IPAC2011 - List of Keywords (laser)

Paper	Title	Other Keywords	Page
MOYCA01	Status Report on the Commissioning of the Japanese XFEL at SPring-8	undulator, acceleration, electron, FEL	21
	H. Tanaka RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	The Japanese XFEL at SPring-8, which was named SACLA (Spring-8 Angstrom Compact free electron LAser), was completed in FY2010. After RF full-power aging for about four months the beam commissioning of SACLA has been started since 21 February 2011. About one month later, in 23 March a design beam energy of 8 GeV was achieved and a spontaneous undulator radiation of 0.8 Angstrom was observed at the beam-line optical hutch by closing XFEL undulator gaps down to 5 mm in full-width. The beam commissioning has proceeded smoothly and since the middle of April we have entered to a tuning phase towards SASE lasing, which is at least one month ahead of schedule. This talk will report the beam commissioning overview of SACLA including SASE XFEL performance, key tuning-processes and critical issues for achieving the lasing.
	Slides MOYCA01 [37.840 MB]

MOODA03	First Characterization of a Fully Superconducting RF Photoinjector Cavity	cavity, cathode, linac, solenoid	41
	A. Neumann, W. Anders, R. Barday, A. Jankowiak, T. Kamps, J. Knobloch, O. Kugeler, A.N. Matveenko, T. Quast, J. Rudolph, S.G. Schubert, J. Völker HZB, Berlin, Germany P. Kneisel JLAB, Newport News, Virginia, USA R. Nietubyc The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock, Poland J.K. Sekutowicz DESY, Hamburg, Germany J. Smedley BNL, Upton, Long Island, New York, USA V. Volkov BINP SB RAS, Novosibirsk, Russia G. Weinberg FHI, Berlin, Germany I. Will MBI, Berlin, Germany
	As a first step towards a high brightness, high average current electron source for the BERLinPro ERL a fully superconducting photo-injector was developed by HZB in collaboration with JLab, DESY and the A. Soltan Institute. This cavity-injector ensemble is made up of a 1.6-cell superconducting cavity with a superconducting lead cathode deposited on the half-cell backwall. A superconducting solenoid is used for emittance compensation. This system, including a diagnostics beamline, has been installed in the HoBiCaT facility to serve as a testbed for beam dynamics studies and to test the combination SRF cavity and superconducting solenoid. This paper summarizes the characterization of the cavity in this configuration including Q measurements, dark current tests and field-stability analyses.
	Slides MOODA03 [10.343 MB]

MOODB03	Capture and Transport of the Laser Accelerated Ion Beams for the LIGHT Project	proton, solenoid, simulation, ion	59
	S.G. Yaramyshev, W.A. Barth, I. Hofmann, A. Orzhekhovskaya GSI, Darmstadt, Germany B. Zielbauer HIJ, Jena, Germany
	Funding: Work supported by EURATOM (IFK KiT Program) and HIC for FAIR An impressive advantage of Laser Ion Sources is an extremely high beam brilliance. The LIGHT project (Laser Ion Generation, Handling and Transport) is dedicated to the production of protons (ions), accelerated up to 10 MeV by using the GSI PHELIX laser at GSI, and injected into a conventional accelerator. A successful experimental campaign stimulated further investigation of the focusing, transport and collimation of the high energy and high brilliance proton beam. In addition to the advanced codes, describing the very early expansion phase of the proton-electron cloud, the versatile multiparticle code DYNAMION was implemented to perform beam dynamics simulations for different possible transport lines. Potentially transport lines compraises magnetic quadrupole lenses and/or solenoids for transverse beam focusing. A bunch rotation rf cavity decreasing the energy spread of the protons was included into the simulations. The results of the beam dynamics simulations are presented, as well as benchmarking activities with other codes. Further developments of the experimental test stand and the different possibilities of its integration to the GSI accelerators chain are discussed.
	Slides MOODB03 [2.185 MB]

MOPC014	RF Processing of L-band RF Gun for KEK-STF	cavity, gun, cathode, solenoid	92
	M. Kuriki, H. Iijima, Y.M. Masumoto HU/AdSM, Higashi-Hiroshima, Japan H. Hayano, H. Sugiyama, J. Urakawa, K. Watanabe KEK, Ibaraki, Japan G. Isoyama, R. Kato ISIR, Osaka, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan Y. Takahashi Sokendai, Ibaraki, Japan
	Funding: This work is supported by MEXT Quantum Beam Technology Program, KEK Promotion of collaborative research programs in universitie. KEK STF (Superconducting Test Facility) is established for developing super-conducting accelerator technology for ILC (International Linear Collider). At KEK-STF, accelerator operation with a beam loading is planned in 2013. An electron injector based on L-band Photo-cathode RF gun is now being developed. A L-band RF gun designed by DESY and fabricated by FNAL has been placed in KEK-STF and RF processing was carried out. The results of the RF processing and status of STF injector will be presented.

MOPC028	Beam Acceleration of DPIS RFQ at IMP	rfq, ion, ion-source, target	128
	Z.L. Zhang, X.H. Guo, Y. He, Y. Liu, S. Sha, A. Shi, L.P. Sun, H.W. Zhao IMP, Lanzhou, People's Republic of China R.A. Jameson, A. Schempp IAP, Frankfurt am Main, Germany M. Okamura BNL, Upton, Long Island, New York, USA
	Beam test of the direct plasma injection scheme (DPIS) is carried out successfully for the first time in China, by setting up a comprehensive test and research platform of RFQ and laser ion source. The C⁶⁺ beam is accelerated successfully, and the peak beam current reaches more than 6mA which is measured by a Faraday cup of unique structure. The RF power coupled into the RFQ cavity is also examined, and results reveal that it is the RF power of about 195kW that can produce the peak beam current.

MOPC060	Bunching-frequency Multiplication for a THz Pulse-train Photoinjector	electron, bunching, linac, acceleration	220
	Y.-C. Huang, F.H. Chao, C.H. Chen, K.Y. Huang NTHU, Hsinchu, Taiwan
	Funding: This work is supported by National Science Council under Contract NSC 99-2112-M-007 -013 -MY3. A THz-pulse-train photoinjector* employs a THz-pulse-train laser as its driver laser to generate a beam with a bunching frequency in the THz range. However a laser frequency is on the order of a few hundred THz. It is not possible to generate a beam from the pulse-train photoinjector with a bunching frequency exceeding the laser’s carrier frequency. In view of the strong demand for a compact x-ray free-electron laser (FEL), it is highly desirable to multiply the bunching frequency of the beam from a pulse-train injector to the x-ray frequencies. We propose to chirp the energy of the THz electron pulse train in an accelerator and compress the whole beam in a magnet to increase the electron bunching frequency. Our study shows a compression ratio or a bunching-frequency multiplication factor of a few tens is achievable from a properly designed magnetic chicane compressor. The bunching factor, however, is unfortunately degraded due to the energy chirp, emittance growth, and wake-field generation. In the conference, we will show that a bunching factor of a few ppm in the bunch-frequency multiplied beam is sufficient to build up the FEL power from a 10-time length reduced undulator. * Y. C. Huang, “Laser-beat-wave bunched beam for compact superradiance sources,” International Journal of Modern Physics B, Vol. 21 Issue 3/4, p277-286 (2007).

MOPC067	X-Band Test Station at Lawrence Livermore National Laboratory	electron, klystron, cathode, brightness	235
	R.A. Marsh, F. Albert, S.G. Anderson, C.P.J. Barty, G.K. Beer, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, T.L. Houck LLNL, Livermore, California, USA C. Adolphsen, A.E. Candel, T.S. Chu, E.N. Jongewaard, Z. Li, C. Limborg-Deprey, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou SLAC, Menlo Park, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. An X-band multi-bunch test station is being built at LLNL to investigate the science and technology paths required to boost the current mono-energetic gamma-ray (MEGa-Ray) brightness by orders of magnitude. The test station will consist of a 5.5 cell X-band RF photoinjector, single accelerator section, and beam diagnostics. Beam quality must be exceedingly high in order to produce narrow-bandwidth gamma-rays, requiring a robust state of the art photoinjector. The photoinjector will be a high gradient (200 MV/m peak surface field on the cathode) standing wave structure, featuring a dual feed racetrack coupler, elliptical irises, and an optimized first cell length. A solid-state Scandinova modulator will power a single SLAC XL4 11.424 GHz 50 MW klystron. RF distribution will allow for full powering of the photoinjector with the balance of the RF powering a single accelerator section so that the electron parameters can be measured. The status of the facility will be presented including commissioning schedule and first experiment plans. Future experimental programs pertinent to Compton scattering R&D, high gradient structure testing, and light source development will be discussed.

MOPC081	Pulsed Mode Operation and Longitudinal Parameter Measurement of the Rossendorf SRF Gun	gun, cavity, SRF, cathode	262
	J. Teichert, A. Arnold, H. Büttig, M. Justus, U. Lehnert, P. Michel, P. Murcek, Ch. Schneider, R. Schurig, R. Xiang HZDR, Dresden, Germany T. Kamps, J. Rudolph, M. Schenk HZB, Berlin, Germany I. Will MBI, Berlin, Germany
	Funding: The European Community-Research Infrastructure Activity under the FP7 program (EuCARD, contract number 227579) the German Federal Ministry of Education and Research grant 05 ES4BR1/8. The Rossendorf SRF gun with a 3 1/2 cell cavity has been operated since 2007. It has produced CW beam with the electron energy of 3 MeV and the average current up to 16 μA. The electron beam of the gun has successfully injected the ELBE superconducting linac since 2010. The Nb cavity has shown constant quality during the operation and for the Cs2Te photocathode life time of months could be obtained. Recently the gun started to run in the pulsed mode with higher gradient. The longitudinal parameters have been measured in this mode. The dark current arose from the high gradient is studied. The main field emission source has been found to be the half cell. Meanwhile, two modified 3+1/2 cell niobium cavities have been fabricated and tested in Jlab. In this paper the new status of the SRF gun will be presented, and the latest results of the beam experiments will be discussed.

MOPC145	Recent Progress on the Technical Realization of the Bunch Phase Timing System BuTiS	controls, cavity, diagnostics, status	418
	B. Zipfel, P. Moritz GSI, Darmstadt, Germany
	A high precision phase synchronous clock distribution system is mandatory for generating local RF reference signals in an accelerator complex. The dedicated Bunch Timing System (BuTiS) at GSI performs this function. The accuracy of the realized installation under rough ambient conditions is presented. Procedures for calibration and standardization aspects of system modules are pointed out. Hardware as well as software interfaces of the system are described. The interfacing between GPS and BuTiS are explained.

MOPC146	Development of Timing Distribution System with Femto-second Stability	feedback, linac, controls, acceleration	421
	T. Naito, K. Ebihara, S. Nozawa, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan M. Amemiya AIST, Tsukuba, Japan
	A timing distribution system with femto-second stability has been developed for the RF synchronization of accelerator and the laser synchronization of the pump-probe experiments. The system uses a phase stabilized optical fiber(PSOF) and an active fiber length stabilization. The PSOF has 5 ps/km/degC of the temperature coefficient. The active fiber length stabilization uses the phase detection of the round-trip sinusoidal wave and the fiber stretcher for the compensation of the fiber length. In this paper, we present the test results on a 500 m long signal distribution. The preliminary results of the timing stability are 20 fs at several minutes and 100 fs at four days, respectively.

MOPC148	Optical Clock Distribution System at the ALICE Energy Recovery Linac	pick-up, electron, FEL, feedback	427
	T.T. Ng, S.P. Jamison STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Highly stable clock distribution across future light sources is important for the synchronisation of beam generation, manipulation and diagnostics with photon experiments. Optical fibre technology can be used to combat the stability challenges in distributing clock signals over long distances with coaxial cable. We report here on the status of the optical clock distribution system installed on the ALICE energy recovery linac which uses the propagation of ultra-short optical pulses to carry the clock signal. We also present the characterisation of a beam arrival monitor suitable using <40 pC bunch charges and 7 mW, sub-100 fs distributed clock pulses.

MOPC150	High Charge PHIN Photo Injector at CERN with Fast Phase Switching within the Bunch Train for Beam Combination	cathode, vacuum, gun, bunching	430
	M. Divall Csatari, A. Andersson, B. Bolzon, E. Bravin, E. Chevallay, A.E. Dabrowski, S. Döbert, V. Fedosseev, C. Heßler, T. Lefèvre, S. Livesley, R. Losito, O. Mete, M. Olvegård, M. Petrarca, A. Rabiller CERN, Geneva, Switzerland A. Drozdy BUTE, Budapest, Hungary D. Egger EPFL, Lausanne, Switzerland
	The high charge PHIN photo-injector was developed within the frame of the European CARE program to provide an alternative to the drive beam thermionic gun in CTF3 (CLIC Test Facility) at CERN. In PHIN 1908 bunches are delivered with bunch spacing of 1.5 GHz and 2.33 nC charge per bunch. Furthermore the drive beam generated by CTF3 requires several fast 180 deg phase-shifts with respect to the 1.5 GHz bunch repetition frequency in order to allow the beam combination scheme developed at CTF3. A total of 8 sub-trains, each 140 ns long and shifted in phase with respect to each other, have to be produced with very high phase and amplitude stability. A novel fiber modulator based phase-switching technique developed on the laser system provides this phase-shift between two consecutive pulses much faster and cleaner than the base line scheme, where a thermionic electron gun and sub-harmonic bunching are used. The paper describes the fiber-based switching system and the measurements verifying the scheme. Stability measurements are presented for the phase-coded system. The paper also discusses the latest 8nC charge production and cathode life-time studies on Cs2Te.

MOPC154	RF Photo Gun Stability Measurement at PITZ	gun, feedback, cavity, electron	442
	I.I. Isaev, H.-J. Grabosch, M. Gross, L. Hakobyan, Ye. Ivanisenko, G. Klemz, W. Köhler, M. Krasilnikov, M. Mahgoub, D. Malyutin, A. Oppelt, M. Otevřel, B. Petrosyan, S. Rimjaem, F. Stephan, G. Vashchenko, S. Weidinger, R.W. Wenndorff DESY Zeuthen, Zeuthen, Germany G. Asova INRNE, Sofia, Bulgaria M. Hoffmann, H. Schlarb DESY, Hamburg, Germany M.A. Khojoyan YerPhI, Yerevan, Armenia D. Richter HZB, Berlin, Germany A. Shapovalov NRNU MEPHI, Moscow, Russia I.H. Templin, I. Will MBI, Berlin, Germany
	The stability of the RF phase in the RF photo injector gun is one of the most important factors for the successful operation of linac based free-electron lasers. Instabilities in the RF launch phase can significantly reduce the beam quality. Investigation on the dependence of different gun parameters and selection of optimal conditions are required to achieve high RF gun phase stability. The phase stability of the RF field is measured using the phase scan technique. Measurements were performed for different operating conditions at the Photo Injector Test facility at DESY, location Zeuthen (PITZ). Obtained stability measurement results will be presented and discussed.

MOPO018	Active Beam Current Stabilization in the Cornell ERL Prototype Injector	feedback, gun, cavity, cathode	523
	F. Löhl, P. Szypryt CLASSE, Ithaca, New York, USA
	In order to operate the Cornell ERL prototype injector at beam currents beyond 10 mA, the beam current has to be highly stable. The reason is that fast beam current fluctuations generate transient effects in the DC gun voltage as well as in the fields of subsequent superconducting cavities, which can lead to excessive beam loss or to trips of subsystems. Therefore, a feedback scheme was developed which uses the signal of a beam current monitor as an input, and applies appropriate corrections to a Pockels cell installed within the laser path of the photo-injector laser. In this paper, high current results achieved with this feedback scheme are presented.

MOPO023	Laser-based Alignment System at the KEKB Injector Linac	alignment, linac, vacuum, injection	529
	M. Satoh, N. Iida, T. Suwada KEK, Ibaraki, Japan K. Minoshima, S. Telada AIST, Tsukuba, Japan
	A laser-based alignment system is under development at the 500-m-long KEKB injector linac. The original system was designed and constructed more than thirty-years ago, and thus, we are revisiting our alignment system because the previous alignment system has become too obsolete. The new alignment system is again strongly required for the next generation SuperKEKB project. The new laser alignment system is similar to the previous one, which comprises a helium-neon laser and quadrant photodetectors installed in vacuum light pipes. A girder displacement of the accelerating structure can be precisely measured in the direction of the laser-ray trace, where the laser light must stably propagate up to 500-m downstream without any orbital and beam-size fluctuation. We tested the laser-ray propagation and the stability along a 100-m-long beam line under a vacuum condition of 0.1-1 Torr. In this paper, we will report the system description and test results in detail.

MOPO025	Experimental Study on New Laser-based Alignment System utilizing a Sequential Three-point Method at the KEKB Injector Linac	alignment, linac, focusing, factory	532
	T. Suwada, M. Satoh KEK, Ibaraki, Japan K. Minoshima, S. Terada AIST, Tsukuba, Japan
	A new laser-based alignment system is under development in order to precisely align accelerator components along an ideal straight line at the 600-m-long KEKB injector linac. A well-known sequential three-point method with Fresnel lenses and a CCD camera is revisited in a preliminary design of the new alignment system. The new alignment system is strongly required in order to stably accelerate high-brightness electron and positron beams with high bunch charges and also to keep the beam stability with higher quality towards the Super B-factory at KEK. A new laser optics has been developed and the laser propagation characteristics has been systematically investigated at a 200-m-long straight section at atmospheric pressure. In this report, the preliminary experimental results are reported along with the basic design of the new laser-based alignment system.

MOPO031	Alignment of theTPS Front-End Prototype	alignment, synchrotron, survey, synchrotron-radiation	550
	C.K. Kuan, Y.T. Cheng, W.Y. Lai, I.C. Sheng, T.C. Tseng, H.Y. Yan NSRRC, Hsinchu, Taiwan J.-R. Chen National Tsing Hua University, Hsinchu, Taiwan
	The Taiwan Photon Source (TPS) is a 3-GeV third-generation source of synchrotron radiation with beam current 500 mA stored in the storage ring. A front end allows intense synchrotron light generated in the storage ring to pass through to a beamline. Most heat load of the synchrotron light is removed in the front ends to protect the beamline components. Alignment of front-end components becomes important to prevent damage from the large heat load. Because of the many front ends and the brief period of installation, the alignment work should be easy, quick and reliable. Using a shim method, the adjustable degrees of freedom are decreased from six to two. This adjustment work becomes easier and quicker. The alignment of a front-end prototype is described here.

MOPO033	Design and Development of a Laser Positioning System for TPS Magnets Alignment Inspection during the Installation on a Girder	quadrupole, sextupole, alignment, lattice	556
	Chen, M. L. Chen, H.C. Ho, K.H. Hsu, W.Y. Lai, S.Y. Perng, Y.L. Tsai, T.C. Tseng, H.S. Wang NSRRC, Hsinchu, Taiwan J.-R. Chen National Tsing Hua University, Hsinchu, Taiwan
	A novel optical inspection architecture is designed and developed for positioning the TPS (Taiwan Photon Source) quadrupole and sextupole magnets on the girder within 30 um. This positioning system is a laser-based scheme consists of two laser position sensing devices (PSD) and two granite blocks as the standard reference of magnets. The laser position sensing device (PSD) is mounted on an adjustable circular steel module and the module is installed in a granite block. With the PSD position being adjusted and corrected, the PSD module center can be identical to the ideal pole position of magnets on the girder within 10um. The Laser ray is also adjusted and aligned according to the ideal reference line of magnets. Finally the granite blocks are replaced with the quadrupole and sextupole magnets at installation, the assembling error of magnets can be detected from the PSD module. This paper describes the detail of the system development and testing results.

MOPO034	From Survey Alignment toward Auto-alignment for the Installation of the TPS Storage Ring Girder System	survey, alignment, photon, controls	559
	T.C. Tseng, Chen, M. L. Chen, H.C. Ho, K.H. Hsu, W.Y. Lai, C.J. Lin, H.M. Luo, S.Y. Perng, P.L. Sung, Y.L. Tsai, H.S. Wang NSRRC, Hsinchu, Taiwan J.-R. Chen National Tsing Hua University, Hsinchu, Taiwan
	The TPS (Taiwan Photon Source) project is now under civil construction. The whole building is constructed half underground and 12m deep compared to the TLS due to the stability consideration, so the survey and alignment works are quite confined and difficult. For positioning the magnets precisely and quickly, a high accuracy auto-tuning girders system combined with survey network procedures were established to accomplish the installation tasks. The position data from the survey network will define a basis for the motorized girder system to auto-tune and improve the accuracy. A mockup of one twenty-fourth section (one cell) had been installed at NSRRC for interface examination and further testing. In this paper, the procedures from the traditional survey network to auto-aliment system design and algorithm are described. Meanwhile, a preliminary testing result is also included.

MOPO037	Concept of Femtosecond Timing and Synchronization Scheme at ELBE	electron, controls, status, pick-up	565
	M. Kuntzsch, A. Büchner, M. Gensch, A. Jochmann, T. Kirschke, U. Lehnert, F. Röser HZDR, Dresden, Germany M.K. Bock, M. Bousonville, M. Felber, T. Lamb, H. Schlarb, S. Schulz DESY, Hamburg, Germany
	The Radiation Source ELBE at Helmholtz-Zentrum Dresden-Rossendorf is undergoing an extension to offer capacity for various applications. The extension includes the setup of a THz-beamline with a dedicated laboratory and a beamline for electron-beam - high-power laser interaction. The current synchronization scheme offers stability on the picoseconds level. For pump-probe experiments using optical lasers, the desired synchronization between the pump and the probe pulse should be on the femtosecond scale. In the future there will be an optical synchronization system with a pulsed fiber laser as an optical reference. The laser pulses will be distributed over stabilized fiber links to the remote stations. It is planned to install EOM-based beam arrival time monitors (BAMs) in order to monitor the bunch jitter and to establish a beam-based feedback to reduce the jitter. Besides that, the timing system has to be revised to generate triggers for experiments with low repetition rate, two electron guns (thermionic DC, superconducting RF) and several lasers. The Poster will show the possible layout of the future Timing and Synchronization System at ELBE.

MOPO040	RF Reference Distribution for the Taiwan Photon Source	synchrotron, controls, diagnostics, LLRF	571
	K.H. Hu, Y.-T. Chang, J. Chen, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, S.Y. Hsu, C.H. Kuo, D. Lee, C.-Y. Liao, C.Y. Wu NSRRC, Hsinchu, Taiwan
	Taiwan Photon Source (TPS) is a low-emittance 3-GeV synchrotron light source with circumference of 518.4 m which is being under construction at National Synchrotron Radiation Research Center (NSRRC) campus. Low noise 500 MHz master oscillator and novel fiber based CW RF reference distribution system will be employed to take advantages of advanced technology in this field and deliver better performance. The preliminary test of the prototype system is summarized in this report.

MOPO042	Photonic Crystal Fibre Laser for Electron Beam Emittance Measurement*	emittance, electron, diagnostics, extraction	577
	L. Corner, L.J. Nevay, R. Walczak Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	We discuss the recent progress in the development of a high repetition rate, high energy fibre laser for intratrain laser-wire scans of transverse electron beam sizes. A commercial fibre laser (1uJ, 6.49MHz) is amplified in rod type photonic crystal fibre using a burst mode format, which has the advantage of allowing us to exploit very high transient gain while reducing the heat load deposited in the amplifier. The amplified pulses are over 180uJ spaced at 154ns, suitable for intratrain scanning at the ATF2. The spatial beam quality is excellent (M2 = 1.07), indicating that it will be possible to focus the laser to a spot size of ~ λ, enabling us to reach high intensities. The amplified pulse duration is 200ps, which can be compressed to less than the electron bunch length to increase the laser-wire signal to noise ratio. The performance of the laser system is analysed with respect to the demands of the laser-wire experiment.

MOPO043	Applications of Lasers to Accelerator Physics at SSRL	gun, cathode, photon, electron	580
	D.L. Robinson Cal Poly, San Luis Obispo, California, USA W.J. Corbett SLAC, Menlo Park, California, USA
	Recent advances in accelerator physics and SR research have generated the need for high-power lasers in the SPEAR3 accelerator complex. On the injector side, two lasers are being used to test different photocathode materials and to provide photo-assisted emission from the standard dispenser cathode RF gun. For the storage ring, both a TiSa oscillator and a fiber laser locked to the RF master oscillator have been used to characterize short-pulse electron bunches in cross-correlation experiments. These lasers are also used in SR experiments for pump-probe characterization of materials. In this paper we review the laser-based systems, preliminary results and outlook for the future.

MOPO044	Bunch Length Measurements in Low-Alpha Mode at SPEAR3 with First Time-Resolved Pump/Probe Experiments*	photon, synchrotron, single-bunch, radiation	583
	J.S. Wittenberg, A. Lindenberg, A. Miller Stanford University, Stanford, California, USA W.J. Corbett, L. Wang SLAC, Menlo Park, California, USA
	Funding: Work sponsored by U.S. Department of Energy Contract DE-AC03-76SF00515, Office of Basic Energy Sciences and SLAC Laboratory Directed Research Development funds (LDRD) The SPEAR3 synchrotron light source can be operated in low-alpha mode to generate x-ray pulse durations of order 1ps, well below streak camera resolution limits yet accessible by laser/sr cross-correlation measurements. Initial CC tests performed with a 50fs TiSa laser, frequency doubling BBO, photodiode and lock-in amplifier resolved bunch lengths down to about 6ps rms with 85uA single-bunch current. By reconfiguring the experimental setup to utilize a fiber laser, sum frequency generation and single photon counter it is now possible to measure profiles in the 1ps rms range with only 5uA single-bunch current. In this paper we report on the most recent measurements, simulations, modeling efforts and prospects for further improvement.

TUZA01	Commissioning and Initial Operation of FERMI@Elettra	FEL, electron, photon, undulator	918
	S. Di Mitri, E. Allaria, R. Appio, L. Badano, S. Bassanese, F. Bencivenga, A.O. Borga, M. Bossi, E. Busetto, C. Callegari, F. Capotondi, K. Casarin, D. Castronovo, P. Cinquegrana, D. Cocco, M. Cornacchia, P. Craievich, R. Cucini, I. Cudin, G. D'Auria, M.B. Danailov, R. De Monte, P. Delgiusto, A.A. Demidovich, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, S. Ferry, V. Feyer, L. Fröhlich, P. Furlan Radivo, G. Gaio, F. Gelmetti, L. Giannessi, R. Gobessi, R. Ivanov, E. Karantzoulis, M. Kiskinova, M. Lonza, A.A. Lutman, C. Masciovecchio, R.H. Menk, M.M. Milloch, M.M. Musardo, I. Nikolov, S. Noe, F. Parmigiani, L. Pavlovič, E. Pedersoli, G. Penco, M. Petronio, M. Predonzani, E. Principi, E. Quai, G. Quondam, F. Rossi, L. Rumiz, C. Scafuri, C. Serpico, P. Sigalotti, C. Spezzani, M. Svandrlik, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Wang, M. Zaccaria, D. Zangrando ELETTRA, Basovizza, Italy M. Alagia, A. Kivimaki, M. Zangrando, M. de Simone IOM-CNR, Trieste, Italy L. Avaldi, P. Bolognesi, M. Coreno, P. O’Keeffe CNR - IMIP, Trieste, Italy M. Dal Forno DIEIT, Trieste, Italy G. De Ninno, S. Spampinati University of Nova Gorica, Nova Gorica, Slovenia M. Devetta, T. Mazza, P. Piseri Università degli Studi di Milano, Milano, Italy E. Ferrari Università degli Studi di Trieste, Trieste, Italy S. Stranges Università di Roma "La Sapienza", Roma, Italy
	Funding: Work was supported in part by the Italian Ministry of University and Research under grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3. This article describes the design goals of FERMI@Elettra, reports on the goals achieved so far and shows how the facility development has been driven by the new research frontier of ultra-fast, extreme ultra-violet and soft X-ray science. The commissioning phases and first experience with user pilot experiments are presented and discussed.
	Slides TUZA01 [13.401 MB]

TUZA02	sFLASH - Present Status and Commissioning Results	undulator, electron, FEL, radiation	923
	V. Miltchev, S. Ackermann, A. Azima, J. Bödewadt, F. Curbis, M. Drescher, E. Hass, Th. Maltezopoulos, M. Mittenzwey, J. Rönsch-Schulenburg, J. Roßbach, R. Tarkeshian Uni HH, Hamburg, Germany H. Delsim-Hashemi, K. Honkavaara, T. Laarmann, H. Schlarb, S. Schreiber, M. Tischer DESY, Hamburg, Germany R. Ischebeck PSI, Villigen, Switzerland S. Khan DELTA, Dortmund, Germany
	The free-electron laser in Hamburg (FLASH) was previously being operated in the self-amplified spontaneous emission (SASE) mode, producing photons in the XUV wavelength range. Due to the start-up from noise the SASE-radiation consists of a number of uncorrelated modes, which results in a reduced coherence. One option to simultaneously improve both the coherence and the synchronisation between the FEL-pulse and an external laser is to operate FLASH as an amplifier of a seed produced using high harmonics generation (HHG). An experimental set-up - sFLASH, has been installed to test this concept for the wavelengths below 40 nm. The sFLASH installation took place during the planed FLASH shutdown in the winter of 2009/2010. The technical commissioning, which began in the spring of 2010, has been followed by seeded-FEL commissioning, FEL-characterisation and pilot experiments. In this contribution the present status and the sFLASH commissioning results will be discussed.
	Slides TUZA02 [4.125 MB]

TUPC009	The Recent JINR Advances in Technology Development on Linear Accelerators	electron, radiation, FEL, cryomodule	1006
	G. Shirkov, N. Balalykin, A. Dudarev, E. Syresin, G.V. Trubnikov, Yu.A. Yulian JINR, Dubna, Moscow Region, Russia E. Khazanov IAP/RAS, Nizhny Novgorod, Russia
	JINR experts take part in a few ILC related projects including photo injector prototype, participation in design and construction of cryomodules, RND on design of a new version of superconducting niobium resonator, laser metrology, etc. Some new results of this activity as well as recent data of ILC siting investigations in the Dubna region are presented.

TUPC010	Status of the Manufacturing of Accelerating Structures for LINACs	linac, vacuum, controls, extraction	1009
	F.M. Mirapeix, J. Añel, J. Castillo, A. Ortiz HTS, Mendaro, Spain X. Aldalur, J. Amores, A. Urzainki DMP, Mendaro, Spain
	Funding: HTS, DMP, ZEHATZ, CERN Particle accelerators need ongoing development in the state of the art of the field: high-quality manufacturing of accelerating structures, PETS, but also drift tubes, bunchers, high-power couplers, alignment systems, precision test stands, etc. They also require engineering projects in the range of mechatronics, thermodynamics, microwaves, ultra high vacuum, cryogenics, joining techniques, high precision manufacturing, 3D high precision scanning, etc. HTS together with DMP are actually working on all this fronts. In this paper, the actual status of the manufacturing capabilities concerning some accelerating structures will be described.

TUPC031	Advanced Research Electron Accelerator Laboratory Based on Photocathode RF Gun	gun, electron, emittance, controls	1066
	B. Grigoryan, G.A. Amatuni, V.S. Avagyan, A. Grigoryan, M. Ivanyan, V.G. Khachatryan, E.M. Laziev, K. Manukyan, I.N. Margaryan, V. Sahakyan, A. Sargsyan, A. Tarloyan, A.V. Tsakanian, V.M. Tsakanov, A. Vardanyan CANDLE, Yerevan, Armenia T. Vardanyan YSU, Yerevan, Armenia
	The low energy sub-picosecond duration electron bunches with extremely small beam emittance have wide applications in advanced research of new accelerator concepts, radiation physics, time-resolved pulse radiolysis and electron diffraction. The conceptual design and experimental program of the Advanced Research Electron Accelerator Laboratory (AREAL) at CANDLE based on photocathode RF gun are presented. The AREAL design implies single and multibunch operation modes with variable beam energy of 5-20 MeV and 10-100 pC bunch charge. The design is based on 3 GHz 1.6 cells RF gun followed by S-Band accelerating linac.

TUPC043	SEM Field Emission Probe Surface Science Study	cathode, vacuum, electron, gun	1096
	L. Laurent, R.E. Kirby, S.G. Tantawi SLAC, Menlo Park, California, USA
	Funding: This work is supported by Department of Energy Contract No. DE-AC03- 76SF00515. After decades of rf breakdown research, a common acknowledgement among researchers is that a better understanding of what is happening on the surface at a microscopic level needs to be the impetus for future studies. We are designing and fabricating an electron microscope-based high-electric-field current-emission probe to study topographic material features which will enable us to better understand and further advance the technology of high-brightness photocathode rf guns and enable the study of high gradient phenomena. The SEM field emission probe will provide an important diagnostic tool allowing cathodes and high gradient surfaces to be evaluated before and after testing and will help identify and understand the relationship between high field emission locations and vacuum breakdown, non-uniform emission, surface cracking, hotspots, etc. The preliminary results and 2012 goals will be presented.

TUPC057	Femtosecond Photoinjector and Relativistic Electron Microscopy	gun, electron, emittance, cathode	1126
	J. Yang, K. Kan, Y. Murooka, N. Naruse, K. Tanimura, Y. Yoshida ISIR, Osaka, Japan J. Urakawa KEK, Ibaraki, Japan
	A new rf gun driven by a femtosecond laser has been developed successfully for the relativistic electron diffraction in Osaka University for the study of ultrafast dynamics of intricate molecular and atomic processes in materials. The beam dynamics of femtosecond electron bunch in the rf gun were investigated to achieve a low-emittance and low-energy-spread; i.e. 0.1 mm-mrad and 10^-4. A time-resolved relativistic electron microscopy is being developed to reveal the hidden dynamics on the femtosecond and nanometer scales. The same demonstrations of the MeV electron diffraction/imaging measurements were reported.

TUPC058	Design of a Chirping Cell Attached RF Gun for Ultrashort Electron Generation	gun, electron, cavity, radiation	1129
	K. Sakaue, K. Tamai, M. Washio RISE, Tokyo, Japan J. Urakawa KEK, Ibaraki, Japan
	Funding: Work supported by JSPS Grant-in-Aid for Scientific Research (A) 10001690 We have been developing an S-band photocathode rf electron gun at Waseda university. Our rf-gun cavity was firstly designed by BNL and then, modified by our group. In this paper, we will introduce a newly designed rf-gun cavity with energy chirping cell. To generate an energy chirped electron bunch, we attached extra-cell for 1.6cell rf-gun cavity. Cavity design was done by Superfish and particle tracing by PARMELA. By optimizing the chirping cell, we observed linear chirped electron bunch. The front electron have lower energy than rear. Then transporting about 2m, the bunch can be compressed down to 200fsec electron bunch with the charge of 160pC. This ultrashort bunch will be able to use for generating CSR THz radiation, pumping some material to be studied by pulse radiolysis method, and so on. In this conference, the design of chirping cell attached rf-gun, the results of tracing simulation and plan of manufacturing will be presented.

