Elizarov, V. Litvinenko, G. Wang, IPAC'12 Proceedings, weppr099 (2012).

TUYB102

Summary of the ILC R&D and Design

positron, linac, damping, cavity

1101

B.C. Barish
CALTECH, Pasadena, California, USA

This talk should provide a summary of the main activities of ILC-GDE since 2005, and an overview of the Technical Design Report with prospects for the next steps for the future.

Slides TUYB102 [6.544 MB]

TUOCB101

Argonne Wakefield Accelerator (AWA): A Facility for the Development of High Gradient Accelerating Structures and Wakefield Measurements

wakefield, acceleration, linac, gun

1111

M.E. Conde, S.P. Antipov, D.S. Doran, W. Gai, C.-J. Jing, R. Konecny, W. Liu, J.G. Power, E.E. Wisniewski, Z.M. Yusof
ANL, Argonne, USA
S.P. Antipov, C.-J. Jing, R. Konecny
Euclid TechLabs, LLC, Solon, Ohio, USA
E.E. Wisniewski, Z.M. Yusof
Illinois Institute of Technology, Chicago, Illinois, USA

Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC02-06CH11357.
The recently upgraded AWA facility is being commissioned. Operation of the new L-Band RF gun with a Cesium Telluride photocathode will generate long electron bunch trains, with high charge per bunch (up to 100 nC). The six new linac tanks will boost the beam energy to 75 MeV, making it an extremely well suited drive beam to excite wakefields in structures. One of the main goals of the facility is to generate RF pulses with GW power levels, corresponding to accelerating gradients of hundreds of MV/m and energy gains on the order of 100 MeV per structure. A key aspect of the studies and experiments carried out at the AWA facility is the use of relatively short RF pulses (15 – 25 ns), which is believed to mitigate the risk of breakdown and structure damage.

Slides TUOCB101 [3.416 MB]

TUOCB102

SPARC_LAB Recent Results

laser, plasma, photon, FEL

1114

M. Ferrario, D. Alesini, M.P. Anania, A. Bacci, M. Bellaveglia, M. Castellano, E. Chiadroni, D. Di Giovenale, G. Di Pirro, A. Drago, A. Esposito, A. Gallo, G. Gatti, A. Ghigo, T. Levato, A. Mostacci, L. Palumbo, A.R. Rossi, B. Spataro, C. Vaccarezza, F. Villa
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
INFN-Roma II, Roma, Italy
G. Dattoli, E. Di Palma, L. Giannessi, A. Petralia, C. Ronsivalle, V. Surrenti
ENEA C.R. Frascati, Frascati (Roma), Italy
C. De Martinis
INFN/LASA, Segrate (MI), Italy
R. Faccini
INFN-Roma, Roma, Italy
M. Gambaccini
INFN-Ferrara, Ferrara, Italy
D. Giulietti
UNIPI, Pisa, Italy
L.A. Gizzi, L. Labate
CNR/IPP, Pisa, Italy
S. Lupi
Università di Roma I La Sapienza, Roma, Italy
V. Petrillo, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
J.V. Rau
ISM-CNR, Rome, Italy
G. Turchetti
Bologna University, Bologna, Italy

A new facility named SPARC_LAB (Sources for Plasma Accelerators and Radiation Compton with Lasers and Beams) has been recently launched at the INFN National Labs in Frascati, merging the potentialities of the an ultra-brilliant electron beam photoinjector and of a high power Ti:Sa laser. The test facility is now completed, hosting a 150 MeV high brightness electron beam injector which feeds a 12 meters long undulator. Observation of FEL radiation in variuous configurations has been performed. In parallel to that a 200 TW laser that is linked to the linac and devoted to explore laser-matter interaction, in particular with regard to laser-plasma acceleration of electrons (and protons) in the self injection and external injection modes. The facility will be also used for particle driven plasma acceleration experiments (the COMB experiment). A Thomson scattering experiment coupling the electron bunch to the high-power laser to generate coherent monochromatic X-ray radiation is also in the commissioning phase. We report in this paper the recent results obtained at the SPARC_LAB facility.

Slides TUOCB102 [12.874 MB]

TUODB101

Studies on An S-band Bunching System with Hybrid Buncher

bunching, linac, cavity, gun

1120

S. Pei, O. Xiao
IHEP, Beijing, People's Republic of China

Generally, a standard bunching system is composed by a SW pre-buncher, a TW buncher and a standard accelerating section. However, there is one way to simplify the whole system to some extent by using the hybrid buncher, which is a combined structure of the SW pre-buncher and the TW buncher. Here the beam dynamics studies on an S-band bunching system with hybrid buncher is presented, simulation results shows that similar beam performance can be obtained at the linac exit by using this kind of bunching system rather than the standard one. In the meantime, the structure design of the hybrid buncher is also described. Furthermore, the standard accelerating section can also be integrated with the hybrid buncher, this can further simplify the bunching system and lower the construction cost.

Slides TUODB101 [22.120 MB]

TUXB201

Short-pulse Operation of Storage Ring Light Sources

radiation, storage-ring, photon, optics

1129

A.-S. Müller
KIT, Karlsruhe, Germany

Short-pulse operation of synchrotron light source storage rings can be useful for both the production of IR and THz-band radiation and high repetition rate pump-probe science in the X-ray regime. Different approaches to short-pulse generation include low-alpha optics configurations, two-frequency RF potential manipulation, laser-induced femtoslicing, longitudinal crab-cavity deflection and pseudo-bunch operation with a fast kicker to isolate a single bunch. This talk should review each of these techniques and discuss implications for machine operation in terms of pulse length, beam intensity, beam stability, pulse repetition rate, output radiation beam quality and potential applications.

Slides TUXB201 [12.058 MB]

TUOAB201

Ultra-Short X-ray Pulse Generation by Electron Beam Slicing in Storage Rings

storage-ring, linac, emittance, photon

1134

L.-H. Yu, F.J. Willeke
BNL, Upton, Long Island, New York, USA

Funding: Department of Energy, USA
We propose a new method to generate ultra-short x-ray pulses using focused short low energy (5-10MeV) electron bunch to slice a short electron bunch from the electron bunches in a synchrotron radiation storage ring. When the low energy electron bunch crosses from top the high energy electron bunch at right angle, its coulomb force will kick a short slice of high energy electrons away from the core of the storage ring electron bunch. When the low energy electron bunch (about 50 pC) is focused to about 50 micron size and compressed to about 150fs bunch length and is positioned on top of the high energy electron bunch by a distance about 30 micron, the coulomb force is sufficient to give a kick vertically to the electrons within a short slice of the storage ring bunch about 200 fs long with a deflection about 4 micro-radian. This is sufficient to deflect the slice away from the core by a separation of 5 times the angular divergence of the beam. The separated slice when passing through an undulator, will radiate ulstra-short x-ray pulses at about 200 fs. We discuss the advantages and challenges of this new method. We provide data to demonstrate the feasibility of this method.

Slides TUOAB201 [1.578 MB]

TUOCB201

Recent Developments of Novel Beam Diagnostics at the ESRF

dipole, vacuum, diagnostics, injection

1143

K.B. Scheidt
ESRF, Grenoble, France

A number of rather novel and particular electron beam diagnostics have seen their development in 2012 for the ESRF Storage Ring. A vertical Beam Halo detector that measures the bunch population at millimetres, i.e. hundreds of σs of nominal beam size, away from the central core. This measurement is based on X-ray synchrotron radiation from a bending magnet and is totally non-destructive to the electron beam itself. Another diagnostic use of the very hard X-rays available from the bending magnets is the detection of electron beam energy fluctuations. The detector hardware is simple and in-expensive and has shown a resolution of energy fluctuations of less than 10ppm. Also a single orbit turn measurement of the injected beam shape and size is now possible through the use of visible synchrotron light combined with a fast gateable intensifier, which can be triggered on any of the desired orbit turns after injection. Detailed results of each of these new diagnostics will be presented.

Slides TUOCB201 [1.511 MB]

TUPEA001

Generation of Anomalous Intensive Transition Radiation for FEL

radiation, dipole, lattice, polarization

1161

K.B. Oganesyan, A.S. Gevorkyan, E.M. Sarkisyan
ANSL, Yerevan, Armenia
Y. Rostovtsev
University of North Texas, Denton, Texas, USA

The 3D spin-glass system in the external standing electromagnetic field is considered. It is shown on an example of amorphous quartz, under the influence of a standing microwave field, at its certain parameters, superlattice is created in the medium where difference in values of dielectric constants of neighboring layers can be up to third order. Note that this superlattice exists during the nanosecond however it is sufficient for using it as a radiator for generation of transition radiation by relativistic electrons.

TUPEA005

Effects of Quantum Diffusion on Electron Trajectories and Spontaneous Synchrotron Radiation Emission

radiation, photon, undulator, synchrotron

1170

I.V. Agapov, G. Geloni
XFEL. EU, Hamburg, Germany
O.V. Chubar
BNL, Upton, Long Island, New York, USA

For various cases, e.g. in the long undulator sections of the European XFEL, quantum diffusion and energy loss have a noticable effect on the electron trajectory, which in turn affects the properties of the emitted radiation. We discuss approaches to modelling the electron dynamics taking this into account and the effect it has on spontaneous radiation emission.

TUPEA007

Spontaneous Radiation Calculations for the European XFEL

undulator, radiation, emittance, FEL

1176

I.V. Agapov, G. Geloni
XFEL. EU, Hamburg, Germany
O.V. Chubar
BNL, Upton, Long Island, New York, USA
M. Scheer, M. Titze
HZB, Berlin, Germany
N.V. Smolyakov, S.I. Tomin
NRC, Moscow, Russia

Calculating spontaneous radiation emission from long undulators such as those present in the European XFEL, being background to FEL radiation, is still important for several diagnostics and science cases. For realistic setups, and including effects of electron beam focusing, emittance and energy spread in the electron beam, these calculations should be performed numerically. We present these calculations for several electron beam and undulator parameters performed by various codes. Sensitivity of different spontaneous radiation characteristics, in various collection schemes, to the electron beam and undulator magnetic field parameters is studied

TUPEA008

Physics of the AWAKE Project

plasma, wakefield, laser, injection

1179

P. Muggli, E. Oz, R. Tarkeshian
MPI, Muenchen, Germany
C. Bracco, E. Gschwendtner, A. Pardons
CERN, Geneva, Switzerland
A. Caldwell, O. Reimann
MPI-P, München, Germany
K.V. Lotov
BINP SB RAS, Novosibirsk, Russia
A.M. Pukhov
HHUD, Dusseldorf, Germany
J. Vieira
IPFN, Lisbon, Portugal
M. Wing
UCL, London, United Kingdom

The goal of the AWKAKE collaboration is the study of plasma wakefields driven by proton (p⁺) bunches through experiments, simulations and theory. Proton bunches are interesting wakefield drivers because they can be ultra-relativistic (TeVs/p⁺) and carry large amounts of energy (>kJ). It was demonstrated in simulations* that acceleration of an electron (e-) bunch from 10GeV to >500GeV can be achieved in ~500m of plasma driven by a 1TeV, 100micron-long, bunch with 10¹¹ p+. Such short p⁺ bunches do not exist today. It was suggested** that a p⁺ bunch long compared to the plasma period can transversely self-modulate and resonantly drive wakefields to large amplitudes (~GV/m). Initial experiments based on self-modulation instability (SMI) will use single 12cm-long CERN SPS bunches with 1-3·10¹¹, 450GeV p⁺ to study physics of SMI. With a plasma density of 7·10¹⁴/cc the plasma wave and modulation period is 1.3mm. The SMI saturates after ~3m with amplitude in the GV/m range. Later a low energy (~10MeV) witness e^- bunch will be injected at the SMI saturation point. Energy gain over ~7m of plasma can reach the GeV level. Translation from physics to experimental plan and setup will be presented.
* A. Caldwell et al., Nature Physics 5, 363 (2009)
** N. Kumar et al., Phys. Rev. Lett. 104, 255003 (2010)

TUPEA010

FERMI Seeded FEL Progress Report

FEL, laser, undulator, free-electron-laser

1182

M. Svandrlik, E. Allaria, F. Bencivenga, C. Callegari, F. Capotondi, D. Castronovo, P. Cinquegrana, P. Craievich, I. Cudin, G. D'Auria, M. Dal Forno, M.B. Danailov, R. De Monte, G. De Ninno, A.A. Demidovich, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, P. Finetti, L. Fröhlich, P. Furlan Radivo, G. Gaio, L. Giannessi, M. Kiskinova, G.L. Loda, M. Lonza, B. Mahieu, N. Mahne, C. Masciovecchio, F. Parmigiani, G. Penco, O. Plekan, M. Predonzani, E. Principi, L. Raimondi, F. Rossi, L. Rumiz, C. Scafuri, C. Serpico, P. Sigalotti, S. Spampinati, C. Spezzani, L. Sturari, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Zangrando, M. Zangrando
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
P. Craievich
PSI, Villigen PSI, Switzerland
B. Mahieu
CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France

Funding: Work supported in part by the Italian Ministry of University and Research under grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3
FERMI, the seeded Free Electron Laser located at the Elettra laboratory in Trieste, Italy, welcomed in December 2012 the first external users on the FEL-1 line. This line is based on a single stage of High Gain Harmonic Generation (HGHG), seeded by a UV laser, and covers wavelengths between 80 and 20 nm. The photon energy reached more than 300 μJ. The second FEL line, FEL-2, covering the lower wavelength range between 20 and 4 nm thanks to a double stage cascaded HGHG scheme, has generated its first coherent photons in October 2012. This is the first experimental demonstration of a seeded free electron laser configured as a two stages cascade operating in the "fresh bunch injection” mode, where the second stage is seeded by the light produced by the first stage. This paper describes the status of the operation and user experiments with FEL-1 and reports about the progress in the commissioning of FEL-2.

TUPEA011

Double Stage Seeded FEL with Fresh Bunch Injection Technique at FERMI@Elettra

FEL, laser, undulator, photon

1185

S. Di Mitri, E. Allaria, D. Castronovo, P. Cinquegrana, P. Craievich, G. D'Auria, M.B. Danailov, G. De Ninno, A.A. Demidovich, B. Diviacco, W.M. Fawley, M. Ferianis, E. Ferrari, L. Fröhlich, G. Gaio, L. Giannessi, R. Ivanov, B. Mahieu, N. Mahne, I. Nikolov, F. Parmigiani, G. Penco, L. Raimondi, C. Serpico, P. Sigalotti, S. Spampinati, C. Spezzani, M. Svandrlik, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, D. Zangrando, M. Zangrando
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
D. Gauthier
University of Nova Gorica, Nova Gorica, Slovenia

During the month of October 2012 the commissioning of the light source FEL-2 at FERMI was successfully concluded. Fermi FEL-2 is the first seeded FEL operating with a double stage cascade in the "fresh bunch injection" mode*. The two stages are two high gain harmonic generation FELs where the first stage is seeded by the 3rd harmonic of a Ti:Sa laser system, which is up converted to the 4th-12th harmonic. The output of the first stage is then used to seed the second stage. A final wavelength of 10.8 nm was obtained as the 24th harmonic of the seed wavelength at the end of the two frequency conversion processes, demonstrating that the FEL is capable of producing single mode narrow bandwidth pulses with an energy of several tens ofμjoules. We report on the experimental characterisation of the FEL performances in this configuration.
* I. Ben-Zvi, K. M. Yang, L. H. Yu, ”The ”fresh-bunch” technique in FELs”, NIM A 318 (1992), p 726-729

TUPEA013

Present Status of Mid-infrared Free Electron Laser Facility in Kyoto University

FEL, gun, undulator, cavity

1190

H. Zen, Y.W. Choi, H. Imon, M. Inukai, T. Kii, R. Kinjo, T. Konstantin, K. Masuda, K. Mishima, H. Negm, H. Ohgaki, K. Okumura, M. Omer, S. Shibata, K. Shimahashi, K. Yoshida
Kyoto University, Institute for Advanced Energy, Kyoto, Japan

A Mid-Infrared Free Electron Laser (MIR-FEL) facility named as KU-FEL has been constructed for energy science in Institute of Advanced Energy, Kyoto University*. The accelerator of KU-FEL consists of an S-band 4.5-cell thermionic RF gun, a Dog-leg section for energy filtering, a 3-m traveling-wave type accelerator tube, 180-degree arc section for bunch compression and a hybrid undulator. We have already succeeded in lasing of the FEL from 5.5 to 14.5 micro-meter. Present status and recent activity for the FEL development will be presented in the conference.
*H. Zen, et al., Infrared Physics & Technology, vol.51, 382-385.

TUPEA016

Relativistic Theory for Laser-ion Acceleration

ion, acceleration, plasma, laser

1193

Y.S. Huang, Y.J. Shi, X.Z. Tang, N.Y. Wang
CIAE, Beijing, People's Republic of China

Funding: The Key Project of Chinese National Programs for Fundamental Research (973 Program) under contract No. 2011CB808104 and the Chinese National Natural Science Foundation under contract No. 11105233.
An analytical relativistic model is proposed to describe the relativistic ion acceleration in the interaction of ultra-intense laser pulses with thin-foil plasmas. It is found that there is a critical value of the ion momentum to make sure that the ions are trapped by the light sail and accelerated in the radiation pressure acceleration (RPA) region. If the initial ion momentum is smaller than the critical value, that is in the classical case of RPA, the potential has a deep well and traps the ions to be accelerated. There is a new ion acceleration region different from RPA, called ultra-relativistic acceleration, if the ion momentum exceeds the critical value. In this case, ions will experience a potential downhill. The dependence of the ion momentum and the self-similar variable at the ion front on the acceleration time has been obtained. The critical conditions of the laser and plasma parameters which identify the two acceleration modes have been achieved. No matter RPA or ultra-relativistic acceleration, the potential difference is a constant, which dedicates the maximum ion energy.

TUPEA017

Monoenergetic Electron Beams with Ultralow Normalized Emittance Generated from Laser-Gas Interaction

laser, plasma, emittance, simulation

1196

D.Z. Li, J. Gao, K. Huang, J. Jiarui, Y. Ma
IHEP, Beijing, People's Republic of China
L.M. Chen, W.C. Yan
Institute of Physics, Chinese Academy of Sciences, Beijing, People's Republic of China

High quality electron bunches are generated by using 2 TW, 80 fs, high contrast laser pulses interacting with helium gas targets. In optimized condition, we get tens MeV monoenergetic electron beams with small energy spread and the normalized emittance 0.07π mm·mrad. Due to its ultra small emittance and high initial energy, such bunch is very suitable for high current linear accelerators.

TUPEA019

Proton Acceleration driven by High Energy Density Electrons

proton, laser, acceleration, plasma

1202

S. Zhao, C. Chao, J.E. Chen, H.Z. Fu, Y.X. Geng, C. Lin, B. Liu, H. Wang, X.Q. Yan
PKU, Beijing, People's Republic of China

Resonance Electrons Driving Ion Acceleration S. Zhao, C. Lin, X. Q. Yan Institute of Heavy Ion Physics, Peking University Proton acceleration driven by resonance electrons is proposed. Energetic electron beam generated through direct laser acceleration in the near critical dense plasma is dense and directional. When interacting with a thin foil target, resonance electrons can transmit the target and drive periodical electrostatic field at the back surface, therefore protons are more efficiently accelerated in a much longer distance in propagation direction of resonance electrons, compared to the classical target normal sheath acceleration. For a Gaussian laser pulse with pulse duration of 80fs, peak intensity I=1.38*10⁸W/cm² , the cutoff energy of the output collimated proton beam is 14MeV, enhanced by a factor of 3 or 4. The scaling law predicts hundreds MeV Proton beam can be generated in laser intensity of 10²⁰W/cm².

TUPEA021

Calculation of Wakefields in Plasma Filled Dielectric Capillaries Generated by a Relativistic Electron Beam

plasma, wakefield, positron, collider

1205

C. Li, W. Gai
ANL, Argonne, USA
C. Li, C.-X. Tang, H. Zha
TUB, Beijing, People's Republic of China

In this paper we give an analytical solution of TM0n mode for wakefields generated by a relativistic electron beam passing through plasma-filled capillary waveguides. The numerical solution shows that the fields of TM0n modes could not be ignored when the plasma wave length is comparable with the effective radius of the capillary tube, which means that the boundaries are not shielded completely by plasma. Numerical examples are given in several typical cases.

TUPEA028

Echo-enabled Harmonic Generation based on Hefei Storage Ring

FEL, bunching, laser, storage-ring

1208

H.T. Li, W.W. Gao, Q.K. Jia, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Echo-Enabled Harmonic Generation (EEHG) has been proposed and experimently demonstrated recently. In this paper, we numerically investigate the possibility of operating EEHG based on Hefei storage ring, which has a short circumference and a small momentum compaction factor. The difference to other similar reserch is that we use the whole ring as the first dispersive section and an optical klystron as the second one.

TUPEA029

Theory Calculation of PASER in Gas Mixture Active Medium

resonance, laser, wakefield, plasma

1211

X.F. Tian, C.-F. Wu
USTC/NSRL, Hefei, Anhui, People's Republic of China

In the PASER (particle acceleration by stimulated emission of radiation), the energy stored in an active medium transferred directly to the electron beam passing through in discrete amounts by emitting a photon when the bounded electron returns from upper to lower energy state. In this paper, the wake-field generated by a bunch of electrons traversing in an active medium has been discussed. The calculations of the development of amplitude for gas mixture active medium about CO2 and ArF were made respectively. The results show that the gradient can reach around 1GeV/m. In addition, the electron energy gain occurring as a train of electron micro-bunches traversing in gas mixture was analyzed by a two dimension model. The train of micro-bunches can obviously gain energy from the active medium and the energy exchange is linearly proportional to the interaction length d. The influence of the bunch figure and other quantities on the energy exchange occurring as a train of electron micro-bunches traversing CO2 gas mixture were investigated when the interaction length is 0.5m. The results illustrate that maximum electron energy gain can be obtained by the train of micro-bunches with optimized parameters.

TUPEA030

High Brightness and Fully Coherent X-ray Pulses from XFELO Seeded High-gain FEL Schemes

FEL, radiation, cavity, undulator

1214

H.X. Deng, C. Feng
SINAP, Shanghai, People's Republic of China

The successful operation of the hard x-ray self-seeding experiment at the LCLS opens the era of fully coherent hard x-ray free electron lasers (FELs). However, the shot-to-shot radiation fluctuation is still a serious issue. In this paper, high-gain, single-pass x-ray FEL schemes seeded by the narrow bandwidth radiation signal from an x-ray FEL oscillator were proposed and investigated, which are expected to generate high brightness, fully coherent and stable x-ray pulse. A simple model has been developed to figure out the temporal and the spectral structures of the output pulses in x-ray FEL oscillator. And options using two synchronized accelerators and using one accelerator were considered, respectively.

TUPEA033

Proposals for Chirped Pulse Amplification in HGHG and CHG at SDUV-FEL

FEL, laser, radiation, undulator

1217

C. Feng, L. Shen, D. Wang, D. Xiang, M. Zhang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

In this paper, a proposal to generate intense ultra-short free-electron laser (FEL) pulses at Shanghai deep ultraviolet FEL (SDUV-FEL) by combining the chirped pulse amplification (CPA) technique with the high-gain harmonic generation (HGHG) technique is presented. In this proposal, a frequency chirped seed pulse obtained by stretching an ultra-short laser pulse is first used to create frequency-chirped bunching at the laser harmonics in an electron beam; then the frequency chirped harmonic radiation is amplified by an energy chirped electron beam; finally the output radiation pulse which inherits the properties of the seed pulse is compressed to provide an ultra-intense ultra-short radiation pulse. The feasibility and performance of this CPA-HGHG scheme are studied with start-to-end simulations using the parameters of the SDUV-FEL.

TUPEA035

Plasma Effect in the Longitudinal Space Charge Induced Microbunching Instability

plasma, impedance, space-charge, background

1220

D. Huang, Q. Gu
SINAP, Shanghai, People's Republic of China
K.Y. Ng
Fermilab, Batavia, USA

Funding: National Science Foundation of China (NSFC), grant No. 11275253, and US DOE, contract DE-FG02-92ER40747.
In many cases, the longitudinal space charge (LSC) is a dominant factor to bring in the microbunching instability in the LINAC of a Free-Electron-Laser (FEL) facility. The current model of LSC impedance* derived from the fundamental electromagnetic theor** is widely used to explain the physics of the LSC-induced microbunching instability***. However, in the case of highly bright electron beams, the plasma effect starts to play a role. In this paper, the basic model of the LSC impedance including the plasma effect is built up by solving the Vlasov and Poisson equations in 6 dimensional phase space, and the investigation is done to study the modification to the gain of the instability based on the model. The solutions indicate that the gain does not only depend on the spatial information of the beam, but also on the velocity (momentum) and time information. The comparison of the gains of the microbunching instability in the LINAC of Shanghai soft X-ray Free Electron Laser Facility (SXFEL) computed by various methods is also given and the discrepancy is illustrated.
* Marco Venturini, Phys. Rev. ST Accel. Beams 11, 034401 (2008)
** J. D. Jackson, Classical Electrodynamics (Wiley, 1999)
*** Z. Huang, et. al., Phys, Rev. ST Accel. Beams 7, 074401 (2004)

TUPEA038

Pre-chirp Control Broadband Non-collinear Optical Parametric Amplifier for the Future Laser Weak-field Accelerator

controls, laser

1223

L. Shen, C. Feng, L. Feng, D. Wang, H.F. Yao, W.Y. Zhang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

Ultra-short pulse has been proved to be a very useful tool for accelerating electron close to GeV now. But limited by gain narrowing effect, conventional CPA technology is quite hard to get less than 30fs at high energy level. Non-collinear optical parametric amplification (NOPA) looks more and more attractive for generating super-broadbandwidth pulses which is possible to be compressed to ultra-short pulses. Previous NOPAs, pumped by 400nm pulses, were using BBO crystals to reach shorter signal pulse durations. But the associated spectral bandwidths are still strongly linked with higher order nonlinear effects. which make it quite difficult to get higher energy with short pulse duration. Here we proposed to use pre-chirped few nm bandwidths around 515nm pumped pulses to amplify ultra-short pulses centered at 800nm. In our setup, we have found just one dramatical geometry configuration which support that we have possibility to get amplification from 720nm to 900nm, which will support to less than 10fs by well re-compression. This design is well adapted for BBO crystals. But the idea could be used also for other crystals.

TUPEA043

Linac Design for Nuclear Data Measurement Facility

linac, neutron, cavity, target

1229

M. Zhang, W. Fang, Q. Gu, X. Li
SINAP, Shanghai, People's Republic of China

Pulsed neutrons based on an electron linear accelerator (linac) are effective for measuring energy dependent cross-sections with high resolution by using the time-of-flight (TOF) technique. In this paper, we describe the 15-MeV linac design for the Nuclear Data project in Shanghai Institute of Applied Physics (SINAP). The linac has three operating modes and the maximum average power is 7.5kW. We describe the characteristics of the linac and the study of the beam dynamics is also presented.

TUPEA044

The Design of Control System for the Optical Cavity Adjuster of a FEL-THz Source

controls, cavity, FEL, undulator

1232

X. Liu, Q. Fu, B. Qin, P. Tan, C. Wang, Y.Q. Xiong, J. Yang, H. Zeng
HUST, Wuhan, People's Republic of China

The optical cavity adjuster is an important sub-system in a FEL-THz source, which is used to adjust the position and angle of the optical cavity with a high precision. In view of the requirements of the optical cavity adjuster of the FEL-THz source, this paper presents the design of the control system of the optical cavity adjuster. The design of the control system based on a PC and a motion controller is adopted. The motion controller controls high-precision linear stage to adjust linear direction and picomotors are controlled to enable the adjustment of roll and yaw. According to relevant calculation, the range of linear direction and the accuracy can be reached at ±3mm and 0.2~0.5μm; the range of the adjustment of roll and yaw and the accuracy can be reached at ±2° and 20″. In summing up it can be stated that the design meets the requirements and it also lays the foundation for engineering on developing the optical cavity adjuster.

TUPEA045

Self-Modulation and Hosing Instability of Slac Electron and Positron Bunches in Plasmas

plasma, positron, wakefield, simulation

1235

J. Vieira, N.C. Lopes
Instituto Superior Tecnico, Lisbon, Portugal
E. Adli, S.J. Gessner, M.J. Hogan, S.Z. Li, M.D. Litos
SLAC, Menlo Park, California, USA
Y. Fang
USC, Los Angeles, California, USA
C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi
UCLA, Los Angeles, California, USA
P. Muggli
MPI, Muenchen, Germany
O. Reimann
MPI-P, München, Germany
L.O. Silva
IPFN, Lisbon, Portugal

Funding: This work has been partially supported by Humboldt Foundation.
The understanding of the self-modulation (SMI) and hosing (HI) instabilities is critical for the success of the upcoming proton driven plasma wakefield acceleration experiments at CERN*. The use of long SLAC electron and positron bunches provides the possibility of understanding experimentally the interplay between SMI and HI. In this work we perform particle-in-cell simulations with the code OSIRIS with parameters that will be available for experiments at SLAC in 2013. We show that the SMI of 20 GeV lepton bunches can grow and saturate in less than 15 cm. Up to 8 GeV energy gain/loss could be observed after a meter long plasma. The HI can also be effectively mitigated by seeding the SMI using bunches with short rise times**. We also show analytically and numerically that in the linear regime and after saturation of the SMI the HI can be suppressed by a plasma-BNS damping analogue. Several diagnostics that could be used in experiments to measure the SMI development and these effects are also explored.
*G. Xia et al., J. Plasma Phys., 1-7 (2012).
**J. Vieira et al., Phys. Plasmas 19, 063105 (2012).

TUPEA048

Simulation of Self-modulating Particle Beams in Plasma Wakefield Accelerators

plasma, wakefield, simulation, proton

1238

K.V. Lotov
BINP SB RAS, Novosibirsk, Russia
K.V. Lotov, A. Sosedkin
NSU, Novosibirsk, Russia
E. Mesyats
ICM&MG SB RAS, Novosibirsk, Russia

Funding: The Ministry of education and science of Russia, project 14.B37.21.0784.
Controlled self-modulation of long proton or electron beams is a new trend in plasma wakefield acceleration which sets a new goal for simulation codes. Long interaction lengths (tens of meters), long beams (up to hundred of plasma wave periods), motion of plasma ions, and violation of fluid approximation are factors that makes the problem too heavy for general purpose codes. Only specialized codes can attack this problem in real geometry. We describe recent upgrades of the code LCODE which enabled simulations of long dense proton beams and report results of numerical studies of proton beam-plasma interaction in the context of AWAKE project.

TUPEA049

Wakefields of Ultrarelativistic Bunches in Cold Magnetized Plasma

wakefield, plasma, radiation, acceleration

1241

S.N. Galyamin, A.V. Tyukhtin
Saint-Petersburg State University, Russia

Funding: Work is supported by Russian Foundation for Basic Research and the Dmitry Zimin "Dynasty" Foundation.
We deal with electromagnetic field of various bunches moving in a cold magnetized plasma along the external magnetic field. The main attention is paid to the case of ultrarelativistic motion. First, for the case of point charge, we obtain the approximate formulas which are valid in the far-field zone and in the vicinity of the charge trajectory. These expressions predict the beating behavior of the far field and the harmonic behavior of the near field. Moreover, the magnitude of the longitudinal components of both electric and magnetic field as well as the transversal electric field possess singularity on the charge trajectory. Second, using formulas for the point charge field as Green function, we develop an effective algorithm for calculation of the bunch wakefield. Plots of wakefields produced by typical bunches are given. Prospects of using the bunch field properties for further development of the plasma wakefield acceleration technique are discussed.

