IPAC2012 - List of Keywords (photon)

Paper	Title	Other Keywords	Page
MOEPPB010	Measurement of Satellite Bunches at the LHC	emittance, synchrotron, ion, coupling	97
	A. Jeff, M. Andersen, A. Boccardi, S. Bozyigit, E. Bravin, T. Lefèvre, A. Rabiller, F. Roncarolo CERN, Geneva, Switzerland A.S. Fisher SLAC, Menlo Park, California, USA C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: Adam Jeff is a DITANET fellow, supported by the EU's Marie Curie actions contract PITN-GA-2008-215080. The RF gymnastics involved in the delivery of proton and lead ion bunches to the LHC can result in satellite bunches of varying intensity occupying the nominally empty RF buckets. Quantification of these satellites is crucial for bunch-by-bunch luminosity normalization as well as for machine protection. We present an overview of the longitudinal density monitor (LDM) which is the principal instrument for the measurement of satellite bunches in the LHC. The LDM uses single photon counting of synchrotron light. The very high energies reached in the LHC, combined with a dedicated undulator for diagnostics, allow synchrotron light measurements to be made with both protons and heavy ions. The arrival times of photons are collected over a few million turns, with the resulting histogram corrected for the effects of the detector’s deadtime and afterpulsing in order to reconstruct the longitudinal profile of the entire LHC ring. The LDM has achieved a dynamic range in excess of 10⁵ and a time resolution of 90 ps. Example results are presented and the measurements are benchmarked against satellite distributions based on collision data from the LHC experiments.

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

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

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

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

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

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

MOPPP062	Soleil Emittance Reduction using a Robinson Wiggler	emittance, brightness, damping, wiggler	702
	H.B. Abualrob, P. Brunelle, M.-E. Couprie, O. Marcouillé, A. Nadji, L.S. Nadolski, R. Nagaoka SOLEIL, Gif-sur-Yvette, France
	For both synchrotron light sources as SOLEIL and colliders, the emittance is one of the key parameters to increase the photon brightness and the beam luminosity. In order to decrease the emittance, the ring optics is built on very focusing lattices leading to large chromaticities and potential reduction of the dynamics aperture and momentum transverse acceptance. Thus, some facilities have installed damping wigglers in zero dispersion straight sections to relax the optics and to reach sub-nanometer horizontal emittances. This solution requires however tens or hundreds meters of insertion devices. For storage ring equipped with zero-gradient bending magnets, an alternative solution can be given by installing a single Robinson wiggler [1] in a dispersive section enabling to divide the emittance by a factor 2. The uniqueness of this wiggler results from the presence of an alternated gradient superimposed the main periodic magnetic field. This paper recalls the concept of the wiggler, presents the expected gain for SOLEIL storage ring with the impact on the linear optics and the brightness. A preliminary magnetic design is also proposed. [1] K.W. Robinson, Phys. Rev, p. 373 (1958).

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

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

MOPPP078	Status of the First Planar Superconducting Undulator for the Advanced Photon Source	undulator, controls, status, radiation	744
	Y. Ivanyushenkov, M. Abliz, K.D. Boerste, T.W. Buffington, C.L. Doose, J.D. Fuerst, Q.B. Hasse, M. Kasa, S.H. Kim, R. Kustom, E.R. Moog, D. Skiadopoulos, E. Trakhtenberg, I. Vasserman ANL, Argonne, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Superconducting technology offers the possibility of building short-period undulators for synchrotron light sources. Such undulators will deliver higher fluxes at higher photon energies to the light source user community. The Advanced Photon Source (APS) team is building the first superconducting planar undulator to be installed in the APS storage ring. The current status of the project is presented in this paper.

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

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

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

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

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

MOPPR050	Design and Analysis of EPU XBPM in TPS	undulator, synchrotron, synchrotron-radiation, radiation	894
	A. Sheng, C.M. Cheng, C.K. Kuan NSRRC, Hsinchu, Taiwan D. Shu ANL, Argonne, USA
	Several planer and elliptical polarized undulators (EPU) beam lines have been proposed and are to be built for Taiwan Photon Source (TPS) in National Synchrotron Research Center (NSRRC). Due to its complexity, with changing of vertical as well as horizontal deflection parameters (Kx and Ky), one finds that regular diamond bladed photon beam position monitor (XBPM) would not be sufficient to detect the center location of the undulator. A new conceptual design of EPU XBPM has been analyzed both in thermal as well as photon aspects. A prototype by taking advantage of fluorescent some of the diamond detectors has been designed and implemented in Taiwan Light Source (TLS) for testing. Some analysis and design scenarios are presented in this paper.

MOPPR053	Improvement of BPM System for the Siam Photon Source	storage-ring, shielding, synchrotron, controls	903
	P. Songsiriritthigul, S. Boonsuya, S. Klinkhieo, P. Klysubun, S. Krainara, P. Sudmuang, N. Suradet SLRI, Nakhon Ratchasima, Thailand J.-R. Chen, H.P. Hsueh, Y.-H. Liu NSRRC, Hsinchu, Taiwan S. Rujirawat, P. Songsiriritthigul Suranaree University of Technology, Nakhon Ratchasima, Thailand
	The Siam Photon Source (SPS) is the first synchrotron light source ever built by modifying and relocating a light source from one country to another. The SPS produced its first light in Dec 2001. The machine has been used to provide regularly synchrotron light for users since 2005. Systematic studies and investigations of the machine have properly been carried out under the supervision of the International Advisory Committee of SLRI in the last two years. This report describes the improvement of the beam position monitoring (BPM) system for the 1.2 GeV storage ring of SPS. The efficiency and reliability of the original BPM system was greatly hindered by the low quality signal cables. The replacement with the higher quality (lower loss and better interference shielding) BPM cables and the implementation of a separated cable tray for the BPM cables have significantly improved the quality of the BPM signals, allowing the possibilities for machine study and thus providing further improvement of the machine. Detailed descriptions of the work on the BPM electronic boards will be described. The measurement results before and after the improvement of the BPM system will also be presented.

MOPPR054	Beam Size Measurement at Siam Photon Source Storage Ring	synchrotron, storage-ring, monitoring, radiation	906
	P. Sudmuang, N. Deethae, P. Klysubun, S. Krainara, T. Poolampong, K. Sitisart, N. Suradet SLRI, Nakhon Ratchasima, Thailand
	Synchrotron radiation interferometer and direct imaging setups have been installed and subsequently utilized to investigate transverse beam profile at the Siam Photon Source (SPS). Details of the optical setup as well as the beam sizes determined from the measurement will be presented. Comparison between the measured and theoretical values as established by linear optics calibration will be made and discussed. In order to demonstrate the beam profiling capability of the interferometer and direct imaging systems, measurements with different operating parameters have been carried out and the results will be presented as well.

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

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

TUOBB01	A European Proposal for the Compton Gamma-ray Source of ELI-NP	laser, electron, emittance, scattering	1086
	L. Serafini, I. Boscolo, F. Broggi, V. Petrillo Istituto Nazionale di Fisica Nucleare, Milano, Italy O. Adriani, G. Graziani, G. Passaleva INFN-FI, Sesto Fiorentino, Italy S. Albergo, A. Tricomi INFN-CT, Catania, Italy D. Alesini, M.P. Anania, A. Bacci, R. Bedogni, M. Bellaveglia, C. Biscari, R. Boni, M. Boscolo, M. Castellano, E. Chiadroni, A. Clozza, E. Di Pasquale, G. Di Pirro, A. Drago, A. Esposito, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, F. Marcellini, C. Maroli, G. Mazzitelli, E. Pace, L. Pellegrino, R. Ricci, M. Serio, F. Sgamma, B. Spataro, A. Stecchi, A. Stella, P. Tomassini, C. Vaccarezza, S. Vescovi, F. Villa INFN/LNF, Frascati (Roma), Italy D. Angal-Kalinin, J.A. Clarke, B.D. Fell, A.R. Goulden, J.D. Herbert, S.P. Jamison, P.A. McIntosh, R.J. Smith, S.L. Smith STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom P. Antici, M. Coppola, L. Lancia, A. Mostacci, L. Palumbo URLS, Rome, Italy N. Bliss, B.G. Martlew STFC/DL, Daresbury, Warrington, Cheshire, United Kingdom P. Cardarelli, M. Gambaccini INFN-Ferrara, Ferrara, Italy L. Catani, A. Cianchi INFN-Roma II, Roma, Italy I. Chaikovska, O. Dadoun, A. Stocchi, A. Variola, Z.F. Zomer LAL, Orsay, France C. De Martinis INFN/LASA, Segrate (MI), Italy F. Druon, P. Fichot ILE, Palaiseau Cedex, France E. Iarocci University of Rome "La Sapienza", Rome, Italy M. Migliorati Rome University La Sapienza, Roma, Italy A.-S. Müller IN2P3, Paris, France V. Nardone Università di Roma I La Sapienza, Roma, Italy C. Ronsivalle ENEA C.R. Frascati, Frascati (Roma), Italy M. Veltri Uniurb, Urbino (PU), Italy
	A European proposal is under preparation for the Compton gamma-ray Source of ELI-NP. In the Romanian pillar of ELI (the European Extreme Light Infrastructure) an advanced gamma-ray beam is foreseen, coupled to two 10 PW laser systems. The photons will be generated by Compton back-scattering in the collision between a high quality electron beam and a high power laser. A European collaboration formed by INFN, Univ. of Roma La Sapienza, Orsay-LAL of IN2P3, Univ. de Paris Sud XI and ASTeC at Daresbury, is preparing a TDR exploring the feasibility of a machine expected to achieve the Gamma-ray beam specifications: energy tunable between 1 and 20 MeV, narrow bandwidth (0.3%) and high spectral density, 10⁴ photons/sec/eV. We will describe the lay-out of the 720 MeV RF Linac and the collision laser with the associated optical cavity, as well as the optimized beam dynamics to achieve maximum phase space density at the collision, taking into account beam loading and beam break-up due to the acceleration of long bunch trains. The predicted gamma-ray spectra will be evaluated as the gamma photons collimators background. An option for electron bunches recirculation will also be illustrated.
	Slides TUOBB01 [5.099 MB]

TUOBB03	Status of the FERMI@Elettra Project	FEL, laser, electron, radiation	1092
	M. Svandrlik, E. Allaria, L. Badano, S. Bassanese, F. Bencivenga, E. Busetto, C. Callegari, F. Capotondi, D. Castronovo, M. Coreno, P. Craievich, I. Cudin, G. D'Auria, M. Dal Forno, M.B. Danailov, R. De Monte, G. De Ninno, A.A. Demidovich, M. Di Fraia, S. Di Mitri, B. Diviacco, A. Fabris, R. Fabris, W.M. Fawley, M. Ferianis, E. Ferrari, L. Fröhlich, P. Furlan Radivo, G. Gaio, L. Giannessi, R. Gobessi, C. Grazioli, E. Karantzoulis, M. Kiskinova, M. Lonza, B. Mahieu, C. Masciovecchio, S. Noè, F. Parmigiani, G. Penco, E. Principi, F. Rossi, L. Rumiz, C. Scafuri, S. Spampinati, C. Spezzani, C. Svetina, M. Trovò, A. Vascotto, M. Veronese, R. Visintini, M. Zaccaria, D. Zangrando, M. Zangrando ELETTRA, Basovizza, Italy
	Funding: The work was supported in part by the Italian Ministry of University and Research under grants FIRB-RBAP045JF2 and FIRB-RBAP06AWK3. The FERMI@Elettra seeded Free Electron Laser has provided the first photons to the experimental stations during 2011. The first FEL line in operation is FEL-1, covering the wavelength range between 100 nm and 20 nm. The facility will be opened to users by the end of 2012. In the meantime the installation of the second FEL line, FEL-2 covering the higher energy range down to 4 nm, is progressing on schedule and first tests have started. A description of the status of the project is presented here.
	Slides TUOBB03 [5.316 MB]

TUEPPB009	First Measurements of the FACET Coherent Terahertz Radiation Source	radiation, electron, diagnostics, insertion	1134
	Z. Wu, E. Adli, A.S. Fisher, M.J. Hogan, H. Loos SLAC, Menlo Park, California, USA
	Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515. The Facility for Accelerator science and Experimental Tests (FACET) at SLAC provides a high peak current, sub-ps bunched beam that is ideal for THz photon generation via coherent transition radiation. This paper presents preliminary characterization of the THz pulses generated by FACET electron beam. A one-micron thick Ti foil has been inserted into the beam path and the radiated photons collected. Michelson spectroscopy yields frequency content spanning from 0.25 THz to 2.3 THz and peaked at around 0.5 THz. Multiple scans at different bunch compression show a monotonic increase of the peak radiation frequency as the electron bunch gets shorter. Using the Kramers-Kronig relation, the temporal profile of the THz pulse is reconstructed from the power spectrum indicating a ~4 picosecond main pulse followed by a long oscillating tail due to the water absorption lines and detector response. Knife-edge scans measure a 4.4 mm x 4.8 mm transverse spot size at the focal point of the THz optical path. The total collected energy per pulse is 0.69 mJ measured by a Joulemeter. Fitting this total energy to the spatiotemporal profile of the THz pulse yields peak e-field amplitude of 1.5 MV/cm.

TUPPC013	Optimization of Lower Emittance Optics for the SPring-8 Storage Ring	optics, emittance, lattice, brilliance	1182
	Y. Shimosaki, K.K. Kaneki, M. Masaki, T. Nakamura, H. Ohkuma, J. Schimizu, K. Soutome, S. Takano, M. Takao JASRI/SPring-8, Hyogo-ken, Japan
	A design work of the present SPring-8 storage ring is in progress to improve its performance. The linear optics has been changed to reduce the natural emittance below the nominal of 3.4 nmrad at 8 GeV, and the nonlinear optics has been optimized with a genetic algorithm to suppress the amplitude-dependent tune shifts and to enlarge the dynamic aperture. As a preliminary study, the optics with the natural emittance of 2.4 nmrad at 8 GeV has been examined, theoretically and experimentally. In this optics, 1.5 times higher brilliance for 10 keV photons than the present can theoretically be expected for the standard undulator beamline. The improved optics design and its beam performance will be presented in detail. In this presentation, a optics for a future upgrade of the SPring-8 (SPring-8 II) will not be discussed, which is a full-scale major lattice modification, while the method we used in optimizing the nonlinear optics can also be adopted to the SPring-8 II. Y. Shimosaki et al., "Design Study of Nonlinear Optics for a Very Low-emittance Lattice of the SPring-8 II," these proceedings.