TUPC059	Study on Energy Compensation by RF Amplitude Modulation for High Intense Electron Beam Generated by a Photocathode RF-Gun	beam-loading, electron, cavity, gun	1132
	Y. Yokoyama, T. Aoki, K. Sakaue, T. Suzuki, M. Washio, T. Yamamoto RISE, Tokyo, Japan H. Hayano, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan S. Kashiwagi Tohoku University, Research Center for Electron Photon Science, Sendai, Japan R. Kuroda AIST, Tsukuba, Ibaraki, Japan
	Funding: Work supported by JSPS Grant-in-Aid for Scientific Research(A)10001690 and JST Quantum Beam Program. At Waseda University, we have been studying a high quality electron beam generation and its application experiments with a Cs-Te photocathode RF-Gun. To generate more intense and stable electron beam, we have been developing the cathode irradiating UV laser which consists of optical fiber amplifier and LD pumped amplifier. As the result, more than 100 multi-bunch electron beam with 1nC each bunch charge was obtained. However, it is considered that the accelerating voltage will decrease because of the beam loading effect. So we have studied the RF amplitude modulation technique to compensate the beam energy difference. The energy difference will caused by transient accelerating voltage in RF-Gun cavity and beam loading effect. As the result of this compensation method, the energy difference has been compensated to 1%p-p, while 5%p-p without compensation. In this conference, we will report the details of energy compensation method using the RF amplitude modulation, the results of beam experiments and the future plans.

TUPC065	Upgrade of the ISAC Time-of-flight System	ion, ISAC, alignment, diagnostics	1147
	V.A. Verzilov, J. Lassen, R.E. Laxdal, M. Marchetto TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
	The ISAC facility at TRIUMF produces stable and radioactive ion beams in a wide range of intensities and energies. The beam diagnostics was designed to support the beam delivery in every possible operating regime. Thus, the time-of-flight system is capable of measuring the beam velocity with accuracy of better than 0.1% at beam intensities from 10¹1 down to ~ 10⁴ ions per second. It consists of three high resolution timing secondary electron emission monitors and has been in operation since 2006. Recently all three monitors were rebuilt with the aim to facilitate monitor alignment with respect to the beam. The system was also equipped with an UV laser that allows perform an accurate absolute calibration and monitor tuning with no beam present.

TUPC066	Charged Particle Beam Profile Detector based on Yb-doped Optical Fibers	radiation, proton, ion, linac	1150
	C.S. Søndergaard Aarhus University Hospital, Aarhus, Denmark A. Baurichter, B.R. Nielsen Danfysik A/S, Jyllinge, Denmark G. Boudreault Rigshospitalet Copenhagen, PET and Cyclotron Unit, Copenhagen, Denmark K. Hansen, D.V. Madsen, J. Rasmussen, B.F. Skipper Aarhus School of Engineering, Aarhus, Denmark M. Kristensen Aarhus University, Aarhus, Denmark S.P. Møller ISA, Aarhus, Denmark A. Peters HIT, Heidelberg, Germany
	Funding: The Danish National Advanced Technology Foundation, contract # 002-2005-1 A radiation robust, high dynamic range beam profile detector based on scintillating fibers will be presented. The beam profile detector has been developed for particle therapy type ion beams of multiple hundreds MeV/n in the intensity range from 10⁵ to 10⁹ ions/s as a simple and less expensive replacement for MWPC based detectors. Scintillating fibers are typically based on doped polymers, which are sensitive to radiation damage. Here we report on the advantage of using silica optical fibers doped with rare-earth elements for the purpose of detecting ionizing radiation. Specifically, we find that ytterbium doped fibers generate a strong emission signal in the near-infrared from the Yb³⁺ state when penetrated by ionizing radiation, and that the emission has a high resistance against the accumulated dose in the fiber. We demonstrate the use of such fibers in a beam profile detector for charged particle beams in medical applications (radionuclide production and hadron therapy); more generally they are a promising alternative for prolonged used in ionizing radiation, such as accelerator diagnostics equipment or space applications.

TUPC074	A New Counting Silicon Strip Detector System for Precise Compton Polarimetry	electron, polarization, photon, scattering	1171
	R. Zimmermann, W. Hillert, J.C. Wittschen ELSA, Bonn, Germany
	Funding: Supported by the German Research Foundation within the SFB/TR16 A Compton polarimeter is currently being installed at the Electron Stretcher Facility ELSA to monitor the degree of polarization of the stored electron beam. For this purpose, circularly polarized light that is emitted by a laser and backscattered off the beam has to be detected. Above all, as a result of ELSA's beam energies, it is necessary to measure the shift of the center of the photon spatial distribution which is obtained when the polarization of the laser is switched from left-hand to right-hand circular polarization with an accuracy of a few microns. In order to meet the required specifications, a new counting silicon strip detector system has been developed in cooperation with the SiLab/ATLAS group of the Physics Institute of the University of Bonn. In this contribution, the design of the system will be presented and first results will be shown.

TUPC076	Realization of a High Bandwidth Bunch Arrival-time Monitor with Cone-shaped Pickup Electrodes for FLASH and XFEL	pick-up, electron, coupling, free-electron-laser	1177
	A. Angelovski, M. Hansli, R. Jakoby, A. Kuhl, A. Penirschke, S. Schnepp TU Darmstadt, Darmstadt, Germany M. Bousonville, H. Schlarb DESY, Hamburg, Germany T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Funded by the Federal Ministry of Education and Research (BMBF): 05K10RDA In the Free Electron Laser in Hamburg (FLASH) an electro-optical system is used as a Bunch Arrival time Monitor (BAM). The time-of-arrival resolution is proportional to the steepness of the beam pick-up signal at the first zero-crossing. Future experiments will be conducted using significantly lower bunch charges resulting in a reduced signal steepness. This requires BAM pickup electrodes with increased bandwidth as introduced in . This paper presents the implementation and measurement results of a high bandwidth cone-shaped pickup capable of operating in the frequency range up to 40 GHz. The slope steepness at the zero crossing is investigated for a simplified equivalent circuit model. RF-measurements have been performed using a non-hermetic prototype of the BAM pickups for assessing the influence of manufacturing tolerances on the sensor performance. The measurements are compared to simulation results obtained by CST PARTICLE STUDIO®. F. Loehl et al., Proc. of DIPAC2007, WEPB15, p. 262 (2007). ** A. Angelovski et al., "Pickup design for a high resolution Bunch Arrival time Monitor for FLASH and XFEL", DIPAC2011.

TUPC079	Sensitivity and Tolerance Analysis of a New Bunch Arrival-time Monitor Pickup Design for FLASH and XFEL	pick-up, simulation, electron, free-electron-laser	1186
	A. Kuhl, A. Angelovski, R. Jakoby, A. Penirschke, S. Schnepp TU Darmstadt, Darmstadt, Germany M. Bousonville, H. Schlarb DESY, Hamburg, Germany T. Weiland TEMF, TU Darmstadt, Darmstadt, Germany
	Funding: Supported by the Graduate School of Computational Engineering at TU Darmstadt and the Federal Ministry of Education and Research (BMBF): 05K10RDA "Weiterentwickung eines Ankunftszeitmonitors" The Free Electron Laser in Hamburg (FLASH) is equipped with Bunch Arrival Time Monitors (BAM), which provide for a time resolution of less than 10 fs for bunch charges higher than 0.2 nC. Future experiments, however, will aim at generating FEL light pulses from a broad range of bunch charges down to 10 pC. In these circumstances the requirements on the time resolution will no longer be fulfilled, which demands for a larger bandwidth of the pickup system. A new cone-shaped pickup, which has a bandwidth greater than 40 GHz has been proposed. At high frequencies, small manufacturing tolerances might have great influence on the pickup signal. A sensitivity analysis of several manufacturing tolerances in the pickup design regarding their influence on the output signal was carried out (by means of CST PARTICLE STUDIO®). These results are utilized for setting limits to the manufacturing tolerances. M.K. Bock et al., IPAC2010, WEOCMH02, Kyoto, Japan, 2010. ** A. Kuhl et al., "Design eines hochauflösenden Ankunftszeitmonitor für FLASH", DPG Frühjahrstagung 2011, Karlsruhe, Germany.

TUPC081	Diagnostics of Femtosecond Low-charge Electron Bunches at REGAE	electron, photon, diagnostics, simulation	1192
	S. Bayesteh Uni HH, Hamburg, Germany H. Delsim-Hashemi DESY, Hamburg, Germany
	A new linac is constructed at DESY as the electron source fo "Relativistic Electron Gun for Atomic Exploration (REGAE)". REGAE is mainly established for a Femtosecond electron diffraction experiment presenting structural information on atomic transition states occurring in the sub-hundred femtosecond time-scale. REGAE comprises a photo-cathode gun followed by normal conducting 1.5 cell RF cavity to provide sub pico-Coulomb charge of 2 to 5 MeV energy with a coherent length in the range of 30nm. In order to produce and maintain such high quality electron bunches, sophisticated single-shot diagnostics is mandatory to monitor the properties. Diagnostics include emittance, energy, energy spread and bunch length measurement. In this paper the conceptual ideas and steps toward realization of these diagnostics are presented with a detailed focus on transverse diagnostics. As for photon source of transversal diagnostics, scintillators are studied. Simulation results show which material suits the best for REGAE parameters. Layout of a home-made intensified camera is presented. The method discussed in this paper would also be advantageous for low-charge Free Electron Lasers.

TUPC086	A Setup for Single Shot Electro Optical Bunch Length Measurements at the ANKA Storage Ring	electron, storage-ring, synchrotron, radiation	1206
	N. Hiller, E. Huttel, A.-S. Müller, A. Plech KIT, Karlsruhe, Germany F. Müller, P. Peier, V. Schlott PSI, Villigen, Switzerland
	Funding: Supported by the Initiative and Networking Fund of the Helmholtz Association under VH-NG-320. Sponsored by the German Federal Ministry of Education and Research under contract number 05K10VKC Single shot electro optical bunch length measurements, in particular using spectral decoding, are foreseen for the ANKA storage ring. This will allow to resolve fast changes of bunch deformation and structure during the low alpha operation (2-15 ps rms bunch length). This technique uses a chirped laser pulse to probe the field induced birefringence in an electro optical crystal. The laser pulse is then analyzed in a single shot spectrometer. To obtain the birefringence modulation one can either use the near field of the electron bunch (placing the crystal close to the electron bunch in the UHV system of the storage ring), or the far field (coherent synchrotron radiation in the THz range at a THz-/IR-Beamline). The laser needs to supply: sufficient tunability of pulse length, a wide spectrum to allow for a sub-ps resolution. Additionally it must provide a mode-locked operation synchronized to the bunch revolution clock. For this purpose, a mode locked Ytterbium fibre laser system which operates at 10³⁰ nm has been developed at the Paul-Scherrer Institute in Switzerland. We give an overview over the experimental set up in the ANKA storage ring and the status of the project.

TUPC091	Operational Results of the Diamond-based Halo Monitor during Commissioning of SPring-8 XFEL (SACLA)	electron, undulator, wakefield, scattering	1218
	H. Aoyagi JASRI/SPring-8, Hyogo-ken, Japan Y. Asano, H. Kitamura, T. Tanaka RIKEN/SPring-8, Hyogo, Japan
	Funding: This work is partly supported by Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (c) 21604017. Measurement of electron beam halo is very important issue for X-ray free electron laser and synchrotron radiation facilities, because the beam halo may cause radiation damage of undulator magnets. Furthermore, it may cause degradation in quality of electron beam, and radio activation of beam ducts and components. In order to prevent these situations, a diamond-based halo monitor (HM) has been developed for the SPring-8 Angstrom Compact free electron LAser (SACLA). We have achieved excellent detection limit of 0.3 fC/pulse for single-shot measurement, which corresponds to the ratio of 10^-6 to the beam core. The commissioning of the HM, which was installed at the upstream of 90m undulator, has been carried out, and it has been figured out that the intensity of the beam halo can be measured very nicely since secondary electrons and bremsstrahlung that are emitted in the accelerator components have not been observed. We also describe systematic profile measurements of the beam halo and operational results of the HM during the commissioning of SACLA.

TUPC092	Transverse C-band Deflecting Structure for Longitudinal Phase Space Diagnostics in the XFEL/SPring-8 “SACLA”	vacuum, coupling, diagnostics, emittance	1221
	H. Ego RIKEN/SPring-8, Hyogo, Japan T. Hashirano, S. Miura MHI, Hiroshima, Japan H. Maesaka, Y. Otake RIKEN Spring-8 Harima, Hyogo, Japan T. Sakurai RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
	In SPring-8, the 8 GeV compact XFEL “SACLA” is under commissioning. A single bunch of electrons is compressed down to about 30 fs for brilliant SASE X-ray lasing. It is an important key of stable lasing to investigate the longitudinal phase space and the sliced emittance of a lasing part of the bunch by using a transverse RF deflector. We developed a high gradient C-band deflecting structure operated at 5712 MHz for the bunch diagnosis with a resolution of femtosecond regime at a limited space in the SACLA. The backward travelling-wave of the HEM11-5pi/6 mode is excited in the cylindrical structure periodically loaded with racetrack-shaped irises. The featuring irises suppress rotation of the deflection plane and generate strong cell-to-cell coupling for stable resonance. Two 1.8m-long structures were fabricated and installed in the SACLA. They successfully generated a deflection voltage over 40 MV and pitched the bunch at the zero-crossing RF phase. In this paper, we present the details of the fabrication and the deflecting performance of the structures applied to the diagnosis.

TUPC110	Ultrashort Bunch Train Longitudinal Diagnostics using RF Deflecting Structure	cavity, diagnostics, betatron, emittance	1275
	Y. Yang, H. Chen, Y.-C. Du, W.-H. Huang, C. Li, L.X. Yan TUB, Beijing, People's Republic of China
	Ultrashort electron bunch train has been produced using UV laser stacking in Tsinghua University. With an S-band deflecting cavity inserted into the Tsinghua Thomson Scattering beamline, it is possible to characterize the bunch train longitudinal property. This paper briefly introduced the measurement layout in our lab and reported the recent experiment results, including bunch train profile measurement and longitudinal phase space. The main sources of error are also discussed.

TUPC124	Laser Wire Emittance Measurement Line at CLIC*	emittance, photon, collider, electron	1308
	H. Garcia, Yu.A. Kubyshin UPC, Barcelona, Spain T. Aumeyr, G.A. Blair JAI, Egham, Surrey, United Kingdom D. Schulte, F. Stulle CERN, Geneva, Switzerland
	A precise measurement of the transverse beam size and beam emittances upstream of the final focus is essential for ensuring the full luminosity at future linear colliders. A scheme for the emittance measurements at the RTML line of the CLIC using laser-wire beam profile monitors is described. A lattice of the measurement line is discussed and results of simulations of statistical and machine-related errors and of their impact on the accuracy of the emittance reconstruction are given. Modes of operation of the laser wire system and its main characteristics are discussed.

TUPC133	Instrumentation for the 12 GHz Stand-alone Test-stand to Test CLIC Acceleration Structures	electron, vacuum, diagnostics, ion	1335
	M. Jacewicz, R.J.M.Y. Ruber, V.G. Ziemann Uppsala University, Uppsala, Sweden J.W. Kovermann CERN, Geneva, Switzerland
	Vacuum breakdown is one of the primary limitations in the design and construction of high energy accelerators operating with warm accelerating structures (ACS) such as CLIC linear collider because the mechanisms that cause the breakdown are still a mystery. The ongoing experimental work is trying to benchmark the theoretical models focusing on the physics of vacuum breakdown which is responsible for the observed discharges. The CLIC collaboration is preparing a dedicated 12 GHz test-stand to observe the characteristics of the RF discharges and their eroding effects on the ACS. The instrumentation for the test-stand must be versatile and allow for the conditioning of the ACS with measurements of the breakdown rates at different power levels as well as detection of the dark current and light emission directly relevant to breakdown physics. For that purpose we are developing 2 novel instruments. A pepper-pot chamber with an external magnetic spectrometer for measurement of the spatial and energy distributions of the electrons emitted from the ACS and an optical laser system for probing the ACS to observe the effect of a discharge on the transmitted light.

TUPC139	Overview of the CLIC Beam Instrumentation	linac, cavity, beam-losses, instrumentation	1350
	T. Lefèvre CERN, Geneva, Switzerland
	Driven by beam dynamic considerations the Compact Linear Collider (CLIC) is expected to require extremely tight tolerances on most beam parameters. An important milestone was reached in 2011 with the completion of the CLIC conceptual design report. In this context the requirements for CLIC beam instrumentation has been reviewed and studied in detail for the whole accelerator complex with the aim of demonstrating feasibility. A preliminary choice has been made for every CLIC instrument, serving as a baseline scenario for the next phase of the project which will concentrate on the detailed design, engineering and test of CLIC devices. Whenever possible existing solutions have been studied, focusing on any improvements necessary to meet the CLIC performance criteria. When no such devices exists, or if cost considerations come into play, new technologies have been under study. Several prototypes are already well advanced and are currently under test. This paper presents an overview of CLIC beam instrumentation, the possible reach of their performance and an outlook on future developments.

TUPC142	The Particle Identification System for the MICE Beamline Characterization	emittance, beam-losses, electron, solenoid	1356
	M. Bonesini INFN MIB, MILANO, Italy Y. Karadzhov DPNC, Genève, Switzerland
	The International Muon Ionization Cooling Experiment (MICE) will carry out a systematic investigation of a ionization cooling section of a muon beam, for the future Neutrino Factory and the future Muon Collider. As the emittance measurement will be done on a particle-by-particle basis, a sophisticated beam instrumentation is needed to measure both particle coordinates and timing vs RF in a harsh environment due to high particle rates, fringe magnetic fields and RF backgrounds. A PID system, based on three time-of-flight stations (with resolutions up to 50-60 ps), two Aerogel Cerenkov counters and a KLOE-like calorimeter (KL) has been constructed and has allowed the commissioning of the MICE muon beamline in 2010. It will be complemented in 2011 by an Electron Muon Ranger to determine the muon range at the downstream end of the cooling section. Detector performances, as obtained in the 2010 run, will be shown and the use of PD detectors for the beamline characterization, including a preliminary measure of emittance, fully illustrated.

TUPC151	Cherenkov Fibre Optic Beam Loss Monitor at ALICE	beam-losses, photon, electron, monitoring	1383
	A. Intermite The University of Liverpool, Liverpool, United Kingdom A. Intermite, M. Putignano, A. Wolski Cockcroft Institute, Warrington, Cheshire, United Kingdom
	The need for real-time monitoring of beam losses, including evaluation of their intensity and the localization of their exact position, together with the possibility to overcome the limitations due to the reduced space for the diagnostics, makes optical fibres (using the Cherenkov Effect) one of the most suitable and explored candidate for beam loss monitoring. In this contribution, we report on an optical fibre beam loss monitor based on large numerical aperture pure silicon fibres and silicon photomultipliers, tested at ALICE, Daresbury Laboratories, UK. The original design of the sensor has the advantage to combine the functions of a real time detector and a transmission line. It also allows reading the signals independently and determining the time and position of the losses without the use of an external trigger.

TUPC158	Micron-scale Laser-wire at the ATF-II at KEK Commissioning and Results	electron, optics, photon, diagnostics	1401
	L.J. Nevay, G.A. Blair, S.T. Boogert, L. Corner, L.C. Deacon, V. Karataev, R. Walczak JAI, Oxford, United Kingdom A.S. Aryshev, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	We present the first results from the commissioning of the upgraded laser-wire experiment at the Accelerator Test Facility 2 (ATF2) at KEK. A new laser transport line and beam diagnostics were used to collide 150 mJ, 167 ps long laser pulses with 1.28 GeV, 30 ps long electron bunches to measure the vertical transverse size. Additionally, a new detector was installed with a reduced area for lower background. Initial scans showing a convoluted beam size of 19.2 ± 0.2 microns were used to tune the electron beam optics and reduce this down to 8.1 ± 0.1 microns. Laser pulse energy and charge dependency were investigated showing a linear relationship in both with a minimum laser energy of 20 mJ required for observable signal with this laser and setup.

TUPC169	Single-shot Electro-optic Sampling of Coherent Transition Radiation at the A0 Photoinjector	polarization, radiation, diagnostics, electron	1431
	T.J. Maxwell, P. Piot Northern Illinois University, DeKalb, Illinois, USA J. Ruan, R.M. Thurman-Keup Fermilab, Batavia, USA
	Funding: Work supported by Fermi Research Alliance, LLC under U.S. Dept. of Energy Contract No. DE-AC02-07CH11359, and Northern Illinois Univ. under US Dept. of Defense DURIP program Contract N00014-08-1-10⁶⁴. Future collider applications and present high-gradient laser plasma wakefield accelerators operating with picosecond bunch durations place a higher demand on the time resolution of bunch distribution diagnostics. This demand has led to significant advancements in the field of electro-optic sampling over the past ten years. These methods allow the probing of diagnostic light such as coherent transition radiation () or the bunch wakefields () with sub-picosecond time resolution. Potential applications in shot-to-shot, non-interceptive diagnostics continue to be pursued for live beam monitoring of collider and pump-probe experiments. Related to our developing work with electro-optic imaging, we present results on single-shot electro-optic sampling of the coherent transition radiation from bunches generated at the A0 photoinjector. J. van Tilborg et al., Phys. Rev. Lett. 96, 014801 (2006). ** M. J. Fitch et al., Phys. Rev. Lett. 87 034801 (2001).

TUPC171	2D Optical Streaking for Ultra-short Electron Beam Diagnostics	electron, simulation, diagnostics, linac	1437
	L. Wang, Y.T. Ding, Z. Huang SLAC, Menlo Park, California, USA
	We propose a novel approach to measure the short electron bunch profile at micrometer level. Low energy electrons generated during beam-gas ionization are simultaneously modulated by the transverse electric field of a circularly-polarized laser, and then they are collected at a down-stream screen where the angular modulation are converted to a circular shape there. The longitudinal bunch profile is simply represented by the angular distribution of the electrons on the screen. We only need to know the laser wavelength for calibration and there is no phase synchronization problem. Meanwhile the required laser power is also relatively low in this setup. Some simulations examples and resolution of this method will be discussed.

TUPC178	Charge Lifetime Study of K2CsSb Photocathode Inside a Jlab DC High Voltage Gun	cathode, vacuum, gun, high-voltage	1443
	R.R. Mammei, M. Poelker, R. Suleiman JLAB, Newport News, Virginia, USA J.L. McCarter UVa, Charlottesville, Virginia, USA T. Rao, J. Smedley BNL, Upton, Long Island, New York, USA
	Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE Two photocathodes are frequently considered for generating high average current electron beams and/or beams with high brightness for current and future accelerator applications: GaAs:Cs and K2CsSb. Each photocathode has advantages and disadvantages, and need to demonstrate performance at “production” accelerator facilities. To this end a K2CsSb photocathode was manufactured at Brookhaven National Lab and delivered to Jefferson Lab within a compact vacuum apparatus at pressure ~ 5x10^-11 Torr. This photocathode was installed inside a dc high voltage photogun biased at voltages up to 200 kV, and illuminated with laser light at 440 or 532 nm, to generate beams up to 20 mA. Photocathode charge lifetime measurements indicate that under some conditions this cathode has exceptionally high charge lifetime, without measurable QE decay, even from the center of the photocathode where operation using GaAs photocathodes is precluded due to ion bombardment. These studies also suggest a complex QE decay mechanism likely related to chemistry and localized heating via the laser beam.

TUPO002	High Flux Polarized Gamma Rays Production: First Measurements with a Four-mirror Cavity at the ATF	cavity, electron, positron, damping	1446
	N. Delerue, J. Bonis, I. Chaikovska, R. Chiche, R. Cizeron, M. Cohen, P. Cornebise, R. Flaminio, D. Jehanno, F. Labaye, M. Lacroix, Y. Peinaud, L. Pinard, V. Soskov, A. Variola, Z.F. Zomer LAL, Orsay, France T. Akagi, S. Miyoshi Hiroshima University, Graduate School of Advanced Sciences of Matter, Higashi-Hiroshima, Japan S. Araki, Y. Funahashi, Y. Honda, T. Omori, H. Shimizu, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan E. Cormier CELIA, Talence, France T. Takahashi Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan
	Funding: ANR, IN2P3 The next generation of e+/e^- colliders will require the production of a very intense flux of gamma rays to allow polarized positrons to be produced in sufficient quantities. To demonstrate that this can be achieved a four-mirror cavity has recently been installed at the Accelerator Test Facility (ATF) at KEK to produce a high flux of polarized gamma rays by inverse Compton scattering. A four-mirror non-planar geometry is used to ensure the polarization of the gamma rays produced. The main mechanical features of the cavity are presented. A fibre amplifier is used to inject about 10W in the high finesse cavity with a gain of 1000. A digital feedback system is used to keep the cavity at the length required for the optimal power enhancement. First preliminary measurements show that on some beam crossings the interactions produce more than 25 photons with an average energy of about 24 MeV. Several upgrades currently in progress are described.

TUPO004	Generation of Attosecond Soft X-ray Pulses in a Longitudinal Space Charge Amplifier	undulator, electron, space-charge, radiation	1449
	M. Dohlus, E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	A longitudinal space charge amplifier (LSCA), operating in soft x-ray regime, was recently proposed. Such an amplifier consists of a few amplification cascades (focusing channel and chicane) and a short radiator undulator in the end. Broadband nature of LSCA supports generation of few-cycle pulses as well as wavelength compression. In this paper we consider an application of these properties of LSCA for generation of attosecond x-ray pulses. It is shown that a compact and cheap addition to the soft x-ray free electron laser facility FLASH would allow to generate 60 attosecond (FWHM) long x-ray pulses with the peak power at 100 MW level and a contrast above 98%.

TUPO005	Design Optimization for a Non-Planar Undulator for the JETI-Laser Wakefield Accelerator in Jena	undulator, electron, radiation, wakefield	1452
	V. Afonso Rodriguez, T. Baumbach, A. Bernhard, G. Fuchert, A. Keilmann, P. Peiffer, C. Widmann KIT, Karlsruhe, Germany M. Kaluza, M. Nicolai IOQ, Jena, Germany R. Rossmanith Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
	In a laser wakefield accelerator (LWFA), excited by a femtosecond laser pulse electrons are accelerated to several 100 MeV within a few centimeters. The energy spread of the electron beam is relatively large and varies from shot to shot. In order to obtain monochromatic photons in an undulator despite the energy spread, the following idea was proposed. Two bending magnets and a drift space in between produces dispersion so that particles with different energies have different transverse positions. The beam enters a non-planar undulator, e.g. cylindrical pole geometry, where the K-value also varies with transverse position. If the two variations in the transverse direction (particle energy and K-value) compensate each other the generated light is more monochromatic than with a conventional planar undulator. In this paper such a modified undulator design optimized for the JETI-LWFA in Jena is presented. An experiment to test this concept is in preparation.

TUPO008	Electron Linac Optimization for Driving Bright Gamma-ray Sources based on Compton Back-scattering	electron, photon, linac, emittance	1461
	L. Serafini, F. Broggi, C. De Martinis, D. Giove Istituto Nazionale di Fisica Nucleare, Milano, Italy D. Alesini, P. Antici, A. Bacci, M. Bellaveglia, R. Boni, E. Chiadroni, G. Di Pirro, A. Esposito, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, E. Pace, A.R. Rossi, B. Spataro, P. Tomassini, C. Vaccarezza INFN/LNF, Frascati (Roma), Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy C. Maroli, V. Petrillo Universita' degli Studi di Milano, Milano, Italy M. Migliorati, A. Mostacci, L. Palumbo Rome University La Sapienza, Roma, Italy
	We study the optimal lay-out and RF frequency for a room temperature GeV-class Electron Linac aiming at producing electron beams that enhance gamma-ray sources based on Compton back-scattering. These emerging novel sources, generating tunable, mono-chromatic, bright photon beams in the range of 5-20 MeV for nuclear physics as well as nuclear engineering, rely on both, high quality electron beams and J-class high repetition-rate synchronized laser systems in order to achieve the maximum spectral density of the gamma-ray beam (# photons/sec/eV). The best option among the conventionally used RF linac-bands (S, C, X) and possible hybrid schemes will be analyzed and discussed, focusing the study in terms of best performances for the gamma-ray source, its reliability and compactness. We show that the best possible candidates for a Gamma-ray driver are quite similar to those of FEL Linacs.

TUPO012	Stable Planner Type Four-mirror Cavity Development for X-ray Production as Basic Development of Quantum Beam Technology Program	cavity, injection, superconducting-RF, target	1470
	H. Shimizu, Y. Higashi, Y. Honda, J. Urakawa KEK, Ibaraki, Japan
	As the development of quantum beam technology program, a facility to produce a semi-monochromatic X-ray via inverse Compton scattering with an electron beam accelerated by a superconducting RF cavity and a fiber amplified high power laser stacked in an external optical cavity system are now under construction. To achieve high brightness of Compton X-ray, we introduced a chicane with about a 1m-long zero dispersion straight section that includes IP. Head on collision scheme improves the yield of X-ray, but to do so, a huge and stout external optical cavity system must be needed. According to this demand, we develop a quite tolerable planner type four-mirror cavity with movable mirror mount system. In this paper, results obtained by the cavity construction and also laser development activities are described.

TUPO013	Development of Pulse Width Measurement Techniques in a Picosecond Range of Ultra-short Gamma Ray Pulses	photon, electron, storage-ring, scattering	1473
	Y. Taira, M. Hosaka, K. Soda, N. Yamamoto Nagoya University, Nagoya, Japan M. Adachi, M. Katoh, H. Zen Sokendai - Okazaki, Okazaki, Aichi, Japan T. Tanikawa UVSOR, Okazaki, Japan
	Funding: This work was supported by Grants-in-Aid for Scientific Research from Japan Society for the Promotion of Science (JSPS). We are developing the ultra-short gamma ray pulse source with the energy of MeV region based on laser Compton scattering at the 750 MeV electron storage ring, UVSOR-II. Gamma rays with pulse width of sub-picosecond range can be generated by injecting femtosecond laser pulses into the electron beam from the vertical 90-degree direction* because the electron beam circulating in the storage ring is focused more tightly in the vertical direction than in the longitudinal direction. The energy, intensity, and pulse width of the gamma rays can be tuned by changing the collision angle between the electron beam and the laser. We are developing pulse width measurement techniques of ultra-short gamma ray pulses at present. As the first step of the pulse width measurement, we used a fast response photodetector, Geiger-mode APD, the time resolution of which is few hundreds picoseconds. Although we cannot measure the pulse width of the gamma rays with sub-picosecond range using this detector, we could measure the pulse width of the gamma rays as 430 ps or less by measuring the timing of Cherenkov radiations generated from the gamma rays. * Y. Taira et al., Nucl. Instrum. Meth. A, in press, 2010.

TUPO014	High-flux Gamma-ray Generation by Laser Compton Scattering in the SAGA-LS Storage Ring	photon, storage-ring, survey, electron	1476
	T. Kaneyasu, Y. Iwasaki, S. Koda, Y. Takabayashi SAGA, Tosu, Japan
	We constructed an experimental setup for high-flux gamma-ray generation by laser Compton scattering (LCS) in the SAGA-LS storage ring. The SAGA-LS is a synchrotron radiation (SR) facility consisting of a 255 MeV injector linac and a 1.4 GeV storage ring. We employed a CO2 laser having a wavelength of 10.6 micrometer to produce gamma-rays in the few MeV region in conjunction with the SR user time. The LCS gamma-ray up to the maximum energy of 3.5 MeV is generated via head-on collision between the laser photons and the 1.4 GeV stored beam. Since the energy acceptance of the storage ring is well above the maximum gamma-ray energy, the LCS experiment can be performed without reducing the beam lifetime. As a first step for high-flux gamma-ray generation, we use a small 10 W CO2 laser for beam test. The LCS event rate is designed to be 2·10⁸ ph/s with a beam current of 300 mA and a laser power of 10 W. A further increase of the LCS event rate in the order of 10¹0 ph/s is expected when a kW class laser is utilized. We report on the characteristics of the LCS gamma-rays observed in the low current beam test and an experimental result for evaluating the gamma-ray flux at a current of 300 mA.

TUPO023	Narrow Spectral Bandwidth Optimization of Compton Scattering Sources	electron, scattering, simulation, emittance	1488
	F. Albert, S.G. Anderson, S.M. Betts, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, T.L. Houck, R.A. Marsh, M. J. Messerly, C. Siders, S.S.Q. Wu LLNL, Livermore, California, USA
	We will be presenting the theoretical and numerical design and optimization of Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering sources. A new precision source with up to 2.5 MeV photon energies, enabled by state of the art laser and x-band linac technologies, is currently being built at LLNL. Various aspects of the theoretical design, including dose and brightness optimization, will be presented. We will review the potential sources of spectral broadening, in particular due to the electron beam properties. While it is also known that nonlinear effects occur in such light sources when the laser normalized potential is close to unity, we show that these can appear at lower values of the potential. A three dimensional analytical model and numerical benchmarks have been developed to model the source characteristics based on given laser and electron beam distributions, including nonlinear spectra. Since MEGa-ray sources are being developed for precision applications such as nuclear resonance fluorescence, assessing spectral broadening mechanisms is essential. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

TUPO024	Precision X-band Linac Technologies for Nuclear Photonics Gamma-ray Sources	gun, electron, photon, scattering	1491
	F.V. Hartemann, F. Albert, S.G. Anderson, C.P.J. Barty, A.J. Bayramian, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, T.L. Houck, R.A. Marsh, M. J. Messerly, S.S.Q. Wu LLNL, Livermore, California, USA C. Adolphsen, A.E. Candel, T.S. Chu, M.V. Fazio, E.N. Jongewaard, Z. Li, C. Limborg-Deprey, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou SLAC, Menlo Park, California, USA D. Cutoiu Horia Hulubei National Institute for Physics and Nuclear Engineering, Bucharest, Romania D. Ighigeanu, M. Toma INFLPR, Bucharest - Magurele, Romania V.A. Semenov UCB, Berkeley, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. Nuclear photonics is an emerging field of research requiring new tools, including high spectral brightness, tunable gamma-ray sources; high photon energy, ultrahigh-resolution crystal spectrometers; and novel detectors. This presentation focuses on the precision linac technology required for Compton scattering gamma-ray light sources, and on the optimization of the laser and electron beam pulse format to achieve unprecedented spectral brightness. Within this context, high-gradient X-band technology will be shown to offer optimal performance in a compact package, when used in conjunction with the appropriate pulse format, and photocathode illumination and interaction laser technologies.

TUPS012	The Present Status of Vacuum System of XFEL in SPring-8	vacuum, shielding, electron, undulator	1542
	T. Bizen RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan T. Hasegawa RIKEN/SPring-8, Hyogo, Japan
	The vacuum component assembly and installation were completed by February in 2011. The total length of the vacuum system is about 630 m. A 455 sputter ion pumps and a 10⁸ NEG cartridge pumps generate vacuum. The average pressures are on the order of ·10^-7 Pa or less. The flange developed for C-band waveguide shows high reliability of vacuum seal.

TUPS031	The Installation of One 14 Meter Cell of TPS Vacuum System	vacuum, photon, synchrotron, site	1599
	H.P. Hsueh, C.K. Chan, C.H. Chang, C.-C. Chang, C.L. Chen, C.M. Cheng, Y.T. Cheng, G.-Y. Hsiung, S-N. Hsu, I.T. Huang, T.Y. Lee, H.Y. Yan, Y.C. Yang, C.S. huang NSRRC, Hsinchu, Taiwan J.-R. Chen National Tsing Hua University, Hsinchu, Taiwan
	The construction of a new 3 GeV synchrotron facility, Taiwan Photon Source, is ongoing. The vacuum system has been designed with off-site baking for arc section from sector gate valve to sector gate valve. There is no flange used in this arc section besides the two ends connected to sector gate valves. It is a tedious works for install such long vacuum system with aluminum chambers. In this poster, all the detailed installation procedures will be described. All the precaution inspection procedures for all vacuum components to prevent failed components to be installed will also be described. Every three weeks, one cell will be assembled and stored. Experience is being learned and could be used for the vacuum system of future new accelerator like FEL and others.