TUPEA050

Extension of the MAX IV Linac for a Free Electron Laser in the X-ray Region

linac, FEL, undulator, emittance

1244

F. Curbis, N. Čutić, M. Eriksson, O. Karlberg, F. Lindau, A. Mak, E. Mansten, S. Thorin, S. Werin
MAX-lab, Lund, Sweden

The 3 GeV linac for the MAX IV laboratory is currently under construction in Lund (Sweden). As full energy injector for the MAX IV rings, a thermionic gun will be used to create electrons. However a photocathode gun planned for a short pulse facility (SPF) will deliver small emittance and ultra-short electron bunches that will be suitable to also drive a Free-Electron Laser. Moreover extending the linac energy with 1 or 2 GeV will give the opportunity to get closer to 1 Angstrom radiation with much more flexibility and better performances. Given these opportunities at the MAX IV laboratory, a free electron laser is envisaged in the long term perspective of the facility. In this study we investigate the case of a 5 GeV machine which can produce radiation in the X-ray region. The FEL design will benefit from the implementation of self-seeding, to enhance stability of the central wavelength and spectral bandwidth. Tapering along variable gap undulators will help to extract the maximum photon flux and increase the brilliance of the source. Among others, this kind of machine would be suitable for time resolved experiments and imaging.

TUPEA053

Feasibility Study of the AWAKE Facility at CERN

proton, plasma, laser, wakefield

1253

E. Gschwendtner, C. Bracco, B. Goddard, M. Meddahi, A. Pardons, E.N. Shaposhnikova, H. Timko, F.M. Velotti, H. Vincke
CERN, Geneva, Switzerland

Plasma Wakefield acceleration is a rapidly developing field which appears to be a promising candidate technology for future high-energy accelerators. The Proton Driven Plasma Wakefield Acceleration has been proposed as an approach to eventually accelerate an electron beam to the TeV energy range in a single plasma section. To verify this novel technique, a proof-of-principle demonstration experiment, AWAKE, is proposed using 400 GeV proton bunches from the SPS. Detailed studies on the identification of the best site for the installation of the AWAKE facility resulted in proposing the CNGS facility as best location. Design and integration layouts covering the beam line, the experimental area and all interfaces and services will be shown. Among other issues, radiation protection, safety and civil engineering constraints will be raised.

TUPEA055

Quasistatic Field Influence on Bunches Focusing by Wakefields in the Plasma-dielectric Waveguide

plasma, wakefield, focusing, acceleration

1256

R.R. Kniaziev
KhNU, Kharkov, Ukraine
G.V. Sotnikov
NSC/KIPT, Kharkov, Ukraine

Funding: The research is supported in part by Global Initiatives for Proliferation Prevention (GIPP) program, project ANL-T2-247-UA (STCU Agreement P522).
Acceleration of charged particles by wakefields, excited by a drive electron bunch in the dielectric waveguide, is a perspective method in accelerator physics. We have previously proposed using plasma, filling the drift channel of the dielectric structure (DS), for focusing of the accelerated bunch*. The analytical expressions, obtained for the components of the electromagnetic field, considered only the propagating wake field, and did not consider quasi-static fields of electron bunches that are important for calculating bunches dynamics. In this paper we report the result of numerical calculations of the influence of quasistatic field of bunches on focusing by wake fields in the plasma-dielectric accelerator. We refine analytical expressions for the electromagnetic field by adding components of bunch quasi-static fields and show the correlation of total force and their quasi-static components.
* R.R. Knyazev, G.V. Sotnikov. Focusing of accelerated particles by wakefields of a drive bunch in a plasma-dielectric waveguide. Proc. of IPAC2012, New Orleans, Louisiana, USA, paper weppp003.pdf

TUPEA056

Concept of Dielectric Wakefield Accelerator Driven by a Long Sequence of Electron Bunches

wakefield, acceleration, injection, resonance

1259

I.N. Onishchenko, V. Kiselev, A. Linnik, G.V. Sotnikov
NSC/KIPT, Kharkov, Ukraine

Funding: This study is supported by Global Initiatives for Proliferation Prevention (GIPP) program, project ANL-T2-247-UA (STCU Agreement P522)
The scheme of a two-beam accelerator type is considered that is based on wakefield excitation in rectangular dielectric resonator by a sequence of electron bunches with the aim to enhance wakefield intensity due to multi-bunch coherent excitation, multi-mode summation, and wakefield accumulation in resonator. The sequence of bunches can be divided into exciting and accelerated parts in any proportion by means at the proper detuning of bunch repetition frequency relative to the frequency of principle eigen mode of the resonator. A train of 6000 electron bunches, each of energy 4.5МeV, charge 0.16nC, duration 60psec, diameter 1.0cm, and angular spread 0.05 mrad is produced with the linear resonant accelerator. Bunch repetition frequency is 2805 MHz and can be varied within 2MHz by changing master oscillator frequency. Bunches are injected into copper rectangular waveguide of cross-section 8.5x18.0cm² and length 75cm along wide sides of which Teflon plates are placed. The plate thickness is chosen 1.67cm so that the frequency of excited eigen mode coincides with bunch repetition frequency.

TUPEA057

Optimization of Rectangular Dielectric Structures for the Planned Wakefield Acceleration Experiments in KIPT

wakefield, accelerating-gradient, acceleration, vacuum

1262

G.V. Sotnikov, K.V. Galaydych, V. Kiselev, P.I. Markov, I.N. Onishchenko
NSC/KIPT, Kharkov, Ukraine

Funding: This study is supported by Global Initiatives for Proliferation Prevention (GIPP) program, project ANL-T2-247-UA (STCU Agreement P522).
We, at the Kharkov Institute of Physics and Technology, planned experimental test of the basic principles of the multi-bunch multi-mode wakefield accelerator. For this purpose we carried out a series of calculations of wakefield excitation and dynamics of the drive and witness bunches in rectangular structures with a dielectric substrate. For optimization two rectangular vacuum waveguides of R32 (72.14mm x 34.04mm) and R26 (86.36mm x 43.18mm) which were filled with the dielectric covering two any opposite metal walls of a waveguide were chosen. As possible dielectric Alumina, Cordierite, or Teflon were tested. It was supposed that the structure will be energized by sequence of electron bunches (bunch repetition frequency is 2.805 GHz), having energy of 4.5 MeV. As the candidate for operating mode LSM-wave or LSE-wave, with frequency to equal the bunch repetition frequency or its doubled frequency were tested. The gradient of an accelerating field, small transverse deflection (or divergence) of drive and witness bunches were the main criteria of optimization. As a result of optimization we propose some dielectric structures for future wakefield experiments in KIPT.

TUPEA058

The Conceptual Design of CLARA, A Novel FEL Test Facility for Ultrashort Pulse Generation

FEL, laser, photon, linac

1265

J.A. Clarke, D. Angal-Kalinin, R.K. Buckley, S.R. Buckley, P.A. Corlett, L.S. Cowie, D.J. Dunning, B.D. Fell, P. Goudket, A.R. Goulden, S.P. Jamison, J.K. Jones, A. Kalinin, B.P.M. Liggins, L. Ma, K.B. Marinov, P.A. McIntosh, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, A.J. Moss, B.D. Muratori, H.L. Owen, R.N.C. Santer, Y.M. Saveliev, R.J. Smith, S.L. Smith, E.W. Snedden, M. Surman, T.T. Thakker, N. Thompson, R. Valizadeh, A.E. Wheelhouse, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R. Appleby, M. Serluca, G.X. Xia
UMAN, Manchester, United Kingdom
R.J. Barlow, A.M. Kolano
University of Huddersfield, Huddersfield, United Kingdom
R. Bartolini, I.P.S. Martin
Diamond, Oxfordshire, United Kingdom
N. Bliss, R.J. Cash, G. Cox, G.P. Diakun, A. Gallagher, D.M.P. Holland, B.G. Martlew, M.D. Roper
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
S.T. Boogert
Royal Holloway, University of London, Surrey, United Kingdom
G. Burt
Lancaster University, Lancaster, United Kingdom
L.T. Campbell, B.W.J. MᶜNeil
USTRAT/SUPA, Glasgow, United Kingdom
S. Chattopadhyay
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A. Lyapin
JAI, Egham, Surrey, United Kingdom
D. Newton, A. Wolski
The University of Liverpool, Liverpool, United Kingdom
V.V. Paramonov
RAS/INR, Moscow, Russia

The conceptual design of CLARA, a novel FEL test facility focussed on the generation of ultrashort photon pulses with extreme levels of stability and synchronisation is described. The ultimate aim of CLARA is to experimentally demonstrate, for the first time, that sub-coherence length pulse generation with FELs is viable. The results will translate directly to existing and future X-Ray FELs, enabling them to generate attosecond pulses, thereby extending the science capabilities of these intense light sources. This paper will describe the design of CLARA, pointing out the flexible features that will be incorporated to allow multiple novel FEL schemes to be proven.

TUPEA060

Jitter Tolerance for CLARA

linac, laser, cathode, FEL

1271

B.P.M. Liggins, J.K. Jones, J.W. McKenzie, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
J.K. Jones, B.P.M. Liggins, J.W. McKenzie, P.H. Williams
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: Science & Technology Facilities Council
CLARA (Compact Linear Accelerator for Research and Applications) at Daresbury Laboratory will be a test-bed for novel FEL configurations. CLARA will consist of an RF photoinjector, S-band acceleration and transport to 250 MeV including X-band linearisation and magnetic bunch compression. Ensuring stability of the VUV radiation pulses is a key aim of the project. To this end, we investigate in detail the jitter tolerance of the machine. This will ultimately determine the pulse stability.

TUPEA061

High-Brightness SASE Studies for the CLARA FEL

undulator, FEL, radiation, simulation

1274

R.N.C. Santer, N. Thompson
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The Compact Linear Accelerator for Research and Applications (CLARA) is a proposed 250 MeV FEL test facility to be constructed at STFC Daresbury Laboratory in the UK [1]. This paper presents study of a scheme for the temporal and spectral stabilisation of the SASE output. A feasibility study for the operation of the FEL in a novel High-Brightness SASE mode is presented. Electron beam delays are introduced between undulator sections to disrupt the localised collective FEL process, increase the radiation coherence length and reduce the rms bandwidth. This may extend the range of electron bunch lengths appropriate for the generation of temporally coherent single spike SASE FEL pulses.

TUPEA064

A Proposed Plasma Accelerator Research Station at CLARA Facility

plasma, wakefield, simulation, acceleration

1280

G.X. Xia, K. Hanahoe
UMAN, Manchester, United Kingdom
D. Angal-Kalinin, J.A. Clarke, J.K. Jones, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
J.D.A. Smith
TXUK, Warrington, United Kingdom

We propose a Plasma Accelerator Research Station (PARS) based at proposed FEL test facility Compact Linear Accelerator for Research and Applications (CLARA) at Daresbury lab. The idea is to use the relativistic electron beam from CLARA, to investigate some key issues in electron beam transport and in the electron beam driven plasma wakefield acceleration, e.g. the two bunch acceleration for CLARA beam energy doubling, high transformer ratio, long bunch self-modulation and the related beam instabilities. This paper discusses the feasibility studies of electron beam parameters to meet the requirements for beam driven wakefield acceleration and the possible experiments which can be conducted at PARS beam line.

TUPEA065

Design of a Photonic Crystal Accelerator for Basic Radiation Biology

laser, vacuum, acceleration, simulation

1283

A. Aimidula, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
A. Aimidula, C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
K. Koyama, Y. Matsumura
University of Tokyo, Tokyo, Japan
T. Natsui, M.Y. Yoshida
KEK, Ibaraki, Japan
M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
G.X. Xia
UMAN, Manchester, United Kingdom

Funding: This work is supported by the EU under Grant Agreement 289485, the STFC Cockcroft Institute Core Grant No. ST/G008248/1 and KAKENHI, Grant-in-Aid for Scientific Research (C) 24510120.
The application of photonic crystals to realize an on-chip electron beam source for fundamental radiation biology is highly interesting for a number of applications. The unique combination of nanometer beam size and attosecond-short pulses has a very promising potential for use in microscopic and ultra-fast analyses of damage and repair of radiation-irradiated DNA and chromosomes. Simulations studies indicate an output electron beam energy, beam intensity and device size of the order of MeVs, fCs and a few cm, respectively. In this contribution, first results from numerical studies into the design of such compact accelerator structure are presented. The dimensions of a novel dual grating-based acceleration structure are shown together with the estimated laser parameters. Finally, a system consisting of an electron injector and multi-stage accelerating structures is proposed, which corresponds to a miniaturized optical linear accelerator.

TUPEA066

Metamaterial-based Accelerating, Bending and Focusing Structures

focusing, quadrupole, vacuum, resonance

1286

I. McGregor
The University of Liverpool, Liverpool, United Kingdom
K.M. Hock
Cockcroft Institute, Warrington, Cheshire, United Kingdom

We report on the progress of our research into metamaterial-based accelerating, bending and focusing structures at the Cockcroft Institute. The effort during the last year has been directed towards designing and investigating practical RF structures that are suitable for industrial and medical applications. We have shown that, by introducing structures based on metamaterial resonators, RF accelerating structures can be made more compact and higher gradient. This year, we will concentrate on focusing and bending structures.

TUPEA072

Toward a Dielectric-Wakefield Energy Doubler at the Fermilab's Advanced Superconducting Test Accelerator

emittance, acceleration, simulation, wakefield

1295

F. Lemery, D. Mihalcea, P. Piot, C.R. Prokop
Northern Illinois University, DeKalb, Illinois, USA
P. Piot, Y.-E. Sun
Fermilab, Batavia, USA
P. Stoltz
Tech-X, Boulder, Colorado, USA

Funding: This work is supported by DTRA contract HDTRA1-10-1-0051 and by the U.S. DOE contracts DE-FG02-08ER41532 and DE-AC02-07CH11359.
The Advanced Superconducting Test Accelerator (ASTA), presently under construction at Fermilab, will produce high-charge (~<3 nC) electron bunches with energies ranging from 50 to eventually 750 MeV. The facility is based on a superconducting linac capable of producing up to 3000 bunches in 1-ms macropulses repeated at 5 Hz. In this paper we explore the use of a short dielectric-lined-waveguide (DLW) linac to significantly increase the bunch energy. The method consists in (1) using advanced phase space manipulation techniques to shape the beam distribution and enhance the transformer ratio, and (2) optimize the generation and acceleration of a low-charge witness bunches. Start-to-end simulations of the proposed concept are presented. This DLW module could also be used to test some aspects of a recently proposed concept for a multiuser short-wavelength free-electron laser utilizing a series of DLW linacs*.
* C. Jing et al., “A Compact Soft X-ray Free-Electron Laser Facility based on a Dielectric Wakefield Accelerator”, Advanced Photon Source LS Note LS-332, Argonne National Laboratory (2012).

TUPEA073

Performances of VORPAL-GPU Slab-symmetric DLW

simulation, wakefield, factory, dumping

1298

F. Lemery, K. Duffin, N. Karonis, D. Mihalcea, P. Piot, J. Winans
Northern Illinois University, DeKalb, Illinois, USA
P.J. Mullowney, P. Stoltz
Tech-X, Boulder, Colorado, USA
P. Piot
Fermilab, Batavia, USA

Funding: HDTRA1-10-1-0051, DOE(Grant No will be specified later)
GPU-based computing has gained popularity in recent years due to its growing software support and greater processing capabilities than its CPU counterpart. GPU computing was recently added in the finite-difference time-domain program VORPAL. In this paper we carry electromagnetic simulations and optimization of a flat beam passing through a slab-symmetric dielectric-lined waveguide (DLW). We use this simulation model to explore the scaling of the GPU version of VORPAL on a new TOP1000-grade hybrid GPU/CPU computer cluster available at Northern Illinois University.

TUPEA074

Protection of VUV FEL Mirrors using Soft Orbit Bump at Duke FEL/HIGS facility

FEL, radiation, wiggler, dipole

1301

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

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

TUPEA075

Passively Driving X-band Structures to Achieve Higher Beam Energies

linac, impedance, laser, gun

1304

S. Biedron, S.V. Milton, N. Sipahi, T. Sipahi
CSU, Fort Collins, Colorado, USA

Particle accelerators at X-band frequencies have gradients of around 100 MV/m. This technology permits more compact accelerators. One of our aims at the Colorado State University Accelerator Laboratory is to adapt this technology to our L-band (1.3 GHz) accelerator system to increase our overall beam energy; however, we would like to do this in a passive manner, i.e. one that does not require investment in an expensive, custom, high-power klystron system. In this paper we explore using the beam from our L-band 6 MeV photoinjector to power an x-band structure tuned to the 9th harmonic of our L-band system, 11.7 GHz. Electron bunches will be generated at a repetition rate of 81.25 MHz and passed through a high shunt impedance x-band accelerating structure where they will resonantly excite the fundamental field. We will optimize the system to create the highest accelerating potential within this structure. Once the peak gradient is achieved we will send a single electron bunch through the system at a phase that places it on the crest of the X-band accelerating wave thereby increasing the electron bunch energy by some amount without need for additional external power sources.

TUPEA079

Experimental Search For Acceleration in the Micro-accelerator Platform

laser, acceleration, vacuum, coupling

1307

J.C. McNeur, K.S. Hazra, B. Matthews, E.B. Sozer, G. Travish
UCLA, Los Angeles, USA
R.J. England, B. Montazeri, K. Soong, Z. Wu
SLAC, Menlo Park, California, USA
E.A. Peralta
Stanford University, Stanford, California, USA
R.B. Yoder
Goucher College, Baltimore, USA

The results of recent experimental efforts to observe acceleration in the Micro-Accelerator Platform (MAP) are detailed. The MAP is a slab-symmetric dielectric laser accelerator that when side illuminated by an optical laser, accelerates electrons via a standing wave resonance. This structure has been placed in the beamline at the NLCTA experimental hall at SLAC. A 60 MeV electron beam traverses the MAP when it is illuminated by a laser and, using a camera placed around a spectrometer bend magnet, signs of acceleration in the energy spectrum of the beam are searched for. The details of this search, as well as simulations that motivate the search, are elaborated on below.

TUPEA080

Numerical Modeling and Experimental Data Analysis for Dielectric Laser Accelerators

laser, acceleration, vacuum, GUI

1310

E.B. Sozer, K.S. Hazra, J.C. McNeur, G. Travish
UCLA, Los Angeles, USA
R.J. England, K. Soong
SLAC, Menlo Park, California, USA
E.A. Peralta
Stanford University, Stanford, California, USA
R.B. Yoder
Goucher College, Baltimore, USA

Funding: Work supported by a grant for the US Defense Threat Reduction Agency (DTRA).
Work on Dielectric Laser Accelerators (DLAs) has been ongoing for the past decade. These devices come in a variety of configurations but share the use of lasers as power sources and dielectrics as the primary building material. While these devices have many of the same characteristics and dynamics as conventional accelerating structures, they operate in a dramatically different regime. One version of these DLAs is the Micro Accelerator Platform (MAP): a slab-symmetric device operated with a standing wave (Pi-mode) and powered by a transversely coupled laser. The coupler is essentially a transmissive diffraction grating and therefore reinforced the desired mode. The remainder of the structure is composed of two Distributed Bragg Reflectors (DBRs) which serve to form a resonant cavity in an evacuated bounded by the reflectors. The MAP has now undergone experimental testing at SLAC’s E-163. As with many advanced accelerators, identifying the best data analysis approach demands extensive numerical modelling of the anticipated beam parameters and development of data visualization tools. We present the latest numerical results and data analysis tools developed for dielectric laser acceleration experiments with MAP.

TUPEA086

Femtosecond Electron Beam and X-ray Beams at the Linac Coherent Light Source

FEL, linac, emittance, laser

1316

Y.T. Ding, A. Brachmann, F.-J. Decker, R.C. Field, J.C. Frisch, Z. Huang, R.H. Iverson, H. Loos, H.-D. Nuhn, D.F. Ratner, J.L. Turner, J.J. Welch, J. Wu, F. Zhou
SLAC, Menlo Park, California, USA
P. Emma
LBNL, Berkeley, California, USA

Generation of ultrashort x-ray pulses (femtoseconds to attoseconds) is attracting much attention within the x-ray FEL user community. At the Linac Coherent Light Source (LCLS), we have successfully delivered femtosecond x-ray pulses to the users with two operating modes – low-charge (20-40pC) scheme and emittance spoiling foil method. Diagnostics on the femtosecond beams is also a challenging topic and good progresses have been made at LCLS. In this paper we report the experimental studies on the two femtosecond operation schemes, the x-ray performance and also the diagnostic progress.

TUPEA087

Experiment on Multipactor Suppression in Dielectric-loaded Accelerating Structures with a Solenoid Field

multipactoring, solenoid, simulation, plasma

1319

C.-J. Jing, S.P. Antipov, A. Kanareykin, P. Schoessow
Euclid TechLabs, LLC, Solon, Ohio, USA
C. Chang, L. Ge, L. Xiao
SLAC, Menlo Park, California, USA
M.E. Conde, W. Gai, R. Konecny, J.G. Power
ANL, Argonne, USA
S.H. Gold
NRL, Washington, DC, USA

Funding: US DoE SBIR Phase I project under contract #DE-SC0007629
Efforts by numerous institutions have been ongoing over the past decade to develop a Dielectric-Loaded Accelerating (DLA) structure capable of supporting high gradient acceleration when driven by an external rf source. Multipactor is the major issue limiting the gradient that was revealed in earlier experiments. A theoretical model predicts that the strength of solenoid field within an optimal range applied to DLA structures may completely block the multipactor. To demonstrate this approach, two DLA test structures have been built and the first high power test will be conducted in December 2012. The results will be reported.

TUPEA089

Modeling and Experimental Update on Quasi-phase Matched Direct Laser Electron Acceleration In Density-modulated Plasma Waveguides

plasma, laser, simulation, target

1325

M.W. Lin, D.R. Abercrombie, I. Jovanovic, A. Rakhman
Penn State University, University Park, Pennsylvania, USA

Funding: This work has been supported by the Defense Threat Reduction Agency through Contract HDTRA1-11-1-0009.
Direct laser acceleration (DLA) of electrons using the axial electric field of a radially polarized, guided intense laser pulse has the potential to lead to compact laser-driven accelerators* for security and medical applications. A density-modulated plasma waveguide could be applied to extend the laser beam propagation distance and to achieve quasi-phase matching (QPM) between laser and electron pulses for efficient DLA**. We conduct numerical simulations to design the appropriate plasma structure of the waveguides and investigate the properties of accelerated electron beams. An all-optical method, based on the igniter-heater scheme for plasma waveguide fabrication, is experimentally implemented to machine the density-modulated plasma waveguides with low-Z gas targets. A novel angle-multiplexed diagnostic technique has been developed to extract the polarization state and temporal characteristics of a radially polarized femtosecond laser pulse using spatial-spectral interferometry***. The goal of our experiments is to characterize the propagation of femtosecond radially polarized pulses in plasma waveguides.
* P. Serafim, et al., IEEE Trans. Plasma Sci. 28, 1155 (2000).
** M. -W. Lin and I. Jovanovic, Phys. Plasmas 19, 113104 (2012).
***P. Bowlan, et al., Opt. Exp. 14, 11892 (2006)

TUPFI002

Electron Cloud and Scrubbing Studies for the LHC

injection, emittance, dipole, luminosity

1331

G. Iadarola
Naples University Federico II, Science and Technology Pole, Napoli, Italy
G. Arduini, V. Baglin, H. Bartosik, C.O. Domínguez, J. Esteban Müller, G. Iadarola, G. Rumolo, E.N. Shaposhnikova, L.J. Tavian, F. Zimmermann
CERN, Geneva, Switzerland
C.O. Domínguez
EPFL, Lausanne, Switzerland
G.H.I. Maury Cuna
CINVESTAV, Mexico City, Mexico

Electron cloud build-up resulting from beam-induced multipacting is one of the major limitations for the operation of the LHC with beams with close bunch spacing. Electron clouds induce unwanted pressure rise, heat loads on the beam screens of the superconducting magnets and beam instabilities. Operation with bunch spacing of 50 ns in 2011 and 2012 has required decreasing the Secondary Electron Yield of the beam screens below the multipacting threshold for beams with this bunch spacing. This was achieved by continuous electron bombardment induced by operating the machine with high intensity beams with 50 and 25 ns spacing during dedicated periods at injection energy (450 GeV) and at top energy (3.5 and 4 TeV). The evolution of the Secondary Electron Yield during these periods, at different sections of the machine, can be estimated by pressure, heat load and by bunch-by-bunch RF stable phase measurements. The experimental information on the scrubbing process will be discussed and a possible “scrubbing strategy” to allow the operation with 50ns and 25ns beams after the Long Shutdown in 2013-2014 will be presented.

TUPFI005

Synchrotron-Radiation Photon Distribution for Highest Energy Circular Colliders

photon, scattering, radiation, vacuum

1340

G.H.I. Maury Cuna
CINVESTAV, Mérida, Mexico
G. Dugan, D. Sagan
CLASSE, Ithaca, New York, USA
F. Zimmermann
CERN, Geneva, Switzerland

Funding: Acknowledgements to CINVESTAV, CERN and EPLANET project.
At high energies, beam-induced synchrotron radiation is an important source of heating, beam-related vacuum pressure increase, and primary photoelectrons, which can give rise to an electron cloud. The photon distribution along the beam pipe wall is a key input to codes such as ECLOUD and PyECLOUD, which model the electron cloud build-up. For future high-energy colliders, like TLEP or SHE-LHC, photon stops and antechambers are considered in order to facilitate cooling and vacuum pressure control. We use the Synrad3D code developed at Cornell to simulate the photon distribution for the LHC.

TUPFI045

Electron-cloud Maps for LHC Scrubbing Optimization

injection, simulation, dipole, beam-losses

1451

C.O. Domínguez, F. Zimmermann
CERN, Geneva, Switzerland

Electron-cloud maps as alternative to detailed build-up simulations have already been applied in the past for a few accelerators, e.g. RHIC and the LHC at 7 TeV. We here report a first application of maps to optimize the "beam scrubbing" of the LHC arcs at injection energy: Maps are used to efficiently determine the optimum bunch filling pattern which maximizes the electron flux on the chamber wall, while respecting constraints on the central cloud density to ensure beam stability. In addition, new features have been explored, e.g. by introducing thresholds which divide regions where either linear maps or cubic maps best describe the build-up and the decay of an electron cloud. In the near future we plan to extend the map formalism to individual slices in a dipole file in order to represent the vertical "stripes".

TUPFI053

Transient Beam Loading Effects in Gas-filled RF Cavities for a Muon Collider

cavity, plasma, ion, beam-loading

1463

M. Chung, A.V. Tollestrup, K. Yonehara
Fermilab, Batavia, USA
B.T. Freemire
IIT, Chicago, Illinois, USA

Funding: Research supported by the U.S. Department of Energy.
A gas-filled RF cavity can be an effective solution for the development of a compact muon ionization cooling channel. One possible problem expected in this type of cavity is the dissipation of significant RF power through the beam-induced plasmas accumulated inside the cavity (plasma loading). In addition, for the higher muon beam intensity, the effects of the beam itself on the cavity fields in the accelerating mode are non-negligible (beam loading). These beam-cavity interactions induce a transient phase which may be very harmful to the beam quality. In this study, we estimate the transient voltage in a gas-filled RF cavity with both the plasma and conventional beam loading and discuss their compensation methods.

TUPFI058

Simulation of Beam-induced Gas Plasma in High Gradient RF Field for Muon Colliders

ion, simulation, plasma, electromagnetic-fields

1478

K. Yonehara, M. Chung, A.V. Tollestrup
Fermilab, Batavia, USA
B.T. Freemire
IIT, Chicago, Illinois, USA
R.P. Johnson, T.J. Roberts
Muons. Inc., USA
R.D. Ryne
LBNL, Berkeley, California, USA
V. Samulyak
BNL, Upton, Long Island, New York, USA
K. Yu
SBU, Stony Brook, USA

There is a strong limit of available RF gradient in a vacuum RF cavity under magnetic fields because the magnetic field enhances a dark current density due to electron focusing and increases probability of an electric breakdown. This limits the cooling performance. A dense hydrogen gas filled RF cavity can break this limit because the gas acts as a buffer of dark current. However, RF power loading due to a beam-induced plasma in a dense gas filled RF cavity (plasma loading effect) is crucial to design the practical cavity. Experiment shows that the plasma loading can be mitigated in denser hydrogen gas and by doping a small amount of electronegative gas in the cavity. A complicate plasma chemical reaction should be dominated in such a dense hydrogen gas condition. A beam-induced plasma is simulated by taking into account the plasma chemistry to reproduce the condition by using the supercomputer at LBNL. We will also investigate the space charge effect in a dense gas in this effort.

TUPFI059

Summary of Dense Hydrogen Gas Filled RF Cavity Tests for Muon Acceleration

proton, plasma, ion, photon

1481

K. Yonehara, M. Chung, M.R. Jana, M.A. Leonova, A. Moretti, A.V. Tollestrup
Fermilab, Batavia, USA
B.T. Freemire, P.M. Hanlet, Y. Torun
IIT, Chicago, Illinois, USA
R.P. Johnson
Muons. Inc., USA

Dense hydrogen gas filled RF cavity has a great potential to accelerate a large phase space muon beam in a strong magnetic field. The concept of novel RF cavity has been demonstrated by using an intense proton beam at Fermilab. The experimental result was agreed extremely well with the conventional dilute plasma physic. Based on the model, the beam-induced plasma in the gas filled RF cavity could be controlled by adding a small amount of electronegative gas in dense hydrogen gas. Overview of these experiments will be shown in this presentation.

TUPFI064

Beam Induced Plasma Dynamics in a High Pressure Gas-Filled RF Test Cell for use in a Muon Cooling Channel

ion, cavity, plasma, proton

1496

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

Filling an RF cavity with a high pressure gas prevents breakdown when the cavity is place in a multi-Tesla external magnetic field. The choice of hydrogen gas provides the additional benefit of cooling a beam of muons. A beam of particles traversing the cavity, be it muons or protons, ionizes the gas, creating an electron-ion plasma which absorbs energy from the cavity. The ionization rate can be calculated from a beam intensity measurement. Energy loss measurements indicate the loading per RF cycle per electron-ion pair range from 10^-18 to 10^-16 Joules in pure hydrogen, and 10^-20 to 10^-18 Joules when hydrogen is doped with dry air. The addition of an electronegative gas (oxygen) has been observed to reduce the lifetime of ionization electrons in the cavity to below 1 nanosecond. Additionally, the recombination rate of electrons and hydrogen ions has been measured to be on the order of 10^-6 cubic centimeters per second. The recombination mechanism and hydrogen ion species, along with the three-body attachment process of electrons to oxygen, will be discussed.

TUPFI077

Commissioning Progress of the RHIC Electron Lenses

solenoid, proton, lattice, controls

1526

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

Funding: Work supported by U.S. DOE under contract No DE-AC02-98CH10886 with the U.S. Department of Energy.
In polarized proton operation, the RHIC performance is limited by the head-on beam-beam effect. To overcome these limitations two electron lenses were installed and are under commissioning. One lens uses a newly manufactured superconducting solenoid, in the other lens the spare superconducting solenoid of the BNL Electron Beam Ion Source is installed to allow for propagation of the electron beam. (This spare magnet will be replaced by the same type of superconducting magnet that is also used in the other lens during the 2013 shut-down.) We give an overview of the commissioning configuration of both lenses, and report on first results in commissioning the hardware and electron beam. We also report on lattice modifications needed to adjust the phase advance between the beam-beam interactions and the electron lenses, as well as upgrades to the proton instrumentation for the commissioning.