TUPPC075	Study of Nonlinear Beam Dynamics Effects for DEPU at SSRF	polarization, undulator, electron, focusing	1347
	M. Zhang, Q.G. Zhou SINAP, Shanghai, People's Republic of China
	A pair of EPUs (DEPU) with the period 58mm and 148mm, covering the energy ranges from 20 to 200eV and 200 to 2000eV of arbitrary polarized light, will be developed for the SSRF soft X-ray beam line for ARPES and PEEM. The effects of DEPU to tune-shift produced by the nonlinear beam dynamics are studied and the results are presented in this paper. The corresponding magnet field shimming technology to reduce these effects is also investigated.

TUPPD033	Conceptual Design of a Positron-annihilation System for Generation of Quasi-monochromatic Gamma Rays	positron, target, dipole, electron	1476
	R.J. Abrams, C.M. Ankenbrandt, K.B. Beard, G. Flanagan, R.P. Johnson, C. Y. Yoshikawa Muons, Inc, Batavia, USA A. Afanasev GWU, Washington, USA
	A conceptual design is presented for a system consisting of the following: an electron accelerator and production target to produce positrons, a dipole magnet and wedge to compress the positron momenta to be nearly monochromatic, a magnetic transport system to focus and direct the positrons to a converter, and a converter in which the positrons annihilate in flight to produce quasi-monochromatic gamma rays. The system represented is designed to produce ~10 MeV gammas, but it can also be designed for other energies.

TUPPD036	Novel Designs for Undulator Based Positron Sources	positron, target, undulator, damping	1485
	M. Jenkins Cockcroft Institute, Warrington, Cheshire, United Kingdom I.R. Bailey, M. Jenkins Lancaster University, Lancaster, United Kingdom
	At least three proposed future colliders(ILC, CLiC and LHeC) require a positron source with a yield greater than 10¹⁴ e+/s. An undulator based positron source has the potential to provide the required yield. This design generates gamma rays by using a high energy electron beam traveling through a superconducting helical undulator. The gamma rays then pair produce in a titanium alloy target to produce positrons. This is the ILC baseline positron source. Two drawbacks to the undulator-based positron source are that it couples the positron source to the electron beam operation and that it exhibits a low conversion efficiency of photons to positrons. A self-seeding undulator-based positron source has been proposed. This starts with a low intensity positron beam which travels through the undulator to produce more positrons which are recirculated through the source to increase the intensity until the design yield is achieved. Multiple targets have been added to increase the conversion efficiency of the positron source. In this study I present simulation results for such a design and consider the feasibility of this design at the ILC, CLiC or LHeC.

TUPPD050	Investigation of Laser-cleaning Process on Lead Photocathodes	laser, electron, cathode, high-voltage	1515
	S.G. Schubert, R. Barday, T. Kamps, T. Quast, A. Varykhalov HZB, Berlin, Germany R. Nietubyć The Andrzej Soltan Institute for Nuclear Studies, Centre Świerk, Świerk/Otwock, Poland F. Siewert BESSY GmbH, Berlin, Germany J. Smedley BNL, Upton, Long Island, New York, USA G. Weinberg FHI, Berlin, Germany
	Funding: Work supported by Bundesministerium für Bildung und Forschung and Land Berlin. Metal photocathodes are widely used in electron injectors due to their stability and long life time; unfortunately they exhibit low quantum efficiency. Due to adsorption of contaminants the work function increases and thus the quantum efficiency is further reduced. In order to increase the quantum efficiency of our Pb cathode we performed a cleaning procedure by means of a high power excimer laser as suggested by Smedley. The process was studied on witness samples in a combined photo emission, SEM and quantum efficiency measurement study. Thin Lead films were arc-deposited on optical polished Mo-substrates. Before and after irradiation the sample was analyzed at 140 eV photon energy at a XPS/ARPES end station at the synchrotron radiation source Bessy II. We followed the change of the Pb 5d signals. In the initial situation we observed signals originating from metallic Pb and Pb in the oxidized state, respectively. Since the surface roughness is of concern for the injector performance it was examined before and after the irradiation procedure with white-light-interferometry and the surface morphology by means of SEM. J. Smedley et al, PRST-AB 11, 013502 (2008). ** Rao, T. et al., IPAC 2010, THPEC020 (2010).

TUPPD069	Schottky-Enabled Photoemission and Dark Current Measurements - Toward an Alternate Approach to Fowler-Nordheim Plot Analysis	gun, laser, site, cathode	1563
	E.E. Wisniewski, W. Gai, J.G. Power ANL, Argonne, USA H. Chen, Y.-C. Du, Hua, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, Y. You TUB, Beijing, People's Republic of China A. Grudiev, W. Wuensch CERN, Geneva, Switzerland E.E. Wisniewski Illinois Institute of Technology, Chicago, Illinois, USA
	Field-emitted dark current, a major gradient-limiting factor in RF cavities, is usually analyzed via Fowler-Nordheim (FN) plots. Traditionally, field emission is attributed to geometrical perturbations on the bulk surface whose field enhancement factor (beta) and the emitting area (A) can be extracted from the FN plot. Field enhancement factors extracted in this way are typically much too high (1 to 2 orders of magnitude) to be explainable by either the geometric projection model applied to the measured surface roughness or by field enhancement factors extracted from Schottky-enabled photoemission measurements. We compare traditional analysis of FN plots to an alternate approach employing local work function variation. This is illustrated by comparative analysis of recent dark current and Schottky-enabled photoemission data taken at Tsinghua S-band RF gun. We conclude by describing a possible experimental plan for discrimination of variation of local work function vs. local field enhancement.

TUPPD070	Kelvin Probe Studies of a Cesium Telluride Photocathode for the AWA Photoinjector	cathode, electron, vacuum, wakefield	1566
	E.E. Wisniewski, K.C. Harkay, Z.M. Yusof ANL, Argonne, USA L.K. Spentzouris, J. Terry, D.G. Velazquez, E.E. Wisniewski Illinois Institute of Technology, Chicago, Illinois, USA
	Cesium telluride is an important photocathode as an electron source for particle accelerators. It has a relatively high quantum efficiency (>1%), is sufficiently robust in a photoinjector, and has a long lifetime. This photocathode is grown in-house for the new Argonne Wakefield Accelerator (AWA) to produce high charge per bunch (~50 nC). Here, we present a study of the "work function" of a cesium telluride photocathode using the Kelvin Probe technique. The study includes an investigation of the correlation between the quantum efficiency and the work function, the effect of photocathode aging, the surprising effect of UV exposure on the work function, and the puzzling behavior of the work function during and after photocathode rejuvenation via heating.

TUPPD083	Raising Photoemission Efficiency with Surface Acoustic Waves	electron, polarization, linac, vacuum	1596
	A. Afanasev, F. Hassani, C.E. Korman GWU, Washington, USA V.G. Dudnikov, R.P. Johnson Muons, Inc, Batavia, USA M. Poelker, K.E.L. Surles-Law JLAB, Newport News, Virginia, USA
	Funding: Supported in part by DOE STTR Grant DE-SC0006256. Notice: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177 We are developing a novel technique that may help increase the efficiency and reduce costs of photoelectron sources used at electron accelerators. The technique is based on the use of Surface Acoustic Waves (SAW) in piezoelectric materials, such as GaAs, that are commonly used as photocathodes. Piezoelectric fields produced by the traveling SAW spatially separate electrons and holes, reducing their probability of recombination, thereby enhancing the photoemission quantum efficiency of the photocathode. Additional advantages could be increased polarization provided by the enhanced mobility of charge carriers that can be controlled by the SAW and the ionization of optically-generated excitons resulting in the creation of additional electron-hole pairs. It is expected that these novel features will reduce the cost of accelerator operation. A theoretical model for photoemission in the presence of SAW has been developed, and experimental tests of the technique are underway.

TUPPP004	Low-alpha Operation for the SOLEIL Storage Ring	optics, injection, coupling, radiation	1608
	M.-A. Tordeux, J. Barros, A. Bence, P. Brunelle, N. Hubert, M. Labat, P. Lebasque, A. Nadji, L.S. Nadolski, J.-P. Pollina SOLEIL, Gif-sur-Yvette, France C. Evain PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France
	The low momentum compaction factor (alpha) operation has been recently established on the SOLEIL Storage Ring. Both time resolved X-ray and THz radiation user communities are taking benefit from a hybrid filling pattern with a 4.7 ps RMS bunch length. At a value of 1.7 10^-5 (nominal alpha /25) and a current per bunch of 65 μA, stable THz radiation is produced in the range of 8 - 20 cm^-1 (measurements and comparison with Coherent Synchrotron Radiation (CSR) modeling are reported elsewhere, ). Several low-alpha optics have been investigated and the optics presented at IPAC’11 has been selected for the operation. This paper presents the comprehensive experimental characterization of this optics. Specificities of the low-alpha operation, driven by the very demanding user experiments, are reviewed: closed orbit stability issues, extremely tight injected current step when refilling which implies a specific Linac tuning, low current diagnostics optimization, short bunch measurements, insertion devices effect on the CSR characteristics and radiation safety aspects justified by beam losses at injection. C. Evain, A. Loulergue et al., this conference. ** E. Roussel et al., this conference.

TUPPP017	Lattice Design of the SSRF Storage Ring with Superbend	lattice, emittance, dipole, optics	1644
	S.Q. Tian, B.C. Jiang, H.H. Li, M.Z. Zhang, W.Z. Zhang, Z.T. Zhao SINAP, Shanghai, People's Republic of China
	The SSRF storage ring is being investigated by upgrading with normal conducting superbend of 3 T. The bending magnets are shortened, and thus some additional straight sections with the length of about 2 m are created in the center of the arc cell. They can be used to install more insertion devices. The lattice adjustment and the optics design are presented in this paper, where much efforts are made to maintain the effective emittance along the ring with respect to the nominal optics.

TUPPP027	Subpicosecond Laser Slicing X-Ray Source for Time-resolved Research at TPS	wiggler, laser, emittance, lattice	1671
	W.K. Lau, M.C. Chou, C.-S. Hwang, A.P. Lee, Y.-C. Liu, G.-H. Luo NSRRC, Hsinchu, Taiwan N.Y. Huang NTHU, Hsinchu, Taiwan
	The 3 GeV Taiwan Photon Source (TPS) under construction at NSRRC should be ready for user run in 2014. X-ray users in many research areas will then be benefited. However, there has been a growing interest in ultrafast time-resolved research in the island. The feasibility of using ultrafast laser for electron-beam slicing at TPS to produce sub-picosecond x-ray pulses is being investigated recently. The design and layout of a laser slicing scheme with W250 wiggler as the energy modulator in a 7 m medium straight section and EPU48 and IU22 radiators in other straight sections will be presented. It will offer the unique opportunity to gain experience in experimental techniques needed for FEL science.

TUPPP032	Use of Multi-objective Methods for Choosing Undulators for Storage Rings	brightness, undulator, target, storage-ring	1680
	M. Borland ANL, Argonne, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Users of storage ring light sources generally rely on undulators to provide the highest brightness. Choice of the optimal undulator period is complicated by the fact that users do not operate at a single photon energy or place equal weight on operation at all photon energies of interest. In addition, some users may be best served by a double- or triple-period revolver device. In this paper, we present a method of narrowing the choice of undulator periods based on multi-objective techniques. Applications are shown in the context of the Advanced Photon Source Upgrade.

TUPPP052	Status of FLASH	FEL, electron, laser, undulator	1715
	K. Honkavaara, B. Faatz, J. Feldhaus, S. Schreiber, R. Treusch, M. Vogt DESY, Hamburg, Germany
	FLASH at DESY (Hamburg, Germany) is a free-electron laser user facility driven by a superconducting 1.25 GeV linac based on TESLA technology. During the 3rd user period from September 2010 to September 2011, totally 3740 hours of FEL radiation has been delivered to FEL experiments at more than 30 different wavelengths between 4.7 nm and 45 nm. In addition, beam time has been dedicated to general accelerator physics studies and developments related to the future projects like the European XFEL and the International Linear Collider. After a 3.5 months shutdown in autumn 2011 due to civil construction for a second undulator beamline - FLASH2 - and a following commissioning and study period, 2012 is mainly dedicated to FEL user experiments. This paper summarizes the operation status of the FLASH facility and gives also a short review of the accelerator studies carried out in 2011 and early 2012. The mid-term plans including FLASH2 are presented as well.

TUPPP073	Machine Parameter Studies for an FEL Facility Using STAFF	FEL, undulator, linac, emittance	1768
	M.W. Reinsch, B. Austin, J.N. Corlett, L.R. Doolittle, P. Emma, G. Penn, D. Prosnitz, J. Qiang, A. Sessler, M. Venturini LBNL, Berkeley, California, USA J.S. Wurtele UCB, Berkeley, California, USA
	Designing an FEL facility requires balancing multiple science needs, FEL and accelerator physics constraints, and engineering limitations. STAFF (System Trade Analysis for an FEL Facility) is a MATLAB program that enables the user to rapidly explore a large range of Linac and FEL design options to meet science requirements. The code uses analytical models such as the Ming Xie formulas when appropriate and look-up tables when necessary to maintain speed and flexibility. STAFF's modular design simplifies the inclusion of new physics models for FEL harmonics, wake fields, cavity higher-order modes and aspects of linac design such as the optimization of a laser heater, harmonic linearizer, and one or more bunch compressors. Code for the microbunching instability has been included as well. STAFF also supports multiple undulator technologies. STAFF permits the user to study error tolerances and multiple beamlines so as to explore the full capabilities of an entire user facility. This makes it possible to optimize the integrated system in terms of performance metrics such as photons/pulse, photons/sec and tunability range.

TUPPP079	Design Alternatives for a Free Electron Laser Facility	FEL, linac, undulator, electron	1777
	K. Jacobs, J. Bisognano, R.A. Bosch, D. Eisert, M.V. Fisher, M.A. Green, R.G. Keil, K.J. Kleman, J.G. Kulpin, G.C. Rogers, R. Wehlitz UW-Madison/SRC, Madison, Wisconsin, USA T. Chiang, T.J. Miller University of Illinois, Urbana, USA J.E. Lawler, D. Yavuz UW-Madison/PD, Madison, Wisconsin, USA R.A. Legg JLAB, Newport News, Virginia, USA R.C. York FRIB, East Lansing, Michigan, USA
	The University of Wisconsin-Madison is continuing design efforts for a vacuum ultraviolet/X-ray Free Electron Laser facility. The design incorporates seeding the FEL to provide fully coherent photon output at energies up to ~1 keV. The focus of the present work is to minimize the cost of the facility while preserving its performance. To achieve this we are exploring variations in the electron beam driver for the FEL, in undulator design, and in the seeding mechanism. Design optimizations and trade-offs between the various technologies and how they affect the FEL scientific program will be presented.