TUPS056	Synchronizing GEANT and 3D CAD - A Collaborative Engineering Study at ILD	simulation, free-electron-laser, electron	1659
	L. Hagge, S. Eucker, B. List, S. Sühl, N. Welle DESY, Hamburg, Germany
	The design of a detector for a high-energy physics experiment is a complex task, driven by two different communities: The scientists aim to optimize the detector performance, while engineers are tasked to provide a design that can actually be built. Both groups have their own specific tools (e.g. GEANT versus 3D CAD systems) that are employed to model the detector and improve its design. The ensuing models need to be compared and synchronized at regular intervals, so that optimizations made to the physics simulation model are propagated to the engineering world, and engineering solutions are reflected properly in the physics simulation. Based on experience from the European XFEL project, DESY is providing tools and processes for establishing this synchronization at a very early stage in the design of the International Large Detector (ILD) for the International Linear Collider (ILC). They have been used to analyze compliance and differences of the ILD engineering design and physics simulation models. The poster introduces tools and process and presents first results and lessons learned.

WEOAA01	The ThomX Project	injection, feedback, cavity, synchrotron	1903
	A. Variola LAL, Orsay, France
	Funding: Work supported by the EQUIPEX program, the Ile de France region, CNRS-IN2P3 and Université Paris Sud XI ThomX is a Compton source project in the range of the hard X rays (40 / 90 keV). The machine is composed of an injector Linac and a storage ring where an electron bunch collides with a laser pulse accumulated in a Fabry-Perot resonator. The final goal is to provide an X-rays average flux of 1011/10¹³ ph/s. The emitted flux will be characterized by a dedicated X-ray line. Different users are partners in the ThomX project, especially in the area of medical science and cultural heritage. Their main goal will be the transfer of all the experimental techniques developed on big synchrotron rings to these more compact and flexible machines. The project ThomX has recently been funded and will be located on the Orsay University campus. In this article the project and its associated scientific interest are presented.
	Slides WEOAA01 [5.947 MB]

WEXB01	Advanced Acceleration Schemes	electron, plasma, acceleration, wakefield	1945
	P.A. Naik, P.D. Gupta, B.S. Rao RRCAT, Indore (M.P.), India
	Review the progress and prospects of advanced acceleration concepts, including plasma acceleration, laser acceleration, and dielectric accelerators. Report ongoing and near-future experiments, and longer-term prospects for applications (e.g. compact X-ray sources, linear colliders, hadrontherapy).
	Slides WEXB01 [8.636 MB]

WEOAB01	Highly Polarized and High Quantum Efficiency Electron Source Using Transmission-type Photocathode	electron, gun, brightness, polarization	1950
	N. Yamamoto, F. Ichihashi, A. Mano, T. Nakanishi, Y. Takeda, T. Ujihara Nagoya University, Nagoya, Japan X.G. Jin Institute for Advanced Research, Nagoya, Japan
	The GaAs-type semiconductor photocathodes (PCs) with a negative electron affinity surface have been used as a polarized electron source and are expected as electron sources for next generation accelerators, such as Linear Colliders and Energy Recovery Linacs. Recently, we have developed transmission-type photocathodes (T-PCs).　By using T-PCs, polarized electron beam is extracted from the back-side of laser irradiation-side.　This scheme offers great merits in designing electron guns, such as short focusing of the laser light for a high brilliance electron beam and a simple geometrical structure avoiding an interference problem between the laser and the electron beam. The layer structure of the MOVPE-grown superlattice photocathode and the performance of 90% polarization, a super high brilliance, and a high quantum efficiency will be reported.
	Slides WEOAB01 [6.007 MB]

WEOAB03	The Production of High Quality Electron Beams in the ALPHA-X Laser Wakefield Accelerator	electron, plasma, emittance, radiation	1956
	S.M. Wiggins, M.P. Anania, C. Aniculaesei, E. Brunetti, S. Cipiccia, B. Ersfeld, M.R. Islam, R.C. Issac, D.A. Jaroszynski, G.G. Manahan, R.P. Shanks, G.H. Welsh USTRAT/SUPA, Glasgow, United Kingdom W.A. Gillespie University of Dundee, Nethergate, Dundee, Scotland, United Kingdom A. MacLeod UAD, Dundee, United Kingdom
	Funding: The U.K. EPSRC, the EC's Seventh Framework Programme (LASERLAB-EUROPE / LAPTECH, grant agreement no. 228334) and the Extreme Light Infrastructure (ELI) project. The Advanced Laser-Plasma High-Energy Accelerators towards X-rays (ALPHA-X) programme is developing laser-plasma accelerators for the production of ultra-short electron beams as drivers of incoherent and coherent radiation sources from plasma and magnetic undulators. Here we report on the latest laser wakefield accelerator experiments on the University of Strathclyde ALPHA-X accelerator beam line looking at high quality electron beams. ALPHA-X uses a 26 TW Ti:sapphire laser (energy 900 mJ, duration 35 fs) focused into a helium gas jet (nozzle length 2 mm) to generate high quality monoenergetic electron beams with central energy in the range 80-180 MeV. The beam is fully characterized in terms of the charge, bunch length, energy spread and transverse emittance. The energy spectrum (with less than 1% measured energy spread) is obtained using a high resolution magnetic dipole imaging spectrometer while pepper-pot mask measurements show that the normalized transverse emittance is as low as 1.1 pi mm mrad (resolution limited). The conditions needed to obtain this high quality are discussed.
	Slides WEOAB03 [2.904 MB]

WEYB01	Diagnostics for Ultra-low Emittance Beams	polarization, radiation, emittance, optics	1959
	J.W. Flanagan KEK, Ibaraki, Japan
	The achievement in recent years of beams with vertical emittance of a few pico-meters in a number of electron storage rings has presented challenges for diagnostics capable of beam size measurements in this regime. A number of different approaches have been developed for various machines (e.g. laser wire; interferometer; Shintake monitor; coded aperture; compound refractive lens). This presentation will review and compare the different methods, and discuss their strengths, weaknesses, ultimate limitations, and the situations where they might be appropriate; and consider possible future directions.
	Slides WEYB01 [2.553 MB]

WEOBB02	Bunch Length Diagnostic with Sub-femtosecond Resolution for High Brightness Electron Beams	undulator, electron, simulation, cavity	1967
	G. Andonian, E. Hemsing, P. Musumeci, J.B. Rosenzweig UCLA, Los Angeles, California, USA A.Y. Murokh RadiaBeam, Santa Monica, USA D. Xiang SLAC, Menlo Park, California, USA
	Next generation light sources require electron beams with high peak currents, typically achieved by compression techniques. The temporal diagnosis of these ultra-short beams demands enhanced resolution. We describe a scheme to achieve a temporal resolution on the order of sub-femtoseconds. The scheme is based on encoding the longitudinal profile of the beam on a transverse angular modulation, based on an interaction between the electron beam and a high-power laser in an undulator. This imposes a fast-sweep of the beam, on the order of sub-femtoseconds. A subsequent sweep in the orthogonal dimension by an rf deflecting cavity, imposes a "slow-sweep" on the order of sub-picoseconds. In this paper, we demonstrate applicability of this diagnostic scheme at the BNL ATF and specify the techniques required for practical applicability.
	Slides WEOBB02 [1.120 MB]

WEIB01	Chasing Femtoseconds – How Accelerators Can Benefit from Economies of Scale in Other Industries	optics, scattering, polarization, controls	1973
	M. Vidmar, J. Tratnik University of Ljubljana, Faculty of Electrical Engineering, Ljubljana, Slovenia P.L. Lemut COBIK, Solkan, Slovenia
	Building accelerators we frequently push the limits of what is possible in terms of performance. When trying to solve a very challenging engineering problem, we normally resort to specialization; we narrow our focus. This talk suggests a possible alternative path. Huge benefits and great results can be achieved by combining creative ideas and approaches with ideas and solutions borrowed from the economies of scale like telecommunications. The aim of the talk is to show possibilities for combining ideas, technologies and components from different industries into innovative products.
	Slides WEIB01 [0.799 MB]

WEPC051	Effect of Compton Scattering on the Electron Beam Dynamics at the ATF Damping Ring	electron, scattering, damping, cavity	2127
	I. Chaikovska, C. Bruni, N. Delerue, A. Variola, Z.F. Zomer LAL, Orsay, France K. Kubo, T. Naito, T. Omori, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	Compton scattering provides one of the most promising scheme to obtain polarized positrons for the next generation of e⁺e⁻ colliders. Moreover it is an attractive method to produce monochromatic high energy polarized gammas for nuclear applications and X-rays for compact light sources. In this framework a four-mirror Fabry-Perot cavity has been installed at the Accelerator Test Facility (ATF - KEK, Tsukuba, Japan) and will be used to produce an intense flux of polarized gamma rays by Compton scattering. For electrons at the energy of the ATF (1.28GeV) Compton scattering may result in a shorter lifetime due to the limited bucket acceptance. We have implemented the effect of Compton scattering on a 2D tracking code with a Monte-Carlo method. This code has been used to study the longitudinal dynamics of the electron beam at the ATF damping ring, in particular the evolution of the energy spread and the bunch length under Compton scattering. The results obtained are presented and discussed. Possible methods to observe the effect of Compton scattering on the ATF beam are proposed.

WEPC075	ITEP-TWAC Progress Report	ion, proton, injection, target	2193
	N.N. Alexeev, P.N. Alekseev, V. Andreev, A. Balabaev, V.I. Nikolaev, A.S. Ryabtsev, Yu.A. Satov, V.A. Schegolev, B.Y. Sharkov, A. Shumshurov, V.P. Zavodov ITEP, Moscow, Russia
	The program of the ITEP-TWAC Facility upgrade for next three years has been approved last year in the frame of National Research Center Kurchatov Institute taking up ITEP in accordance with government decision. It includes expanding of multimode using proton and heavy ion beams in different applications on a base of new accelerator technologies development. The laser ion source advantage of high temperature plasma generation has to be transformed to high current and high charge state ion beam of Z/A up to 0.4 for elements with A ~ 60 to be effectively stacked in the accumulator ring with multiple charge exchange injection technique. The new high current heavy ion RFQ section is in progress for the beam test. Accelerating system of accumulator ring U-10 is modified to increase compression voltage for stacked beam by factor of four. Design of proton injection and beam slow extraction for UK ring is performed for its utilizing as self-depending synchrotron in medical application and for imitation of cosmic radiation. The machine status analysis and current results of activities aiming at both subsequent improvement of beam parameters and expanding beam applications are presented.

WEPC143	First Operation of the SACLA Control System in SPring-8	controls, electron, monitoring, status	2325
	R. Tanaka, Y. Furukawa, T. Hirono, M. Ishii, M. Kago, A. Kiyomichi, T. Masuda, T. Matsumoto, T. Matsushita, T. Ohata, C. Saji, T. Sugimoto, M. Yamaga, A. Yamashita JASRI/SPring-8, Hyogo-ken, Japan T. Fukui, T. Hatsui, N. Hosoda, T. Ohshima, T. Otake, Y. Otake, H. Takebe RIKEN/SPring-8, Hyogo, Japan H. Maesaka RIKEN Spring-8 Harima, Hyogo, Japan
	The control system design of the X-ray free electron laser facility (SACLA) in SPring-8 has started in 2006. Now, the facility has completed to start beam commissioning in February 2011. The electron beams were successfully accelerated up to 8 GeV and the first SASE X-ray was observed. The control system adopts the 3-tier standard model by using MADOCA framework developed in SPring-8. The upper control layer consists of Linux PCs for operator consoles, Sybase RDBMS for data logging and FC-based NAS for NFS. The lower layer consists of VMEbus systems with off-the-shelf I/O boards and specially developed boards for RF waveform processing with high precision. Solaris OS is adopted to operate VMEbus CPU. The PLC is used for slow control and connected to the VME systems via FL-net. The Device-net is adopted for frontend device control to reduce the number of signal cables. Some of VMEbus systems have a beam-synchronized data-taking system to meet 60Hz electron beam operation for the beam tuning diagnostics. The accelerator control system has gateways not only to monitor device status but also control the tuning points of the facility utility system, especially cooling water.

WEPS033	Matching a Laser Driven Proton Injector to a CH - Drift Tube Linacs	proton, solenoid, acceleration, electron	2556
	A. Almomani, M. Droba, U. Ratzinger IAP, Frankfurt am Main, Germany I. Hofmann HIJ, Jena, Germany
	Experimental results and theoretical predictions in laser acceleration of protons achieved energies of ten to several tens of MeV. The LIGHT project (Laser Ion Generation, Handling and Transport) is proposed to use the PHELIX laser accelerated protons and to provide transport, focusing and injection into a conventional accelerator. This study demonstrates transport and focusing of laser-accelerated 10 MeV protons by a pulsed 18 T magnetic solenoid. The effect of co-moving electrons on the beam dynamics is investigated. The unique features of the proton distribution like small emittances and high yield of the order of 10¹3 protons per shot open new research area. The possibility of creating laser based injectors for ion accelerators is addressed. With respect to transit energies, direct matching into DTL's seems adequate. The bunch injection into a proposed CH⁻ structure is under investigation at IAP Frankfurt. Options and simulation tools are presented.

WEPZ002	Chromatic, Geometric and Space Charge Effects on Laser Accelerated Protons Focused by a Solenoid	solenoid, proton, emittance, ion	2766
	H.Y. Al-Omari, U. Ratzinger IAP, Frankfurt am Main, Germany I. Hofmann GSI, Darmstadt, Germany
	We studied numerically emittance and transmission effects by chromatic and geometric aberrations, with and without space charge, for a proton beam behind a solenoid in the laser proton experiment LIGHT at GSI. The TraceWin code was employed using a field map for the solenoid and an initial distribution with exponential energy dependence close to the experiment. The results show a strong effect of chromatic, and a relatively weak one of geometric aberrations as well as dependence of proton transmission on distance from the solenoid. The chromatic effect has an energy filtering property due to the finite radius beam pipe. Furthermore, a relatively modest dependence of transmission on space charge is found for p production intensity below 10¹1.

WEPZ005	Field Calculations to obtain Attosecond/Femtosecond Electron Bunches	cathode, electron, injection, radiation	2772
	V.A. Papadichev LPI, Moscow, Russia
	Obtaining short electron bunches of attosecond and femtosecond duration in a combined quasi-static and laser electric field [* - ***] requires careful field formation in the cathode region. First, the maximum of laser electric field normal to the cathode plate, depending on the incidence angle, was found employing Fresnel formulae using complex dielectric permittivity of metals. Second, laser field enhancement on cathode spikes was calculated for the case of an ellipsoid in a qusi-static approximation (laser wavelength larger than spike dimensions). Field enhancement is approximately proportional to the square of the ratio of major to minor axes of ellipsoid. Thus, enhancement factors as large as 100 - 1000 are obtainable, allowing to reduce laser power by 10 thousand to 1 million times. V.A.Papadichev, Patent RU 2 269 877 C1, 10.02.06, Bull. 4. V.A.Papadichev, Proc. EPAC08, p.2812. * V.A.Papadichev, Proc. EPAC08, p.2815. **** V.A.Papadichev, Proc. IPAC'10, p. 4372

WEPZ006	Forming Attosecond Electron Pulses in Space-charge Dominated Regime	electron, radiation, acceleration, bunching	2775
	V.A. Papadichev LPI, Moscow, Russia
	Production of high-current attosecond electron pulses requires studying of the final bunching stage, which inevitably is space-charge dominated [, , *]. Two models are studied, both allow solving a one-dimensional equation of motion. The first is for a spherical bunch, which corresponds to a short emitted pulse from a one-spike cathode of diameter approximately equal to its length. The second model is suited for pulses emitted from a multi-spike or multi-blade cathode. The bunch in the latter case is a thin plate and its evolution can be studied by also solving one-dimensional equation of motion. It was shown that bunches of 10-attosecond (as) duration with peak current of dozens of amperes can be obtained when using a carbon dioxide laser and less than 0.1-as duration with currents up to 1 MA when employing a neodymium laser. Beam focusing in transverse directions is also studied using a model. Possible applications of such electron bunches are reviewed, including obtaining attosecond pulses of tunable coherent radiation in UV and X-ray regions. V.A.Papadichev, Proceedings of EPAC08, p.2815. V.A.Papadichev, Proceedings of IPAC'10, Kyoto, Japan, p. 4372. * V.A.Papadichev, Proc. RUPAC-2010, TUPSAO10, p. 56.

WEPZ010	Modeling and Experimental Update on Direct Laser Acceleration	electron, plasma, acceleration, simulation	2787
	I. Jovanovic, M.W. Lin Penn State University, University Park, Pennsylvania, USA
	Funding: This work is supported by the Defense Threat Reduction Agency under contract HDTRA1-11-1-0009. Moderate-energy, high-repetition-rate electron beams are needed in a variety of applications such as those in security and medicine, while requiring that the acceleration be realized in a compact and relatively inexpensive package. Laser wakefield acceleration is an attractive technology which meets most of those requirements, but it requires the use of relatively high peak power lasers which do not scale readily to high repetition rates. We are developing the theoretical and experimental basis for advancing the science and technology of direct laser acceleration (DLA) of charged particles using the axial component of the electric field of a radially polarized intense laser pulse. DLA is an acceleration method which exhibits no threshold and is thus compatible with the use of lower peak power, but much higher repetition rate lasers. We are currently numerically investigating the conditions for quasi-phase-matched DLA of electrons in plasma waveguides and experimentally implementing the quasi-phase-matched waveguide structure in laser-produced plasmas.

WEPZ011	Fast Cooling of Bunches in Compton Storage Rings	electron, emittance, scattering, photon	2790
	E.V. Bulyak NSC/KIPT, Kharkov, Ukraine J. Urakawa KEK, Ibaraki, Japan F. Zimmermann CERN, Geneva, Switzerland
	We propose an enhancement of laser radiative cooling by utilizing laser pulses of small spatial and temporal dimensions, which interact only with a fraction of an electron bunch circulating in a storage ring. We studied the dynamics of such electron bunch when laser photons scatter off the electrons at a collision point placed in a section with nonzero dispersion. In this case of ‘asymmetric cooling', the stationary energy spread is much smaller than under conditions of regular scattering where the laser spot size is larger than the electron beam; and the synchrotron oscillations are damped faster. Coherent oscillations of large amplitude may be damped within one synchrotron period, so that this method can support the rapid successive injection of many bunches in longitudinal phase space for stacking purposes. Results of extensive simulations are presented for the performance optimization of Compton gamma-ray sources and damping rings.

WEPZ016	Generation and Characterization of Electron Bunches with Ramped Current Profiles at the FLASH Facility	electron, wakefield, linac, free-electron-laser	2805
	P. Piot Fermilab, Batavia, USA C. Behrens, C. Gerth, M. Vogt DESY, Hamburg, Germany F. Lemery, D. Mihalcea Northern Illinois University, DeKalb, Illinois, USA
	Funding: This work was supported the Defense Threat Reduction Agency, Basic Research Award # HDTRA1-10^-1-0051, to Northern Illinois University and the German's Bundesministerium f\"ur Bildung und Forschung We report on the successful generation of electron bunches with current profiles that have a quasi-linear dependency on the longitudinal coordinate. The technique relies on impressing nonlinear correlations in the longitudinal phase space using a linac operating at two frequencies (1.3 and 3.9 GHz) and a bunch compressor. Data taken for various accelerator settings demonstrate the versatility of the method. The produced bunches have parameters well matched to drive high-gradient accelerating field with enhanced transformer ratio in beam-driven accelerators based on sub-mm-sizes dielectric or plasma structures.

WEPZ021	Self-Consistent Dynamics of Electromagnetic Pulses and Wakefields in Laser-Plasma Interactions	plasma, wakefield, simulation, space-charge	2811
	A. Bonatto, R. Pakter, F.B. Rizzato IF-UFRGS, Porto Alegre, Brazil
	In the present work we study the stability of laser pulses propagating in a cold relativistic plasma, which can be of interest for particle acceleration schemes. After obtaining a Lagrangian density from the one-dimensional equations for the laser pulse envelope and the plasma electron density, we define a trial function and apply the variational approach in order to obtain an analytical model which allows us to calculate an effective potential for the pulse width. Using this procedure, we analyze the stability of narrow and large laser pulses and then compare its results with numerical solutions for the envelope and density equations.

WEPZ025	Study of Self-injection of an Electron Beam in a Laser-driven Plasma Cavity	electron, plasma, simulation, injection	2820
	S. Krishnagopal, S.A. Samant, D. Sarkar BARC, Mumbai, India P. Jha Lucknow University, Lucknow, India A.K. Upadhyay CBS, Mumbai, India
	Over the last few years, remarkable advances in laser wakefield acceleration of electrons have been achieved, including quasi-monoenergetic beams and GeV energy in a few centimeters. However, it is necessary to achieve good beam quality (large current, low energy-spread and low emittance) for applications such as free-electron lasers. We study self-injection in two regimes of the laser-plasma interaction: the moderate intensity, self-guiding regime, and the low intensity, near-injection-threshold regime, both in a homogeneous plasma that completely fills the simulation volume. We find good beam quality with injection of on-axis electrons, especially at lower intensity. We also study the case when the laser has to travel through vacuum before entering the plasma. We find that injection here is completely different, from off-axis electrons, and the beam quality is poorer.

WEPZ027	Stabilization of the LWFA and its Application to the Single-shot K-edge Densitometry	electron, scattering, emittance, wakefield	2823
	K. Koyama, H. Madokoro, Y. Matsumura University of Tokyo, Tokyo, Japan R. Kuroda, K. Yamada AIST, Tsukuba, Ibaraki, Japan H. Masuda, M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan S. Masuda Osaka University, Suita, Osaka, Japan
	Funding: This work was supported in part by Global COE Program “Nuclear Education and Research Initiative,” MEXT, Japan Injection of electrons into a laser wakefield accelerator (LWFA) via a wavebreaking process was investigated in order to obtain stable output of electron bunches. A density down ramp for occurring the wavebreaking was formed by an oblique shockwave, which was excited by setting a little flow-deflector on an edge of the supersonic nozzle of high-Mach number (M=5). Parameters of the jet were examined by using PIC code and evaluated by using an interferometer, the density was 10¹⁹cm^-3, density ratio was 2, and the characteristic length was 70 microns. Injection experiments using 7-TW laser pulses suggested that electrons were injected in the density ramp. Since the all-optical Compton X-ray is attractive source for an accurate densitometry, a preliminary experiment of a single-shot K-edge densitometry was performed by using X-ray pulses generated by the laser-Compton scattering (LCS) device based on a compact S-band 40 MeV linac at AIST. The single-shot K-edge densitometry was also applicable to evaluate the transverse emittance of electron bunches.

WEPZ030	Study on a Gas-filled Capillary Waveguide for Laser Wakefield Acceleration	simulation, acceleration, electron, plasma	2829
	M.S. Kim, D. Jang, D. Jang, H. Suk APRI-GIST, Gwangju, Republic of Korea
	In gas-filled capillary waveguide for lase wakefield accelerators the gas flows through the two gas feed lines used to sustain constant pressure. Compared to the supersonic gas-jet system operated under high pressure, the gas at low pressure (<1atm) is injected inside capillary waveguide, so that this waveguide has experimental limit to the measurement of the neutral density. In order to investigate the gas pressure in capillary system we used computational fluid dynamics (CFD) simulation. In this paper, we presented the gas pressure changed by a variety of parameters, such as length and sizes of gas feed lines, and the method to decrease the turbulence effect at the ends of capillary.

WEPZ031	Accelerator Studies on a Possible Experiment on Proton-driven Plasma Wakefields at CERN	plasma, proton, electron, acceleration	2832
	R.W. Assmann, I. Efthymiopoulos, S.D. Fartoukh, G. Geschonke, B. Goddard, C. Heßler, S. Hillenbrand, M. Meddahi, S. Roesler, F. Zimmermann CERN, Geneva, Switzerland A. Caldwell, G.X. Xia MPI-P, München, Germany P. Muggli MPI, Muenchen, Germany
	There has been a proposal by Caldwell et al to use proton beams as drivers for high energy linear colliders. An experimental test with CERN's proton beams is being studied. Such a test requires a transfer line for transporting the beam to the experiment, a focusing section for beam delivery into the plasma, the plasma cell and a downstream beam section for measuring the effects from the plasma and safe disposal of the beam. The work done at CERN towards the conceptual layout and design of such a test area is presented. A possible development of such a test area into a CERN test facility for high-gradient acceleration experiments is discussed.

WEPZ034	Double Resosnant Plasma Wakefields	plasma, simulation, wakefield, electron	2838
	B.D. O'Shea, A. Fukasawa, B. Hidding, J.B. Rosenzweig, S. Tochitsky UCLA, Los Angeles, California, USA D.L. Bruhwiler Tech-X, Boulder, Colorado, USA
	Present work in Laser Plasma Accelerators focuses on a single laser pulse driving a non-linear wake in a plasma. Such single pulse regimes require ever increasing laser power in order to excite ever increasing wake amplitudes. Such high intensity pulses can be limited by instabilities as well engineering restrictions and experimental constraints on optics. Alternatively we present a look at resonantly driving plasmas using a laser pulse train. In particular we compare analytic, numerical and VORPAL simulation results to characterize a proposed experiment to measure the wake resonantly driven by four Gaussian laser pulses. The current progress depicts the interaction of 4 CO2 laser pulses, λlaser = 10.6μm, of 3 ps full width at half max- imum (FWHM) length separated peak-to-peak by 18 ps, each of normalized vector potential a0 ≃ 0.7. Results con- firm previous discourse (,) and show, for a given laser pro- file, an accelerating field on the order of 900 MV/m, for a plasma satisfying the resonant condition, ωp=π/t_fwhm. Umstadter, D., et al, Phys. Rev. Lett. 72, 1224 ** Umstadter, D., et al, Phys. Rev. E 51, 3484

THYB01	Advanced Beam Manipulation Techniques at SPARC	gun, emittance, linac, simulation	2877
	A. Mostacci, D. Alesini, P. Antici, A. Bacci, M. Bellaveglia, R. Boni, M. Castellano, E. Chiadroni, G. Di Pirro, A. Drago, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, E. Pace, A.R. Rossi, B. Spataro, C. Vaccarezza INFN/LNF, Frascati (Roma), Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy B. Marchetti INFN-Roma II, Roma, Italy M. Migliorati University of Rome "La Sapienza", Rome, Italy L. Palumbo Rome University La Sapienza, Roma, Italy V. Petrillo, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy C. Ronsivalle ENEA C.R. Frascati, Frascati (Roma), Italy
	SPARC in Frascati is a high brightness photo-injector used to drive Free Electron Laser experiments and explore advanced beam manipulation techniques. The R&D effort made for the optimization of the beam parameters will be presented here, together with the major experimental results achieved. In particular, we will focus on the generation of sub-picosecond, high brightness electron bunch trains via velocity bunching technique (the so called comb beam). Such bunch trains can be used to drive tunable and narrow band THz sources, FELs and plasma wake field accelerators.
	Slides THYB01 [20.772 MB]

THPC007	Laser Electron Interaction Simulation for the Femtosecond Bunch Slicing on SOLEIL Storage Ring	electron, wiggler, simulation, storage-ring	2918
	J.F. Zhang, M.-E. Couprie, M. Labat, A. Loulergue, A. Nadji SOLEIL, Gif-sur-Yvette, France
	The interaction of an electron bunch and a laser in a wiggler (modulator) to generate a femtosecond slice is simulated for the slicing project on SOLEIL storage ring, using a code based on Monte-Carlo method and GENESIS. The results from these two codes are consistent with the theoretical values. The maximum modulated energy of the electron bunch and the number of electrons above a certain limit are studied for different wiggler and laser parameters. The transport of the 6D distribution of the sliced bunch from the modulator to the radiators are simulated using AT (Accelerator Toolbox) and ELEGANT, with synchrotron radiation on and taking into account the collective effects of the sliced bunch core.

THPC015	A Dedicated THz Beamline at DELTA	electron, radiation, simulation, undulator	2939
	M. Höner, M. Bakr, H. Huck, S. Khan, R. Molo, A. Nowaczyk, A. Schick, P. Ungelenk, M. Zeinalzadeh DELTA, Dortmund, Germany
	Funding: Work supported by DFG, BMBF, and by the Federal State NRW As a consequence of the new radiation source for ultrashort VUV pulses at DELTA, which is based on the interaction of electrons with fs laser pulses, coherent THz radiation is emitted. Simulations of the laser-electron interaction, particle dynamics and radiation spectrum, as well as the optical and mechanical design of a dedicated THz beamline are presented. First experimental results including laser-electron overlap diagnostics and characterization of the THz radiation are discussed.

THPC016	Ultrashort VUV and THz Pulse Generation at the DELTA Storage Ring	electron, undulator, radiation, klystron	2942
	A. Schick, M. Bakr, H. Huck, M. Höner, S. Khan, R. Molo, A. Nowaczyk, P. Ungelenk, M. Zeinalzadeh DELTA, Dortmund, Germany
	Funding: Supported by DFG, BMBF, and the Federal State NRW The optical klystron (two undulators, separated by a dispersive section) at DELTA, formerly operated as storage-ring FEL, is seeded with ultrashort pulses from a Ti:Sapphire laser. The thus induced energy modulation of an electron bunch in the first undulator is converted to a density modulation within the dispersive chicane. In the second undulator, the micro-bunched electrons emit ultrashort pulses coherently at harmonics of the fundamental laser wavelength. Additionally, coherent ultrashort THz pulses are generated several meters downstream of the optical klystron by the laser-induced gap in the electron bunch. First results are presented.

THPC017	Temporal and Spatial Alignment of Electron Bunches and Ultrashort Laser Pulses for the CHG Experiment at DELTA	electron, undulator, controls, synchrotron	2945
	M. Zeinalzadeh, M. Bakr, H. Huck, M. Höner, S. Khan, R. Molo, A. Nowaczyk, A. Schick, P. Ungelenk DELTA, Dortmund, Germany
	Funding: Supported by DFG, BMBF, and the Federal State NRW The generation of ultrashort VUV pulses by CHG (Coherent Harmonic Generation) requires achieving and maintaining the longitudinal and transversal overlap of femtosecond laser pulses and electron bunches. We present the techniques and the experimental setup applied at the DELTA storage ring. For the longitudinal analysis, both a streak camera and a fast photo diode are used. Transversely, two CCD cameras acquire images of laser and synchrotron light at different positions inside of the undulator. A feedback system utilizes the intensity of a THz signal generated several meters downstream of the undulator to optimize and maintain the overlap.

THPC042	Status and Development of the SAGA Light Source	storage-ring, controls, undulator, linac	2996
	T. Kaneyasu, Y. Iwasaki, S. Koda, Y. Takabayashi SAGA, Tosu, Japan
	The SAGA Light Source (SAGA-LS) is a synchrotron radiation facility consisting of a 255 MeV injector linac and a 1.4 GeV storage ring, and has been stably providing synchrotron light since 2006. The annual failure time is less than 1% of the user time in the recent two years. Three insertion devices are installed in the storage ring: an APPLE-II undulator, a planar type undulator (Saga Univ.) and a 4 T superconducting wiggler (SCW). The SCW contains a hybrid three-pole magnet; the main pole of the magnet is surrounded by superconducting coils while side poles are normal conducting magnets. The main pole of the SCW is cooled by a GM cryocooler, which allows the SCW be operated without liquid helium. Since the installation in March 2010, the SCW has been operated stably. To control the ID parameters during the user time, a feed-forward correction system which minimizes the ID effects on the emittance coupling was developed. The laser Compton Gamma-rays were generated by using a CO2 laser and were used for beam energy measurement. In addition, research works on the beam lifetime and interaction between electron beam and crystal, and development of a multipole magnet are in progress.

THPC053	Shanghai Soft X-Ray Free Electron Laser Test Facility	radiation, linac, FEL, electron	3011
	Z.T. Zhao SINAP, Shanghai, People's Republic of China
	As a critical development step towards constructing a hard X-ray FEL in China, a soft X-ray FEL test facility (SXFEL) was proposed and will be constructed at the SSRF campus by a joint team of Institute of Tsinghua University and Shanghai Institute of Applied Physics. This test facility, based on an 840MeV electron linear accelerator, aims at generating 9nm FEL radiation with two-stage cascaded HGHG scheme. The project proposal was approved in February 2011 by central government, and the constrction is expected to start in early 2012. This paper describes the preliminary design of this soft X-ray test facility and the R&D progress of the key FEL technologies in the SDUV-FEL test bench.

THPC079	Echo-enabled Harmonic Generation at DELTA	undulator, electron, bunching, storage-ring	3074
	R. Molo, M. Bakr, H. Huck, M. Höner, S. Khan, A. Nowaczyk, A. Schick, P. Ungelenk, M. Zeinalzadeh DELTA, Dortmund, Germany
	Funding: Supported by DFG, BMBF, and the Federal State NRW We present conceptual studies of the realization of the echo-enabled harmonic generation (EEHG) technique proposed by G. Stupakov* as an upgrade of the present coherent harmonic generation (CHG) project at the DELTA storage ring*. EEHG allows to reach shorter wavelengths compared to the CHG scheme. In addition to the optical klystron used for CHG, a third undulator is needed for a second energy modulation of the electron bunch, followed by an additional strong dispersive section. Installing these insertion devices requires a new long straight section in the storage ring and a new lattice configuration. G. Stupakov Phys. Rev. Lett. 10², 074801 (2009) ** A. Schick et al., this conference

THPC081	Status of the Free-Electron Laser FLASH at DESY	FEL, undulator, photon, radiation	3080
	M. Vogt, B. Faatz, J. Feldhaus, K. Honkavaara, S. Schreiber, R. Treusch DESY, Hamburg, Germany
	The free-electron laser facility FLASH at DESY, Germany has been upgraded in 2010. Now, FLASH delivers an electron beam energy up to 1.25 GeV. The longitudinal phase-space is linearized by 3.9 GHz superconducting cavities. The facility delivers to users ultra-short laser like radiation pulses in the range of less than 50 fs to 200 fs in the soft X-ray wavelenth range from 44 down to 4.1 nm. FLASH provides hundreds to thousands pulses per second to users with unprecedented peak brilliance. FLASH will be upgraded with a second undulator beam line and an additional experimental hall. Construction starts Autumn 2011. We summarize the operational status of the ongoing 3rd user period.

THPC083	Analysis of Parameter Space of a Kilowatt-scale Free Electron Laser for Extreme Ultraviolet Lithography Driven by L-band Superconducting Linear Accelerator Operating in a Burst Mode	electron, radiation, FEL, undulator	3086
	E. Schneidmiller, V. Vogel, H. Weise, M.V. Yurkov DESY, Hamburg, Germany
	The driving engine of the Free Electron Laser in Hamburg (FLASH) is an L-band superconducting accelerator. It is designed to operate in a burst mode with 800 microsecond pulse duration at a repetition rate of 10 Hz. The maximum accelerated beam current during the macropulse is 10 mA. In this paper we analyze the parameter space for optimum operation of the FEL at the wavelength of 13.5 nm and 6.7 nm. Our analysis shows that the FLASH technology holds great potential for increasing the average power of the linear accelerator and an increase of the conversion efficiency of the electron kinetic energy to the light. Thus, it will be possible to construct a FLASH like free electron laser with an average power up to 3 kW. Such a source meets the requirements of the light source for the next generation lithography.