TUPFI081

Progress with Coherent Electron Cooling Proof-Of-Principle Experiment

cavity, gun, ion, undulator

1535

I. Pinayev, S.A. Belomestnykh, I. Ben-Zvi, K.A. Brown, J.C. Brutus, L. DeSanto, A. Elizarov, C. Folz, D.M. Gassner, Y. Hao, R.L. Hulsart, Y.C. Jing, D. Kayran, R.F. Lambiase, V. Litvinenko, G.J. Mahler, M. Mapes, W. Meng, R.J. Michnoff, T.A. Miller, M.G. Minty, P. Orfin, A. Pendzick, F. Randazzo, T. Rao, T. Roser, J. Sandberg, B. Sheehy, J. Skaritka, K.S. Smith, L. Snydstrup, R. Than, R.J. Todd, J.E. Tuozzolo, G. Wang, D. Weiss, M. Wilinski, W. Xu, A. Zaltsman
BNL, Upton, Long Island, New York, USA
G.I. Bell, J.R. Cary, K. Paul, B.T. Schwartz, S.D. Webb
Tech-X, Boulder, Colorado, USA
C.H. Boulware, T.L. Grimm, R. Jecks, N. Miller
Niowave, Inc., Lansing, Michigan, USA
M.A. Kholopov, P. Vobly
BINP SB RAS, Novosibirsk, Russia
M. Poelker
JLAB, Newport News, Virginia, USA

We conduct proof-of-the-principle experiment of coherent electron cooling (CEC), which has a potential to significantly boost luminosity of high-energy, high-intensity hadron colliders. In this paper, we present the progress with experimental equipment including the first tests of the electron gun and the magnetic measurements of the wiggler prototype. We describe current design status as well as near future plans.

TUPME002

Design Integration at the International Linear Collider

lattice, positron, damping, civil-engineering

1559

B. List, L. Hagge, J. Kreutzkamp, N.J. Walker
DESY, Hamburg, Germany

In preparation for the Technical Design Report of the International Linear Collider, a comprehensive design of the accelerator has been compiled. DESY has contributed a systematic design integration approach, which helps to achieve a complete, correct and consistent design. We use the lattice as the leading element for design integration. Geometry information including 3D visualization models are derived from the lattice, and are used to ensure that the beamlines fit and suited for access and installation. The 3D models are also used as basis for tunnel and cavern layout. As detailed designs of components become available, the lattice is adjusted and the overall models are iterated. Lists of components are derived from the lattice and are used to generate a component bill of materials, which in turn serves as basis for cost estimation and installation planning. An integrated 3D model of the entire accelerator and all the civil construction elements helps to optimize the design for example with regard to space efficiency, ease of access for installation, and life safety. Setting up design integration in an early project stage results in a better design helps to reduce costs.

TUPME003

Simulations of the ILC Positron Source at Low Energies

positron, undulator, target, polarization

1562

A. Ushakov, V.S. Kovalenko, G.A. Moortgat-Pick
University of Hamburg, 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 Optimization", contract number 19XL7Ic4
The International Linear Collider (ILC) baseline design includes an undulator-based positron source. The accelerated electron beam will be used for the positron generation before it goes to the collision point. For the whole ILC energy range the source has to generate 1.5 positrons per electron. However, the efficiency of positron production goes down with decreasing electron drive beam energy. This effect can be compensated to some extend by the choice of undulator parameters and an optimized capture section. The simulation study considers for the range of electron beam energies down to low values of 120 GeV the feasibility to achieve the required positron yield. In particular, the optimum parameters for undulator and capture section are presented depending on the drive electron beam energy.

TUPME006

Simulation of Stress in Positron Targets for Future Linear Colliders

target, photon, positron, undulator

1571

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

Future linear collider projects require intense positron sources with yields of about 10¹⁴ positrons per second. The positron source for the ILC is based on a helical undulator passed by the accelerated electron beam to create an intense circularly polarized photon beam. The positron beam produced by these photons is longitudinally polarized. The intense photon beam causes rapid temperature increase in the target material resulting in periodic stress. The average and peak thermal and mechanical load are simulated. Implications due to long-term target irradiation are considered.

TUPME008

Beam Dynamics Studies for the Injection System of a High Luminosity Flavour Factory

linac, injection, positron, luminosity

1577

D. Pellegrini
CERN, Geneva, Switzerland
M.E. Biagini, S. Guiducci
INFN/LNF, Frascati (Roma), Italy

The requirements, in terms of average luminosity and lifetimes, of high luminosity e⁺e⁻ colliders such as the Flavor factories, pose stringent constraints to the design of the injection complex. For the SuperB B-factory project at Tor Vergata, Italy, a design was developed to deliver full energy bunches (4.2 GeV e^- and 6.7 GeV e+) to the main rings every 30 ms aiming at a high and nearly constant luminosity. The system included a polarized electron gun, a positron production system, linac sections, a Damping Ring (DR) and transfer lines connecting to the collider Main Rings (MR). After the decision, due to budget issues, to rescale the project to a lower energy (2.3 GeV/beam) for a tau/charm flavour factory, the same design principles have been applied. In this paper beam dynamics studies from the DR to the MR entrance is presented, including optimization of the transfer lines and of the bunch compressor. A start to end simulation shows that the beam quality satisfies theinjection requirements, even in the presence of energy errors and collective effects like CSR and wakefields.

TUPME010

High-intensity and Low-emittance Upgrade of 7-GeV Injector Linac towards SuperKEKB

positron, emittance, linac, laser

1583

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

After a decade of successful operation at KEKB a new electron/positron collider, SuperKEKB, is being constructed to commission within FY2014. It aims at a luminosity of 8 x 10³⁵ /s.cm², 40-times higher than that of KEKB, in order to study the flavor physics of elementary particles further, by mainly squeezing the beams at the collision point. The injector linac should provide high-intensity and low-emittance beams of 7-GeV electron and 4-GeV positron by newly installing a RF-gun, a flux concentrator, and a damping ring with careful emittance and energy management. It also have to perform simultaneous top-up injections into four storage rings by pulse-to-pulse beam modulations not to interfare between three facilities of SuperKEKB, Photon Factory and PF-AR. This paper describes the injector design decisions and present status of the construction.

TUPME013

Coherent Thomson Scattering using Beam Echo

laser, scattering, undulator, radiation

1592

K. Ohmi, S. Kamada
KEK, Ibaraki, Japan
H. Fares
Kanazawa University, Kanazawa, Japan

Longitudinal phase space of the beam is modulated by laser interacting in undulators. The beam can have higher frequency component using the beam echo than than the laser as dicussed by G. Stupakov et al. The modulated beam has a potential to emit coherent radiation with the wave length. We evaluate coherent short wave length (~nm) and/or short pulse (attosec) light source using the beam echo in a low energy accelerator ~100MeV.

TUPME015

Proposal of Polarized Gamma-ray Source for ILC Based on CSR Inverse Compton Scattering

cavity, positron, scattering, laser

1598

M. Shimada, K. Yokoya
KEK, Ibaraki, Japan
R. Hajima
JAEA, Ibaraki-ken, Japan
M. Tecimer
University of Hawaii at Manoa, Honolulu, USA

The positron source of International Linear Collider (ILC) requires a circular polarized gamma-ray with a flux more than 10¹⁶ phs./s and a helical undulator-based gamma-ray source is proposed in the baseline design. Although the undulator scheme is technically feasible, it is not easy for a stand-alone operation because of the required electron energy, ~ 150GeV. In this paper, we propose an alternative method, the inverse Compton scattering with a high-power mid-infrared optical pulse generated from coherent synchrotron radiation (CSR). To achieve the high flux gamma-ray, CSR with a few MHz is stacked in a high-finesse optical cavity made of a photonic crystal. In the proposed scheme, a stand-alone operation is feasible because the electron energy is less than 10GeV.

TUPME018

Construction of New 90 MeV Injector Linac for the 1.2 GeV Booster Synchrotron at Tohoku University

linac, gun, synchrotron, quadrupole

1607

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

The Great East Japan Earthquake (March 11, 2011) has inflicted enormous damage on the accelerator facility of Research Center for Electron Photon Science, Tohoku University. A 300 MeV linac operated for 46 years as an accelerator for radioisotope production and also as an injector of the 1.2 GeV booster synchrotron for nuclear physics experiments. The accelerator will be rebuilt with all the recyclable components. New small linac is constructed as the injector for the booster synchrotron. The injector consists of thermionic rf-gun, two 3m-long accelerating structures, and transport line to the synchrotron. The maximum energy of injector is 90 MeV with beam loading. The detail of the injector linac is introduced in this conference.

TUPME025

Calculation of the Equilibrium Parameters for the Compact Ring of TTX

emittance, photon, scattering, storage-ring

1625

H.S. Xu, W.-H. Huang, C.-X. Tang
TUB, Beijing, People's Republic of China
S.-Y. Lee
IUCEEM, Bloomington, Indiana, USA

Intra-Beam Scattering (IBS) can cause emittance growth in high intensity low energy beams. We study its effect on the compact low energy electron storage ring, proposed for Tsinghua Thomson Scattering X-ray source (TTX). For a single bunch with peak current at about 17A and re-entrant type normal conducting RF cavity with peak voltage at 15kV, the equilibrium horizontal and vertical emittances are 2.9 and 0.3 μm, and the rms momentum spread and bunch length are about 0.2%, and 23ps. In this paper, we report the methods and results of the IBS calculation.

TUPME027

Advanced Studies on New Generation of Electron-positron Accelerators and Colliders for Fundamental and Applied Researches

laser, FEL, radiation, gun

1631

A. Dudarev, N. Balalykin, U.A. Budagov, V. Kobets, M.V. Lyablin, B.M. Sabirov, G. Shirkov, E. Syresin, G.V. Trubnikov
JINR, Dubna, Moscow Region, Russia

JINR actively leads the R&D works in particle accelerator physics and engineering, construction of the free electron laser with the aim to prepare proposals for the project of JINR participation in international collaboration on construction of the future Linear Collider (CLIC/ILC). JINR scientists and engineers study in free electron laser physics, development and construction of systems applied for formation and diagnostics of ultra short dense bunches in the linear electron accelerators. JINR physicists also take part in several fields of activity in ILC: works on photo injector prototype, participation in design and construction of cryomodules, laser metrology, and possible ILC location near Dubna.

TUPME028

RF Orbit Separation for CPT-Test Experiment at VEPP-4M

positron, betatron, closed-orbit, beam-beam-effects

1634

V.E. Blinov, E.A. Bekhtenev, G.V. Karpov, V.A. Kiselev, S.A. Krutikhin, G.Y. Kurkin, E.B. Levichev, O.I. Meshkov, S.I. Mishnev, V.V. Neyfeld, S.A. Nikitin, I.B. Nikolaev, D.N. Shatilov, G.M. Tumaikin
BINP SB RAS, Novosibirsk, Russia
A.P. Chabanov, O.P. Gordeev, A.I. Mickailov
Budker INP & NSU, Novosibirsk, Russia

Funding: This work was supported by the Ministry of Education and Science of the Russian federation and the Russian Foundation for Basis Research (grant 11-02-01422-a)
In a special program of experiments which is under development in a background regime at the VEPP-4M storage ring we set an aim to realize a potential possibility to make the CPT invariance test with the accuracy better than 10^-8. The test will be based on a precise comparison of the spin precession frequencies of simultaneously stored electrons and positrons. To exclude the presence of static electric fields increasing a systematic error we have developed and tested a special RF system driven at the half revolution frequency to subsitute for the electrostatic orbit separation system. The latter is needed for the electron and positron orbit separation at the parasitic interaction point where the beam-beam effects drastically cut the beam currents.

TUPME029

VEPP-4: Application Beyond the High Energy Physics

positron, collider, radiation, target

1637

O.I. Meshkov
BINP SB RAS, Novosibirsk, Russia

The current status of VEPP-4M electron-positron collider has been described. During fall of 2011 the accelerator was shut down for planned reconstruction of KEDR detector. The next long run of the collider will be dedicated to the experiments at high energy physics within area of 2-5 GeV. Nevertheless, the set of experiments at booster VEPP-3 were continued. VEPP-3 was operated as an SR source, the experiment with internal target was performed and electron/positron scattering at proton was studied. The short runs of VEPP-4M were used as for commissioning of the new “warm” 3T wiggler as for experiments with an extracted electron beam dedicated for testing of different high energy physics detectors. The experiment of comparing of anomalous magnetic moment of electron and positron is con-tinued at VEPP-4M. The system of RF beam shifting is installed at a straight section of the accelerator. It is applied for elimination of parasitic interaction points of electron and positron beams. The first experiments with this system are described. KEDR detector reconstruction should be finished at autumn of 2013. The future experiments with KEDR detector are discussed.

TUPME031

Considerations for a Higgs Facility Based on Laser Wakefield Acceleration

plasma, laser, luminosity, collider

1643

S. Hillenbrand, A.-S. Müller
KIT, Karlsruhe, Germany
R.W. Aßmann, S. Hillenbrand, D. Schulte
CERN, Geneva, Switzerland

Laser Wakefield Accelerators have seen tremendous progress over the last decades. It is hoped that they will allow to significantly reduce the size and cost of a future liner collider. Based on scaling laws, laser-driven plasma accelerators are investigated as drivers for smaller scale facilities capable of producing Z and Higgs bosons.

TUPME052

Sub-harmonic Buncher Design for the CLIC Drive Beam Injector

coupling, beam-loading, linear-collider, collider

1685

H. Shaker, S. Döbert, R. Leuxe, S. Sanaye Hajari
CERN, Geneva, Switzerland
L. Dassa
Università di Brescia, Brescia, Italy
S. Sanaye Hajari, H. Shaker
IPM, Tehran, Iran

The CLIC (Compact LInear Collider) is based on two beam concept where a high current drive beam provides the energy needed for acceleration of the main beam. The CLIC drive beam accelerator starts with a high current injector using a sophisticated sub-harmonic bunching system. This paper will focus on the design of the Sub Harmonic Bunchers (SHBs) the first RF components of the injector. A backward traveling wave structure has been optimized for this task. It will be shown also how to avoid asymmetrical fields inside the coupler cells and how to compensate beam loading by changing the phase velocity in comparison to the beam velocity.

TUPME053

General Beam Loading Compensation in a Traveling Wave Structure

beam-loading, bunching, linac, storage-ring

1688

H. Shaker, S. Döbert
CERN, Geneva, Switzerland
H. Shaker
IPM, Tehran, Iran

The well-known beam loading in a traveling wave structure is in fact a resistive beam loading which bunches travel on the crest. This type of beam loading could be compensated by increasing RF feed power. But generally, bunches could travel on each phase. General beam loading compensation is well-known for a single cell cavity and it is done by changing the RF feed power and detuning the structure together. In this paper, the concept of detuning for a TW structure will be shown and the evolution of fundamental mode beam-induced field will be derived and finally, it will be shown how to compensate beam loading by changing the phase velocity in comparison to the beam velocity.

TUPME055

Strawman Optics Design for the CERN LHeC ERL Test Facility

linac, optics, emittance, lattice

1694

A. Valloni, O.S. Brüning, R. Calaga, E. Jensen, M. Klein, R. Tomás, F. Zimmermann
CERN, Geneva, Switzerland
S.A. Bogacz, D. Douglas
JLAB, Newport News, Virginia, USA

In preparation for a future Large Hadron electron Collider (LHeC) at CERN, an ERL test facility is foreseen as a test bed for SRF development, cryogenics, and advanced beam instrumentation, as well as for studies of ERL-specific beam dynamics. The CERN ERL test facility would comprise two linacs, each consisting of 4 superconducting 5-cell cavities at 802 MHz, and two return arcs on either side. With an RF voltage of 75 MeV per linac a final electron energy of about 300 MeV is reached. The average beam current should be above 6 mA to explore the parameter range of the future LHeC. In this paper we present a preliminary optics layout.

TUPME062

Simulation and Analysis of Microbunching Instability in a High Repetition rate FEL Beam Delivery System

laser, simulation, linac, FEL

1709

J. Qiang, J.N. Corlett, P. Emma, C.E. Mitchell, M. Venturini
LBNL, Berkeley, California, USA

Funding: Work supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
Microbunching instability in the accelerator beam delivery system of an FEL can significantly degrade the electron beam quality and limit performance of the X-ray radiation. In this paper, we present detailed numerical simulation and analytical analysis of the microbunching instability in a high repetition rate X-ray FEL beam delivery system that is being studied at Lawrence Berkeley National Laboratory. Our results suggest that by using a flexible accelerator design and a laser heater, the effects of microbunching instability can be suppressed without significantly sacrificing the final electron beam quality.

TUPME067

Design Concept of a Gamma-gamma Higgs Factory Driven by Thin Laser Targets and Energy Recovery Linacs

laser, photon, target, collider

1721

Y. Zhang
JLAB, Newport News, Virginia, USA

Funding: Supported by the U.S. Department of Energy, Office of Nuclear Physics, under Contract No. DE-AC05-06OR23177.
A gamma-gamma collider has long been considered an option for a Higgs Factory. Such photon colliders usually rely on Compton back-scattering for generating high energy gamma photons and further Higgs bosons through gamma-gamma collisions. The presently existing proposals or design concepts all have chosen a very thick laser target (i.e., high laser photon intensity) for Compton scatterings. In this paper, we present a new design concept of a gamma-gamma collider utilizing a thin laser target (i.e., relatively low photon density), thus leading to a low electron to gamma photon conversion rate. This new concept eliminates most useless and harmful low energy soft gamma photons from multiple Compton scattering so the detector background is improved. It also greatly relaxes the requirement of the high peak power of the laser, a significant technical challenge. A high luminosity for such a gamma-gamma collider can be achieved through an increase of the bunch repetition rate and current of the driven electron beam. Further, multi-pass recirculating linac could greatly reduce the linac cost and energy recovery is required to reduce the needed RF power.

TUPWA015

The Study of Bunch Lengthening in Electron Storage Ring

impedance, synchrotron, storage-ring, luminosity

1757

Y. Li, L. Wang, Y. Zhang
IHEP, Beijing, People's Republic of China

The bunch length of electron storage ring of BEPCII was measured repeatedly during steady synchronous mode and streak camera was calibrated well. From the bench lengthening , the coupling impedance of the whole ring was estimated, which was according with theoretic impedance budget . Meanwhile, the small ap optics for improving the luminosity was feasible in collision mode form synchronous result .

TUPWA024

The Beam Gass Coulomb Scattering in Electron Storage Ring

scattering, simulation, radiation, synchrotron

1778

X.L. Yu, Z. Bai, W.W. Gao, W. Li, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Among the various factors which determine the beam life time of the HLSII electron storage ring, the beam loss due to the scattering on residual gas is simulated using MC method. The paper will give the process of elastic and inelastic scattering, and the probability of each scattering is calculated, then using MC sampling to decide which particles will participate in the collision. Tracking the beam with scattering of beam-gas included, the spatial distribution of beam will be obtained. Finally we will give the influence analysis of beam-gas scattering.

TUPWA041

Reduction of Secondary Electron (SEY) Yield Figures on Smooth Metallic Surfaces by Means of Magnetic Roughness

permanent-magnet, gun, radio-frequency

1799

M. Taborelli, F. Caspers, M. Mensi
CERN, Geneva, Switzerland
L.S. Aguilera, I. Montero
CSIC, Madrid, Spain

High secondary electron yield of metallic surfaces used in accelerator and also space applications is of general concern. In addition to several well known coating techniques and microscopic or macroscopic mechanical roughness (grooves) which may significantly increase microwave losses the concept of magnetic surface roughness has been proposed recently. In this concept a smooth and very well conductimg surface with low microwave losses is maintained, but underneath this surface a large number of tiny permanent magnets are located to build a rough magnetic equipotential structure. In this paper we present and discuss measurement of the SEY and the improvement in terms of SEY for different parameter ranges

TUPWA050

Effect of Transverse Coupling on Asymmetric Cooling in Compton Rings

emittance, laser, coupling, betatron

1823

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

Fast cooling of bunches circulating in a Compton ring is achieved by placing the collision point between electron bunches and laser pulses in a dispersive section and by, in addition, introducing a transverse offset between the laser pulse and the electron-beam closed orbit. Growth of the emittance in the dispersive transversal direction due to the additional excitation of betatron oscillations limits this type of cooling. Here we present the results of further studies on the fast cooling process, looking at the effect of the coupling of the transverse (betatron) oscillations. We first show theoretically that the transverse betatron coupling shortens the cooling time and hence reduces the steady-state energy spread of the electron beam, as well as the quantum losses. The theoretical estimates are then validated by simulations. Finally, a proof-of-principle experiment at the KEK ATF Damping Ring is proposed.

TUPWA058

Experimental Study of Soliton Wave Trains in Intense Electron Beams

space-charge, simulation, laser, induction

1835

Y. Mo, B.L. Beaudoin, D.W. Feldman, I. Haber, R.A. Kishek, P.G. O'Shea
UMD, College Park, Maryland, USA

Funding: Supported by the US Dept. of Energy, Office of High Energy Physics, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office.
Longitudinal perturbations in intense beams can lead to instabilities or degradation of beam quality, ultimately affecting the performance of accelerators, especially near the source where space charge is important. In this experimental study, conducted on the University of Maryland Electron Ring (UMER), large-amplitude perturbations are purposefully generated and their propagation observed over a long transport length. It is found that narrow, large-amplitude perturbations on a long-pulse beam develop into Korteweg-deVries (KdV) type soliton wave trains. Each peak in the wave train has a constant width and amplitude over a long propagation distance, with the amplitude inversely proportional to the square of the width. Furthermore, two such pulses are seen to interact with each other and emerge from the collision unchanged. The experimental data is compared with the KdV model and particle-in-cell simulations with good agreement. We induce perturbations using two methods: using photoemission to perturb the density at the cathode, or using an induction cell to directly perturb particle velocities.

TUPWA061

Observation at CesrTA of the Reduction of the Vertical Beam Size of the Lead Bunch in a Train Due to the Presence of a Precursor Bunch

positron, dipole, feedback, simulation

1841

M.G. Billing, K.R. Butler, G. Dugan, M.J. Forster, R.E. Meller, G. Ramirez, N.T. Rider, K.G. Sonnad, H.A. Williams
CLASSE, Ithaca, New York, USA
J.W. Flanagan
KEK, Ibaraki, Japan
R. Holtzapple, M. Randazzo
CalPoly, San Luis Obispo, California, USA
M.A. Palmer
Fermilab, Batavia, USA

Funding: Work supported by DOE Award DE-FC02-08ER41538, NSF Award PHY-0734867, PHY-1068662 and the Lepton Collider R&D Coop Agreement: NSF Award PHY-1002467.
Electron cloud-induced beam dynamics is being studied at CesrTA under various conditions. These measurements make use of instrumentation for the detection of the coherent self-excited spectrum for each bunch within the train and bunch-by-bunch vertical beam size. In the position spectrum coherent betatron dipole and head-tail motion is detectable for each individual bunch within the train. These techniques are utilized to study the electron cloud-related interactions, which cause the growth of coherent motion and beam size along the train. We report on the observations of the vertical enlargement of the first bunch(es) in 30 bunch-long trains. We also report that the addition of a precursor bunch following the train of bunches and before the start of the next train can counteract the vertical enlargement of the first bunch(es) in the train. Results from these observations will be presented.

TUPWA062

Dependence of Beam Instabilities Caused by Electron Clouds at CesrTA on Variations in Bunch Spacing and Chromaticity

damping, dipole, positron, resonance

1844

M.G. Billing, K.R. Butler, G. Dugan, M.J. Forster, R.E. Meller, M.A. Palmer, G. Ramirez, 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.W. Flanagan
KEK, Ibaraki, Japan

Funding: Work supported by DOE Award DE-FC02-08ER41538, NSF Award PHY-0734867 and the Lepton Collider R&D Coop Agreement: NSF Award PHY-1002467
Experiments have been performed at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) to probe the interaction of the electron cloud with a 2.1 Gev stored positron beam. The purpose of these experiments was to characterize the dependence of beam–electron cloud interactions on the bunch spacing and the vertical chromaticity. These experiments were performed on a 30-bunch positron train, at a fixed current of 0.75mA/bunch. The bunch spacing was varied between 4 and 28 ns at three different vertical chromaticity settings. The beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using: 1) a gated Beam Position Monitor (BPM) and spectrum analyzer to measure the bunch-by-bunch frequency spectrum of the bunch trains; 2) an x-ray beam size monitor to record the bunch-by-bunch, turn-by-turn vertical size of each bunch within the trains. In this paper we report on the observations from these experiments and analyze the effects of the electron cloud on the stability of bunches within these different trains.

TUPWA063

Dependence of Vertical Beam Dynamics Influenced by Electron Clouds at CesrTA on Variations in Bunch Spacing and Vertical Chromaticity

positron, synchrotron, emittance, feedback

1847

R. Holtzapple, R.F. Campbell, E.L. Holtzapple
CalPoly, San Luis Obispo, California, USA
M.G. Billing, K.R. Butler, G. Dugan, M.J. Forster, B.K. Heltsley, G. Ramirez, N.T. Rider, J.P. Shanks, K.G. Sonnad
CLASSE, Ithaca, New York, USA
J.W. Flanagan
KEK, Ibaraki, Japan

Funding: Work supported by DOE Award DE-FC02-08ER41538, NSF Award PHY-0734867, PHY-1068662 and the Lepton Collider R&D Coop. Agreement: NSF Award PHY-1002467
Experiments have been performed on the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) to probe the interaction of the electron cloud with a 2-Gev stored positron beam. The purpose of these experiments was to characterize the beam–electron cloud interactions by varying the vertical chromaticity and bunch spacing. These experiments were performed on a 30-bunch positron train, at a fixed current of 0.75mA/bunch, where the bunch spacing was varied between 4 and 28ns at three different vertical chromaticity settings. The vertical beam dynamics of the stored beam, in the presence of the electron cloud, was quantified using the x-ray beam size monitor (xBSM) that is used to measure the bunch-by-bunch, turn-by-turn vertical beam size of the bunch trains. In this paper, we report the results from these experiments and discuss the effects of the electron cloud on the CesrTA beam dynamics.

TUPWA071

Studies of Resistive Wall Heating at JLAB FEL

impedance, FEL, wiggler, resonance

1868

R. Li, S.V. Benson
JLAB, Newport News, Virginia, USA

Funding: Work supported by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
When the JLAB FEL is under CW operation, it had been observed that temperature rises over the wiggler vacuum chamber, presumably as the result of the power deposition on the resistive wall of the wiggler chamber. Previous analyses have been done on the resistive wall impedance for various cases, such as DC, AC, and anomalous skin effects*. Here we report an investigation on the beam kinetic energy losses for each of these cases. This study includes the non-ultrarelativistic effect on resistive wall loss, for both round pipe and parallel plates. We will present the comparison of our results with the measured data obtained during CW operation of the JLAB FEL. Other possible factors contributing to the measured heating will also be discussed.
* K. Bane and G. Stupakov, SLAC-PUB-10707, 2004.

TUPWA074

Studies of Ion Beam Instabilities for Low Energy RHIC Operations with Electron Cooling

ion, simulation, impedance, emittance

1871

G. Wang, M. Blaskiewicz, V. Litvinenko
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Electron cooling has the potential to compensate the emittance growth of the circulating ion beam due to intra-beam scattering at low energy. A test of electron cooling for RHIC low energy operations has been planned at IP2. Apart from the wakefield from the environment, the coherent interaction between the electron beam and ion beam could also play a role for the instability threshold. This work presents studies of ion beam stabilities in presence of coherent electron-ion interactions for the planned low energy RHIC electron-cooling test using the simulation code TRANFT.

TUPWO007

Investigation of the Magnetic Chicane of the New Short-Pulse Facility at the DELTA Storage Ring

undulator, laser, simulation, klystron

1889

R. Molo, J.A. Grewe, H. Huck, M. Huck, M. Höner, S. Khan, A. Schick, P. Ungelenk
DELTA, Dortmund, Germany

Funding: Supported by DFG, BMBF, and the Federal State NRW.
The new short-pulse facility at DELTA (a 1.5-GeV synchrotron light source) based on coherent harmonic generation (CHG) utilizes an electromagnetic undulator which can be configured as optical klystron (undulator – chicane – undulator). To optimize the CHG signal, the energy modulation of the electrons in the first undulator and the dispersion of the magnetic chicane (i.e. the R56 matrix element) have to be optimized. Since the R56 value of the present chicane is not sufficient, it is planned to rewire the magnetic coils to create a more efficient chicane. Simulations of the present chicane will be compared to measurements of the R56 matrix element and a new chicane configuration will be presented which increases the R56 value by a factor of ten.

TUPWO008

High-Current Beam Transport Simulations Including Gabor Lenses in Varying Non-Neutral Plasma States

simulation, focusing, plasma, space-charge

1892

M. Droba, H. Dinter, O. Meusel, D. Noll, U. Ratzinger, K. Schulte
IAP, Frankfurt am Main, Germany

The Gabor space charge lens has theoretically and experimentally been investigated at IAP for many years. Especially the application in high current, Low Energy Beam Transport (LEBT) sections seems efficient and attractive. The focusing properties and imaging quality of this lens type depend on the transverse and longitudinal confinement of the electron column. Different non-neutral plasma states have been observed and calculated. In general, they can be disturbed by the interaction with ion beams. This results in a shift and in a modification of the work function with a rise of aberrations and beam emittance growth. It is necessary to understand such processes for transport channels using intense ion beams to preserve the high beam brilliance. The beam transport simulations including Gabor lenses in various non-neutral plasma states will be presented and compared with experimental results.

TUPWO012

Relations Between Projected Emittances and Eigenemittances

emittance, beam-transport, quadrupole, coupling

1904

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

We give necessary and sufficient conditions which two sets of positive real numbers must satisfy in order to be realizable as eigenemittances and projected emittances of a beam matrix. The information provided by these conditions sets limits on what one can to achieve when designing a beam line to perform advanced emittance manipulations (for example, round-to-flat beam transformations).

TUPWO013

Non-linear Beam Transport Optics for a Laser Wakefield Accelerator

undulator, radiation, focusing, optics

1907

C. Widmann, V. Afonso Rodriguez, T. Baumbach, A. Bernhard, N. Braun, B. Härer, P. Peiffer, R. Rossmanith, W. Werner
KIT, Karlsruhe, Germany
O. Jäckel, M. Kaluza, M. Reuter
HIJ, Jena, Germany
M. Kaluza, M. Nicolai, T. Rinck, A. Sävert
IOQ, Jena, Germany
M. Scheer
HZB, Berlin, Germany

Funding: This work is funded by the German Federal Ministry for Education and Research under contract no. 05K10VK2 and no. 05K10SJ2
The transport and matching of electron beams generated by a Laser Wakefield Accelerator (LWFA) is a major challenge due to their large energy spread and divergence. The divergence in the range of one milli-radian at energies of some 100 MeV calls for strong focusing magnets. At the same time a chromatic correction of the magnets is needed due to the relative energy spread of a few percent. This contribution discusses in particular the layout of the beam transport optics for a diagnostic beam-line at the LWFA in Jena, Germany. The aim of this optics is to match the betatron functions and the non-zero dispersion to the x-dependent flux density amplitude of a non-planar undulator such that monochromatic undulator radiation is generated despite the large energy spread. The transport line is realized as a dogleg chicane involving several strong focusing quadrupoles. The chromatic error is compensated by additional sextupoles. To keep the setup as compact as possible the magnets are designed as combined function magnets. In this contribution the design and optimization of the transport optics, as well as its realization are presented.

