IPAC2016 - List of Keywords (photon)

Paper	Title	Other Keywords	Page
MOPMB010	Compton Polarimetry at ELSA - Beamline and Detector Optimization	polarization, laser, electron, detector	95
	R. Koop, W. Hillert, M.T. Switka ELSA, Bonn, Germany
	Funding: Work supported by DFG within CRC TRR16 The Electron Stretcher Facility ELSA provides a polarized electron beam with energies of 0.5 - 3.2 GeV for double polarization hadron physics experiments. Monitoring the vertical electron polarization by Compton polarimetry in the stretcher ring has several advantages over the established polarization measurement by Moeller polarimetry. The Compton polarimeter setup presented consists of a 40 W cw disk laser featuring two polarized photon beams colliding head-on with the stored electron beam in ELSA. A silicon strip detector measures the vertical intensity profile of the backscattered photons. The reversal of handedness of the laser beam's circular polarization results in a polarization dependent vertical shift of this profile. From a calibration using time dependent polarization build-up due to the Sokolov-Ternov effect, the polarization degree of the electron beam can be extracted. After recent laser repairs as well as beamline and detector modifications, first measurement attempts of the electron's polarization degree were conducted. The performance of the beamline and first measurements are presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB010
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MOPMB028	Development of Beam Diagnostic System for the SPring-8 Upgrade	diagnostics, radiation, beam-diagnostic, emittance	149
	H. Maesaka, T. Ohshima, Y. Otake RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan H. Dewa, T. Fujita, K. Kobayashi, M. Masaki, S. Matsubara, T. Nakamura, S. Sasaki, S. Takano JASRI/SPring-8, Hyogo-ken, Japan
	The goal of the beam diagnostic system for the SPring-8 upgrade is to deliver brilliant X-rays enabled by the new low-emittance ring to experimental stations with ultimate stability. Developments of accurate electron and photon beam position monitors (EBPM and XBPM, respectively) with both short and long-term stability are the most critical. The EBPM sensitivity is also crucial for low-current beam commissioning to accomplish the first beam storage in the ring. We designed a button electrode to obtain sufficiently high-intensity signals while suppressing high-Q trapped modes leading to impedance and heating issues. We also designed a precise EBPM block and a rigid support to achieve mechanical accuracy and stability. Another challenge is the development of a reliable and stable XBPM, which should be an accurate reference for an orbit feedback without any photon-energy dependences. A significant improvement of a blade-type XBPM or an invention of a novel XBPM detecting the core of an intense X-ray beam are necessary. The other diagnostic instrumentations can be utilized for the new ring with minor improvements.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB028
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MOPMB029	Development Status of Linear Focal Cherenkov Ring Camera	electron, vacuum, laser, experiment	152
	K. Nanbu, T. Abe, H. Hama, F. Hinode, S. Kashiwagi, T. Muto, I. Nagasawa, H. Saito, K. Takahashi, C. Tokoku Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	Linear focal Cherenkov ring camera (LFC-Camera) has been developed for single shot measurement of longitudinal phase space distribution of quasi-relativistic electron beam, where the electron's velocity still depends on its energy. The LFC-camera employs velocity dependence of opening angle of Cherenkov light produced by electron beam to observe its energy (momentum) distribution. Since the Cherenkov light contains the time information if the radiator medium is thin enough, we can get the longitudinal phase space distribution measuring both time and energy spectra simultaneously using a streak camera. We employ a thin silica aerogel with water-free hydrophobic treatment as Cherenkov radiator. We have evaluated characteristics of the silica aerogel radiator, and demonstration of the LFC-camera at a beam diagnosis section of t-ATCS is being proceeded.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB029
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MOPMR033	Characterization of Beam Properties Using Synchrotron Light at Taiwan Photon Source	synchrotron, booster, storage-ring, injection	316
	C.Y. Liao, Y.-S. Cheng, K.T. Hsu, K.H. Hu, C.-C. Kuo, H.-J. Tsai, C.Y. Wu NSRRC, Hsinchu, Taiwan
	Taiwan Photon Source (TPS) is a third-generation 3-GeV synchrotron light facility, located in National Synchrotron Radiation Research Center (NSRRC) at Hsinchu Science Park. After overcoming many challenges, the storage beam current attained 520 mA in 2015 December. The synchrotron light monitors, including X-ray and visible light, are important diagnostic tools to characterize the various machine conditions. The booster beam dynamics during ramping and the beam properties of the storage ring were studied with synchrotron light. The results of measurements are presented in this report.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR033
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MOPOR016	Impedance Study with Single Bunch Beam at Taiwan Photon Source	impedance, storage-ring, synchrotron, vacuum	630