TUPPR002	Simulations of Positron Polarization in the Undulator-Based Source	undulator, positron, polarization, electron	1810
	A. Ushakov, O.S. Adeyemi, V.S. Kovalenko, L.I. Malysheva, G.A. Moortgat-Pick University of Hamburg, Hamburg, Germany A.F. Hartin DESY, Hamburg, Germany S. Riemann, F. Staufenbiel DESY Zeuthen, Zeuthen, Germany
	Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE The generation of an intense and highly polarized positron beam is a challenge. The design for the International Linear Collider proposes a positron source based on a helical undulator located at the end of the electron linac. This design allows us to utilize a high energy linear accelerator with both electron and positron beams polarized. The polarization of the positron beam can be enhanced using a photon collimator. The optimization of positron yield and polarization for a wide energy range has been studied for different undulator parameters and collimator designs, taking into account realistic parameters for the capture section. In particular, the effects of misalignment and tolerances are considered.

TUPPR040	Update on ILC Positron Source Study at ANL	positron, undulator, polarization, electron	1906
	W. Liu, W. Gai ANL, Argonne, USA
	As the new ILC baseline has moved the positron production to the end of electron main linac, both the drive beam energy and beamline layouts have also been changed for the positron source. Now the drive beam energy will be varying from 150GeV to 250GeV and 500GeV (for TeV upgrade) as the colliding center of mass (CM) energy changes. Systematic studies on the performance of positron source under different running scenarios have been done at ANL and the results are presented in this paper.

TUPPR042	On the Polarization Upgrade of ILC Undulator-based Positron Source	polarization, positron, undulator, electron	1912
	W. Liu, W. Gai ANL, Argonne, USA S. Riemann DESY, Hamburg, Germany A. Ushakov University of Hamburg, Hamburg, Germany
	The current nominal polarization for ILC undulator based positron source is 30% without photon collimators. In order to improve the effective luminosity, an upgrade of positron source with higher polarization is required. Some studies on the upgrade options have been done at both DESY and ANL, and the results are presented in this paper.

TUPPR062	The Conceptual Design of a Vacuum System for the ILC Damping Rings Incorporating Electron Cloud Mitigation Techniques	vacuum, wiggler, electron, damping	1960
	J.V. Conway, Y. Li, M.A. Palmer CLASSE, Ithaca, New York, USA
	Funding: Work Supported by DOE Award DE-SC0006505. We describe the conceptual design of the vacuum system for the damping rings of the International Linear Collider. The design incorporates a range of techniques to suppress the development of the electron cloud (EC) in the positron ring. These techniques include coatings with low secondary electron yield (SEY), grooved chambers, clearing electrodes and antechambers for photoelectron control. The EC mitigation choices are based on the ILC Electron Cloud R&D program, which has been conducted at the Cornell Electron-Positron Storage Ring Test Accelerator (CesrTA) and at other collaborating institutions. The conceptual designs for vacuum chambers in drifts, dipoles, wigglers and quadrupoles are presented. The International Linear Collider: A Technical Progress Report, E. Elsen et al., Eds., pp. 71-81 (2011).

TUPPR063	Investigation into Electron Cloud Effects in the ILC Damping Ring Design	vacuum, wiggler, electron, lattice	1963
	J.A. Crittenden, J.V. Conway, G. Dugan, M.A. Palmer, D. L. Rubin CLASSE, Ithaca, New York, USA L.E. Boon, K.C. Harkay ANL, Argonne, USA M.A. Furman LBNL, Berkeley, California, USA S. Guiducci INFN/LNF, Frascati (Roma), Italy M.T.F. Pivi, L. Wang SLAC, Menlo Park, California, USA
	Funding: Work supported by the U.S. Department of Energy DE-SC0006506 We report modeling results for electron cloud buildup in the ILC damping ring lattice design. Updated optics, wiggler magnet, and vacuum chamber designs have recently been developed for the 5-GeV, 3.2-km racetrack layout. An analysis of the synchrotron radiation profile around the ring has been performed, including the effect of photon scattering on the interior of the vacuum chamber. Operational implications of the resulting electron cloud buildup will be discussed.

TUPPR064	Time-resolved Shielded-Pickup Measurements and Modeling of Beam Conditioning Effects on Electron Cloud Buildup at CesrTA	vacuum, electron, simulation, pick-up	1966
	J.A. Crittenden, Y. Li, X. Liu, M.A. Palmer, S. Santos, J.P. Sikora CLASSE, Ithaca, New York, USA S. Calatroni, G. Rumolo CERN, Geneva, Switzerland S. Kato KEK, Ibaraki, Japan
	Funding: Work supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the U.S. Department of Energy DE-FC02-08ER41538. The Cornell Electron Storage Ring Test Accelerator program includes investigations into electron cloud buildup in vacuum chambers with various coatings. Two 1.1-m-long sections located symmetrically in the east and west arc regions are equipped with BPM-like pickup detectors shielded against the direct beam-induced signal. They detect cloud electrons migrating through an 18-mm-diameter pattern of holes in the top of the chamber. A digitizing oscilloscope is used to record the signals, providing time-resolved information on cloud development. We present new measurements of the effect of beam conditioning on a newly-installed amorphous carbon coated chamber, as well as on a diamond-like carbon coating. The ECLOUD modeling code is used to quantify the sensitivity of these measurements to model parameters, differentiating between photoelectron and secondary-electron production processes.

WEOBB02	Refraction Contrast Imaging via Laser-Compton X-Ray Using Optical Storage Cavity	laser, electron, cavity, linac	2146
	K. Sakaue, T. Aoki, M. Washio RISE, Tokyo, Japan M.K. Fukuda, Y. Honda, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan
	We have been developing a pulsed-laser storage technique in a super-cavity for a compact x-ray sources. The pulsed-laser super-cavity enables to make high peak power and small waist laser at the collision point with the electron beam. Recently, using 357 MHz mode-locked Nd:VAN laser pulses which stacked in a super-cavity scattered off a multi-bunch electron beam, we obtained a multi-pulse x-rays through the laser-Compton scattering. Then, we performed a X-ray imaging via laser-Compton X-ray. The images have edge enhancement by refraction contrast because the X-ray source spot size was small enough. This is one of the evidences that laser-Compton X-ray is high quality. Our laser-Compton experimental setup, the results of X-ray imaging and future prospective will be presented at the conference.
	Slides WEOBB02 [4.393 MB]

WEPPC033	RF and Surface Properties of Bulk Niobium and Niobium Film Samples	niobium, electron, quadrupole, collider	2278
	T. Junginger, W. Weingarten CERN, Geneva, Switzerland R. Seviour University of Huddersfield, Huddersfield, United Kingdom C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: Work supported by the German Doctoral Students program of the Federal Ministry of Education and Research (BMBF) The surface resistance Rs of superconducting cavities can be obtained from the unloaded quality factor Q0. Since RS varies strongly over the cavity surface its value must be interpreted as averaged over the whole cavity surface. A more convenient way to investigate the surface resistance of superconducting materials is therefore to examine small samples, because they can be manufactured cheaply, duplicated easily and used for further surface analyses. At CERN a compact Quadrupole Resonator has been developed for the RF characterization of superconducting samples at different frequencies. In this contribution, results from measurements on bulk niobium and niobium film on copper samples are presented. Different models accounting for the field depended surface resistance are being confronted by the experimental results. The RF results are being correlated to surface analyses measurements carried out on the same samples.

WEPPC041	Tests of SRF Deflecting Cavities at 2K	cavity, SRF, vacuum, cryogenics	2300
	J.D. Fuerst, D. Horan, J. Kaluzny, A. Nassiri, T.L. Smith, G. Wu ANL, Argonne, USA
	Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract No. DE-AC02-06CH11357. The Advanced Photon Source (APS) at Argonne National Laboratory (ANL) is developing 2.8-GHz deflecting-mode superconducting rf cavities in collaboration with Jefferson Lab as part of a major facility upgrade. On-site testing of these cavities requires a new cryostat capable of operation at 2.0 K or less. The APS has leveraged facilities and expertise within ANL’s Physics Division to upgrade an existing test stand for continuous operation at temperatures as low as 1.7 K. A new cryogenic feedbox was fabricated and mated to an existing liquid helium “bucket” dewar with 0.6-m inside diameter and 1-m working depth. The configuration allows continuous sub-λ operation using warm vacuum pumping and helium make-up from the Physics Division’s existing cryoplant at heat loads up to 50 W dynamic, plus 15 W measured static load at 2.0 K. A 2.8-GHz TWT-based rf station has been installed and commissioned, providing up to 275 W of rf power. We describe the cryogenic and rf performance of the system and provide examples of cavity test results.

WEPPD019	Manufacturing and Welding Process of Straight Section of Aluminum Alloy UHV Chambers for Taiwan Photon Source	vacuum, synchrotron, radiation, synchrotron-radiation	2537
	C.-C. Chang, C.K. Chan, C.L. Chen, J.-R. Chen, G.-Y. Hsiung, S-N. Hsu NSRRC, Hsinchu, Taiwan
	This paper describes the manufacturing process and welding sequence for the aluminum extrusion vacuum chamber for the straight sections in Taiwan Photon Source. The straight section composes of aluminum extrusion chamber of A6063 and BPM chamber of A6061 aluminum alloys. The straightness and flatness of these extrusion chambers are controlled under 0.1mm/m and 0.2mm/m, respectively. The BPM chambers are manufactured precisely in oil-free environment, which provide clean surface and a precise sealing surface after machining. All the components are assembled in pre-aligned support system through the welding process. The aluminum chamber for 24 straight sections has been welded. The results show the straightness of < 0.15mm/m, flatness of < 0.3mm/m, and leakage rates of < 2 × 10^-10 mbarl/sec. were achieved.

WEPPD021	Optimization of the Ultra-High Vacuum Systems for the 3 GeV TPS Synchrotron Light Source	vacuum, impedance, electron, synchrotron	2543
	G.-Y. Hsiung, C.K. Chan, C.-C. Chang, C.L. Chen, J.-R. Chen, C.M. Cheng, Y.T. Cheng, S-N. Hsu, H.P. Hsueh, Huang, Y.T. Huang, I.C. Sheng, L.H. Wu, Y.C. Yang NSRRC, Hsinchu, Taiwan
	The Taiwan Photon Source (TPS), a 3 GeV synchrotron light source, provides an ultra-low emittance of electron beam and the consequent extremely high brightness of photons. The vacuum pressure along the beam duct should be ultra-high vacuum (UHV) and even lower for reduction of the impact to the beam from the gas scattering or ion trapping troubles. Most of the outgas comes from the photon stimulated desorption (PSD) back streaming from downstream absorbers during beam operation and large area surface outgas inside the beam duct as well. Due to the anticipate request of the smallest vertical aperture of beam ducts from various insertion devices and the lowest broadband impedance through all the vacuum chambers of electron storage ring, the inner structure design and the surface treatment of vacuum chambers as well as the constraint of the back stream PSD outgas from distributed absorbers and the pumping locations should be optimized to obtain a high quality UHV system for the high stable synchrotron light source through the long period of operation. The optimized design of the vacuum chambers for the TPS will be described.

WEPPD022	Design of the Water-Cooling System for the Vacuum System of the TPS Storage Ring	vacuum, synchrotron, storage-ring, controls	2546
	Y.C. Yang, C.K. Chan, J.-R. Chen, C.M. Cheng, G.-Y. Hsiung NSRRC, Hsinchu, Taiwan
	Taiwan Photon Source (TPS) was under construction since 2009. TPS vacuum system was designed in 10^-10 torr level and gas load from synchrotron light was almost confined in bending chambers. A water cooling system was designed to protect vacuum equipment including vacuum chambers and absorbers to avoid melting down by synchrotron light. There are 3 cooling loops for aluminum chambers and 4 loops for cooper absorbers in one unit cell. One prototype for unit cell, including arrangement of control terminal, monitor of flow rate and temperature, and vibration from cooling system will be tested.

WEPPD024	A Study of Vacuum Pressure in TPS Cells	vacuum, site, electron, controls	2552
	L.H. Wu, J.-R. Chen, C.M. Cheng, G.-Y. Hsiung, C.S. Huang, Huang, Y.T. Huang NSRRC, Hsinchu, Taiwan
	Recently, the type-2 and type-3 TPS cells are installed and pumped down into vacuum status. The pumping down curves of the type-2 and type-3cells, including R03, R06, R07, R10, and R11, are recorded after on-site welding and after assembling without leakage, individually. In the R03, R06, R07, R10 cells, the pumping down curve after assembling without leakage is a little higher than that after on-site welding. In those four cells, the pumping down curve after assembling all vacuum components and pumps is similar. However, in the R11 cell, it was found that the pumping down curve after assembling without leakage is almost along that of after on-site welding. The slope of pumping down curve near 1 hour in the R11 cell is -1.52, while that in the R10 cell is -1.39. It means that the vacuum pressure in the R11 cell is apparently improved. It is confirmed that the vacuum chambers are cleaned by the same process and the assembling components are similar. Besides, the photon stopper chambers are all pre-baked to 200 oC for the same time. We try to investigate the residual gas analysis (RGA) data to find the true reasons.

WEPPD026	Design and Fabrication of NSLS-II Storage Ring Vacuum Chambers and Components	vacuum, storage-ring, multipole, impedance	2558
	H.-C. Hseuh, A.T. Anderson, L. Doom, M.J. Ferreira, C. Hetzel, C. Longo, V. Ravindranath, K. Roy, S.K. Sharma, J.L. Tuozzolo, K. Wilson BNL, Upton, Long Island, New York, USA
	Funding: Work performed under the auspices of U.S. Department of Energy, under contract DE-AC02-98CH10886 The National Synchrotron Light Source II, a 3-GeV, 792-meter circumference, synchrotron radiation facility with ultra-high-flux and brightness, is under construction at Brookhaven National Laboratory. The storage ring vacuum chambers are mainly made of extruded aluminium but with a few made of stainless steel and inconel. The synchrotron radiation from bending magnets is intercepted at discrete photon absorbers made of GlidCop. NEG strips in the ante-chamber provide the distributed pumping, while lumped ion pumps and titanium sublimation pumps at photon absorbers remove the desorbed gas. The complex vacuum system is being assembled and integrated in-house. This paper describes the design and fabrication of both standard and special vacuum chambers, the low impedance RF shielded bellows and the photon absorbers. The vacuum system is now moving into the conditioning, installation and testing phase. Details and experience from the large scale production, testing and lesson learned will also be presented.

