TUPWA —  Tuesday Posters (Washington)   (05-May-15   16:00—18:00)

Paper	Title	Page
TUPWA001	Measurement of the Incoherent Depth of Field Effect on Horizontal Beam Size Using a Synchrotron Light Interferometer	1391
	M.J. Boland SLSA, Clayton, Australia W.J. Corbett SLAC, Menlo Park, California, USA T.M. Mitsuhashi KEK, Ibaraki, Japan
	The electron beam size as measured using synchrotron light in a circular accelerator is influenced by the incoherent depth of field effect. This effect comes about due to the instantaneous opening angle of the emitted synchrotron radiation (SR) and the acceptance angle of the SR light monitor beamline. Measurements were made using a visible light interferometer at the visible light beamlines in three circular accelerators at ATF, SPEAR3 and AS. The first order spatial coherence of the beam was measured and from that the horizontal beam size was calculated. The data is compared with a theory of synchrotron radiation with and without the horizontal incoherent field depth effect.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA001
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TUPWA002	Layout Options for the AXXS Injector and XFEL	1394
	M.J. Boland, Y.E. Tan, D. Zhu SLSA, Clayton, Australia
	A new injector is being planned for the Australian Synchrotron that is designed to feed both an upgraded storage ring and an XFEL. The desire to fit the AXXS project on the same site as the existing light source presents several layout difficulties. Several options are studied and simulations are performed to check the impact each choice has on the beam performance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA002
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TUPWA004	Operator Roles at the Australian Synchrotron	1397
	D.C. McGilvery ASCo, Clayton, Victoria, Australia G. LeBlanc SLSA, Clayton, Australia
	The Accelerator Operators at the Australian Synchrotron undertake a wide variety of critical functions as part of their regular duties. In addition to normal Control Room duties, they play a major Role in Machine Physics, provide after hours support for Users on Beamlines and contribute extensively to the Controls and Database Development across the facility.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA004
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TUPWA005	Comparison of Bunch Compression Schemes for the AXXS FEL	1399
	T.K. Charles, D.M. Paganin Monash University, Faculty of Science, Clayton, Victoria, Australia A.A. Aksoy Ankara University, Accelerator Technologies Institute, Golbasi / Ankara, Turkey M.J. Boland, R.T. Dowd SLSA, Clayton, Australia A. Latina, D. Schulte CERN, Geneva, Switzerland
	Different types of electron bunch compression schemes are compared for the AXXS FEL design study. The main linac for the proposed machine is based on CLIC x-band structures. This choice leaves several options for the bunch compression schemes which impact the injection system RF band. Both harmonic linearization and phase modulation linearization are considered and their relative strengths and weaknesses compared. Simulations were performed to compare the performance of an s-band injector with a higher harmonic RF linearization and an x-band injector. One motivation for the study is to optimise the length of the AXXS machine, allowing the linac to fit onto the proposed and also act as the injector to the existing storage ring at the Australian Synchrotron.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA005
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TUPWA006	SIRIUS ACCELERATORS STATUS REPORT	1403
	A.R.D. Rodrigues, F.C. Arroyo, O.R. Bagnato, J.F. Citadini, R.H.A. Farias, J.G.R.S. Franco, L. Liupresenter, S.R. Marques, R.T. Neuenschwander, C. Rodrigues, R.M. Seraphim, O.H.V. Silva LNLS, Campinas, Brazil
	Sirius is a 3 GeV synchrotron light source that is being built by the Brazilian Synchrotron Light Laboratory (LNLS). The electron storage ring is based on a modified 5BA cell to achieve a bare lattice emittance of 0.27 nm.rad in a 518 m circumference ring that contains 20 straight sections of alternating 6 and 7 meters in length. The 5BA cell accommodates a thin permanent magnet high field (2 T) dipole in the center of the middle bend producing hard X-ray radiation (εc=12 keV) with a modest contribution to the total energy loss. In this paper we discuss the main achievements and issues for Sirius accelerators. Developments in beamlines are not discussed here.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA006
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TUPWA007	UPGRADED OPTICS FOR SIRIUS WITH IMPROVED MATCHING OF ELECTRON AND PHOTON BEAM EMITTANCES	1407
	L. Liu, N. Milas, A.H.C. Mukai, X.R. Resende, F.H. de Sá LNLS, Campinas, Brazil
	A new optics has been designed for Sirius with improved betatron function matching in the 6 meter-long low beta straight sections for insertion devices. Both horizontal and vertical betatron functions are set to 1.5 m in the center of the section, improving the matching of the electron and undulator photon beams. In addition, the horizontal beam stay clear has also been reduced allowing for small horizontal gap devices as well as the conventional small vertical gap ones. The new design optics has been optimized to the same previous performance regarding dynamic aperture and momentum acceptance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA007
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TUPWA008	Mixing and Space-Charge Effects In Free-Electron Lasers	1410
	E.A. Peter, A. Endler, F.B. Rizzato IF-UFRGS, Porto Alegre, Brazil A.P.B. Serbeto UFF, Niterói - RJ, Brazil
	Funding: This work was supported by CNPq and FAPERGS, Brazil, and by the Air Force Office of Scientific Research (AFOSR), USA, under the Grant No. FA9550-12-1-0438 Free-electron lasers are devices which efficiently convert the kinetic energy from a relativistic electron beam into electromagnetic radiation, amplifying an initial small sign. The present work revisits the subject of mixing, saturation and space-charge effects in free-electron lasers. Use is made of the compressibility factor, which proves to be a helpful tool in the related systems of charged beams confined by static magnetic fields. The compressibility allows to build a semi-analytical model and to perform analytical estimates of the elapsed time until the onset of mixing, which in turn allows to estimate the saturated amplitude of the radiation field. In addition, the compressibility helps to pinpoint space-charge effects and the corresponding transition from Compton to Raman regimes. The semi-analytical model and the particles simulations are compared, exhibiting a good agreement.* * E. Peter, A. Endler, F. B. Rizzato, and A. Serbeto, Phys. Plasmas 20, 123104 (2013). ** E. Peter, A. Endler, and F. B. Rizzato, Phys. Plasmas 21, 113104 (2014)
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA008
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TUPWA009	50 MeV Electron Linac with a RF Gun and a Thermoionic Cathode	1413
	A.S. Setty, A.S. Chauchat, D. Fasse, D. Jousse, P. Sirot Thales Communications & Security (TCS), Gennevilliers Cedex, France
	The low energy part of our pre injectors is made up of a 90 kV DC themoionic trioode gun, followed by a 500 MHz sub harmonic prebuncher and a 3 GHz prebuncher. We propose a new design for a 50 MeV linac with a RF gun *. this study will compare the beam dynamics simulations for the new design and for our previous pre injectors. * A. Setty et al. "Study of a RF gun with a Thermoionic Cathode", Proceeding IPAC 2014, Germany, Dresden, June 2014.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA009
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TUPWA011	Progress on the LUNEX5 project	1416
	M.-E. Couprie, C. Benabderrahmane, P. Berteaud, C. Bourassin-Bouchet, F. Bouvet, J.D. Bozek, F. Briquez, L. Cassinari, L. Chapuis, J. Da Silva, J. Daillant, Y. Dietrich, M. Diop, J.P. Duval, M.E. El Ajjouri, T.K. El Ajjouri, C. Herbeaux, N. Hubert, M. Khojoyan, M. Labat, P. Lebasque, N. Leclercq, A. Lestrade, A. Loulergue, P. Marchand, O. Marcouillé, J.L. Marlats, F. Marteau, C. Miron, P. Morin, A. Nadji, R. Nagaoka, F. Polack, F. Ribeiro, J.P. Ricaud, P. Rommeluère, P. Roy, G. Sharma, K.T. Tavakoli, M. Thomasset, M. Tilmont, S. Tripathi, M. Valléau, J. Vétéran, W. Yang, D. Zerbib SOLEIL, Gif-sur-Yvette, France S. Bielawski, C. Evain PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France B. Carré, D. Garzella CEA/DSM/DRECAM/SPAM, Gif-sur-Yvette, France X. Davoine CEA/DAM/DIF, Arpajon, France N. Delerue LAL, Orsay, France G. Devanz, C. Madec, A. Mosnier CEA/IRFU, Gif-sur-Yvette, France A. Dubois, J. Lüning CCPMR, Paris, France G. Lambert, V. Malka, A. Rousse, C. Thaury LOA, Palaiseau, France E. Roussel Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy C. Szwaj PhLAM/CERLA, Villeneuve d'Ascq, France