THPC087	Saturation Effect on VUV Coherent Harmonic Generation at UVSOR-II	electron, simulation, FEL, bunching	3098
	T. Tanikawa, M. Adachi, M. Katoh, J. Yamazaki, H. Zen UVSOR, Okazaki, Japan M. Hosaka, Y. Taira, N. Yamamoto Nagoya University, Nagoya, Japan
	Light source technologies based on laser seeding are under development at the UVSOR-II electron storage ring. In the past experiments, we have succeeded in generating coherent harmonics (CHs) in deep ultraviolet (UV) and vacuum UV (VUV) region and also in generating CH with variable polarizations in deep UV. In previous conference, we reported an introduction of new-constructed spectrometer for VUV and results of spectra measurement, undulator gap dependence, and injection laser power dependence on VUV CHs. This time we have successfully observed saturation on CHs intensities　and have found some interesting phenomena in different harmonic orders. In this conference, we will discuss the results of some systematic measurements and those analytical and particle tracking simulations*. M. Labat et al., Phys. Rev. Lett. 10¹ (2008) 164803. T. Tanikawa et al., Proc. IPAC'10, TUPE029, p. 2206 (2010). *T. Tanikawa et al., Appl. Phys. Express 3 (2010) 122702.

THPC093	Beam Dynamics Simulations for the SwissFEL Injector Test facility	emittance, solenoid, simulation, gun	3107
	S. Bettoni, M. Pedrozzi, S. Reiche, T. Schietinger PSI, Villigen, Switzerland
	The SwissFEL under study at PSI will produce 0.1 nm to 0.7 nm wavelength coherent x-ray. The design of the injector is based on the invariant envelope matching scheme, developed for other photoinjectors in the past years. According to this technique the emittance at the exit of the injector can be minimized if some conditions at the entrance of the booster are satisfied. A campaign of simulations has been carried out to verify the impact of the errors of the machine components (RF and magnetic) and laser shaping (transverse and longitudinal) on the final SwissFEL injector emittance. These results have to be used to define the tolerances on the machine and laser.

THPC095	Commissioning Status of the SwissFEL Injector Test Facility	emittance, solenoid, gun, electron	3110
	T. Schietinger, M. Aiba, S. Bettoni, B. Beutner, A. Falone, R. Ganter, R. Ischebeck, F. Le Pimpec, N. Milas, G.L. Orlandi, M. Pedrozzi, E. Prat, S. Reiche, C. Vicario PSI, Villigen, Switzerland
	The SwissFEL injector test facility at the Paul Scherrer Institute has been in operation since August 2010. Its primary goal is the demonstration of a high-brightness electron beam as it will be required to drive the SwissFEL main linac. The injector further serves as a platform for the development and validation of accelerator components needed for the SwissFEL project. We give an overview of recent commissioning activities at about 130 MeV beam energy, with particular emphasis on results from optics matching studies and emittance measurements, the latter obtained with different optics-based methods. A five-cell transverse-deflecting cavity allows studies of the longitudinal bunch charge distribution and slice emittance. Bunch length measurements will become the focus of interest after the installation of a magnetic compression chicane, currently scheduled for the summer of 2011.

THPC096	Soft X-ray Free-electron Laser with a 10-time Reduced Size	electron, undulator, FEL, bunching	3113
	Y.-C. Huang, F.H. Chao, C.H. Chen, K.Y. Huang NTHU, Hsinchu, Taiwan P.J. Chou NSRRC, Hsinchu, Taiwan
	Funding: This work is supported by National Science Council under Contract NSC 99-2112-M-007 -013 -MY3. We present a 30-m long soft x-ray FEL consisting of a 5-MeV photoinjector, a 150 MeV linac, a magnetic chicane compressor, and a 3-m long undulator. We employ both the 3rd and the 4th harmoincs of a Nd laser at 355 and 266 nm, respectively, to illuminate the cathode of the photoinjector. Owing to the beating of the two lasers, the emitted electron beam is modulated at 282 THz. The electrons are further accelerated to 150 MeV and, after acceleration, compressed by 33 times in a magnetic chicane. The temporal compression of the electron macropulse increases the electron bunching frequency to 9.3 PHz, corresponding to a soft x-ray wavelength of 32.2 nm. We adopt a solenoid-derived staggered array undulator* with a 3-m length, 5 mm undulator period, and 1.2 mm gap. With a solenoid field of 10 kG, we estimate an undulator parameter of 0.4 and a corresponding radiation wavelength of 32.2 nm for a 150 MeV driving beam. With 3.3-kA peak current, 0.03% energy spread, 2 mm-mrad emittance, and 80-micron beam radius at the undulator entrance, the GENESIS code predicts 0.2 GW radiation power from the 3-m long undulator for an initial bunching factor of merely 10 ppm. * Y.C. Huang, H.C. Wang, R.H. Pantell, and J. Feinstein, "A staggered-array wiggler for far infrared, free-electron laser operation," IEEE J. Quantum Electronics 30 (1994) 1289.

THPC097	Transverse Alignment Tolerances for the European XFEL Laser Heater	electron, FEL, undulator, emittance	3116
	V.A. Goryashko NASU/IRE, Kharkov, Ukraine M. Dohlus DESY, Hamburg, Germany M. Hamberg, V.G. Ziemann Uppsala University, Uppsala, Sweden
	Funding: Supported by the KTH-SU-UU FEL Center. We study the impact of misalignments between a laser beam and an electron bunch on the energy distribution function of the electron bunch in the laser heater. Transverse position and angular misalignment as well as different spot size of the laser and electron beam are considered. We find that the transverse misalignment makes the energy distribution function narrower compared to the case of ideal adjustment and a distinct peak in the distribution around the initial mean value of the energy appears. We demonstrate that despite these misalignments a uniform heating in terms of the energy spread can be achieved by appropriately adapting the transverse size and power of the laser beam such that the energy distribution function of the electron bunch at the end of the laser heater can be made similar to a Gaussian, thus providing more effective Landau damping against the micro-bunching instability. The laser power mainly determines the local energy spread while the laser spot size governs the shape of the energy distribution function. The transverse oscillations of electrons induced by the magnetic field in the laser heater are found to be non-essential for typical operation parameters.

THPC100	Full Temporal Reconstruction using an Advanced Longitudinal Diagnostic at the SPARC FEL	FEL, diagnostics, radiation, undulator	3119
	G. Marcus, J.B. Rosenzweig UCLA, Los Angeles, California, USA M. Artioli, F. Ciocci, L. Giannessi, A. Petralia, M. Quattromini, V. Surrenti ENEA C.R. Frascati, Frascati (Roma), Italy A. Bacci, M. Bellaveglia, E. Chiadroni, G. Di Pirro, M. Ferrario, G. Gatti, A. Mostacci, A.R. Rossi INFN/LNF, Frascati (Roma), Italy A. Cianchi INFN-Roma II, Roma, Italy V. Petrillo Istituto Nazionale di Fisica Nucleare, Milano, Italy J.V. Rau ISM-CNR, Rome, Italy
	The Production of ultra-short (sub 100 fs) single-spike radiation possessing full longitudinal coherence from a free-electron laser (FEL) has been the subject of intense study. A Frequency-Resolved Optical Gating (FROG) diagnostic has been developed and tested at UCLA, which has the capability of providing a longitudinal reconstruction of these ultra-fast pulses. This paper reports the results of the application of the diagnostic at the SPARC FEL facility.

THPC104	Optimization for Single-Spike X-Ray Fels at LCLS with a Low Charge Beam	undulator, FEL, simulation, electron	3131
	L. Wang, Y.T. Ding, Z. Huang SLAC, Menlo Park, California, USA
	The recently commissioned Linac Coherent Light Source is an x-ray free-electron laser at the SLAC National Accelerator Laboratory, which is now operating at x-ray wavelengths of 20-1.2 Angstrom with peak brightness nearly ten orders of magnitude beyond conventional synchrotron sources. At the low charge operation mode (20 pC), the x-ray pulse length can be <10 fs. In this paper we report our numerical optimization and simulations to produce even shorter x-ray pulses by optimizing the machine and undulator setup. In the soft x-ray regime, with the help of slotted-foil or undulator taper, a single spike x-ray pulse is achievable with peak FEL power of 30 GW.

THPC109	First Demonstration of Electron Beam Generation and Characterization with an All Superconducting Radio-frequency (SRF) Photoinjector*	cavity, SRF, cathode, solenoid	3143
	T. Kamps, W. Anders, R. Barday, A. Jankowiak, J. Knobloch, O. Kugeler, A.N. Matveenko, A. Neumann, T. Quast, J. Rudolph, S.G. Schubert, J. Völker HZB, Berlin, Germany P. Kneisel JLAB, Newport News, Virginia, USA R. Nietubyc The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock, Poland J.K. Sekutowicz DESY, Hamburg, Germany J. Smedley BNL, Upton, Long Island, New York, USA V. Volkov BINP SB RAS, Novosibirsk, Russia G. Weinberg FHI, Berlin, Germany I. Will MBI, Berlin, Germany
	Funding: Work supported by Bundesministerium für Bildung und Forschung und Land Berlin. The work on the Pb cathode film is supported by EuCARD Grant Agreement No. 227579 In preparation for a high brightness, high average current electron source for the energy-recovery linac BERLinPro an all superconducting radio-frequency photoinjector is now in operation at Helmholtz-Zentrum Berlin. The aim of this experiment is beam demonstration with a high brightness electron source able to generate sub-ps pulse length electron bunches from a superconducting (SC) cathode film made of Pb coated on the backwall of a Nb SRF cavity. This paper describes the setup of the experiment and first results from beam measurements.

THPC111	Operation of an L-band RF Gun with Pulses Inside the Burst Mode RF Pulse	gun, cavity, klystron, controls	3146
	V. Vogel, V. Ayvazyan, B. Faatz, K. Flöttmann, D. Lipka, P. Morozov, H. Schlarb, S. Schreiber DESY, Hamburg, Germany
	The Free-Electron Laser in Hamburg (FLASH) is a user facility since 2005, delivering femtosecond short radiation pulses in the wavelength range between 4.1 and 44 nm using the SASE principle. In FLASH, the electron beam is accelerated to 1.25 GeV with L-band superconducting cavities. The electron source is a normal conducting RF-gun photoinjector. The L-band standing wave RF gun has one and a half cells. The gun is operated in burst mode with an RF pulse length of up to 900 microseconds and a repetition rate of 10 Hz. Several hundreds to thousands of bunches are accelerated per second. With 5 MW of pulsed forward power, the dissipated power inside the RF gun is 45 kW. In this paper we propose an operational mode which allows us to reduce the dissipated power to ease operation or to increase the effective duty cycle in the gun by pulsing the gun within one burst. We report on first experimental results at FLASH, where an RF burst of 46μRF-pulses with a length of 10 microseconds separated by 10 microseconds has been successfully generated reducing the dissipated power by a factor of 2.

THPC113	Slice Emittance Measurements for Different Bunch Charges at PITZ	emittance, solenoid, electron, booster	3149
	Ye. Ivanisenko, H.-J. Grabosch, M. Gross, L. Hakobyan, G. Klemz, M. Krasilnikov, M. Mahgoub, D. Malyutin, A. Oppelt, M. Otevřel, B. Petrosyan, D. Richter, S. Rimjaem, A. Shapovalov, F. Stephan, G. Vashchenko, S. Weidinger DESY Zeuthen, Zeuthen, Germany G. Asova INRNE, Sofia, Bulgaria I.I. Isaev MEPhI, Moscow, Russia M.A. Khojoyan YerPhI, Yerevan, Armenia I.H. Templin, I. Will MBI, Berlin, Germany
	The successful operation of the Free electron LASer in Hamburg (FLASH) at DESY brings up the interest in further broadening the spectrum of possible applications also for the upcoming European XFEL. Hence the electron beam properties required for lasing should be tested and optimized for a broad range of values already on the level of the injector. The Photo Injector Test facility in Zeuthen (PITZ) at DESY characterizes the photo injectors for FLASH and the European XFEL. The main study involves the transverse projected emittance optimization for different beam conditions. Beside the projected emittance, the PITZ setup allows to measure the transverse emittance with a sub-bunch longitudinal resolution. This slice emittance diagnostics is based on the usage of bunches with an energy correlation of the longitudinal phase space components induced by the booster. Then the bunch is swept vertically with a dipole magnet. Part of the bunch that corresponds to a longitudinal slice is cut out by means of a vertical slit and the horizontal emittance is measured. This report presents the results of recent slice emittance measurements for different bunch charges.

THPC114	High Brightness Photo Injector Upgrade and Experimental Optimization at PITZ	emittance, electron, gun, booster	3152
	M. Krasilnikov, H.-J. Grabosch, M. Gross, Ye. Ivanisenko, G. Klemz, W. Köhler, M. Mahgoub, D. Malyutin, A. Oppelt, M. Otevřel, B. Petrosyan, S. Rimjaem, F. Stephan, G. Vashchenko, S. Weidinger, R.W. Wenndorff DESY Zeuthen, Zeuthen, Germany G. Asova INRNE, Sofia, Bulgaria L. Hakobyan, M.A. Khojoyan YerPhI, Yerevan, Armenia M. Hoffmann, H. Schlarb DESY, Hamburg, Germany I.I. Isaev, A. Shapovalov MEPhI, Moscow, Russia M.A. Nozdrin JINR, Dubna, Moscow Region, Russia D. Richter HZB, Berlin, Germany I.H. Templin, I. Will MBI, Berlin, Germany
	The photo injector test facility at DESY in Zeuthen (PITZ) develops and optimizes electron sources for linac driven free electron lasers. The main goal of PITZ is to demonstrate a small electron beam emittance by tuning several main parameters of the injector - photo cathode laser pulse, rf gun with solenoids and booster cavity parameters. A slit scan technique is used to measure the transverse phase space of the electron beam and the projected normalized emittance. The photo injector is capable of pulse train production which can be measured with dedicated diagnostics at PITZ. This enables optimization of the beam emittance for a wide range of bunch charges from tens of pC to several nC while keeping high resolution of beam measurements. The results of the experimental optimization will be presented yielding a new benchmark of photo injector performance.

THPC115	Emittance Optimization for Different Bunch Charges with Upgraded Setup at PITZ	emittance, gun, booster, electron	3155
	G. Vashchenko, G. Asova, M. Gross, L. Hakobyan, I.I. Isaev, Ye. Ivanisenko, M.A. Khojoyan, M. Krasilnikov, M. Mahgoub, D. Malyutin, M. Otevřel, B. Petrosyan, S. Rimjaem, A. Shapovalov, F. Stephan, S. Weidinger DESY Zeuthen, Zeuthen, Germany M.A. Nozdrin JINR, Dubna, Moscow Region, Russia D. Richter HZB, Berlin, Germany I.H. Templin, I. Will MBI, Berlin, Germany
	The Photo Injector Test facility at DESY, Zeuthen site, (PITZ) has the aim to develop and optimize high brightness electron sources for Free Electron Lasers like FLASH and the European XFEL. Photo electrons emitted from the Cs2Te cathode are accelerated by a 1.6-cell L-band RF gun cavity operated at 60 MV/m maximum accelerating gradient at the cathode. Cylindrically shaped laser pulses with a flat-top temporal profile of about 20 ps FWHM and 2 ps rise and fall time are used to produce electron beams with extremely low emittance. The PITZ beam line was upgraded in 2010. The new gun cavity (prototype number 4.1) was installed January 2010. The new booster cavity (CDS) with well-defined field distribution was installed in July 2010. The diagnostic system for characterization of the laser hitting the photocathode was upgraded in October 2010. Emittance measurements results for different charges: 2 nC, 1 nC, 0.25 nC, 0.1 nC and 0.02 nC, will be presented. The optimization was done for different parameters, e.g. gun solenoid current, gun phase, laser spot size on the cathode, booster gradient.

THPC118	Present Status of Quantum Radiation Sources on the Basis of the S-band Compact Electron Linac	electron, radiation, cavity, linac	3164
	R. Kuroda, E. Miura, H. Toyokawa, K. Yamada, E. Yamaguchi AIST, Tsukuba, Ibaraki, Japan M. Kumaki RISE, Tokyo, Japan
	We have developed quantum radiation sources such as a laser Compton scattering (LCS) X-ray and a coherent THz radiation sources on the basis of the S-band compact electron linac at AIST in Japan. The S-band linac consists of the laser-driven photocathode rf gun and two 1.5 m-long acceleration tubes and can accelerate the electron beam up to about 42 MeV. The LCS X-ray source can generate a quasi-monochromatic hard X-ray with variable energy of 12 - 40 keV for medical and biological applications. Now, the multi-collision LCS system has been developed with the regenerative amplifier type laser storage cavity and the multi-bunch electron beam to increase the X-ray yield. On the other hand, the high-power coherent THz radiation source has been also developed and its peak power is estimated to be more than 1 kW in frequency range between 0.1 - 2 THz. The high-power THz radiation was applied to the scanning transmission imaging. Now, the high power THz time domain spectroscopy (TDS) has been developed for the material science. In this conference, we will report the present status of the S-band compact electron linac, our quantum radiation sources and applications.

THPC120	Experimental Investigation of Photocathode Thermal Emittance Components with a Copper Cathode*	emittance, cathode, gun, electron	3167
	H.J. Qian, Y.-C. Du, Hua, J.F. Hua, W.-H. Huang, C. Li, C.-X. Tang, L.X. Yan TUB, Beijing, People's Republic of China
	With progress of photocathode RF gun technology, thermal emittance has become the primary limitation of electron beam brightness. Extensive efforts have been devoted to study thermal emittance, but experiment results diverge between research groups and few can be well interpreted. One possibility is the undefined online cathode surface conditions, which may cause difference of work functions, field enhancement factor and surface roughness, and lead to thermal emittance divergence. In this paper, we report an experiment of characterizing online photocathode work function, field enhancement factor and surface roughness effect by measuring electric field dependence of photoemission quantum efficiency (QE) and thermal emittance in a Cu-cathode RF gun. Preliminary experiment results reveal huge thermal emittance contributed by surface roughness for the first time, and are in reasonable consistency with theoretical model prediction*. Ivan V. Bazarov et al., Phys. Rev. Lett. 10², 104801(2009) D.H. Dowell et al, Nucl. Instrum. Methods Phys. Res., Sect. A 622, 685 (2010). *D. Xinag et al, PAC’07, 10⁴⁹ (2007)

THPC126	RF Gun Studies for the SwissFEL Injector	gun, emittance, solenoid, cathode	3179
	A. Falone, A. Adelmann, J.-Y. Raguin, L. Stingelin PSI, Villigen, Switzerland
	The Paul Scherrer Institut (PSI) is planning a compact, high brightness hard X-ray free electron laser. For this purpose a new 2.5 cell RF gun has been designed at PSI and is now in production. The RF gun plays an important role in preserving beam emittance, and hence delivers a high quality beam to the injector. We present beam dynamic parametric studies on the effect of cell length variations using two different codes OPAL and ASTRA. Furthermore laser and other RF parameters are scanned to find the best working point of the injector. The simulations are showing that the SwissFEL injector requirements (ϵ<0.4 mm mrad normalized projected emittance) are achievable with a smooth dependence on the geometrical variation of the gun cell lengths confirming a robust RF design of the gun is possible.

THPC127	Recent Results from a Combined Diode-RF Gun	emittance, cathode, electron, gun	3182
	C.H. Gough, S. Ivkovic, M. Paraliev PSI, Villigen, Switzerland
	For the SwissFEL project, a novel combined diode-RF electron gun was tested at PSI, as a possible source for XFELs. Typically, electron bunches of 1-100 pC charge , 1-5 MeV energy and 2-0.3 um-rad emittance were produced and measured. The advantage of the combined gun is that diode geometry and emission surface can be changed readily. An optimum polishing procedure for magnesium photo cathodes was found, and various surfaces such as FEA's were tested in high gradient. Emittance changes for emission surface depression within the cathode, as well as laser spot size and anode hole size, were measured. Finally, the excellent performance of the gun permitted detailed study of the pepperpot EMSY (Emittance Measurement System) behaviour with changing beam parameters.

THPC129	Gallium Arsenide Photocathode Research at Daresbury Laboratory	cathode, electron, vacuum, gun	3185
	L.B. Jones, B.D. Fell, J.W. McKenzie, K.J. Middleman, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.J. Cash STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom N. Chanlek UMAN, Manchester, United Kingdom
	Significant effort has been expended over several years by ASTeC to optimise procedures for preparing GaAs photocathodes for use as high-current electron sources in accelerators. Having established robust chemical and thermal cleaning processes, and carried out lifetime studies on activated photocathodes by deliberately poisoning them, we present data showing high levels of Quantum Efficiency (QE) for heterostructure photocathodes when activated with Cs-O and Cs-NF3 procedures. We will show that the use of NF3 delivers higher QE, and conveys greater control in that the final QE level can be set more accurately using NF3 than with O. We plan to carry out further experiments on GaAs photocathodes to measure the 2-D energy distribution of the emitted electrons at both room and cryogenic temperatures. We are constructing a retarding-field electron calorimeter which will measure current as a function of retarding voltage. From this, we will establish the 2-D energy distribution in the electron beam, permitting a comparison of these figures for photocathodes at room and low temperatures. The goal is to create an ultra-bright electron source for use with particle accelerators. Proc IPAC ’10, TUPEC018, 1752-1754

THPC130	A 160 keV Photocathode Electron Gun Test Tacility	gun, electron, diagnostics, cathode	3188
	L.B. Jones, B.D. Fell, C. Hill, J.W. McKenzie, K.J. Middleman, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom R.J. Cash STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
	The ALICE ERL* at Daresbury Laboratory is a prototype 4th generation free-electron laser light source operating at IR wavelengths. An upgrade to the DC photoinjector gun has been designed and partially-constructed, but due to installation postponement, the system will be used for photocathode physics experiments. The re-designed gun will operate at 160 keV. The gun and photocathode preparation facility (PPF) will be assembled with a diagnostic beamline, supporting research towards high-brightness electron beams based on GaAs technology. Combining an external PPF with a load-lock facility allows the rapid exchange of photocathodes, thus permitting the testing of various different photocathode heterostructures, and fine control of the cleaning and activation processes applied during preparation. The diagnostics beamline will include a transverse kicker to study bunch length, and a dipole magnet for beam energy and energy spread measurements. Various horizontal and vertical slit and screen assemblies allow for emittance measurement, so providing full 6-D characterisation of the electron bunches generated. A current transformer and Faraday cups support bunch charge measurements. * Accelerators and Lasers In Combined Experiments electron Energy-Recovery Linac

THPC131	MAX-IV Linac Injector Simulations including Tolerance and Jitter Analysis	linac, gun, emittance, simulation	3191
	J.W. McKenzie, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom S. Thorin, S. Werin MAX-lab, Lund, Sweden
	The MAX-IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF) and an FEL (in phase 2). 100 pC bunches of electrons are created from a 1.5 cell S-band photocathode gun and subsequently accelerated up to 3 GeV by S-band linac sections. Simulations of the dynamics of the space-charge dominated beam up to 100 MeV are presented including an analysis of the tolerances required and the effects of jitter sources.

THPC132	A Velocity Bunching Scheme for Creating Sub-picosecond Electron Bunches from an RF Photocathode Gun	cavity, gun, emittance, solenoid	3194
	J.W. McKenzie, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Sub-picosecond electron bunches are in demand for various applications including Free Electron Lasers and electron diffraction experiments. Typically, for Free Electron Lasers, a multiple picosecond scale bunch is produced from a photoinjector with compression achieved via one or more magnetic chicanes by providing an appropriate energy chirp to the bunch in the preceding linac sections. This approach is complex, requiring many components, often including a higher harmonic linac section to linearise the longitudinal phase-space, and careful tuning in order to minimise emittance blow-up due to coherent synchrotron radiation. We present a scheme to deliver sub-picosecond electron bunches, based on a normal conducting RF gun and two short linac sections, one for providing velocity bunching and the second to capture the compressed bunch and accelerate to tens of MeV where the beam properties are then essentially frozen.

THPC134	LCLS RF Gun Copper Cathode Performance	cathode, gun, emittance, electron	3200
	A. Brachmann, F.-J. Decker, P. Emma, R.H. Iverson, P. Stefan, J.L. Turner, F. Zhou SLAC, Menlo Park, California, USA
	Funding: Work supported by Department of Energy contract DE-AC03-76SF00515 We report on the performance and the operational experience of the LCLS RF gun copper photocathodes used during the LCLS run I, II, III and IV. We discuss the problems of cathode surface contamination and our experience with methods to remove such contamination. Techniques to obtain high quantum efficiency (QE) while preserving the low emittance quality are discussed. Furthermore, we will present the current status of the installed cathode, its quantum efficiency and the typical injector emittances of the extracted beam.

THPC135	Optimal Parameters of the Photocathode Gun Space Charge to Improve Beam Quality	cathode, gun, electron, space-charge	3203
	M.G. Fedurin, C. Swinson, V. Yakimenko BNL, Upton, Long Island, New York, USA
	Accelerator Test Facility at Brookhaven National Laboratory operates with 5 MeV photocathode gun and 70 MeV linac for different range of experiments with a few picoseconds and a few micrometers emittance electron bunch. Many conducted experiments require beam with good spatial resolution and short length as well. NdYaG laser pulse turns to the electron bunch in the gun with space charge affecting on the own bunch length and transverse profile. Optimal beam loading parameters of the space charge in the photocathode RF gun could be found and used to improve bunch length and emittance. Simple model and experimental results on the Accelerator Test Facility at Brookhaven national Laboratory will be described

THPC136	High Efficiency Visible Photocathode Development	cathode, synchrotron, vacuum, diagnostics	3206
	J. Smedley, K. Mueller, T. Rao BNL, Upton, Long Island, New York, USA K. Attenkofer, S.W. Lee ANL, Argonne, USA I. Ben-Zvi, X. Liang, E.M. Muller, M. Ruiz-Oses Stony Brook University, Stony Brook, USA H.A. Padmore, T. Vecchione LBNL, Berkeley, California, USA
	Alkali antimonide cathodes are critical both for high average current photoinjectors for energy recovery linacs and for high quantum efficiency photodetectors. These cathodes have historically been plagued by extreme vacuum sensitivity, non-reproducibility and poor lifetime. We report on ongoing efforts to improve the performance of alkali antimonides (principally K2CsSb). Cathodes have been fabricated which have a QE of 7% at 532 nm. The films are much more resistant to oxygen and water exposure than previously thought, with a 50% yield lifetime of 20 hrs at 2 pBar partial pressure of water. Several analysis techniques have been employed in this study, including in-situ x-ray diffraction during growth to measure grain size and texture, measurement of transverse momentum distribution of the emitted electrons, and measurement of the stoichiometry of the films via x-ray fluorescence. An extensive study of the growth parameters, including both transparent and metallic substrates, sputtered and evaporated films, variation of growth time and temperatures and post-growth annealing processes, is currently underway.

THPC174	Manufacturing and Testing of the First Phase Shifter Prototypes Built by CIEMAT for the European-XFEL	controls, undulator, electron, free-electron-laser	3308
	I. Moya, J. Calero, J.M. Cela-Ruiz, L. García-Tabarés, A. Guirao, J.L. Gutiérrez, L.M. Martinez Fresno, T. Martínez de Alvaro, E. Molina Marinas, A.L. Pardillo, L. Sanchez, S. Sanz, F. Toral, C. Vazquez, J.G.S. de la Gama CIEMAT, Madrid, Spain
	Funding: Work partially supported by the Spanish Ministry of Science and Innovation under SEI Resolution on 17-September-2009. The European X-ray Free Electron Laser (EXFEL) will be based on a 10 to 17.5 GeV electron linac. Its beam will be used in three undulator systems to obtain ultra-brilliant X-ray flashes from 0.1 to 6 nanometres for experimentation. The undulator systems are formed by 5m long undulator segments and 1.1m long intersections in between. They accommodate a quadrupole on top of a precision mover, a beam position monitor, two air coil correctors and a phase shifter. The function of the phase shifter is to adjust the phase of the electron beam with respect to that of the radiation field when the wavelength is changed by tuning the gap. In this context, CIEMAT will deliver 92 phase shifters, as part of the Spanish in-kind contribution to the EXFEL project. This paper describes the engineering design, the manufacturing techniques and the mechanical and magnetic tests realized on the first prototypes.

THPO025	Longitudinal Beam Dynamics of a Laser Sliced Bunch	synchrotron, electron, radiation, damping	3397
	P. Kuske HZB, Berlin, Germany
	Nowadays fs-laser slicing of a bunch of electrons in storage rings is quite common for creating short VUV- and soft X-ray light pulses or pulses of coherently emitted THz-radiation over a couple of revolutions. In this paper the longitudinal dynamics of the sliced bunch is studied numerically. The calculations are based on the one dimensional solution of the Vlasov-Fokker-Planck-equation assuming that the shielded CSR-wake is dominating the dynamics of the 100 fs-long slice. It is found that the density modulation survives longer and that the CSR-spectra extend to higher frequencies at later turns even below the corresponding instability threshold. This very simple model seems to support experimental observations at the Swiss Light Source.

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MOYCA01

Status Report on the Commissioning of the Japanese XFEL at SPring-8

undulator, acceleration, electron, FEL

21

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

The Japanese XFEL at SPring-8, which was named SACLA (Spring-8 Angstrom Compact free electron LAser), was completed in FY2010. After RF full-power aging for about four months the beam commissioning of SACLA has been started since 21 February 2011. About one month later, in 23 March a design beam energy of 8 GeV was achieved and a spontaneous undulator radiation of 0.8 Angstrom was observed at the beam-line optical hutch by closing XFEL undulator gaps down to 5 mm in full-width. The beam commissioning has proceeded smoothly and since the middle of April we have entered to a tuning phase towards SASE lasing, which is at least one month ahead of schedule. This talk will report the beam commissioning overview of SACLA including SASE XFEL performance, key tuning-processes and critical issues for achieving the lasing.

Slides MOYCA01 [37.840 MB]

MOODA03

First Characterization of a Fully Superconducting RF Photoinjector Cavity

cavity, cathode, linac, solenoid

41

A. Neumann, W. Anders, R. Barday, A. Jankowiak, T. Kamps, J. Knobloch, O. Kugeler, A.N. Matveenko, T. Quast, J. Rudolph, S.G. Schubert, J. Völker
HZB, Berlin, Germany
P. Kneisel
JLAB, Newport News, Virginia, USA
R. Nietubyc
The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock, Poland
J.K. Sekutowicz
DESY, Hamburg, Germany
J. Smedley
BNL, Upton, Long Island, New York, USA
V. Volkov
BINP SB RAS, Novosibirsk, Russia
G. Weinberg
FHI, Berlin, Germany
I. Will
MBI, Berlin, Germany

As a first step towards a high brightness, high average current electron source for the BERLinPro ERL a fully superconducting photo-injector was developed by HZB in collaboration with JLab, DESY and the A. Soltan Institute. This cavity-injector ensemble is made up of a 1.6-cell superconducting cavity with a superconducting lead cathode deposited on the half-cell backwall. A superconducting solenoid is used for emittance compensation. This system, including a diagnostics beamline, has been installed in the HoBiCaT facility to serve as a testbed for beam dynamics studies and to test the combination SRF cavity and superconducting solenoid. This paper summarizes the characterization of the cavity in this configuration including Q measurements, dark current tests and field-stability analyses.

Slides MOODA03 [10.343 MB]

MOODB03

Capture and Transport of the Laser Accelerated Ion Beams for the LIGHT Project

proton, solenoid, simulation, ion

59

S.G. Yaramyshev, W.A. Barth, I. Hofmann, A. Orzhekhovskaya
GSI, Darmstadt, Germany
B. Zielbauer
HIJ, Jena, Germany

Funding: Work supported by EURATOM (IFK KiT Program) and HIC for FAIR
An impressive advantage of Laser Ion Sources is an extremely high beam brilliance. The LIGHT project (Laser Ion Generation, Handling and Transport) is dedicated to the production of protons (ions), accelerated up to 10 MeV by using the GSI PHELIX laser at GSI, and injected into a conventional accelerator. A successful experimental campaign stimulated further investigation of the focusing, transport and collimation of the high energy and high brilliance proton beam. In addition to the advanced codes, describing the very early expansion phase of the proton-electron cloud, the versatile multiparticle code DYNAMION was implemented to perform beam dynamics simulations for different possible transport lines. Potentially transport lines compraises magnetic quadrupole lenses and/or solenoids for transverse beam focusing. A bunch rotation rf cavity decreasing the energy spread of the protons was included into the simulations. The results of the beam dynamics simulations are presented, as well as benchmarking activities with other codes. Further developments of the experimental test stand and the different possibilities of its integration to the GSI accelerators chain are discussed.

Slides MOODB03 [2.185 MB]

MOPC014

RF Processing of L-band RF Gun for KEK-STF

cavity, gun, cathode, solenoid

92

M. Kuriki, H. Iijima, Y.M. Masumoto
HU/AdSM, Higashi-Hiroshima, Japan
H. Hayano, H. Sugiyama, J. Urakawa, K. Watanabe
KEK, Ibaraki, Japan
G. Isoyama, R. Kato
ISIR, Osaka, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
Y. Takahashi
Sokendai, Ibaraki, Japan

Funding: This work is supported by MEXT Quantum Beam Technology Program, KEK Promotion of collaborative research programs in universitie.
KEK STF (Superconducting Test Facility) is established for developing super-conducting accelerator technology for ILC (International Linear Collider). At KEK-STF, accelerator operation with a beam loading is planned in 2013. An electron injector based on L-band Photo-cathode RF gun is now being developed. A L-band RF gun designed by DESY and fabricated by FNAL has been placed in KEK-STF and RF processing was carried out. The results of the RF processing and status of STF injector will be presented.

MOPC028

Beam Acceleration of DPIS RFQ at IMP

rfq, ion, ion-source, target

128

Z.L. Zhang, X.H. Guo, Y. He, Y. Liu, S. Sha, A. Shi, L.P. Sun, H.W. Zhao
IMP, Lanzhou, People's Republic of China
R.A. Jameson, A. Schempp
IAP, Frankfurt am Main, Germany
M. Okamura
BNL, Upton, Long Island, New York, USA

Beam test of the direct plasma injection scheme (DPIS) is carried out successfully for the first time in China, by setting up a comprehensive test and research platform of RFQ and laser ion source. The C⁶⁺ beam is accelerated successfully, and the peak beam current reaches more than 6mA which is measured by a Faraday cup of unique structure. The RF power coupled into the RFQ cavity is also examined, and results reveal that it is the RF power of about 195kW that can produce the peak beam current.