WEPPD032	Heat Load Studies in Target and Collimator Materials for the ILC Positron Source	positron, polarization, undulator, target	2576
	F. Staufenbiel, S. Riemann DESY Zeuthen, Zeuthen, Germany O.S. Adeyemi, V.S. Kovalenko, L.I. Malysheva, G.A. Moortgat-Pick, A. Ushakov University of Hamburg, Hamburg, Germany
	An intense polarized positron beam for future linear colliders can be produced using a high power beam of circularly polarized photons which penetrates a thin titanium-alloy target. The degree of polarization can be increased by cutting the outer part of the photon beam generated in a helical undulator using a collimator in front of the target. However, the photon beam induces substantial heat load and stress inside the target and collimator materials. In order to avoid failure of these components the stress evolution has been simulated. The results as well as the corresponding material arrangements for the photon collimator design are presented.

WEPPD041	The Strategy between High Precision Temperature Control and Energy Saving for Air-Conditioning System	controls, monitoring, target, feedback	2603
	Z.-D. Tsai, W.S. Chan, J.-C. Chang, C.S. Chen, Y.-C. Chung, C.W. Hsu, C.Y. Liu NSRRC, Hsinchu, Taiwan
	In the Taiwan Light Source (TLS), several studies related to the temperature stability for air conditioning system continued to be in progress. Using new control philosophy can minimize temperature variations effectively. A high precision temperature control within ±0.05°C for air condition system has been conducted to meet the more critical stability requirement. Due to the importance of energy saving issue, the power consumption of air conditioning system was also upgraded and intended to reduce extensively. The paper addresses some experience between high precision temperature control and energy saving about operation of air conditioning system. The significant improvements proven that both targets can achieve simultaneously.

WEPPD045	An Application of Multi-stage Adjustable Shock Absorbers for the Girders of Storage Ring in Taiwan Photon Source	damping, acceleration, controls, storage-ring	2615
	C.-S. Lin, J.-R. Chen, M.L. Chen, H.C. Ho, K.H. Hsu, D.-G. Huang, C.K. Kuan, W.Y. Lai, C.J. Lin, H.M. Luo, S.Y. Perng, P.L. Sung, Y.L. Tsai, T.C. Tseng, H.S. Wang, M.H. Wu NSRRC, Hsinchu, Taiwan D.-Y. Chiang NCKU, Tainan city, Taiwan
	Beam stability is a major concern for the operation of the Taiwan Photon Source (TPS). One of the many factors to instability of electron beam is mechanical vibration of the accelerator components. The TPS uses steel girders to support the magnets and vacuum chambers in the storage ring. Three pedestal and six mover assemblies support the girders. Multi-stage adjustable shock absorbers are designed for passive vibration damping, and presently installed between the girders and the pedestals. Through adjusting the amount of hydraulic fluid which bypasses the damping passage between two hydraulic chambers, the desired damping coefficient of the damping absorbers can be achieved. Experimental results of modal testing presented in this paper show that the multi-stage adjustable damping absorbers under the assembly of the girders reduced the level of girder vibration.

WEPPD055	Gamma-rays Generation with 3D 4-mirror Cavity for ILC Polarized Positron Source	cavity, laser, electron, scattering	2645
	T. Akagi, S. Miyoshi Hiroshima University, Graduate School of Advanced Sciences of Matter, Higashi-Hiroshima, Japan S. Araki, Y. Funahashi, Y. Honda, T. Okugi, T. Omori, H. Shimizu, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan H. Kataoka, T. Kon Seikei University, Japan M. Kuriki, T. Takahashi Hiroshima University, Graduate School of Science, Higashi-Hiroshima, Japan K. Sakaue, M. Washio RISE, Tokyo, Japan R. Tanaka, H. Yoshitama Hiroshima University, Higashi-Hiroshima, Japan
	We are conducting gamma-rays generation experiment by the laser-Compton scattering using a Fabry-Perot cavity. We developed a 3D 4-mirror cavity, and it is installed at the KEK-ATF. By using a 3D 4-mirror cavity, small laser spot can be achieved with stable resonant condition. In addition, we aim 1900 times enhancement of input laser power by a 4-mirror cavity to increase the number of gamma-rays.

WEPPD061	Quality Control of Modern Linear Accelerator: Dose Stability Long and Short-term	controls, radiation, factory, monitoring	2660
	T.U. Uddin NICRH, Dhaka, Bangladesh
	Quality Control (QC) data of modern linear accelerators, collected by National Institute of Cancer Research and Hospital, Dhaka, Bangladesh between the years 2006 and 2010, were analyzed. The goal was to provide information for the evaluation and elaboration of QC of accelerator outputs and to propose a method for QC data analysis. Short- and long-term drifts in outputs were quantified by fitting empirical mathematical models to the QA measurements. Normally, long-term drifts were well (≤1.5%) modeled by either a straight line or a single-exponential function. A drift of 2% occurred in 18 ± 12 months. The shortest drift times of only 2–3 months were observed for some new accelerators just after the commissioning but they stabilized during the first 2–3 years. The short-term reproducibility and the long-term stability of local constancy checks, carried out with a sealed plane parallel ion chamber, were also estimated by fitting empirical models to the QC measurements. The reproducibility was 0.3–0.6% depending on the positioning practice of a device. Long-term instabilities of about 0.3%/month were observed for some checking devices.

WEPPP017	Recent Results at the SPARC_LAB Facility	laser, electron, plasma, injection	2758
	M. Ferrario, D. Alesini, M.P. Anania, M. Bellaveglia, R. Boni, M. Castellano, E. Chiadroni, G. Di Pirro, A. Drago, A. Esposito, A. Gallo, C. Gatti, G. Gatti, A. Ghigo, T. Levato, E. Pace, L. Pellegrino, R. Pompili, A.R. Rossi, B. Spataro, P. Tomassini, C. Vaccarezza, F. Villa INFN/LNF, Frascati (Roma), Italy A. Bacci, C. De Martinis, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy G. Dattoli, E. Di Palma, L. Giannessi, A. Petralia, M. Quattromini, C. Ronsivalle, I.P. Spassovsky, V. Surrenti ENEA C.R. Frascati, Frascati (Roma), Italy D. Di Giovenale INFN-Roma II, Roma, Italy U. Dosselli INFN, Roma, Italy R. Faccini INFN-Roma, Roma, Italy R. Fedele Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli, Italy M. Gambaccini INFN-Ferrara, Ferrara, Italy D. Giulietti UNIPI, Pisa, Italy L.A. Gizzi, L. Labate CNR/IPP, Pisa, Italy P. Londrillo INFN-Bologna, Bologna, Italy S. Lupi Università di Roma I La Sapienza, Roma, Italy A. Mostacci, L. Palumbo Rome University La Sapienza, Roma, Italy G. Passaleva INFN-FI, Sesto Fiorentino, Italy V. Petrillo Universita' degli Studi di Milano, Milano, Italy J.V. Rau ISM-CNR, Rome, Italy G. Turchetti Bologna University, Bologna, Italy
	A new facility named SPARC_LAB (Sources for Plasma Accelerators and Radiation Compton with Lasers and Beams) has been recently launched at the INFN National Labs in Frascati, merging the potentialities of the old projects SPARC and PLASMONX. The SPARC project, a collaboration among INFN, ENEA and CNR, is now completed, hosting a 150 MeV high brightness electron beam injector which feeds a 12 meters long undulator. Observation of FEL radiation in the SASE, Seeded and HHG modes has been performed from 500 nm down to 40 nm wevelength. A second beam line has been also installed to drive a narrow band THz radiation source. In parallel to that, INFN decided to host a 300 TW laser that will be linked to the linac and devoted to explore laser-matter interaction, in particular with regard to laser-plasma acceleration in the self injection and external injection modes, (the PLASMONX experiments). The facility will be also used for particle driven plasma acceleration experiments (the COMB experiment). A Thomson scattering experiment coupling the electron bunch to the high-power laser to generate coherent monochromatic X-ray radiation is also in the commissioning phase.

WEPPP027	PBG-slab Embedded Traveling Wave Structure for Planar Beam Accelerator Application	electron, HOM, acceleration, lattice	2784
	Y.-M. Shin Fermilab, Batavia, USA
	The oversized traveling wave (TE10-mode) channel integrated with the photonic-band-gap (PBG) slab arrays have been investigated for planar beam accelerator application. Simulation analysis showed that the slab arrays allow only the PBG-modes (5-6 GHz) to propagate with ~ 2 dB of insertion loss, corresponding to ~ 1.14 dB/cm attenuation, which thereby effectively suppresses trapped non-PBG modes down to ~ -14.3 dB/cm. It will enable monochromatic propagation of fundamental acceleration modes along the heavily over-moded planar waveguide without anomalous excitation of unstable trapped HOMs. The saturated maximum field gradients of the accelerating structure have been analyzed with respect to operational frequency bands corresponding to structural sizes. The field gradient of the guided PBG-mode has been investigated with finite-integral-method (FIM) simulations at W-band. This mode-filter could be utilized for HOM dampers in high aspect ratio (HAR) planar beam accelerators. An experimental test is currently under consideration.

WEPPP067	Commissioning Results of Slow Orbit Feedback using PID Controller Method for the Siam Photon Source	feedback, controls, storage-ring, LabView	2861
	S. Klinkhieo, S. Boonsuya, P. Klysubun, S. Krainara, P. Songsiriritthigul, P. Sudmuang, N. Suradet SLRI, Nakhon Ratchasima, Thailand S. Rujirawat Suranaree University of Technology, Nakhon Ratchasima, Thailand
	A slow orbit feedback (SOFB) system has been developed to improve the orbit stability for the storage ring of the Siam Photon Source (SPS). The SOFB uses a PID controller method utilizing LabVIEW channel to access 20 BPMs and 28 correctors of the storage ring. The first phase implementation of the feedback loops based on this method was operated at 0.05Hz of sampling frequency, which reduce the fluctuation of both horizontal and vertical positions of the orbit from ~200 microns down to ~30 microns. The commissioning results indicate that further work and hardware upgrade are required. A higher sampling frequency at least 30Hz is strongly required for PID controller implementation. Upgrading of the existing 12-bit resolution corrector power supplies is also necessary. The basic principle of PID algorithms, hardware, software and commissioning results of the current SOBF system, as well as a future development plan, will be presented.

WEPPP069	Performance Enhancements for the Transverse Feedback System at the Advanced Photon Source	feedback, EPICS, storage-ring, controls	2867
	N.P. Di Monte, R.I. Farnsworth, A.J. Scaminaci ANL, Argonne, USA
	With the success of the transverse feedback system at the Advanced Photon Source (APS), an upgrade to this system is being developed. The current system is operating at a third of the storage ring bunch capacity, or 324 of the available 1296 bunches. This upgrade will allow the sampling of all 1296 bunches and make corrections for all selected bunches in a single storage ring turn. To facilitate this upgrade, a new analog I/O board capable of 352-MHz operation is being developed along with a P0 bunch cleaning circuit. The clock cleaning circuit is also needed for the high speed analog output circuit, which is transmitted about 200 m to a separate DAC unit in real time. This remote DAC will have its transceiver data rate triple from 2.3 Gb to about 7 Gb on a fiber optic link. This paper will discuss some of the challenges in reducing the clock jitter from the system P0 bunch clock along with the necessary FPGA hardware upgrades and algorithm changes, all of which are required for the success of this upgrade.

WEPPP071	Phase Noise Studies at the Advanced Photon Source	simulation, storage-ring, synchrotron, feedback	2873
	N. Sereno, G. Decker, R.M. Lill, B.X. Yang ANL, Argonne, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. Phase noise generated primarily by power line harmonics modulating the 352-MHz rf system in the APS storage ring is a dominant source of high- frequency beam motion, both longitudinally and transversely, due to dispersion in the lattice. It also places fundamental limits on the ability to generate picosecond-scale x-ray pulses for fast pump / probe experiments. Measurements using turn-by-turn beam position monitors (BPMs) located at high-dispersion locations are compared and contrasted with results from a dedicated S-band phase detector connected to either a capacitive pickup electrode or a diamond x-ray detector. Horizontal beam position at high-dispersion locations is related directly to beam phase by a very simple relation involving the momentum compaction. Simulation results are used to validate this relationship and to quantify the relation between phase noise on the main rf vs beam arrival time jitter. A. Zholents et al., NIM A 425, 385 (1999).

WEPPP088	Auto-alignment System and CalibrationPprocedure in TPS Girder System	alignment, laser, survey, storage-ring	2918
	W.Y. Lai, J.-R. Chen, M.L. Chen, H.C. Ho, K.H. Hsu, D.-G. Huang, C.K. Kuan, C.-S. Lin, C.J. Lin, H.M. Luo, S.Y. Perng, P.L. Sung, Y.L. Tsai, T.C. Tseng, H.S. Wang, M.H. Wu NSRRC, Hsinchu, Taiwan
	The TPS (Taiwan photon source) project is under construction and will be finished in the December 2012. Considering the floor’s deformation with time and frequent earthquakes at Taiwan, the survey and alignment procedure should be taken quite often. For dealing with these difficulties and improving accuracy of girder’s position, a highly accurate auto-tuning girders system was designed to accomplish the alignment tasks. There are two cells of TPS girders and varied sensor modulus set up for testing the auto-tuning system. The adjustment of the system converges to less than 6um, and the repeatability of the testing is under 10 um. For improving the accuracy of girders position, that is critical thing to make sure all the calibration of sensors modulus correctly and accurately. The calibration procedure about sensor modular and testing results is described in this paper.

WEPPP095	Digital Pulse Processor for High Demanding Synchrotron Spectroscopy	EPICS, controls	2929
	S. Bucik, A. Bardorfer, B.B. Baricevic, R. Hrovatin, E. Janezic, B. Repič, D. Škvarč I-Tech, Solkan, Slovenia M. Vencelj JSI, Ljubljana, Slovenia
	The availability of brighter synchrotorn X-ray sources enable more complex experiments, such as 2D or 3D X-mapping. All the electrical signals generated in scmiconductive detectors are then processed and analysed by fast digital pulse processors (DPP). The poster presents the state of the art DPP currently in development by Instrumentation Technologies . We will discuss the signal transformation and processing from the detector preamplifier output to the final result: energy histogram and time stamped list mode. The signal processing chain starts with signal conditioning of the analog input signal. After the ADCs transformation, all the signal processing in the digital domain is done in FPGA. To each measured pulse a time-stamp is applied. Libera BASE FDK enables customer specific algorithms to be included in the FPGA.