	LUNEX5 (free electron Laser Using a New accelerator for the Exploitation of X-ray radiation of 5th generation) aims at investigating the production of short, intense, coherent Free Electron Laser (FEL) pulses in the 40-4 nm spectral range. It comprises a 400 MeV superconducting Linear Accelerator for high repetition rate operation (10 kHz), multi-FEL lines and adapted for studies of advanced FEL schemes, a 0.4 - 1 GeV Laser Wake Field Accelerator (LWFA) for its qualification by a FEL application, a single undulator line enabling advanced seeding and pilot user applications. Different studies such as on two color FEL and R&D programs have been launched. A test experiment for the demonstration of 180 MeV LWFA based FEL amplification at 200 nm is under preparation in collaboration with the Laboratoire d’Optique Appliquée, thanks to a proper electron beam manipulation. Specific hardware is also under development such as a cryo-ready 3 m long undulator of 15 mm period.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA011
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TUPWA012	SOLEIL Status Report	1419
	A. Nadji, Y.-M. Abiven, F. Bouvet, P. Brunelle, A. Buteau, N. Béchu, L. Cassinari, M.-E. Couprie, X. Delétoille, C. Herbeaux, N. Hubert, N. Jobert, M. Labat, J.-F. Lamarre, P. Lebasque, A. Lestrade, A. Loulerguepresenter, P. Marchand, O. Marcouillé, J.L. Marlats, L.S. Nadolski, R. Nagaoka, P. Prigent, K.T. Tavakoli, M.-A. Tordeux, M. Valléau SOLEIL, Gif-sur-Yvette, France
	The 2.75 GeV synchrotron light source SOLEIL (France) delivers photons to 27 beamlines and 2 new ones are under construction. The commissioning of the Femtoslicing operation mode involving two beamlines is in progress. The uniform filling pattern is now available to users with a 500 mA stored beam current. The operation of the two canted and long beamlines ANATOMIX and Nanoscopium both using in-vacuum insertion devices (IDs) as a photon source has been raising challenges still under investigation. Upgrades of crucial subsystem equipment like magnet power supplies, storage ring RF input power couplers, and solid state amplifiers are continuing. New user requests for beam stability are under upgrade consideration. Other projects for the storage ring are ongoing such as the design and construction of new insertion devices, new multipole injection kicker, localised small and round photon beam production, as well as R&D on 500 MHz solid-state amplifiers. In parallel first studies for a future upgrade of the machine have been progressing.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA012
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TUPWA013	Linear and Nonlinear Optimizations for the ESRF Upgrade Lattice	1422
	N. Carmignani, L. Farvacque, S.M. Liuzzo, B. Nash, T.P. Perron, P. Raimondi, R. Versteegen, S.M. White ESRF, Grenoble, France
	The ESRF storage ring will be replaced in 2020 by a new hybrid multi bend achromat lattice with 134 pmrad equilibrium horizontal emittance. To determine the best working point, large scans of tunes and chromaticities have been performed, computing Touschek lifetime and dynamic aperture. From different working points, the multi-objective genetic algorithm NSGA-II has been used to optimize the nonlinear magnets values and some linear optics parameters. The analysis have been carried out on lattices with errors and corrections. The optimizations have produced lattices with longer lifetime and larger dynamic aperture for different working points with positive chromaticities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA013
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TUPWA014	Influence of errors on the ESRF Upgrade Lattice	1426
	S.M. Liuzzo, J.C. Biasci, N. Carmignanipresenter, L. Farvacque, G. Gatta, G. Le Bec, D. Martin, B. Nash, T.P. Perron, P. Raimondi, R. Versteegen, S.M. White ESRF, Grenoble, France
	To determine the tolerable alignment and magnetic errors for the ESRF upgrade, we study their influence on Touschek lifetime and dynamic aperture. The correction of each set of errors studied is performed with a commissioning-like procedure, from the search for a closed orbit to the correction of resonance driving terms. Each kind of error is studied independently for each relevant family of magnets. The tolerable values deduced from the analysis are within the practical limits. The impact of the measured and simulated survey errors is also considered, defining the position of the currently installed lattice as the one of least impact for the realignment of X-ray beamlines.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA014
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TUPWA016	Modeling of beam losses at ESRF	1430
	R. Versteegen, P. Berkvens, N. Carmignani, J. Chavanne, L. Farvacque, S.M. Liuzzo, B. Nash, T.P. Perron, P. Raimondi, K.B. Scheidt, S.M. White ESRF, Grenoble, France
	As the ESRF enters the second phase of its upgrade towards ultra low emittance, the knowledge of the beam loss pattern around the storage ring is needed for radiation safety calculations and for the new machine design optimization. A model has been developed to simulate the Touschek scattering and the scattering of electrons on residual gas nuclei in view of producing a detailed loss map of the machine. Results of simulation for the ESRF are presented and compared with real beam measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA016
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TUPWA017	Collimation scheme for the ESRF Upgrade	1434
	R. Versteegen, P. Berkvens, N. Carmignani, L. Farvacque, S.M. Liuzzo, B. Nash, T.P. Perron, P. Raimondi, S.M. White ESRF, Grenoble, France
	The ultra low emittance foreseen for the ESRF Upgrade will translate into a limited Touschek lifetime, increasing substantially the loss rate around the ring compared to the present machine. Consequently it becomes crucial to know the distribution of electron beam losses to optimize the radiation shielding and to protect the insertion devices from radiation damage. Such loss maps of the storage ring can be produced thanks to the simulation of the Touschek scattering process along the lattice. It is shown that about 80 % of the beam losses can be collimated in a few chosen locations only, keeping the resulting lifetime reduction smaller than 10 %.
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TUPWA018	Progress Report of the Berlin Energy Recovery Project BERLinPro	1438
	M. Abo-Bakr, W. Anders, K.B. Bürkmann-Gehrlein, A. Burrill, A.B. Büchel, P. Echevarria, A. Frahm, H.-W. Glock, A. Jankowiakpresenter, C. Kalus, T. Kamps, G. Klemz, J. Knobloch, J. Kolbe, J. Kühn, O. Kugeler, B.C. Kuske, P. Kuske, A.N. Matveenko, A. Meseck, R. Müller, A. Neumann, N. Ohm, K. Ott, E. Panofski, F. Pflocksch, D. Pflückhahn, J. Rahn, J. Rudolph, M. Schmeißer, O. Schüler, J. Völker HZB, Berlin, Germany
	Funding: Work supported by German Bundesministerium für Bildung und Forschung, Land Berlin, and grants of Helmholtz Association The Helmholtz Zentrum Berlin is constructing the Energy Recovery Linac Project BERLinPro on its site in Berlin Adlershof. The project is intended to expand the required accelerator physics and technology knowledge mandatory for the design, construction and operation of future synchrotron light sources. The project goal is the generation of a high current (100 mA), high brilliance (norm. emittance below 1 mm mrad) cw electron beamat 2~ps rms bunch duration or below. The planning phase of the project is completed and the design phase of most of the components is finished. Many of them have already been ordered. After some delay the construction of the building has started in February 2015. The status of the various subprojects as well as a summary of current and future activities will be given. Major project milestones and details of the project time line will be finally introduced.
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TUPWA019	A Canted Double Undulator System With a Wide Energy Range for EMIL	1442
	J. Bahrdt, H.-J. Bäcker, W. Frentrup, S. Gottschlich, C. Rethfeldt, M. Scheer, B. Schulz HZB, Berlin, Germany
	At BESSY II a canted double undulator system for the Energy Materials In-situ Laboratory EMIL is under construction. The energy regime is covered with two undulators, an APPLE II undulator for the soft and a cryogenic permanent magnet undulator CPMU17 for the hard photons. The layout and the performance of the undulators are discussed in detail. The minimum of the vertical betatron function is shifted to the center of the CPMU17. The neighboring quadrupoles and an additional quadrupole between the undulators control the vertical betatron function. Prior to the undulator installation a testing chamber with four movable scrapers has been implemented at the CPMU17 location. Utilizing the scrapers the new asymmetric lattice optics is tested and evaulated.