	C.-C. Kuo, P.J. Chou, K.T. Hsu, K.H. Hu, C.C. Liang, C.Y. Liao, Z.K. Liu, H.-J. Tsai, F.H. Tseng NSRRC, Hsinchu, Taiwan
	The impedance at Taiwan Photon Source was investigated. The effects of bunch current such as a tune change, a synchronous phase shift and a bunch lengthening under operation conditions at various stages were measured; the machine impedances were deduced. This report presents the results with insertion devices in various configurations.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR016
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MOPOW010	The Superconducting Soft X-ray Free-Electron Laser User Facility FLASH	FEL, operation, laser, electron	729
	M. Vogt, J. Feldhaus, K. Honkavaara, J. Rönsch-Schulenburg, S. Schreiber, R. Treusch DESY, Hamburg, Germany
	FLASH, the superconducting free-electron laser at DESY delivers up to several thousand photon pulses per second with wavelengths ranging from 52 nm down to as low as 4.2 nm and with pulse energies of up to 500 uJ to photon users at the FLASH1 beamline. In 2014 and 2015 a second beamline, FLASH2, has been commissioned in parallel to user operation at FLASH1. FLASH produces bunch trains of up to 800 bunches in 0.8 ms with a train repetition rate of 10 Hz. Each train can be split in sub-trains for FLASH1 and FLASH2, such that both beamlines receive bursts of bunches with full 10 Hz. Operational highlights are the latest SASE energy record of 600 uJ at 15 nm in FLASH2, and the first simultaneous SASE lasing of three undulator systems: FLASH1 (13.7 nm), sFLASH (38 nm), and FLASH2 (20 nm). sFLASH is the seeding experiment in the FLASH1 beamline. Moreover we will report on recent technical and operational improvements. A major success is the improved reliability and stability of the whole facility with shorter SASE tuning times.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW010
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MOPOW012	Transverse Coherence and Fundamental Limitation on the Pointing Stability of X-ray FELs	FEL, radiation, electron, emittance	735
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	The radiation from SASE FEL has always limited value of the degree of transverse coherence. When transverse size of the electron beam significantly exceeds diffraction limit, the mode competition effect does not provide the selection of the ground mode, and spatial coherence degrades due to contribution of the higher azimuthal modes. An important consequence of this effect are fluctuations of the spot size and pointing stability of the photon beam. These fluctuations are fundamental and originate from the shot noise in the electron beam. The effect of pointing instability becomes more pronouncing for shorter wavelengths. We analyze in detail the case of optimized SASE FEL and derive universal dependencies applicable to all operating and planned x-ray FELs. We show that the hard x-ray FELs driven by low energy beams may exhibit poor spatial coherence and bad pointing stability. * E.L. Saldin, E.A. Schneidmiller and M.V. Yurkov, Opt. Commun. 281(2008)1179. ** E.A. Schneidmiller and M.V. Yurkov, Proc. FEL2015 Conference, Daejeon, Korea, 2015, TUP021.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW012
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MOPOW013	Application of Statistical Methods for Measurements of the Coherence Properties of the Radiation from SASE FEL	radiation, FEL, undulator, electron	738
	E. Schneidmiller, M.V. Yurkov DESY, Hamburg, Germany
	Radiation of the SASE FEL operating in the linear regime possesses the properties of completely chaotic polarized light which happens due to start up of the amplification properties from the shot noise in the electron beam. One of the features of this statistical object is that probability distribution of the radiation pulse energy follows gamma distribution. Parameter of this distribution is the number of modes in the radiation pulse which is equal to inverse deviation of the energy fluctuations. Statistical analysis of the radiation energies measured within different spatial apertures allows us to determine the number of longitudinal and transverse modes. In addition, knowledge of the saturation length allows to determine the duration of the lasing part of the electron bunch, photon pulse duration, and coherence time. Knowledge of the number of transverse modes allows one to determine the degree of transverse coherence. In this report we present theoretical background of the proposed method and experimental results obtained at free electron laser FLASH. E.L. Saldin, E.A. Schneidmiller and M.V. Yurkov, Opt. Commun. 148 (1998) 383. ** C. Behrens et al., Phys. Rev. ST Accel. Beams 15 (2012) 030707.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW013
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MOPOW014	Measurements of Ultrasmall Charges with MCP Detector in FLASH Accelerator	detector, electron, undulator, laser	741
	O.I. Brovko, A.Yu. Grebentsov, A.V. Shabunov, E. Syresin JINR, Dubna, Moscow Region, Russia S. Schreiber, M.V. Yurkov DESY, Hamburg, Germany