THYA02	Ultracompact Accelerator Technology for a Next-generation Gamma-Ray Source	gun, klystron, laser, electron	3190
	R.A. Marsh, F. Albert, S.G. Anderson, C.P.J. Barty, D.J. Gibson, F.V. Hartemann, S.S.Q. Wu LLNL, Livermore, California, USA
	Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. This presentation will report on the technology choices and progress manufacturing and testing the injector and accelerator of the 250 MeV ultra-compact Compton Scattering X-ray Source under development at LLNL for homeland security applications.
	Slides THYA02 [12.896 MB]

THEPPB008	Inverse Compton Scattering Experiment in a Bunch Train Regime Using Nonlinear Optical Cavity	laser, electron, cavity, linac	3245
	A.Y. Murokh, R.B. Agustsson, S. Boucher, P. Frigola, T. Hodgetts, A.G. Ovodenko, M. Ruelas, R. Tikhoplav RadiaBeam, Santa Monica, USA M. Babzien, M.G. Fedurin, T.V. Shaftan, V. Yakimenko BNL, Upton, Long Island, New York, USA I. Jovanovic Penn State University, University Park, Pennsylvania, USA
	Inverse Compton Scattering (ICS) is a promising approach towards achieving high intensity, directional beams of quasi-monochromatic gammas, which could offer unique capabilities in research, medical and security applications. Practicality implementation of ICS sources, however, depends on the ability to achieve high peak brightness (~0.1-1.0 ICS photons per interacting electron), while increasing electron-laser beam interaction rate to about 10,000 cps. We discuss the results of the initial experimental work at the Accelerator Test Facility (ATF) at BNL to demonstrate ICS interaction in a pulse-train regime, using a novel laser recirculation scheme termed Recirculation Injection by Nonlinear Gating (RING). Initial experimental results and outlook are presented.

THEPPB012	Pressure Acoustic Waves in Positron Production Targets for Future Lepton Colliders	target, positron, collider, linear-collider	3257
	O.S. Adeyemi, V.S. Kovalenko, L.I. Malysheva, G.A. Moortgat-Pick, A. Ushakov University of Hamburg, Hamburg, Germany A.F. Hartin DESY, Hamburg, Germany F. Staufenbiel DESY Zeuthen, Zeuthen, Germany
	Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE Future high energy lepton colliders demand high luminosities to achieve its physics goals. For the electron-positron linear collider, the generation of positrons is a non-trivial problem: the positron production target has to a survive huge amount of energy deposited by the bombardment of intense beams of electrons or photons. This causes a rapid increase of the temperature in the target within a very short time period. The resulting thermal stress induces pressure waves and can substantially shorten the operating life-span of for the target material. In this work, we study linear and effects of induced stress through pressure acoustic waves using a hydrodynamic model. The survivability issue of the target is discussed.

THPPC021	A Microwave Paraphoton and Axion Detection Experiment with 300 dB Electromagnetic Shielding at 3 GHz	cavity, shielding, coupling, pick-up	3320
	M. Betz, F. Caspers CERN, Geneva, Switzerland
	Funding: Work supported by the Wolfgang-Gentner-Programme of the Bundesministerium für Bildung und Forschung (BMBF). For the microwave equivalent of "light shining through the wall" (LSW) experiments, a sensitive microwave detector and very high electromagnetic shielding is required. The screening attenuation between the axion-generating cavity and the nearby detection-cavity should be greater than 300 dB, in order to push beyond the presently existing exclusion limits. To achieve these goals in practice, a "box in a box" concept was utilized for shielding the detection-cavity, while a vector signal analyzer was used as a microwave receiver with a very narrow resolution bandwidth in the order of a few micro-Hz. This contribution will present the experimental layout and show the results to date.

THPPD063	Zero Voltage Switching of Two-switch Flyback-Forward Converter	synchrotron, synchrotron-radiation, radiation, power-supply	3656
	J.C. Huang, K.-B. Liu, Y.S. Wong NSRRC, Hsinchu, Taiwan
	The traditional pulse-width-modulated flyback converter power switch has serious electromagnetic interference (EMI) and lower conversion efficiencies problems due to the hard-switching operations. This paper produces a zero voltage switching of flyback-forward converter with an active-clamp circuit, the traditional pulse-width-modulated flyback converter with a active clamp circuit to achieve zero-voltage-switching (ZVS) at both main and auxiliary switches, the active-clamp circuit can reduce most of switching loss and voltage spikes across the switches and improve the overall efficiency of the converter. The theoretical analysis of soft switching flyback-forward converter with an active-clamp circuit is verified exactly by a prototype of 50W with 100V input voltage, 5V output voltage and 30kHz operated frequency.

THPPR002	The Undulator Control System for the European XFEL	undulator, controls, quadrupole, electron	3966
	S. Karabekyan, A. Beckmann, J. Pflüger European XFEL GmbH, Hamburg, Germany N. Burandt, J. Kuhn Beckhoff Automation GmbH, Verl, Germany A. Schöps DESY, Hamburg, Germany
	The European XFEL project is a 4th generation light source. The first beam will be delivered in the beginning of 2015 and will produce spatially coherent ≤80fs short photon pulses with a peak brilliance of 10³²–10³⁴ photons/s/mm²/mrad²/0.1% BW in the energy range from 0.26 to 29 keV at electron beam energies of 10.5 GeV, 14 GeV, or 17.5 GeV . The Undulator systems are used to produce photon beams for SASE 1, SASE 2 and SASE 3. Each undulator system consists of an array of undulator cells installed in a row along the electron beam. A single undulator cell itself consists of a planar undulator, a phase shifter, magnetic field correction coils and a quadrupole mover. This paper describes the design of the entire undulator control system including local and global control. It presents a concept of integration of the undulator control into the accelerator control system as well as into the experiment control.

THPPR022	Radiation Dose Simulation and Measurement plan for SSRF Beam Lines by Using ATOM Phantoms	neutron, radiation, simulation, synchrotron	4008
	Y. Sheng, L.X. Liu, X. Xia, J.Q. Xu SINAP, Shanghai, People's Republic of China
	Radiation dose assessment in advanced synchrotron radiation facility is challenging due to the complexity and uncertainties of radiation source terms induced by high energy particle accelerator. Shanghai Synchrotron Radiation Facility, SSRF, is the first third-generation synchrotron facility in China, which was completed in 2009. Radiation dose assessment for workers at SSRF Beam lines is highly concerned. This study presents the dose simulation with Monte Carlo method. The dose simulation was performed with a hybrid phantom coupled into MCNPX code. The hybrid phantom was constructed by combining the ATOM phantom and the Voxel-based Chinese Reference female Phantom, VCRP-woman, originally developed by using the high resolution color photographs. The organs absorbed dose calculated for photon and neutron were compared. An Experiment of measuring the organs dose by using the ATOM phantom will be performed in the near future.

THPPR042	Optimisation of an Inverse Compton Scattering Experiment with a Real Time Detection Scheme Based on a Radio Luminescent Screen and Comparison of the X-rays Beam Characteristics with Simulations	electron, laser, emittance, scattering	4068
	A.S. Chauchat, JP. Brasile TCS, Colombes, France A. Binet, V. Le Flanchec, J-P. Nègre CEA/DAM/DIF, Arpajon, France J.-M. Ortega LCP/CLIO, Orsay, Cedex, France
	To optimize the detection of an 11-keV X-Ray beam produced by Inverse Compton Scattering at the ELSA facility, with a 17 MeV electron beam and a 532 nm laser, we demonstrate the use of a very sensitive detection scheme, based on a radio luminescent screen used in the spontaneous emission regime. It has proven to be very sensitive and very effective to detect 11-keV X-Rays while rejecting the overall ambient noise produced in a harder spectral range. It allowed us to optimize the electron-photon interaction probability by observing in real time the effect of both beams transport parameters. We could then compare simulation results with experimental measurements that appear to be in good agreement. A.S. Chauchat et al. Instrumentation developments for production and characterization of Inverse Compton Scattering X-rays and first results with a 17 MeV electron beam, NIMA, V.622, I.1, P.129-135

THPPR065	High Flux Laser-Compton Scattered Gamma-ray Source by Compressed Nd:YAG Laser Pulse.	laser, electron, microtron, resonance	4124
	I. Daito, R. Hajima, T. Hayakawa, Y. Hayashi, M. Kando, H. Kotaki, T. Shizuma JAEA, Kyoto, Japan H. Ohgaki Kyoto University, Institute for Advanced Energy, Kyoto, Japan
	A non-destructive detection system of nuclear materials hidden in cargo containers is under development in Japan Atomic Energy Agency and Kyoto University. The system is able to be used for the identification of isotopes of special nuclear material in a container by employing Nuclear Resonance Fluorescence triggered by mono-energetic Laser Compton Scattered (LCS) gamma-ray tuned at the energy of the nuclear resonance. One of the most important technologies for such system is generation of gamma-rays at a flux of 3 x10⁵ photon/s. In order to achieve this gamma-ray flux with a compact system, a pulse compression system for Nd:YAG laser based on Stimulated Brillouin Scattering (SBS) has been developed. The laser pulse with a duration of 10 ns (FWHM) from a commercially available Nd:YAG laser is compressed down to a few hundreds ps. As a feasibility study of the proposed system, 400 keV gamma-ray generation is performed at Kansai Photon Science Institute by using 150 MeV electron beam from microtron accelerator and compressed Nd:YAG laser. Experimental results of laser pulse compression and gamma-ray generation are presented.

THPPR068	Laser Compton Scattering X-rays as a Tool for K-edge Densitometry	laser, electron, scattering, radiation	4133
	M. Titberidze, K. Chouffani IAC, Pocatello, IDAHO, USA
	There is a huge interest in bright and tunable X-ray sources. These sources can be used in various research fields, including medical, biological and industrial fields. Laser Compton Scattering (LCS) technique gives us possibility to generate tunable, quasi monochromatic and polarized X-ray beam. One of the applications of LCS is the detection and quantitative identification of special nuclear materials (SNM) using K-edge densitometry(KED)method. Our group was the first one who has used a quasi-monochromatic LCS source to carry out KED experiments. The experiments showed that LCS technique could be used for SNM detection and quantification.

THPPR070	Development of Multi-collision Laser Compton Scattering X-ray Source on the Basis of Compact S-band Electron Linac	laser, electron, cavity, linac	4139
	R. Kuroda, M. Koike, E. Miura, Y. Taira, H. Toyokawa, K. Yamada, E. Yamaguchi AIST, Tsukuba, Ibaraki, Japan M. Kumaki RISE, Tokyo, Japan
	A compact hard X-ray source via laser Compton scattering is required for biological, medical and industrial science because it has many benefits about generated X-rays such as short pulse, quasi-monochromatic, energy tunability and good directivity. Our X-ray source is conventionally the single collision system between an electron pulse and a laser pulse. To increase X-ray yields, we have developed a multi-collision system with a multi-bunch electron beam and a laser optical cavity. The multi-bunch electron beam has already been generated from a Cs-Te photocathode rf gun system using a multi-pulse UV laser. The laser optical cavity have developed like a regenerative amplification including the collision point between the electron pulse and the laser pulse which is based on the Ti:Sa laser with a mode-locked frequency of 79.33 MHz. In this preliminary experiment, the modulated seed laser pulses were generated and leaded to the cavity, so that laser build-up amplification was performed in the cavity length of 3.78 m with two seed pulses. In this conference, we will describe the results of preliminary experiments for the multi-collision system and future plans.

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MOEPPB010

Measurement of Satellite Bunches at the LHC

emittance, synchrotron, ion, coupling

97

A. Jeff, M. Andersen, A. Boccardi, S. Bozyigit, E. Bravin, T. Lefèvre, A. Rabiller, F. Roncarolo
CERN, Geneva, Switzerland
A.S. Fisher
SLAC, Menlo Park, California, USA
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: Adam Jeff is a DITANET fellow, supported by the EU's Marie Curie actions contract PITN-GA-2008-215080.
The RF gymnastics involved in the delivery of proton and lead ion bunches to the LHC can result in satellite bunches of varying intensity occupying the nominally empty RF buckets. Quantification of these satellites is crucial for bunch-by-bunch luminosity normalization as well as for machine protection. We present an overview of the longitudinal density monitor (LDM) which is the principal instrument for the measurement of satellite bunches in the LHC. The LDM uses single photon counting of synchrotron light. The very high energies reached in the LHC, combined with a dedicated undulator for diagnostics, allow synchrotron light measurements to be made with both protons and heavy ions. The arrival times of photons are collected over a few million turns, with the resulting histogram corrected for the effects of the detector’s deadtime and afterpulsing in order to reconstruct the longitudinal profile of the entire LHC ring. The LDM has achieved a dynamic range in excess of 10⁵ and a time resolution of 90 ps. Example results are presented and the measurements are benchmarked against satellite distributions based on collision data from the LHC experiments.

MOPPC001

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

electron, simulation, dipole, injection

115

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

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

MOPPC052

Calculation of Synchrotron Radiation from High Intensity Electron Beam at eRHIC

radiation, electron, synchrotron, vacuum

247

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

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

MOPPP004

Further Study on Fast Cooling in Compton Storage Rings

laser, electron, storage-ring, simulation

571

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

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

MOPPP008

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

laser, electron, scattering, background

583

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

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

MOPPP009

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

scattering, simulation, target, laser

586

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

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

MOPPP029

Photocathodes at FLASH

cathode, electron, gun, laser

625

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

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

MOPPP062

Soleil Emittance Reduction using a Robinson Wiggler

emittance, brightness, damping, wiggler

702

H.B. Abualrob, P. Brunelle, M.-E. Couprie, O. Marcouillé, A. Nadji, L.S. Nadolski, R. Nagaoka
SOLEIL, Gif-sur-Yvette, France

For both synchrotron light sources as SOLEIL and colliders, the emittance is one of the key parameters to increase the photon brightness and the beam luminosity. In order to decrease the emittance, the ring optics is built on very focusing lattices leading to large chromaticities and potential reduction of the dynamics aperture and momentum transverse acceptance. Thus, some facilities have installed damping wigglers in zero dispersion straight sections to relax the optics and to reach sub-nanometer horizontal emittances. This solution requires however tens or hundreds meters of insertion devices. For storage ring equipped with zero-gradient bending magnets, an alternative solution can be given by installing a single Robinson wiggler [1] in a dispersive section enabling to divide the emittance by a factor 2. The uniqueness of this wiggler results from the presence of an alternated gradient superimposed the main periodic magnetic field. This paper recalls the concept of the wiggler, presents the expected gain for SOLEIL storage ring with the impact on the linear optics and the brightness. A preliminary magnetic design is also proposed. [1] K.W. Robinson, Phys. Rev, p. 373 (1958).