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TUPWA020	BNL ATF II Beamlines Design	1445
	M.G. Fedurin, Y.C. Jing, D. Stratakis, C. Swinson BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy. The Brookhaven National Lab. Accelerator Test Facility (BNL ATF) is currently undergoing a major upgrade (ATF-II). Together with a new location and much improved facilities, the ATF will see an upgrade in its major capabilities: electron beam energy and quality and CO2 laser power. The electron beam energy will be increased in stages, first to 100-150 MeV followed by a further increase to 500 MeV. Combined with the planned increase in CO2 laser power (from 1-100 TW), the ATF-II will be a powerful tool for Advanced Accelerator research. A high-brightness electron beam, produced by a photocathode gun, will be accelerated and optionally delivered to multiple beamlines. Besides the energy range (up to a possible 500 MeV in the final stage) the electron beam can be tailored to each experiment with options such as: small transverse beam size (<10 um), flat beam, short bunch length (<100 fs) and, combined short and small bunch options. This report gives a detailed overview of the ATF-II capabilities and beamlines configuration.
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TUPWA021	A New Method to Generate Ultrashort and Coherent Pulses of Short-Wavelength Synchrotron Radiation	1448
	S. Khan DELTA, Dortmund, Germany
	Funding: Work supported by the BMBF (contract 05K13PE3) A laser-based method to generate ultrashort pulses of synchrotron radiation in electron storage rings is coherent harmonic generation (CHG) using two undulators to produce coherent radiation at harmonics of the initial laser wavelength by microbunching. The bunching factor and thus the pulse intensity, however, decreases exponentially with increasing harmonic order. Echo-enabled harmonic generation (EEHG), proposed in 2009 as FEL seeding scheme*, can be used to produce short synchrotron radiation pulses at higher harmonics, but requires three undulators in a straight section. In this paper, a less space-consuming method based on seeding with intensity-modulated laser pulses is introduced, which also has the potential of significant bunching factors at high harmonics. * G. Stupakov, PRL 102 (2009), 074801.
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TUPWA022	Characterization and Optimization of Ultrashort and Coherent VUV Pulses at the DELTA Storage Ring	1452
	S. Khan, F.H. Bahnsen, M. Bolsinger, S. Hilbrich, M. Huck, M. Höner, C. Mai, A. Meyer auf der Heide, R. Molo, H. Rast, G. Shayeganrad, P. Ungelenk DELTA, Dortmund, Germany H. Huck DESY Zeuthen, Zeuthen, Germany
	Funding: Work supported by BMBF (05K13PE3 and 05K13PEC), DFG (INST 212/236-1 FUGG) and the Land NRW At DELTA, a 1.5-GeV synchrotron light source operated by the TU Dortmund University, a source for coherent and ultrashort vacuum-ultraviolet (VUV) and terahertz (THz) pulses is now in operation. The VUV source is based on a laser-induced energy modulation and coherent harmonic generation (CHG). A subsequently developing dip in the longitudinal electron distribution gives rise to coherent THz radiation. Recent results regarding the optimization of the laser-electron interaction and characterization of the CHG pulses are presented.
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TUPWA023	A Step Closer to the CW High Brilliant Beam with the ELBE SRF-Gun-II	1456
	R. Xiang, A. Arnold, P.N. Lu, P. Michel, P. Murcek, J. Teichert, H. Vennekate HZDR, Dresden, Germany
	In order to achieve the CW electron beam with a high average current up to 1 mA and a very low emittance of 1 μm, an improved superconducting photo-injector (ELBE SRF-Gun-II) has been installed and commissioned at HZDR since 2014. This new gun replaces the first 3.5-cell SRF gun (SRF-Gun-I) at the SC Linac ELBE. The RF performance of the niobium cavity has been evaluated, the beam parameters for low charge bunches have been measured, and the first beam has been guided into the ELBE beam line. The results agree with the simulation very well. The photocathode transfer system has been installed for the first high current beam test planned in 2015. However, the unexpected strong degradation on the cavity and also on the photocathode was found soon after the first photocathode exchange. In this contribution the results of the SRF-Gun-II commissioning and the latest experiment will be presented in detail.
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TUPWA025	Beam Heat Load Analysis with COLDDIAG: A Cold Vacuum Chamber for Diagnostics	1459
	R. Voutta, S. Casalbuoni, S. Gerstl, A.W. Grau, T. Holubek, D. Saez de Jauregui KIT, Eggenstein-Leopoldshafen, Germany R. Bartolini, M.P. Cox, E.C. Longhi, G. Rehm, J.C. Schouten, R.P. Walker DLS, Oxfordshire, United Kingdom M. Migliorati, B. Spataro INFN/LNF, Frascati (Roma), Italy
	The knowledge of the heat intake from the electron beam is essential to design the cryogenic layout of superconducting insertion devices. With the aim of measuring the beam heat load to a cold bore and understanding the responsible mechanisms, a cold vacuum chamber for diagnostics (COLDDIAG) has been built. The instrumentation comprises temperature sensors, pressure gauges, mass spectrometers and retarding field analyzers, which allow to study the beam heat load and the influence of the cryosorbed gas layer. COLDDIAG was installed in the storage ring of the Diamond Light Source from September 2012 to August 2013. During this time measurements were performed for a wide range of machine conditions, employing the various measuring capabilities of the device. Here we report on the analysis of the measured beam heat load, pressure and gas content, as well as the low energy charged particle flux and spectrum as a function of the electron beam parameters.
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TUPWA026	Simulation of Optical Transport Beamlines for High-quality Optical Beams for Accelerator Applications	1462
	J. Bödewadt, N. Ekanayake DESY, Hamburg, Germany
	High-quality optical beams play already an important role in the field of particle accelerators which will most probably become even more prominent in the view of laser-driven particle accelerators. Nowadays, optical transport systems are needed for particle generation in photo injectors, for particle acceleration in laser-driven plasma wakefield accelerators, for particle beam diagnostics such as synchrotron radiation monitoring systems, or for particle manipulation schemes e.g. for external seeding of free-electron lasers. For the latter case, also the photon beam transport to the user end-stations requires dedicated optical transport system. The utilized wavelengths range from the hard x-ray up to the far-infrared spectral range. Parameters like surface quality, polarization effects, damage thresholds in- and out-of-vacuum, mechanical stability, dispersion effect etc. need to be studied for the variaty of applications. Here, we present the simulation results of the optical transport beamline for the seeding setup at FLASH and give a comparision to our measurement results.
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TUPWA028	Simulation Results of the Beam Transport of Ultra-Short Electron Bunches in Existing Beam Transfer Lines to Sinbad	1466
	U. Dorda, R.W. Aßmann, K. Flöttmann, B. Marchetti, Y.C. Nie, J. Zhu DESY, Hamburg, Germany
	SINBAD, the upcoming accelerator R&D facility at DESY, will host multiple independent experiments on the production and acceleration of ultra-short bunches including plasma wakefield experiments. As a possible later upgrade the option to transport higher energy electrons (up to 800 MeV) or positrons (up to 400 MeV) from the existing DESY Linac 2 to the facility is studied. Though existing a possible connection using e.g. a part of the DESY synchrotron as a transfer line and other currently unused transfer-line, these machines were not designed for the desired longitudinal bunch compression and high peak current required by e.g. beam driven plasma wake-field experiments. Simulation results illustrate the modifications to the current layout that would have to be implemented and the corresponding achievable beam parameters are given.