MOPC060

Bunching-frequency Multiplication for a THz Pulse-train Photoinjector

electron, bunching, linac, acceleration

220

Y.-C. Huang, F.H. Chao, C.H. Chen, K.Y. Huang
NTHU, Hsinchu, Taiwan

Funding: This work is supported by National Science Council under Contract NSC 99-2112-M-007 -013 -MY3.
A THz-pulse-train photoinjector* employs a THz-pulse-train laser as its driver laser to generate a beam with a bunching frequency in the THz range. However a laser frequency is on the order of a few hundred THz. It is not possible to generate a beam from the pulse-train photoinjector with a bunching frequency exceeding the laser’s carrier frequency. In view of the strong demand for a compact x-ray free-electron laser (FEL), it is highly desirable to multiply the bunching frequency of the beam from a pulse-train injector to the x-ray frequencies. We propose to chirp the energy of the THz electron pulse train in an accelerator and compress the whole beam in a magnet to increase the electron bunching frequency. Our study shows a compression ratio or a bunching-frequency multiplication factor of a few tens is achievable from a properly designed magnetic chicane compressor. The bunching factor, however, is unfortunately degraded due to the energy chirp, emittance growth, and wake-field generation. In the conference, we will show that a bunching factor of a few ppm in the bunch-frequency multiplied beam is sufficient to build up the FEL power from a 10-time length reduced undulator.
* Y. C. Huang, “Laser-beat-wave bunched beam for compact superradiance sources,” International Journal of Modern Physics B, Vol. 21 Issue 3/4, p277-286 (2007).

MOPC067

X-Band Test Station at Lawrence Livermore National Laboratory

electron, klystron, cathode, brightness

235

R.A. Marsh, F. Albert, S.G. Anderson, C.P.J. Barty, G.K. Beer, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, T.L. Houck
LLNL, Livermore, California, USA
C. Adolphsen, A.E. Candel, T.S. Chu, E.N. Jongewaard, Z. Li, C. Limborg-Deprey, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou
SLAC, Menlo Park, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
An X-band multi-bunch test station is being built at LLNL to investigate the science and technology paths required to boost the current mono-energetic gamma-ray (MEGa-Ray) brightness by orders of magnitude. The test station will consist of a 5.5 cell X-band RF photoinjector, single accelerator section, and beam diagnostics. Beam quality must be exceedingly high in order to produce narrow-bandwidth gamma-rays, requiring a robust state of the art photoinjector. The photoinjector will be a high gradient (200 MV/m peak surface field on the cathode) standing wave structure, featuring a dual feed racetrack coupler, elliptical irises, and an optimized first cell length. A solid-state Scandinova modulator will power a single SLAC XL4 11.424 GHz 50 MW klystron. RF distribution will allow for full powering of the photoinjector with the balance of the RF powering a single accelerator section so that the electron parameters can be measured. The status of the facility will be presented including commissioning schedule and first experiment plans. Future experimental programs pertinent to Compton scattering R&D, high gradient structure testing, and light source development will be discussed.

MOPC081

Pulsed Mode Operation and Longitudinal Parameter Measurement of the Rossendorf SRF Gun

gun, cavity, SRF, cathode

262

J. Teichert, A. Arnold, H. Büttig, M. Justus, U. Lehnert, P. Michel, P. Murcek, Ch. Schneider, R. Schurig, R. Xiang
HZDR, Dresden, Germany
T. Kamps, J. Rudolph, M. Schenk
HZB, Berlin, Germany
I. Will
MBI, Berlin, Germany

Funding: The European Community-Research Infrastructure Activity under the FP7 program (EuCARD, contract number 227579) the German Federal Ministry of Education and Research grant 05 ES4BR1/8.
The Rossendorf SRF gun with a 3 1/2 cell cavity has been operated since 2007. It has produced CW beam with the electron energy of 3 MeV and the average current up to 16 μA. The electron beam of the gun has successfully injected the ELBE superconducting linac since 2010. The Nb cavity has shown constant quality during the operation and for the Cs2Te photocathode life time of months could be obtained. Recently the gun started to run in the pulsed mode with higher gradient. The longitudinal parameters have been measured in this mode. The dark current arose from the high gradient is studied. The main field emission source has been found to be the half cell. Meanwhile, two modified 3+1/2 cell niobium cavities have been fabricated and tested in Jlab. In this paper the new status of the SRF gun will be presented, and the latest results of the beam experiments will be discussed.

MOPC145

Recent Progress on the Technical Realization of the Bunch Phase Timing System BuTiS

controls, cavity, diagnostics, status

418

B. Zipfel, P. Moritz
GSI, Darmstadt, Germany

A high precision phase synchronous clock distribution system is mandatory for generating local RF reference signals in an accelerator complex. The dedicated Bunch Timing System (BuTiS) at GSI performs this function. The accuracy of the realized installation under rough ambient conditions is presented. Procedures for calibration and standardization aspects of system modules are pointed out. Hardware as well as software interfaces of the system are described. The interfacing between GPS and BuTiS are explained.

MOPC146

Development of Timing Distribution System with Femto-second Stability

feedback, linac, controls, acceleration

421

T. Naito, K. Ebihara, S. Nozawa, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
M. Amemiya
AIST, Tsukuba, Japan

A timing distribution system with femto-second stability has been developed for the RF synchronization of accelerator and the laser synchronization of the pump-probe experiments. The system uses a phase stabilized optical fiber(PSOF) and an active fiber length stabilization. The PSOF has 5 ps/km/degC of the temperature coefficient. The active fiber length stabilization uses the phase detection of the round-trip sinusoidal wave and the fiber stretcher for the compensation of the fiber length. In this paper, we present the test results on a 500 m long signal distribution. The preliminary results of the timing stability are 20 fs at several minutes and 100 fs at four days, respectively.

MOPC148

Optical Clock Distribution System at the ALICE Energy Recovery Linac

pick-up, electron, FEL, feedback

427

T.T. Ng, S.P. Jamison
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Highly stable clock distribution across future light sources is important for the synchronisation of beam generation, manipulation and diagnostics with photon experiments. Optical fibre technology can be used to combat the stability challenges in distributing clock signals over long distances with coaxial cable. We report here on the status of the optical clock distribution system installed on the ALICE energy recovery linac which uses the propagation of ultra-short optical pulses to carry the clock signal. We also present the characterisation of a beam arrival monitor suitable using <40 pC bunch charges and 7 mW, sub-100 fs distributed clock pulses.

MOPC150

High Charge PHIN Photo Injector at CERN with Fast Phase Switching within the Bunch Train for Beam Combination

cathode, vacuum, gun, bunching

430

M. Divall Csatari, A. Andersson, B. Bolzon, E. Bravin, E. Chevallay, A.E. Dabrowski, S. Döbert, V. Fedosseev, C. Heßler, T. Lefèvre, S. Livesley, R. Losito, O. Mete, M. Olvegård, M. Petrarca, A. Rabiller
CERN, Geneva, Switzerland
A. Drozdy
BUTE, Budapest, Hungary
D. Egger
EPFL, Lausanne, Switzerland

The high charge PHIN photo-injector was developed within the frame of the European CARE program to provide an alternative to the drive beam thermionic gun in CTF3 (CLIC Test Facility) at CERN. In PHIN 1908 bunches are delivered with bunch spacing of 1.5 GHz and 2.33 nC charge per bunch. Furthermore the drive beam generated by CTF3 requires several fast 180 deg phase-shifts with respect to the 1.5 GHz bunch repetition frequency in order to allow the beam combination scheme developed at CTF3. A total of 8 sub-trains, each 140 ns long and shifted in phase with respect to each other, have to be produced with very high phase and amplitude stability. A novel fiber modulator based phase-switching technique developed on the laser system provides this phase-shift between two consecutive pulses much faster and cleaner than the base line scheme, where a thermionic electron gun and sub-harmonic bunching are used. The paper describes the fiber-based switching system and the measurements verifying the scheme. Stability measurements are presented for the phase-coded system. The paper also discusses the latest 8nC charge production and cathode life-time studies on Cs2Te.

MOPC154

RF Photo Gun Stability Measurement at PITZ

gun, feedback, cavity, electron

442

I.I. Isaev, H.-J. Grabosch, M. Gross, L. Hakobyan, Ye. Ivanisenko, G. Klemz, W. Köhler, M. Krasilnikov, M. Mahgoub, D. Malyutin, A. Oppelt, M. Otevřel, B. Petrosyan, S. Rimjaem, F. Stephan, G. Vashchenko, S. Weidinger, R.W. Wenndorff
DESY Zeuthen, Zeuthen, Germany
G. Asova
INRNE, Sofia, Bulgaria
M. Hoffmann, H. Schlarb
DESY, Hamburg, Germany
M.A. Khojoyan
YerPhI, Yerevan, Armenia
D. Richter
HZB, Berlin, Germany
A. Shapovalov
NRNU MEPHI, Moscow, Russia
I.H. Templin, I. Will
MBI, Berlin, Germany

The stability of the RF phase in the RF photo injector gun is one of the most important factors for the successful operation of linac based free-electron lasers. Instabilities in the RF launch phase can significantly reduce the beam quality. Investigation on the dependence of different gun parameters and selection of optimal conditions are required to achieve high RF gun phase stability. The phase stability of the RF field is measured using the phase scan technique. Measurements were performed for different operating conditions at the Photo Injector Test facility at DESY, location Zeuthen (PITZ). Obtained stability measurement results will be presented and discussed.

MOPO018

Active Beam Current Stabilization in the Cornell ERL Prototype Injector

feedback, gun, cavity, cathode

523

F. Löhl, P. Szypryt
CLASSE, Ithaca, New York, USA

In order to operate the Cornell ERL prototype injector at beam currents beyond 10 mA, the beam current has to be highly stable. The reason is that fast beam current fluctuations generate transient effects in the DC gun voltage as well as in the fields of subsequent superconducting cavities, which can lead to excessive beam loss or to trips of subsystems. Therefore, a feedback scheme was developed which uses the signal of a beam current monitor as an input, and applies appropriate corrections to a Pockels cell installed within the laser path of the photo-injector laser. In this paper, high current results achieved with this feedback scheme are presented.

MOPO023

Laser-based Alignment System at the KEKB Injector Linac

alignment, linac, vacuum, injection

529

M. Satoh, N. Iida, T. Suwada
KEK, Ibaraki, Japan
K. Minoshima, S. Telada
AIST, Tsukuba, Japan

A laser-based alignment system is under development at the 500-m-long KEKB injector linac. The original system was designed and constructed more than thirty-years ago, and thus, we are revisiting our alignment system because the previous alignment system has become too obsolete. The new alignment system is again strongly required for the next generation SuperKEKB project. The new laser alignment system is similar to the previous one, which comprises a helium-neon laser and quadrant photodetectors installed in vacuum light pipes. A girder displacement of the accelerating structure can be precisely measured in the direction of the laser-ray trace, where the laser light must stably propagate up to 500-m downstream without any orbital and beam-size fluctuation. We tested the laser-ray propagation and the stability along a 100-m-long beam line under a vacuum condition of 0.1-1 Torr. In this paper, we will report the system description and test results in detail.

MOPO025

Experimental Study on New Laser-based Alignment System utilizing a Sequential Three-point Method at the KEKB Injector Linac

alignment, linac, focusing, factory

532

T. Suwada, M. Satoh
KEK, Ibaraki, Japan
K. Minoshima, S. Terada
AIST, Tsukuba, Japan

A new laser-based alignment system is under development in order to precisely align accelerator components along an ideal straight line at the 600-m-long KEKB injector linac. A well-known sequential three-point method with Fresnel lenses and a CCD camera is revisited in a preliminary design of the new alignment system. The new alignment system is strongly required in order to stably accelerate high-brightness electron and positron beams with high bunch charges and also to keep the beam stability with higher quality towards the Super B-factory at KEK. A new laser optics has been developed and the laser propagation characteristics has been systematically investigated at a 200-m-long straight section at atmospheric pressure. In this report, the preliminary experimental results are reported along with the basic design of the new laser-based alignment system.

MOPO031

Alignment of theTPS Front-End Prototype

alignment, synchrotron, survey, synchrotron-radiation

550

C.K. Kuan, Y.T. Cheng, W.Y. Lai, I.C. Sheng, T.C. Tseng, H.Y. Yan
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

The Taiwan Photon Source (TPS) is a 3-GeV third-generation source of synchrotron radiation with beam current 500 mA stored in the storage ring. A front end allows intense synchrotron light generated in the storage ring to pass through to a beamline. Most heat load of the synchrotron light is removed in the front ends to protect the beamline components. Alignment of front-end components becomes important to prevent damage from the large heat load. Because of the many front ends and the brief period of installation, the alignment work should be easy, quick and reliable. Using a shim method, the adjustable degrees of freedom are decreased from six to two. This adjustment work becomes easier and quicker. The alignment of a front-end prototype is described here.

MOPO033

Design and Development of a Laser Positioning System for TPS Magnets Alignment Inspection during the Installation on a Girder

quadrupole, sextupole, alignment, lattice

556

Chen, M. L. Chen, H.C. Ho, K.H. Hsu, W.Y. Lai, S.Y. Perng, Y.L. Tsai, T.C. Tseng, H.S. Wang
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

A novel optical inspection architecture is designed and developed for positioning the TPS (Taiwan Photon Source) quadrupole and sextupole magnets on the girder within 30 um. This positioning system is a laser-based scheme consists of two laser position sensing devices (PSD) and two granite blocks as the standard reference of magnets. The laser position sensing device (PSD) is mounted on an adjustable circular steel module and the module is installed in a granite block. With the PSD position being adjusted and corrected, the PSD module center can be identical to the ideal pole position of magnets on the girder within 10um. The Laser ray is also adjusted and aligned according to the ideal reference line of magnets. Finally the granite blocks are replaced with the quadrupole and sextupole magnets at installation, the assembling error of magnets can be detected from the PSD module. This paper describes the detail of the system development and testing results.

MOPO034

From Survey Alignment toward Auto-alignment for the Installation of the TPS Storage Ring Girder System

survey, alignment, photon, controls

559

T.C. Tseng, Chen, M. L. Chen, H.C. Ho, K.H. Hsu, W.Y. Lai, C.J. Lin, H.M. Luo, S.Y. Perng, P.L. Sung, Y.L. Tsai, H.S. Wang
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

The TPS (Taiwan Photon Source) project is now under civil construction. The whole building is constructed half underground and 12m deep compared to the TLS due to the stability consideration, so the survey and alignment works are quite confined and difficult. For positioning the magnets precisely and quickly, a high accuracy auto-tuning girders system combined with survey network procedures were established to accomplish the installation tasks. The position data from the survey network will define a basis for the motorized girder system to auto-tune and improve the accuracy. A mockup of one twenty-fourth section (one cell) had been installed at NSRRC for interface examination and further testing. In this paper, the procedures from the traditional survey network to auto-aliment system design and algorithm are described. Meanwhile, a preliminary testing result is also included.

MOPO037

Concept of Femtosecond Timing and Synchronization Scheme at ELBE

electron, controls, status, pick-up

565

M. Kuntzsch, A. Büchner, M. Gensch, A. Jochmann, T. Kirschke, U. Lehnert, F. Röser
HZDR, Dresden, Germany
M.K. Bock, M. Bousonville, M. Felber, T. Lamb, H. Schlarb, S. Schulz
DESY, Hamburg, Germany

The Radiation Source ELBE at Helmholtz-Zentrum Dresden-Rossendorf is undergoing an extension to offer capacity for various applications. The extension includes the setup of a THz-beamline with a dedicated laboratory and a beamline for electron-beam - high-power laser interaction. The current synchronization scheme offers stability on the picoseconds level. For pump-probe experiments using optical lasers, the desired synchronization between the pump and the probe pulse should be on the femtosecond scale. In the future there will be an optical synchronization system with a pulsed fiber laser as an optical reference. The laser pulses will be distributed over stabilized fiber links to the remote stations. It is planned to install EOM-based beam arrival time monitors (BAMs) in order to monitor the bunch jitter and to establish a beam-based feedback to reduce the jitter. Besides that, the timing system has to be revised to generate triggers for experiments with low repetition rate, two electron guns (thermionic DC, superconducting RF) and several lasers. The Poster will show the possible layout of the future Timing and Synchronization System at ELBE.

MOPO040

RF Reference Distribution for the Taiwan Photon Source

synchrotron, controls, diagnostics, LLRF

571

K.H. Hu, Y.-T. Chang, J. Chen, Y.-S. Cheng, P.C. Chiu, K.T. Hsu, S.Y. Hsu, C.H. Kuo, D. Lee, C.-Y. Liao, C.Y. Wu
NSRRC, Hsinchu, Taiwan

Taiwan Photon Source (TPS) is a low-emittance 3-GeV synchrotron light source with circumference of 518.4 m which is being under construction at National Synchrotron Radiation Research Center (NSRRC) campus. Low noise 500 MHz master oscillator and novel fiber based CW RF reference distribution system will be employed to take advantages of advanced technology in this field and deliver better performance. The preliminary test of the prototype system is summarized in this report.

MOPO042

Photonic Crystal Fibre Laser for Electron Beam Emittance Measurement*

emittance, electron, diagnostics, extraction

577

L. Corner, L.J. Nevay, R. Walczak
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

We discuss the recent progress in the development of a high repetition rate, high energy fibre laser for intratrain laser-wire scans of transverse electron beam sizes. A commercial fibre laser (1uJ, 6.49MHz) is amplified in rod type photonic crystal fibre using a burst mode format, which has the advantage of allowing us to exploit very high transient gain while reducing the heat load deposited in the amplifier. The amplified pulses are over 180uJ spaced at 154ns, suitable for intratrain scanning at the ATF2. The spatial beam quality is excellent (M2 = 1.07), indicating that it will be possible to focus the laser to a spot size of ~ λ, enabling us to reach high intensities. The amplified pulse duration is 200ps, which can be compressed to less than the electron bunch length to increase the laser-wire signal to noise ratio. The performance of the laser system is analysed with respect to the demands of the laser-wire experiment.

MOPO043

Applications of Lasers to Accelerator Physics at SSRL

gun, cathode, photon, electron

580

D.L. Robinson
Cal Poly, San Luis Obispo, California, USA
W.J. Corbett
SLAC, Menlo Park, California, USA

Recent advances in accelerator physics and SR research have generated the need for high-power lasers in the SPEAR3 accelerator complex. On the injector side, two lasers are being used to test different photocathode materials and to provide photo-assisted emission from the standard dispenser cathode RF gun. For the storage ring, both a TiSa oscillator and a fiber laser locked to the RF master oscillator have been used to characterize short-pulse electron bunches in cross-correlation experiments. These lasers are also used in SR experiments for pump-probe characterization of materials. In this paper we review the laser-based systems, preliminary results and outlook for the future.

MOPO044

Bunch Length Measurements in Low-Alpha Mode at SPEAR3 with First Time-Resolved Pump/Probe Experiments*

photon, synchrotron, single-bunch, radiation

583

J.S. Wittenberg, A. Lindenberg, A. Miller
Stanford University, Stanford, California, USA
W.J. Corbett, L. Wang
SLAC, Menlo Park, California, USA

Funding: Work sponsored by U.S. Department of Energy Contract DE-AC03-76SF00515, Office of Basic Energy Sciences and SLAC Laboratory Directed Research Development funds (LDRD)
The SPEAR3 synchrotron light source can be operated in low-alpha mode to generate x-ray pulse durations of order 1ps, well below streak camera resolution limits yet accessible by laser/sr cross-correlation measurements. Initial CC tests performed with a 50fs TiSa laser, frequency doubling BBO, photodiode and lock-in amplifier resolved bunch lengths down to about 6ps rms with 85uA single-bunch current. By reconfiguring the experimental setup to utilize a fiber laser, sum frequency generation and single photon counter it is now possible to measure profiles in the 1ps rms range with only 5uA single-bunch current. In this paper we report on the most recent measurements, simulations, modeling efforts and prospects for further improvement.

TUZA01

Commissioning and Initial Operation of FERMI@Elettra

FEL, electron, photon, undulator

918

S. Di Mitri, E. Allaria, R. Appio, L. Badano, S. Bassanese, F. Bencivenga, A.O. Borga, M. Bossi, E. Busetto, C. Callegari, F. Capotondi, K. Casarin, D. Castronovo, P. Cinquegrana, D. Cocco, M. Cornacchia, P. Craievich, R. Cucini, I. Cudin, G. D'Auria, M.B. Danailov, R. De Monte, P. Delgiusto, A.A. Demidovich, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, S. Ferry, V. Feyer, L. Fröhlich, P. Furlan Radivo, G. Gaio, F. Gelmetti, L. Giannessi, R. Gobessi, R. Ivanov, E. Karantzoulis, M. Kiskinova, M. Lonza, A.A. Lutman, C. Masciovecchio, R.H. Menk, M.M. Milloch, M.M. Musardo, I. Nikolov, S. Noe, F. Parmigiani, L. Pavlovič, E. Pedersoli, G. Penco, M. Petronio, M. Predonzani, E. Principi, E. Quai, G. Quondam, F. Rossi, L. Rumiz, C. Scafuri, C. Serpico, P. Sigalotti, C. Spezzani, M. Svandrlik, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, D. Wang, M. Zaccaria, D. Zangrando
ELETTRA, Basovizza, Italy
M. Alagia, A. Kivimaki, M. Zangrando, M. de Simone
IOM-CNR, Trieste, Italy
L. Avaldi, P. Bolognesi, M. Coreno, P. O’Keeffe
CNR - IMIP, Trieste, Italy
M. Dal Forno
DIEIT, Trieste, Italy
G. De Ninno, S. Spampinati
University of Nova Gorica, Nova Gorica, Slovenia
M. Devetta, T. Mazza, P. Piseri
Università degli Studi di Milano, Milano, Italy
E. Ferrari
Università degli Studi di Trieste, Trieste, Italy
S. Stranges
Università di Roma "La Sapienza", Roma, Italy

Funding: Work was supported in part by the Italian Ministry of University and Research under grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3.
This article describes the design goals of FERMI@Elettra, reports on the goals achieved so far and shows how the facility development has been driven by the new research frontier of ultra-fast, extreme ultra-violet and soft X-ray science. The commissioning phases and first experience with user pilot experiments are presented and discussed.

Slides TUZA01 [13.401 MB]

TUZA02

sFLASH - Present Status and Commissioning Results

undulator, electron, FEL, radiation

923

V. Miltchev, S. Ackermann, A. Azima, J. Bödewadt, F. Curbis, M. Drescher, E. Hass, Th. Maltezopoulos, M. Mittenzwey, J. Rönsch-Schulenburg, J. Roßbach, R. Tarkeshian
Uni HH, Hamburg, Germany
H. Delsim-Hashemi, K. Honkavaara, T. Laarmann, H. Schlarb, S. Schreiber, M. Tischer
DESY, Hamburg, Germany
R. Ischebeck
PSI, Villigen, Switzerland
S. Khan
DELTA, Dortmund, Germany

The free-electron laser in Hamburg (FLASH) was previously being operated in the self-amplified spontaneous emission (SASE) mode, producing photons in the XUV wavelength range. Due to the start-up from noise the SASE-radiation consists of a number of uncorrelated modes, which results in a reduced coherence. One option to simultaneously improve both the coherence and the synchronisation between the FEL-pulse and an external laser is to operate FLASH as an amplifier of a seed produced using high harmonics generation (HHG). An experimental set-up - sFLASH, has been installed to test this concept for the wavelengths below 40 nm. The sFLASH installation took place during the planed FLASH shutdown in the winter of 2009/2010. The technical commissioning, which began in the spring of 2010, has been followed by seeded-FEL commissioning, FEL-characterisation and pilot experiments. In this contribution the present status and the sFLASH commissioning results will be discussed.

Slides TUZA02 [4.125 MB]

TUPC009

The Recent JINR Advances in Technology Development on Linear Accelerators

electron, radiation, FEL, cryomodule

1006

G. Shirkov, N. Balalykin, A. Dudarev, E. Syresin, G.V. Trubnikov, Yu.A. Yulian
JINR, Dubna, Moscow Region, Russia
E. Khazanov
IAP/RAS, Nizhny Novgorod, Russia

JINR experts take part in a few ILC related projects including photo injector prototype, participation in design and construction of cryomodules, RND on design of a new version of superconducting niobium resonator, laser metrology, etc. Some new results of this activity as well as recent data of ILC siting investigations in the Dubna region are presented.

TUPC010

Status of the Manufacturing of Accelerating Structures for LINACs

linac, vacuum, controls, extraction

1009

F.M. Mirapeix, J. Añel, J. Castillo, A. Ortiz
HTS, Mendaro, Spain
X. Aldalur, J. Amores, A. Urzainki
DMP, Mendaro, Spain

Funding: HTS, DMP, ZEHATZ, CERN
Particle accelerators need ongoing development in the state of the art of the field: high-quality manufacturing of accelerating structures, PETS, but also drift tubes, bunchers, high-power couplers, alignment systems, precision test stands, etc. They also require engineering projects in the range of mechatronics, thermodynamics, microwaves, ultra high vacuum, cryogenics, joining techniques, high precision manufacturing, 3D high precision scanning, etc. HTS together with DMP are actually working on all this fronts. In this paper, the actual status of the manufacturing capabilities concerning some accelerating structures will be described.

TUPC031

Advanced Research Electron Accelerator Laboratory Based on Photocathode RF Gun

gun, electron, emittance, controls

1066

B. Grigoryan, G.A. Amatuni, V.S. Avagyan, A. Grigoryan, M. Ivanyan, V.G. Khachatryan, E.M. Laziev, K. Manukyan, I.N. Margaryan, V. Sahakyan, A. Sargsyan, A. Tarloyan, A.V. Tsakanian, V.M. Tsakanov, A. Vardanyan
CANDLE, Yerevan, Armenia
T. Vardanyan
YSU, Yerevan, Armenia

The low energy sub-picosecond duration electron bunches with extremely small beam emittance have wide applications in advanced research of new accelerator concepts, radiation physics, time-resolved pulse radiolysis and electron diffraction. The conceptual design and experimental program of the Advanced Research Electron Accelerator Laboratory (AREAL) at CANDLE based on photocathode RF gun are presented. The AREAL design implies single and multibunch operation modes with variable beam energy of 5-20 MeV and 10-100 pC bunch charge. The design is based on 3 GHz 1.6 cells RF gun followed by S-Band accelerating linac.

TUPC043

SEM Field Emission Probe Surface Science Study

cathode, vacuum, electron, gun

1096

L. Laurent, R.E. Kirby, S.G. Tantawi
SLAC, Menlo Park, California, USA

Funding: This work is supported by Department of Energy Contract No. DE-AC03- 76SF00515.
After decades of rf breakdown research, a common acknowledgement among researchers is that a better understanding of what is happening on the surface at a microscopic level needs to be the impetus for future studies. We are designing and fabricating an electron microscope-based high-electric-field current-emission probe to study topographic material features which will enable us to better understand and further advance the technology of high-brightness photocathode rf guns and enable the study of high gradient phenomena. The SEM field emission probe will provide an important diagnostic tool allowing cathodes and high gradient surfaces to be evaluated before and after testing and will help identify and understand the relationship between high field emission locations and vacuum breakdown, non-uniform emission, surface cracking, hotspots, etc. The preliminary results and 2012 goals will be presented.

TUPC057

Femtosecond Photoinjector and Relativistic Electron Microscopy

gun, electron, emittance, cathode

1126

J. Yang, K. Kan, Y. Murooka, N. Naruse, K. Tanimura, Y. Yoshida
ISIR, Osaka, Japan
J. Urakawa
KEK, Ibaraki, Japan

A new rf gun driven by a femtosecond laser has been developed successfully for the relativistic electron diffraction in Osaka University for the study of ultrafast dynamics of intricate molecular and atomic processes in materials. The beam dynamics of femtosecond electron bunch in the rf gun were investigated to achieve a low-emittance and low-energy-spread; i.e. 0.1 mm-mrad and 10^-4. A time-resolved relativistic electron microscopy is being developed to reveal the hidden dynamics on the femtosecond and nanometer scales. The same demonstrations of the MeV electron diffraction/imaging measurements were reported.

TUPC058

Design of a Chirping Cell Attached RF Gun for Ultrashort Electron Generation

gun, electron, cavity, radiation

1129

K. Sakaue, K. Tamai, M. Washio
RISE, Tokyo, Japan
J. Urakawa
KEK, Ibaraki, Japan

Funding: Work supported by JSPS Grant-in-Aid for Scientific Research (A) 10001690
We have been developing an S-band photocathode rf electron gun at Waseda university. Our rf-gun cavity was firstly designed by BNL and then, modified by our group. In this paper, we will introduce a newly designed rf-gun cavity with energy chirping cell. To generate an energy chirped electron bunch, we attached extra-cell for 1.6cell rf-gun cavity. Cavity design was done by Superfish and particle tracing by PARMELA. By optimizing the chirping cell, we observed linear chirped electron bunch. The front electron have lower energy than rear. Then transporting about 2m, the bunch can be compressed down to 200fsec electron bunch with the charge of 160pC. This ultrashort bunch will be able to use for generating CSR THz radiation, pumping some material to be studied by pulse radiolysis method, and so on. In this conference, the design of chirping cell attached rf-gun, the results of tracing simulation and plan of manufacturing will be presented.

TUPC059

Study on Energy Compensation by RF Amplitude Modulation for High Intense Electron Beam Generated by a Photocathode RF-Gun

beam-loading, electron, cavity, gun

1132

Y. Yokoyama, T. Aoki, K. Sakaue, T. Suzuki, M. Washio, T. Yamamoto
RISE, Tokyo, Japan
H. Hayano, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
R. Kuroda
AIST, Tsukuba, Ibaraki, Japan

Funding: Work supported by JSPS Grant-in-Aid for Scientific Research(A)10001690 and JST Quantum Beam Program.
At Waseda University, we have been studying a high quality electron beam generation and its application experiments with a Cs-Te photocathode RF-Gun. To generate more intense and stable electron beam, we have been developing the cathode irradiating UV laser which consists of optical fiber amplifier and LD pumped amplifier. As the result, more than 100 multi-bunch electron beam with 1nC each bunch charge was obtained. However, it is considered that the accelerating voltage will decrease because of the beam loading effect. So we have studied the RF amplitude modulation technique to compensate the beam energy difference. The energy difference will caused by transient accelerating voltage in RF-Gun cavity and beam loading effect. As the result of this compensation method, the energy difference has been compensated to 1%p-p, while 5%p-p without compensation. In this conference, we will report the details of energy compensation method using the RF amplitude modulation, the results of beam experiments and the future plans.

TUPC065

Upgrade of the ISAC Time-of-flight System

ion, ISAC, alignment, diagnostics

1147

V.A. Verzilov, J. Lassen, R.E. Laxdal, M. Marchetto
TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada

The ISAC facility at TRIUMF produces stable and radioactive ion beams in a wide range of intensities and energies. The beam diagnostics was designed to support the beam delivery in every possible operating regime. Thus, the time-of-flight system is capable of measuring the beam velocity with accuracy of better than 0.1% at beam intensities from 10¹1 down to ~ 10⁴ ions per second. It consists of three high resolution timing secondary electron emission monitors and has been in operation since 2006. Recently all three monitors were rebuilt with the aim to facilitate monitor alignment with respect to the beam. The system was also equipped with an UV laser that allows perform an accurate absolute calibration and monitor tuning with no beam present.

TUPC066

Charged Particle Beam Profile Detector based on Yb-doped Optical Fibers

radiation, proton, ion, linac

1150

C.S. Søndergaard
Aarhus University Hospital, Aarhus, Denmark
A. Baurichter, B.R. Nielsen
Danfysik A/S, Jyllinge, Denmark
G. Boudreault
Rigshospitalet Copenhagen, PET and Cyclotron Unit, Copenhagen, Denmark
K. Hansen, D.V. Madsen, J. Rasmussen, B.F. Skipper
Aarhus School of Engineering, Aarhus, Denmark
M. Kristensen
Aarhus University, Aarhus, Denmark
S.P. Møller
ISA, Aarhus, Denmark
A. Peters
HIT, Heidelberg, Germany

Funding: The Danish National Advanced Technology Foundation, contract # 002-2005-1
A radiation robust, high dynamic range beam profile detector based on scintillating fibers will be presented. The beam profile detector has been developed for particle therapy type ion beams of multiple hundreds MeV/n in the intensity range from 10⁵ to 10⁹ ions/s as a simple and less expensive replacement for MWPC based detectors. Scintillating fibers are typically based on doped polymers, which are sensitive to radiation damage. Here we report on the advantage of using silica optical fibers doped with rare-earth elements for the purpose of detecting ionizing radiation. Specifically, we find that ytterbium doped fibers generate a strong emission signal in the near-infrared from the Yb³⁺ state when penetrated by ionizing radiation, and that the emission has a high resistance against the accumulated dose in the fiber. We demonstrate the use of such fibers in a beam profile detector for charged particle beams in medical applications (radionuclide production and hadron therapy); more generally they are a promising alternative for prolonged used in ionizing radiation, such as accelerator diagnostics equipment or space applications.

TUPC074

A New Counting Silicon Strip Detector System for Precise Compton Polarimetry

electron, polarization, photon, scattering

1171

R. Zimmermann, W. Hillert, J.C. Wittschen
ELSA, Bonn, Germany

Funding: Supported by the German Research Foundation within the SFB/TR16
A Compton polarimeter is currently being installed at the Electron Stretcher Facility ELSA to monitor the degree of polarization of the stored electron beam. For this purpose, circularly polarized light that is emitted by a laser and backscattered off the beam has to be detected. Above all, as a result of ELSA's beam energies, it is necessary to measure the shift of the center of the photon spatial distribution which is obtained when the polarization of the laser is switched from left-hand to right-hand circular polarization with an accuracy of a few microns. In order to meet the required specifications, a new counting silicon strip detector system has been developed in cooperation with the SiLab/ATLAS group of the Physics Institute of the University of Bonn. In this contribution, the design of the system will be presented and first results will be shown.

TUPC076

Realization of a High Bandwidth Bunch Arrival-time Monitor with Cone-shaped Pickup Electrodes for FLASH and XFEL

pick-up, electron, coupling, free-electron-laser

1177

A. Angelovski, M. Hansli, R. Jakoby, A. Kuhl, A. Penirschke, S. Schnepp
TU Darmstadt, Darmstadt, Germany
M. Bousonville, H. Schlarb
DESY, Hamburg, Germany
T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Funded by the Federal Ministry of Education and Research (BMBF): 05K10RDA
In the Free Electron Laser in Hamburg (FLASH) an electro-optical system is used as a Bunch Arrival time Monitor (BAM). The time-of-arrival resolution is proportional to the steepness of the beam pick-up signal at the first zero-crossing*. Future experiments will be conducted using significantly lower bunch charges resulting in a reduced signal steepness. This requires BAM pickup electrodes with increased bandwidth as introduced in **. This paper presents the implementation and measurement results of a high bandwidth cone-shaped pickup capable of operating in the frequency range up to 40 GHz. The slope steepness at the zero crossing is investigated for a simplified equivalent circuit model. RF-measurements have been performed using a non-hermetic prototype of the BAM pickups for assessing the influence of manufacturing tolerances on the sensor performance. The measurements are compared to simulation results obtained by CST PARTICLE STUDIO®.
* F. Loehl et al., Proc. of DIPAC2007, WEPB15, p. 262 (2007).
** A. Angelovski et al., "Pickup design for a high resolution Bunch Arrival time Monitor for FLASH and XFEL", DIPAC2011.