MOPPP065

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

undulator, simulation, status, electron

708

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

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

MOPPP072

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

undulator, radiation, polarization, electron

729

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

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

MOPPP078

Status of the First Planar Superconducting Undulator for the Advanced Photon Source

undulator, controls, status, radiation

744

Y. Ivanyushenkov, M. Abliz, K.D. Boerste, T.W. Buffington, C.L. Doose, J.D. Fuerst, Q.B. Hasse, M. Kasa, S.H. Kim, R. Kustom, E.R. Moog, D. Skiadopoulos, E. Trakhtenberg, I. Vasserman
ANL, Argonne, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Superconducting technology offers the possibility of building short-period undulators for synchrotron light sources. Such undulators will deliver higher fluxes at higher photon energies to the light source user community. The Advanced Photon Source (APS) team is building the first superconducting planar undulator to be installed in the APS storage ring. The current status of the project is presented in this paper.

MOPPP090

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

undulator, electron, vacuum, radiation

765

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

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

MOPPR007

Investigation of Techniques for Precise Compton Polarimetry at ELSA

electron, polarization, laser, simulation

783

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

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

MOPPR016

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

electron, diagnostics, SRF, laser

810

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

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

MOPPR034

A Laser Wire System at Electron Beam Transport Line in BEPCII

laser, electron, positron, simulation

852

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

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

MOPPR046

CLIC Luminosity Monitoring

simulation, luminosity, monitoring, background

885

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

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

MOPPR050

Design and Analysis of EPU XBPM in TPS

undulator, synchrotron, synchrotron-radiation, radiation

894

A. Sheng, C.M. Cheng, C.K. Kuan
NSRRC, Hsinchu, Taiwan
D. Shu
ANL, Argonne, USA

Several planer and elliptical polarized undulators (EPU) beam lines have been proposed and are to be built for Taiwan Photon Source (TPS) in National Synchrotron Research Center (NSRRC). Due to its complexity, with changing of vertical as well as horizontal deflection parameters (Kx and Ky), one finds that regular diamond bladed photon beam position monitor (XBPM) would not be sufficient to detect the center location of the undulator. A new conceptual design of EPU XBPM has been analyzed both in thermal as well as photon aspects. A prototype by taking advantage of fluorescent some of the diamond detectors has been designed and implemented in Taiwan Light Source (TLS) for testing. Some analysis and design scenarios are presented in this paper.

MOPPR053

Improvement of BPM System for the Siam Photon Source

storage-ring, shielding, synchrotron, controls

903

P. Songsiriritthigul, S. Boonsuya, S. Klinkhieo, P. Klysubun, S. Krainara, P. Sudmuang, N. Suradet
SLRI, Nakhon Ratchasima, Thailand
J.-R. Chen, H.P. Hsueh, Y.-H. Liu
NSRRC, Hsinchu, Taiwan
S. Rujirawat, P. Songsiriritthigul
Suranaree University of Technology, Nakhon Ratchasima, Thailand

The Siam Photon Source (SPS) is the first synchrotron light source ever built by modifying and relocating a light source from one country to another. The SPS produced its first light in Dec 2001. The machine has been used to provide regularly synchrotron light for users since 2005. Systematic studies and investigations of the machine have properly been carried out under the supervision of the International Advisory Committee of SLRI in the last two years. This report describes the improvement of the beam position monitoring (BPM) system for the 1.2 GeV storage ring of SPS. The efficiency and reliability of the original BPM system was greatly hindered by the low quality signal cables. The replacement with the higher quality (lower loss and better interference shielding) BPM cables and the implementation of a separated cable tray for the BPM cables have significantly improved the quality of the BPM signals, allowing the possibilities for machine study and thus providing further improvement of the machine. Detailed descriptions of the work on the BPM electronic boards will be described. The measurement results before and after the improvement of the BPM system will also be presented.

MOPPR054

Beam Size Measurement at Siam Photon Source Storage Ring

synchrotron, storage-ring, monitoring, radiation

906

P. Sudmuang, N. Deethae, P. Klysubun, S. Krainara, T. Poolampong, K. Sitisart, N. Suradet
SLRI, Nakhon Ratchasima, Thailand

Synchrotron radiation interferometer and direct imaging setups have been installed and subsequently utilized to investigate transverse beam profile at the Siam Photon Source (SPS). Details of the optical setup as well as the beam sizes determined from the measurement will be presented. Comparison between the measured and theoretical values as established by linear optics calibration will be made and discussed. In order to demonstrate the beam profiling capability of the interferometer and direct imaging systems, measurements with different operating parameters have been carried out and the results will be presented as well.

MOPPR067

Simulations of Fast X-ray Detectors Based on Multichannel Plates

electron, simulation, scattering, cathode

939

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

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

MOPPR090

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

electron, diagnostics, radiation, optics

996

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

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

TUOBB01

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

laser, electron, emittance, scattering

1086

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

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

Slides TUOBB01 [5.099 MB]

TUOBB03

Status of the FERMI@Elettra Project

FEL, laser, electron, radiation

1092

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

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

Slides TUOBB03 [5.316 MB]

TUEPPB009

First Measurements of the FACET Coherent Terahertz Radiation Source

radiation, electron, diagnostics, insertion

1134

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

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

TUPPC013

Optimization of Lower Emittance Optics for the SPring-8 Storage Ring

optics, emittance, lattice, brilliance

1182

Y. Shimosaki, K.K. Kaneki, M. Masaki, T. Nakamura, H. Ohkuma, J. Schimizu, K. Soutome, S. Takano, M. Takao
JASRI/SPring-8, Hyogo-ken, Japan

A design work of the present SPring-8 storage ring is in progress to improve its performance. The linear optics has been changed to reduce the natural emittance below the nominal of 3.4 nmrad at 8 GeV, and the nonlinear optics has been optimized with a genetic algorithm to suppress the amplitude-dependent tune shifts and to enlarge the dynamic aperture. As a preliminary study, the optics with the natural emittance of 2.4 nmrad at 8 GeV has been examined, theoretically and experimentally. In this optics, 1.5 times higher brilliance for 10 keV photons than the present can theoretically be expected for the standard undulator beamline. The improved optics design and its beam performance will be presented in detail. In this presentation, a optics for a future upgrade of the SPring-8 (SPring-8 II) will not be discussed, which is a full-scale major lattice modification, while the method we used in optimizing the nonlinear optics can also be adopted to the SPring-8 II*.
* Y. Shimosaki et al., "Design Study of Nonlinear Optics for a Very Low-emittance Lattice of the SPring-8 II," these proceedings.

TUPPC075

Study of Nonlinear Beam Dynamics Effects for DEPU at SSRF

polarization, undulator, electron, focusing

1347

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

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

TUPPD033

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

positron, target, dipole, electron

1476

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

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

TUPPD036

Novel Designs for Undulator Based Positron Sources

positron, target, undulator, damping

1485

M. Jenkins
Cockcroft Institute, Warrington, Cheshire, United Kingdom
I.R. Bailey, M. Jenkins
Lancaster University, Lancaster, United Kingdom

At least three proposed future colliders(ILC, CLiC and LHeC) require a positron source with a yield greater than 10¹⁴ e+/s. An undulator based positron source has the potential to provide the required yield. This design generates gamma rays by using a high energy electron beam traveling through a superconducting helical undulator. The gamma rays then pair produce in a titanium alloy target to produce positrons. This is the ILC baseline positron source. Two drawbacks to the undulator-based positron source are that it couples the positron source to the electron beam operation and that it exhibits a low conversion efficiency of photons to positrons. A self-seeding undulator-based positron source has been proposed. This starts with a low intensity positron beam which travels through the undulator to produce more positrons which are recirculated through the source to increase the intensity until the design yield is achieved. Multiple targets have been added to increase the conversion efficiency of the positron source. In this study I present simulation results for such a design and consider the feasibility of this design at the ILC, CLiC or LHeC.

TUPPD050

Investigation of Laser-cleaning Process on Lead Photocathodes

laser, electron, cathode, high-voltage

1515

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

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

TUPPD069

Schottky-Enabled Photoemission and Dark Current Measurements - Toward an Alternate Approach to Fowler-Nordheim Plot Analysis

gun, laser, site, cathode

1563

E.E. Wisniewski, W. Gai, J.G. Power
ANL, Argonne, USA
H. Chen, Y.-C. Du, Hua, J.F. Hua, W.-H. Huang, C.-X. Tang, L.X. Yan, Y. You
TUB, Beijing, People's Republic of China
A. Grudiev, W. Wuensch
CERN, Geneva, Switzerland
E.E. Wisniewski
Illinois Institute of Technology, Chicago, Illinois, USA

Field-emitted dark current, a major gradient-limiting factor in RF cavities, is usually analyzed via Fowler-Nordheim (FN) plots. Traditionally, field emission is attributed to geometrical perturbations on the bulk surface whose field enhancement factor (beta) and the emitting area (A) can be extracted from the FN plot. Field enhancement factors extracted in this way are typically much too high (1 to 2 orders of magnitude) to be explainable by either the geometric projection model applied to the measured surface roughness or by field enhancement factors extracted from Schottky-enabled photoemission measurements. We compare traditional analysis of FN plots to an alternate approach employing local work function variation. This is illustrated by comparative analysis of recent dark current and Schottky-enabled photoemission data taken at Tsinghua S-band RF gun. We conclude by describing a possible experimental plan for discrimination of variation of local work function vs. local field enhancement.

TUPPD070

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

cathode, electron, vacuum, wakefield

1566

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

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

TUPPD083

Raising Photoemission Efficiency with Surface Acoustic Waves

electron, polarization, linac, vacuum

1596

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

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

TUPPP004

Low-alpha Operation for the SOLEIL Storage Ring

optics, injection, coupling, radiation

1608

M.-A. Tordeux, J. Barros, A. Bence, P. Brunelle, N. Hubert, M. Labat, P. Lebasque, A. Nadji, L.S. Nadolski, J.-P. Pollina
SOLEIL, Gif-sur-Yvette, France
C. Evain
PhLAM/CERCLA, Villeneuve d'Ascq Cedex, France

The low momentum compaction factor (alpha) operation has been recently established on the SOLEIL Storage Ring. Both time resolved X-ray and THz radiation user communities are taking benefit from a hybrid filling pattern with a 4.7 ps RMS bunch length. At a value of 1.7 10^-5 (nominal alpha /25) and a current per bunch of 65 μA, stable THz radiation is produced in the range of 8 - 20 cm^-1 (measurements and comparison with Coherent Synchrotron Radiation (CSR) modeling are reported elsewhere*, **). Several low-alpha optics have been investigated and the optics presented at IPAC’11 has been selected for the operation. This paper presents the comprehensive experimental characterization of this optics. Specificities of the low-alpha operation, driven by the very demanding user experiments, are reviewed: closed orbit stability issues, extremely tight injected current step when refilling which implies a specific Linac tuning, low current diagnostics optimization, short bunch measurements, insertion devices effect on the CSR characteristics and radiation safety aspects justified by beam losses at injection.
* C. Evain, A. Loulergue et al., this conference.
** E. Roussel et al., this conference.

TUPPP017

Lattice Design of the SSRF Storage Ring with Superbend

lattice, emittance, dipole, optics

1644

S.Q. Tian, B.C. Jiang, H.H. Li, M.Z. Zhang, W.Z. Zhang, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

The SSRF storage ring is being investigated by upgrading with normal conducting superbend of 3 T. The bending magnets are shortened, and thus some additional straight sections with the length of about 2 m are created in the center of the arc cell. They can be used to install more insertion devices. The lattice adjustment and the optics design are presented in this paper, where much efforts are made to maintain the effective emittance along the ring with respect to the nominal optics.

TUPPP027

Subpicosecond Laser Slicing X-Ray Source for Time-resolved Research at TPS

wiggler, laser, emittance, lattice

1671

W.K. Lau, M.C. Chou, C.-S. Hwang, A.P. Lee, Y.-C. Liu, G.-H. Luo
NSRRC, Hsinchu, Taiwan
N.Y. Huang
NTHU, Hsinchu, Taiwan

The 3 GeV Taiwan Photon Source (TPS) under construction at NSRRC should be ready for user run in 2014. X-ray users in many research areas will then be benefited. However, there has been a growing interest in ultrafast time-resolved research in the island. The feasibility of using ultrafast laser for electron-beam slicing at TPS to produce sub-picosecond x-ray pulses is being investigated recently. The design and layout of a laser slicing scheme with W250 wiggler as the energy modulator in a 7 m medium straight section and EPU48 and IU22 radiators in other straight sections will be presented. It will offer the unique opportunity to gain experience in experimental techniques needed for FEL science.

TUPPP032

Use of Multi-objective Methods for Choosing Undulators for Storage Rings

brightness, undulator, target, storage-ring

1680

M. Borland
ANL, Argonne, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Users of storage ring light sources generally rely on undulators to provide the highest brightness. Choice of the optimal undulator period is complicated by the fact that users do not operate at a single photon energy or place equal weight on operation at all photon energies of interest. In addition, some users may be best served by a double- or triple-period revolver device. In this paper, we present a method of narrowing the choice of undulator periods based on multi-objective techniques. Applications are shown in the context of the Advanced Photon Source Upgrade.

TUPPP052

Status of FLASH

FEL, electron, laser, undulator

1715

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

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

TUPPP073

Machine Parameter Studies for an FEL Facility Using STAFF

FEL, undulator, linac, emittance

1768

M.W. Reinsch, B. Austin, J.N. Corlett, L.R. Doolittle, P. Emma, G. Penn, D. Prosnitz, J. Qiang, A. Sessler, M. Venturini
LBNL, Berkeley, California, USA
J.S. Wurtele
UCB, Berkeley, California, USA

Designing an FEL facility requires balancing multiple science needs, FEL and accelerator physics constraints, and engineering limitations. STAFF (System Trade Analysis for an FEL Facility) is a MATLAB program that enables the user to rapidly explore a large range of Linac and FEL design options to meet science requirements. The code uses analytical models such as the Ming Xie formulas when appropriate and look-up tables when necessary to maintain speed and flexibility. STAFF's modular design simplifies the inclusion of new physics models for FEL harmonics, wake fields, cavity higher-order modes and aspects of linac design such as the optimization of a laser heater, harmonic linearizer, and one or more bunch compressors. Code for the microbunching instability has been included as well. STAFF also supports multiple undulator technologies. STAFF permits the user to study error tolerances and multiple beamlines so as to explore the full capabilities of an entire user facility. This makes it possible to optimize the integrated system in terms of performance metrics such as photons/pulse, photons/sec and tunability range.