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TUPWA029	ARES: Accelerator Research Experiment at SINBAD	1469
	B. Marchetti, R.W. Aßmann, C. Behrens, R. Brinkmann, U. Dorda, K. Flöttmann, J. Grebenyuk, M. Hüning, Y.C. Nie, H. Schlarb, J. Zhu DESY, Hamburg, Germany
	ARES is a planned linear accelerator for R&D for production of ultra-short electron bunches. It will be hosted at the SINBAD facility, at DESY in Hamburg*. The goal of ARES is to produce low charge (0.2-50pC), ultra-short (from few fs to sub-fs) bunches, with high arrival time stability (less than 10fs) for various applications, such as external injection for Laser Plasma Wake-Field acceleration**. The baseline layout of the accelerator foresees an S-band photo-injector which compresses low charge electron bunches via velocity bunching and accelerates them to 100 MeV energy. In the second stage, it is planned to install a third S-band accelerating cavity to reach 200 MeV as well as two X-band cavities: One for the linearization of the longitudinal phase space (subsequently allowing an improved bunch compression) and another one as a transverse deflecting cavity for longitudinal beam diagnostics. Moreover a magnetic bunch compressor is envisaged allowing to cut out the central slice of the beam*** or hybrid bunch compression. * R. Assmann et al., TUPME047, Proceedings of IPAC 2014. ** R. Assmann, J. Grebenyuk, TUOBB01, Proceedings of IPAC 2014. *** P. Emma et al., PRL 92 7 (2004).
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TUPWA030	Compression of an Electron-bunch by Means of Velocity Bunching at ARES	1472
	B. Marchetti, R.W. Aßmann, U. Dorda, J. Grebenyuk, J. Zhu DESY, Hamburg, Germany
	ARES is a planned linear accelerator for research and development in the field of production of ultra-short electron bunches. The goal of ARES is to produce low charge (0.2-50pC), ultra-short (from few fs to sub-fs) bunches, with improved arrival time stability (less than 10fs) for various applications, such as external injection for Laser Plasma Wake-Field acceleration. The ARES layout will allow to perform and compare different kind of conventional e-bunch compression techniques, such as pure velocity bunching*, hybrid velocity bunching (i.e. velocity bunching plus magnetic compression) and pure magnetic compression with the slit insertion**. This flexibility will allow to directly compare the different methods in terms of arrival time stability and local peak current. In this paper we present simulation results for the compression of an electron bunch with 0.5 pC charge. We compare the case of pure velocity bunching compression to the one of a hybrid compression using velocity bunching plus a magnetic compressor. * M. Ferrario et al., Phys. Rev. Lett. 104, 054801 (2010). ** P. Emma et al., PRL 92 7 (2004).
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TUPWA031	Compression of Train of Bunches with Ramped Intensity Profile at SPARC_LAB	1476
	B. Marchetti DESY, Hamburg, Germany A. Bacci Istituto Nazionale di Fisica Nucleare, Milano, Italy E. Chiadroni, M. Ferrario, R. Pompili INFN/LNF, Frascati (Roma), Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy
	The production and acceleration of train of bunches with variable spacing in the ps/sub-ps range having ramped intensity profile are interesting to drive a plasma wave in the so-called resonant Plasma Wake-Fields Acceleration (r-PWFA)*. At SPARC_LAB trains having a constant intensity profile have been produced for the first time by using a shaped photo-cathode laser combined with the use of the velocity bunching compression technique**,***,****. If the sub-bunches have ramped intensity, i.e. they have different charge density, the space charge force affects differently the development of the longitudinal phase space of each one of them during the compression. In this paper we present preliminary simulations for the compression of a ramped train of bunches. The differences between the beam dynamics for a train of bunches having constant intensity profile and the ramped train are underlined. We discuss also the possibility of properly tuning the shaping of the photocathode laser to balance the space charge effect. * SLAC-PUB-3528 ** M. Ferrario et al., Phys. Rev. Lett. 104, 054801 (2010). *** M. Ferrario et al. NIM A 637, S43-S46 (2011). **** E. Chiadroni et al., Rev. Sci. Instrum. 84, 022703
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TUPWA032	Progress in the Injector Upgrade of the LINAC II at DESY	1479
	Y.C. Nie, M. Hüning, C. Liebig, M. Schmitz DESY, Hamburg, Germany
	A new injection system is under development for the LINAC II at DESY to improve the reliability of the machine and mitigate the radiological problem due to electron losses at energy of hundreds of MeV. It consists of a 100 kV triode DC gun, a 2.998 GHz pre-buncher, a novel 2.998 GHz hybrid buncher, and the dedicated beam transport and diagnostic elements. As the key components, the pre-buncher and the hybrid buncher realize a two-stage velocity bunching process including the ballistic bunching and the phase space rotation. Therefore, they produce a certain number of well-bunched 5 MeV micro-bunches from the input 2 ns-50 ns electron pulse for the downstream LINAC II. The overall upgrade plan, developments of the critical components, as well as the latest beam test results will be reported.
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TUPWA033	Status of the Soft X-ray Free Electron Laser FLASH	1482
	M. Vogt, B. Faatz, J. Feldhaus, K. Honkavaara, S. Schreiber, R. Treusch DESY, Hamburg, Germany
	The superconducting free-electron laser FLASH at DESY routinely produces up to several thousand photon pulses per second with wavelengths in the soft X-ray and vacuum UV regime and with energies up to 0.5 mJ per pulse. In 2014 the assembly of a second undulator beamline, FLASH2, was finished. While recommissioning of the FLASH linac and the original FLASH1 beamline was finished already at the end of 2013, the commissioning of FLASH2 could only be started in early February 2014. Only a few weeks have been reserved for dedicated set up of FLASH2, and most of its commissioning has been performed parasitically during the FLASH1 user run. The first beam was extracted through the septum to the FLASH2 beamline on March 4th, 2014, and the first lasing of FLASH2 at a wavelength of about 40 nm was achieved on August 20th, while FLASH1 was lasing simultaneously with 250 bunches at 13.5 nm. We summarize here the status of the FLASH2 commissioning and the FLASH1 operation during its 5th user period.
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TUPWA034	Status of the Recommissioning of the Synchrotron Light Source PETRA III	1485
	R. Wanzenberg, M. Bieler, M. Ebert, L. Fröhlich, J. Keil, J. Klute, G. Kube, G.K. Sahoopresenter DESY, Hamburg, Germany
	At DESY the Synchrotron Light Source PETRA III has been extended in the North and East section of the storage ring to accommodate ten additional beam lines. The PETRA ring was converted into a dedicated synchrotron light source from 2007 to 2009. Regular user operation started in summer 2010 with a very low emittance of 1 nm at a beam energy of 6 GeV and a total beam current of 100 mA. All photon beamlines were installed in one octant of the storage ring. Nine straight sections facilitated the installation of insertion devices for 14 beam lines. Due to the high demand for additional beamlines the lattice of the ring was redesigned to accommodate 10 additional beamlines in the future. In a one year long shut-down two new experimental halls were built. The recommissioning of PETRA III started in February 2015. We are reporting the current status of synchrotron light source including the performance of the subsystems.
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TUPWA035	Progress in Optics Studies at FLASH	1488
	J. Zemella, T. Hellert, M. Scholz, M. Vogt DESY, Hamburg, Germany
	FLASH is the superconducting soft X-ray Free Electron Laser in Hamburg at DESY, Germany. Good control over the beam optics is a key aspect of the operation of a SASE FEL. In 2013 a second beam line, FLASH2, was assembled and the modifications necessary to feed the two beam lines were installed downstream of the FLASH linac. As reported before * we started a campaign of optics consolidation. We give an update on the progress of this effort and on results. * J. Zemella, T. Hellert, M.Scholz, M.Vogt, "Measurements of the Optical Functions at FLASH", Proc. of IPAC'14, TUPRO050.
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TUPWA036	Possibility of Longitudinal Bunch Compression in Petra III	1492
	I.V. Agapov XFEL. EU, Hamburg, Germany S.I. Tomin NRC, Moscow, Russia R. Wanzenberg DESY, Hamburg, Germany
	A scheme of short bunch production in storage rings using a longitudinally focusing insertion was presented in *. In this work we study the possibility of integrating such insertion into the PetraIII storage ring. In particular, we discuss possible optics solutions to integrate RF stations, chicane-type delay sections, and the undulators into existing ring geometry. * I. Agapov and G. Geloni, proc. FEL 2014.