TUPC079

Sensitivity and Tolerance Analysis of a New Bunch Arrival-time Monitor Pickup Design for FLASH and XFEL

pick-up, simulation, electron, free-electron-laser

1186

A. Kuhl, A. Angelovski, R. Jakoby, A. Penirschke, S. Schnepp
TU Darmstadt, Darmstadt, Germany
M. Bousonville, H. Schlarb
DESY, Hamburg, Germany
T. Weiland
TEMF, TU Darmstadt, Darmstadt, Germany

Funding: Supported by the Graduate School of Computational Engineering at TU Darmstadt and the Federal Ministry of Education and Research (BMBF): 05K10RDA "Weiterentwickung eines Ankunftszeitmonitors"
The Free Electron Laser in Hamburg (FLASH) is equipped with Bunch Arrival Time Monitors (BAM)*, which provide for a time resolution of less than 10 fs for bunch charges higher than 0.2 nC. Future experiments, however, will aim at generating FEL light pulses from a broad range of bunch charges down to 10 pC. In these circumstances the requirements on the time resolution will no longer be fulfilled, which demands for a larger bandwidth of the pickup system. A new cone-shaped pickup, which has a bandwidth greater than 40 GHz has been proposed**. At high frequencies, small manufacturing tolerances might have great influence on the pickup signal. A sensitivity analysis of several manufacturing tolerances in the pickup design regarding their influence on the output signal was carried out (by means of CST PARTICLE STUDIO®). These results are utilized for setting limits to the manufacturing tolerances.
* M.K. Bock et al., IPAC2010, WEOCMH02, Kyoto, Japan, 2010.
** A. Kuhl et al., "Design eines hochauflösenden Ankunftszeitmonitor für FLASH", DPG Frühjahrstagung 2011, Karlsruhe, Germany.

TUPC081

Diagnostics of Femtosecond Low-charge Electron Bunches at REGAE

electron, photon, diagnostics, simulation

1192

S. Bayesteh
Uni HH, Hamburg, Germany
H. Delsim-Hashemi
DESY, Hamburg, Germany

A new linac is constructed at DESY as the electron source fo "Relativistic Electron Gun for Atomic Exploration (REGAE)". REGAE is mainly established for a Femtosecond electron diffraction experiment presenting structural information on atomic transition states occurring in the sub-hundred femtosecond time-scale. REGAE comprises a photo-cathode gun followed by normal conducting 1.5 cell RF cavity to provide sub pico-Coulomb charge of 2 to 5 MeV energy with a coherent length in the range of 30nm. In order to produce and maintain such high quality electron bunches, sophisticated single-shot diagnostics is mandatory to monitor the properties. Diagnostics include emittance, energy, energy spread and bunch length measurement. In this paper the conceptual ideas and steps toward realization of these diagnostics are presented with a detailed focus on transverse diagnostics. As for photon source of transversal diagnostics, scintillators are studied. Simulation results show which material suits the best for REGAE parameters. Layout of a home-made intensified camera is presented. The method discussed in this paper would also be advantageous for low-charge Free Electron Lasers.

TUPC086

A Setup for Single Shot Electro Optical Bunch Length Measurements at the ANKA Storage Ring

electron, storage-ring, synchrotron, radiation

1206

N. Hiller, E. Huttel, A.-S. Müller, A. Plech
KIT, Karlsruhe, Germany
F. Müller, P. Peier, V. Schlott
PSI, Villigen, Switzerland

Funding: Supported by the Initiative and Networking Fund of the Helmholtz Association under VH-NG-320. Sponsored by the German Federal Ministry of Education and Research under contract number 05K10VKC
Single shot electro optical bunch length measurements, in particular using spectral decoding, are foreseen for the ANKA storage ring. This will allow to resolve fast changes of bunch deformation and structure during the low alpha operation (2-15 ps rms bunch length). This technique uses a chirped laser pulse to probe the field induced birefringence in an electro optical crystal. The laser pulse is then analyzed in a single shot spectrometer. To obtain the birefringence modulation one can either use the near field of the electron bunch (placing the crystal close to the electron bunch in the UHV system of the storage ring), or the far field (coherent synchrotron radiation in the THz range at a THz-/IR-Beamline). The laser needs to supply: sufficient tunability of pulse length, a wide spectrum to allow for a sub-ps resolution. Additionally it must provide a mode-locked operation synchronized to the bunch revolution clock. For this purpose, a mode locked Ytterbium fibre laser system which operates at 10³⁰ nm has been developed at the Paul-Scherrer Institute in Switzerland. We give an overview over the experimental set up in the ANKA storage ring and the status of the project.

TUPC091

Operational Results of the Diamond-based Halo Monitor during Commissioning of SPring-8 XFEL (SACLA)

electron, undulator, wakefield, scattering

1218

H. Aoyagi
JASRI/SPring-8, Hyogo-ken, Japan
Y. Asano, H. Kitamura, T. Tanaka
RIKEN/SPring-8, Hyogo, Japan

Funding: This work is partly supported by Japan Society for the Promotion of Science, Grant-in-Aid for Scientific Research (c) 21604017.
Measurement of electron beam halo is very important issue for X-ray free electron laser and synchrotron radiation facilities, because the beam halo may cause radiation damage of undulator magnets. Furthermore, it may cause degradation in quality of electron beam, and radio activation of beam ducts and components. In order to prevent these situations, a diamond-based halo monitor (HM) has been developed for the SPring-8 Angstrom Compact free electron LAser (SACLA). We have achieved excellent detection limit of 0.3 fC/pulse for single-shot measurement, which corresponds to the ratio of 10^-6 to the beam core. The commissioning of the HM, which was installed at the upstream of 90m undulator, has been carried out, and it has been figured out that the intensity of the beam halo can be measured very nicely since secondary electrons and bremsstrahlung that are emitted in the accelerator components have not been observed. We also describe systematic profile measurements of the beam halo and operational results of the HM during the commissioning of SACLA.

TUPC092

Transverse C-band Deflecting Structure for Longitudinal Phase Space Diagnostics in the XFEL/SPring-8 “SACLA”

vacuum, coupling, diagnostics, emittance

1221

H. Ego
RIKEN/SPring-8, Hyogo, Japan
T. Hashirano, S. Miura
MHI, Hiroshima, Japan
H. Maesaka, Y. Otake
RIKEN Spring-8 Harima, Hyogo, Japan
T. Sakurai
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan

In SPring-8, the 8 GeV compact XFEL “SACLA” is under commissioning. A single bunch of electrons is compressed down to about 30 fs for brilliant SASE X-ray lasing. It is an important key of stable lasing to investigate the longitudinal phase space and the sliced emittance of a lasing part of the bunch by using a transverse RF deflector. We developed a high gradient C-band deflecting structure operated at 5712 MHz for the bunch diagnosis with a resolution of femtosecond regime at a limited space in the SACLA. The backward travelling-wave of the HEM11-5pi/6 mode is excited in the cylindrical structure periodically loaded with racetrack-shaped irises. The featuring irises suppress rotation of the deflection plane and generate strong cell-to-cell coupling for stable resonance. Two 1.8m-long structures were fabricated and installed in the SACLA. They successfully generated a deflection voltage over 40 MV and pitched the bunch at the zero-crossing RF phase. In this paper, we present the details of the fabrication and the deflecting performance of the structures applied to the diagnosis.

TUPC110

Ultrashort Bunch Train Longitudinal Diagnostics using RF Deflecting Structure

cavity, diagnostics, betatron, emittance

1275

Y. Yang, H. Chen, Y.-C. Du, W.-H. Huang, C. Li, L.X. Yan
TUB, Beijing, People's Republic of China

Ultrashort electron bunch train has been produced using UV laser stacking in Tsinghua University. With an S-band deflecting cavity inserted into the Tsinghua Thomson Scattering beamline, it is possible to characterize the bunch train longitudinal property. This paper briefly introduced the measurement layout in our lab and reported the recent experiment results, including bunch train profile measurement and longitudinal phase space. The main sources of error are also discussed.

TUPC124

Laser Wire Emittance Measurement Line at CLIC*

emittance, photon, collider, electron

1308

H. Garcia, Yu.A. Kubyshin
UPC, Barcelona, Spain
T. Aumeyr, G.A. Blair
JAI, Egham, Surrey, United Kingdom
D. Schulte, F. Stulle
CERN, Geneva, Switzerland

A precise measurement of the transverse beam size and beam emittances upstream of the final focus is essential for ensuring the full luminosity at future linear colliders. A scheme for the emittance measurements at the RTML line of the CLIC using laser-wire beam profile monitors is described. A lattice of the measurement line is discussed and results of simulations of statistical and machine-related errors and of their impact on the accuracy of the emittance reconstruction are given. Modes of operation of the laser wire system and its main characteristics are discussed.

TUPC133

Instrumentation for the 12 GHz Stand-alone Test-stand to Test CLIC Acceleration Structures

electron, vacuum, diagnostics, ion

1335

M. Jacewicz, R.J.M.Y. Ruber, V.G. Ziemann
Uppsala University, Uppsala, Sweden
J.W. Kovermann
CERN, Geneva, Switzerland

Vacuum breakdown is one of the primary limitations in the design and construction of high energy accelerators operating with warm accelerating structures (ACS) such as CLIC linear collider because the mechanisms that cause the breakdown are still a mystery. The ongoing experimental work is trying to benchmark the theoretical models focusing on the physics of vacuum breakdown which is responsible for the observed discharges. The CLIC collaboration is preparing a dedicated 12 GHz test-stand to observe the characteristics of the RF discharges and their eroding effects on the ACS. The instrumentation for the test-stand must be versatile and allow for the conditioning of the ACS with measurements of the breakdown rates at different power levels as well as detection of the dark current and light emission directly relevant to breakdown physics. For that purpose we are developing 2 novel instruments. A pepper-pot chamber with an external magnetic spectrometer for measurement of the spatial and energy distributions of the electrons emitted from the ACS and an optical laser system for probing the ACS to observe the effect of a discharge on the transmitted light.

TUPC139

Overview of the CLIC Beam Instrumentation

linac, cavity, beam-losses, instrumentation

1350

T. Lefèvre
CERN, Geneva, Switzerland

Driven by beam dynamic considerations the Compact Linear Collider (CLIC) is expected to require extremely tight tolerances on most beam parameters. An important milestone was reached in 2011 with the completion of the CLIC conceptual design report. In this context the requirements for CLIC beam instrumentation has been reviewed and studied in detail for the whole accelerator complex with the aim of demonstrating feasibility. A preliminary choice has been made for every CLIC instrument, serving as a baseline scenario for the next phase of the project which will concentrate on the detailed design, engineering and test of CLIC devices. Whenever possible existing solutions have been studied, focusing on any improvements necessary to meet the CLIC performance criteria. When no such devices exists, or if cost considerations come into play, new technologies have been under study. Several prototypes are already well advanced and are currently under test. This paper presents an overview of CLIC beam instrumentation, the possible reach of their performance and an outlook on future developments.

TUPC142

The Particle Identification System for the MICE Beamline Characterization

emittance, beam-losses, electron, solenoid

1356

M. Bonesini
INFN MIB, MILANO, Italy
Y. Karadzhov
DPNC, Genève, Switzerland

The International Muon Ionization Cooling Experiment (MICE) will carry out a systematic investigation of a ionization cooling section of a muon beam, for the future Neutrino Factory and the future Muon Collider. As the emittance measurement will be done on a particle-by-particle basis, a sophisticated beam instrumentation is needed to measure both particle coordinates and timing vs RF in a harsh environment due to high particle rates, fringe magnetic fields and RF backgrounds. A PID system, based on three time-of-flight stations (with resolutions up to 50-60 ps), two Aerogel Cerenkov counters and a KLOE-like calorimeter (KL) has been constructed and has allowed the commissioning of the MICE muon beamline in 2010. It will be complemented in 2011 by an Electron Muon Ranger to determine the muon range at the downstream end of the cooling section. Detector performances, as obtained in the 2010 run, will be shown and the use of PD detectors for the beamline characterization, including a preliminary measure of emittance, fully illustrated.

TUPC151

Cherenkov Fibre Optic Beam Loss Monitor at ALICE

beam-losses, photon, electron, monitoring

1383

A. Intermite
The University of Liverpool, Liverpool, United Kingdom
A. Intermite, M. Putignano, A. Wolski
Cockcroft Institute, Warrington, Cheshire, United Kingdom

The need for real-time monitoring of beam losses, including evaluation of their intensity and the localization of their exact position, together with the possibility to overcome the limitations due to the reduced space for the diagnostics, makes optical fibres (using the Cherenkov Effect) one of the most suitable and explored candidate for beam loss monitoring. In this contribution, we report on an optical fibre beam loss monitor based on large numerical aperture pure silicon fibres and silicon photomultipliers, tested at ALICE, Daresbury Laboratories, UK. The original design of the sensor has the advantage to combine the functions of a real time detector and a transmission line. It also allows reading the signals independently and determining the time and position of the losses without the use of an external trigger.

TUPC158

Micron-scale Laser-wire at the ATF-II at KEK Commissioning and Results

electron, optics, photon, diagnostics

1401

L.J. Nevay, G.A. Blair, S.T. Boogert, L. Corner, L.C. Deacon, V. Karataev, R. Walczak
JAI, Oxford, United Kingdom
A.S. Aryshev, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

We present the first results from the commissioning of the upgraded laser-wire experiment at the Accelerator Test Facility 2 (ATF2) at KEK. A new laser transport line and beam diagnostics were used to collide 150 mJ, 167 ps long laser pulses with 1.28 GeV, 30 ps long electron bunches to measure the vertical transverse size. Additionally, a new detector was installed with a reduced area for lower background. Initial scans showing a convoluted beam size of 19.2 ± 0.2 microns were used to tune the electron beam optics and reduce this down to 8.1 ± 0.1 microns. Laser pulse energy and charge dependency were investigated showing a linear relationship in both with a minimum laser energy of 20 mJ required for observable signal with this laser and setup.

TUPC169

Single-shot Electro-optic Sampling of Coherent Transition Radiation at the A0 Photoinjector

polarization, radiation, diagnostics, electron

1431

T.J. Maxwell, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
J. Ruan, R.M. Thurman-Keup
Fermilab, Batavia, USA

Funding: Work supported by Fermi Research Alliance, LLC under U.S. Dept. of Energy Contract No. DE-AC02-07CH11359, and Northern Illinois Univ. under US Dept. of Defense DURIP program Contract N00014-08-1-10⁶⁴.
Future collider applications and present high-gradient laser plasma wakefield accelerators operating with picosecond bunch durations place a higher demand on the time resolution of bunch distribution diagnostics. This demand has led to significant advancements in the field of electro-optic sampling over the past ten years. These methods allow the probing of diagnostic light such as coherent transition radiation (*) or the bunch wakefields (**) with sub-picosecond time resolution. Potential applications in shot-to-shot, non-interceptive diagnostics continue to be pursued for live beam monitoring of collider and pump-probe experiments. Related to our developing work with electro-optic imaging, we present results on single-shot electro-optic sampling of the coherent transition radiation from bunches generated at the A0 photoinjector.
* J. van Tilborg et al., Phys. Rev. Lett. 96, 014801 (2006).
** M. J. Fitch et al., Phys. Rev. Lett. 87 034801 (2001).

TUPC171

2D Optical Streaking for Ultra-short Electron Beam Diagnostics

electron, simulation, diagnostics, linac

1437

L. Wang, Y.T. Ding, Z. Huang
SLAC, Menlo Park, California, USA

We propose a novel approach to measure the short electron bunch profile at micrometer level. Low energy electrons generated during beam-gas ionization are simultaneously modulated by the transverse electric field of a circularly-polarized laser, and then they are collected at a down-stream screen where the angular modulation are converted to a circular shape there. The longitudinal bunch profile is simply represented by the angular distribution of the electrons on the screen. We only need to know the laser wavelength for calibration and there is no phase synchronization problem. Meanwhile the required laser power is also relatively low in this setup. Some simulations examples and resolution of this method will be discussed.

TUPC178

Charge Lifetime Study of K2CsSb Photocathode Inside a Jlab DC High Voltage Gun

cathode, vacuum, gun, high-voltage

1443

R.R. Mammei, M. Poelker, R. Suleiman
JLAB, Newport News, Virginia, USA
J.L. McCarter
UVa, Charlottesville, Virginia, USA
T. Rao, J. Smedley
BNL, Upton, Long Island, New York, USA

Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. DOE
Two photocathodes are frequently considered for generating high average current electron beams and/or beams with high brightness for current and future accelerator applications: GaAs:Cs and K2CsSb. Each photocathode has advantages and disadvantages, and need to demonstrate performance at “production” accelerator facilities. To this end a K2CsSb photocathode was manufactured at Brookhaven National Lab and delivered to Jefferson Lab within a compact vacuum apparatus at pressure ~ 5x10^-11 Torr. This photocathode was installed inside a dc high voltage photogun biased at voltages up to 200 kV, and illuminated with laser light at 440 or 532 nm, to generate beams up to 20 mA. Photocathode charge lifetime measurements indicate that under some conditions this cathode has exceptionally high charge lifetime, without measurable QE decay, even from the center of the photocathode where operation using GaAs photocathodes is precluded due to ion bombardment. These studies also suggest a complex QE decay mechanism likely related to chemistry and localized heating via the laser beam.

TUPO002

High Flux Polarized Gamma Rays Production: First Measurements with a Four-mirror Cavity at the ATF

cavity, electron, positron, damping

1446

N. Delerue, J. Bonis, I. Chaikovska, R. Chiche, R. Cizeron, M. Cohen, P. Cornebise, R. Flaminio, D. Jehanno, F. Labaye, M. Lacroix, Y. Peinaud, L. Pinard, V. Soskov, A. Variola, Z.F. Zomer
LAL, Orsay, France
T. Akagi, S. Miyoshi
Hiroshima University, Graduate School of Advanced Sciences of Matter, Higashi-Hiroshima, Japan
S. Araki, Y. Funahashi, Y. Honda, T. Omori, H. Shimizu, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
E. Cormier
CELIA, Talence, France
T. Takahashi
Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan

Funding: ANR, IN2P3
The next generation of e+/e^- colliders will require the production of a very intense flux of gamma rays to allow polarized positrons to be produced in sufficient quantities. To demonstrate that this can be achieved a four-mirror cavity has recently been installed at the Accelerator Test Facility (ATF) at KEK to produce a high flux of polarized gamma rays by inverse Compton scattering. A four-mirror non-planar geometry is used to ensure the polarization of the gamma rays produced. The main mechanical features of the cavity are presented. A fibre amplifier is used to inject about 10W in the high finesse cavity with a gain of 1000. A digital feedback system is used to keep the cavity at the length required for the optimal power enhancement. First preliminary measurements show that on some beam crossings the interactions produce more than 25 photons with an average energy of about 24 MeV. Several upgrades currently in progress are described.

TUPO004

Generation of Attosecond Soft X-ray Pulses in a Longitudinal Space Charge Amplifier

undulator, electron, space-charge, radiation

1449

M. Dohlus, E. Schneidmiller, M.V. Yurkov
DESY, Hamburg, Germany

A longitudinal space charge amplifier (LSCA), operating in soft x-ray regime, was recently proposed. Such an amplifier consists of a few amplification cascades (focusing channel and chicane) and a short radiator undulator in the end. Broadband nature of LSCA supports generation of few-cycle pulses as well as wavelength compression. In this paper we consider an application of these properties of LSCA for generation of attosecond x-ray pulses. It is shown that a compact and cheap addition to the soft x-ray free electron laser facility FLASH would allow to generate 60 attosecond (FWHM) long x-ray pulses with the peak power at 100 MW level and a contrast above 98%.

TUPO005

Design Optimization for a Non-Planar Undulator for the JETI-Laser Wakefield Accelerator in Jena

undulator, electron, radiation, wakefield

1452

V. Afonso Rodriguez, T. Baumbach, A. Bernhard, G. Fuchert, A. Keilmann, P. Peiffer, C. Widmann
KIT, Karlsruhe, Germany
M. Kaluza, M. Nicolai
IOQ, Jena, Germany
R. Rossmanith
Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany

In a laser wakefield accelerator (LWFA), excited by a femtosecond laser pulse electrons are accelerated to several 100 MeV within a few centimeters. The energy spread of the electron beam is relatively large and varies from shot to shot. In order to obtain monochromatic photons in an undulator despite the energy spread, the following idea was proposed. Two bending magnets and a drift space in between produces dispersion so that particles with different energies have different transverse positions. The beam enters a non-planar undulator, e.g. cylindrical pole geometry, where the K-value also varies with transverse position. If the two variations in the transverse direction (particle energy and K-value) compensate each other the generated light is more monochromatic than with a conventional planar undulator. In this paper such a modified undulator design optimized for the JETI-LWFA in Jena is presented. An experiment to test this concept is in preparation.

TUPO008

Electron Linac Optimization for Driving Bright Gamma-ray Sources based on Compton Back-scattering

electron, photon, linac, emittance

1461

L. Serafini, F. Broggi, C. De Martinis, D. Giove
Istituto Nazionale di Fisica Nucleare, Milano, Italy
D. Alesini, P. Antici, A. Bacci, M. Bellaveglia, R. Boni, E. Chiadroni, G. Di Pirro, A. Esposito, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, E. Pace, A.R. Rossi, B. Spataro, P. Tomassini, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
C. Maroli, V. Petrillo
Universita' degli Studi di Milano, Milano, Italy
M. Migliorati, A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy

We study the optimal lay-out and RF frequency for a room temperature GeV-class Electron Linac aiming at producing electron beams that enhance gamma-ray sources based on Compton back-scattering. These emerging novel sources, generating tunable, mono-chromatic, bright photon beams in the range of 5-20 MeV for nuclear physics as well as nuclear engineering, rely on both, high quality electron beams and J-class high repetition-rate synchronized laser systems in order to achieve the maximum spectral density of the gamma-ray beam (# photons/sec/eV). The best option among the conventionally used RF linac-bands (S, C, X) and possible hybrid schemes will be analyzed and discussed, focusing the study in terms of best performances for the gamma-ray source, its reliability and compactness. We show that the best possible candidates for a Gamma-ray driver are quite similar to those of FEL Linacs.

TUPO012

Stable Planner Type Four-mirror Cavity Development for X-ray Production as Basic Development of Quantum Beam Technology Program

cavity, injection, superconducting-RF, target

1470

H. Shimizu, Y. Higashi, Y. Honda, J. Urakawa
KEK, Ibaraki, Japan

As the development of quantum beam technology program, a facility to produce a semi-monochromatic X-ray via inverse Compton scattering with an electron beam accelerated by a superconducting RF cavity and a fiber amplified high power laser stacked in an external optical cavity system are now under construction. To achieve high brightness of Compton X-ray, we introduced a chicane with about a 1m-long zero dispersion straight section that includes IP. Head on collision scheme improves the yield of X-ray, but to do so, a huge and stout external optical cavity system must be needed. According to this demand, we develop a quite tolerable planner type four-mirror cavity with movable mirror mount system. In this paper, results obtained by the cavity construction and also laser development activities are described.

TUPO013

Development of Pulse Width Measurement Techniques in a Picosecond Range of Ultra-short Gamma Ray Pulses

photon, electron, storage-ring, scattering

1473

Y. Taira, M. Hosaka, K. Soda, N. Yamamoto
Nagoya University, Nagoya, Japan
M. Adachi, M. Katoh, H. Zen
Sokendai - Okazaki, Okazaki, Aichi, Japan
T. Tanikawa
UVSOR, Okazaki, Japan

Funding: This work was supported by Grants-in-Aid for Scientific Research from Japan Society for the Promotion of Science (JSPS).
We are developing the ultra-short gamma ray pulse source with the energy of MeV region based on laser Compton scattering at the 750 MeV electron storage ring, UVSOR-II. Gamma rays with pulse width of sub-picosecond range can be generated by injecting femtosecond laser pulses into the electron beam from the vertical 90-degree direction* because the electron beam circulating in the storage ring is focused more tightly in the vertical direction than in the longitudinal direction. The energy, intensity, and pulse width of the gamma rays can be tuned by changing the collision angle between the electron beam and the laser. We are developing pulse width measurement techniques of ultra-short gamma ray pulses at present. As the first step of the pulse width measurement, we used a fast response photodetector, Geiger-mode APD, the time resolution of which is few hundreds picoseconds. Although we cannot measure the pulse width of the gamma rays with sub-picosecond range using this detector, we could measure the pulse width of the gamma rays as 430 ps or less by measuring the timing of Cherenkov radiations generated from the gamma rays.
* Y. Taira et al., Nucl. Instrum. Meth. A, in press, 2010.

TUPO014

High-flux Gamma-ray Generation by Laser Compton Scattering in the SAGA-LS Storage Ring

photon, storage-ring, survey, electron

1476

T. Kaneyasu, Y. Iwasaki, S. Koda, Y. Takabayashi
SAGA, Tosu, Japan

We constructed an experimental setup for high-flux gamma-ray generation by laser Compton scattering (LCS) in the SAGA-LS storage ring. The SAGA-LS is a synchrotron radiation (SR) facility consisting of a 255 MeV injector linac and a 1.4 GeV storage ring. We employed a CO2 laser having a wavelength of 10.6 micrometer to produce gamma-rays in the few MeV region in conjunction with the SR user time. The LCS gamma-ray up to the maximum energy of 3.5 MeV is generated via head-on collision between the laser photons and the 1.4 GeV stored beam. Since the energy acceptance of the storage ring is well above the maximum gamma-ray energy, the LCS experiment can be performed without reducing the beam lifetime. As a first step for high-flux gamma-ray generation, we use a small 10 W CO2 laser for beam test. The LCS event rate is designed to be 2·10⁸ ph/s with a beam current of 300 mA and a laser power of 10 W. A further increase of the LCS event rate in the order of 10¹0 ph/s is expected when a kW class laser is utilized. We report on the characteristics of the LCS gamma-rays observed in the low current beam test and an experimental result for evaluating the gamma-ray flux at a current of 300 mA.

TUPO023

Narrow Spectral Bandwidth Optimization of Compton Scattering Sources

electron, scattering, simulation, emittance

1488

F. Albert, S.G. Anderson, S.M. Betts, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, T.L. Houck, R.A. Marsh, M. J. Messerly, C. Siders, S.S.Q. Wu
LLNL, Livermore, California, USA

We will be presenting the theoretical and numerical design and optimization of Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering sources. A new precision source with up to 2.5 MeV photon energies, enabled by state of the art laser and x-band linac technologies, is currently being built at LLNL. Various aspects of the theoretical design, including dose and brightness optimization, will be presented. We will review the potential sources of spectral broadening, in particular due to the electron beam properties. While it is also known that nonlinear effects occur in such light sources when the laser normalized potential is close to unity, we show that these can appear at lower values of the potential. A three dimensional analytical model and numerical benchmarks have been developed to model the source characteristics based on given laser and electron beam distributions, including nonlinear spectra. Since MEGa-ray sources are being developed for precision applications such as nuclear resonance fluorescence, assessing spectral broadening mechanisms is essential.
This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

TUPO024

Precision X-band Linac Technologies for Nuclear Photonics Gamma-ray Sources

gun, electron, photon, scattering

1491

F.V. Hartemann, F. Albert, S.G. Anderson, C.P.J. Barty, A.J. Bayramian, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, T.L. Houck, R.A. Marsh, M. J. Messerly, S.S.Q. Wu
LLNL, Livermore, California, USA
C. Adolphsen, A.E. Candel, T.S. Chu, M.V. Fazio, E.N. Jongewaard, Z. Li, C. Limborg-Deprey, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou
SLAC, Menlo Park, California, USA
D. Cutoiu
Horia Hulubei National Institute for Physics and Nuclear Engineering, Bucharest, Romania
D. Ighigeanu, M. Toma
INFLPR, Bucharest - Magurele, Romania
V.A. Semenov
UCB, Berkeley, California, USA

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Nuclear photonics is an emerging field of research requiring new tools, including high spectral brightness, tunable gamma-ray sources; high photon energy, ultrahigh-resolution crystal spectrometers; and novel detectors. This presentation focuses on the precision linac technology required for Compton scattering gamma-ray light sources, and on the optimization of the laser and electron beam pulse format to achieve unprecedented spectral brightness. Within this context, high-gradient X-band technology will be shown to offer optimal performance in a compact package, when used in conjunction with the appropriate pulse format, and photocathode illumination and interaction laser technologies.

TUPS012

The Present Status of Vacuum System of XFEL in SPring-8

vacuum, shielding, electron, undulator

1542

T. Bizen
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
T. Hasegawa
RIKEN/SPring-8, Hyogo, Japan

The vacuum component assembly and installation were completed by February in 2011. The total length of the vacuum system is about 630 m. A 455 sputter ion pumps and a 10⁸ NEG cartridge pumps generate vacuum. The average pressures are on the order of ·10^-7 Pa or less. The flange developed for C-band waveguide shows high reliability of vacuum seal.

TUPS031

The Installation of One 14 Meter Cell of TPS Vacuum System

vacuum, photon, synchrotron, site

1599

H.P. Hsueh, C.K. Chan, C.H. Chang, C.-C. Chang, C.L. Chen, C.M. Cheng, Y.T. Cheng, G.-Y. Hsiung, S-N. Hsu, I.T. Huang, T.Y. Lee, H.Y. Yan, Y.C. Yang, C.S. huang
NSRRC, Hsinchu, Taiwan
J.-R. Chen
National Tsing Hua University, Hsinchu, Taiwan

The construction of a new 3 GeV synchrotron facility, Taiwan Photon Source, is ongoing. The vacuum system has been designed with off-site baking for arc section from sector gate valve to sector gate valve. There is no flange used in this arc section besides the two ends connected to sector gate valves. It is a tedious works for install such long vacuum system with aluminum chambers. In this poster, all the detailed installation procedures will be described. All the precaution inspection procedures for all vacuum components to prevent failed components to be installed will also be described. Every three weeks, one cell will be assembled and stored. Experience is being learned and could be used for the vacuum system of future new accelerator like FEL and others.

TUPS056

Synchronizing GEANT and 3D CAD - A Collaborative Engineering Study at ILD

simulation, free-electron-laser, electron

1659

L. Hagge, S. Eucker, B. List, S. Sühl, N. Welle
DESY, Hamburg, Germany

The design of a detector for a high-energy physics experiment is a complex task, driven by two different communities: The scientists aim to optimize the detector performance, while engineers are tasked to provide a design that can actually be built. Both groups have their own specific tools (e.g. GEANT versus 3D CAD systems) that are employed to model the detector and improve its design. The ensuing models need to be compared and synchronized at regular intervals, so that optimizations made to the physics simulation model are propagated to the engineering world, and engineering solutions are reflected properly in the physics simulation. Based on experience from the European XFEL project, DESY is providing tools and processes for establishing this synchronization at a very early stage in the design of the International Large Detector (ILD) for the International Linear Collider (ILC). They have been used to analyze compliance and differences of the ILD engineering design and physics simulation models. The poster introduces tools and process and presents first results and lessons learned.

WEOAA01

The ThomX Project

injection, feedback, cavity, synchrotron

1903

A. Variola
LAL, Orsay, France

Funding: Work supported by the EQUIPEX program, the Ile de France region, CNRS-IN2P3 and Université Paris Sud XI
ThomX is a Compton source project in the range of the hard X rays (40 / 90 keV). The machine is composed of an injector Linac and a storage ring where an electron bunch collides with a laser pulse accumulated in a Fabry-Perot resonator. The final goal is to provide an X-rays average flux of 1011/10¹³ ph/s. The emitted flux will be characterized by a dedicated X-ray line. Different users are partners in the ThomX project, especially in the area of medical science and cultural heritage. Their main goal will be the transfer of all the experimental techniques developed on big synchrotron rings to these more compact and flexible machines. The project ThomX has recently been funded and will be located on the Orsay University campus. In this article the project and its associated scientific interest are presented.

Slides WEOAA01 [5.947 MB]

WEXB01

Advanced Acceleration Schemes

electron, plasma, acceleration, wakefield

1945

P.A. Naik, P.D. Gupta, B.S. Rao
RRCAT, Indore (M.P.), India

Review the progress and prospects of advanced acceleration concepts, including plasma acceleration, laser acceleration, and dielectric accelerators. Report ongoing and near-future experiments, and longer-term prospects for applications (e.g. compact X-ray sources, linear colliders, hadrontherapy).

Slides WEXB01 [8.636 MB]

WEOAB01

Highly Polarized and High Quantum Efficiency Electron Source Using Transmission-type Photocathode

electron, gun, brightness, polarization

1950

N. Yamamoto, F. Ichihashi, A. Mano, T. Nakanishi, Y. Takeda, T. Ujihara
Nagoya University, Nagoya, Japan
X.G. Jin
Institute for Advanced Research, Nagoya, Japan

The GaAs-type semiconductor photocathodes (PCs) with a negative electron affinity surface have been used as a polarized electron source and are expected as electron sources for next generation accelerators, such as Linear Colliders and Energy Recovery Linacs. Recently, we have developed transmission-type photocathodes (T-PCs).　By using T-PCs, polarized electron beam is extracted from the back-side of laser irradiation-side.　This scheme offers great merits in designing electron guns, such as short focusing of the laser light for a high brilliance electron beam and a simple geometrical structure avoiding an interference problem between the laser and the electron beam. The layer structure of the MOVPE-grown superlattice photocathode and the performance of 90% polarization, a super high brilliance, and a high quantum efficiency will be reported.

Slides WEOAB01 [6.007 MB]

WEOAB03

The Production of High Quality Electron Beams in the ALPHA-X Laser Wakefield Accelerator

electron, plasma, emittance, radiation

1956

S.M. Wiggins, M.P. Anania, C. Aniculaesei, E. Brunetti, S. Cipiccia, B. Ersfeld, M.R. Islam, R.C. Issac, D.A. Jaroszynski, G.G. Manahan, R.P. Shanks, G.H. Welsh
USTRAT/SUPA, Glasgow, United Kingdom
W.A. Gillespie
University of Dundee, Nethergate, Dundee, Scotland, United Kingdom
A. MacLeod
UAD, Dundee, United Kingdom

Funding: The U.K. EPSRC, the EC's Seventh Framework Programme (LASERLAB-EUROPE / LAPTECH, grant agreement no. 228334) and the Extreme Light Infrastructure (ELI) project.
The Advanced Laser-Plasma High-Energy Accelerators towards X-rays (ALPHA-X) programme is developing laser-plasma accelerators for the production of ultra-short electron beams as drivers of incoherent and coherent radiation sources from plasma and magnetic undulators. Here we report on the latest laser wakefield accelerator experiments on the University of Strathclyde ALPHA-X accelerator beam line looking at high quality electron beams. ALPHA-X uses a 26 TW Ti:sapphire laser (energy 900 mJ, duration 35 fs) focused into a helium gas jet (nozzle length 2 mm) to generate high quality monoenergetic electron beams with central energy in the range 80-180 MeV. The beam is fully characterized in terms of the charge, bunch length, energy spread and transverse emittance. The energy spectrum (with less than 1% measured energy spread) is obtained using a high resolution magnetic dipole imaging spectrometer while pepper-pot mask measurements show that the normalized transverse emittance is as low as 1.1 pi mm mrad (resolution limited). The conditions needed to obtain this high quality are discussed.