	Structure of the dark current passed through the undulator is a matter of great concern. Two effects can contribute to the dark current: emission of electrons from "hot" spots in the gun, and generation of "ghost" bunches due to possible leakage of the photoinjector laser. MCP based photon detector has been used for measurements of radiation energy from electron bunch. For small radiation densities the light is detected by direct illumination of the MCP plate, and for large densities a small angle scattering scheme is realized when metallic mesh scatters tiny fraction of light on the MCP plate. In the present experiment we used geometry of direct illumination of MCP plate aiming detection of "ghost" bunches which may generate parasitically from the laser driven electron gun. Reduction of background conditions allowed us to detect light produced by electron bunches with extremely small charges, down to a few femtocoulmb. We measured for the first time structure of the dark current passing through the FLASH undulator. We have also been able to measure a high contrast of radiation produced by the photoinjector laser pulses switched on and off by a 1 MHz repetition rate Pockels cells.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW014
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MOPOW017	Generation of GeV Photons from X-ray Free Electron Laser Oscillators	electron, laser, FEL, scattering	751
	R. Hajima JAEA, Ibaraki-ken, Japan M. Fujiwara RCNP, Osaka, Japan
	We propose generation of narrow-bandwidth GeV photons, gamma-rays, via Compton scattering of hard X-ray photons in X-ray free-electron laser oscillators. The gamma-rays have a narrow-bandwidth spectrum with a sharp peak, ~0.1% (FWHM), due to the nature of Compton scattering in relativistic regime. Such gamma-rays will be a unique probe for studying hadron physics. We discuss features of the gamma-ray source, flux, spectrum, polarization, tunability and energy resolution.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW017
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MOPOW029	The Soft X-ray Self-seeding System Design for SXFEL User Facility	undulator, FEL, electron, simulation	785
	K.Q. Zhang, T. Liu, D. Wang SINAP, Shanghai, People's Republic of China Y. Feng SLAC, Menlo Park, California, USA
	X-ray free electron laser driven by SASE probes the evolution of the new generation light source in high brightness, transverse coherence. However, since SASE achieves lasing from random shotnoise, Poor longitudinal coherence and relative wide bandwidth of SASE FEL limit the operation of many type experiments. Self-seeding as a promising scheme produces longitudinal coherence and even narrower bandwidth radiation by a monochromatic seeding instead of external seeding. The self-seeding system design based on the grating monochromator is carried out for SXFEL user facility across the photon energy from 800-1200 eV. The grating monochromator with a resolution power of 〖10〗^-4 can provide a monochromatic seeding pulse to the seeding undulator. The layout design and simulations of the scheme are presented. It is showing that the self-seeding system for SXFEL user facility is able to improve SASE FEL longitudinal coherence significantly.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW029
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MOPOW039	An Oscillator Configuration for Full Realization of Hard X-ray Free Electron Laser	electron, laser, optics, free-electron-laser	801
	K.-J. Kim, T. Kolodziej, R.R. Lindberg, D. Shu, Yu. Shvyd'ko, S. Stoupin ANL, Argonne, Ilinois, USA V.D. Blank, S. Terentiev TISNCM, Troitsk, Russia Y. Ding, W.M. Fawley, J.B. Hastings, Z. Huang, J. Krzywinski, G. Marcus, T.J. Maxwell SLAC, Menlo Park, California, USA N.A. Medvedev CFEL, Hamburg, Germany W. Qin PKU, Beijing, People's Republic of China J. Zemella DESY, Hamburg, Germany
	Funding: Work at ANL supported under US Department of Energy contract DE-AC02-76SF00515 and at SLAC by the U.S. Department of Energy, Office of Science, under Contract No. DE-ACO2-O6CH11357 An X-ray free electron laser can be built in an oscillator (XFELO) configuration by employing an X-ray cavity with Bragg mirrors such as diamond. An XFELO at the 5th harmonic frequency may be implemented at the LCLS II using its 4 GeV superconducting linac. The XFELO will provide stable, coherent, high-spectral-purity hard x-rays. In addition, portions of its output may be enhanced by the LCLS amplifier for stable pulses of ultrashort duration determined by the electron bunch length. Much progress has been made recently on the feasibility of an XFELO: Analytical and numerical methods have been developed to compute the performance of a harmonic XFELO. The energy spread requirement over a sufficient length of the bunch can be met by temporal shaping of the photo-cathode drive laser. Experiments at the APS have shown that Be-compound refractive lenses are suitable for a low-loss focusing and that the synthetic diamond crystals can withstand the intense x-ray exposure, in accord with estimates based on molecular dynamics considerations. A strain-free mounting of thin diamond crystal (< 100 microns) can be realized by shaping a thick diamond into a blind alley*. R. R. Lindberg et al., PRSTAB 1010701 (2011) W. Qin et al., this conference * N. Medvedev et al., Phys. Rev. B 88, 224304 (2013) **** S. Terentyev, private communication
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW039
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MOPOW040	High Efficiency, High Brightness X-ray Free Electron Lasers via Fresh Bunch Self-Seeding	electron, undulator, simulation, extraction	805