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TUPWA037	Statistical Optimization of FEL Performance	1496
	I.V. Agapov, G. Geloni XFEL. EU, Hamburg, Germany I. Zagorodnov DESY, Hamburg, Germany
	Modern FEL facilities such as the European XFEL will serve large number of users, thus understanding and optimizing their performance parameters such as the output power is important. In this work we describe the statistical approach to such optimization under assumption that the possibility of modelling is limited by uncertainties. We present results of such statistical optimization of SASE radiation power for FLASH and discuss how the results of such empirical tuning can be fed back into the model used in simulations
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TUPWA038	Optics Compensation for Variable-gap Undulator Systems at FLASH	1499
	Ph. Amstutz, C. Lechner, T. Plathpresenter Uni HH, Hamburg, Germany S. Ackermann, J. Bödewadt, M. Vogt DESY, Hamburg, Germany
	Variable-gap undulator systems are widely used in storage rings and linear accelerators to generate soft- and hard x-ray radiation for the photon science community. For cases where the effect of undulator focusing significantly changes the electron beam optics, a compensation is needed in order to keep the optics constant in other parts of the accelerator. Since 2010, the free-electron laser (FEL) facility FLASH is equipped with two undulator sections along the same electron beamline. The first undulator is a variable-gap system used for seeding experiments, the second undulator is a fixed-gap system which serves the user facility with FEL radiation. Varying the gap in the first undulator will change the beam optics such that the FEL process in the second undulator is dramatically disturbed. For the correction of the beam optics an analytical model is used to generate feed forward tables which allows to make part of the beamline indiscernible for the subsequent sections. The method makes use of the implicit function theorem and can be used for any perturbation of the beam optics. Here, we present the method and its implementation as well as measurements performed at FLASH.
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TUPWA039	Transverse Gradient Undulator-Based High-Gain-FELs - a Parameter Study	1502
	A. Bernhard, V. Afonso Rodríguez, E. Burkard, A.-S. Müller, C. Widmann KIT, Karlsruhe, Germany
	Transverse gradient undulators (TGU) have recently been discussed as sources for High Gain Free Electron Lasers (FEL) driven by electron beams with an elevated energy spread as for example generated in storage rings or wakefield accelerators. In this contribution we present the results of a parameter study based on the one-dimensional TGU-FEL theory making realistic assumptions on the key parameters achievable for the transverse gradient undulator. We show for which parameter areas LWFA-driven TGU-FELs are virtually technically feasible today and which technical improvements would be required to employ the concept for a laboratory-scale X-Ray FEL.
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TUPWA042	Status of the Accelerator Physics Test Facility FLUTE	1506
	M.J. Nasse, A. Bernhard, I. Birkel, A. Borysenko, A. Böhm, S. Hillenbrand, N. Hiller, S. Höninger, S. Marsching, A.-S. Müller, R. Rossmanith, R. Ruprecht, M. Schuh, M. Schwarzpresenter, B. Smit, S. Walther, M. Weber, P. Wesolowski KIT, Karlsruhe, Germany R.W. Aßmann, M. Felber, K. Flöttmann, C. Gerth, M. Hoffmann, P. Peier, H. Schlarb, B. Steffen DESY, Hamburg, Germany R. Ischebeck, B. Keil, V. Schlott, L. Stingelin PSI, Villigen PSI, Switzerland
	A new compact versatile linear accelerator named FLUTE (Ferninfrarot Linac Und Test Experiment) is currently under construction at the Karlsruhe Institute of Technology (KIT). It will serve as an accelerator test facility and allow conducting a variety of accelerator physics studies. In addition, it will be used to generate intense, ultra-short THz pulses for photon science experiments. FLUTE consists of a ~7 MeV photo-injector gun, a ~41 MeV S-band linac and a D-shaped chicane to compress bunches to a few femtoseconds. This contribution presents an overview of the project status and the accompanying simulation studies.
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TUPWA043	Non-interferometric Spectral Analysis of Synchrotron Radiation in the THz regime at ANKA	1509
	J.L. Steinmann, M. Brosi, E. Bründermann, C.M. Caselle, E. Hertle, N. Hiller, B. Kehrer, A.-S. Müller, M. Schuh, M. Schwarzpresenter, P. Schönfeldt, P. Schütze KIT, Karlsruhe, Germany J.L. Hesler Virginia Diodes Inc., Charlottesville, USA
	Interferometry is the quasi-standard for spectral measurements in the THz- and IR-range. The frequency resolution, however, is limited by the travel range of the interferometer mirrors. Therefore, a resolution in the low megahertz range would require interferometer arms of about 100 m. As an alternative, heterodyne measurements provide a resolution in the Hertz range, an improvement of 6 orders of magnitude. Here we present measurements done at ANKA with a VDI WR3.4SAX, a mixer that can be tuned to frequencies from 220 GHz to 330 GHz and we show how the bunch filling pattern influences the amplitude of specific frequencies.
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TUPWA044	Test electron source for increased brightness emission by near band gap photoemission	1512
	S. Friederich, K. Aulenbacher IKP, Mainz, Germany
	Funding: Bundesministerium für Bildung und Forschung/Federal Ministry of Education and Research; Joint project HOPE A new photoemissive electron source is being built in order to make use of the reduction of ensemble temperature in near band gap photoemission. It will operate at up to 200 kV bias voltage with NEA GaAs photocathodes. High bunch charges will be investigated in pulsed mode with respect to the conservation of emittances at low energy excitations. High field gradients at the cathode surface will also allow further investigation of the field emission process of these photocathodes.
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TUPWA045	Further Investigations on the MESA injector	1515
	R.G. Heine, K. Aulenbacher, S. Friederich, C. Matejcek, F. Schlander IKP, Mainz, Germany
	Funding: work supported by the German Federal Ministery of Education and Research under the Cluster of Excellence "PRISMA" The MESA ERL to be build at Mainz in the next years is a multi turn recirculating linac with beam currents of up to 10 mA. The dynamic range of the beam currents demanded by the experiments is of at least two orders of magnitude. This is a special challenge for the layout design of an injector. In this paper we present the current status of the design of the injector linac called MAMBO (MilliAMpereBOoster).
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TUPWA046	Facility Upgrade at PITZ and First Operation Results	1518
	A. Oppelt, P. Boonpornprasert, A. Donat, J.D. Good, M. Groß, H. Huck, I.I. Isaev, L. Jachmann, D.K. Kalantaryan, M. Khojoyan, W. Köhler, G. Koss, G. Kourkafas, M. Krasilnikov, O. Lishilin, D. Malyutin, J. Meissner, D. Melkumyan, M. Otevřel, M. Penno, B. Petrosyan, S. Philipp, M. Pohl, Y. Renier, T. Rublack, B. Schöneich, J. Schultze, F. Stephan, F. Tonisch, G. Trowitzsch, G. Vashchenko, R.W. Wenndorff DESY Zeuthen, Zeuthen, Germany G. Asova INRNE, Sofia, Bulgaria M. A. Bakr Assiut University, Assiut, Egypt C. Hernandez-Garcia JLab, Newport News, Virginia, USA G. Pathak Uni HH, Hamburg, Germany D. Richter HZB, Berlin, Germany
	The Photo Injector Test facility at DESY, Zeuthen site (PITZ), develops, optimizes and characterizes high brightness electron sources for free electron lasers like FLASH and the European XFEL. In the last year, the facility was significantly upgraded by the installation of a new normal conducting radio- frequency (RF) gun cavity with its new waveguide system for the RF feed, which should allow stable and reliable gun operation, as required for the European XFEL. Other relevant additions include beamline modifications for improving the electron beam transport through the PITZ accelerator, extending the beam-based measurement capabilities, and preparing the installation of a plasma cell. Furthermore, the laser hutch was re-arranged in order to be able to house an additional, new photo cathode drive laser system which should be able to produce 3D ellipsoidal laser pulses to further improve the electron beam quality. This paper describes in detail the aforementioned facility upgrades and reports on the first operation experience with the new gun setup.