Slides WEOAB03 [2.904 MB]

WEYB01

Diagnostics for Ultra-low Emittance Beams

polarization, radiation, emittance, optics

1959

J.W. Flanagan
KEK, Ibaraki, Japan

The achievement in recent years of beams with vertical emittance of a few pico-meters in a number of electron storage rings has presented challenges for diagnostics capable of beam size measurements in this regime. A number of different approaches have been developed for various machines (e.g. laser wire; interferometer; Shintake monitor; coded aperture; compound refractive lens). This presentation will review and compare the different methods, and discuss their strengths, weaknesses, ultimate limitations, and the situations where they might be appropriate; and consider possible future directions.

Slides WEYB01 [2.553 MB]

WEOBB02

Bunch Length Diagnostic with Sub-femtosecond Resolution for High Brightness Electron Beams

undulator, electron, simulation, cavity

1967

G. Andonian, E. Hemsing, P. Musumeci, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
A.Y. Murokh
RadiaBeam, Santa Monica, USA
D. Xiang
SLAC, Menlo Park, California, USA

Next generation light sources require electron beams with high peak currents, typically achieved by compression techniques. The temporal diagnosis of these ultra-short beams demands enhanced resolution. We describe a scheme to achieve a temporal resolution on the order of sub-femtoseconds. The scheme is based on encoding the longitudinal profile of the beam on a transverse angular modulation, based on an interaction between the electron beam and a high-power laser in an undulator. This imposes a fast-sweep of the beam, on the order of sub-femtoseconds. A subsequent sweep in the orthogonal dimension by an rf deflecting cavity, imposes a "slow-sweep" on the order of sub-picoseconds. In this paper, we demonstrate applicability of this diagnostic scheme at the BNL ATF and specify the techniques required for practical applicability.

Slides WEOBB02 [1.120 MB]

WEIB01

Chasing Femtoseconds – How Accelerators Can Benefit from Economies of Scale in Other Industries

optics, scattering, polarization, controls

1973

M. Vidmar, J. Tratnik
University of Ljubljana, Faculty of Electrical Engineering, Ljubljana, Slovenia
P.L. Lemut
COBIK, Solkan, Slovenia

Building accelerators we frequently push the limits of what is possible in terms of performance. When trying to solve a very challenging engineering problem, we normally resort to specialization; we narrow our focus. This talk suggests a possible alternative path. Huge benefits and great results can be achieved by combining creative ideas and approaches with ideas and solutions borrowed from the economies of scale like telecommunications. The aim of the talk is to show possibilities for combining ideas, technologies and components from different industries into innovative products.

Slides WEIB01 [0.799 MB]

WEPC051

Effect of Compton Scattering on the Electron Beam Dynamics at the ATF Damping Ring

electron, scattering, damping, cavity

2127

I. Chaikovska, C. Bruni, N. Delerue, A. Variola, Z.F. Zomer
LAL, Orsay, France
K. Kubo, T. Naito, T. Omori, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan

Compton scattering provides one of the most promising scheme to obtain polarized positrons for the next generation of e⁺e⁻ colliders. Moreover it is an attractive method to produce monochromatic high energy polarized gammas for nuclear applications and X-rays for compact light sources. In this framework a four-mirror Fabry-Perot cavity has been installed at the Accelerator Test Facility (ATF - KEK, Tsukuba, Japan) and will be used to produce an intense flux of polarized gamma rays by Compton scattering. For electrons at the energy of the ATF (1.28GeV) Compton scattering may result in a shorter lifetime due to the limited bucket acceptance. We have implemented the effect of Compton scattering on a 2D tracking code with a Monte-Carlo method. This code has been used to study the longitudinal dynamics of the electron beam at the ATF damping ring, in particular the evolution of the energy spread and the bunch length under Compton scattering. The results obtained are presented and discussed. Possible methods to observe the effect of Compton scattering on the ATF beam are proposed.

WEPC075

ITEP-TWAC Progress Report

ion, proton, injection, target

2193

N.N. Alexeev, P.N. Alekseev, V. Andreev, A. Balabaev, V.I. Nikolaev, A.S. Ryabtsev, Yu.A. Satov, V.A. Schegolev, B.Y. Sharkov, A. Shumshurov, V.P. Zavodov
ITEP, Moscow, Russia

The program of the ITEP-TWAC Facility upgrade for next three years has been approved last year in the frame of National Research Center Kurchatov Institute taking up ITEP in accordance with government decision. It includes expanding of multimode using proton and heavy ion beams in different applications on a base of new accelerator technologies development. The laser ion source advantage of high temperature plasma generation has to be transformed to high current and high charge state ion beam of Z/A up to 0.4 for elements with A ~ 60 to be effectively stacked in the accumulator ring with multiple charge exchange injection technique. The new high current heavy ion RFQ section is in progress for the beam test. Accelerating system of accumulator ring U-10 is modified to increase compression voltage for stacked beam by factor of four. Design of proton injection and beam slow extraction for UK ring is performed for its utilizing as self-depending synchrotron in medical application and for imitation of cosmic radiation. The machine status analysis and current results of activities aiming at both subsequent improvement of beam parameters and expanding beam applications are presented.

WEPC143

First Operation of the SACLA Control System in SPring-8

controls, electron, monitoring, status

2325

R. Tanaka, Y. Furukawa, T. Hirono, M. Ishii, M. Kago, A. Kiyomichi, T. Masuda, T. Matsumoto, T. Matsushita, T. Ohata, C. Saji, T. Sugimoto, M. Yamaga, A. Yamashita
JASRI/SPring-8, Hyogo-ken, Japan
T. Fukui, T. Hatsui, N. Hosoda, T. Ohshima, T. Otake, Y. Otake, H. Takebe
RIKEN/SPring-8, Hyogo, Japan
H. Maesaka
RIKEN Spring-8 Harima, Hyogo, Japan

The control system design of the X-ray free electron laser facility (SACLA) in SPring-8 has started in 2006. Now, the facility has completed to start beam commissioning in February 2011. The electron beams were successfully accelerated up to 8 GeV and the first SASE X-ray was observed. The control system adopts the 3-tier standard model by using MADOCA framework developed in SPring-8. The upper control layer consists of Linux PCs for operator consoles, Sybase RDBMS for data logging and FC-based NAS for NFS. The lower layer consists of VMEbus systems with off-the-shelf I/O boards and specially developed boards for RF waveform processing with high precision. Solaris OS is adopted to operate VMEbus CPU. The PLC is used for slow control and connected to the VME systems via FL-net. The Device-net is adopted for frontend device control to reduce the number of signal cables. Some of VMEbus systems have a beam-synchronized data-taking system to meet 60Hz electron beam operation for the beam tuning diagnostics. The accelerator control system has gateways not only to monitor device status but also control the tuning points of the facility utility system, especially cooling water.

WEPS033

Matching a Laser Driven Proton Injector to a CH - Drift Tube Linacs

proton, solenoid, acceleration, electron

2556

A. Almomani, M. Droba, U. Ratzinger
IAP, Frankfurt am Main, Germany
I. Hofmann
HIJ, Jena, Germany

Experimental results and theoretical predictions in laser acceleration of protons achieved energies of ten to several tens of MeV. The LIGHT project (Laser Ion Generation, Handling and Transport) is proposed to use the PHELIX laser accelerated protons and to provide transport, focusing and injection into a conventional accelerator. This study demonstrates transport and focusing of laser-accelerated 10 MeV protons by a pulsed 18 T magnetic solenoid. The effect of co-moving electrons on the beam dynamics is investigated. The unique features of the proton distribution like small emittances and high yield of the order of 10¹3 protons per shot open new research area. The possibility of creating laser based injectors for ion accelerators is addressed. With respect to transit energies, direct matching into DTL's seems adequate. The bunch injection into a proposed CH⁻ structure is under investigation at IAP Frankfurt. Options and simulation tools are presented.

WEPZ002

Chromatic, Geometric and Space Charge Effects on Laser Accelerated Protons Focused by a Solenoid

solenoid, proton, emittance, ion

2766

H.Y. Al-Omari, U. Ratzinger
IAP, Frankfurt am Main, Germany
I. Hofmann
GSI, Darmstadt, Germany

We studied numerically emittance and transmission effects by chromatic and geometric aberrations, with and without space charge, for a proton beam behind a solenoid in the laser proton experiment LIGHT at GSI. The TraceWin code was employed using a field map for the solenoid and an initial distribution with exponential energy dependence close to the experiment. The results show a strong effect of chromatic, and a relatively weak one of geometric aberrations as well as dependence of proton transmission on distance from the solenoid. The chromatic effect has an energy filtering property due to the finite radius beam pipe. Furthermore, a relatively modest dependence of transmission on space charge is found for p production intensity below 10¹1.

WEPZ005

Field Calculations to obtain Attosecond/Femtosecond Electron Bunches

cathode, electron, injection, radiation

2772

V.A. Papadichev
LPI, Moscow, Russia

Obtaining short electron bunches of attosecond and femtosecond duration in a combined quasi-static and laser electric field [* - ****] requires careful field formation in the cathode region. First, the maximum of laser electric field normal to the cathode plate, depending on the incidence angle, was found employing Fresnel formulae using complex dielectric permittivity of metals. Second, laser field enhancement on cathode spikes was calculated for the case of an ellipsoid in a qusi-static approximation (laser wavelength larger than spike dimensions). Field enhancement is approximately proportional to the square of the ratio of major to minor axes of ellipsoid. Thus, enhancement factors as large as 100 - 1000 are obtainable, allowing to reduce laser power by 10 thousand to 1 million times.
* V.A.Papadichev, Patent RU 2 269 877 C1, 10.02.06, Bull. 4.
** V.A.Papadichev, Proc. EPAC08, p.2812.
*** V.A.Papadichev, Proc. EPAC08, p.2815.
**** V.A.Papadichev, Proc. IPAC'10, p. 4372

WEPZ006

Forming Attosecond Electron Pulses in Space-charge Dominated Regime

electron, radiation, acceleration, bunching

2775

V.A. Papadichev
LPI, Moscow, Russia

Production of high-current attosecond electron pulses requires studying of the final bunching stage, which inevitably is space-charge dominated [*, **, ***]. Two models are studied, both allow solving a one-dimensional equation of motion. The first is for a spherical bunch, which corresponds to a short emitted pulse from a one-spike cathode of diameter approximately equal to its length. The second model is suited for pulses emitted from a multi-spike or multi-blade cathode. The bunch in the latter case is a thin plate and its evolution can be studied by also solving one-dimensional equation of motion. It was shown that bunches of 10-attosecond (as) duration with peak current of dozens of amperes can be obtained when using a carbon dioxide laser and less than 0.1-as duration with currents up to 1 MA when employing a neodymium laser. Beam focusing in transverse directions is also studied using a model. Possible applications of such electron bunches are reviewed, including obtaining attosecond pulses of tunable coherent radiation in UV and X-ray regions.
* V.A.Papadichev, Proceedings of EPAC08, p.2815.
** V.A.Papadichev, Proceedings of IPAC'10, Kyoto, Japan, p. 4372.
*** V.A.Papadichev, Proc. RUPAC-2010, TUPSAO10, p. 56.

WEPZ010

Modeling and Experimental Update on Direct Laser Acceleration

electron, plasma, acceleration, simulation

2787

I. Jovanovic, M.W. Lin
Penn State University, University Park, Pennsylvania, USA

Funding: This work is supported by the Defense Threat Reduction Agency under contract HDTRA1-11-1-0009.
Moderate-energy, high-repetition-rate electron beams are needed in a variety of applications such as those in security and medicine, while requiring that the acceleration be realized in a compact and relatively inexpensive package. Laser wakefield acceleration is an attractive technology which meets most of those requirements, but it requires the use of relatively high peak power lasers which do not scale readily to high repetition rates. We are developing the theoretical and experimental basis for advancing the science and technology of direct laser acceleration (DLA) of charged particles using the axial component of the electric field of a radially polarized intense laser pulse. DLA is an acceleration method which exhibits no threshold and is thus compatible with the use of lower peak power, but much higher repetition rate lasers. We are currently numerically investigating the conditions for quasi-phase-matched DLA of electrons in plasma waveguides and experimentally implementing the quasi-phase-matched waveguide structure in laser-produced plasmas.

WEPZ011

Fast Cooling of Bunches in Compton Storage Rings

electron, emittance, scattering, photon

2790

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

We propose an enhancement of laser radiative cooling by utilizing laser pulses of small spatial and temporal dimensions, which interact only with a fraction of an electron bunch circulating in a storage ring. We studied the dynamics of such electron bunch when laser photons scatter off the electrons at a collision point placed in a section with nonzero dispersion. In this case of ‘asymmetric cooling', the stationary energy spread is much smaller than under conditions of regular scattering where the laser spot size is larger than the electron beam; and the synchrotron oscillations are damped faster. Coherent oscillations of large amplitude may be damped within one synchrotron period, so that this method can support the rapid successive injection of many bunches in longitudinal phase space for stacking purposes. Results of extensive simulations are presented for the performance optimization of Compton gamma-ray sources and damping rings.

WEPZ016

Generation and Characterization of Electron Bunches with Ramped Current Profiles at the FLASH Facility

electron, wakefield, linac, free-electron-laser

2805

P. Piot
Fermilab, Batavia, USA
C. Behrens, C. Gerth, M. Vogt
DESY, Hamburg, Germany
F. Lemery, D. Mihalcea
Northern Illinois University, DeKalb, Illinois, USA

Funding: This work was supported the Defense Threat Reduction Agency, Basic Research Award # HDTRA1-10^-1-0051, to Northern Illinois University and the German's Bundesministerium f\"ur Bildung und Forschung
We report on the successful generation of electron bunches with current profiles that have a quasi-linear dependency on the longitudinal coordinate. The technique relies on impressing nonlinear correlations in the longitudinal phase space using a linac operating at two frequencies (1.3 and 3.9 GHz) and a bunch compressor. Data taken for various accelerator settings demonstrate the versatility of the method. The produced bunches have parameters well matched to drive high-gradient accelerating field with enhanced transformer ratio in beam-driven accelerators based on sub-mm-sizes dielectric or plasma structures.

WEPZ021

Self-Consistent Dynamics of Electromagnetic Pulses and Wakefields in Laser-Plasma Interactions

plasma, wakefield, simulation, space-charge

2811

A. Bonatto, R. Pakter, F.B. Rizzato
IF-UFRGS, Porto Alegre, Brazil

In the present work we study the stability of laser pulses propagating in a cold relativistic plasma, which can be of interest for particle acceleration schemes. After obtaining a Lagrangian density from the one-dimensional equations for the laser pulse envelope and the plasma electron density, we define a trial function and apply the variational approach in order to obtain an analytical model which allows us to calculate an effective potential for the pulse width. Using this procedure, we analyze the stability of narrow and large laser pulses and then compare its results with numerical solutions for the envelope and density equations.

WEPZ025

Study of Self-injection of an Electron Beam in a Laser-driven Plasma Cavity

electron, plasma, simulation, injection

2820

S. Krishnagopal, S.A. Samant, D. Sarkar
BARC, Mumbai, India
P. Jha
Lucknow University, Lucknow, India
A.K. Upadhyay
CBS, Mumbai, India

Over the last few years, remarkable advances in laser wakefield acceleration of electrons have been achieved, including quasi-monoenergetic beams and GeV energy in a few centimeters. However, it is necessary to achieve good beam quality (large current, low energy-spread and low emittance) for applications such as free-electron lasers. We study self-injection in two regimes of the laser-plasma interaction: the moderate intensity, self-guiding regime, and the low intensity, near-injection-threshold regime, both in a homogeneous plasma that completely fills the simulation volume. We find good beam quality with injection of on-axis electrons, especially at lower intensity. We also study the case when the laser has to travel through vacuum before entering the plasma. We find that injection here is completely different, from off-axis electrons, and the beam quality is poorer.

WEPZ027

Stabilization of the LWFA and its Application to the Single-shot K-edge Densitometry

electron, scattering, emittance, wakefield

2823

K. Koyama, H. Madokoro, Y. Matsumura
University of Tokyo, Tokyo, Japan
R. Kuroda, K. Yamada
AIST, Tsukuba, Ibaraki, Japan
H. Masuda, M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
S. Masuda
Osaka University, Suita, Osaka, Japan

Funding: This work was supported in part by Global COE Program “Nuclear Education and Research Initiative,” MEXT, Japan
Injection of electrons into a laser wakefield accelerator (LWFA) via a wavebreaking process was investigated in order to obtain stable output of electron bunches. A density down ramp for occurring the wavebreaking was formed by an oblique shockwave, which was excited by setting a little flow-deflector on an edge of the supersonic nozzle of high-Mach number (M=5). Parameters of the jet were examined by using PIC code and evaluated by using an interferometer, the density was 10¹⁹cm^-3, density ratio was 2, and the characteristic length was 70 microns. Injection experiments using 7-TW laser pulses suggested that electrons were injected in the density ramp. Since the all-optical Compton X-ray is attractive source for an accurate densitometry, a preliminary experiment of a single-shot K-edge densitometry was performed by using X-ray pulses generated by the laser-Compton scattering (LCS) device based on a compact S-band 40 MeV linac at AIST. The single-shot K-edge densitometry was also applicable to evaluate the transverse emittance of electron bunches.

WEPZ030

Study on a Gas-filled Capillary Waveguide for Laser Wakefield Acceleration

simulation, acceleration, electron, plasma

2829

M.S. Kim, D. Jang, D. Jang, H. Suk
APRI-GIST, Gwangju, Republic of Korea

In gas-filled capillary waveguide for lase wakefield accelerators the gas flows through the two gas feed lines used to sustain constant pressure. Compared to the supersonic gas-jet system operated under high pressure, the gas at low pressure (<1atm) is injected inside capillary waveguide, so that this waveguide has experimental limit to the measurement of the neutral density. In order to investigate the gas pressure in capillary system we used computational fluid dynamics (CFD) simulation. In this paper, we presented the gas pressure changed by a variety of parameters, such as length and sizes of gas feed lines, and the method to decrease the turbulence effect at the ends of capillary.

WEPZ031

Accelerator Studies on a Possible Experiment on Proton-driven Plasma Wakefields at CERN

plasma, proton, electron, acceleration

2832

R.W. Assmann, I. Efthymiopoulos, S.D. Fartoukh, G. Geschonke, B. Goddard, C. Heßler, S. Hillenbrand, M. Meddahi, S. Roesler, F. Zimmermann
CERN, Geneva, Switzerland
A. Caldwell, G.X. Xia
MPI-P, München, Germany
P. Muggli
MPI, Muenchen, Germany

There has been a proposal by Caldwell et al to use proton beams as drivers for high energy linear colliders. An experimental test with CERN's proton beams is being studied. Such a test requires a transfer line for transporting the beam to the experiment, a focusing section for beam delivery into the plasma, the plasma cell and a downstream beam section for measuring the effects from the plasma and safe disposal of the beam. The work done at CERN towards the conceptual layout and design of such a test area is presented. A possible development of such a test area into a CERN test facility for high-gradient acceleration experiments is discussed.

WEPZ034

Double Resosnant Plasma Wakefields

plasma, simulation, wakefield, electron

2838

B.D. O'Shea, A. Fukasawa, B. Hidding, J.B. Rosenzweig, S. Tochitsky
UCLA, Los Angeles, California, USA
D.L. Bruhwiler
Tech-X, Boulder, Colorado, USA

Present work in Laser Plasma Accelerators focuses on a single laser pulse driving a non-linear wake in a plasma. Such single pulse regimes require ever increasing laser power in order to excite ever increasing wake amplitudes. Such high intensity pulses can be limited by instabilities as well engineering restrictions and experimental constraints on optics. Alternatively we present a look at resonantly driving plasmas using a laser pulse train. In particular we compare analytic, numerical and VORPAL simulation results to characterize a proposed experiment to measure the wake resonantly driven by four Gaussian laser pulses. The current progress depicts the interaction of 4 CO2 laser pulses, λlaser = 10.6μm, of 3 ps full width at half max- imum (FWHM) length separated peak-to-peak by 18 ps, each of normalized vector potential a0 ≃ 0.7. Results con- firm previous discourse (*,**) and show, for a given laser pro- file, an accelerating field on the order of 900 MV/m, for a plasma satisfying the resonant condition, ωp=π/t_fwhm.
* Umstadter, D., et al, Phys. Rev. Lett. 72, 1224
** Umstadter, D., et al, Phys. Rev. E 51, 3484

THYB01

Advanced Beam Manipulation Techniques at SPARC

gun, emittance, linac, simulation

2877

A. Mostacci, D. Alesini, P. Antici, A. Bacci, M. Bellaveglia, R. Boni, M. Castellano, E. Chiadroni, G. Di Pirro, A. Drago, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, E. Pace, A.R. Rossi, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
B. Marchetti
INFN-Roma II, Roma, Italy
M. Migliorati
University of Rome "La Sapienza", Rome, Italy
L. Palumbo
Rome University La Sapienza, Roma, Italy
V. Petrillo, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma), Italy

SPARC in Frascati is a high brightness photo-injector used to drive Free Electron Laser experiments and explore advanced beam manipulation techniques. The R&D effort made for the optimization of the beam parameters will be presented here, together with the major experimental results achieved. In particular, we will focus on the generation of sub-picosecond, high brightness electron bunch trains via velocity bunching technique (the so called comb beam). Such bunch trains can be used to drive tunable and narrow band THz sources, FELs and plasma wake field accelerators.

Slides THYB01 [20.772 MB]

THPC007

Laser Electron Interaction Simulation for the Femtosecond Bunch Slicing on SOLEIL Storage Ring

electron, wiggler, simulation, storage-ring

2918

J.F. Zhang, M.-E. Couprie, M. Labat, A. Loulergue, A. Nadji
SOLEIL, Gif-sur-Yvette, France

The interaction of an electron bunch and a laser in a wiggler (modulator) to generate a femtosecond slice is simulated for the slicing project on SOLEIL storage ring, using a code based on Monte-Carlo method and GENESIS. The results from these two codes are consistent with the theoretical values. The maximum modulated energy of the electron bunch and the number of electrons above a certain limit are studied for different wiggler and laser parameters. The transport of the 6D distribution of the sliced bunch from the modulator to the radiators are simulated using AT (Accelerator Toolbox) and ELEGANT, with synchrotron radiation on and taking into account the collective effects of the sliced bunch core.

THPC015

A Dedicated THz Beamline at DELTA

electron, radiation, simulation, undulator

2939

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

Funding: Work supported by DFG, BMBF, and by the Federal State NRW
As a consequence of the new radiation source for ultrashort VUV pulses at DELTA, which is based on the interaction of electrons with fs laser pulses, coherent THz radiation is emitted. Simulations of the laser-electron interaction, particle dynamics and radiation spectrum, as well as the optical and mechanical design of a dedicated THz beamline are presented. First experimental results including laser-electron overlap diagnostics and characterization of the THz radiation are discussed.

THPC016

Ultrashort VUV and THz Pulse Generation at the DELTA Storage Ring

electron, undulator, radiation, klystron

2942

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

Funding: Supported by DFG, BMBF, and the Federal State NRW
The optical klystron (two undulators, separated by a dispersive section) at DELTA, formerly operated as storage-ring FEL, is seeded with ultrashort pulses from a Ti:Sapphire laser. The thus induced energy modulation of an electron bunch in the first undulator is converted to a density modulation within the dispersive chicane. In the second undulator, the micro-bunched electrons emit ultrashort pulses coherently at harmonics of the fundamental laser wavelength. Additionally, coherent ultrashort THz pulses are generated several meters downstream of the optical klystron by the laser-induced gap in the electron bunch. First results are presented.

THPC017

Temporal and Spatial Alignment of Electron Bunches and Ultrashort Laser Pulses for the CHG Experiment at DELTA

electron, undulator, controls, synchrotron

2945

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

Funding: Supported by DFG, BMBF, and the Federal State NRW
The generation of ultrashort VUV pulses by CHG (Coherent Harmonic Generation) requires achieving and maintaining the longitudinal and transversal overlap of femtosecond laser pulses and electron bunches. We present the techniques and the experimental setup applied at the DELTA storage ring. For the longitudinal analysis, both a streak camera and a fast photo diode are used. Transversely, two CCD cameras acquire images of laser and synchrotron light at different positions inside of the undulator. A feedback system utilizes the intensity of a THz signal generated several meters downstream of the undulator to optimize and maintain the overlap.

THPC042

Status and Development of the SAGA Light Source

storage-ring, controls, undulator, linac

2996

T. Kaneyasu, Y. Iwasaki, S. Koda, Y. Takabayashi
SAGA, Tosu, Japan

The SAGA Light Source (SAGA-LS) is a synchrotron radiation facility consisting of a 255 MeV injector linac and a 1.4 GeV storage ring, and has been stably providing synchrotron light since 2006. The annual failure time is less than 1% of the user time in the recent two years. Three insertion devices are installed in the storage ring: an APPLE-II undulator, a planar type undulator (Saga Univ.) and a 4 T superconducting wiggler (SCW). The SCW contains a hybrid three-pole magnet; the main pole of the magnet is surrounded by superconducting coils while side poles are normal conducting magnets. The main pole of the SCW is cooled by a GM cryocooler, which allows the SCW be operated without liquid helium. Since the installation in March 2010, the SCW has been operated stably. To control the ID parameters during the user time, a feed-forward correction system which minimizes the ID effects on the emittance coupling was developed. The laser Compton Gamma-rays were generated by using a CO2 laser and were used for beam energy measurement. In addition, research works on the beam lifetime and interaction between electron beam and crystal, and development of a multipole magnet are in progress.

THPC053

Shanghai Soft X-Ray Free Electron Laser Test Facility

radiation, linac, FEL, electron

3011

Z.T. Zhao
SINAP, Shanghai, People's Republic of China

As a critical development step towards constructing a hard X-ray FEL in China, a soft X-ray FEL test facility (SXFEL) was proposed and will be constructed at the SSRF campus by a joint team of Institute of Tsinghua University and Shanghai Institute of Applied Physics. This test facility, based on an 840MeV electron linear accelerator, aims at generating 9nm FEL radiation with two-stage cascaded HGHG scheme. The project proposal was approved in February 2011 by central government, and the constrction is expected to start in early 2012. This paper describes the preliminary design of this soft X-ray test facility and the R&D progress of the key FEL technologies in the SDUV-FEL test bench.

THPC079

Echo-enabled Harmonic Generation at DELTA

undulator, electron, bunching, storage-ring

3074

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

Funding: Supported by DFG, BMBF, and the Federal State NRW
We present conceptual studies of the realization of the echo-enabled harmonic generation (EEHG) technique proposed by G. Stupakov* as an upgrade of the present coherent harmonic generation (CHG) project at the DELTA storage ring**. EEHG allows to reach shorter wavelengths compared to the CHG scheme. In addition to the optical klystron used for CHG, a third undulator is needed for a second energy modulation of the electron bunch, followed by an additional strong dispersive section. Installing these insertion devices requires a new long straight section in the storage ring and a new lattice configuration.
* G. Stupakov Phys. Rev. Lett. 10², 074801 (2009)
** A. Schick et al., this conference

THPC081

Status of the Free-Electron Laser FLASH at DESY

FEL, undulator, photon, radiation

3080

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

The free-electron laser facility FLASH at DESY, Germany has been upgraded in 2010. Now, FLASH delivers an electron beam energy up to 1.25 GeV. The longitudinal phase-space is linearized by 3.9 GHz superconducting cavities. The facility delivers to users ultra-short laser like radiation pulses in the range of less than 50 fs to 200 fs in the soft X-ray wavelenth range from 44 down to 4.1 nm. FLASH provides hundreds to thousands pulses per second to users with unprecedented peak brilliance. FLASH will be upgraded with a second undulator beam line and an additional experimental hall. Construction starts Autumn 2011. We summarize the operational status of the ongoing 3rd user period.

THPC083

Analysis of Parameter Space of a Kilowatt-scale Free Electron Laser for Extreme Ultraviolet Lithography Driven by L-band Superconducting Linear Accelerator Operating in a Burst Mode

electron, radiation, FEL, undulator

3086

E. Schneidmiller, V. Vogel, H. Weise, M.V. Yurkov
DESY, Hamburg, Germany

The driving engine of the Free Electron Laser in Hamburg (FLASH) is an L-band superconducting accelerator. It is designed to operate in a burst mode with 800 microsecond pulse duration at a repetition rate of 10 Hz. The maximum accelerated beam current during the macropulse is 10 mA. In this paper we analyze the parameter space for optimum operation of the FEL at the wavelength of 13.5 nm and 6.7 nm. Our analysis shows that the FLASH technology holds great potential for increasing the average power of the linear accelerator and an increase of the conversion efficiency of the electron kinetic energy to the light. Thus, it will be possible to construct a FLASH like free electron laser with an average power up to 3 kW. Such a source meets the requirements of the light source for the next generation lithography.

THPC087

Saturation Effect on VUV Coherent Harmonic Generation at UVSOR-II

electron, simulation, FEL, bunching

3098

T. Tanikawa, M. Adachi, M. Katoh, J. Yamazaki, H. Zen
UVSOR, Okazaki, Japan
M. Hosaka, Y. Taira, N. Yamamoto
Nagoya University, Nagoya, Japan

Light source technologies based on laser seeding are under development at the UVSOR-II electron storage ring. In the past experiments, we have succeeded in generating coherent harmonics (CHs) in deep ultraviolet (UV) and vacuum UV (VUV) region and also in generating CH with variable polarizations in deep UV*. In previous conference, we reported an introduction of new-constructed spectrometer for VUV and results of spectra measurement, undulator gap dependence, and injection laser power dependence on VUV CHs**. This time we have successfully observed saturation on CHs intensities　and have found some interesting phenomena in different harmonic orders. In this conference, we will discuss the results of some systematic measurements and those analytical and particle tracking simulations***.
*M. Labat et al., Phys. Rev. Lett. 10¹ (2008) 164803.
**T. Tanikawa et al., Proc. IPAC'10, TUPE029, p. 2206 (2010).
***T. Tanikawa et al., Appl. Phys. Express 3 (2010) 122702.

THPC093

Beam Dynamics Simulations for the SwissFEL Injector Test facility

emittance, solenoid, simulation, gun

3107

S. Bettoni, M. Pedrozzi, S. Reiche, T. Schietinger
PSI, Villigen, Switzerland

The SwissFEL under study at PSI will produce 0.1 nm to 0.7 nm wavelength coherent x-ray. The design of the injector is based on the invariant envelope matching scheme, developed for other photoinjectors in the past years. According to this technique the emittance at the exit of the injector can be minimized if some conditions at the entrance of the booster are satisfied. A campaign of simulations has been carried out to verify the impact of the errors of the machine components (RF and magnetic) and laser shaping (transverse and longitudinal) on the final SwissFEL injector emittance. These results have to be used to define the tolerances on the machine and laser.

THPC095

Commissioning Status of the SwissFEL Injector Test Facility

emittance, solenoid, gun, electron

3110

T. Schietinger, M. Aiba, S. Bettoni, B. Beutner, A. Falone, R. Ganter, R. Ischebeck, F. Le Pimpec, N. Milas, G.L. Orlandi, M. Pedrozzi, E. Prat, S. Reiche, C. Vicario
PSI, Villigen, Switzerland

The SwissFEL injector test facility at the Paul Scherrer Institute has been in operation since August 2010. Its primary goal is the demonstration of a high-brightness electron beam as it will be required to drive the SwissFEL main linac. The injector further serves as a platform for the development and validation of accelerator components needed for the SwissFEL project. We give an overview of recent commissioning activities at about 130 MeV beam energy, with particular emphasis on results from optics matching studies and emittance measurements, the latter obtained with different optics-based methods. A five-cell transverse-deflecting cavity allows studies of the longitudinal bunch charge distribution and slice emittance. Bunch length measurements will become the focus of interest after the installation of a magnetic compression chicane, currently scheduled for the summer of 2011.

THPC096

Soft X-ray Free-electron Laser with a 10-time Reduced Size

electron, undulator, FEL, bunching

3113

Y.-C. Huang, F.H. Chao, C.H. Chen, K.Y. Huang
NTHU, Hsinchu, Taiwan
P.J. Chou
NSRRC, Hsinchu, Taiwan

Funding: This work is supported by National Science Council under Contract NSC 99-2112-M-007 -013 -MY3.
We present a 30-m long soft x-ray FEL consisting of a 5-MeV photoinjector, a 150 MeV linac, a magnetic chicane compressor, and a 3-m long undulator. We employ both the 3rd and the 4th harmoincs of a Nd laser at 355 and 266 nm, respectively, to illuminate the cathode of the photoinjector. Owing to the beating of the two lasers, the emitted electron beam is modulated at 282 THz. The electrons are further accelerated to 150 MeV and, after acceleration, compressed by 33 times in a magnetic chicane. The temporal compression of the electron macropulse increases the electron bunching frequency to 9.3 PHz, corresponding to a soft x-ray wavelength of 32.2 nm. We adopt a solenoid-derived staggered array undulator* with a 3-m length, 5 mm undulator period, and 1.2 mm gap. With a solenoid field of 10 kG, we estimate an undulator parameter of 0.4 and a corresponding radiation wavelength of 32.2 nm for a 150 MeV driving beam. With 3.3-kA peak current, 0.03% energy spread, 2 mm-mrad emittance, and 80-micron beam radius at the undulator entrance, the GENESIS code predicts 0.2 GW radiation power from the 3-m long undulator for an initial bunching factor of merely 10 ppm.
* Y.C. Huang, H.C. Wang, R.H. Pantell, and J. Feinstein, "A staggered-array wiggler for far infrared, free-electron laser operation," IEEE J. Quantum Electronics 30 (1994) 1289.

THPC097

Transverse Alignment Tolerances for the European XFEL Laser Heater

electron, FEL, undulator, emittance

3116

V.A. Goryashko
NASU/IRE, Kharkov, Ukraine
M. Dohlus
DESY, Hamburg, Germany
M. Hamberg, V.G. Ziemann
Uppsala University, Uppsala, Sweden

Funding: Supported by the KTH-SU-UU FEL Center.
We study the impact of misalignments between a laser beam and an electron bunch on the energy distribution function of the electron bunch in the laser heater. Transverse position and angular misalignment as well as different spot size of the laser and electron beam are considered. We find that the transverse misalignment makes the energy distribution function narrower compared to the case of ideal adjustment and a distinct peak in the distribution around the initial mean value of the energy appears. We demonstrate that despite these misalignments a uniform heating in terms of the energy spread can be achieved by appropriately adapting the transverse size and power of the laser beam such that the energy distribution function of the electron bunch at the end of the laser heater can be made similar to a Gaussian, thus providing more effective Landau damping against the micro-bunching instability. The laser power mainly determines the local energy spread while the laser spot size governs the shape of the energy distribution function. The transverse oscillations of electrons induced by the magnetic field in the laser heater are found to be non-essential for typical operation parameters.

THPC100

Full Temporal Reconstruction using an Advanced Longitudinal Diagnostic at the SPARC FEL

FEL, diagnostics, radiation, undulator

3119

G. Marcus, J.B. Rosenzweig
UCLA, Los Angeles, California, USA
M. Artioli, F. Ciocci, L. Giannessi, A. Petralia, M. Quattromini, V. Surrenti
ENEA C.R. Frascati, Frascati (Roma), Italy
A. Bacci, M. Bellaveglia, E. Chiadroni, G. Di Pirro, M. Ferrario, G. Gatti, A. Mostacci, A.R. Rossi
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
INFN-Roma II, Roma, Italy
V. Petrillo
Istituto Nazionale di Fisica Nucleare, Milano, Italy
J.V. Rau
ISM-CNR, Rome, Italy

The Production of ultra-short (sub 100 fs) single-spike radiation possessing full longitudinal coherence from a free-electron laser (FEL) has been the subject of intense study. A Frequency-Resolved Optical Gating (FROG) diagnostic has been developed and tested at UCLA, which has the capability of providing a longitudinal reconstruction of these ultra-fast pulses. This paper reports the results of the application of the diagnostic at the SPARC FEL facility.