	C. Emma, C. Pellegrini UCLA, Los Angeles, USA M.W. Guetg, A.A. Lutman, A. Marinelli, C. Pellegrini, J. Wu SLAC, Menlo Park, California, USA
	High efficiency, terawatt peak power X-ray Free Electron Lasers are a promising tool for enabling single molecule imaging and nonlinear science using X-rays. Increasing the efficiency of XFELs while achieving good longitudinal coherence can be achieved via self-seeding and undulator tapering. The efficiency of self-seeded XFELs is limited by two factors: the ratio of seed power to beam energy spread and the ratio of seed power to shot noise power. We present a method to overcome these limitations by producing a strong X-ray seed and amplifying it with a small energy spread beam. This is achieved by selectively suppressing lasing for part of the bunch in the SASE section. In this manner we can saturate with the seeding electrons and amplify the strong seed with 'fresh' electrons downstream of the monochromator. Simulations of this scenario are presented for two systems, an optimal superconducting undulator design and the LCLS. In the case of the LCLS we examine how betatron oscillations leading to selective suppression are induced by using the transverse wakefield of a parallel plate dechirper. We also discuss extending the selective suppression scheme to chirped electron bunches.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW040
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MOPOW044	Commissioning of the RadiaBeam / SLAC Dechirper	electron, wakefield, controls, alignment	809
	M.W. Guetg, K.L.F. Bane, A. Brachmann, A.S. Fisher, Z. Huang, R.H. Iverson, P. Krejcik, A.A. Lutman, T.J. Maxwell, A. Novokhatski, G. Stupakov, J. Zemella, Z. Zhang SLAC, Menlo Park, California, USA M.A. Harrison, M. Ruelas RadiaBeam Systems, Santa Monica, California, USA J. Zemella DESY, Hamburg, Germany Z. Zhang TUB, Beijing, People's Republic of China
	We present results on the commissioning of the two-module RadiaBeam / SLAC dechirper system at LCLS. This is the first installation and measurement of a corrugated dechirper at high energy (4.4 - 13.3 GeV), short pulses (< 200 fs) and while observing its effect on an operational FEL. Both the transverse and longitudinal wakefields allow more flexible electron beam tailoring. We verify that, for a single module at a given gap, the strength of the longitudinal wake on axis and the dipole near the axis agree well with the theoretical values. Using direct longitudinal phase space mapping and X-ray FEL spectrum measurements we demonstrate the energy chirp control capabilities.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW044
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MOPOW045	Measurement of Advanced Dispersion-based Beam-tilt Correction	lattice, electron, FEL, laser	813
	M.W. Guetg, F.-J. Decker, Y. Ding, P. Emma, Z. Huang, T.J. Maxwell SLAC, Menlo Park, California, USA
	Funding: DOE contract \#DE-AC02-76SF00515 Free electron lasers in the X-ray regime require a good slice alignment along the electron bunch to achieve their best performance. A transverse beam slice shift reduces this alignment and spoils projected emittance and optics matching. Coherent synchrotron radiation, specifically for over-compression going through full compression, and transverse wakefields are major contributors to this. In the case of the large-bandwidth operation, with a strong energy chirp on the bunch, this misalignments furthermore reduce the spectral bandwidth of the FEL pulse. Well-defined manipulation of dispersion allows to compensate for this slice centroid shifts, therefore enhancing lasing power and in case of the large bandwidth mode, spectral bandwidth. This work shows the first application of this correction on an X-ray FEL resulting in increase in beam-power and bandwidth.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW045
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TUZA02	Twin-bunch Two-colour FEL at LCLS	electron, laser, free-electron-laser, undulator	1032
	A. Marinelli, R.N. Coffee, F.-J. Decker, Y. Ding, R.C. Field, S. Gilevich, Z. Huang, D. Kharakh, H. Loos, A.A. Lutman, T.J. Maxwell, J.L. Turner, S. Vetter SLAC, Menlo Park, California, USA
	Twin electron bunches have been the subject of much investigation at the Linac Coherent Light Source, due to their many applications to X-ray free-electron lasers (X-FEL). Twin bunches are trains of two electron bunches that are accelerated and compressed within the same accelerating RF period. At LCLS, these bunches are used in the downstream FEL undulator to generate two X-ray pulses of different energies for pump/probe applications or de novo phase determination of protein crystals. The spectral and temporal shaping of the two bunches requires exquisite control of the compression system to vary the main parameters of the system in a controlled way (peak current, temporal delay and energy separation). I will discuss recent experimental and theoretical results on this subject. In particular I will focus on the demonstration of mJ-level two-color X-ray pulses using twin bunches, as well as the temporal and spectral control of this new mode of operation. Finally, I will discuss our experience with user experiments as well as our future directions of investigation.