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TUPWA047	First Results Attained With the Quasi 3-D Ellipsoidal Photo Cathode Laser Pulse System at the High Brightness Photo Injector PITZ	1522
	T. Rublack, J.D. Good, M. Khojoyan, M. Krasilnikov, F. Stephan DESY Zeuthen, Zeuthen, Germany A.V. Andrianov, E. Gacheva, E. Khazanov, S. Mironov, A. Poteomkin, V. Zelenogorsky IAP/RAS, Nizhny Novgorod, Russia I. Hartl, S. Schreiber DESY, Hamburg, Germany E. Syresin JINR, Dubna, Moscow Region, Russia
	Funding: Funded by the German Federal Ministry of Education and Research (BMBF) project 05K10CHE in the framework of the German-Russian collaboration "Development and Use of Accelerator-Based Photon Sources". 3-D ellipsoidal photo cathode laser pulses are considered as the next step in optimization of photo injectors required for a successful operation of linac based free electron lasers. Beam dynamics simulations using such laser pulses compared to conventional cylindrical pulses have shown a significant improvement in electron beam emittance. In collaboration with the Institute of Applied Physics (Nizhny Novgorod, Russia) and the Joint Institute of Nuclear Research (Dubna, Russia) such a 3-D ellipsoidal laser pulse system has been developed and afterwards installed at the Photo Injector Test facility at DESY, Zeuthen site (PITZ). The pulse shaping is realized using the spatial light modulator technique. This allows very fine amplitude modulation within a laser pulse. The characterization of the shape of the laser pulses can be done by cross-correlation measurements. Using this method the ability to generate and measure quasi ellipsoidal laser pulses has been demonstrated. In this contribution the overall set-up, working principle and first results received with the new photo cathode laser system at PITZ will be reported.
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TUPWA048	Radiative Cooled Target for the ILC Polarized Positron Source	1526
	A. Ushakov University of Hamburg, Hamburg, Germany F. Dietrich, S. Riemann, T. Rublackpresenter DESY Zeuthen, Zeuthen, Germany P. Sievers CERN, Geneva, Switzerland
	Funding: Work supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Optimization", contract number 19XL7IC4 The target for the polarized positron source of the future International Linear Collider (ILC) is designed as wheel of 1 m diameter spinning with 2000 revolutions per minute to distribute the heat load. The target system is placed in vacuum since exit windows would not stand the load. In the current ILC design, the positron target is assumed to be water-cooled. Here, as an alternative, radiative cooling of the target has been studied. The energy deposition in the target is the input for ANSYS simulations. They include the temperature evolution as well as the corresponding thermo-mechanical stress in the target components. A principal design is suggested for further consideration.
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TUPWA051	Elettra Status and Future Prospects	1529
	E. Karantzoulis, A. Carniel, S. Krecic Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The operational status of the Italian 2.4/2.0 GeV third generation light source Elettra is presented together with possible future upgrades and a vision to its future.
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TUPWA052	Elettra 2.0 - The Next Machine	1532
	E. Karantzoulis Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	A next generation light source (ULS) to replace Elettra, the third generation Italian light source, is presented and discussed
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TUPWA053	Influence of a Non-uniform Longitudinal Heating on High Brightness Electron Beams for FEL	1535
	E. Roussel, E. Allaria, M.B. Danailov, G. De Ninno, S. Di Mitri, E. Ferrari, D. Gauthier, L. Giannessi, G. Penco Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	Laser-heater systems are essential tools to control and optimize high-gain free electron lasers (FELs), working in the x-ray wavelength range. Indeed, these systems induce a controllable heating of the energy spread of the electron bunch. The heating allows in turn to suppress longitudinal microbunching instabilities limiting the FEL performance. In this communication, we show that a long-wavelength energy modulation of the electron beam induced by the laser heater can persist until the beam entrance in the undulators, affecting the FEL emission process. This non-uniform longitudinal heating can be exploited to investigate the electron-beam microbunching in the linac, as well as to control the FEL spectral properties. Here, we present experimental, analytical and numerical studies carried out at FERMI.
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TUPWA054	The FERMI Seeded FEL Facility: Operational Experience and Future Perspectives	1538
	M. Svandrlik, E. Allaria, L. Badano, F. Bencivenga, C. Callegari, F. Capotondi, D. Castronovo, P. Cinquegrana, M. Coreno, R. Cucini, I. Cudin, G. D'Auria, M.B. Danailov, R. De Monte, G. De Ninno, P. Delgiusto, A.A. Demidovich, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, P. Finetti, P. Furlan Radivo, G. Gaio, D. Gauthier, F. Gelmetti, L. Giannessi, F. Iazzourene, M. Kiskinova, S. Krecic, M. Lonza, N. Mahne, C. Masciovecchio, M. Milloch, F. Parmigiani, G. Penco, L. Pivetta, O. Plekan, M. Predonzani, E. Principi, L. Raimondi, P. Rebernik Ribič, F. Rossi, E. Roussel, L. Rumiz, C. Scafuri, C. Serpico, P. Sigalotti, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Zangrando, M. Zangrando Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	FERMI is the seeded FEL user facility in Trieste, Italy, producing photons from the VUV to the soft X-rays with a high degree of coherence and spectral stability. Both FEL lines, FEL-1 and FEL-2, are now available for users, down to the shortest wavelength of 4 nm. We will report on the completion of the commissioning of the high energy FEL line, FEL-2, and on the operational experience for users, in particular those requiring specific FEL configurations, like two-colour experiments. We will also give a perspective on the improvements and upgrades which have been triggered by our experience and are aiming to maintain as well as to constantly improve the performance of the facility for our user community.
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TUPWA055	DAΦNE Gamma-Ray Factory	1542
	D. Alesini, S. Guiduccipresenter, C. Milardi, A. Variola, M. Zobov INFN/LNF, Frascati (Roma), Italy I. Chaikovska, Z.F. Zomer LAL, Orsay, France
	Gamma sources with high flux and spectral densities are the main requirements for new nuclear physics experiments to be performed in several worldwide laboratories with dedicated facilities. The presentation is focalized on a proposal of experiment of gamma photons production using Compton collisions between the DAΦNE electron beam and a high average power laser pulse, amplified in a Fabry-Pérot optical resonator. The calculations show that the resulting gamma beam source has extremely interesting properties in terms of spectral density, energy spread and gamma flux comparable (and even better) with the last generation gamma sources. The energy of the gamma beam depends on the adopted laser wavelength and can be tuned changing the energy of the electron ring. In particular we have analyzed the case of a gamma factory tunable in the 2-9 MeV range. The main parameters of this new facility are presented and the perturbation on the transverse and longitudinal electron beam dynamics is discussed. A preliminary accelerator layout to allow experiments with the gamma beam is presented with a first design of the accelerator optics.
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TUPWA056	New Gun Implementation and Performance of the DAΦNE LINAC	1546
	B. Buonomo, L.G. Foggetta, G. Piermarini INFN/LNF, Frascati (Roma), Italy
	A new electron gun system has been developed for DAΦNE LINAC, and put into operation since January 2014. Several elements of the system were upgraded, including a new grid pulser, an improved bias voltage system and a renewed cathode socket. The new LINAC gun has now a wider range of parameters, i.e. the emission pulse length spans from 1.4ns up to 40ns, while the better control of the grid and bias voltage allows a maximum peak current of 5A with a pulse repetition rate of 50 Hz. This paper describes the details of the pulser, the power supply, the socket, all the service components of the upgraded gun and its integration in the main LINAC control system. A report on the performance of the LINAC with the new gun will follow.
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TUPWA057	DAΦNE LINAC: Beam Diagnostics and Outline of the Last Improvements	1549
	B. Buonomo, L.G. Foggetta INFN/LNF, Frascati (Roma), Italy
	The LINAC of the DAΦNE complex is in operation since 1996, both as injector of the e+ e− phi-factory, and, since 2003, for the extraction of electron beam to the Beam Test Facility. In the last years, many improvements has been developed in different sub-systems of the LINAC, aiming at a wider, tunable range of beam parameters, in particular the pulse time width and the pulse charge. A long term measurement campaign has been recently started to characterize the LINAC performance after that many sub-systems has been overhauled and improved, starting from RF power (i.e. klystron substitution, modulator re-newing, RF driver layout, SLED tuning) as well as the timing system, magnets, cooling, vacuum, control system and energy/position diagnostics. This work reports the latest results on the optimization of the fully consolidated system.