THPC104

Optimization for Single-Spike X-Ray Fels at LCLS with a Low Charge Beam

undulator, FEL, simulation, electron

3131

L. Wang, Y.T. Ding, Z. Huang
SLAC, Menlo Park, California, USA

The recently commissioned Linac Coherent Light Source is an x-ray free-electron laser at the SLAC National Accelerator Laboratory, which is now operating at x-ray wavelengths of 20-1.2 Angstrom with peak brightness nearly ten orders of magnitude beyond conventional synchrotron sources. At the low charge operation mode (20 pC), the x-ray pulse length can be <10 fs. In this paper we report our numerical optimization and simulations to produce even shorter x-ray pulses by optimizing the machine and undulator setup. In the soft x-ray regime, with the help of slotted-foil or undulator taper, a single spike x-ray pulse is achievable with peak FEL power of 30 GW.

THPC109

First Demonstration of Electron Beam Generation and Characterization with an All Superconducting Radio-frequency (SRF) Photoinjector*

cavity, SRF, cathode, solenoid

3143

T. Kamps, W. Anders, R. Barday, A. Jankowiak, J. Knobloch, O. Kugeler, A.N. Matveenko, A. Neumann, T. Quast, J. Rudolph, S.G. Schubert, J. Völker
HZB, Berlin, Germany
P. Kneisel
JLAB, Newport News, Virginia, USA
R. Nietubyc
The Andrzej Soltan Institute for Nuclear Studies, Centre Swierk, Swierk/Otwock, Poland
J.K. Sekutowicz
DESY, Hamburg, Germany
J. Smedley
BNL, Upton, Long Island, New York, USA
V. Volkov
BINP SB RAS, Novosibirsk, Russia
G. Weinberg
FHI, Berlin, Germany
I. Will
MBI, Berlin, Germany

Funding: Work supported by Bundesministerium für Bildung und Forschung und Land Berlin. The work on the Pb cathode film is supported by EuCARD Grant Agreement No. 227579
In preparation for a high brightness, high average current electron source for the energy-recovery linac BERLinPro an all superconducting radio-frequency photoinjector is now in operation at Helmholtz-Zentrum Berlin. The aim of this experiment is beam demonstration with a high brightness electron source able to generate sub-ps pulse length electron bunches from a superconducting (SC) cathode film made of Pb coated on the backwall of a Nb SRF cavity. This paper describes the setup of the experiment and first results from beam measurements.

THPC111

Operation of an L-band RF Gun with Pulses Inside the Burst Mode RF Pulse

gun, cavity, klystron, controls

3146

V. Vogel, V. Ayvazyan, B. Faatz, K. Flöttmann, D. Lipka, P. Morozov, H. Schlarb, S. Schreiber
DESY, Hamburg, Germany

The Free-Electron Laser in Hamburg (FLASH) is a user facility since 2005, delivering femtosecond short radiation pulses in the wavelength range between 4.1 and 44 nm using the SASE principle. In FLASH, the electron beam is accelerated to 1.25 GeV with L-band superconducting cavities. The electron source is a normal conducting RF-gun photoinjector. The L-band standing wave RF gun has one and a half cells. The gun is operated in burst mode with an RF pulse length of up to 900 microseconds and a repetition rate of 10 Hz. Several hundreds to thousands of bunches are accelerated per second. With 5 MW of pulsed forward power, the dissipated power inside the RF gun is 45 kW. In this paper we propose an operational mode which allows us to reduce the dissipated power to ease operation or to increase the effective duty cycle in the gun by pulsing the gun within one burst. We report on first experimental results at FLASH, where an RF burst of 46μRF-pulses with a length of 10 microseconds separated by 10 microseconds has been successfully generated reducing the dissipated power by a factor of 2.

THPC113

Slice Emittance Measurements for Different Bunch Charges at PITZ

emittance, solenoid, electron, booster

3149

Ye. Ivanisenko, H.-J. Grabosch, M. Gross, L. Hakobyan, G. Klemz, M. Krasilnikov, M. Mahgoub, D. Malyutin, A. Oppelt, M. Otevřel, B. Petrosyan, D. Richter, S. Rimjaem, A. Shapovalov, F. Stephan, G. Vashchenko, S. Weidinger
DESY Zeuthen, Zeuthen, Germany
G. Asova
INRNE, Sofia, Bulgaria
I.I. Isaev
MEPhI, Moscow, Russia
M.A. Khojoyan
YerPhI, Yerevan, Armenia
I.H. Templin, I. Will
MBI, Berlin, Germany

The successful operation of the Free electron LASer in Hamburg (FLASH) at DESY brings up the interest in further broadening the spectrum of possible applications also for the upcoming European XFEL. Hence the electron beam properties required for lasing should be tested and optimized for a broad range of values already on the level of the injector. The Photo Injector Test facility in Zeuthen (PITZ) at DESY characterizes the photo injectors for FLASH and the European XFEL. The main study involves the transverse projected emittance optimization for different beam conditions. Beside the projected emittance, the PITZ setup allows to measure the transverse emittance with a sub-bunch longitudinal resolution. This slice emittance diagnostics is based on the usage of bunches with an energy correlation of the longitudinal phase space components induced by the booster. Then the bunch is swept vertically with a dipole magnet. Part of the bunch that corresponds to a longitudinal slice is cut out by means of a vertical slit and the horizontal emittance is measured. This report presents the results of recent slice emittance measurements for different bunch charges.

THPC114

High Brightness Photo Injector Upgrade and Experimental Optimization at PITZ

emittance, electron, gun, booster

3152

M. Krasilnikov, H.-J. Grabosch, M. Gross, Ye. Ivanisenko, G. Klemz, W. Köhler, M. Mahgoub, D. Malyutin, A. Oppelt, M. Otevřel, B. Petrosyan, S. Rimjaem, F. Stephan, G. Vashchenko, S. Weidinger, R.W. Wenndorff
DESY Zeuthen, Zeuthen, Germany
G. Asova
INRNE, Sofia, Bulgaria
L. Hakobyan, M.A. Khojoyan
YerPhI, Yerevan, Armenia
M. Hoffmann, H. Schlarb
DESY, Hamburg, Germany
I.I. Isaev, A. Shapovalov
MEPhI, Moscow, Russia
M.A. Nozdrin
JINR, Dubna, Moscow Region, Russia
D. Richter
HZB, Berlin, Germany
I.H. Templin, I. Will
MBI, Berlin, Germany

The photo injector test facility at DESY in Zeuthen (PITZ) develops and optimizes electron sources for linac driven free electron lasers. The main goal of PITZ is to demonstrate a small electron beam emittance by tuning several main parameters of the injector - photo cathode laser pulse, rf gun with solenoids and booster cavity parameters. A slit scan technique is used to measure the transverse phase space of the electron beam and the projected normalized emittance. The photo injector is capable of pulse train production which can be measured with dedicated diagnostics at PITZ. This enables optimization of the beam emittance for a wide range of bunch charges from tens of pC to several nC while keeping high resolution of beam measurements. The results of the experimental optimization will be presented yielding a new benchmark of photo injector performance.

THPC115

Emittance Optimization for Different Bunch Charges with Upgraded Setup at PITZ

emittance, gun, booster, electron

3155

G. Vashchenko, G. Asova, M. Gross, L. Hakobyan, I.I. Isaev, Ye. Ivanisenko, M.A. Khojoyan, M. Krasilnikov, M. Mahgoub, D. Malyutin, M. Otevřel, B. Petrosyan, S. Rimjaem, A. Shapovalov, F. Stephan, S. Weidinger
DESY Zeuthen, Zeuthen, Germany
M.A. Nozdrin
JINR, Dubna, Moscow Region, Russia
D. Richter
HZB, Berlin, Germany
I.H. Templin, I. Will
MBI, Berlin, Germany

The Photo Injector Test facility at DESY, Zeuthen site, (PITZ) has the aim to develop and optimize high brightness electron sources for Free Electron Lasers like FLASH and the European XFEL. Photo electrons emitted from the Cs2Te cathode are accelerated by a 1.6-cell L-band RF gun cavity operated at 60 MV/m maximum accelerating gradient at the cathode. Cylindrically shaped laser pulses with a flat-top temporal profile of about 20 ps FWHM and 2 ps rise and fall time are used to produce electron beams with extremely low emittance. The PITZ beam line was upgraded in 2010. The new gun cavity (prototype number 4.1) was installed January 2010. The new booster cavity (CDS) with well-defined field distribution was installed in July 2010. The diagnostic system for characterization of the laser hitting the photocathode was upgraded in October 2010. Emittance measurements results for different charges: 2 nC, 1 nC, 0.25 nC, 0.1 nC and 0.02 nC, will be presented. The optimization was done for different parameters, e.g. gun solenoid current, gun phase, laser spot size on the cathode, booster gradient.

THPC118

Present Status of Quantum Radiation Sources on the Basis of the S-band Compact Electron Linac

electron, radiation, cavity, linac

3164

R. Kuroda, E. Miura, H. Toyokawa, K. Yamada, E. Yamaguchi
AIST, Tsukuba, Ibaraki, Japan
M. Kumaki
RISE, Tokyo, Japan

We have developed quantum radiation sources such as a laser Compton scattering (LCS) X-ray and a coherent THz radiation sources on the basis of the S-band compact electron linac at AIST in Japan. The S-band linac consists of the laser-driven photocathode rf gun and two 1.5 m-long acceleration tubes and can accelerate the electron beam up to about 42 MeV. The LCS X-ray source can generate a quasi-monochromatic hard X-ray with variable energy of 12 - 40 keV for medical and biological applications. Now, the multi-collision LCS system has been developed with the regenerative amplifier type laser storage cavity and the multi-bunch electron beam to increase the X-ray yield. On the other hand, the high-power coherent THz radiation source has been also developed and its peak power is estimated to be more than 1 kW in frequency range between 0.1 - 2 THz. The high-power THz radiation was applied to the scanning transmission imaging. Now, the high power THz time domain spectroscopy (TDS) has been developed for the material science. In this conference, we will report the present status of the S-band compact electron linac, our quantum radiation sources and applications.

THPC120

Experimental Investigation of Photocathode Thermal Emittance Components with a Copper Cathode*

emittance, cathode, gun, electron

3167

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

With progress of photocathode RF gun technology, thermal emittance has become the primary limitation of electron beam brightness*. Extensive efforts have been devoted to study thermal emittance, but experiment results diverge between research groups and few can be well interpreted**. One possibility is the undefined online cathode surface conditions, which may cause difference of work functions, field enhancement factor and surface roughness, and lead to thermal emittance divergence. In this paper, we report an experiment of characterizing online photocathode work function, field enhancement factor and surface roughness effect by measuring electric field dependence of photoemission quantum efficiency (QE) and thermal emittance in a Cu-cathode RF gun. Preliminary experiment results reveal huge thermal emittance contributed by surface roughness for the first time, and are in reasonable consistency with theoretical model prediction***.
*Ivan V. Bazarov et al., Phys. Rev. Lett. 10², 104801(2009)
** D.H. Dowell et al, Nucl. Instrum. Methods Phys. Res., Sect. A 622, 685 (2010).
***D. Xinag et al, PAC’07, 10⁴⁹ (2007)

THPC126

RF Gun Studies for the SwissFEL Injector

gun, emittance, solenoid, cathode

3179

A. Falone, A. Adelmann, J.-Y. Raguin, L. Stingelin
PSI, Villigen, Switzerland

The Paul Scherrer Institut (PSI) is planning a compact, high brightness hard X-ray free electron laser. For this purpose a new 2.5 cell RF gun has been designed at PSI and is now in production. The RF gun plays an important role in preserving beam emittance, and hence delivers a high quality beam to the injector. We present beam dynamic parametric studies on the effect of cell length variations using two different codes OPAL and ASTRA. Furthermore laser and other RF parameters are scanned to find the best working point of the injector. The simulations are showing that the SwissFEL injector requirements (ϵ<0.4 mm mrad normalized projected emittance) are achievable with a smooth dependence on the geometrical variation of the gun cell lengths confirming a robust RF design of the gun is possible.

THPC127

Recent Results from a Combined Diode-RF Gun

emittance, cathode, electron, gun

3182

C.H. Gough, S. Ivkovic, M. Paraliev
PSI, Villigen, Switzerland

For the SwissFEL project, a novel combined diode-RF electron gun was tested at PSI, as a possible source for XFELs. Typically, electron bunches of 1-100 pC charge , 1-5 MeV energy and 2-0.3 um-rad emittance were produced and measured. The advantage of the combined gun is that diode geometry and emission surface can be changed readily. An optimum polishing procedure for magnesium photo cathodes was found, and various surfaces such as FEA's were tested in high gradient. Emittance changes for emission surface depression within the cathode, as well as laser spot size and anode hole size, were measured. Finally, the excellent performance of the gun permitted detailed study of the pepperpot EMSY (Emittance Measurement System) behaviour with changing beam parameters.

THPC129

Gallium Arsenide Photocathode Research at Daresbury Laboratory

cathode, electron, vacuum, gun

3185

L.B. Jones, B.D. Fell, J.W. McKenzie, K.J. Middleman, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.J. Cash
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom
N. Chanlek
UMAN, Manchester, United Kingdom

Significant effort has been expended over several years by ASTeC to optimise procedures for preparing GaAs photocathodes for use as high-current electron sources in accelerators. Having established robust chemical and thermal cleaning processes, and carried out lifetime studies on activated photocathodes by deliberately poisoning them*, we present data showing high levels of Quantum Efficiency (QE) for heterostructure photocathodes when activated with Cs-O and Cs-NF3 procedures. We will show that the use of NF3 delivers higher QE, and conveys greater control in that the final QE level can be set more accurately using NF3 than with O. We plan to carry out further experiments on GaAs photocathodes to measure the 2-D energy distribution of the emitted electrons at both room and cryogenic temperatures. We are constructing a retarding-field electron calorimeter which will measure current as a function of retarding voltage. From this, we will establish the 2-D energy distribution in the electron beam, permitting a comparison of these figures for photocathodes at room and low temperatures. The goal is to create an ultra-bright electron source for use with particle accelerators.
* Proc IPAC ’10, TUPEC018, 1752-1754

THPC130

A 160 keV Photocathode Electron Gun Test Tacility

gun, electron, diagnostics, cathode

3188

L.B. Jones, B.D. Fell, C. Hill, J.W. McKenzie, K.J. Middleman, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
R.J. Cash
STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom

The ALICE ERL* at Daresbury Laboratory is a prototype 4th generation free-electron laser light source operating at IR wavelengths. An upgrade to the DC photoinjector gun has been designed and partially-constructed, but due to installation postponement, the system will be used for photocathode physics experiments. The re-designed gun will operate at 160 keV. The gun and photocathode preparation facility (PPF) will be assembled with a diagnostic beamline, supporting research towards high-brightness electron beams based on GaAs technology. Combining an external PPF with a load-lock facility allows the rapid exchange of photocathodes, thus permitting the testing of various different photocathode heterostructures, and fine control of the cleaning and activation processes applied during preparation. The diagnostics beamline will include a transverse kicker to study bunch length, and a dipole magnet for beam energy and energy spread measurements. Various horizontal and vertical slit and screen assemblies allow for emittance measurement, so providing full 6-D characterisation of the electron bunches generated. A current transformer and Faraday cups support bunch charge measurements.
* Accelerators and Lasers In Combined Experiments electron Energy-Recovery Linac

THPC131

MAX-IV Linac Injector Simulations including Tolerance and Jitter Analysis

linac, gun, emittance, simulation

3191

J.W. McKenzie, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
S. Thorin, S. Werin
MAX-lab, Lund, Sweden

The MAX-IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF) and an FEL (in phase 2). 100 pC bunches of electrons are created from a 1.5 cell S-band photocathode gun and subsequently accelerated up to 3 GeV by S-band linac sections. Simulations of the dynamics of the space-charge dominated beam up to 100 MeV are presented including an analysis of the tolerances required and the effects of jitter sources.

THPC132

A Velocity Bunching Scheme for Creating Sub-picosecond Electron Bunches from an RF Photocathode Gun

cavity, gun, emittance, solenoid

3194

J.W. McKenzie, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Sub-picosecond electron bunches are in demand for various applications including Free Electron Lasers and electron diffraction experiments. Typically, for Free Electron Lasers, a multiple picosecond scale bunch is produced from a photoinjector with compression achieved via one or more magnetic chicanes by providing an appropriate energy chirp to the bunch in the preceding linac sections. This approach is complex, requiring many components, often including a higher harmonic linac section to linearise the longitudinal phase-space, and careful tuning in order to minimise emittance blow-up due to coherent synchrotron radiation. We present a scheme to deliver sub-picosecond electron bunches, based on a normal conducting RF gun and two short linac sections, one for providing velocity bunching and the second to capture the compressed bunch and accelerate to tens of MeV where the beam properties are then essentially frozen.

THPC134

LCLS RF Gun Copper Cathode Performance

cathode, gun, emittance, electron

3200

A. Brachmann, F.-J. Decker, P. Emma, R.H. Iverson, P. Stefan, J.L. Turner, F. Zhou
SLAC, Menlo Park, California, USA

Funding: Work supported by Department of Energy contract DE-AC03-76SF00515
We report on the performance and the operational experience of the LCLS RF gun copper photocathodes used during the LCLS run I, II, III and IV. We discuss the problems of cathode surface contamination and our experience with methods to remove such contamination. Techniques to obtain high quantum efficiency (QE) while preserving the low emittance quality are discussed. Furthermore, we will present the current status of the installed cathode, its quantum efficiency and the typical injector emittances of the extracted beam.

THPC135

Optimal Parameters of the Photocathode Gun Space Charge to Improve Beam Quality

cathode, gun, electron, space-charge

3203

M.G. Fedurin, C. Swinson, V. Yakimenko
BNL, Upton, Long Island, New York, USA

Accelerator Test Facility at Brookhaven National Laboratory operates with 5 MeV photocathode gun and 70 MeV linac for different range of experiments with a few picoseconds and a few micrometers emittance electron bunch. Many conducted experiments require beam with good spatial resolution and short length as well. NdYaG laser pulse turns to the electron bunch in the gun with space charge affecting on the own bunch length and transverse profile. Optimal beam loading parameters of the space charge in the photocathode RF gun could be found and used to improve bunch length and emittance. Simple model and experimental results on the Accelerator Test Facility at Brookhaven national Laboratory will be described

THPC136

High Efficiency Visible Photocathode Development

cathode, synchrotron, vacuum, diagnostics

3206

J. Smedley, K. Mueller, T. Rao
BNL, Upton, Long Island, New York, USA
K. Attenkofer, S.W. Lee
ANL, Argonne, USA
I. Ben-Zvi, X. Liang, E.M. Muller, M. Ruiz-Oses
Stony Brook University, Stony Brook, USA
H.A. Padmore, T. Vecchione
LBNL, Berkeley, California, USA

Alkali antimonide cathodes are critical both for high average current photoinjectors for energy recovery linacs and for high quantum efficiency photodetectors. These cathodes have historically been plagued by extreme vacuum sensitivity, non-reproducibility and poor lifetime. We report on ongoing efforts to improve the performance of alkali antimonides (principally K2CsSb). Cathodes have been fabricated which have a QE of 7% at 532 nm. The films are much more resistant to oxygen and water exposure than previously thought, with a 50% yield lifetime of 20 hrs at 2 pBar partial pressure of water. Several analysis techniques have been employed in this study, including in-situ x-ray diffraction during growth to measure grain size and texture, measurement of transverse momentum distribution of the emitted electrons, and measurement of the stoichiometry of the films via x-ray fluorescence. An extensive study of the growth parameters, including both transparent and metallic substrates, sputtered and evaporated films, variation of growth time and temperatures and post-growth annealing processes, is currently underway.

THPC174

Manufacturing and Testing of the First Phase Shifter Prototypes Built by CIEMAT for the European-XFEL

controls, undulator, electron, free-electron-laser

3308

I. Moya, J. Calero, J.M. Cela-Ruiz, L. García-Tabarés, A. Guirao, J.L. Gutiérrez, L.M. Martinez Fresno, T. Martínez de Alvaro, E. Molina Marinas, A.L. Pardillo, L. Sanchez, S. Sanz, F. Toral, C. Vazquez, J.G.S. de la Gama
CIEMAT, Madrid, Spain

Funding: Work partially supported by the Spanish Ministry of Science and Innovation under SEI Resolution on 17-September-2009.
The European X-ray Free Electron Laser (EXFEL) will be based on a 10 to 17.5 GeV electron linac. Its beam will be used in three undulator systems to obtain ultra-brilliant X-ray flashes from 0.1 to 6 nanometres for experimentation. The undulator systems are formed by 5m long undulator segments and 1.1m long intersections in between. They accommodate a quadrupole on top of a precision mover, a beam position monitor, two air coil correctors and a phase shifter. The function of the phase shifter is to adjust the phase of the electron beam with respect to that of the radiation field when the wavelength is changed by tuning the gap. In this context, CIEMAT will deliver 92 phase shifters, as part of the Spanish in-kind contribution to the EXFEL project. This paper describes the engineering design, the manufacturing techniques and the mechanical and magnetic tests realized on the first prototypes.

THPO025

Longitudinal Beam Dynamics of a Laser Sliced Bunch

synchrotron, electron, radiation, damping

3397

P. Kuske
HZB, Berlin, Germany

Nowadays fs-laser slicing of a bunch of electrons in storage rings is quite common for creating short VUV- and soft X-ray light pulses or pulses of coherently emitted THz-radiation over a couple of revolutions. In this paper the longitudinal dynamics of the sliced bunch is studied numerically. The calculations are based on the one dimensional solution of the Vlasov-Fokker-Planck-equation assuming that the shielded CSR-wake is dominating the dynamics of the 100 fs-long slice. It is found that the density modulation survives longer and that the CSR-spectra extend to higher frequencies at later turns even below the corresponding instability threshold. This very simple model seems to support experimental observations at the Swiss Light Source.

THPS006

Present Status of Beam Cooling and Related Research at S-LSR

electron, proton, ion, betatron

3436

A. Noda, M. Nakao, H. Souda, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
T. Fujimoto, S.I. Iwata, S. Shibuya
AEC, Chiba, Japan
M. Grieser
MPI-K, Heidelberg, Germany
K. Ito, H. Okamoto
HU/AdSM, Higashi-Hiroshima, Japan
K. Jimbo
Kyoto IAE, Kyoto, Japan
K. Noda, T. Shirai
NIRS, Chiba-shi, Japan

Funding: Work supported by Advanced Compact Accelerator Development project of MEXT, and Global COE Program, "The Next Generation of Physics, Spun from Universality and Emergence" at Kyoto University.
With the use of Ion Storage and Cooler Ring, S-LSR at ICR, Kyoto University, Mg ion beam with 40 keV has been laser cooled not only in the longitudinal direction but also in the horizontal direction by "Synchro-Betatron Coupling". Laser cooling is now tried to be extended to vertical direction with horizontal and vertical coupling with the use of a solenoid magnetic field. At S-LSR, an electron beam cooling is also applied for 7MeV proton beam, resulting an ordered state. Electron beam cooling is also applied for rf captured bunched beam and a short pulse proton beam with the duration of ~3 ns is fast extracted in order to enable beam irradiation. A beam course is now being constructed to irradiate bio-molecular cells vertically from the bottom through a thin film separating the accelerator vacuum from the cultivating liquid containing the cells in the air.

THPS012

Simulation of the Generation and Transport of Laser-Accelerated Ion Beams

electron, ion, target, simulation

3445

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

In the framework of the LIGHT project a dedicated test stand is under preparation at GSI for the transport and focusing of laser accelerated ion beams. The relevant acceleration mechanism for the parameters achievable at the GSI PHELIX laser is the TNSA (Target Normal Sheath Acceleration). The subsequent evolution of the ion beam can be described rather well by the isothermal plasma expansion model. This model assumes an initial dense plasma layer with a 'hot' electron component and 'cold' ions. We will present 1D and 2D simulation results obtained with the VORPAL code on the expansion of the beam and on the cooling down of the neutralizing electrons. The electrons and their temperature can play an important role for the focusing of the beam in a solenoid magnet, as foreseen in the GSI test stand. We will discuss possible controlled de-neutralization schemes using external magnet fields.

THPS013

Radiation Pressure Acceleration of Multi-ion Thin Foil

ion, proton, acceleration, target

3448

T.-C. Liu, G. Dudnikova, M.Q. He, C.-S. Liu, R.Z. Sagdeev, X. Shao, J.-J. Su
UMD, College Park, Maryland, USA

Radiation pressure acceleration (RPA) is considered as an efficient way to produce quasi-monoenergetic ions, in which an ultra-thin foil is accelerated by high intensity circularly polarized laser. Our simulation study shows that an important factor limiting this acceleration process is the Rayleigh-Taylor instability, which results in the exponential growth of the foil density perturbation during the acceleration and hence the induced transparency of the foil and broadening of the particle energy spectrum. We will study RPA of multi-ion thin foil made of carbon and hydrogen and investigate the possibility of using abundant electrons supplied from carbon to delay the foil from becoming transparent, enhance the acceleration of protons and therefore improve the energy of quasi-monoenergetic proton beam. We will show the dependence of the energy of quasi-monoenergetic proton and carbon beam on the density and concentration ratio of carbon and hydrogen in the foil as well as foil thickness for RPA.

THPS014

Laser Thin Gas Target Acceleration for Quasi-monoenergetic Proton Generation

ion, target, proton, acceleration

3451

M.Q. He, G. Dudnikova, C.-S. Liu, T.-C. Liu, R.Z. Sagdeev, X. Shao, J.-J. Su
UMD, College Park, Maryland, USA
Z.M. Sheng
Shanghai Jiao Tong University, Shanghai, People's Republic of China

We propose a scheme of laser thin gas target acceleration for quasi-monoenergetic proton generation. The scheme uses gas target of thickness about several laser wavelengths with gas density spatial distribution of Guassian or square of sine shape. We performed Particle-In-Cell simulation using circularly polarized laser of normalized maximum amplitude ~5 and hydrogen gas target of thickness ~5 laser wavelength with peak density three times of the critical density. The simulation demonstrates several key physical processes involved in the laser thin gas target acceleration and the observation of quasi-monoenergetic protons. During the early phase of the laser plasma interaction, electron and ion cavities are observed. A compressed plasma layer is formed. The reflected protons in front of the compressed layer are accelerated and thus a bunch of quasi-monoenergetic protons are obtained. The compressed layer is finally destroyed due to Rayleigh-Taylor instability. The acceleration of the quasi-monoenergetic proton then stops with maximum energy about 8 MeV. It is also found that gas target thickness plays an important role for efficient quasi-monoenergetic proton generation.

THPS020

Development of C⁶⁺ Laser Ion Source

ion, target, acceleration, ion-source

3460

A. Yamaguchi
Toshiba Corporation, Power And Industrial Systems Research and Development Center, Yokohama, Japan

A C⁶⁺ laser ion source has been developed for a heavy ion accelerator, which supplies pulsed ion beam for single-turn injection system of a synchrotron by one laser shot. A graphite plate is irradiated with a Q-switched Nd:YAG laser (10⁶⁴ nm of wavelength, 1.4 J of maximum laser energy, 10 ns of pulse duration) to generate carbon ions. The characteristics of the ion beam were studied by using the time-of-flight mass spectroscopy and the magnetic momentum analyzer. Results of the experiments are presented.

THPS062

Cavity-recirculated Laser Charge Stripping of Hydrogen Ions

neutron, cavity, radiation, ion

3568

I. Jovanovic
Penn State University, University Park, Pennsylvania, USA
R. Tikhoplav
RadiaBeam, Santa Monica, USA

Funding: This work is supported by the U.S. Department of Energy.
High-intensity proton accelerators such as those at the Oak Ridge National Laboratory’s Spallation Neutron Source require an intense, robust, reliable, and low-cost source of hydrogen ions. Laser-based charge stripping is a promising, high-efficiency method that could meet the requirements of present and future facilities. We are seeking to improve the efficiency of hydrogen ion stripping by an order of magnitude using laser recirculation. In our approach we recirculate a high-power laser using the technique termed recirculation injection by nonlinear gating, with a frequency-doubling nonlinear crystal as an efficient switch that allow pulse injection into the cavity. We present our progress on cavity development and the preliminary experimental assessment of cavity performance in high-radiation environment. Our experimental studies were conducted by irradiating the nonlinear crystal used in the laser cavity by fast neutrons in a research nuclear reactor and measuring its change in transmissivity.

THPS087

Engineering Prototype for a Compact Medical Dielectric Wall Accelerator

rfq, proton, kicker, acceleration

3636

A. Zografos, T. Brown, A. Hening, V. Joshkin, K. Leung, Y.K. Parker, H.T. Pearce-Percy, D. Pearson, M. Rougieri, J. Weir
CPAC, Livermore, CA, USA
R. Becker
SSS, Gelnhausen, Germany
D.T. Blackfield, G.J. Caporaso, Y.-J. Chen, S. Falabella, G. Guethlein, S.A. Hawkins, S.D. Nelson, B. R. Poole, J.A. Watson
LLNL, Livermore, California, USA
R.W. Hamm
R&M Technical Enterprises, Pleasanton, California, USA

Funding: Prepared by LLNL under Contract DE-AC52-07NA27344.
The Compact Particle Accelerator Corporation has developed an architecture to produce pulsed proton bunches that will be suitable for proton treatment of cancers. Subsystems include a RFQ injection system with a pulsed kicker to select the desired proton bunches and a linear accelerator incorporating a High Gradient Insulator with stacked Blumleins to produce the required voltage. The Blumleins are switched with solid state laser driven optical switches that are an integral part of the Blumlein assemblies. Other subsystems include a laser, a fiber optic distribution system, an electrical charging system and beam diagnostics. An engineering prototype has been constructed and it has been fully characterized. Results obtained from the engineering prototype support the development of an extremely compact 150 MeV system capable of modulating energy, beam current and spot size on a shot to shot basis within the next two years. The paper will detail the construction of the engineering prototype and discuss experimental results. In addition, future development milestones and commercialization plans will also be discussed.

THPS090

Development of the Pulse Radiolysis System with a Supercontinuum Radiation using Photonic Crystal Fiber

radiation, electron, gun, optics

3645

K.B. Ogata, R. Betto, Y. Hosaka, Y. Kawauchi, K. Sakaue, T. Suzuki, M. Washio
RISE, Tokyo, Japan
S. Kashiwagi
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
R. Kuroda
AIST, Tsukuba, Ibaraki, Japan

Funding: Work supported by JSPS Grant-in-Aid for Scientific Research (A) 10001690
In usage of radiation, it is important to study the process of chemical effects of ionizing radiation in a material. Pulse radiolysis is a method to trace these rapid initial chemical reactions by ionizing radiation. As a pump beam, we are using 5MeV electron beam produced from the S-band photo cathode RF-Gun. In nanosecond timescale pulse radiolysis, it is required the stable probe light of a broad spectrum. And especially in picosecond timescale pulse radiolysis, probe light should have short pulse width to use stroboscopic method. Therefore, in order to develop a wide range of timescale experimental system, we have been developing a Supercontinuum (SC) light as a probe light, which is generated by nonlinear optical process of short pulse IR laser in photonic crystal fiber (PCF). As a result, the SC light spectrum is broad enough to use as a probe light. Then we tried to measure the absorption spectrum of hydrated electron by SC light, we successfully observed good signal-noise ratio data both nanosecond and picosecond experiment with unified pulse　radiolysis system. In this conference, we will report details of these results and future prospects.

THPS098

Compact Gamma-ray Source for Non-destructive Detection of Nuclear Material in Cargo

microtron, photon, electron, neutron

3663

R. Hajima
JAEA/ERL, Ibaraki, Japan
I. Daito, T. Hayakawa, Y. Hayashi, M. Kando, H. Kotaki
JAEA, Kyoto, Japan
T. Hori, H. Ohgaki
Kyoto IAE, Kyoto, Japan
N. Kikuzawa
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
T. Shizuma
JAEA APRC, Ibaraki-ken, Japan

Funding: This work is supported by Strategic Funds for Promotion of Science and Technology (Grant No. 066).
A mono-energetic gamma-ray source based on laser Compton scattering is under development for non-destructive detection of nuclear material in cargo. In the detection system, we employ nuclear resonance fluorescence triggered by mono-energetic gamma-rays tuned at the resonance energy of nuclear material such as U-235. As a prototype, a 150-MeV microtron combined with a YAG laser to produce a 400-keV gamma ray is constructed at JAEA, where critical technologies are to be demonstrated for high-flux gamma-ray generation, 3x10⁵ ph/s. We also start to design a microtron at higher energy, 250 MeV, to produce a 2-MeV gamma-ray, which is required for the detection of U-235.

THPS099

Design Study of a Nuclear Material Detection System Based on a Quasi Monochromatic Gamma Ray Generator and a Nuclear Resonance Fluorescence Gamma Ray Detection System

neutron, scattering, background, photon

3666

T. Kii, T. Hori, K. Masuda, H. Ohgaki, M. Omer
Kyoto IAE, Kyoto, Japan
R. Hajima, T. Hayakawa, M. Kando, T. Shizuma
JAEA, Ibaraki-ken, Japan
T. Misawa, C.H. Pyeon
KURRI, Osaka, Japan
H. Toyokawa
AIST, Ibaraki, Japan

Funding: This work was partially supported by Special Coordination Funds for romoting Science and Technology in Japan,
Nuclear Resonance Fluorescence (NRF) measurement is a powerful tool for isotope detection for the homeland security such as a nondestructive measurement of containers at airports or harbors and detection or identification of special nuclear materials. In this paper, we will discuss on basic design of a quasi-monochromatic gamma-ray generator based on the backward Compton scattering of laser light on high-energy electrons and an NRF gamma ray detection system using a high-speed scintillation detector.

THPS102

Novel Schemes for the Narrow Band Sparc THz Source using a Comb like e-beam

linac, radiation, cavity, electron

3672

B. Marchetti
INFN-Roma II, Roma, Italy
M. Boscolo, M. Castellano, E. Chiadroni, M. Ferrario, B. Spataro, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
C. Ronsivalle
ENEA C.R. Frascati, Frascati (Roma), Italy

The development of radiation sources in the THz spectral region has become more and more interesting because of the peculiar characteristics of this radiation: it is non ionizing, it penetrates dielectrics, it is highly absorbed by polar liquids, highly reflected by metals and reveals specific "fingerprint" absorption spectra arising from fundamentals physical processes. The THz source at SPARC is an accelerator based source for research investigations (e.g. material science, biology fields). By means of e-beam manipulation technique, a longitudinal modulated beam, the so-called comb beam, can be produced at Sparc. In terms of THz sources, such e-beam distribution allows to produce high intensitiy narrow band THz radiation, whose spectrum strongly depends on the charge distribution inside the e-beam. Different linac schemes are compared. In particular, spectra obtained using the comb-beam compression through velocity bunching including a IV harmonic RF section is showed.