TUPWO014

Downscaling the Energy of the MAMI-B Cascade Towards 100 MeV

injection, microtron, dipole, extraction

1910

M. Dehn, K. Aulenbacher, K.-H. Kaiser, H.-J. Kreidel, V. Schmitt
IKP, Mainz, Germany

Funding: Work supported by DFG (CRC 443/1044) and the German federal state of Rheinland-Pfalz
New experiments could benefit from energies of ~100 MeV, significantly lower than 180 MeV which is the lowest energy routinely available with the microtron cascade of MAMI-B. This article describes the difficulties which arise due to the drastically reduced injection energy of the first microtron (RTM-1) and presents the results of the beam tests which have been performed. We suggest a new beam extraction system from RTM-2 which will avoid these problems.

TUPWO029

Beam Line Design at the CAEP THz Free Electron Laser

cavity, emittance, laser, FEL

1937

P. Li, W. Bai, H. Wang
CAEP/IAE, Mianyang, Sichuan, People's Republic of China
X. Li
TUB, Beijing, People's Republic of China

China Academy of Physics (CAEP) is currently building a THz Free Electron Laser (THz-FEL) which serves as a radiation light sourse used for research in a variety of experimental fields. In this paper, we present the design of the beam line, which was accomplished using PARMELA and TRANSPORT code simulations. The accelerator consists of a 350 kV photocathode DC gun in conjunction with one cryomodule containing two 4-cell superconductiong RF cavities. The energy of the elctron beam is 7~8 MeV, and the maximum of the average beam current is 5 mA. A transverse emittance typically below 10 pi mm.mrad can be achieved.

TUPWO030

Beam-based Alignment Simulation on Flash-I Undulator

undulator, quadrupole, simulation, alignment

1940

D. Gu, Q. Gu, D. Huang, M. Zhang, M.H. Zhao
SINAP, Shanghai, People's Republic of China
M. Vogt, N.J. Walker
DESY, Hamburg, Germany

In order to ensure the SASE process can take place in the whole FLASH-I undulator section, a straight beam trajectory is mandatory which can only be achieved through beam-based alignment (BBA) method based on electron energy variations. In this paper, a detailed result of simulation is presented which demonstrate that the alignment can be achieved within accuracy of a few 10 μm after several iterations. The influence of Quadrupole and BPM offsets, magnet-mover calibration errors, quadrupole gradient errors are also discussed.

TUPWO034

Focusing Magnetic Field Design for a FEL Linac

linac, focusing, space-charge, solenoid

1949

Q.S. Chen, Q. Fu, T. Hu, B. Qin, B. Wu, H. Zeng
HUST, Wuhan, People's Republic of China
J. Li, Y.J. Pei
USTC/NSRL, Hefei, Anhui, People's Republic of China

A linac-based Free Electron Laser is planned to be built in Huazhong University of Science and Technology (HUST). As an important part of the whole project, the focusing magnetic field is carefully designed. Space-charge force is calculated at first to give a rough evaluation about the focusing field. Start-to-end simulation shows that the magnetic field has only great effect on spot size and phase space. With the final designed field, 10-ps-length pulse containing 200pC electrons can be got and the corresponding RMS emittance and RMS radius are 7 πmm•mrad and 0.25 mm, respectively. Finally, a new idea (double-peak scheme) is discussed and excitation current is proposed as the evaluation index.

TUPWO035

Physical Design of Beam Transport Line of a Compact Terahertz FEL

lattice, undulator, quadrupole, FEL

1952

H. Zeng, Q.S. Chen, Q. Fu, B. Qin, B. Wu, Y.Q. Xiong
HUST, Wuhan, People's Republic of China
G. Feng, Y.J. Pei
USTC/NSRL, Hefei, Anhui, People's Republic of China

The single pass, linac-based compact terahertz source at HUST is now in the physical design stage. To match Twiss parameters and dispersion function of the electron beam at the undulator entrance and get smaller beta function in the whole line, several lattices based on the double bending achromat(DBA) structure were discussed and the optimized design is given with beam dynamics results–calculated by MAD and Trace 3D.

TUPWO055

Phase Rotation Experiment at EMMA for testing Applicability of a Non-scaling FFAG for PRISM System

extraction, synchrotron, acceleration, background

1991

B.D. Muratori, J.K. Jones
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.T.P. D'Arcy
UCL, London, United Kingdom
J.K. Jones, B.D. Muratori
Cockcroft Institute, Warrington, Cheshire, United Kingdom
D.J. Kelliher, S. Machida
STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
H.L. Owen
UMAN, Manchester, United Kingdom
J. Pasternak
STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
J. Pasternak
Imperial College of Science and Technology, Department of Physics, London, United Kingdom

EMMA is the world’s first non-scaling FFAG, based at Daresbury Laboratory. EMMA has a very large acceptance and has demonstrated acceleration in the serpentine channel. PRISM (Phase Rotated Intense Slow Muon source) is a next generation muon to electron conversion experiment aiming to obtain intense quasi-monochromatic low energy muon beams by performing RF phase rotation in an FFAG ring. Current baseline design for PRISM applies the scaling FFAG ring, but an alternative machine could be based on a ns-FFAG principle. As the transverse-longitudinal coupling is present in ns-FFAGs due to a natural chromaticity, its effect on the final energy spread and beam quality needs to be tested. In order to gauge the expected results, an experiment was designed to be performed on EMMA. We report here the details of this experiment and the results gathered from EMMA operation.

TUPWO056

Modelling of the EMMA ns-FFAG Ring using GPT

space-charge, simulation, injection, closed-orbit

1994

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

EMMA (Electron Machine with Many Applications) is a prototype non-scaling Fixed-Field Alternating Gradient (ns-FFAG) accelerator whose construction at Daresbury Laboratory, UK, was completed in the autumn of 2010. The energy recovery linac ALICE serves as an injector for the EMMA ring, within an effective energy range of 10 to 20 MeV. The ring is composed of 42 cells, each containing one focusing and one defocusing quadrupole. Acceleration over many turns of the EMMA machine has recently been confirmed. In some cases the bunch will traverse upwards of 100 turns, at which point the effects of space-charge may be significant. It is therefore necessary to model the electron beam transport in the ring using a code capable of both calculating the effect of and compensating for space-charge. Therefore the General Particle Tracer (GPT) code has been used. A range of injection beam parameters have been modelled for comparison with experimental results and those of other codes. The simulated effects of space-charge on the tune shift of the machine are also compared with those expected from theory.

TUPWO059

Reducing Emittance of a H⁻ Beam in a Solenoid-based Low-energy Beam Transport through Numerical Modeling

simulation, solenoid, emittance, rfq

2000

J. von Stecher, D.L. Bruhwiler, B.T. Schwartz, S.A. Veitzer
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) subsystem is under development for the H⁻ linac front end of the Spallation Neutron Source. The LEBT design includes MHz frequency chopping of the partially neutralized H⁻ beam that can potentially lead to beam instabilities. We report results of numerical modeling using the parallel Vorpal framework for 3D electrostatic particle-in-cell (PIC) to simulate H⁻ beam dynamics in the LEBT, over multiple chopping events. We detail how the addition of a positively biased potential barrier near the entrance of the chopper can improve LEBT performance by eliminating chopper-induced emittance increases over many chopping events.
DLB is now at University of Colorado, Boulder

TUPWO061

Design of a Soft Orbit Bump for FEL Mirror Protection at Duke FEL/HIGS Facility

FEL, radiation, synchrotron, synchrotron-radiation

2006

H. Hao, J.Y. Li, S.F. Mikhailov, Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA

Funding: This work is supported in part by the US DOE grant no. DE-FG02-97ER41033.
In an oscillator Free-Electron Laser (FEL) with a high energy electron beam, it is critical to minimize harmful high-energy radiation on the downstream FEL mirror in order to increase its lifetime. At the High Intensity Gamma-ray Source (HIGS) facility at Duke University, effort has been devoted to developing a variety of techniques to reduce the amount of radiation on the FEL mirror. One of the most effective methods was the use of a set of adjustable in-vacuum apertures to block harmonic radiation from FEL wigglers. In recent studies, it was determined that the edge radiation from the end-of-the-arc bending magnet is the main source of UV/VUV and x-ray radiation which causes mirror damage. To mitigate this effect, a soft orbit bump is designed to change the displacement and angle of the electron beam around the end-of-the-arc area. This soft orbit bump is developed using the multi-objective optimization technique. Calculation shows the soft orbit bump can significantly reduce the flux of high energy photons on the FEL mirror. Study is also performed to determine the impact of this orbit bump on the injection, beam lifetime, and the FEL and gamma-ray operation at HIGS facility.

TUPWO065

Anomalously Long Bunches from the SLAC North Damping Ring

linac, simulation, klystron, damping

2015

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

The SLC damping ring provides emittance reduced beam to the beginning of the FACET accelerator. In measurements conducted during the 2012 FACET run, we find the bunch-length to be ~20% longer than canonical. A study is performed with longitudinal simulation code to determine the impact on the various stages of compression for FACET experimental running.

WEOAB102

CSR-driven Longitudinal Single Bunch Instability Thresholds

impedance, synchrotron, resonance, damping

2041

P. Kuske
BESSY GmbH, Berlin, Germany

According to Bane, et al.* threshold currents should follow a quite simple scaling law. More detailed theoretical results for the underlying shielded CSR-interaction have been performed for BESSY-II and the MLS and will be presented in comparison with observations at these storage rings. It is found that there are parameter regions where the instability is weak and thus thresholds depend on damping time and synchrotron tune. Theoretical findings are in surprisingly good agreement with most of the observed instability features.
* K.L. Bane, et al., Phys. Rev. ST-AB 13, 104402 (2010)

Slides WEOAB102 [0.779 MB]

WEOAB103

Experimental Observations of a Multi-stream Instability in a Long Intense Beam

simulation, space-charge, factory, background

2044

B.L. Beaudoin, S. Bernal, I. Haber, R.A. Kishek, T.W. Koeth
UMD, College Park, Maryland, USA

Funding: Supported by the US Dept. of Energy, Office of High Energy Physics, and by the US Dept. of Defense, Office of Naval Research and the Joint Technology Office.
We have observed evidence of a multi-stream instability in a long non-relativistic space-charge dominated beam evolving with an initial non-linear distribution and zero external longitudinal containment. This type of instability can be detrimental to intense accelerators that propagate rectangular distributions, such as in a ring with single or multi-bunch injection. The longitudinal forces in these intense bunches causes the beam to expand axially; in the case of the University of Maryland Electron Ring (UMER), the initial long bunch is injected to fill a fraction of the ring, coasting beyond the point where the head and tail overlap. Adjacent filaments at that point are separated in velocity space by 2cs and approach a separation of cs. The onset of the instability has been observed to depend on the injected beam current, bunch length, and other experimental factors. Comparisons with simple analytical calculations and PIC simulations have shown good agreement in the time to onset.

Slides WEOAB103 [1.681 MB]

WEZB101

Status of the European XFEL

linac, undulator, photon, gun

2058

M. Hüning
DESY, Hamburg, Germany

The European XFEL is one of the world's largest accelerators presently under construction. The facility includes a 17.5 GeV superconducting linac with more than 3 km of electron beam transport lines and up to 5 FEL undulators. In mid-2013 the underground civil construction will finish. With most of the large scale production in full swing and first accelerator components installed, this talk should present the XFEL facility status and plans for accelerator commissioning including prospects for first XFEL experiments in Hamburg.

Slides WEZB101 [16.980 MB]

WEZB102

Overview of Seeding Methods for FELs

FEL, radiation, undulator, laser

2063

S. Reiche
PSI, Villigen PSI, Switzerland

In recent years enormous progress has been achieved in the theoretical understanding and experimental demonstration of FEL seeding. The state of the art for FEL seeding should be reviewed and compared to HHG, HGHG, EEHG techniques. The potential of various seeding methods and their promise to produce radiation pulses that approach the transform limit in a range of experimental configurations at different user facilities should be explored.

Slides WEZB102 [4.238 MB]

WEODB101

X-ray Spectra and Peak Power Control with iSASE

FEL, undulator, laser, radiation

2068

J. Wu, F.-J. Decker, Y. Feng, J. Krzywinski, H. Loos, A.A. Lutman, A. Marinelli, H.-D. Nuhn, C. Pellegrini, D.F. Ratner, D.H. Zhang, D. Zhu
SLAC, Menlo Park, California, USA

Funding: Work is supported by U.S. Department of Energy, Office of Basic Energy Sciences, under Contract DE-AC02-76SF00515.
We report the first measurement of spectral line-width reduction in a self-amplified spontaneous emission (SASE) X-ray free-electron laser (FEL) obtained by introducing repeated delays of the electron bunch with respect to the radiation field pulse. The improved longitudinal coherence obtained by this method reduces the intensity spiking effect characteristic of a SASE FEL. The electron-photon delays introduced along the FEL undulator mix the spikes phase and amplitude, increasing the cooperation length and generating a smaller bandwidth than in the conventional SASE mode of operation of an FEL. We call this mode of operation, based on repeated electron-photon delays, ‘‘improved SASE'' (iSASE). We also show with theoretical and simulation analysis that in the iSASE mode it is possible to choose the separation and magnitude of the delays to obtain a nearly transform limited X-ray pulse. This analysis is carried out using a time dependent, one-dimensional model and with GENESIS numerical simulation, including three-dimensional effects.

Slides WEODB101 [7.647 MB]

WEODB102

Generating Polarization Controllable FELs at Dalian Coherent Light Source

FEL, polarization, controls, undulator

2071

T. Zhang, H.X. Deng, D. Wang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China
D.X. Dai, G.R. Wu, X.M. Yang, W.Q. Zhang
DICP, Dalian, People's Republic of China

Funding: 973 Program of China (2011CB808300), NSFC 11175240 and 11205234.
The property of the FEL polarization is of great importance to the user community. FEL pulses with ultra-high intensity and flexible polarization control ability will absolutely open up new scientific realms. In this paper, several polarization control approaches are presented to investigate the great potential on Dalian coherent light source, which is a government-approved novel FEL user facility with the capability of wavelength continuously tunable in the EUV regime of 50-150 nm. The numerical simulations show that both circularly polarized FELs with highly modulating frequency and 100 microjoule level pulse energy could be generated at Dalian coherent light source*.
*T. Zhang, et al., FEL Polarization Control Studies on Dalian Coherent Light Source, Chinese Physics C, 2013, to be published.

Slides WEODB102 [6.131 MB]

WEXB201

Intense Highly Charged Heavy Ion Beam Production

ion, ion-source, plasma, heavy-ion

2077

T. Nakagawa
RIKEN/RARF/CC, Saitama, Japan

With increase of applications of heavy ions in the various fields, production of intense beam of highly charged heavy ions form the ion sources become more and more important. For example, ion sources are required to produce intense dc beams of the highly charged heavy ions for the accelerator facilities of radio isotope beam production and the intense short pulsed beams for injection into synchrotrons. Additionally, in these applications, the ion sources face several important matters to be improved for meeting the requirements, such as source lifetime, reliability, current stability, and beam emittance. For these purposes, several high performance ion sources, which include ECR ion sources, electron beam ion sources and laser ion sources, for production of the intense beam (dc and pulsed) of highly charged heavy ions have been constructed and achieved remarkable breakthrough in the past decade. In this contribution, state-of-the-art ion sources for production of intense highly charged heavy ion beams are reviewed. Future perspective is also discussed.

Slides WEXB201 [4.395 MB]

WEOAB202

JEMMRLA - Electron Model of a Muon RLA with Multi-pass Arcs

linac, quadrupole, dipole, optics

2085

S.A. Bogacz, G.A. Krafft, V.S. Morozov, Y. Roblin
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We propose a demonstration experiment for a new concept of a ‘dogbone’ RLA with multi-pass return arcs – JEMMRLA (Jlab Electron Model of Muon RLA). Such an RLA with linear-field multi-pass arcs was introduced for rapid acceleration of muons for the next generation of Muon Facilities. It allows for efficient use of expensive RF while the multi-pass arc design based on linear combined-function magnets exhibits a number of advantages over separate-arc or pulsed-arc designs. Here we describe a test of this concept by scaling a GeV scale muon design for electrons. Scaling muon momenta by the muon-to-electron mass ratio leads to a scheme, in which a 4.5 MeV electron beam is injected in the middle of a 3 MeV/pass linac with two double-pass return arcs and is accelerated to 18 MeV in 4.5 passes. All spatial dimensions including the orbit distortion are scaled by a factor of 7.5, which arises from scaling the 200 MHz muon RF to a readily available 1.5 GHz. The hardware requirements are not very demanding making it straightforward to implement. Such an RLA may have applications going beyond muon acceleration: in medical isotope production, radiation cancer therapy and homeland security.

Slides WEOAB202 [1.485 MB]

WEOAB203

The PEPPo Concept for a Polarized Positron Source

positron, polarization, target, photon

2088

E. J-M. Voutier
LPSC, Grenoble, France

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Polarized positron beams are identified as an essential ingredient for the experimental program at the next generation of lepton accelerators (JLab, Super KEK B, ILC, CLIC). A proof-of-principle experiment for a new method to produce polarized positrons has recently been performed at the Jefferson Laboratory. The PEPPo (Polarized Electrons for Polarized Positrons) concept relies on the production of polarized e⁺e⁻ pairs from the bremsstrahlung radiation of a longitudinally polarized electron beam interacting within a high Z conversion target. The experiment was performed at the injector of the CEBAF accelerator at JLab and investigated the polarization transfer of an 8.3 MeV/c polarized electron beam to positrons produced in varying production target thicknesses. A dedicated new beam-line was constructed to produce, collect and transport positrons in the momentum range of 3.2 MeV/c to 6.2 MeV/c to a polarized iron target for polarization measurements. This technique potentially opens a new pathway for both high energy and thermal polarized positron beams. This presentation will discuss the PEPPo concept, the motivations for the experiment and the preliminary experimental results.
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.

Slides WEOAB203 [4.102 MB]

WEOBB201

Commissioning of the X-band Transverse Deflector for Femtosecond Electron/X-Ray pulse Length Measurements at LCLS

FEL, undulator, diagnostics, klystron

2091

Y.T. Ding, C. Behrens, J.C. Frisch, Z. Huang, P. Krejcik, J.R. Lewandowski, H. Loos, J.W. Wang, M.-H. Wang, J.J. Welch
SLAC, Menlo Park, California, USA
C. Behrens
DESY, Hamburg, Germany

X-ray free-electron lasers provide ultrashort x-ray pulses from several to a few hundred femtoseconds for multidisciplinary users. However, tremendous challenges remain in the measurement and control of these ultrashort pulses with femtosecond precision, for both the electron beam and the x-ray pulses. A new diagnostic scheme adding a transverse radio-frequency deflector at the end of the linac coherent light source (LCLS) undulator beamline has been proposed*. Two 1-m long deflecting structures have been installed at LCLS during the summer of 2012. Installation of the high power RF components including the klystron, waveguide, RF controls etc. is proceeding and commissioning is scheduled for March 2013. We report the latest progress of the commissioning of the deflector at LCLS.
* Y. Ding et al., Phys. Rev. ST Accel. Beams 14, 120701 (2011)

Slides WEOBB201 [4.199 MB]

WEOBB202

Ultra-fast Data Acquisition System for Coherent Synchrotron Radiation Based on Superconducting Terahertz Detectors

synchrotron, radiation, controls, storage-ring

2094

C.M. Caselle, M. Hofherr, K.S. Ilin, V. Judin, A. Kopmann, A. Menshikov, A.-S. Müller, M. Siegel, N.J. Smale, P. Thoma, M. Weber, S. Wuensch
KIT, Eggenstein-Leopoldshafen, Germany
B.M. Balzer, S. Cilingaryan
Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany

The ANKA synchrotron radiation source located at the Karlsruhe Institute of Technology in Germany operates in the energy range between 0.5-2.5GeV and provides coherent synchrotron radiation. To resolve the ultra-short terahertz pulses emitted by a single bunch, thin YBCO superconducting film detectors have been developed. A response time of 45ps was determined as the FWHM at the output of the analog amplifier. A novel and high accuracy data acquisition architecture for sampling of the individual ultra-short terahertz pulses combined with real-time data processing based on GPUs for coherent synchrotron radiation is presented. The digitizer board is a made-in-house board designed for sampling of the fast pulse signals with pulse width between few tens of picosecond until 100ps. For each terahertz pulse five samples are acquired with a minimum sampling time of 3ps. A prototype setup with terahertz YBCO detectors, digitizer boards and the high-throughput FPGA framework has been successfully developed and tested at ANKA. The overview of the experimental setup including the YBCO detector technology and the preliminary results with single and multi-bunch filling pattern will be discussed.

Slides WEOBB202 [2.416 MB]

WEIB201

Industrial Accelerators

ion, neutron, radiation, linac

2100

R.W. Hamm, M.E. Hamm
R&M Technical Enterprises, Pleasanton, California, USA

Particle accelerators, originally developed for basic science research, are increasingly being employed for industrial applications, with the production of these systems itself a worldwide business conducted by more than 70 companies and institutes. Collectively these entities ship more than 1000 systems per year. The industrial applications of these accelerators cover a broad range of business segments from low energy electron beam systems for welding, machining, and product irradiation to high energy cyclotrons and synchrotrons for radioisotope production and synchrotron radiation production. This talk is a review of these business segments and their impact on our lives and the economy. It will also cover new accelerator technology under development that will be used by industry in the future and the predicted growth in the various business segments.

Slides WEIB201 [3.937 MB]

WEIB205

Promoting Local Economic Development by an Integration of Industry, Teaching and Research of Compact Low Energy Accelerators

radiation, permanent-magnet, high-voltage, HOM

2119

M. Fan, D.Z. Chen, J. Huang, D. Li, K.F. Liu, B. Qin, Y.Q. Xiong, J. Yang, T. Yu
HUST, Wuhan, People's Republic of China
H.Q. Gao
Hubei University of Science and Technology, Hubei, People's Republic of China

Huazhong University of Science and Technology has been carrying out R&D of compact low energy accelerators by integrating industry, teaching and research to promote local economic development supported by both national and provincial government and local enterprises. Currently, the projects include: compact medical cyclotron, electron irradiation accelerators, etc. The industry of non-power nuclear energy based on low energy particle accelerator has also drawn attention from the provincial government of Hubei and municipal government of Xianning. Meanwhile, a series of lectures about nuclear science and nuclear safety were hosted to help the public better understand nuclear technology and to wipe out fears of nuclear energy. At the moment, the application of non-power nuclear energy with based on compact low energy accelerator is developing into an industry chain in the area of central China.

Slides WEIB205 [2.311 MB]

WEPWA001

Wigglers at Danfysik

wiggler, damping, radiation, emittance

2123

C.W.O. Ostenfeld, M. Pedersen
Danfysik A/S, Taastrup, Denmark

In the past 2 years, a number of insertion devices have been designed, assembled and tested at Danfysik. They are used for a variety of applications at free electron lasers and synchrotron radiation facilities. In this paper, we highlight 3 different wiggler projects: A 2.0 T wiggler for Astrid-II in Århus, Denmark, a fixed-gap electromagnetic wiggler for Helmholtz Center Dresden-Rossendorf, and 6 identical damping wigglers for NSLS-2 at Brookhaven National Laboratory (BNL). For the Astrid-2 facility in Aarhus, Denmark, we have designed and built a 6 period wiggler, with a peak field of 2.0 T. The magnetic design and performance is presented and discussed. As part of the ELBE THz facility, at Helmholtz Center Dresden-Rossendorf, we have designed and built a fixed-gap electromagnetic wiggler, with 300 mm period length, and a peak field of 0.39 T. We present the design and magnetic results. For the NSLS-2 project at BNL, damping wigglers are an integral part of the design, both as a means of reducing the emittance, but also as a source of intense radiation sources for users. We present the mechanical and magnetic design, as well as magnetic results obtained for the wigglers.

WEPWA005

Experimental Characterization of the Coherent Harmonic Generation Source at the DELTA Storage Ring

laser, radiation, undulator, synchrotron

2132

M. Huck, H. Huck, M. Höner, S. Khan, R. Molo, A. Schick, P. Ungelenk
DELTA, Dortmund, Germany
S. Cramm, L. Plucinski, C.M. Schneider
Forschungszentrum Jülich, Peter-Gruenberg-Institut-6, Jülich, Germany
S. Döring, L. Plucinski, C.M. Schneider
Universität Duisburg-Essen, Duisburg, Germany

Funding: Work supported by DFG, BMBF, and by the Federal State NRW.
The short-pulse facility at the 1.5-GeV synchrotron light source DELTA, operated by the TU Dortmund University, generates coherent VUV and THz radiation by Coherent Harmonic Generation (CHG). Here, a femtosecond laser pulse interacts with an electron bunch in an undulator causing a periodic energy modulation and subsequent micro-bunching, which gives rise to coherent radiation at harmonics of the seed wavelength. Rather than using Ti:Sapphire laser pulses at 795 nm directly, the second harmonic is employed for seeding since 2012. After significant modifications of the seed laser beamline and the dispersive chicane to improve the microbunching, the last commissioning steps include characterization of the CHG radiation and preparing the experimental setup at an existing VUV beamline for time-resolved photoemission spectroscopy. In this paper, the status of the project and recent experimental results are presented.

WEPWA006

Beam Heat Load Measurements with COLDDIAG at the Diamond Light Source

synchrotron, synchrotron-radiation, radiation, impedance

2135

S. Gerstl, S. Casalbuoni, A.W. Grau, T. Holubek, D. Saez de Jauregui, R. Voutta
KIT, Eggenstein-Leopoldshafen, Germany
R. Bartolini, M.P. Cox, E.C. Longhi, G. Rehm, J.C. Schouten, R.P. Walker
Diamond, Oxfordshire, United Kingdom
M. Migliorati, B. Spataro
INFN/LNF, Frascati (Roma), Italy

Understanding the heat load from an electron beam is still an open issue for the cryogenic design of superconducting insertion devices. COLDDIAG, a cold vacuum chamber for diagnostics was designed and built specially for this purpose. With the equipped instrumentation, which covers temperature sensors, pressure gauges, mass spectrometers as well as retarding field analyzers it is possible to measure the beam heat load, total pressure, and gas content as well as the net flux and energy of particles hitting the chamber walls. Following a failure after its first installation in November 2011, COLDDIAG was subsequently reinstalled in the Diamond storage ring in August 2012. We report on the preliminary results that have been obtained since then.

WEPWA010

FLUTE: A Versatile Linac-based THz Source Generating Ultra-short Pulses

radiation, linac, laser, gun

2147

M.J. Nasse, E. Huttel, S. Marsching, A.-S. Müller, S. Naknaimueang, R. Rossmanith, R. Ruprecht, M. Schreck, M. Schuh, M. Schwarz, P. Wesolowski
KIT, Karlsruhe, Germany
R.W. Aßmann, M. Felber, K. Flöttmann, M. Hoffmann, H. Schlarb
DESY, Hamburg, Germany
H.-H. Braun, R. Ganter, L. Stingelin
PSI, Villigen PSI, Switzerland

FLUTE is a linac-based accelerator test facility and a THz source currently being constructed at KIT with an electron beam energy of ~41 MeV. It is designed to cover a large charge range from a few pC to ~3 nC. FLUTE is optimized to provide ultra-short electron bunches with an RMS length down to a few fs. In this contribution, we focus on the layout of the machine from the RF gun & gun laser over the linac and the compressor to the THz beamline for the generation of coherent synchrotron, transition and edge radiation (CSR, CTR, CER).

Poster WEPWA010 [0.802 MB]

WEPWA011

Injector Linac for the MESA Facility

linac, booster, SRF, target

2150

R.G. Heine, K. Aulenbacher
IKP, Mainz, Germany

Funding: Work supported by the German Federal Ministery of Education and Research (BMBF) and German Research Foundation (DFG) under the Cluster of Excellence "PRISMA"
In this paper we present several possible configurations of an injector linac for the upcoming Mainz Energy-recovering Superconducting Accelerator (MESA)* and discuss their suitability for the project.
*R. Heine, K. Aulenbacher, R. Eichhorn "MESA - Sketch of An Energy Recovery Linac For Nuclear Physics Experiments At Mainz" IPAC 12, New Orleans, USA, 2012, p.1993, TUPR073

WEPWA012

Preliminary Design of Transfer Lines for the ILSF Accelerator Complex

booster, storage-ring, linac, synchrotron

2153

H. Ghasem
IPM, Tehran, Iran
E. Ahmadi, F. Saeidi
ILSF, Tehran, Iran

There are two transfer lines (T-lines) which link the Iranian Light Source Facility (ILSF) accelerator complex to gather. Several criterias have been considered in design stage of the T-lines. This paper gives linear optimization results of the designed T-lines based on the first layout of the ILSF.

WEPWA013

Injection Scheme into the High Field ILSF Storage Ring

kicker, injection, storage-ring, booster

2156

H. Ghasem
IPM, Tehran, Iran
E. Ahmadi, F. Saeidi
ILSF, Tehran, Iran

The injection system into a storage ring of a synchrotron radiation facility significantly affects quality of the electron beam and the radiated x-ray. The extracted 3 GeV electron beam from the booster synchrotron of the ILSF is transferred via the BTS transfer line and injected into the ILSF storage ring based on high field lattice structure. This paper describes the injection procedure into the ILSF storage ring and gives the electron tracking results of the injected beam.

WEPWA016

Production of Intense High Energy Gamma Beam for LEPS2 Project at SPring-8

laser, injection, storage-ring, scattering

2162

T. Yorita, T. Hotta, N. Muramatsu, T. Nakano, M. Oka, M. Yosoi
RCNP, Osaka, Japan
S. Daté, Y. Ohashi, H. Ohkuma, M. Oishi, Y. Okayasu, M. Shoji, S. Suzuki, Y. Taniuchi
JASRI/SPring-8, Hyogo-ken, Japan

Construction of new beam line for LEPS2 Project at SPring-8 has been done and development is now undergoing. LEPS2 is the project for high energy hadron physics using intense high energy gamma beam as probe. The gamma beam is produced by laser backward Compton scattering with injecting high power UV laser into the 8 GeV electron beam on long straight section of SPring-8 storage ring. The target intensities are ~10⁷/s for E_γ=2.4 GeV, ~10⁶/s for E_γ=2.9 GeV.

WEPWA017

Development of Laser-Compton X-ray Source using Optical Storage Cavity

laser, cavity, booster, linac

2165

K. Sakaue, M. Washio
Waseda University, Tokyo, Japan
M.K. Fukuda, Y. Honda, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

Funding: Work supported by the Quantum Beam Technology Program of MEXT and JSPS Grant-in-Aid for Young Scientists (B) 23740203
We have been developing a pulsed-laser storage technique in a super-cavity for a compact x-ray sources. The pulsed-laser super-cavity enables to make high peak power and small waist laser at the collision point with the electron beam. We already obtained a pulse-train x-rays through the laser-Compton scattering between a multi-bunch electron beam and an optical super-cavity. And also, we performed a X-ray imaging via laser-Compton X-ray. On these successful results, we decided to upgrade our system for increasing X-ray flux by 3-order of magnitudes for practical use. For an optical cavity, we designed 4-mirrors bow-tie cavity in order to increase the power. On the other hand, electron accelerator was also upgraded to increase the bunch number in the train. We use 3.6cells rf-gun and 12cell standing wave booster linac. As a result, 2-order increase of X-ray flux was achieved. Design of upgraded our laser-Compton X-ray source, the results of X-ray experiments and future prospective will be presented at the conference.