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TUPWA058	Study of a C-band Harmonic RF System to Optimize the RF Bunch Compression Process of the SPARC Beam	1552
	A. Gallo, D. Alesini, M. Bellaveglia, M. Ferrario INFN/LNF, Frascati (Roma), Italy A. Baccipresenter, V. Petrillo, A.R. Rossi, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy F. Cardelli, L. Piersanti INFN-Roma1, Rome, Italy B. Marchetti DESY, Hamburg, Germany M. Rossetti Conti Universita' degli Studi di Milano & INFN, Milano, Italy
	The SPARC linac at the INFN Frascati Labs is a high brilliance electron source with a wide scientific program including production of THz and Thomson backscattering radiation, FEL studies and plasma wave acceleration experiments. The linac is based on S-band RF and consists in an RF Gun followed by 3 accelerating structures, while an energy upgrade based on 2 C-band accelerating structures is ready to be implemented. Short bunches are ordinarily produced by using the linear RF bunch compression concept. A harmonic RF structure interposed between the Gun and the 1st accelerating structure can be used to optimize the RF compression by a longitudinal phase space pre-correction, allowing to reach shorter bunches, a much more uniform current distribution and in general to control better the whole compression process. Here we report the results of numerical studies on the SPARC bunch compression optimization through the use of a harmonic cavity, and the design of a C-band RF system to implement it. The proposed system consists in a multi-cell SW cavity powered by a moderate portion of the total RF power spilled from the C-band power plant already installed for the linac energy upgrade.
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TUPWA059	Modeling of Photoemission and Electron Spin Polarization from NEA GaAs Photocathodes	1556
	O. Chubenko, A. Afanasev GWU, Washington, USA
	Funding: Work supported by The George Washington University and Thomas Jefferson National Accelerator Facility. Many nuclear-physics and particle-physics scientific laboratories, including Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (Jefferson Lab) which studies parity violation and nucleon spin structure, require polarized electron sources. At present, photoemission from strained GaAs activated to negative electron affinity (NEA) is a main source of polarized electrons. Future experiments at advanced electron colliders will require highly efficient polarized electron beams, which sets new requirements for photocathodes in terms of high quantum efficiency (QE) (>>1%) and spin polarization (~85%). Development of such materials includes modeling and design of photocathodes, material growth, fabrication of photocathodes, and photocathode testing. The purpose of the present work is to develop a semi-phenomenological model, which could predict photoemission and electron spin polarization from NEA GaAs photocathodes. Detailed Monte Carlo simulation and modeling of physical processes in photocathodes is important for optimization of their design in order to achieve high QE and reduce depolarization mechanisms. Electron-phonon interactions near the surface and influence of the presence of quantum heterostructures on the diffusion length are studied in depth. Simulation results will be compared to the experimental results obtained at Jefferson Lab and can be used to optimize the photocathode design and material growth, and thus develop high-polarization high-brightness electron source.
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TUPWA060	Design of Diffraction Limited Light Source Ring with Multi-bend Lattice on a Torus-knot	1560
	A. Miyamoto, S. Sasakipresenter HSRC, Higashi-Hiroshima, Japan
	We proposed a torus knot type synchrotron radiation ring in that the beam orbit does not close in one turn but closes after multiple turns around the ring. Currently, we are designing a new ring based on the shape of a (11, 3) torus knot for our future plan ‘HiSOR-II.’ This ring is mid-low energy light source ring with beam energy of 700 MeV. Recently some light source rings are achieving very low emittance that reaches a diffraction limited light by adopting a multi-bend scheme to the arc section of the ring. It is not difficult for low-mid energy VUV-SX light source ring because the electron beam less than 10 nmrad can provide the diffraction limited light in the energy less than 10eV. On the other hand, the multi-bend lattice demands many families of the magnets and spaces to place them, therefore it is difficult to achieve diffraction limited emittance for compact SR ring. However, for the torus-knot type accumulation ring, it is not difficult to realize such a low emittance. We present the details of the designing procedure and the specifications of the ultra-low emittance light source ring having innovatively odd shape.
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TUPWA061	Analyses of Light's Orbital Angular Momentum from Helical Undulator Harmonics	1563
	S. Sasaki, A. Miyamoto HSRC, Higashi-Hiroshima, Japan M. Hosaka, N. Yamamoto Nagoya University, Nagoya, Japan M. Katoh, T. Konomi UVSOR, Okazaki, Japan
	Funding: Partially supported by the Grant-in-Aid for Scientific Research, Japan Society for the Promotion of Science, and supported by the Joint Studies Program of the Institute for Molecular Science. The phenomenon of higher harmonic radiation from a helical undulator carrying orbital angular momentum (OAM)* attracts a great deal of attention because this novel property may be used as a new probe for synchrotron radiation science** that would be performed in a diffraction limited light source facility such as the APS-II. Although a diffraction limited x-ray source does not yet exist, the 750 MeV UVSOR-III is already a diffraction limited light source in the UV region. In this ring, a tandem-aligned double-APPLE undulator system similar to that in BESSY-II*** is installed for FEL and coherent light source experiments. Using this set-up, we observed spiral interference patterns between two different harmonic radiations with a scanning fiber multi-channel spectrometer and a CCD camera placed at the end of BL1U Beamline. By these measurements, various interference patterns such as single, double, and triple spirals were observed which concur with the theoretical prediction for every mode in the right or left circular polarization. The rotation of an interference pattern by rotating a polarizer was also observed. * S. Sasaki and I. McNulty, Phys. Rev. Lett. 100, 124801, 2008. ** M. VanVeenendaal and I. McNulty, Phys. Rev. Lett. 98, 157401 (2007). *** J. Bahrdt, et al., Phys. Rev. Lett. 111, 034801, 2013.
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TUPWA062	GaAs Photocathode Activation with CsTe Thin Film	1567
	M. Kuriki, Y. Seimiya, K. Uchida HU/AdSM, Higashi-Hiroshima, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	Funding: This work is partly supported by MEXT/JSPS KAKENHI (Grant-in-Aid for scientific research) 24654054. GaAs is an unique and advanced photocathode which can generate highly polarized and extremely low emittance electron beam. The photo-emission is possible up to 900nm wavelength. These advantages are due to NEA (Negative Electron Affinity) surface where the conduction band minimum is higher than the vacuum energy state. The NEA surface is artificially made with Cs-O/F evaporation on the cleaned GaAs surface, but the NEA surface is fragile, so that the emission is easily lost by poor vacuum environment and high emission density. NEA activation with any vital material is desirable. We found that the GaAs can be activated by CsTe thin film which is known as a vital photo-cathode material. The photo-electron emission spectrum extends up to 900 nm wavelength which corresponds to the band-gap energy of GaAs. The result strongly suggests that the surface becomes effectively NEA state by the CsTe thin film.
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TUPWA063	FEL Enhancement by Microbuch Structure Made with Phase-Space Rotation	1570
	M. Kuriki, Y. Seimiya HU/AdSM, Higashi-Hiroshima, Japan S. Chen, K. Ohmi, J. Urakawa KEK, Ibaraki, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan R. Kato ISIR, Osaka, Japan
	Funding: This work is partly supported by MEXT/JSPS KAKENHI (Grant-in-Aid for scientic research) 25390126, Japan. FEL is one of the ideal radiation source over the wide range of wavelength region with a high brightness and a high coherence. Many methods to improve FEL gain has been proposed by introducing an active modulation on the bunch charge distribution. The transverse-longitudinal phase-space rotation is one of the promising method to realize the density modulation as the micro-bunch structure. Initially, a beam density modulation in the transverse direction made by a mechanical slit, is properly transformed into the density modulation in the longitudinal direction by the phase-space rotation. The micro-bunch structure made with this method has a large tunability by changing the slit geometry, the beam line design, and the beam dynamics tuning. For FEL, enegy chirp made by the emittance exchange and chromaticity made by this chirp should be properly corrected. Simulation results and possible applications are discussed.
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TUPWA064	Study of Inherent Potential for Emittance Reduction at the SPring-8 Storage Ring	1573
	Y. Shimosaki JASRI/SPring-8, Hyogo-ken, Japan
	A design study for an upgrade project of the SPring-8, the SPring-8-II, is in progress, which is a full-scale major lattice modification. Besides the design study for the SPring-8-II, an inherent potential of achieving much higher brilliance than that of the present SPring-8 has been explored for the general evaluation. In this paper, the evaluation of the inherent potential for the SPring-8, not for the SPring-8-II, in terms of increasing the brilliance is discussed.