	Slides TUZA02 [5.738 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUZA02
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TUOCB01	First Commissioning of the SuperKEKB Vacuum System	vacuum, electron, status, positron	1086
	Y. Suetsugu, H. Hisamatsu, T. Ishibashi, K. Kanazawa, K. Shibata, M. Shirai, S. Terui KEK, Ibaraki, Japan
	The SuperKEKB, an electron-positron collider with asymmetric energies in KEK, has started the first commissioning with beams this year. One of major tasks in the commissioning is the beam scrubbing of new beam pipes in order to increase the beam lifetime and to decrease the background noise of the particle detector in the coming physics run. The temperatures and the vacuum pressures of new vacuum components, such as the bellows chambers, gate valves and the beam collimators, should be checked in this run. The decrease rate in the vacuum pressure are measured to estimate the vacuum scrubbing effect. Reported here will be the results obtained during the first commissioning and the present status of the vacuum system.
	Slides TUOCB01 [2.526 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUOCB01
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TUOCB02	Low Secondary Electron Yield of Laser Treated Surfaces of Copper, Aluminium and Stainless Steel	electron, laser, cavity, framework	1089
	R. Valizadeh, P. Goudket, O.B. Malyshev, B.S. Sian, S. Wang STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom M.D. Cropper, S. Wang Loughborough University, Loughborough, Leicestershire, United Kingdom P. Goudket Cockcroft Institute, Warrington, Cheshire, United Kingdom B.S. Sian UMAN, Manchester, United Kingdom N. Sykes Micronanics Laser Solution Center, Didcot, United Kingdom
	Funding: STFC Reduction of SEY was achieved by surface engineering through laser ablation with a laser operating at • = 355 nm. It was shown that the SEY can be reduced to near or below 1 on copper, aluminium and 316LN stainless steel. The laser treated surfaces show an increased surface resistance, with a wide variation in resistance found de-pending on the exact treatment details. However, a treated copper surface with similar surface resistance to aluminium was produced.
	Slides TUOCB02 [94.339 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUOCB02
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TUPMB050	Development of Multi-channel Line for the NSRRC Cryogenic System	cryogenics, vacuum, radiation, synchrotron	1212
	P.S.D. Chuang, S.-H. Chang, W.-S. Chiou, F. Z. Hsiao, H.C. Li, W.R. Liao, T.F. Lin, H.H. Tsai NSRRC, Hsinchu, Taiwan
	For the past few years, the technology of X-ray photon source is getting more and more advanced, more and more countries are now striving to build the biggest synchrotron facility to meet its' need. In Taiwan, the construction of an electron accelerator with the energy of up to 3.5 GeV is constructed to fulfill the strong demands for an X-ray photon source with high brilliance and flux. Thus, to let the TPS be under stable operation, the cryogenic system is therefore very important. The refrigerant of the TPS Cryogenic System is Liquid Helium, to maintain liquid helium in its state, the temperature has to be maintained under 4.5K, however to let liquid helium turn into gas helium, only 20 W is needed. Therefore, the Multi-Channel Line is developed in our system to prevent heat from conduction in and letting liquid helium vaporize. Several mechanical parts have been designed to reduce heat loss and meet its needs, for example the Spacer. The paper presents a design methodology of long multi-channel helium cryogenic transfer lines. It describes some aspects thermo-mechanical calculation, supporting structure and contraction protection.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB050
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TUPOW041	Optimization Studies for the Beam Dynamic in the RF Linac of the ELI-NP Gamma Beam System	electron, laser, linac, emittance	1850
	C. Vaccarezza, D. Alesini, M. Bellaveglia, M.E. Biagini, G. Di Pirro, A. Gallo, A. Ghigo, S. Guiducci, A. Vannozzi, A. Variola INFN/LNF, Frascati (Roma), Italy A. Bacci, I. Drebot, D.T. Palmer, A.R. Rossi, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy G. Campogiani Rome University La Sapienza, Roma, Italy A. Giribono, A. Mostacci, L. Palumbo University of Rome La Sapienza, Rome, Italy V. Petrillo Universita' degli Studi di Milano & INFN, Milano, Italy L. Sabbatini Consorzio Laboratorio Nicola Cabibbo, Frascati, Italy
	The ELI-NP GBS is an high spectral density and monochromatic gamma ray source based upon the inverse Compton scattering effect now under construction in Magurele. Its relevant specifications are brilliance higher than 10²¹, 0.5% monochromaticity and a 0.2-19.5 MeV energy tunability. Strong requirements are set for the electron beam dynamic: the control of both the transverse normalized emittance and the energy spread to optimize the spectral density and guarantee the mono chromaticity of the emitted radiation. On this basis the RF Linac optimization has been performed for the designed energy range; a sensitivity analysis of the machine to possible jitters, errors and so on has been also performed, the simulations results hare here presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW041