TUPPP079

Design Alternatives for a Free Electron Laser Facility

FEL, linac, undulator, electron

1777

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

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

TUPPR002

Simulations of Positron Polarization in the Undulator-Based Source

undulator, positron, polarization, electron

1810

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

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

TUPPR040

Update on ILC Positron Source Study at ANL

positron, undulator, polarization, electron

1906

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

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

TUPPR042

On the Polarization Upgrade of ILC Undulator-based Positron Source

polarization, positron, undulator, electron

1912

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

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

TUPPR062

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

vacuum, wiggler, electron, damping

1960

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

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

TUPPR063

Investigation into Electron Cloud Effects in the ILC Damping Ring Design

vacuum, wiggler, electron, lattice

1963

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

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

TUPPR064

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

vacuum, electron, simulation, pick-up

1966

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

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

WEOBB02

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

laser, electron, cavity, linac

2146

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

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

Slides WEOBB02 [4.393 MB]

WEPPC033

RF and Surface Properties of Bulk Niobium and Niobium Film Samples

niobium, electron, quadrupole, collider

2278

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

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

WEPPC041

Tests of SRF Deflecting Cavities at 2K

cavity, SRF, vacuum, cryogenics

2300

J.D. Fuerst, D. Horan, J. Kaluzny, A. Nassiri, T.L. Smith, G. Wu
ANL, Argonne, USA

Funding: Work supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract No. DE-AC02-06CH11357.
The Advanced Photon Source (APS) at Argonne National Laboratory (ANL) is developing 2.8-GHz deflecting-mode superconducting rf cavities in collaboration with Jefferson Lab as part of a major facility upgrade. On-site testing of these cavities requires a new cryostat capable of operation at 2.0 K or less. The APS has leveraged facilities and expertise within ANL’s Physics Division to upgrade an existing test stand for continuous operation at temperatures as low as 1.7 K. A new cryogenic feedbox was fabricated and mated to an existing liquid helium “bucket” dewar with 0.6-m inside diameter and 1-m working depth. The configuration allows continuous sub-λ operation using warm vacuum pumping and helium make-up from the Physics Division’s existing cryoplant at heat loads up to 50 W dynamic, plus 15 W measured static load at 2.0 K. A 2.8-GHz TWT-based rf station has been installed and commissioned, providing up to 275 W of rf power. We describe the cryogenic and rf performance of the system and provide examples of cavity test results.

WEPPD019

Manufacturing and Welding Process of Straight Section of Aluminum Alloy UHV Chambers for Taiwan Photon Source

vacuum, synchrotron, radiation, synchrotron-radiation

2537

C.-C. Chang, C.K. Chan, C.L. Chen, J.-R. Chen, G.-Y. Hsiung, S-N. Hsu
NSRRC, Hsinchu, Taiwan

This paper describes the manufacturing process and welding sequence for the aluminum extrusion vacuum chamber for the straight sections in Taiwan Photon Source. The straight section composes of aluminum extrusion chamber of A6063 and BPM chamber of A6061 aluminum alloys. The straightness and flatness of these extrusion chambers are controlled under 0.1mm/m and 0.2mm/m, respectively. The BPM chambers are manufactured precisely in oil-free environment, which provide clean surface and a precise sealing surface after machining. All the components are assembled in pre-aligned support system through the welding process. The aluminum chamber for 24 straight sections has been welded. The results show the straightness of < 0.15mm/m, flatness of < 0.3mm/m, and leakage rates of < 2 × 10^-10 mbarl/sec. were achieved.

WEPPD021

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

vacuum, impedance, electron, synchrotron

2543

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

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

WEPPD022

Design of the Water-Cooling System for the Vacuum System of the TPS Storage Ring

vacuum, synchrotron, storage-ring, controls

2546

Y.C. Yang, C.K. Chan, J.-R. Chen, C.M. Cheng, G.-Y. Hsiung
NSRRC, Hsinchu, Taiwan

Taiwan Photon Source (TPS) was under construction since 2009. TPS vacuum system was designed in 10^-10 torr level and gas load from synchrotron light was almost confined in bending chambers. A water cooling system was designed to protect vacuum equipment including vacuum chambers and absorbers to avoid melting down by synchrotron light. There are 3 cooling loops for aluminum chambers and 4 loops for cooper absorbers in one unit cell. One prototype for unit cell, including arrangement of control terminal, monitor of flow rate and temperature, and vibration from cooling system will be tested.

WEPPD024

A Study of Vacuum Pressure in TPS Cells

vacuum, site, electron, controls

2552

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

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

WEPPD026

Design and Fabrication of NSLS-II Storage Ring Vacuum Chambers and Components

vacuum, storage-ring, multipole, impedance

2558

H.-C. Hseuh, A.T. Anderson, L. Doom, M.J. Ferreira, C. Hetzel, C. Longo, V. Ravindranath, K. Roy, S.K. Sharma, J.L. Tuozzolo, K. Wilson
BNL, Upton, Long Island, New York, USA

Funding: Work performed under the auspices of U.S. Department of Energy, under contract DE-AC02-98CH10886
The National Synchrotron Light Source II, a 3-GeV, 792-meter circumference, synchrotron radiation facility with ultra-high-flux and brightness, is under construction at Brookhaven National Laboratory. The storage ring vacuum chambers are mainly made of extruded aluminium but with a few made of stainless steel and inconel. The synchrotron radiation from bending magnets is intercepted at discrete photon absorbers made of GlidCop. NEG strips in the ante-chamber provide the distributed pumping, while lumped ion pumps and titanium sublimation pumps at photon absorbers remove the desorbed gas. The complex vacuum system is being assembled and integrated in-house. This paper describes the design and fabrication of both standard and special vacuum chambers, the low impedance RF shielded bellows and the photon absorbers. The vacuum system is now moving into the conditioning, installation and testing phase. Details and experience from the large scale production, testing and lesson learned will also be presented.

WEPPD032

Heat Load Studies in Target and Collimator Materials for the ILC Positron Source

positron, polarization, undulator, target

2576

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

An intense polarized positron beam for future linear colliders can be produced using a high power beam of circularly polarized photons which penetrates a thin titanium-alloy target. The degree of polarization can be increased by cutting the outer part of the photon beam generated in a helical undulator using a collimator in front of the target. However, the photon beam induces substantial heat load and stress inside the target and collimator materials. In order to avoid failure of these components the stress evolution has been simulated. The results as well as the corresponding material arrangements for the photon collimator design are presented.

WEPPD041

The Strategy between High Precision Temperature Control and Energy Saving for Air-Conditioning System

controls, monitoring, target, feedback

2603

Z.-D. Tsai, W.S. Chan, J.-C. Chang, C.S. Chen, Y.-C. Chung, C.W. Hsu, C.Y. Liu
NSRRC, Hsinchu, Taiwan

In the Taiwan Light Source (TLS), several studies related to the temperature stability for air conditioning system continued to be in progress. Using new control philosophy can minimize temperature variations effectively. A high precision temperature control within ±0.05°C for air condition system has been conducted to meet the more critical stability requirement. Due to the importance of energy saving issue, the power consumption of air conditioning system was also upgraded and intended to reduce extensively. The paper addresses some experience between high precision temperature control and energy saving about operation of air conditioning system. The significant improvements proven that both targets can achieve simultaneously.

WEPPD045

An Application of Multi-stage Adjustable Shock Absorbers for the Girders of Storage Ring in Taiwan Photon Source

damping, acceleration, controls, storage-ring

2615

C.-S. Lin, J.-R. Chen, M.L. Chen, H.C. Ho, K.H. Hsu, D.-G. Huang, C.K. Kuan, W.Y. Lai, C.J. Lin, H.M. Luo, S.Y. Perng, P.L. Sung, Y.L. Tsai, T.C. Tseng, H.S. Wang, M.H. Wu
NSRRC, Hsinchu, Taiwan
D.-Y. Chiang
NCKU, Tainan city, Taiwan

Beam stability is a major concern for the operation of the Taiwan Photon Source (TPS). One of the many factors to instability of electron beam is mechanical vibration of the accelerator components. The TPS uses steel girders to support the magnets and vacuum chambers in the storage ring. Three pedestal and six mover assemblies support the girders. Multi-stage adjustable shock absorbers are designed for passive vibration damping, and presently installed between the girders and the pedestals. Through adjusting the amount of hydraulic fluid which bypasses the damping passage between two hydraulic chambers, the desired damping coefficient of the damping absorbers can be achieved. Experimental results of modal testing presented in this paper show that the multi-stage adjustable damping absorbers under the assembly of the girders reduced the level of girder vibration.

WEPPD055

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

cavity, laser, electron, scattering

2645

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

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

WEPPD061

Quality Control of Modern Linear Accelerator: Dose Stability Long and Short-term

controls, radiation, factory, monitoring

2660

T.U. Uddin
NICRH, Dhaka, Bangladesh

Quality Control (QC) data of modern linear accelerators, collected by National Institute of Cancer Research and Hospital, Dhaka, Bangladesh between the years 2006 and 2010, were analyzed. The goal was to provide information for the evaluation and elaboration of QC of accelerator outputs and to propose a method for QC data analysis. Short- and long-term drifts in outputs were quantified by fitting empirical mathematical models to the QA measurements. Normally, long-term drifts were well (≤1.5%) modeled by either a straight line or a single-exponential function. A drift of 2% occurred in 18 ± 12 months. The shortest drift times of only 2–3 months were observed for some new accelerators just after the commissioning but they stabilized during the first 2–3 years. The short-term reproducibility and the long-term stability of local constancy checks, carried out with a sealed plane parallel ion chamber, were also estimated by fitting empirical models to the QC measurements. The reproducibility was 0.3–0.6% depending on the positioning practice of a device. Long-term instabilities of about 0.3%/month were observed for some checking devices.

WEPPP017

Recent Results at the SPARC_LAB Facility

laser, electron, plasma, injection

2758

M. Ferrario, D. Alesini, M.P. Anania, M. Bellaveglia, R. Boni, M. Castellano, E. Chiadroni, G. Di Pirro, A. Drago, A. Esposito, A. Gallo, C. Gatti, G. Gatti, A. Ghigo, T. Levato, E. Pace, L. Pellegrino, R. Pompili, A.R. Rossi, B. Spataro, P. Tomassini, C. Vaccarezza, F. Villa
INFN/LNF, Frascati (Roma), Italy
A. Bacci, C. De Martinis, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
G. Dattoli, E. Di Palma, L. Giannessi, A. Petralia, M. Quattromini, C. Ronsivalle, I.P. Spassovsky, V. Surrenti
ENEA C.R. Frascati, Frascati (Roma), Italy
D. Di Giovenale
INFN-Roma II, Roma, Italy
U. Dosselli
INFN, Roma, Italy
R. Faccini
INFN-Roma, Roma, Italy
R. Fedele
Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli, Italy
M. Gambaccini
INFN-Ferrara, Ferrara, Italy
D. Giulietti
UNIPI, Pisa, Italy
L.A. Gizzi, L. Labate
CNR/IPP, Pisa, Italy
P. Londrillo
INFN-Bologna, Bologna, Italy
S. Lupi
Università di Roma I La Sapienza, Roma, Italy
A. Mostacci, L. Palumbo
Rome University La Sapienza, Roma, Italy
G. Passaleva
INFN-FI, Sesto Fiorentino, Italy
V. Petrillo
Universita' degli Studi di Milano, Milano, Italy
J.V. Rau
ISM-CNR, Rome, Italy
G. Turchetti
Bologna University, Bologna, Italy

A new facility named SPARC_LAB (Sources for Plasma Accelerators and Radiation Compton with Lasers and Beams) has been recently launched at the INFN National Labs in Frascati, merging the potentialities of the old projects SPARC and PLASMONX. The SPARC project, a collaboration among INFN, ENEA and CNR, is now completed, hosting a 150 MeV high brightness electron beam injector which feeds a 12 meters long undulator. Observation of FEL radiation in the SASE, Seeded and HHG modes has been performed from 500 nm down to 40 nm wevelength. A second beam line has been also installed to drive a narrow band THz radiation source. In parallel to that, INFN decided to host a 300 TW laser that will be linked to the linac and devoted to explore laser-matter interaction, in particular with regard to laser-plasma acceleration in the self injection and external injection modes, (the PLASMONX experiments). The facility will be also used for particle driven plasma acceleration experiments (the COMB experiment). A Thomson scattering experiment coupling the electron bunch to the high-power laser to generate coherent monochromatic X-ray radiation is also in the commissioning phase.

WEPPP027

PBG-slab Embedded Traveling Wave Structure for Planar Beam Accelerator Application

electron, HOM, acceleration, lattice

2784

Y.-M. Shin
Fermilab, Batavia, USA

The oversized traveling wave (TE10-mode) channel integrated with the photonic-band-gap (PBG) slab arrays have been investigated for planar beam accelerator application. Simulation analysis showed that the slab arrays allow only the PBG-modes (5-6 GHz) to propagate with ~ 2 dB of insertion loss, corresponding to ~ 1.14 dB/cm attenuation, which thereby effectively suppresses trapped non-PBG modes down to ~ -14.3 dB/cm. It will enable monochromatic propagation of fundamental acceleration modes along the heavily over-moded planar waveguide without anomalous excitation of unstable trapped HOMs. The saturated maximum field gradients of the accelerating structure have been analyzed with respect to operational frequency bands corresponding to structural sizes. The field gradient of the guided PBG-mode has been investigated with finite-integral-method (FIM) simulations at W-band. This mode-filter could be utilized for HOM dampers in high aspect ratio (HAR) planar beam accelerators. An experimental test is currently under consideration.

WEPPP067

Commissioning Results of Slow Orbit Feedback using PID Controller Method for the Siam Photon Source

feedback, controls, storage-ring, LabView

2861

S. Klinkhieo, S. Boonsuya, P. Klysubun, S. Krainara, P. Songsiriritthigul, P. Sudmuang, N. Suradet
SLRI, Nakhon Ratchasima, Thailand
S. Rujirawat
Suranaree University of Technology, Nakhon Ratchasima, Thailand

A slow orbit feedback (SOFB) system has been developed to improve the orbit stability for the storage ring of the Siam Photon Source (SPS). The SOFB uses a PID controller method utilizing LabVIEW channel to access 20 BPMs and 28 correctors of the storage ring. The first phase implementation of the feedback loops based on this method was operated at 0.05Hz of sampling frequency, which reduce the fluctuation of both horizontal and vertical positions of the orbit from ~200 microns down to ~30 microns. The commissioning results indicate that further work and hardware upgrade are required. A higher sampling frequency at least 30Hz is strongly required for PID controller implementation. Upgrading of the existing 12-bit resolution corrector power supplies is also necessary. The basic principle of PID algorithms, hardware, software and commissioning results of the current SOBF system, as well as a future development plan, will be presented.