WEPWA020

Laser Electron Storage Ring for TTX

cavity, laser, storage-ring, quadrupole

2171

H.S. Xu, W.-H. Huang, C.-X. Tang, L.X. Yan, Y. You
TUB, Beijing, People's Republic of China
D. Jehanno, Z.F. Zomer
LAL, Orsay, France
S.-Y. Lee
IUCEEM, Bloomington, Indiana, USA

Tsinghua Thomson scattering X-ray (TTX) source, proposed by Tsinghua University, is a hard x-ray source with multi-application in condensed matter physics, etc. The TTX is composed of an S-band photocathode RF gun and a SLAC type 3m travelling wave Linac, and a femto-second tera-watt laser system drives the photocathode. The TTX source is in operation. To extend the capability of TTX, we plan to design a ring based system to increase the photon flux. In this paper, we report the design of the compact electron storage ring and optical cavity, expected performance, and future prospects.

WEPWA021

X-ray Spectra Reconstruction with HOPG Crystal on TTX

photon, scattering, simulation, laser

2174

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

Thomson Scattering sources, as the new generation of bright X-ray sources, have great application potential in many respects. Traditional spectra measurement methods, applied to measured the spectra of Thomson Scattering source, are troublesome as the X-ray beam is too intense to cause pile up problems. In this article, we use the HOPG crystal to reconstruct the X-ray spectra of Tsinghua Thomson X-ray source (TTX) through Braggs law. This method can get reasonable results with single or several shots, with high energy resolution. We also compare the experiment results of this method with the reconstructed spectra by analyzing the attenuation data of the X-ray beam in silicon , and these two results agree well with each other.

WEPWA024

Study of an Electron Gun for Terahertz Radiation Source

gun, cathode, focusing, radiation

2184

J. Li, C. Li, Y.J. Pei, L. Shang
USTC/NSRL, Hefei, Anhui, People's Republic of China
Q.S. Chen, T. Hu
HUST, Wuhan, People's Republic of China
G. Feng
DESY, Hamburg, Germany

With the aim to obtain short-pulse bunches with high peak current for a terahertz radiation source, an RF gun with independently tunable cells (ITC) was employed. As the electron source of the ITC RF gun, a grid-control DC gun plays a key role, the performance of which determines the beam quality in the injector and transport line. In order to make the beam well compressed in the ITC RF gun, the energy of the electrons acquired from the grid-control DC gun should be 15 KeV at most. A proper structure of the grid-gun is shown to overcome the strong space charge force on the cathode, which is able to generate 1us beam with 4.5A current successfully. Simulations considering the grid net are also introduced.

WEPWA033

The Magnetic Performance of Two Undulators for HLS

undulator, polarization, multipole, vacuum

2202

W. Zhang, Q.G. Zhou
SINAP, Shanghai, People's Republic of China
H.F. Wang
SSRF, Shanghai, People's Republic of China

An elliptically polarized undulator and an in vacuum undulator for HLS have been built at SSRF. The magnetic design of the two Undulators is reviewed. Measurements of the complete undulators are described. Results of performance optimization, including minimization of optical phase error, trajectory wander and integrated multipoles with magic fingers are presented.

WEPWA035

Design of a Superconducting Undulator Magnet Prototype for SSRF

undulator, superconductivity, synchrotron, storage-ring

2205

Z.C. Zhang, J. Cui, J.Y. Jiang, M. Li, W. Li, J.P. Xu, J.J. Xu, J.F. Yu
SINAP, Shanghai, People's Republic of China

Funding: Project 11275254 supported by National Natural Science Foundation of China.
A 0.65 T NbTi superconducting undulator magnet prototype with a period length of 16 mm and a period number of 5 for SSRF is designed. The magnetic field simulation shows that it is possible to obtain a peak field of 0.6 T on the beam axis at a magnetic gap of 9 mm, with a current density of 800A/mm2 in the superconducting coils. Two coil formers are machined from SAE10¹⁸ stainless steel and coated with TiO2 for insulation. The dimension of the grooves of the coil windings in the coil formers is 5 mm x 10 mm. Formvar insulated NbTi superconducting wires with a diameter of 0.6 mm are used for the 128 turn coils per core groove. A five periods core of NbTi superconducting magnet is machined from SAE1018 stainless steel and winded with copper wires.

WEPWA044

Electron Trajectories in a Three-dimensional Undulator Magnetic Field

undulator, focusing, radiation, simulation

2223

N.V. Smolyakov, S.I. Tomin
NRC, Moscow, Russia
G. Geloni
XFEL. EU, Hamburg, Germany

In this contribution we present an analysis of electron trajectories in the three dimensional magnetic field from a planar undulator. The electron trajectory is influenced by the focusing properties of the undulator field. In the European XFEL case, long segmented undulators (21 segments for the SASE3 beamline to 35 for SASE1 and SASE2) are planned to be installed, with quadrupole lenses between different segments. These focusing properties should be taken into account in simulations of spontaneous radiation, which constitutes the background signal of the FEL. The ideal magnetic field of an undulator can be described by a sinusoidal vertical magnetic field on the undulator axis, and by horizontal and longitudinal field components that appear out of axis. Exploiting this description for the ideal case, an experimentally measured magnetic field is accounted for by solving the differential equations of motion. The electrons' trajectories for the experimentally measured magnetic field were also simulated numerically. To that aim, a computer code was written, which relies on the Runge-Kutta algorithm. The analytical and numerical methods show a good agreement.

WEPWA047

Longitudinal Stability of Multiturn ERL with Split Accelerating Structure

linac, simulation, cavity, resonance

2226

Ya.V. Getmanov, O.A. Shevchenko, N. Vinokurov
BINP SB RAS, Novosibirsk, Russia
T. Atkinson
HZB, Berlin, Germany
N. Vinokurov
KAERI, Daejon, Republic of Korea

Some modern projects of the new generation light sources use the conception of multipass energy recovery linac with split (CEBAF-like) accelerating structures. One of the advantages of these light sources is the possibility to obtain a small longitudinal beam size. To help reduce it, the longitudinal dispersion should be non-zero in some arcs of the accelerator. However small deviations in voltages of the accelerating structures can be enhanced by induced fields from circulating bunches due to the dependence of the flight time on the energy spread and the high quality factor of the superconducting radio-frequency cavities. Therefore, instabilities related with interactions of the electron bunches and longitudinal modes of the cavities can develop in the installation. Stability conditions for the interactions with fundamental accelerating mode of the split accelerating system are discussed. Numerical simulations are made for two projects - MARS and FSF.

WEPWA052

A Gun to Linac Operation Analysis of the Taiwan Light Source Injector

linac, factory, gun, synchrotron

2235

H.C. Chen, H.H. Chen, S. Fann, S.J. Huang, J.A. Li, C.C. Liang, Y.K. Lin, Y.-C. Liu
NSRRC, Hsinchu, Taiwan

A response surface methodology (RSM) was used to study the gun to linac optimization process of the Taiwan Light Source (TLS) injector at the National Synchrotron Radiation Research Center (NSRRC). A study model, based on artificial neural network (ANN) theory, which uses electron beam tuning knobs as variables, was constructed. An optimization procedure was developed by designating electron beam efficiency as the objective function and the selected beam tuning knobs as the variables. The theoretical model and optimization procedure were both implemented to evaluate the model. By properly applying the constructed optimization procedure, the beam efficiency was improved. This report outlines the details of the gun to linac optimization process experiment.

WEPWA055

Multipole and End-field Shimming Results of EPU46 at the TPS

multipole, quadrupole, undulator, polarization

2244

T.Y. Chung, C.-H. Chang, J. Chen, J.C. Huang, C.-S. Hwang, J.C. Jan, F.-Y. Lin
NSRRC, Hsinchu, Taiwan

Multipole error and the first and second integrals of EPU46 require shimming to fulfill the tolerance requirements of beam dynamics. In this paper, we describe the field correction, including central-field and end-field shimming procedures, and the results for EPU46 at TPS. End-pole shimming for the first and second integrals serve to adjust the beam trajectory, and magic fingers to decrease the multipole error. For the active multipole shimming for undulators of type Apple II, a trim-long-coil array is used to compensate for multipole error. This scheme efficiently eliminates a phase-dependent skew quadrupole error.

WEPWA058

Operation of the NSRRC 2998 MHz Photo-cathode RF Gun

gun, laser, cathode, cavity

2247

A.P. Lee, M.C. Chou, J.-Y. Hwang, W.K. Lau
NSRRC, Hsinchu, Taiwan
P. Chiu, N.Y. Huang, P. Wang
NTHU, Hsinchu, Taiwan

We are developing the photoinjector technology for single pass high gain FEL research at NSRRC. A gun test facility(GTF) equipped with a 35 MW, S-band high power pulsed klystron as well as a 300 uJ, UV driver laser has been constructed for testing photo-cathode rf guns. Recently, a 2998 MHz, 1.6-cell photo-cathode rf gun has been fabricated in house and is being tested at the NSRRC GTF. Details of this setup will be described and the operational performance of this electron gun will be reported.

WEPWA059

Operation of the Drive Laser System for the 2998 MHz NSRRC Photoinjector

laser, gun, cathode, target

2250

M.C. Chou, W.K. Lau, A.P. Lee
NSRRC, Hsinchu, Taiwan

A 266nm UV laser system has been installed as the drive laser of the NSRRC 2998 MHz photo-cathode rf gun. We will report our experiences on using such laser system for rf gun beam test. UV optics for laser beam transport as well as shaping technique we used for emittance preservation will also be presented.

WEPWA060

The Kharkov X-ray Generator Facility NESTOR

storage-ring, lattice, controls, injection

2253

A.A. Shcherbakov, V.P. Androsov, N. Ayzatsky, V.N. Boriskin, E.V. Bulyak, A.N. Dovbnya, P. Gladkikh, A.N. Gordienko, V.A. Grevtsev, A. Gvozd, V.E. Ivashchenko, A.A. Kalamayko, I.I. Karnaukhov, I.M. Karnaukhov, V.P. Kozin, V.A. Kushnir, V.P. Lyashchenko, V.S. Margin, N.I. Mocheshnikov, V.V. Mytrochenko, A. Mytsykov, I.M. Neklyudov, T.F. Nikitina, F.A. Peev, O.V. Ryezayev, V.L. Skirda, V.A. Skomorokhov, Y.N. Telegin, V.I. Trotsenko, A.Y. Zelinsky, O.D. Zvonarjova
NSC/KIPT, Kharkov, Ukraine
J.I.M. Botman
TUE, Eindhoven, The Netherlands
I.V. Drebot
LAL, Orsay, France

The last few years the sources of the X-rays NESTOR based on a storage ring with low beam energy and Compton scattering of intense laser beam are under design and development in NSC KIPT. The main task of the project is to develop compact intense X-ray generator on the base of relatively cheap accelerator equipment and up-to-date laser technologies. The paper is devoted to description of the last results on construction and commissioning of the facility.

WEPWA064

Simulations of the ALICE ERL

FEL, linac, simulation, space-charge

2265

J.K. Jones, D.J. Dunning, F. Jackson, J.W. McKenzie, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

ALICE is a low-energy Energy Recovery Linac operated at Daresbury Laboratory in Cheshire, UK. The ALICE injector is based around a 350 kV DC photo-cathode electron gun. With an operating voltage of 325 keV, electron dynamics in the ALICE injector are space-charge dominated and highly non-linear, and this complicates simulations of the beam dynamics in this region. With an intermediate energy of 6.5 MeV, and a final ring energy of 27.5 MeV, the space-charge effects in the rest of the machine can also not be ignored. In this paper we summarise some of the work that has been performed to understand and optimise the simulations of the ALICE ERL, in several different operating modes, and using several different modelling codes.

WEPWA072

Design and Commissioning of Chasman-Green Double Bend Achromatic Lattice Linear Transport Line at the University of Hawai'i MkV Accelerator Facility

dipole, quadrupole, focusing, diagnostics

2280

B.T. Jacobson, J. Madey, P. Niknejadi
University of Hawaii, Honolulu, HI, USA

The design of the Double Bend Achromat (DBA) lattice was originally motivated by the desire to increase the brightness of a synchrotron ring by storing a low emittance electron beam*. Alternating the direction of the bends in the DBA lattice turns the ring into a linear transport line, which has advantages over the straight transport lines typically used in linac FEL's. The dipoles in the DBA cells provide synchrotron images of the electron beam, a real-time non-destructive diagnostic during operation. As in circular machines, sections between DBA cells provide a low-emittance dispersion free beam for insertion devices such as FEL's and inverse Compton backscattering sources. This paper describes an example linear DBA, which has been designed and commissioned as part of the MkV 40 MeV electron accelerator facility at the University of Hawaii.
* Renate Chasman and G. Kenneth Green "Preliminary Design of a Dedicated Synchrotron Radiation Facility", IEEE Transactions on Nuclear Science, NS22(3):1765-1767, June 1975

WEPWA073

Compton Scattering Gamma-ray Light Source Modeling and Optimization

radiation, brightness, laser, photon

2283

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
In Compton scattering light sources, a short (ps to ns) laser pulse and a high brightness relativistic electron beam collide to yield tunable, monochromatic, polarized gamma-ray photons. The properties of the gamma-ray phase space is studied, in relation to the full electron bunch and laser pulse phase spaces, along with collimation, nonlinear effects and other sources of spectral broadening. This process has potential high impact applications in homeland security, nuclear waste assay, medical imaging and stockpile surveillance, among other areas of interest. Detailed theoretical modeling is outlined to aid the design of Compton light sources and provide optimization strategies relevant within the context of nuclear photonics applications.

WEPWA075

High-gain X-ray FELs using a Transverse Gradient Undulator in an Ultimate Storage Ring

FEL, undulator, emittance, storage-ring

2286

Y.T. Ding, P. Baxevanis, Y. Cai, Z. Huang, R.D. Ruth
SLAC, Menlo Park, California, USA

An “ultimate” storage ring based on PEP tunnel has been designed to achieve diffraction limited emittance (at 1.5 Angstrom)[*]. With sufficient peak current, the beam brightness of such an “ultimate” storage ring may be sufficient to drive a short-wavelength, high-gain FEL. However, the large energy spread intrinsic to storage rings hinders the FEL applications for x-ray wavelengths. To overcome this problem, we adopt the transverse-gradient undulator concept[**][***] to study a high-gain FEL in an ultimate storage ring. Using PEP-X as an example, we showed from simulations that a high-gain FEL at the photon energy 1keV with a peak power of a few hundred megawatts can be achieved within a saturation length of 100 meters.
* Y. Cai et al., Phys. Rev. ST Accel. Beams 15, 054002 (2012).
** T. Smith et al., J. Appl. Phys. 50, 4580 (1979)
*** Z. Huang, Y. Ding and C. B. Schroeder, Phys. Rev. Lett 109, 204801 (2012).

WEPWA077

Aperture Test for Internal Target Operation in the JLAB High-current ERL

FEL, target, diagnostics, radiation

2289

S. Zhang, S.V. Benson, G.H. Biallas, K. Blackburn, J.R. Boyce, D.B. Bullard, J.L. Coleman, J. Delk, D. Douglas, P. Evtushenko, C.W. Gould, J.G. Gubeli, F.E. Hannon, D. Hardy, C. Hernandez-Garcia, K. Jordan, J.M. Klopf, R.A. Legg, M. Marchlik, W. Moore, G. Neil, J. Powers, T. Powers, D.W. Sexton, M.D. Shinn, C. Tennant, R.L. Walker, G.P. Williams, F.G. Wilson
JLAB, Newport News, Virginia, USA
J. Balewski, J. Bernauer, W. Bertozzi, R.F. Cowan, P.F. Fisher, E. Ihloff, A. Kelleher, R. Milner, L. Ou, B.A. Schmookler, c. Tschalär
MIT, Cambridge, Massachusetts, USA
N. Kalantarians
Hampton University, Hampton, Virginia, USA

Funding: Supported by the Commonwealth of Virginia, U.S. DOE Nuclear and High Energy Physics, and by the U.S. DOE Basic Energy Sciences under contract No. DE-AC05-060R23177.
A high current beam transmission test has been successfully completed at the JLAB FEL Facility, culminating in very low-loss transmission of a high current CW beam through a small aperture. The purpose of this test was to determine if an ERL is capable of meeting the stringent requirements imposed by the use of a 10¹⁸/cm³ internal gas target proposed for the DarkLight experiment*. Minimal beamline modifications were made to create a machine configuration that is substantially different from those used in routine UV or IR FEL operation. A sustained (8 hour) high power beam run was performed, with clean transmission through a 2 mm transverse aperture of 127 mm length simulating the target configuration. A beam size of 50 um (rms) was measured near the center of the aperture. Experimental data from a week-long test run consistently exhibited beam loss of only a few ppm on the aperture while running 4.5 mA current at 100 MeV – or nearly 0.5 MW beam power. This surpassed the users’ expectation and demonstrated a unique capability of an ERL for this type of experiments. This report presents a summary of the experiment, a brief overview of our activities, and outlines future plans.
References:
* P. Fisher, et al.,“Jlab PR-11-008: A Proposal for the DarkLight Experiment at the Jefferson Laboratory Free Electron Laser.” http://www.jlab.org/exp_prog/proposals/11prop.html

WEPWA078

Compact Accelerator Design for a Compton Light Source

cavity, gun, emittance, photon

2292

T. Satogata, K.E. Deitrick, J.R. Delayen, B.R.P. Gamage, K.G. Hernández-Chahín, C.S. Hopper, G.A. Krafft, R.G. Olave
ODU, Norfolk, Virginia, USA
K.G. Hernández-Chahín
DCI-UG, León, Mexico
G.A. Krafft, T. Satogata
JLAB, Newport News, Virginia, USA

Funding: Partially authored by Jefferson Science Associates, LLC under U.S. DOE contract NO. DE-AC05-06OR23177.
A compact electron accelerator suitable for Compton source applications is in design at the Center for Accelerator Science at Old Dominion University and Jefferson Lab. The design includes a KE=1.55 MeV low-emittance, optimized superconducting electron gun; a 23.45 MeV linac with multi-spoke 4.2 K superconducting cavities; and transport that combines magnetic longitudinal bunch compressor and transverse final focus. We report on the initial designs of each element, including end to end simulations with ASTRA and elegant, and expected beam parameters.

WEPWA091

Simulation Design of a Low Energy Bunch Compressor with Space Charge Effect

space-charge, gun, dipole, cathode

2307

A. He, Y. Hidaka, T.V. Shaftan, G.M. Wang, F.J. Willeke, L. Yang, L.-H. Yu
BNL, Upton, Long Island, New York, USA

Funding: Department of Energy, USA
Following the proposal of electron beam slicing method to generate short x-ray pulses in storage ring, we studied the feasibility of the crucial technique required by electron beam slicing, i.e., the generation of very low energy electron beam with very small beam size (30 μm) and very short bunch length (100 fs). Based on one of the BNL RF gun, 5 MeV beam energy and 50 pC bunch charge was assumed in the study. The beam ‘natural’ energy-time negative chirp, due to space charge effect, was used and the bunch length is compressed from from 0.8 ps to ~150 fs with a chicane structure. The system is in the space charge dominated regime. We use the code PARMELA and Generic optimization method for parameters optimization with various strategies to overcome the damaging from the space charge effect. After optimization, the beam transverse size is 50 micron and the bunch length is 150 fs, close to our original specification. In this paper we describe the design and the physical process in the compressor and focus section. The study confirmed the possibility to generate strong focused and compressed very low energy beam in the space charge dominated regime.

WEPWO007

Shape Optimization of a SRF Injector Cavity

emittance, cavity, solenoid, cathode

2322

J.K. Sekutowicz
DESY, Hamburg, Germany
W.C. Grabowski, R. Nietubyć, T. Wasiewicz
NCBJ, Świerk/Otwock, Poland

In this contribution we present studies on the shape optimization of 1.6-cell cavity with solenoid for a 1-mA class photo injector, meant as an electron source for FEL facilities. The main criterion for the optimization was the lowest slice emittance. Inclination angle of the cavity back wall, solenoid position and magnetic field, amplitude of the accelerating field, and emission phase were varied in these studies in order to find the minimum of slice emittance at the distance of 1 m from a photocathode, located in center of the cavity back wall

WEPWO011

In-vacuum Temperature Measurement of Niobium Components using Infrared Pyrometry during Electron Beam Welding Procedure

cavity, vacuum, controls, shielding

2334

L. Monaco, P. Michelato, C. Pagani, D. Sertore
INFN/LASA, Segrate (MI), Italy
V. Battista, G. Corniani, M. Festa
Ettore Zanon S.p.A., Schio, Italy

Electron beam welding (EBW) is widely used in the construction of Niobium Superconducting RF cavities. The welding sequence of such a complex structure, foresees many welding operations. The welding parameters depend on many variables as the material thickness, but also on the component temperature before each weld. This paper presents a technique to measure the temperature of Nb components in vacuum during the EBW operation using an IR pyrometer placed outside the vacuum chamber through an appropriate vacuum viewport. With the current configuration the system can measure temperatures up to 350°C in the vacuum conditions of the EBW vacuum chamber (10-5-10^-6 mbar). The technique was used to optimize the time interval between each subsequent equatorial weld operation during Nb cavities production at Ettore Zanon, increasing the welding procedure reliability and decreasing the waiting time by control of the temperatures in the weld region. Moreover this technique can be generally used for in vacuum measurements of components from room temperature up to about 350 °C. Future developments are under way to make this technique compatible with UHV and increasing the measurement range.

WEPWO015

Electron Beam Welding for High Gradient Superconducting Cavity

cavity, superconducting-cavity, linear-collider, collider

2346

T. Kubo, Y. Ajima, H. Hayano, H. Inoue, S. Kato, T. Saeki, M. Sawabe, K. Umemori, Y. Watanabe, S. Yamaguchi, M. Yamanaka
KEK, Ibaraki, Japan
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
T. Nagata
ULVAC, Inc., Tsukuba, Japan

Relations between electron beam welding parameters and appearances of weld beads are studied. It was found that a beam generator position and a welding direction affect a geometry of weld bead dramatically. Carbon including contaminants found after the chemistry are also commented.

WEPWO023

High Current Superconducting Cavity Study and Design

cavity, superconducting-cavity, linac, accelerating-gradient

2366

Z.C. Liu, J. Gao, S. Jin, Y. Liu, J.Y. Zhai, T.X. Zhao, H.J. Zheng
IHEP, Beijing, People's Republic of China
F. Wang
PKU, Beijing, People's Republic of China

Funding: Project 11275226 supported by NSFC
IHEP is developing a new type of high current superconducting cavity called slotted cavity proposed in 2010. The cavity is suitable for accelerating high beam current in Energy Recovery Linac (ERL). The cavity can extremely dump high order modes (HOMs) in the cavity to keep a high beam current threshold in the linac. We have studied and designed a three cell cavity and the fabrication is under going.

WEPWO029

Design of a SRF Quarter Wave Electron Gun at Peking University

cavity, gun, simulation, SRF

2378

P.L. Fan, K.X. Liu, S.W. Quan, F. Zhu
PKU, Beijing, People's Republic of China

Funding: Work supported by National Basic Research Project (No. 2011CB808302) and National Natural Science Funds (No. 11075007)
Superconducting RF electron guns hold out the promise of very bright beams for use in electron injectors, particularly in future high average power free-electron lasers (FELs) and energy recovery linacs (ERLs). Peking University is designing a new SRF gun which is composed of a quarter wave resonator (QWR) and an elliptical cavity. Comparing to the elliptical cavity, the QWR is sufficiently compact at the same frequency and its electric field is quasi-DC. We have finished the preliminary design of the QWR cavity. The simulation shows that multipacting is not a critical issue for our cavity structure. Beam dynamic simulation of the QWR cavity is also presented.
contact author : zhufeng7726@pku.edu.cn

WEPWO039

Prototyping of TEM-like Mode Resonators in the RAON

cavity, multipactoring, niobium, simulation

2384

H.C. Jung, M.O. Hyun, D. Jeon, H.J. Kim
IBS, Daejeon, Republic of Korea

Preliminary electric-magnetic designs of TEM-like mode resonators(a quarter wave resonator, a half wave resonator, two single spoke resonators) are accomplished for the superconducting linear accelerator in the RAON. Resonant cavities are numerically optimized using a CST MWS code to obtain higher E-field gradient along the beam line in conditions of the peak E-field and B-field is less than 30MV/m, 60mT respectively. Prototyping test of a quater wave resonator of optimum beta 0.047 using OFC(Oxygen Free Cupper)is in progress to analyze resonant frequency shifting by tolerances in fabrication process and external perturbations. It is compared with expected one using compuational codes.

WEPWO042

Dubna-Minsk SRF Technology Development Status Report

cavity, cryogenics, niobium, coupling

2393

N.S. Azaryan, Ju. Boudagov, D.L. Demin, V.V. Glagolev, G. Shirkov, G.V. Trubnikov
JINR, Dubna, Moscow Region, Russia
M.A. Baturitsky, N.M. Shumeiko
NC PHEP BSU, Minsk, Belarus
S.E. Demyanov, E.Yu. Kaniukov
Scientific-Practical Materials Research Centre of the National Academy of Sciences of Belarus, Minsk, Belarus
A. Ermakov, W. Singer, X. Singer
DESY, Hamburg, Germany
V.A. Karpovich, N.V. Liubetsky
BSU, Minsk, Belarus
S.V. Kolosov, A.A. Kurayev, A.O. Rak, A.K. Sinitsyn
Belarus State University of Informatics and Radioelectronics (BSUIR), Minsk, Belarus
S.I. Maximov, V.N. Rodionova
Belarussian State University, Scientific Research Institute of Nuclear Problems, Minsk, Belarus
A. Parshuto, V.S. Petrakovsky, I.L. Pobol, A.I. Pokrovsky, S.V. Yurevich, A.Yu. Zhuravsky
Physical-Technical Institute of the National Academy of Sciences of Belarus, Minsk, Belarus

In 2011 Dubna-Minsk collaboration started an activity on the development and manufacture the series of 1.3 GHz superconducting Nb cavities in the enterprises in Belarus. The current status of this work is presented in this report. Main EM characteristics of the cavity were calculated and the shop drawings for cavity fabrication were developed. Two test-benches were assembled for RF-tests of the cavities at room temperature and at liquid helium temperature. The measured SWR was about 1.01 due to special matching device developed for that. This measurement technique was applied to the single-cell cavity from FNAL at power level nearby 10 mW. Measured resonant frequency was about 1.27 GHz, while the measured Q-factor was 2.8·10⁴ at room temperature and more than 10⁸ at liquid helium temperature. To evaluate mechanical properties of sheet Nb and of model materials (Cu and Al), a number of tests were made. Series of half-cells were fabricated of Al to test the technique of hydraulic deep-drawing that will be used in production of Nb cavities. The modes for electron-beam welding of sheet Nb were explored and the first welding seams were tested. The method of chemical treatment of cavities was also elaborated.

Poster WEPWO042 [0.897 MB]

WEPWO049

A Proposal for an ERL Test Facility at CERN

cavity, linac, HOM, SRF

2414

R. Calaga, E. Jensen
CERN, Geneva, Switzerland

An energy recovery linac at 300-400 MeV is proposed as a test facility using a two-pass two-cryomodule concept as a proof of principle for a future ERL based electron-ion collider. This facility will enable both the development and validation of the required SRF technology performance and ERL specific beam dynamics essential for the future collider. Furthermore, the test facility can be used as the injector to the main linac in future. The test facility proposal, its potential uses and some aspects of the RF system are presented.

WEPWO050

Mechanical Study of 400 MHz Double Quarter Wave Crab Cavity for LHC Luminosity Upgrade

cavity, simulation, luminosity, vacuum

2417

B. P. Xiao, S.A. Belomestnykh, I. Ben-Zvi, J. Skaritka, Q. Wu
BNL, Upton, Long Island, New York, USA
L. Alberty Vieira, R. Calaga
CERN, Geneva, Switzerland
T.L. Grimm
Niowave, Inc., Lansing, Michigan, USA

A prototype double quarter wave crab cavity was designed for the Large Hadron Collider luminosity upgrade. A finite element model is used to simulate the mechanical properties of the crab cavity. The results are presented and a reinforcement concept is proposed to meet the safety requirements. The reinforcement components, as well as the cavity, are presently being fabricated at Niowave Inc.

WEPWO051

Manufacture of a Compact Prototype 4R Crab Cavity for HL-LHC

cavity, niobium, luminosity, vacuum

2420

G. Burt, B.D.S. Hall, C. Lingwood
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
L. Alberty Vieira, R. Calaga, O. Capatina
CERN, Geneva, Switzerland
C.H. Boulware, D. Gorelov, T.L. Grimm, C. Krizmanich, T.S. Lamie
Niowave, Inc., Lansing, Michigan, USA
C. Hill, P.A. McIntosh
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.A. Rimmer, H. Wang
JLAB, Newport News, Virginia, USA

Funding: This work has been funded by the EU through EUCARD and HiLumi and by STFC via the Cockcroft Institute.
A prototype compact SRF deflecting cavity has been manufactured for LHC. The base of the cavity has been machined out of large grain niobium ingot to allow the manufacture of the complex rod profile. Stiffening rods have been used to increase the mechanical strength of the outer can. Details of the cavity design and manufacture will be discussed.

WEPWO067

Conditions for the Existence of 1- and 2-point Multipactor in SRF Cavities

cavity, simulation, multipactoring, superconductivity

2456

V.D. Shemelin
CLASSE, Ithaca, New York, USA

Funding: NSF award DMR-0807731
One- and two-point multipactor (MP) in RF cavities are well-known phenomena. However, conditions when this or the other type of discharge develops were not clearly defined up to now. Here, an explicit description of these two types of the MP is presented, geometrical parameters, or figures of merit, responsible for initiation of the MP defined, and areas of their existence delineated. Small sizes of trajectories in the MP require a very precise calculation of fields for simulations. On the other hand, due to these small sizes, fields can be presented as the Taylor expansions and trajectories can be found solving ordinary differential equations of motion. Conditions of motion stability and influence of the Miller force are also accounted.

WEPWO077

Rf System Requirements for JLab’s MEIC Collider Ring

ion, cavity, impedance, SRF

2477

S. Wang, R. Li, R.A. Rimmer, H. Wang, Y. Zhang
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The Medium-energy Electron Ion Collider (MEIC), proposed by Jefferson Lab, consists of a series of accelerators [1]. At the top energy are the electron and ion collider rings. For the ion ring, it accelerates five long ion bunches to colliding energy and rebunches ions into a train of very short bunches before colliding. A set of low frequency RF system is needed for the long ion bunch energy ramping. Another set of high frequency RF cavities is needed to rebunch ions. For the electron ring, superconducting RF (SRF) cavities are needed to compensate the synchrotron radiation energy loss. The impedance of the SRF cavities must be low enough to keep the high current electron beam stable. The preliminary design requirements of these RF cavities are presented.
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.

WEPWO079

Superconducting Single-spoke Cavities for High-velocity Applications

cavity, multipole, higher-order-mode, linac

2480

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

Spoke cavities have been investigated for particle acceleration in the high-velocity regime. As part of these efforts, single-spoke cavities for particles traveling at the speed of light are being designed and built for proof-of-principle demonstration. We report here on the results of electromagnetic properties, design optimization, multipacting analysis, field non-linearities and higher order mode spectrum for a single-spoke cavity operating at 325 MHz.