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TUPOW042	Expected Gamma Spectra at ELI-NP-GBS	laser, polarization, electron, collimation	1854
	I. Drebot, C. Curatolo Universita' degli Studi di Milano e INFN, Milano, Italy A. Bacci, A.R. Rossi, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy A. Giribono University of Rome "La Sapienza", Rome, Italy V. Petrillo Universita' degli Studi di Milano & INFN, Milano, Italy C. Vaccarezza, A. Variola INFN/LNF, Frascati (Roma), Italy
	The ELI-NP-GBS is an advanced source of up to 20 MeV Gamma Rays based on Compton back-scattering. We present the investigation of the production of the ELI-NP gamma photon beam generated by Compton back-scattering between the electron bunch accelerated in the linac and the laser pulse. At the interaction point (IP), the Compton backscattering properties, as spectral flux, brilliance and polarization are evaluated by the Klein-Nishina cross section. The gamma beam produced has energy ranging from 0.2 to 19.5 MeV and bandwidth of 0.5%. In order to define the optimal layout and evaluate the performances of the collimation and detection systems, a detailed Monte Carlo simulation activity has been carried out taking into account possible jitters and errors.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW042
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TUPOW043	Electron Beam Dynamics Studies for ELI-NP GBS Linac	electron, linac, operation, beam-loading	1857
	A. Giribono, F. Cardelli, L. Palumbo, L. Piersanti University of Rome La Sapienza, Rome, Italy D. Alesini, A. Gallo, C. Vaccarezza, A. Vannozzi INFN/LNF, Frascati (Roma), Italy A. Bacci, C. Curatolo, I. Drebot, V. Petrillo, A.R. Rossi, L. Serafini Istituto Nazionale di Fisica Nucleare, Milano, Italy G. Campogiani Rome University La Sapienza, Roma, Italy F. Cardelli, L. Piersanti INFN-Roma1, Rome, Italy L. Palumbo INFN-Roma, Roma, Italy
	The ELI-NP Gamma Beam System is an advanced gamma ray source based on the Compton back-scattering effect with unprecedented specifications of brilliance ( >10²¹), monochromaticity (0.5%) and energy tunability (0.2 - 19.5 MeV), presently under construction in Magurele-Bucharest (RO). Here the head-on collision is foreseen between an intense high power laser beam and a high brightness high quality electron beam with a maximum kinetic energy of 740 MeV. The electron beam dynamics analysis and control for the ELI-NP GBS Linac in the single and multi bunch mode have been investigated and are here illustrated.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW043
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TUPOW046	Development and Upgrade Plan of an X-ray Source Based on Laser Compton Scattering in Laser Undulator Compact X-ray Source(LUCX)	laser, electron, detector, cavity	1867
	M.K. Fukuda, S. Araki, Y. Honda, N. Terunuma, J. Urakawa KEK, Ibaraki, Japan M. Kageyama, M. Kuribayashi Rigaku Corporation, XG & Core Technology, Tokyo, Japan A. Momose, M.P. Olbinado, Y. Wu Tohoku University, Institute of Multidisciplinary Research for Advanced Materials, Sendai, Japan K. Sakaue Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan M. Washio RISE, Tokyo, Japan
	Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan. We have been developing a compact X-ray source based on Laser Compton scattering(LCS) at Laser Undulator Compact X-ray source(LUCX) accelerator in KEK. Our aim is to obtain a clear X-ray image in a shorter period of times and the target number of X-ray is 1.7x10⁷ photons/pulse with 10% bandwidth. In the accelerator, an electron beam with the energy of 18-24 MeV is generated by an S-band normal conducting accelerator. The beam is collided with a laser pulse stacked in a 4-mirror planar optical cavity and then 6-10 keV X-rays are generated by LCS. Presently, the generation of X-rays with the number of 3x10⁶ photons/pulse at the collision point has been achieved. X-ray imaging test such as refraction contrast images and phase contrast imaging with Talbot interferometer has also started. To increase the intensity of X-rays, we are continuing the tuning of the electron beam and the optical cavity because the exposure time of X-ray imaging is too long now. We are also planning to increase the beam energy by appending the accelerating tube. In this conference, the recent results and upgrade plan in LUCX will be reported.
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TUPOW049	Expected Results From Channeling Radiation Experiments at Fast	detector, electron, background, emittance	1873
	T. Sen, D.R. Broemmelsiek, D.R. Edstrom Fermilab, Batavia, Illinois, USA J. Hyun Sokendai, Ibaraki, Japan D. Mihalcea, P. Piot Northern Illinois University, DeKalb, Illinois, USA W.D. Rush KU, Lawrence, Kansas, USA
	Funding: Fermilab is operated by Fermi Research Alliance LLC under DOE contract No. DE-AC02CH11359 The photoinjector at the new Fermilab FAST facility will accelerate electron beams to about 50 GeV. After initial beam commissioning, channeling radiation experiments to generate hard X-rays will be performed. In the initial stage, low bunch charge beams will be used to keep the photon count rate low and avoid pile up in the detector. We report here on the optics solutions, the expected channaling spectrum including background from bremmstrahlung and the use of a Compton scatterer for higher bunch charge operation.