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TUPWA065	Generation of Multi-bunch Beam with Beam Loading Compensation by Using RF Amplitude Modulation in Laser Undulator Compact X-ray (LUCX)	1576
	M.K. Fukuda, S. Araki, Y. Honda, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan K. Sakaue, M. Washio RISE, Tokyo, Japan
	We have developed a compact X-ray source based on inverse Compton scattering between an electron beam and a laser pulse stacked in an optical cavity at Laser Undulator Compact X-ray (LUCX) accelerator in KEK. The accelerator consists of a 3.6 cell photo-cathode rf-gun, a 12cell standing wave accelerating structure and a 4-mirror planar optical cavity. Our aim is to obtain a clear X-ray image in a shorter period of times and the target flux of X-ray is 1.7x107 photons/pulse with 10% bandwidth at present. To achieve this target, it is necessary to increase the intensity of an electron beam to 500nC/pulse with 1000 bunches at 30 MeV. Presently, we have achieved the generation of 24MeV beam with total charge of 600nC in 1000bunches with beam-loading compensation by using the delta T method and the amplitude modulation of RF pulse. The bunch-by-bunch energy difference is within 1.3% peak to peak. We will report the results of the multi-bunch beam generation and acceleration in this accelerator. This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
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TUPWA066	Development of a High Average Power Laser for High Brightness X-ray Source and Imaging at cERL	1579
	A. Kosuge, T. Akagi, S. Araki, Y. Honda, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan R. Hajima, M. Mori, T. Shizuma JAEA, Ibaraki-ken, Japan R. Nagai JAEA/ERL, Ibaraki, Japan
	Funding: This study is supported by Photon and Quantum Basic Research Coordinated Development Program of MEXT, Japan. High brightness X-rays via laser-Compton scattering (LCS) of laser photons stored in an optical cavity by a relativistic electron beam is useful for many scientific and industrial applications such as X-ray imaging. The construction of compact Energy Recovery Linac (cERL) is now in progress at KEK to generate low-emittance and high-current electron beams. In order to demonstrate the generation of high brightness LCS X-rays, it is necessary to develop a high average power injection laser and an optical four-mirror ring cavity with two concave mirrors which is used to produce a small spot laser beam inside the cavity. In this presentation, we will show the result of the development of the high average laser system, the LCS X-rays generation, and the X-ray imaging.
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TUPWA067	Status of Higher Bunch Charge Operation in Compact ERL	1583
	T. Miyajima, K. Harada, Y. Honda, T. Miura, N. Nakamura, T. Obina, F. Qiu, H. Sakai, S. Sakanaka, M. Shimada, R. Takai, K. Umemori, M. Yamamoto KEK, Ibaraki, Japan R. Hajima, R. Nagai, N. Nishimori JAEA, Ibaraki-ken, Japan D. Lee KNU, Deagu, Republic of Korea
	In the KEK compact ERL (cERL), machine studies toward higher bunch charge operation is one of the most important issues. From January 2015 to April 2015, we carried out a higher bunch charge operation with an bunch charge of 0.5 pC for the experiment of laser compton scattering. After the study of space charge effect and optics tuning, we succeeded in the recirculation operation with the emittance, which was close to the design value. Moreover, a test operation in the injector section with the bunch charge of 7.7 pC was carried out as a preparation toward the recirculation operation with the average current of 10 mA.
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TUPWA068	Simulation Study of Beam Halo and Loss for KEK Compact ERL	1587
	O. Tanaka, T. Miyajimapresenter, N. Nakamura, S. Sakanaka, M. Shimada KEK, Ibaraki, Japan
	At the KEK Compact ERL (cERL) designed to operate at high-brilliance and high-current electron beams, the maximum averaged current was recorded at 6.5 muA for the beam energy of 20 MeV on March 2014 and should be increased up to 10 mA in a step-by-step manner in a few years. In order to increase the beam current by reducing the beam loss, we need to know the mechanism of the beam loss. For this purpose we investigate beam halo originated from characteristics and imperfections of an electron gun system, using the tracking code GPT (General Particle Tracer). The beam halo can be lost by the beam-pipe apertures and the collimators in the cERL beam line. In this paper, we will present the simulation results including the beam halo formation and the beam loss distribution along the beam line.
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TUPWA069	Simulation Study on Bunch Compression and Decompression for the Compact ERL	1591
	N. Nakamura, K. Harada, T. Miyajimapresenter, S. Sakanaka, M. Shimada, O. Tanaka KEK, Ibaraki, Japan
	Generation of THz coherent radiation (THz-CSR) is planned for the near future at the Compact Energy Recovery Linac (cERL) in KEK where the beam recirculation and energy recovery were already achieved in February 2014 and an experiment for generation of laser-Compton scattering X-rays (LCS-X) is being prepared to start in February 2015. To achieve a ultra-short bunch less than 100 fs for generation of the THz-CSR up to 5 THz, we have studied bunch compression and decompression in the cERL mainly by using a simulation code ELEGANT. In this study, off-crest acceleration in the main superconducting linac and non-zero R56 optics in the two arc sections are used and sextupole magnets are introduced into the two arc sections for correcting T566 of the arc sections. In this paper, we will present the simulation results and the requirements for the sextupole magnets including their number and layout.
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TUPWA070	CST Simulations of THz Cherenkov Smith-purcell Radiation from Corrugated Capillary	1594
	K. Lekomtsev, N. Terunumapresenter, J. Urakawa KEK, Ibaraki, Japan P. Karataev JAI, Egham, Surrey, United Kingdom A. Ponomarenko, A.A. Tishchenko MEPhI, Moscow, Russia
	Recent advances in generation of femtosecond pre-bunched beams have a potential to generate coherent THz radiation occurring via combination of Smith-Purcell radiation (SPR) and Cherenkov radiation (ChR) generated in a corrugated capillary. This mechanism was studied theoretically *. LUCX accelerator at High Energy Accelerator Research Organisation (KEK) has been upgraded by introducing fs Ti:Sa laser system and it is currently generating short tens of fs electron bunches **. In this report we present EM simulations of Ch.SPR generated in a corrugated channel in infinite dielectric and in a dielectric corrugated capillary. CST PIC solver is used as a simulation tool. It was earlier used for simulation of Transition radiation ***. Intensity dependencies of ChR and SPR peaks as functions of the capillary radius and the corrugation depth are compared with the theoretical investigation *. Output of THz radiation from the dielectric capillary with a radiation reflector is simulated. * A.A. Ponomarenko et. al, NIMB 309 (2013) 223-226. ** M. Fukuda et. al, NIMA 637 (2011) S67. *** K.V. Lekomtsev et. al, J. Phys.: Conf. Ser. 517, (2014) 012016.
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TUPWA071	Improvements of the Laser System for RF-Gun at SuperKEKB Injector	1598
	R. Zhang, T. Natsui, Y. Ogawa, M. Yoshida, X. Zhou KEK, Ibaraki, Japan
	For realizing higher charge and low emittance electron and positron beams in SuperKEKB, we have been making improvements in laser system for RF-gun. The difficulty in controlling thermomechanical distortions has been one of the most important factors for preserving high laser conversion efficiency of infrared-to-ultraviolet and operating at higher repetition rate. We demonstrated that efficient removal of waste heat can be realized by adopting Yb:YAG and copper bonding composite via Au-Sn solder. On the other hand, we proposed the novel design of the cascade laser configuration. Base on this, we can improve the quantum efficiency by utilizing other Yb ions doped crystals as active medium which are pumped by 1035 nm Yb:YAG laser. Excellent thermal management and high charge beams have been achieved by improvements of these two aspects. Additionally, in order to employ high duty ratio pump system and realize laser operation at high repetition rate, we investigated the laser operation in cryogenic environment. A perspective towards the next step experiment is also presented in this paper.
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TUPWA072	Coherent Thomson Scattering Radiation Generated by using PEHG	1601
	S. Chen, K. Ohmi, D. Zhoupresenter KEK, Ibaraki, Japan S. Huang PKU, Beijing, People's Republic of China
	In this paper, we present the coherent Thomson scattering of a long wavelength laser with ultrashort electron slices. The ultrashort electron slices are generated by the longitudinal bunch density modulation method of PEHG. Coherent radiation with ultrashort pulse length is generated in EUV regime by this method.
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