WEPEA011

Bursting Patterns of Coherent Synchrotron Radiation in the ANKA Storage Ring

impedance, radiation, simulation, synchrotron

2516

M. Schwarz, V. Judin, A.-S. Müller
KIT, Karlsruhe, Germany
M. Klein
SOLEIL, Gif-sur-Yvette, France

We report measurements of bursting patterns of coherent synchrotron radiation (CSR) for a wide range of single bunch currents at the ANKA storage ring. The radiation was detected with a fast THz detector, a Hot Electron Bolometer, and its signal acquired with both a spectrum analyzer and an external sampling oscilloscope. Both analysis methods consistently show the onset of bursting at a threshold current with the appearance of strong high frequency bands with higher harmonics in the several 10th of kHz range. For currents higher than twice the threshold value an abrupt change in the bursting pattern occurs. These results are compared with different numerical models solving the one-dimensional Vlasov-Fokker-Planck equation.

WEPEA013

Electron Cloud Studies for the Upgrade of the CERN PS

extraction, simulation, synchrotron, proton

2522

G. Iadarola
Naples University Federico II, Science and Technology Pole, Napoli, Italy
H. Damerau, S.S. Gilardoni, G. Iadarola, S. Rioja Fuentelsaz, G. Rumolo, G. Sterbini, C. Yin Vallgren
CERN, Geneva, Switzerland
M.T.F. Pivi
SLAC, Menlo Park, California, USA

The observation of a significant dynamic pressure rise as well as measurements with dedicated detectors indicate that an electron cloud develops in the CERN PS during the last stages of the RF manipulations for the production of LHC type beams, especially with 25ns bunch spacing. Although presently these beams are not degraded by the interaction with the electron cloud, which develops only during few milliseconds before extraction, the question if this effect could degrade the future high intensity and high brightness beams foreseen by the LHC Injectors Upgrade (LIU) project is still open. Therefore several studies are being carried out employing both simulations and measurements with the electron cloud detectors in the machine. The aim is to develop a reliable electron cloud model of the PS vacuum chambers in order to identify possible future limitations and find suitable countermeasures.

WEPEA014

Recent Electron Cloud Studies in the SPS

injection, emittance, simulation, vacuum

2525

G. Iadarola, H. Bartosik, M. Driss Mensi, H. Neupert, G. Rumolo, M. Taborelli
CERN, Geneva, Switzerland
G. Iadarola
Naples University Federico II, Science and Technology Pole, Napoli, Italy

It is important to qualify the present status of the SPS with respect to the electron cloud before the Long Shutdown of the CERN accelerator complex, which will take place in 2013-2014. Therefore several electron cloud studies were performed during the 2012 run in order to get a full characterization of the behavior of the SPS with the LHC-type beams with 25 ns bunch spacing, which can be very sensitive to electron cloud effects. The collected information should allow to understand up to which extent this long period without beam operation - and the related interventions on the machine - will degrade the present conditioning state of the SPS, which has been achieved by “scrubbing” over several years. Several measurements with different beam conditions have been collected also on the electron cloud detectors installed in the machine. These results, in combination with detailed simulation studies, will provide the basis for defining strategies of electron cloud mitigation as required for the production of future high intensity and high brightness beams within the LHC Injectors Upgrade (LIU) project.

WEPEA042

The PS Upgrade Programme: Recent Advances

injection, emittance, resonance, extraction

2594

S.S. Gilardoni, S. Bart Pedersen, C. Bertone, N. Biancacci, A. Blas, D. Bodart, J. Borburgh, P. Chiggiato, H. Damerau, S. Damjanovic, J.D. Devine, T. Dobers, M. Gourber-Pace, S. Hancock, A. Huschauer, G. Iadarola, L.A. Lopez Hernandez, A. Masi, S. Mataguez, E. Métral, M.M. Paoluzzi, S. Persichelli, S. Pittet, S. Roesler, C. Rossi, G. Rumolo, B. Salvant, R. Steerenberg, G. Sterbini, L. Ventura, J. Vollaire, R. Wasef, C. Yin Vallgren
CERN, Geneva, Switzerland
M. Migliorati
University of Rome "La Sapienza", Rome, Italy

The LHC Injectors Upgrade project (LIU) has been initiated to improve the performances of the existing injector complex at CERN to match the future requirements of the HL-LHC. In this framework, the Proton Synchrotron (PS) will undergo fundamental changes for many of its main systems: the injection energy will be increased to reduce space-charge effects, the transverse damper will be improved to cope with transverse instabilities the RF systems will be upgraded to accelerate higher beam intensity and brightness. These hardware improvements are triggered by a series of studies meant to identify the most critical performance bottlenecks, like space charge, impedances, longitudinal and transverse instabilities, as well as electron-cloud. Additionally, alternative production schemes for the LHC-type beams have been proposed and implemented to circumvent some of the present limitations. A summary of the most recent advances of the studies, as well as the proposed hardware improvements is given.

WEPEA053

Progress with the Upgrade of the SPS for the HL-LHC Era

kicker, extraction, simulation, emittance

2624

B. Goddard, T. Argyropoulos, W. Bartmann, H. Bartosik, T. Bohl, F. Caspers, K. Cornelis, H. Damerau, L.N. Drøsdal, L. Ducimetière, J. Esteban Müller, R. Garoby, M. Gourber-Pace, W. Höfle, G. Iadarola, L.K. Jensen, V. Kain, R. Losito, M. Meddahi, A. Mereghetti, V. Mertens, O. Mete, E. Montesinos, Y. Papaphilippou, G. Rumolo, B. Salvant, E.N. Shaposhnikova, M. Taborelli, H. Timko, F.M. Velotti
CERN, Geneva, Switzerland
E. Gianfelice-Wendt
Fermilab, Batavia, USA

The demanding beam performance requirements of the HL-LHC project translate into a set of requirements and upgrade paths for the LHC injector complex. In this paper the performance requirements for the SPS and the known limitations are reviewed in the light of the 2012 operational experience. The various SPS upgrades in progress and still under consideration are described, in addition to the machine studies and simulations performed in 2012. The expected machine performance reach is estimated on the basis of the present knowledge, and the remaining decisions that still need to be made concerning upgrade options are detailed.

WEPEA062

Progress in ELENA Design

extraction, emittance, vacuum, antiproton

2651

S. Maury, W. Bartmann, P. Belochitskii, H. Breuker, F. Butin, C. Carli, T. Eriksson, R. Kersevan, S. Pasinelli, G. Tranquille, G. Vanbavinckhove
CERN, Geneva, Switzerland
W. Oelert
FZJ, Jülich, Germany

The Extra Low Energy Antiproton ring (ELENA) is a small ring at CERN which will be built to increase substantially the number of usable (or trappable) antiprotons delivered to experiments for studies with antihydrogen. The report shows the progress in the ELENA design. The choice of optics and ring layout inside of AD hall is given. The main limitations for beam parameters at extraction like intra beam scattering and tune shift due to space charge are discussed. The electron cooler plays key role in ELENA both for efficient deceleration as well as for preparing extracted beam with parameters defined by experiments. The other important systems like beam vacuum, beam instrumentations and others are reviewed as well.

WEPEA063

Upgrades and Consolidation of the CERN AD for Operation during the Next Decades

controls, target, antiproton, vacuum

2654

T. Eriksson, M. E. Angoletta, L. Arnaudon, J.A. Baillie, M. Calviani, F. Caspers, L.V. Joergensen, R. Kersevan, G. Le Godec, R. Louwerse, M. Ludwig, S. Maury, A. Newborough, C. Oliveira, G. Tranquille
CERN, Geneva, Switzerland

As the ELENA project is now well underway, focus is turned to the Antiproton Decelerator (AD) itself. Most of the machine’s key components are in operation since more than 25 years and a substantial consolidation program is now being launched in view of continued operation beyond 2025. Over the course of the next few years a progressive consolidation of the AD-Target area, the AD-ring and all associated systems will take place. Several investigations have recently been performed in the target area with the objective of establishing the radiation environment and the sensitivity of the antiproton production to potential misalignment of the production elements. Identification of reliability and serviceability issues of the AD-ring components and associated systems has been done and will continue during the 2013 shut-down. Planned and ongoing consolidation activities are also discussed with emphasis on stochastic and electron beam cooling, instrumentation, RF systems, vacuum, magnets, power converters and beam transfer equipment.

WEPEA074

Optimisation of the Beam Line for COMET Phase-I

dipole, solenoid, background, target

2681

A. Kurup, I. Puri, Y. Uchida, Y. Yap
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
R. Appleby, S.C. Tygier
UMAN, Manchester, United Kingdom
R.T.P. D'Arcy, A. Edmonds, M. Lancaster, M. Wing
UCL, London, United Kingdom

The COMET experiment will search for very rare muon processes that will give us an insight into particle physics beyond the Standard Model. COMET requires an intense beam of muons with a momentum less than 70 MeV/c. This is achieved using an 8 GeV proton beam; a heavy metal target to primarily produce pions; a solenoid capture system; and a curved solenoid to perform charge and momentum selection. It was recently proposed to build COMET is two phases with physics measurements being made in both phases. This requires re-optimising the beam line for a shorter curved solenoid. This will affect the pion and muon yield; the momentum distributions at the detector; and the collimator scheme required. This paper will present the beam line design for COMET Phase-I, which aims to maximise the yield for low momentum muons suppressing sources of backgrounds in the beam.

WEPEA075

Large Emittance Beam Measurements for COMET Phase-I

solenoid, simulation, proton, background

2684

A. Kurup, I. Puri, Y. Uchida, Y. Yap
Imperial College of Science and Technology, Department of Physics, London, United Kingdom
R. Appleby, S.C. Tygier
UMAN, Manchester, United Kingdom
R.T.P. D'Arcy, A. Edmonds, M. Lancaster, M. Wing
UCL, London, United Kingdom

The COMET experiment will search for very rare muon processes that will give us an insight into particle physics beyond the Standard Model. COMET requires an intense beam of muons with a momentum less than 70 MeV/c. This is achieved using an 8 GeV proton beam; a heavy metal target to primarily produce pions; a solenoid capture system; and a curved solenoid to perform charge and momentum selection. Understanding the pion production yield and transport properties of the beam line is an important part of the experiment. The beam line is a continuous solenoid channel, so it is only possible to place a beam diagnostic device at the end of the beam line. Building COMET in two phases provides the opportunity to investigate the pion production yield and to measure the transport properties of the beam line in Phase-I. This paper will demonstrate how this will be done using the experimental set up for COMET Phase-I.

WEPFI003

A New Timing System and Electron Gun Modulator

gun, linac, synchrotron, simulation

2705

A.S. Setty, A.S. Chauchat, D. Fasse, D. Jousse
Thales Communications & Security (TCS), Gennevilliers Cedex, France

In the last decade, Thales Communications & Security has manufactured turnkey linacs for the SOLEIL, ALBA and BESSY II synchrotrons. In the meanwhile, a new timing system and electron gun modulator was designed and a gun pulse length of 600 ps was measured. This paper will describe the system and will present the beam dynamics simulations results, comparing them with those obtained with the previous gun modulator *.
* A. Setty, "Beam dynamics of the 100 MeV preinjector for the Spanish synchrotron ALBA", PAC07, Albuquerque, USA, June 2007.

WEPFI015

Design and Field Measurements of a Linear Accelerator Endowed with Single Feed with Movable Short Coupler

emittance, linac, dipole, simulation

2732

M. Dal Forno, R. Vescovo
University of Trieste, Trieste, Italy
P. Craievich, M. Dal Forno, G. Penco
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
P. Craievich
PSI, Villigen PSI, Switzerland

The free electron laser performances strongly depend on the beam quality. The dipolar field present in the linac coupler causes the beam emittance degradation. This paper studies an alternative solution for reducing the dipolar field, by using a symmetrical coupler with single feed input and a movable short circuit placed on the opposite waveguide. The structure has been simulated and optimized with the Ansys HFSS simulation code. An aluminum prototype has been machined in the workshop of “Elettra - Sincrotrone Trieste S.C.p.A.”. After matching and tuning the accelerating structure, the phase advance and the coupler field asymmetries have been measured by means of the bead-pull method and have been compared with the simulation results.

WEPFI023

Study on Two-cell RF-deflector Cavity for Ultra-short Electron Bunch Measurement

cavity, gun, simulation, target

2753

Y. Nishimura, K. Sakaue, T. Takahashi, M. Washio
Waseda University, Tokyo, Japan
T. Takatomi, J. Urakawa
KEK, Ibaraki, Japan

Funding: Work supported by JSPS Grant-in-Aid for Scientific Research (A) 10001690 and the Quantum Beam Technology Program of MEXT.
We have been developing an S-band Cs-Te photocathode rf electron gun system for pulse radiolysis and laser Compton scattering experiment at Waseda University. These researches demand for high quality and well controlled electron beam. In order to measure the ultra-short electron bunch, we decided to use rf-deflector cavity, which can convert the longitudinal distribution to that of transverse. With this technique, the longitudinal bunch profile can be obtained as the transverse profile. We used the 3D electromagnetic simulation codes HFSS for designing rf deflector cavity and GPT for beam tracking. The cavity has 2 cell structures operating on π mode, standing wave, dipole (TM120) mode at 2856MHz. We have confirmed on HFSS that 2 cell rf-deflector cavity can produce 660G magnetic field per cell on beam line with 750kW input rf power. This field strength is enough for our target, which is 100fs bunch length measurement at 4.3MeV. In this conference, we will present the cavity structure design, the present progresses and future plan.

WEPFI030

Design Studies on NSC KIPT Electron Gun System

gun, high-voltage, cathode, power-supply

2768

Z.S. Zhou, Y.L. Chi, D.Y. He
IHEP, Beijing, People's Republic of China

In NSC KIPT, a neutron source based on a subcritical assembly driven by a 100MeV/100kW electron linear accelerator is under design and development. The linear accelerator needs a new high current electron gun. In this paper, physical design, mechanical fabrication and beam test of this new electron gun are described. The emission current is designed to be higher than 2A for the pulse width of 3us with repetition rate of 50 Hz. The gun will operate with a DC high voltage power supply which can provide up to 150 kV high voltages. Computer simulations and optimizations have been carried out in the design stage, including the gun geometry and beam transport line. The test results of high voltage conditioning and beam test are presented. The operation status of the electron gun system is also included. The basic test results show that the design, manufacture and operation of the new electron system are basically successful.

WEPFI036

R&D on a Main Accelerating Section of a Compact THz-FEL

laser, FEL, simulation, radiation

2780

W. Bai, M. Li, X. Shen, H. Wang, X. Yang
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

In order to develop a tera-hertz(THz) radiation source and to make scientific researches on application of THz technology, a study on tera-hertz source is performed. The radiation source is based on technology of free electron laser(FEL). The energy booster section of the injector uses a 9 Cell standing wave accelerator as the main accelerator for the FEL. The accelerator works at S band.(2856 MHz), excited by a microwave power of about 3.5 MW. At the end of the accelerator, the high quality beam energy is of 6.5MeV ~ 7 MeV, and the current about 300 mA. This paper presents the newly prgress of the , as well as the working condition of the main accelerator.

WEPFI037

Recent Status of a C-band 2MeV Accelerator

target, laser, linac, status

2783

W. Bai
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

In order to carry out engineering research on miniaturization of accelerator, we performs effort to develop C-band 2MeV standing wave accelerator. At present , the important progress has been achieved on the accelerator development. The accelerating tube has been fully sealed, and the hot test platform of the accelerator has been built. In condition of repetition rate of 200Hz, preliminary power test has been got through. Using ionization chamber dose monitor, we tested the dose rate of X-ray at 1m before the target. And by means of steel absorption method, we tested the energy of the electron beam. The preliminary test results are: beam energy about 2.0MeV, dose rate about 2Gy/min•m.

WEPFI039

New X-band Deflecting Cavity Design for Ultra-short Bunch Length Measure of FEL at SINAP

cavity, simulation, impedance, FEL

2788

J.H. Tan, W. Fang, Q. Gu, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

For the development of Free Electron Lasers (FEL) at SINAP, ultra-short bunch is the crucial requirement for excellent lasing performance. It’s big challenge for deflecting cavity to measure the length of ultra-short bunch, and higher deflecting gradient is required for higher measurement resolution. X-band travelling wave deflecting structure has features of higher deflecting voltage and compact structure, which is good performance at ultra-short bunch length measuring. In this paper, a new X-band deflecting structure was designed, operated at HEM11- 2π/3 mode. For suppressing the polarization of deflection plane of the HEM11 mode, two symmetrical caves are added on the cavity wall to separate two polarized modes. More details of design and simulation results are presented in this paper.

WEPFI045

PAL-XFEL Accelerating Structures

linac, klystron, emittance, impedance

2806

H.-S. Lee, H. Heo, J.Y. Huang, W.H. Hwang, S.D. Jang, Y.D. Joo, H.-S. Kang, I.S. Ko, S.S. Park, Y.J. Park
PAL, Pohang, Kyungbuk, Republic of Korea
I.S. Ko
POSTECH, Pohang, Kyungbuk, Republic of Korea
H. Matsumoto
KEK, Ibaraki, Japan
S.J. Noh, K.M. Oh
Vitzrotech Co., Ltd., Ansan City, Kyunggi-Do, Republic of Korea

We need 172 accelerating structures for the PAL-XFEL 10 GeV main linac. It takes long time for these structures to be delivered. So we are trying to find suppliers of the accelerating structures. First, we made an order of 40 accelerating structures to Mitsubishi Heavy Industry (MHI), which have Quasi-type couplers to reduce the quadruple and sextuple components of the electric field in the coupling cavity. And Research Instruments (RI) has fabricated a 3m long race type accelerating structure for PAL-XFEL. Also, Vitzrotech which is a domestic company and IHEP in China are under developing accelerating structures for PAL-XFEL respectively. We will describe the current status of accelerating structures and high power test results of the newly developed structures in this paper.

WEPFI065

The Commissioning of the EBTF S-band Photoinjector Gun at Daresbury Laboratory

cavity, klystron, vacuum, laser

2845

A.E. Wheelhouse, R.K. Buckley, S.R. Buckley, P.A. Corlett, J.W. McKenzie, B.L. Militsyn, A.J. Moss
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

The first stage of the installation of the Electron Beam Test Facility (EBTF) at Daresbury Laboratory has been completed and a commissioning phase is presently underway. At the heart of the machine is a photoinjector based on a two and a half cell S-band RF gun incorporating a metallic photocathode, which is capable of delivering 4-6 MeV, low emittance, short electron pulses (10 - 250 pC). The photoinjector is driven by a UV light at 266 nm wavelength delivered by a laser system and is powered by a RF system incorporating a Low Level RF system, a high power RF modulator and a klystron. This paper describes the commissioning and conditioning of the photoinjector.

WEPFI082

Double-tip Magnetic Field Enhancement

simulation, cavity, vacuum, cathode

2887

F.Y. Wang, L. Xiao
SLAC, Menlo Park, California, USA

The local electric field enhancement factor β in an rf accelerator cavity has been studied experimentally for decades and found to be in the range from few tens up to few hundreds for various rf frequencies and materials. A large field enhancement factor is usually thought to come from sharp tips whose β is roughly the ratio of their height to their tip radius. For a β of few hundred, the corresponding tip height would need to be more than 10 microns, which should be visible in a scanning electron microscope (SEM). However, the estimated β from SEM images of cavity surfaces is around 10. Therefore, the physics of such large β values is still not clear. In this paper, we have studied differentμstructures and found that the magnetic field could be enhanced many times in the presence of two nearby tips with β of 10. The large local magnetic field enhancement could lead to large enhanced pulsed heating and thus could melt surface in a very short time and form a liquid Taylor cone.

WEPFI083

High Power Tests of the 2-Pin Waveguide Structures

factory, linear-collider, collider, site

2890

F.Y. Wang, Z. Li
SLAC, Menlo Park, California, USA

An X-band Two-Pin Waveguide Structure has been designed to study the influence of power flow on rf breakdown. Three different sets of pins will be tested at SLAC. These sets were designed to achieve a similar peak surface electric field on one of the pins for input rf power levels that vary by about an order of magnitude (the other pin is used for matching). Two sets of pins have been tested so far, and the breakdown rate was found to be strongly dependent on the power flow. In this paper, we review the experimental setup, the complete set of results and their implications.

WEPFI085

Source and Extraction for Simultaneous Four-hall Beam Delivery System at CEBAF

laser, cavity, extraction, cathode

2896

R. Kazimi, J. Hansknecht, M. Spata, H. Wang
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
A new design for simultaneous delivery of the electron beam to all four 12 GeV CEBAF experimental halls* requires a new 750 MHz RF separator system in the 5th pass extraction region, a 250 MHz repetition rate for its beams, and addition of a fourth laser at the photo-cathode gun. The proposed system works in tandem with the existing 500 MHz RF separators and beam repetition rate on the lower passes. The new 5th pass RF separators will have the same basic design but modified to run at 750 MHz. The change to the beam repetition rate will be at the photo-cathode gun through an innovative upgrade of the seed laser driver system using electro-optic modulators. The new laser system also allows addition of the fourth laser. The new RF separators, the new laser system and other hardware changes required to implement the Four-Hall operation delivery system will be discussed in this paper.
* Simultaneous Four-Hall Operation for 12 GeV CEBAF, Proceedings of this conference.

WEPFI086

Normal Conducting Radio Frequency X-band Deflecting Cavity Fabrication, Validation and Tuning

cavity, vacuum, linear-collider, collider

2899

R.B. Agustsson, L. Faillace, A.Y. Murokh, E. Spranza, S. Storms
RadiaBeam, Santa Monica, USA
D. Alesini
INFN/LNF, Frascati (Roma), Italy
V.A. Dolgashev, J.R. Lewandowski
SLAC, Menlo Park, California, USA
J.B. Rosenzweig
UCLA, Los Angeles, California, USA
V. Yakimenko
BNL, Upton, Long Island, New York, USA

An X-band Traveling wave Deflector mode cavity (XTD) has been developed, fabricated, tuned and characterized by Radiabeam Technologies to perform longitudinal measurement of the sub-picosecond ultra-relativistic electron beams. The device is optimized for the 100 MeV electron beam parameters at the Accelerator Test Facility (ATF) at Brookhaven National Laboratory, and is scalable to higher energies. The XTD is designed to operate at 11.424 GHz, and features short filling time, femtosecond resolution, and a small footprint. RF design, structure fabrication, cold testing and tuning results are presented.

WEPFI092

Multipacting Simulation of the MICE 201 MHz RF Cavity

cavity, solenoid, simulation, coupling

2914

T.H. Luo, D.J. Summers
UMiss, University, Mississippi, USA
D.L. Bowring, A.J. DeMello, D. Li, P. Pan, S.P. Virostek
LBNL, Berkeley, California, USA
L. Ge
SLAC, Menlo Park, California, USA

The international Muon Ionization Cooling Experiment (MICE) aims to demonstrate transverse cooling of muon beams by ionization. The MICE ionization cooling channel requires eight 201-MHz normal conducting RF cavities to compensate for the longitudinal beam energy loss in the cooling channel. Multipacting is a resonant electron discharge produced by the synchronization of emitted electrons with the RF fields, which can cause breakdown at high power RF operation. In this paper, we present the study of the multipacting effect in the MICE 201 MHz cavities with the SLAC ACE3P code. The simulation is carried out in the cavity body, the RF coupler region, and the coaxial waveguide, with the external magnetic field from the Coupling Coil. We will identify potential RF breakdowns due to multipacting and propose a solution to suppress them.

WEPME001

SOLEIL Beam Stability Status

feedback, coupling, emittance, undulator

2917

N. Hubert, L. Cassinari, J.-C. Denard, M. Labat, J.-F. Lamarre, A. Nadji, L.S. Nadolski, D. Pédeau, M.-A. Tordeux
SOLEIL, Gif-sur-Yvette, France

This paper reports recent work for improving SOLEIL electron beam stability. X-BPMs from four bending magnet beamline frontends have been inserted in the global orbit feedback loops during user operation. The corresponding source point stabilities have improved and results are reported. Some of the new beamlines request more stringent stability than the existing ones. Their requirements are not only tighter for beam orbit but also for beam size and divergence stability. For these reasons, SOLEIL has decided to define beam quality criteria for each sensitive beamline. Then it can predict ahead of commissioning how well the beamline will likely perform. A feedback on the vertical emittance, measured by a pinhole camera, has been introduced in order to reduce beam size and divergence variations due to magnetic configuration changes of a few insertion devices.

WEPME006

Optical Synchronization and Electron Bunch Diagnostic at ELBE

laser, pick-up, feedback, wakefield

2932

M. Kuntzsch, M. Gensch, U. Lehnert, F. Röser, R. Schurig
HZDR, Dresden, Germany
M. Bousonville, M.K. Czwalinna, H. Schlarb, S. Schulz, S. Vilcins
DESY, Hamburg, Germany

The continuous wave electron accelerator ELBE is upgraded to generate short and highly charged electron bunches (~200fs duration, up to 1 nC) . In the last years a prototype of an optical synchronization system using a mode locked fiber laser has been build up at ELBE which is now in commissioning phase. The stabilized pulse train can be used for new methods of electron bunch diagnostics like bunch arrival time measurements with the potential of femtosecond resolution. At ELBE a bunch arrival time monitor (BAM) has been designed and tested at the accelerator. The contribution will show the design of the BAM and first measurement results at the ELBE accelerator.

WEPME008

Precision LLRF Controls for the S-Band Accelerator REGAE

laser, gun, LLRF, controls

2938

M. Hoffmann, H. Kay, U. Mavrič, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany
W. Jałmużna, T. Kozak, A. Piotrowski
TUL-DMCS, Łódź, Poland

The linear accelerator REGAE (Relativistic Electron Gun for Atomic Exploration) at DESY delivers electron bunches with a few femtosecond duration for time-resolved experiments of material structure in pump-probe configuration. To achieve the desired 10 fs resolution, the Low Level RF controls for the normal conducting S-band cavities must provide field stability of 0.01% in amplitude and of 0.01deg in phase. To achieve these demanding stability a recently developed LLRF controller based on the Micro-Telecommunications Computing Architecture (MTCA.4) have been installed and commission. In this paper, we report on measurement performance of the LLRF system, the achieved stability and current limitations.

WEPME017

Development and Application of the Trigger Timing Watchdog System in KEK Electron/Positron Linac

linac, controls, klystron, EPICS

2962

M. Satoh, K. Furukawa, F. Miyahara, T. Suwada
KEK, Ibaraki, Japan
T. Kudou, S. Kusano
Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan

The KEK injector linac provides electrons and positrons to several accelerator facilities. A 50 Hz beam-mode switching system has been constructed to realize simultaneous top-up injections for Photon Factory and the KEKB high- and low-energy rings, which require different beam characteristics. An event-based timing and control system was built to change the parameters of various accelerator components within 20 ms. The components are spread over a 600-m-long linac and require changes to a total of 100 timing and control parameters. The system has been operated successfully since the autumn of 2008 and has been improved upon as beam operation experience has been accumulated. The timing watchdog and alert system are indispensable for the stable and high quality beam operation. For this purpose, we developed and utilized several timing watchdog system. We will present the detail of timing signal watchdog system for the KEK injector linac.

WEPME019

Development of Beam Position Feedback Control System in KU-FEL

FEL, feedback, gun, controls

2968

H. Ohgaki, Y.W. Choi, H. Imon, T. Kii, R. Kinjo, T. Konstantin, K. Masuda, H. Negm, K. Okumura, M. Omer, S. Shibata, K. Shimahashi, K. Yoshida, H. Zen
Kyoto University, Institute for Advanced Energy, Kyoto, Japan

The stability of electron beam parameters such as position, energy etc. is very crucial for stable FEL operation. In Kyoto University MIR-FEL facility (KU-FEL), fluctuation of beam position and energy is caused by external fluctuations, such as the fluctuation in the cathode temperature of the thermionic RF-gun due to the back-streaming electrons, fluctuation of RF phase and amplitude, fluctuations of room and water temperatures, electric noises and so on. To monitor electron beam movement, we have already developed BPM system consisting of a 4-button electrode type BPM, a heterodyne detector, and CAMAC ADC in KU-FEL. By using this BPM system we have observed some correlations between external fluctuations and the beam position movements. In this conference, we will present the developed BPM system as well as the beam feedback system for stable KU-FEL operation.

WEPME038

Slow Orbit Feedback and Beam Stability at ALBA

photon, injection, wiggler, feedback

3010

J. Marcos, M. Muñoz
CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain

ALBA is a 3GeV 3rd generation synchrotron radiation source built nearby Barcelona providing service to users since May 2012. During all this period, a Slow Orbit Feedback system (SOFB) has been running during users’ operation in order to deliver a stable photon beam to the Beamlines. The system employs 88 out of the 10⁴ Beam Position Monitors (BPMs) available at ALBA and 88 horizontal and vertical correctors. In addition, since the middle of the year (July 2012), the reading of the X-Ray BPM (XBPM) for one of the Front Ends, with a Bending Magnet as a source, has also been included in the correction loop. In this paper we summarize the performance of the SOFB system. Besides, we also present data corresponding to the evolution along the year of the XBPM readings for several Front Ends that have a planar Insertion Device (ID) as a source. The analyzed XBPMs are not included in the orbit correction loop, and consequently they supply information regarding the long term stability of ALBA Storage Ring.

WEPME042

Modelling and Studies for a Wideband Feedback System for Mitigation of Transverse Single Bunch Instabilities

feedback, kicker, pick-up, injection

3019

K.S.B. Li, W. Höfle, G. Rumolo
CERN, Geneva, Switzerland
J.M. Cesaratto, J.E. Dusatko, J.D. Fox, M.T.F. Pivi, K.M. Pollock, C.H. Rivetta, O. Turgut
SLAC, Menlo Park, California, USA

As part of the LHC injector upgrade a wideband feedback system is under study for mitigation of coherent single bunch instabilities. This type of system may provide a generic way of shifting the instability threshold to regions that are currently inaccessible, thus, boosting the brightness of future beams. To study the effectiveness of such systems, a numerical model has been developed that constitutes a realistic feedback system including real transfer functions for pickup and kicker, realistic N-tap FIR and IIR filters as well as noise and saturation effects. Simulations of SPS cases have been performed with HeadTail to evaluate the feedback effectiveness in the presence of electron clouds and TMCI. Some results are presented addressing bandwidth limitations, noise issues and amplifier power requirements.

WEPME049

An Application of Laser Position Sensing Detector for Magnet Centralizing System

quadrupole, laser, alignment, dipole

3040

C.-S. Lin, J.-R. Chen, M.L. Chen, P.S.D. Chuang, H.C. Ho, K.H. Hsu, D.-G. Huang, C.K. Kuan, W.Y. Lai, C.J. Lin, H.C. Lin, H.M. Luo, S.Y. Perng, P.L. Sung, T.C. Tseng, H.S. Wang, M.H. Wu
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

Taiwan Photon Source (TPS) project has been proposed to create a 3GeV synchrotron light source. The designated ultra-low emittance of this new light source requires high precision positioning of storage ring magnets. The alignment of all magnets is very importance since it directly affects the closed orbit of electron beams. Previously, conventional on-site alignment of the magnets was mainly relying on the theodolite performance. The cumulated errors could be in the order of 0.1mm. In this paper, a new alignment scheme is proposed to enhance the on-site alignment of magnets for TPS project. To achieve the high precision requirements, a device possessing the advantages of expansion mandrel in conjunction with Position Sensing Detector (PSD) is proposed. The development of this alignment device is anticipated to provide a better mechanism to properly align the centers of the both quadrupole and sextupole magnets on girder with less than 30μm positioning errors.