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TUPOW050	Parametric X-rays at FAST	brilliance, electron, detector, scattering	1877
	T. Sen Fermilab, Batavia, Illinois, USA
	Funding: Fermilab is operated by Fermi Research Alliance LLC under DOE contract No. DE-AC02CH11359 We discuss the generation of parametric X-rays (PXR) in the photoinjector at the new FAST facility at Fermilab. Detailed calculations of the intensity spectrum, energy and angular widths and spectral brilliance with a diamond crystal are presented. We also report on expected results with PXR generated while the beam is channeling. The low emittance electron beam makes this facility a promising source for creating brilliant X-rays.
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TUPOW051	Optimization of Electron Beam and Laser Pulse Alignment and Focusing at Interaction Point for a Compact FEL Based Inverse-Compton Scattering X-Ray Source	electron, laser, FEL, undulator	1881
	P. Niknejadi, J. Madey University of Hawaii, Honolulu,, USA
	Funding: This work was funded under the Department of Homeland Security Grant No. 2010-DN-077-ARI045. In July 2015, the first beam of 10 keV X-rays from our FEL based inverse-Compton scattering X-ray source was detected.* In this setup, 3 micron laser pulses at 2.856 GHz repetition rate from a free electron laser are collided head-on with 40 MeV electron bunches driving the laser. To attain our objective the ebeam was required to have 1) a tight focus at the X-ray interaction point, 2) vertical and horizontal envelopes matched to the downstream undulator, 3) minimized transverse dimensions for low ionizing radiation. Optimization of these quantities required information on the evolution of the beam profiles between the beam spot images on the available insertable screens, leading to the need for a simulator to accurately trace the beam profiles through the system. A simulator was developed and used to optimize the system Twiss parameters by comparing the effectiveness of the beam profiles computed by fitting the profiles to the observed beam spot images along the beamline for different cathode positions. This method proved to be considerably more flexible and effective than the more traditional quadrupole scan technique. Summery of the designed system and results are provided. * John M. J. Madey, ARI final report, December 2015.
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TUPOW052	LLNL Laser-Compton X-ray Characterization	laser, electron, simulation, background	1885
	Y. Hwang, T. Tajima UCI, Irvine, California, USA G.G. Anderson, C.P.J. Barty, D.J. Gibson, R.A. Marsh 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 Laser-Compton X-rays have been produced at LLNL, and results agree very well with modeling predictions. An X-ray CCD camera and image plates were calibrated and used to characterize the 30 keV X-ray beam. A resolution test pattern was imaged to measure the source size. K-edge absorption images using thin foils confirm the narrow bandwidth of the source and offer electron beam diagnostics.
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TUPOW055	Coronagraph Measurements on the Australian Synchrotron Storage Ring Optical Diagnostic Beamline	synchrotron, background, extraction, diagnostics	1895
	M.J. Boland, Y.E. Tan SLSA, Clayton, Australia T.M. Mitsuhashi KEK, Ibaraki, Japan
	A coronagraph was constructed on the Optical Diagnostic Beamline at the Australian Synchrotron to observe the tails of the stored beam and the injected beam on the first few turns. Some results are presented with special emphasis on the limitation of the dynamic range due to the quality of the synchrotron light extraction mirror.
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TUPOY018	FLUKA Simulations for Radiation Protection at 3 Different Facilities	neutron, proton, ion, radiation	1940
	R. Rata, S.C. Lee IIAA, Huddersfield, United Kingdom R.J. Barlow University of Huddersfield, Huddersfield, United Kingdom
	FLUKA Monte Carlo Code is a transport code widely used in radiation protection studies. The code was developed in 1962 by Johannes Ranft and the name stands for FLUktuierende Kaskade (Fluctuating Cascade). The code was developede for high-energy physics and it can track 60 different particles from 1keV to thousands of TeV. It can be applied to accelerator design, shielding design, dosimetry, space radiation and hadron therapy. For particle therapy, FLUKA uses various physical models, all implemented in the PEANUT (Pre-Equilibrium Approach to Nuclear Thermalization) framework. The investigation was made for three different facilities : the Clatterbridge Cancer Centre, the Christie Hospital and the OpenMeD facility at CERN. We calculated the secondary dose distributed to the patient, in case of Clatterbridge Cancer Centre, and to the workers in case of the Christie Hospital and OpenMeD, and to investigate whether the shielding methods meet the existing radiation protection requirements and that the doses to the staff are kept As Low As Reasonably Achievable (ALARA).