WEPPP069

Performance Enhancements for the Transverse Feedback System at the Advanced Photon Source

feedback, EPICS, storage-ring, controls

2867

N.P. Di Monte, R.I. Farnsworth, A.J. Scaminaci
ANL, Argonne, USA

With the success of the transverse feedback system at the Advanced Photon Source (APS), an upgrade to this system is being developed. The current system is operating at a third of the storage ring bunch capacity, or 324 of the available 1296 bunches. This upgrade will allow the sampling of all 1296 bunches and make corrections for all selected bunches in a single storage ring turn. To facilitate this upgrade, a new analog I/O board capable of 352-MHz operation is being developed along with a P0 bunch cleaning circuit. The clock cleaning circuit is also needed for the high speed analog output circuit, which is transmitted about 200 m to a separate DAC unit in real time. This remote DAC will have its transceiver data rate triple from 2.3 Gb to about 7 Gb on a fiber optic link. This paper will discuss some of the challenges in reducing the clock jitter from the system P0 bunch clock along with the necessary FPGA hardware upgrades and algorithm changes, all of which are required for the success of this upgrade.

WEPPP071

Phase Noise Studies at the Advanced Photon Source

simulation, storage-ring, synchrotron, feedback

2873

N. Sereno, G. Decker, R.M. Lill, B.X. Yang
ANL, Argonne, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
Phase noise generated primarily by power line harmonics modulating the 352-MHz rf system in the APS storage ring is a dominant source of high- frequency beam motion, both longitudinally and transversely, due to dispersion in the lattice. It also places fundamental limits on the ability to generate picosecond-scale x-ray pulses for fast pump / probe experiments*. Measurements using turn-by-turn beam position monitors (BPMs) located at high-dispersion locations are compared and contrasted with results from a dedicated S-band phase detector connected to either a capacitive pickup electrode or a diamond x-ray detector. Horizontal beam position at high-dispersion locations is related directly to beam phase by a very simple relation involving the momentum compaction. Simulation results are used to validate this relationship and to quantify the relation between phase noise on the main rf vs beam arrival time jitter.
* A. Zholents et al., NIM A 425, 385 (1999).

WEPPP088

Auto-alignment System and CalibrationPprocedure in TPS Girder System

alignment, laser, survey, storage-ring

2918

W.Y. Lai, J.-R. Chen, M.L. Chen, H.C. Ho, K.H. Hsu, D.-G. Huang, C.K. Kuan, C.-S. Lin, C.J. Lin, H.M. Luo, S.Y. Perng, P.L. Sung, Y.L. Tsai, T.C. Tseng, H.S. Wang, M.H. Wu
NSRRC, Hsinchu, Taiwan

The TPS (Taiwan photon source) project is under construction and will be finished in the December 2012. Considering the floor’s deformation with time and frequent earthquakes at Taiwan, the survey and alignment procedure should be taken quite often. For dealing with these difficulties and improving accuracy of girder’s position, a highly accurate auto-tuning girders system was designed to accomplish the alignment tasks. There are two cells of TPS girders and varied sensor modulus set up for testing the auto-tuning system. The adjustment of the system converges to less than 6um, and the repeatability of the testing is under 10 um. For improving the accuracy of girders position, that is critical thing to make sure all the calibration of sensors modulus correctly and accurately. The calibration procedure about sensor modular and testing results is described in this paper.

WEPPP095

Digital Pulse Processor for High Demanding Synchrotron Spectroscopy

EPICS, controls

2929

S. Bucik, A. Bardorfer, B.B. Baricevic, R. Hrovatin, E. Janezic, B. Repič, D. Škvarč
I-Tech, Solkan, Slovenia
M. Vencelj
JSI, Ljubljana, Slovenia

The availability of brighter synchrotorn X-ray sources enable more complex experiments, such as 2D or 3D X-mapping. All the electrical signals generated in scmiconductive detectors are then processed and analysed by fast digital pulse processors (DPP). The poster presents the state of the art DPP currently in development by Instrumentation Technologies . We will discuss the signal transformation and processing from the detector preamplifier output to the final result: energy histogram and time stamped list mode. The signal processing chain starts with signal conditioning of the analog input signal. After the ADCs transformation, all the signal processing in the digital domain is done in FPGA. To each measured pulse a time-stamp is applied. Libera BASE FDK enables customer specific algorithms to be included in the FPGA.

THYA02

Ultracompact Accelerator Technology for a Next-generation Gamma-Ray Source

gun, klystron, laser, electron

3190

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

Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
This presentation will report on the technology choices and progress manufacturing and testing the injector and accelerator of the 250 MeV ultra-compact Compton Scattering X-ray Source under development at LLNL for homeland security applications.

Slides THYA02 [12.896 MB]

THEPPB008

Inverse Compton Scattering Experiment in a Bunch Train Regime Using Nonlinear Optical Cavity

laser, electron, cavity, linac

3245

A.Y. Murokh, R.B. Agustsson, S. Boucher, P. Frigola, T. Hodgetts, A.G. Ovodenko, M. Ruelas, R. Tikhoplav
RadiaBeam, Santa Monica, USA
M. Babzien, M.G. Fedurin, T.V. Shaftan, V. Yakimenko
BNL, Upton, Long Island, New York, USA
I. Jovanovic
Penn State University, University Park, Pennsylvania, USA

Inverse Compton Scattering (ICS) is a promising approach towards achieving high intensity, directional beams of quasi-monochromatic gammas, which could offer unique capabilities in research, medical and security applications. Practicality implementation of ICS sources, however, depends on the ability to achieve high peak brightness (~0.1-1.0 ICS photons per interacting electron), while increasing electron-laser beam interaction rate to about 10,000 cps. We discuss the results of the initial experimental work at the Accelerator Test Facility (ATF) at BNL to demonstrate ICS interaction in a pulse-train regime, using a novel laser recirculation scheme termed Recirculation Injection by Nonlinear Gating (RING). Initial experimental results and outlook are presented.

THEPPB012

Pressure Acoustic Waves in Positron Production Targets for Future Lepton Colliders

target, positron, collider, linear-collider

3257

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

Funding: This work is supported by the German Federal Ministry of Education and Research, Joint Research Project R&D Accelerator "Spin Management", contract number 05H10GUE
Future high energy lepton colliders demand high luminosities to achieve its physics goals. For the electron-positron linear collider, the generation of positrons is a non-trivial problem: the positron production target has to a survive huge amount of energy deposited by the bombardment of intense beams of electrons or photons. This causes a rapid increase of the temperature in the target within a very short time period. The resulting thermal stress induces pressure waves and can substantially shorten the operating life-span of for the target material. In this work, we study linear and effects of induced stress through pressure acoustic waves using a hydrodynamic model. The survivability issue of the target is discussed.

THPPC021

A Microwave Paraphoton and Axion Detection Experiment with 300 dB Electromagnetic Shielding at 3 GHz

cavity, shielding, coupling, pick-up

3320

M. Betz, F. Caspers
CERN, Geneva, Switzerland

Funding: Work supported by the Wolfgang-Gentner-Programme of the Bundesministerium für Bildung und Forschung (BMBF).
For the microwave equivalent of "light shining through the wall" (LSW) experiments, a sensitive microwave detector and very high electromagnetic shielding is required. The screening attenuation between the axion-generating cavity and the nearby detection-cavity should be greater than 300 dB, in order to push beyond the presently existing exclusion limits. To achieve these goals in practice, a "box in a box" concept was utilized for shielding the detection-cavity, while a vector signal analyzer was used as a microwave receiver with a very narrow resolution bandwidth in the order of a few micro-Hz. This contribution will present the experimental layout and show the results to date.

THPPD063

Zero Voltage Switching of Two-switch Flyback-Forward Converter

synchrotron, synchrotron-radiation, radiation, power-supply

3656

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

The traditional pulse-width-modulated flyback converter power switch has serious electromagnetic interference (EMI) and lower conversion efficiencies problems due to the hard-switching operations. This paper produces a zero voltage switching of flyback-forward converter with an active-clamp circuit, the traditional pulse-width-modulated flyback converter with a active clamp circuit to achieve zero-voltage-switching (ZVS) at both main and auxiliary switches, the active-clamp circuit can reduce most of switching loss and voltage spikes across the switches and improve the overall efficiency of the converter. The theoretical analysis of soft switching flyback-forward converter with an active-clamp circuit is verified exactly by a prototype of 50W with 100V input voltage, 5V output voltage and 30kHz operated frequency.

THPPR002

The Undulator Control System for the European XFEL

undulator, controls, quadrupole, electron

3966

S. Karabekyan, A. Beckmann, J. Pflüger
European XFEL GmbH, Hamburg, Germany
N. Burandt, J. Kuhn
Beckhoff Automation GmbH, Verl, Germany
A. Schöps
DESY, Hamburg, Germany

The European XFEL project is a 4th generation light source. The first beam will be delivered in the beginning of 2015 and will produce spatially coherent ≤80fs short photon pulses with a peak brilliance of 10³²–10³⁴ photons/s/mm²/mrad²/0.1% BW in the energy range from 0.26 to 29 keV at electron beam energies of 10.5 GeV, 14 GeV, or 17.5 GeV . The Undulator systems are used to produce photon beams for SASE 1, SASE 2 and SASE 3. Each undulator system consists of an array of undulator cells installed in a row along the electron beam. A single undulator cell itself consists of a planar undulator, a phase shifter, magnetic field correction coils and a quadrupole mover. This paper describes the design of the entire undulator control system including local and global control. It presents a concept of integration of the undulator control into the accelerator control system as well as into the experiment control.

THPPR022

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

neutron, radiation, simulation, synchrotron

4008

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

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

THPPR042

Optimisation of an Inverse Compton Scattering Experiment with a Real Time Detection Scheme Based on a Radio Luminescent Screen and Comparison of the X-rays Beam Characteristics with Simulations

electron, laser, emittance, scattering

4068

A.S. Chauchat, JP. Brasile
TCS, Colombes, France
A. Binet, V. Le Flanchec, J-P. Nègre
CEA/DAM/DIF, Arpajon, France
J.-M. Ortega
LCP/CLIO, Orsay, Cedex, France

To optimize the detection of an 11-keV X-Ray beam produced by Inverse Compton Scattering at the ELSA facility*, with a 17 MeV electron beam and a 532 nm laser, we demonstrate the use of a very sensitive detection scheme, based on a radio luminescent screen used in the spontaneous emission regime. It has proven to be very sensitive and very effective to detect 11-keV X-Rays while rejecting the overall ambient noise produced in a harder spectral range. It allowed us to optimize the electron-photon interaction probability by observing in real time the effect of both beams transport parameters. We could then compare simulation results with experimental measurements that appear to be in good agreement.
*A.S. Chauchat et al. Instrumentation developments for production and characterization of Inverse Compton Scattering X-rays and first results with a 17 MeV electron beam, NIMA, V.622, I.1, P.129-135

THPPR065

High Flux Laser-Compton Scattered Gamma-ray Source by Compressed Nd:YAG Laser Pulse.

laser, electron, microtron, resonance

4124

I. Daito, R. Hajima, T. Hayakawa, Y. Hayashi, M. Kando, H. Kotaki, T. Shizuma
JAEA, Kyoto, Japan
H. Ohgaki
Kyoto University, Institute for Advanced Energy, Kyoto, Japan

A non-destructive detection system of nuclear materials hidden in cargo containers is under development in Japan Atomic Energy Agency and Kyoto University. The system is able to be used for the identification of isotopes of special nuclear material in a container by employing Nuclear Resonance Fluorescence triggered by mono-energetic Laser Compton Scattered (LCS) gamma-ray tuned at the energy of the nuclear resonance. One of the most important technologies for such system is generation of gamma-rays at a flux of 3 x10⁵ photon/s. In order to achieve this gamma-ray flux with a compact system, a pulse compression system for Nd:YAG laser based on Stimulated Brillouin Scattering (SBS) has been developed. The laser pulse with a duration of 10 ns (FWHM) from a commercially available Nd:YAG laser is compressed down to a few hundreds ps. As a feasibility study of the proposed system, 400 keV gamma-ray generation is performed at Kansai Photon Science Institute by using 150 MeV electron beam from microtron accelerator and compressed Nd:YAG laser. Experimental results of laser pulse compression and gamma-ray generation are presented.

THPPR068

Laser Compton Scattering X-rays as a Tool for K-edge Densitometry

laser, electron, scattering, radiation

4133

M. Titberidze, K. Chouffani
IAC, Pocatello, IDAHO, USA

There is a huge interest in bright and tunable X-ray sources. These sources can be used in various research fields, including medical, biological and industrial fields. Laser Compton Scattering (LCS) technique gives us possibility to generate tunable, quasi monochromatic and polarized X-ray beam. One of the applications of LCS is the detection and quantitative identification of special nuclear materials (SNM) using K-edge densitometry(KED)method. Our group was the first one who has used a quasi-monochromatic LCS source to carry out KED experiments. The experiments showed that LCS technique could be used for SNM detection and quantification.

THPPR070

Development of Multi-collision Laser Compton Scattering X-ray Source on the Basis of Compact S-band Electron Linac

laser, electron, cavity, linac

4139

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

A compact hard X-ray source via laser Compton scattering is required for biological, medical and industrial science because it has many benefits about generated X-rays such as short pulse, quasi-monochromatic, energy tunability and good directivity. Our X-ray source is conventionally the single collision system between an electron pulse and a laser pulse. To increase X-ray yields, we have developed a multi-collision system with a multi-bunch electron beam and a laser optical cavity. The multi-bunch electron beam has already been generated from a Cs-Te photocathode rf gun system using a multi-pulse UV laser. The laser optical cavity have developed like a regenerative amplification including the collision point between the electron pulse and the laser pulse which is based on the Ti:Sa laser with a mode-locked frequency of 79.33 MHz. In this preliminary experiment, the modulated seed laser pulses were generated and leaded to the cavity, so that laser build-up amplification was performed in the cavity length of 3.78 m with two seed pulses. In this conference, we will describe the results of preliminary experiments for the multi-collision system and future plans.