THOAB103

Phase Space Tomography Research at Daresbury

quadrupole, space-charge, simulation, FEL

3096

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

We report on the progress of phase space tomography research at Daresbury. The efforts over the past three years have been focussed on measuring the electron beam at the ALICE tomography section. Based on this result, we have developed techniques for improving resolution using normalised phase space, removing streaking artefacts by thresholding, demonstrating reliability of reconstructed phase space. We have developed in-house reconstruction codes using both the Filtered Back Projection and the Maximum Entropy Techniques. We are currently using a combination of simulation and measurements to investigate the onset of space charge effects at low bunch charges over short distances.

Slides THOAB103 [0.878 MB]

THOBB103

THz Electron-pulse-train Dynamics in a MeV Photo-injector

acceleration, cathode, bunching, laser

3109

F.H. Chao, C.H. Chen, Y.-C. Huang
NTHU, Hsinchu, Taiwan
P.J. Chou
NSRRC, Hsinchu, Taiwan

A conventional free electron laser (FEL) is bulky and expensive. In order to quickly build up the FEL power in a short undulator, a laser technology has been proposed to generate a pre-bunched electron pulse-train with a THz bunching frequency from a photoinjector*. The bunching factor** of an accelerated pulse-train beam is influenced by the beam radius, initial bunching frequency, space charge force, acceleration gradient, and acceleration phase in an accelerator. For a given RF accelerator and initial beam parameters, there is a limitation on the maximally attainable bunching factor and bunching frequency for the accelerated pulse-train beam. This paper presents a theoretical analysis for the bunching factor and bunching frequency of an accelerated pulse-train beam subject to nominal initial beam conditions in a photoinjector. The theoretical analysis is compared with the simulation results from the simulation code, PARMELA. To obtain an output bunching factor larger than 0.5%, our simulation study indicates that the maximum bunching frequency at the cathode is 25 THz for a 150 A beam current under a peak acceleration field of 80 MV/m.
* Y.C. Huang, C.H. Chen, A.P. Lee, W.K. Lau, S.G. Liu, NIM, A, 637, S1–S6 (2011).
** Y.C Huang, Appl. Phys. Lett., 96, 231503 (2010).

Slides THOBB103 [3.076 MB]

THOAB203

100 MeV/100kW Electron Linear Accelerator Driver of the NSC KIPT Neutron Source

target, neutron, gun, bunching

3121

A.Y. Zelinsky, N. Ayzatsky, O. Bezditko, I.M. Karnaukhov, V.A. Kushnir, V. Mitrochenco
NSC/KIPT, Kharkov, Ukraine
Y.L. Chi, X.W. Dai, C.D. Deng, M. Hou, X.C. Kong, R.L. Liu, W.B. Liu, C. Ma, G. Pei, S. Pei, H. Song, S. Wang, J.B. Zhao, Z.S. Zhou
IHEP, Beijing, People's Republic of China
Y. Gohar
ANL, Argonne, USA

In NSC KIPT, Kharkov, Ukraine a neutron source based on a subcritical assembly driven by a 100MeV/100kW electron linear accelerator will be constructed. This neutron source is an USA (ANL)-Ukraine (KIPT) Joint project, and its Accelerator will be designed and constructed by Institute of High Energy Physics (IHEP), China. The design and construction of such a Accelerator with high average beam current and low beam power losses is a technical challenging task. In the paper, the main accelerator features and current status are under discussion.

Slides THOAB203 [8.585 MB]

THOBB203

Study on Fabrication of Superconducting RF 9-cell Cavity for ILC at KEK

cavity, HOM, gun, status

3132

T. Saeki, Y. Ajima, K. Enami, H. Hayano, H. Inoue, E. Kako, S. Kato, S. Koike, T. Kubo, S. Noguchi, M. Satoh, M. Sawabe, T. Shishido, A. Terashima, N. Toge, K. Ueno, K. Umemori, K. Watanabe, Y. Watanabe, S. Yamaguchi, A. Yamamoto, Y. Yamamoto, M. Yamanaka, K. Yokoya
KEK, Ibaraki, Japan
Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
N. Kawabata, H. Nakamura, K. Nohara, M. Shinohara
SPS, Funabashi-shi, Japan
F. Yasuda
The University of Tokyo, Institute of Physics, Tokyo, Japan

We constructed a new facility for the fabrication of superconducting RF cavity at KEK from 2009 to 2011. In the facility, we have installed a deep-drawing machine, a half-cell trimming machine, an electron-beam welding machine, and a chemical etching room in one place. We started the study on the fabrication of 9-cell cavity for International Linear Collier (ILC) from 2009 using this facility. The study is focusing on the cost reduction with keeping high performance of cavity, and the goal is the establishment of mass-production procedure for ILC. This article reports the current status of the studies in CFF.

Slides THOBB203 [3.983 MB]

THPPA01

Realization of New Charge-state Stripper for High-power Uranium Ion Beams

stripper, ion, target, acceleration

3135

H. Imao
RIKEN Nishina Center, Wako, Japan

Recent works to realize the new charge-state stripper using recirculating helium gas are presented. Very limited lifetimes of conventional solid-state strippers due to huge dE/dx for very heavy ion beams (e.g., for uranium ions, several thousand times larger than protons at the energy around 10 MeV/u) were a principal bottleneck for their multi-stage acceleration at high intensities. The new stripping system is characterized by its infinite lifetime, efficient stripping and small beam degradation even for the world’s most intense uranium ion beams provided by the RIBF (more than 1 pμA at the injected energy of 11 MeV/u). Successful operations of the system in 2012 greatly contribute to the remarkable expansion of the accelerator performance of the RIBF that will allow an enormous breakthrough for exploring new domains of the nuclear world in the next several years; the peak intensity of the uranium beam has reached 15.1 pnA (almost 10¹¹ pps) at 345 MeV/u and the average intensity provided for the users has become ten times higher than it was in 2011.

Slides THPPA01 [6.535 MB]

THPPA02

Features and Applications of the Program ELEGANT

simulation, linac, FEL, lattice

3139

M. Borland
ANL, Argonne, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
ELEGANT is an open-source accelerator design and simulation code that has been in use and development for nearly two decades. In that time, it has evolved into a fairly general code for the design and modeling of linacs and storage rings, due in no small measure to suggestions and feedback from users world-wide. The code is best known for modeling of linacs for free electron lasers and particularly its relatively fast and straightforward modeling of coherent synchrotron radiation in magnetic bunch compression systems. This capability led to the discovery of a microbunching instability in such systems, thus helping to seed a new field of research. ELEGANT's capabilities are enhanced by the use of self-describing data files and the Self-Describing Data Sets (SDDS) toolkit. In this paper, we briefly review the features and capabilities of the code, then give a series of application examples from simulation of linear accelerators and storage rings.

Slides THPPA02 [0.477 MB]

THPEA002

The Accelerator Control System at ELSA

controls, diagnostics, synchrotron, emittance

3149

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

To fulfill the new requirements of the post-accelerator mode of the electron stretcher facility ELSA, a new computer control system was developed during the early 1990s. Providing capabilities to control and monitor the facility, it represents the top layer of a distributed control system composed of HP workstations, VME and field bus processors as well as linux based personal computer s. In addition to regular updates and improvements, the HP-UX operated part of the control system recently was ported to linux, so the outdated HP workstations could be replaced by a single linux PC. All reference values, for example the betatron tune or the extraction energy, can be specified using a window-based graphical user front end. They are directly computed to hardware compatible representations. Vice versa, measured beam parameters, e.g. the transversal beam emittance, are displayed for easy user access, allowing real time diagnostics. This abstraction layer allows for an intuitive approach to machine operation, requiring no detailed knowledge of the hardware implementation. In this contribution, the design principles and implementation at different layers of the control system are presented.

THPEA008

Study on the Energy Response of a Multi-layer Planar High Pressure Ionization Chamber using MCNP Program

photon, radiation, simulation, ion

3164

Y.D. Ding, P.F. Wang, Q.B. Wang, Q.J. Zhang
IHEP, Beijing, People's Republic of China

High pressure ionization chamber is widely used to detect various radiation fields due to its good energy response. A new Multi-layer planar high pressure ionization chamber is designed suitable for measuring directional radiation field of high dose rate, because of its high electric field strength. In this paper, MCNP program is used to simulate and calculate the energy response of this ionization chamber to obtain the energy response of high energy photons, which could not be obtained by experimental methods. The results show that this ionization chamber can measure photon radiation energy up to 10MeV.

THPEA015

Induced Radioactivity Research for Scraper

radioactivity, linac, radiation, synchrotron

3173

L.J. He, Y.K. Chen, W. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China

The 200MeV electron linac of NSRL is one of the earliest high-energy electron linear accelerators in China. The electrons are accelerated to 200MeV by five accelerating tubes and collimated by the scraper followed each accelerating tube. The scraper aperture is smaller than the accelerating tube,so some electrons will hit on the structure materials when they pass through them. These lost electrons will cause induced radioactivity due to bremsstrahlung, cascade shower and photo-nuclear reaction. This paper gives the simulation to different energy electrons lost at the corresponding scraper by EGSnrc. The results showed that electrons were lost mainly at the scraper during the accelerating period,and the actual measurement confirmed this. Meanwhile,the induced radionuclide types have been studied. Recently,the linac mentioned above has been retired because of upgrading. The equipments and materials removed are used to study induced radioactivity generated in different materials. The research will provide the theoretical basis for the similar accelerator decommissioning plan,and is also significant for accelerator structure design,material selection and radiation protection programs design.

THPEA026

Radiation Safety Interlock System for DCLS

radiation, controls, monitoring, dipole

3198

G. Wang, S. Liu, J.J. Lu, X. Xia, J.Q. Xu, Y. Xu, F. Yang
SINAP, Shanghai, People's Republic of China

Dalian Coherent Light Source (DCLS) is in the design phase currently and will be constructed in Dalian from 2013. It is a seeded HGHG-FEL, mainly consisting of one 300 MeV electron linear accelerator and one undulator. Radiation safety is one of the most important tasks for Dalian FEL. Radiation safety interlock system (RSIS) is designed to prevent personnel exposure to high radiation levels, based on the As Low As Reasonably Achievable (ALARA) principle. RSIS controls access to the radiation protection areas and monitors safety devices. Only if all the radiation safety conditions are satisfied, then the facility will be permitted to operate. Once any condition is broken, RSIS will send a signal to stop the electron beam immediately to guarantee radiation safety. The core component of RSIS utilizes Programmable Logic Controller (PLC), which is a proven and reliable technology in the field of industrial automatic control. All safety-relevant functions of RSIS are implemented with fail-safe components. The hard wiring cable of the peripheral signals for the safety-relevant functions is redundant. The safety interlock signals are sent via a fail-proof protocol and transferred redundantly.

THPEA031

REGAE LLRF Control System Overview

controls, LLRF, laser, feedback

3210

I. Rutkowski, L. Butkowski
Warsaw University of Technology, Institute of Electronic Systems, Warsaw, Poland
M. Hoffmann, H. Schlarb, Ch. Schmidt
DESY, Hamburg, Germany

The linear accelerator REGAE (Relativistic Electron Gun for Atomic Exploration) at DESY delivers electron bunches with a few femtosecond duration for time-resolved investigation of material structures in pump-probe configuration. To achieve sub-10fs resolution, the Low Level RF controls for the normal conducting S-band cavities must provide field stability of .005% in amplitude and of .005deg in phase. To achieve these demands, the recently developed LLRF control modules based on the Micro-Telecommunications Computing Architecture (MTCA.4) platform are used. For precise field detection and control a rear transition module (DRTM-DWC8VM1) housing 8 down-converters and 1 vector-modulator has been developed. The down-converted signals are transmitted to low-noise ADCs on an advanced mezzanine card (SIS8300L) with two high speed DACs driving the vector-modulator. The on board FPGA device runs the advanced control algorithms with minimum latency. Shot-to-shot learning feed forward and ultra-fast analog and digital feedbacks are applied. In this paper, the first results of the new RTM-AMC module pairs are presented together with the achievements and limitations on the RF field stability.

THPEA062

Magnetic Field Measurements for the IAC-RadiaBeam THz Project

dipole, quadrupole, radiation, FEL

3282

P. Buaphad, Y. Kim, M. Williams
ISU, Pocatello, Idaho, USA
A. Andrews, T. Downer, C.F. Eckman, Y. Kim, M. Smith
IAC, Pocatello, IDAHO, USA

At the Idaho Accelerator Center (IAC) of Idaho State University, recently, a new chicane with four dipoles and quadrupole triplet magnets were installed in a 44 MeV linac to perform the IAC-RadiaBeam Terahertz (THz) project. To generate high power THz radiation, a THz radiator with numerous periodic gratings was also installed downstream of the quadrupole triplet. However, the electron beam shape at the radiator has to be horizontally focused strip-like one due to a tiny radiator gap with a width of 1.2 mm, and electron bunch length should be about a few picosecond (ps) to generate high power THz radiation in the radiator. By using the quadrupole triplet and chicane dipoles, we can control the transverse beam profile and bunch length freely. In this paper, we report the measured field maps of the dipole and quadrupole magnets, their effective lengths, and field strength or gradient as a function of the magnet power supply current.

THPFI006

A New External Beamline for Detector Tests

quadrupole, simulation, dipole, extraction

3300

N. Heurich, F. Frommberger, P. Hänisch, W. Hillert, S. Patzelt
ELSA, Bonn, Germany

At the electron accelerator ELSA, a new external beamline is under construction, whose task is to provide a primary electron beam for detector tests. In the future, the accelerator facility will not only be offering an electron beam to the currently installed double polarization experiments for baryon spectroscopy, but to the new "Research and Technology Center Detector Physics" as well. This institution will be established near the accelerator in Bonn and is charged with the development of detectors for particle and astroparticle physics. The requirement for the new beamline is to be able to vary the beam parameters such as beam current and width over a wide range. With the resonance extraction method, it is possible to extract electrons with a maximum energy of 3.2 GeV slowly to the test area. A quasi-continuous external beam current of 1 fA to 100 pA can be offered. A further reduction of the beam current can be realized by utilizing the single-pulse operation mode at ELSA. The beam width can be changed in both transverse directions from 1 mm to 8 mm.

THPFI007

Increasing the Stability of the Electron Beam of the S-DALINAC

linac, feedback, acceleration, dipole

3303

F. Hug, T. Bahlo, C. Burandt, J. Conrad, L.E. Jürgensen, M. Kleinmann, M. Konrad, T. Kürzeder, N. Pietralla
TU Darmstadt, Darmstadt, Germany
R. Eichhorn
CLASSE, Ithaca, New York, USA

Funding: Funded by DFG through SFB 634
The S-DALINAC is a superconducting recirculating electron accelerator with a final energy of 130 MeV. It operates in cw at 3 GHz. It accelerates beams of either unpolarized or polarized electrons and is used as a source for nuclear- and astrophysical experiments at the university of Darmstadt since 1987. We will report on two future upgrade plans for increasing the operation stability of the accelerator: A high energy scraper system for collimating the beam before it is delivered to the experiments and a rf feedback system to fix the rf phase of the beam leaving the injector linac by measurements on a rf monitor.

THPFI010

High Energy RF Deflectors for the FERMI@Elettra project

linac, FEL, vacuum, wakefield

3309

M. Dal Forno, S. Biedron, D. Castronovo, P. Craievich, S. Di Mitri, D. La Civita, G. Penco, M. Petronio, F. Pradal, L. Rumiz, L. Sturari, D. Wang, D. Zangrando
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
P. Craievich
PSI, Villigen PSI, Switzerland
M. Dal Forno, M. Petronio, R. Vescovo
University of Trieste, Trieste, Italy
N. Faure
PMB-ALCEN, PEYNIER, France

Measuring and controlling the longitudinal phase space and the time-slice emittance of the electron bunch at 1.2 GeV entering in the undulator beam-lines, is crucial to obtain high FEL performances. In the FERMI@Elettra machine, two RF deflecting cavities have been installed at the end of the linac, in order to stretch the electron bunch horizontally and vertically, respectively. The two cavities are individually powered by the same klystron and a switch system is used to choose the deflection plane. This paper reports the RF measurements carried out during the acceptance test, the RF conditioning including the breakdown rate measurements. Finally, the commissioning with electron beam of the deflecting structure and a comparison of the measured electron bunch length evaluated by using the two deflectors are also reported.

THPFI012

Design of the cERL Vacuum System

vacuum, linac, diagnostics, gun

3315

Y. Tanimoto, S. Asaoka, T. Honda, T. Nogami, T. Obina, R. Takai
KEK, Ibaraki, Japan

The compact Energy Recovery Linac (cERL) is being constructed as a test accelerator for the ERL-based future light source at KEK. In the design of the cERL, electron beams with low normalized emittance (0.1 mm·mrad) and high average current (10 mA) are generated at a 500-kV gun, and accelerated up to 125 MeV at superconducting (SC) cavities that make energy recovery. The vacuum system should accommodate such high intensity, ultrashort bunch (0.1 ~ 3 ps) electron beams, and be designed so as to minimize its loss factor. Therefore, low impedance vacuum components, such as zero-gap flanges and rf-shielded screen monitors, have been developed. Extra high and clean vacuum is required in the vicinity of the SC cavities to maintain their high gradient operation, and those beam tubes are coated by Non-Evaporable Getter (NEG) films. Because of the low beam energy, photon absorbers are not necessary and the beam tubes can be made of stainless steel. However, the photon scrubbing effect is so limited that the beam tubes should be ready for in-situ bakeout and are wrapped with thin Kapton heaters, which are also useful for the NEG-coating activation.

THPFI040

DEVELOPMENT OF A TARGET SYSTEM FOR RARE ISOTOPE BEAM PRODUCTION WITH HIGH-POWER HEAVY-ION BEAMS*

target, radiation, ion, vacuum

3373

J.-W. Kim, S. Hong, J.H. Kim, M. Kim, J. Song
IBS, Daejeon, Republic of Korea

To produce rare isotope beams, in-flight fragmentation method utilizing a thin target and heavy-ion primary beam can be used. The existing facilities provide the maximum primary beam power of a few kW, while the next generation facility is planned to use hundreds of kW of 238U beam. We are designing a rare-isotope beam facility, which can provide U beam with the maximal power of 400 kW at the energy of 200 MeV/u. The high-power target studied is made of multi-slice rotating graphite to enhance radiation cooling. The total target thickness is roughly 2 mm with more than 10 slices. The resultant power density inside the target reaches above 50 MV/cm³. Numerical simulation for thermo-mechanical analysis has been performed using PHITS and ANSYS for single and multi-slice targets. Also, empirical test was made using 70-keV electron beam for a single-slice rotation target with the thickness of 0.2 mm. The results of simulation and e-beam tests will be presented.
* Work supported by Rare Isotope Science Program (RISP) through the National Research Foundation of Korea (NRF) funded by Ministry of Science, ICT and Future Planning (MSIP) (2011-0032011)

THPFI049

Evaluation of the NEG Coating Saturation Level after 3 Years of LHC Beam Operation

vacuum, proton, ion, luminosity

3397

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

The room temperature vacuum system of the Large Hadron Collider (LHC) at CERN system has been designed to ensure vacuum stability and beam lifetime of 100 h with nominal current of 0.56 A per beam at 7 TeV of energy. During last two years the LHC operated with proton beams at a maximum energy of 4 TeV, coasting for several hours each time, inducing high pressure due to different effects: synchrotron radiation, electron cloud and localized temperature increase. All these phenomena generated an important gas load from the vacuum chamber walls, which led in some cases to a partial or a total saturation of the NEG coating. To keep the design vacuum performances and to schedule technical interventions for NEG vacuum reactivation, it is necessary to take into account all these aspects and to regularly evaluate the saturation level of the NEG coating. This study analyses the saturation level of the NEG coated beam pipes in the LHC accelerator. Pressure reading variation without proton beams circulating are analysed and combined with laboratory studies of the NEG saturation behaviour and with Vacuum Stability Code (VASCO) simulations.

THPFI051

Radio-Frequency Multipacting as Quality Control of Coatings for e-Cloud Suppression

dipole, coupling, resonance, vacuum

3403

P. Costa Pinto, J. Bauche, S. Calatroni, F. Caspers, P. Edwards, M. Holz, M. Taborelli
CERN, Geneva, Switzerland

To mitigate electron clouds in particle accelerators, a carbon coating with low SEY has been developed. In the case of the SPS (Super Proton Synchrotron), which belongs to the LHC injector chain, testing the performance of coated beam pipes directly in the accelerator must cope with the schedule of the regular machine operation. For this reason an alternative instrument based on RF induced multipacting in a coaxial configuration has been designed for ex-situ characterization of the main bending dipoles of the SPS. In this contribution we report the results obtained before and after coating for two 6.4 meter dipoles with different cross sections of the vacuum chambers. The multipacting is monitored by measuring the pressure rise and the RF reflected power. After coating, the power threshold to induce multipacting is strongly reduced indicating a lower propensity for electron cloud. The impact of the RF coupling on the sensitivity of the technique is discussed.

THPFI052

Application of Atmospheric Plasma-sprayed Ferrite Layers for Particle Accelerators

plasma, vacuum, gun, resonance

3406

F. Caspers, M. Betz, S. Federmann, M. Taborelli
CERN, Geneva, Switzerland
K. K., C.A.M. Schulz
Surface Engineering Institute, RWTH Aachen University, Aachen, Germany
J.X. Wu
IMP, Lanzhou, People's Republic of China

A common problem in all kind of cavity like structures in particle accelerators is the occurrence of RF-resonances. Typically, ferrite plates attached to the walls of such structures like diagnostic devices, kickers or collimators, are used to dampen those undesired modes. However the heat transfer rate from these plates to the walls is rather limited. Brazing ferrite plates to the walls is not possible in most cases due to the different thermal expansion coefficients. To overcome those limitations, atmospheric plasma spraying techniques have been investigated. Ferrite layers with a thickness from 50 micron to about 300 micron can be deposited on metallic surfaces like stainless steel exhibiting good thermal contact and still reasonable absorption properties. In this paper the technological aspects of plasma deposition are discussed and results of specifically developed RF loss measurement procedures for such thin magnetically lossy layers on metal are presented. This kind of layers can also be applied for the production of high temperature RF power loads and related examples will be shown.

THPFI067

The Mechanical Design, Fabrication, and Performance of the DCCT for TPS

vacuum, shielding, storage-ring, high-voltage

3451

C.-C. Chang, C.K. Chan, J.-R. Chen, G.-Y. Hsiung, H.P. Hsueh
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

This paper describes the DC current transformers (DCCT), designed and fabricated for Taiwan Photon Source (TPS); including the mechanical structure, dissimilar material welding process for the DCCT chamber, electronically and vacuum performance testing. In the structure, a ceramic break disc is provided and jointed between to ends of the beam duct. The electrical connection path is interrupted in the beam duct adjacent to the transformer. To avoid the sensor measured the wall current and other unnecessary circulating currents. The DCCT toroid is independent installed outside of a vacuum beam duct to measure the average beam current. In order to reduce the influence of external magnetic field for the sensor, two layers of Mu metal shell are installed. The performance and progress for the DCCT are described in this paper.

THPFI079

Start-up of the NESTOR Facility Vacuum System

vacuum, storage-ring, ion, synchrotron

3478

A.Y. Zelinsky, A.N. Gordienko, V.A. Grevtsev, I.I. Karnaukhov, I.M. Karnaukhov, N.I. Mocheshnikov, A. Mytsykov, V.L. Skirda
NSC/KIPT, Kharkov, Ukraine

The Kharkov X-ray generator NESTOR based on Compton backscattering is under commissioning. The vacuum system of the complex integrates a linear accelerator-injector, the beam transport channel and the electron storage ring with energy range from 40 to 225 MeV. Elements of vacuum chambers, pumping facilities, cleaning surfaces procedures are described. Chambers are made of stainless steel (SS). After vacuum pretesting pressure 5 × 10^-9 Torr in the storage chambers ring achieved.

THPFI080

NSC KIPT Neutron Source on the Base of Subcritical Assembly Driven with Electron Linear Accelerator

neutron, target, klystron, radiation

3481

A.Y. Zelinsky, O. Bezditko, P.O. Demchenko, I.M. Karnaukhov, V. Oleinik, F.A. Peev, I. Ushakov, O.M. Vodin
NSC/KIPT, Kharkov, Ukraine
Y. Gohar
ANL, Argonne, USA

National Science Center “Kharkov Institute of Physics and Technology” (NSC KIPT, Kharkov, Ukraine) together with Argonne National Laboratory (ANL, USA) develops the conceptual project of a neutron source based on the sub-critical assembly driven by electron linear accelerator. The main functions of the subcritical assembly are support of the nuclear industry and medical researches. Reactor physics and material researchs will be carried out at the facility. For subcritical assembly design proven techniques and practices are used to enhance its utilization. The goal of the development is to create in Ukraine the experimental basis for neutron research based on safe intensive sources of neutrons. The main facility components are an electron linear accelerator, a system for electron beam transportation from linear accelerator to the target, neutron production target, subcritical assembly, biological shield, neutron channels and auxiliary supporting systems.

THPFI085

Status of PXIE MEBT Absorber Development

vacuum, radiation, simulation, gun

3490

A.V. Shemyakin, C.M. Baffes, K. Carlson, A.Z. Chen, Y.I. Eidelman, B.M. Hanna, L.R. Prost, J.T. Walton
Fermilab, Batavia, USA

Funding: Fermilab is operated by Fermi Research Alliance, LLC, under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
One of the goals of the Project X Injector Experiment (PXIE) at Fermilab is to demonstrate the capability to form an arbitrary bunch pattern from an initially CW 162.5 MHz H⁻ bunch train coming out of an RFQ. The bunch-by-bunch selection will be taking place in the 2.1 MeV Medium Energy Beam Transport (MEBT) by directing the undesired bunches onto an absorber that needs to withstand a beam power of up to 21 kW, focused onto a spot with a ~2 mm rms radius. A ¼ - size prototype of the absorber is manufactured, and its thermal properties are tested with an electron beam generating a peak power density similar to the one expected during normal operation of the PXIE beam line. The paper describes the absorber concept, the prototype, the testing procedure with the electron beam, and the latest results.

THPFI087

Measurements of Secondary Electron Yield of Metal Surfaces and Films with Exposure to a Realistic Accelerator Environment

vacuum, photon, gun, background

3493

W. Hartung, J.V. Conway, C.A. Dennett, S. Greenwald, J.-S. Kim, Y. Li, T.P. Moore, V. Omanovic
CLASSE, Ithaca, New York, USA

One of the central goals of the CESR Test Accelerator program is to understand electron cloud (EC) effects in lepton rings and how to mitigate them. To this end, measurements of the secondary electron yield (SEY) of technical surfaces are being done in CESR. The CESR in-situ system, in operation since 2010, allows for measurements of SEY as a function of incident electron energy and angle on samples that are exposed to a realistic accelerator environment, typically 5.3 GeV electrons and positrons. The system was designed for periodic measurements to observe beam conditioning of the SEY and discrimination between exposure to direct photons from synchrotron radiation versus scattered photons and cloud electrons. Measurements so far have been done on bare metal surfaces (aluminum, copper, stainless steel) and EC-mitigatory coatings (titanium nitride, amorphous carbon, diamond-like carbon). A significant decrease in SEY with exposure to beam was observed for all cases other than the amorphous C samples; for the latter, the SEY remained near 1, independent of beam exposure. The SEY results are being used to improve predictive models for EC build-up and EC-induced beam effects.

THPFI088

Electron Cloud Diagnostic Chambers with Various EC-suppression Coatings

vacuum, positron, ion, pick-up

3496

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

Funding: Work supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the U.S. Department of Energy DE-FC02-08ER41538
Suppression of electron cloud (EC) growth and density is critical for many high intensity accelerators of positively charged particles, such as positron rings for Super KEKB and ILC’s positron damping ring. Among various suppression techniques, passive coating with low secondary electron emission (SEY) coefficient is the most economic method. During CesrTA EC study program, we have created two dedicated short sections in the CESR vacuum system to study effectiveness of various SEY reduction coatings. During last 4 years, six one-meter-long EC study vacuum chambers were constructed, and rotated through these short sections. The EC chambers were not only equipped with EC diagnostics (including a RFA and RF-shield pickups), they were also installed in CESR with vacuum instrument, including a cold cathode ion gauge and a residual gas analyzer. With these EC study chambers, EC-suppression effectiveness of TiN, amorphous carbon and diamond-like carbon coatings were evaluated, relative to bare aluminum chamber. In this report, we will report vacuum properties of these coatings. In particular, the photon-induced desorption and beam conditioning histories are presented.

THPFI091

Simultaneous Four-hall Operation for 12 GeV CEBAF

linac, extraction, recirculation, laser

3502

R. Kazimi
JLAB, Newport News, Virginia, USA

Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The CEBAF accelerator at Jefferson lab will have a new experimental hall, Hall D, added to its existing three halls as a part of the ongoing 12 GeV upgrade. Under the present CEBAF design, there is no option for sending beam to all four halls simultaneously. At least one hall has to stay down during the machine operation. A new pattern for interleaving the beam bunches is introduced that allows simultaneous operation of all four halls and provide opportunity for additional future experimental beams. The new configuration presents only a minimal change to the existing CEBAF extraction system. In fact all the lower pass extractions will stay as they are and only the frequency of 5th-pass horizontal RF separator will change. In order to make room for the new Hall D beam among the existing three beams, the beam repetition rate is reduced only for the halls taking beam at the highest pass. This and other details of the new configuration and beam pattern will be presented and discussed. A separate paper in this conference will cover the implementation choices including changes to the beam source and extraction region.*
* "Source and Extraction for simultaneous Four-Hall beam delivery system at CEBAF", proceedings of this conference.

THPFI093

Device and Technique for In-situ Coating of the RHIC Cold Bore Vacuum Tubes with Thick OFHC

vacuum, cathode, cryogenics, superconducting-magnet

3508

A. Hershcovitch, M. Blaskiewicz, J.M. Brennan, W. Fischer, C.J. Liaw, W. Meng, R.J. Todd
BNL, Upton, Long Island, New York, USA
A.X. Custer, M.Y. Erickson, N.Z. Jamshidi, H.J. Poole
PVI, Oxnard, USA
J.M. Jimenez, H. Neupert, M. Taborelli, C. Yin Vallgren
CERN, Geneva, Switzerland
N. Sochugov
Institute of High Current Electronics, Tomsk, Russia

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
To mitigate electron clouds & unacceptable ohmic heating problems in RHIC, we developed a robotic plasma deposition technique & device to in-situ coat the RHIC 316LN SS cold bore tubes based on mobile mole mounted magnetrons for OFHC deposition. Scrubbed Cu has low SEY and suppress electron cloud formation. Room temperature RF resistivity measurement of Cu coated SS RHIC tube samples indicate that 10 μm of Cu coating has conductivity close to copper tubing. A 50 cm long copper cathode magnetron, mounted on a carriage with spring loaded wheels, was successfully operated, traversed magnet interconnect bellows and adjusted for variations in vacuum tube diameter, while keeping the magnetron centered. To maximize cathode lifetime, Cu cathode thickness was maximized its gap to vacuum tube minimized; movable magnet package is used. Novel cabling and vacuum-atmosphere interface system is being developed. Deposition experiments show no indentation in or damage to coating after wheels roll over coated areas; i.e. train like assembly option is a viable for in-situ RHIC coating. Details of experimental setup & coating of full-scale magnet tube sandwiched between bellows will be presented.

THPME002

Compact High-Tc 2G Superconducting Solenoid for Superconducting RF Electron Gun

solenoid, cavity, gun, SRF

3514

G. Nielsen, A. Baurichter, N. Hauge, E.K. Krauthammer
Danfysik A/S, Taastrup, Denmark

A solenoid with second generation (2G) high-temperature superconducting (HTS) coils for use in the superconducting RF electron gun of the WiFEL free electron laser at the University of Wisconsin, Madison, has successfully been designed, manufactured, tested and magnetically characterized at Danfysik. The solenoid is designed to operate in the temperature range between 5 K and 70 K. A stack of 16 serially connected pancake coils wound from SuperPower 2G HTS-tape is mounted inside a cylindrical iron yoke with end caps. The solenoid was designed with an excitation current margin of at least 130 % of the nominal operation current in the whole temperature range. At operation, 17.2 kA-turns yield a center field of 0.20 T and a field integral of 3.1 T² mm, with very small integrated field errors. With a yoke outer diameter of 176 mm and a total length of 136 mm, the solenoid is very compact, and can therefore be placed very close to the RF cavity, improving its emittance compensating efficiency. Careful magnetic design minimizes the leak field at the SC cavity surface. Heat dissipation is negligible hence conduction cooling through copper braids attached to the iron yoke is sufficient.

THPME013

MAGNET SUBSYSTEM OF HLS II

dipole, storage-ring, quadrupole, beam-transport

3537

Q. Luo, N. Chen, G. Feng, N. Hu
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Work supported by Natural Science Foundation of China 11005106
To improve the performance of the Hefei Light Source (HLS), in particular to get higher brilliance synchrotron radiation and increase the number of straight section insertion devices, NSRL is now upgrading HLS to HLS II. Most of the magnets had to be replaced in this project. To measure the magnets, set of the magnetic measurement equipment in NSRL are also re-built. New magnets are sample measured, the discreteness and uniformity of integrated magnetic field all meet the requirements. Piecewise fitting and electron tracking of bending magnets for injector and beam transport line were performed and the results showed that the electron trajectory fitted the physical design well.

THPME027

Design and Fabrication of Prototype Phase Shifter for PAL XFEL

undulator, FEL, controls, radiation

3564

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

Pohang Accelerator Laboratory(PAL) is developing a SASE X-ray Free Electron Laser based on 10 GeV linear accelerator. Prototype phase shifters are being developed to be used for the X-ray and Soft X-ray undulator line. The phase shifters will be used to adjust the phase of the electron beam with respect to that of the radiation field. Two prototype phase shifters are being developed. One is based on the EU-XFEL phase shifter using zero-potential iron yoke, and the other one is similar to FERMI phase shifter where only permanent magnets are used. Driving system consists of 5 phase stepping motor, left/right handed ball screw and absolute linear encoder. In this paper, we describe the design, fabrication and test results of the two phase shifter prototypes.

THPME040

The Installation and Commissioning of the Helium Cryogenic System for theTPS Project

cryogenics, SRF, storage-ring, controls

3600

H.H. Tsai, S.-H. Chang, W.-S. Chiou, F. Z. Hsiao, C.K. Kuan, H.C. Li, T.F. Lin, C.P. Liu
NSRRC, Hsinchu, Taiwan

The construction of an electron accelerator with energy 3 GeV is under way for high brilliance and flux X-ray photon source at NSRRC. There will be eventually four superconducting radio frequency (SRF) cavities installed to maintain the electron energy. The helium cryogenic system has been designed and fabricated to provide the required liquid helium for SRF cavities. The cryogenic system consists of the 700-W refrigerator, the 315-kW variant frequency compressor, the oil removal system, the recovery compressor system, the gas helium buffer tanks, and one 7000-L liquid helium Dewar. The overall system installation and commissioning will be presented and discussed in this paper.

THPWA002

Optimization of the Photoneutron Flux Emitted by an Electron Accelerator for Neutron Interrogation Applications using MCNPX and TRIPOLI-4 Monte Carlo Codes

target, neutron, photon, simulation

3630

A. Sari, F. Carrel
CEA/DRT/LIST, Gif-sur-Yvette Cedex, France
C. Jouanne, A. Lyoussi, O. Petit
CEA, Gif-sur-Yvette, France

Various applications require neutron interrogation to detect special nuclear material. In a previous study*, we demonstrated the feasibility of this technique using the photoneutron flux emitted by a 16 MeV linear electron accelerator. This approach enables to reach average emission intensity on the order of one decade beyond the one produced by deuterium-tritium neutron generators traditionally used for such applications. Higher average emission intensities of the photoneutron flux would enable to expand boundaries of neutron interrogation. This new study aims at optimizing the photoneutron flux emitted by an electron accelerator. In order to ensure accuracy and reliability of our results, two Monte Carlo particle transport codes were used in parallel in this study: MCNPX developed by Los Alamos National Laboratory, and TRIPOLI-4 developed by the French Alternative Energies and Atomic Energy Commission. Potential discrepancies between results obtained with the two codes were investigated. Furthermore, careful attention was given to minimize the high-energy photon beam contained in the photoneutron flux in order to reduce spurious photofission reactions during measurements.
*A. Sari et al., IEEE Trans. Nucl. Sci., vol. 59, no.3, pp. 605-611, 2012.

THPWA010

Application of X-band 30 MeV Linac Neutron Source to Nuclear Material Analysis for Fukushima Nuclear Plant Accident

neutron, linac, target, scattering

3648

M. Uesaka, K. Dobashi, T. Fujiwara
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
H. Harada
JAEA, Ibaraki-ken, Japan
K. Tagi
University of Tokyo, Tokyo, Japan
M. Yamamoto
Accuthera Inc., Kawasaki, Kanagawa, Japan

We plan to use our X-band (11.424GHz) electron linac as a neutron source for the nuclear analysis for the Fukushima nuclear plant accident. Quantitative material analysis and forensics for nuclear security will start several years later after the safe settlement of the accident is established. For the purpose, we should now accumulate more precise nuclear data of U, Pu, TRU and MA especially in epithermal (0.1-10 eV) neutrons. Therefore, we have decided to move the linac into the core of the experimental nuclear reactor “Yayoi” which is now under the decommission procedure. First we plan to perform the TOF (Time Of Flight) transmission measurement of the total cross sections of the nuclei for 0.1-10 eV neutrons. Electron energy, macro-pulse length, power and neutron yield are ~30 MeV, 100 ns – 1 micros, <0.5 kW and <10¹² n/s, respectively. Optimization of the design of a neutron target (Ta, W, U), TOF line and neutron detector (Ce:LiCAF) of high sensitivity and fast response is underway. Installation, commissioning and measurement starts in 2014. Detailed design and way how to contribute to the analysis of the Fukushima nuclear plant accident will be presented.

THPWA011

Concepts of 220 MeV Racetrack Microtron for Non-destructive Nuclear Material Detection System

microtron, acceleration, gun, simulation

3651

T. Hori, T. Kii, R. Kinjo, H. Ohgaki, M. Omer, H. Zen
Kyoto University, Institute for Advanced Energy, Kyoto, Japan
I. Daito, R. Hajima, T. Hayakawa, M. Kando, H. Kotaki
JAEA, Kyoto, Japan
F. Sakai
SHI, Tokyo, Japan

Funding: Japan Science and Technology Agency Special Coordination Funds for Promoting Science and Technology (Grant No. 066)
A nuclear material detection system (NMDS) using the quasi-monochromatic gamma-ray beam from a laser Compton scattering (LCS) source is proposed for the container inspection, where nuclear resonance fluorescence method is to be employed for the specific isotope identification such as U-235. In the system an electron beam of good quality at about 220-MeV must be provided for LCS. One of the most promising electron source is a compact electron accelerator named racetrack microtron (RTM). Some concepts of RTM suitable for NMDS and expected beam qualities will be presented.

THPWA012

The Development of a New Type of Electron Microscope using Superconducting RF Acceleration

cavity, acceleration, gun, cathode

3654

N. Higashi
The University of Tokyo, Graduate School of Science, Tokyo, Japan
A. Enomoto, Y. Funahashi, T. Furuya, Y. Kamiya, S. Michizono, M. Nishiwaki, H. Sakai, M. Sawabe, K. Ueno, M. Yamamoto
KEK, Ibaraki, Japan
M. Kuriki
HU/AdSM, Higashi-Hiroshima, Japan
S. Yamashita
ICEPP, Tokyo, Japan

We are developing a new type of electron microscope (EM), which adopts RF acceleration in order to exceed the energy limit of DC acceleration used in conventional EMs. It enables us to make a high-voltage EM more compact and to examine thicker specimens, and possibly to get better spatial resolution. Using a superconducting RF cavity, we can operate the EM in CW mode to obtain a beam flux comparable to that in DC mode. Low energy dispersion ΔE/E , e.g. 10^-6 or better, is required for good spatial resolution in EMs, while it is usually between 10^-3 to 10^-4 in accelerators. We have thus designed a special type of cavity that can be excited with the fundamental and second-harmonic frequencies simultaneously; TM010 and TM020. With the two-mode cavity, the energy dispersion of the order of 10^-5 would be obtained by modifying the peak of accelerating field to be flattened. As the proof-of-principle of our concept, we are developing the prototype using a 300 keV transmission electron microscope (TEM), to which a new photocathode gun and the two-mode cavity are attached. We have already manufactured the cavity and it is under test, and the gun is under construction.

THPWA013

Direct Diagnostic Technique of High-intensity Laser Profile based on Laser-Compton Scattering

laser, solenoid, gun, cathode

3657

Y. Yoshida, A. Endo, K. Sakaue, R. Sato, M. Washio
Waseda University, Tokyo, Japan

Funding: Work supported by NEDO (New Energy and Industrial Technology Development Organization).
A high-intensity laser is essential for the LPP (Laser Produced Plasma) EUV generation, which is studied as the next generation light source of ultra-fine semiconductor lithography. Nevertheless, there is no way to directly measure the profile of high-intensity laser. Therefore, we have been developing a method for measuring high-intensity laser profile based on the laser-Compton scattering using a Cs-Te photo cathode RF-Gun at Waseda University. In this diagnostic technique, laser profile is obtained by scanning the extremely-focused electron beam, which is about 10μm by solenoid lens. We have obtained the 10μm beam size by solenoid lens using tracking code GPT (General Particle Tracer) by optimizing the beam parameter and lens shape. Recently, we have installed solenoid lens and generated focused beam. The focused beam size was evaluated by using radiochromic film called GAFCHROMIC dosimetry film type HD-810. In this conference, we will report the results of GPT simulations, beam size measurements and future prospects.

THPWA014

Development of Photon-induced Positron Annihilation Lifetime Spectroscopy using an S-band Compact Electron Linac

positron, photon, linac, laser

3660

Y. Taira, R. Kuroda, B.E. O'Rourke, N. Oshima, R. Suzuki, M. Tanaka, H. Toyokawa
AIST, Tsukuba, Ibaraki, Japan
K. Watanabe
Nagoya University, Nagoya, Japan
T. Yanagida
Kyushu Institute of Technology, Fukuoka, Japan

Funding: This work was supported by Grants-in-Aid for Scientific Research (22360297)
Positron annihilation lifetime spectroscopy (PALS) is a very sensitive tool to characterize materials and study defects at the nanometer scale. However, the application of PALS has been restricted to thin samples because of the limited range of positrons in materials. PALS for thick samples is possible by using high energy photons to create positrons inside the sample via pair production. This technique is called photon-induced positron annihilation lifetime spectroscopy (PiPALS). We have developed a novel PiPALS system using ultra-short photon pulses based on bremsstrahlung radiation to carry out in-situ measurement of structural materials under special conditions (piping for supercritical water and nuclear reactor materials). Intense, ultra-short photon pulses with energies up to 40 MeV can be generated by using an electron linear accelerator with photocathode rf gun system at AIST. In this conference, we will present the experimental result of the positron annihilation lifetime spectrum of a metal target by using ultra-short photon pulses*.
*Y. Taira et al., Rad. Phys. and Chem., accepted for publication 2012.

THPWA016

Design and Optimization of the Target in Electron Linear Accelerator

target, simulation, radiation, photon

3663

Q. Gao, H.B. Chen, J. Shi, H. Zha
TUB, Beijing, People's Republic of China

The target in electron linear accelerator plays an important role in the production of photon. Different materials and thickness of target have influence on dose rate. For 6MeV electron beam, this study gives the thickness of target for several materials in which the dose rate can be higher and drain electron can be lower. Then a X-ray target had been designed for 6MeV electron linac by FLUKA simulations. It can deliver 1000 cGy/min at 1 meter in front of the target if providing 6 MeV electron beam with 100uA current, which can achieve high-dose rate radiotherapy.

THPWA019

THEORY RESEARCH ON APPLICATION OF CT TECHNOLOGY TO SHIELDED NUCLEAR MATERIAL DISCRIMINATION

neutron, radiation, resonance, factory

3669

Y. Zhang, H.B. Chen, Q. Gao, J. Shi
TUB, Beijing, People's Republic of China

Smuggling of nuclear material is a serious threat to security of international society. Formal research on nuclear material discrimination can fulfil customs inspection requirement. This paper designs a situation that nuclear material which is packaged and shielded by heavy metal need to be discriminated accurately on the condition that the object being detected cannot be dismantled. Calculation results prove nuclear material could be discriminated accurately while the ideal condition is fulfilled. If multi-energy X-ray source is used the discrimination accuracy is declined. However the accuracy could be improved while energy spectrum shaping technique is used.

THPWA021

Studies of Density Distribution and Emittance Measurement for High Current Electronic Beam

emittance, gun, simulation, ion

3672

Q.C. Li, Z.-F. He, J.M. Huang, D.M. Li, Y.-T. Zhang, X.K. Zhu
SINAP, Shanghai, People's Republic of China

Beam density distribution and emittance are the important parameters of an accelerator. The accurate emittance measurement has an important reference significance for the design of accelerating tube, and provides a design basis for the aperture size of accelerating tube. This paper introduces a beam measurement method which uses multiwire, can rotate in the horizontal plane and adjust in the Z coordinate. The results of simulation show that this method can accurately measure the beam density distribution and emittance, and the accuracy can meet the requirements of applied accelerator.

THPWA022

An 800kV 30mA Line-Frequency Cockcroft-Walton Dc Generator Using Gas Insulated Transformer for Radiation Application

high-voltage, power-supply, impedance, radiation

3675

Y.H. Liu, H.L. Guo, Z.-F. He, D.M. Li, M.X. Li, W.G. Shi, H.J. Su, S.L. Wang, Y.J. Yang, J.L. Zhang, Y.-T. Zhang
SINAP, Shanghai, People's Republic of China

The design and construction of a line-frequency 800 kV Cockcroft-Walton DC generator using gas insulated transformers are described, as well as the motive to develop it into radiation application. Several features are underlined, preliminary test results of the prototype presented and some problems encountered discussed.

THPWA023

Research on Modeling of the High-density Current Electron Gun System Based on T-S Fuzzy Model

gun, controls, simulation, cathode

3678

B. Lv, D.M. Li, H.J. Su
SINAP, Shanghai, People's Republic of China

Abstract: The stability of the electron beam is considered as an important performance of industrial electron accelerators. For the beam control system of the accelerator, it is significant to obtain the accurate model of the electron gun system. The paper presents a fuzzy modeling method based on the Takagi-Sugeno (T-S) fuzzy model. A T-S model can be obtained using the system identification algorithms from input-output data. In our approach, fuzzy c-means (FCM) clustering algorithm is applied to identify the model structure. And a hybrid method based on quantum-inspired differential evolution algorithm (QDE) and genetic algorithm (GA) is proposed to learn the parameters of T-S fuzzy model. Experiments on the Box-Jenkins gas furnace data have verified the validity of the modeling approach. The simulation results show that the T-S fuzzy model is very well to describe the electron gun system and reveal its performance.

THPWA027

Evaluation of Zero-failure Data in Transient Ionizing Radiation Based on Ordering Method in the Sample Space

radiation, laser, target, simulation

3681

X.Y. Bai, X.M. Jin, R.B. Li, Y. Liu, Q. Ma, Ch. Qi
NINT, Xi'an, People's Republic of China

The conventional method for the evaluation of data in lot acceptance testing (LAT) of transient ionizing radiation is non-parametric method. But the evaluation results are very conservative. After the discovery of data in transient ionizing radiation belonging to one universal data model “case 1 interval censored data”, ordering method in the sample space was introduced and applied to evaluate zero-failure data and was compared with non-parametric method both theoretically and via a practical LAT on QG-Ⅰ. Through the comparisons, it is concluded that ordering method can expand the scope of dose rate corresponding to the same lower confidence limit. It improves data utilization and this improvement could have practical significance in LAT. It can reduce requirements for the radiation source and can also reduce the number of trials.

THPWA028

Analysis of Uncertainty of Dose Rate Measurement on the Accelerator “QiangGuang-I”

radiation, photon, factory, target

3684

R.B. Li, X.Y. Bai, X.M. Jin, Q. Ma, C. Qi, G.Z. Wang
NINT, Xi'an, People's Republic of China

“QiangGuang-I”, working on short pulse state, can be used to research the transient radiation effects on electronic devices. The measurement of dose rate is significant for assessing devices’ radiation-resistant ability. This paper comprehensively analyzes the originations of uncertainty on dose rate’s measurement, such as thermoluminescent dosemeter’s linearity degree and response to X-rays energy spectrum, testing instruments’ resolution, waveforms’ transmission distortion , and positional error; figures out the extended uncertainty. The result shows that the expanded uncertainty of dose rate’s measurement is less than 20%, which is satisfactory for researching on devices’ transient radiation effects, and proves that the method used to measure dose rate is reasonable.

THPWA029

Transient Ionizing Radiation Effect of Bipolar Operational Amplifiers to Pulsed X-rays

radiation, controls, feedback, injection

3687

X.M. Jin
Xiaoming Jin, People's Republic of China
X.Y. Bai, R.B. Li, D.S. Lin, Q. Ma, C. Qi, G.Z. Wang, S.C. Yang
NINT, Xi'an, People's Republic of China

Abstract – The pulsed ionizing radiation effect of monolithic operational amplifiers is investigated using a flash X-ray facility. The experimental results show that the pulsed ionizing radiation produces voltage surges in the devices and the output voltage recovers linearly after transient disturbance which includes a negative peak and a positive peak. The recovery time depends on the amplitude of the positive peak and the inherent slew rate of the devices. The degradation of transient disturbance amplitude and the recovery time versus ionizing dose rate of pulsed X-rays is researched. The relationship of circuit effects to physical mechanisms is investigated in detail. The photocurrent induced by transient ionizing radiation in the PN junctions in integrated circuits is responsible for the electrical degradation. Keywords – Transient ionizing Radiation effect, Transient disturbance, Photocurrent, integrated circuits

THPWA030

Design and Prototype Test of C-band Standing-wave Accelerating Structure to Enhance RF Phase Focusing

focusing, coupling, bunching, simulation

3690

H. Yang, M.-H. Cho, W. Namkung, S.-G. Shin
POSTECH, Pohang, Kyungbuk, Republic of Korea
S.H. Kim
ANL, Argonne, USA
J.-S. Oh
NFRI, Daejon, Republic of Korea

Funding: This research was financially supported by the MOTIV, KIAT and Dongnam Institute for Regional Program Evaluation through the Leading Industry Development for Economic Region
A C-band standing-wave accelerator for X-ray and electron beam sources of medical radiotherapy is designed and being fabricated. The accelerator system is to be operated in two modes, using the X-ray and electron beams. Because of the energy loss in electron mode, the accelerator is capable of producing 6-MeV, 100-mA electron beams with peak 2-MW RF power, and 7.5-MeV, 20 mA electron beams with peak 2.5-MW RF power. The beam radius at the end of column was < 0.5 mm without focusing magnets in PARMELA simulations, because the bunching cells are designed to enhance the RF phase focusing. Each cavity in the bunching and normal cells was designed by the MWS code to maximize the effective shunt impedance with 3.8% inter-cell coupling in normal cells. The dimensions of normal cells were determined by the low power RF test of prototype cells with 5711.06-MHz resonant frequency and 3.5% inter-cell coupling. In this paper, we present details of the accelerator design and prototype test.

THPWA033

Material Discrimination Technology for Cargo Inspection with Pulse-to-pulse Linear Electron Accelerator

radiation, controls, collimation, target

3699

S. Ogorodnikov, R. Apevalov, M. Arlychev, I. Polevchenko, A. Rodionov, I.E. Shevelev
Scantronic Systems, St. Petersburg, Russia

In the present article a complex of technological solutions based on 6/3.5 MeV pulse-to-pulse linear accelerator, detectors made of CWO scintillators coupled with PIN photodiodes and image processing algorithms proposed. Energies, dose rate and other parameters of accelerator were optimized to reach high performance of the x-ray system and to carry out robust and reliable material discrimination in the mass thickness range up to 120 g/cm² at least. Evaluation of effective atomic number of materials of main three groups (organics, mineral/light metals, metals) was fulfilled with preciseness ±1 for the optimal mass thickness range at the scanning speed 60 cm/s. Instrument for evaluation of physical mass of the separate objects on the image is proposed and realized.

THPWA034

Overview of CERN Technology Transfer Strategy and Accelerator-related Activities

vacuum, linac, target, proton

3702

E. Chesta, A. Bertarelli, F. Caspers, P. Chiggiato, S. Sgobba, T. Stora, M. Taborelli, W. Wuensch
CERN, Geneva, Switzerland

CERN, the European Organization for Nuclear Research, is actively engaged in identifying technologies developed for its accelerator complex that could be profitably used by partner research organizations or commercial companies in applications with potentially high socio-economic impact beyond pure fundamental physics research. In the first part of the paper, an overview of CERN current strategy in the field of Technology Transfer and Intellectual Property Management will be presented, with details on the most effective models, implementation tools and processes developed to achieve satisfactory dissemination and valorisation of the knowledge generated within the Organization. In the second part, CERN currently available technology portfolio will be described with focus on cases originated from the Accelerator and Technology Sector. A selection of promising on-going projects embracing a variety of technology fields and application areas will be detailed to showcase technical challenges and possible benefits of initiatives driven by (but not limited to) the needs of CERN scientific programme.

THPWA036

Implementation and Commissioning of the New Electron Beam Test Facility (EBTF) at Daresbury Laboratory for Industrial Accelerator System

gun, laser, diagnostics, cathode

3708

P.A. McIntosh, D. Angal-Kalinin, R.K. Buckley, S.R. Buckley, J.A. Clarke, B.D. Fell, A.R. Goulden, C. Hill, F. Jackson, S.P. Jamison, J.K. Jones, A. Kalinin, B.P.M. Liggins, J.W. McKenzie, K.J. Middleman, B.L. Militsyn, T.C.Q. Noakes, Y.M. Saveliev, B.J.A. Shepherd, S.L. Smith, T.T. Thakker, A.E. Wheelhouse
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
N. Bliss, G. Cox, G.P. Diakun, A. Gleeson, L. Ma, B.G. Martlew, A.J. Moss, K. Robertson, M.D. Roper, R.J. Smith
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

The EBTF facility will provide enabling infrastructures targeted at the development and testing of novel and compact accelerator technologies, specifically through partnership with industry and aimed at addressing applications in medicine, health, security, energy and industrial processing. The facility has now been implemented at Daresbury Laboratory and the commissioning of the critical accelerator systems has been performed. The facility is now preparing for first exploitation with partnering industries that will be able to utilise the electron beam parameters available on EBTF to either demonstrate new techniques and/or processes or otherwise develop new technologies for future commercial realisation.

THPWA044

R&D into Laser Applications for Accelerators

laser, cathode, acceleration, vacuum

3729

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

Funding: Work supported by the EU under Grant Agreement 289191.
Lasers can be used for the generation of high brightness electron and exotic ion beams, the acceleration of particles with the highest accelerating gradients, as well as for the characterization of many complex particle beams by means of laser-based beam diagnostics methods. In addition, (free electron) lasers can be used for achieving the highest time resolution and strongest fields for experiments in atomic physics, chemistry and biology, i.e. for studies into the dynamics of some of the most fundamental processes in nature. Without constant progress in laser technology and close collaboration between laser experts and accelerator scientists, many of today's most advanced experiments would simply be impossible. The LA3NET consortium combines developments into laser technology and sensors with their application at advanced accelerator facilities, providing complex beams ranging from highest brightness electron beams to high intensity proton beams. This contribution presents the consortium's broad, yet closely interconnected experimental program.

THPWA045

Accelerator R&D in the QUASAR Group

antiproton, storage-ring, ion, diagnostics

3732

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

Funding: Work supported by the STFC Cockcroft Institute Core Grant No. ST/G008248/1, HGF and GSI under contract VH-NG-328 and the EU under contracts 215080, 289181 and 289485.
The QUASAR Group is a pan-European research group based at the Cockcroft Institute in the UK. It carries out R&D into methods to decelerate and store very low energy antiproton and exotic ion beams, beam diagnostics developments for medical accelerators, including imaging and dosimetry, as well as opto-electronics and laser applications. This contribution presents the latest results of the Group's studies into the USR/ELENA/AEgIS antimatter facilities, novel least destructive beam profile monitors for medical and industry applications, as well as laser applications for accelerators, includingμaccelerators and a laser velocimeter.

THPWA046

Accelerator Optimization within the oPAC Project

linac, cryogenics, radiation, simulation

3735

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

Funding: Work supported by the EU under Grant Agreement 289485.
Many of the today’s most advanced research infrastructures rely on the use of particle accelerators. This includes for example synchrotron light sources and FELs, high intensity hadron accelerators for the generation of exotic beams and spallation sources, as well as much smaller accelerator facilities for precision experiments and fundamental studies. Moreover, accelerators are very important for many commercial applications, such as for example medical applications, material studies and treatment, lithography, or security applications, such as scanners at airports or cargo stations. The full potential of any accelerator can only be exploited if the performance of all its parts are continuously optimized, if numerical tools are made available that allow for developing and improving advanced machine designs, if methods are developed in partnership between the academic and industry sectors to monitor beams with ever higher intensities and brightness, shorter pulse lengths or smaller dimensions. This contribution presents the R&D program of the oPAC project that optimizes existing and future accelerators.

THPWA048

New Generation X-band Linacs for Medical and Industrial Appplications

linac, RF-structure, radiation, beam-losses

3741

A.V. Mishin, S. Proskin
RMX, North Andover, USA

The proposed designs of the new X-band linear accelerators for industrial and medical applications are based on a well-known side-coupled RF structure. The immediate applications envisioned for the new linear accelerators are security screening and intraoperative radiotherapy (IORT). The new design has promising features and presents cost reduction potential for electron beam and X-ray systems used in medical, industrial, and security screening applications.

THPWA051

Compact, Inexpensive X-band Linacs as Radioactive Isotope Source Replacements

linac, gun, simulation, radiation

3746

S. Boucher, R.B. Agustsson, L. Faillace, J.J. Hartzell, A.Y. Murokh, A.V. Smirnov, S. Storms, K.E. Woods
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 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 testing of these linacs at RadiaBeam. Future development plans will also be discussed.

THPWO021

Gabor Lens Performance Studies at the GSI High Current Test Injector

emittance, ion, beam-transport, space-charge

3806

K. Schulte, M. Droba, O. Meusel, U. Ratzinger
IAP, Frankfurt am Main, Germany
A. Adonin, R. Berezov, R. Hollinger, J. Pfister
GSI, Darmstadt, Germany

At the Institute for Applied Physics (IAP) the application of Gabor space charge lenses as a focusing device for low energy ion beams has already been studied for several years. Inside Gabor lenses electrons are confined by external fields. In case of a homogeneously distributed electron cloud the resulting linear electric space charge field enables the focusing of high intensity heavy ion beams without aberrations. Therefore, the Gabor lens is a promising approach for mass-independent focusing and possible space charge compensation of ion beams. In mid-2012 the performance of a prototype lens has successfully been tested at the GSI High Current Test Injector (HOSTI). GSI and IAP are currently investigating the possible application of such a device for the continuous operation at the High Current Injector (HSI) for FAIR. This contribution will present the results of beam transport experiments at HOSTI as well as the determination of related plasma properties.

THPWO035

Numerical Study on the Effect of Magnetic Shield of a Bunch Shape Monitor in J-PARC Linac

linac, simulation, beam-transport, quadrupole

3842

J. Tamura, H. Ao, A. Miura, N. Ouchi
JAEA/J-PARC, Tokai-mura, Japan
M. Ikegami
J-PARC, KEK & JAEA, Ibaraki-ken, Japan
T. Maruta
KEK/JAEA, Ibaraki-Ken, Japan
T. Miyao, K. Takata
KEK, Ibaraki, Japan

In the annual shutdown period of 2012, three bunch shape monitors (BSMs) have been installed to the J-PARC linac beam transport line at the downstream of the 181-MeV separated DTL. To measure the longitudinal micro-bunch shape, the BSM detects the electrons produced by the accelerated protons hitting the negatively energized wire. Due to the space limitation, the each BSM is installed at the center of the quadrupole doublet, where the fringe field from the quadrupole magnets exists. It has been observed that the fringe field significantly affects the orbit of the emitted electrons. To shield the magnetic field, iron plates have been inserted to the spaces between the quadrupole magnets and BSM. This causes changes of the total magnetic flux density (GL) and the amount of quadrupole component of the fringe field. In this paper, numerical estimation of the shield effect is presented.

THPWO038

Electron Stripping of High-intensity ²³⁸U Ion Beam with Recirculating He Gas

stripper, ion, target, acceleration

3851

H. Imao
RIKEN Nishina Center for Accelerator-Based Science, Wako, Saitama, Japan
T. Dantsuka, M. Fujimaki, N. Fukunishi, H. Hasebe, O. Kamigaito, M. Kase, H. Kuboki, K. Kumagai, T. Maie, H. Okuno, T. Watanabe, Y. Watanabe, K. Yamada, Y. Yano
RIKEN Nishina Center, Wako, Japan

Next-generation in-flight RI beam facilities such as RIBF and FRIB pursue powerful and energetic ²³⁸U ion beams to produce thousands of new isotopes. For their efficient acceleration, a durable electron stripper in the intermediate energy region around 10-20 MeV/u is indispensable. However, there is no available stripper for the U beams with the intensity of more than 1 puA so far because of the lifetime problem of thin solid strippers caused by high energy loss. 　In the present study, a novel electron stripping system employing high-flow rate He gas circulation (200 L/min) has been developed. He gas with the thickness of 0.6 mg/cm² is confined and separated from beamline vacuum using five-stage differentially-pumped sections. To avoid huge gas consumption, a clean gas recycling is achieved with multi-stage mechanical booster pump array. The recycling rate of He gas was achieved as more than 99%. The system was successfully operated in user runs with U³⁵⁺ beams more than 1 puA injected at 10.8 MeV/u for the first time. U⁶⁴⁺ beams were stably delivered to subsequent accelerators with the stripping efficiency of 23% without any deterioration of the system.

FRXAA01

Beam Dynamics and Collective Effects in "Ultimate" Storage Rings

emittance, ion, coupling, scattering

3981

M. Takao
JASRI/SPring-8, Hyogo-ken, Japan

This presentation will review the beam dynamics issues such as impedance driven instabilities, intrabeam scattering, and the Touschek lifetime in ultimate storage rings with very low emittance.

Slides FRXAA01 [11.245 MB]

FRYAA01

An Overview of Light Source Development in Asia

synchrotron, FEL, radiation, linac

4005

D. Wang
SINAP, Shanghai, People's Republic of China

This talk should cover the history of light sources that have been constructed, are now in operation or planned for the future in Asia. Advances in accelerator physics and technological innovations leading to steadily increasing machine performance and photon beam properties should be discussed.

Slides FRYAA01 [7.342 MB]