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TUPOY046	Study on NRF-CT Imaging by Laser Compton Backscattering Gamma-rays in UVSOR	target, detector, laser, resonance	2007
	H. Ohgaki, I. Daito, T. Kii, H. Zen Kyoto University, Kyoto, Japan T. Hayakawa, T. Shizuma JAEA, Ibaraki-ken, Japan M. Katoh, J. Yamazaki UVSOR, Okazaki, Japan Y. Taira, H. Toyokawa AIST, Tsukuba, Japan
	Funding: This work was supported by JSPS KAKENHI Grant Number 26289363, 24340060 and the Joint Studies Program (2014) of the Institute for Molecular Science. Monochromatic gamma-ray beam in MeV energy region is suitable for non-destructive inspection of high density and massive objects because of its high penetrability. A specific nuclide can be detected by the process of Nuclear Resonance Fluorescence (NRF). A non-destructive inspection of Special Nuclear Materials hidden in a container cargo using NRF is proposed by Bertozzi. Non-destructive detection of Pu inside of a spent nuclear fuel rod is also proposed for management of radioactive wastes, nuclear material accounting and safeguards. We have developed 2D NRF imaging by using quasi-monochromatic gamma-ray beam in MeV energy region generated by Laser Compton Backscattering (LCS) method** and proposed to develop an NRF-CT image in the ELI-NP where a high intensity LCS beam can be available in near future. To demonstrate and finalize the measurement system of the NRF-CT imaging by using LCS gamma-ray beam, we have started a study on NRF-CT imaging at the new LCS beamline in UVSOR. The LCS beamline can generate 5.4 MeV LCS gamma-rays with a flux of 1×10⁷ photons/s. We have measured the 5.291 MeV NRF gamma-rays from a lead target in this beamline and tried to take a NRF-CT image. * W. Bertozzi et al., Nucl. Inst. Meth. B241, 820-825 (2005). B. Ludewigt et al., Proc. of 2010 ANS meeting (2010). * H. Toyokawa et al., JJAP, 50, 100209 (2011).
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WEOCA03	Simulating Proton Synchrotron Radiation in the Arcs of the LHC, HL-LHC and FCC-hh	optics, simulation, radiation, electron	2073
	G. Guillermo Cantón, F. Zimmermann CERN, Geneva, Switzerland D. Sagan Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	At high proton-beam energies, beam-induced synchrotron radiation is an important source of heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can give rise to an electron cloud. We use the Synrad3D code developed at Cornell to simulate the photon distributions in the arcs of the LHC, HL-LHC, and FCC-hh. Specifically, for the LHC we study the effect of the "sawtooth" chamber, for the HL-LHC the consequences of the ATS optics with large beta beating in the arcs, and for the FCC-hh the effect of a novel beam-screen design, with a long slit surrounded by a "folded" ante-chamber.
	Slides WEOCA03 [0.329 MB]
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOCA03
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WEOAB03	Photoemission Properties of LaB6 and CeB6 Under Various Temperature and Incident Photon Energy Conditions	cathode, laser, electron, vacuum	2088
	K. Morita, T. Katsurayama, T. Kii, K. Masuda, T. Murata, K. Nagasaki, T. Nogi, H. Ohgaki, S. Suphakul, K. Torgasin, H. Yamashita, H. Zen Kyoto University, Kyoto, Japan
	Recently, thermionic cathode materials such as LaB6, Ir5Ce and dispenser cathodes have been also used as photocathode since they have low work function, reasonably high quantum efficiency, and long lifetime,. However, the effect of cathode temperature and laser wavelength on quantum efficiency is known only for limited conditions. Although it is expected to be able to lengthen the required wavelength of photocathode drive laser by heating cathodes, laser with photon energy under the work function has not been tested. Revealing them enables us to design the cost minimum accelerators. In this research, photoemission properties of LaB6 and CeB6 with various excitation photon energies will be investigated under various temperatures of the materials. Those materials have similar work function, but CeB6 have one order of magnitude smaller Richardson constant than LaB6*. By comparing photoemission properties of these materials, impact of Richardson constant on the photoemission properties will be investigated. S. Thorin et al. Proc of FEL2009, 310 D. Satoh et al. Proc of IPAC2014, 679 * J.M. Lafferty, J. Appl. Phys. 22, (1951), 299
	Slides WEOAB03 [0.996 MB]
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WEPMB019	Magnetic Fields in Bulk, Film, and Multilayer Superconductors in Front of a Multi-turn Coil	experiment	2164
	T. Kubo KEK, Ibaraki, Japan
	Funding: JSPS Young Scientists(B) #26800157, JSPS Challenging Exploratory Research #26600142, MEXT Photon and Quantum Basic Research Coordinated Development Program The magnetic field distribution formulae in a bulk superconductor, a superconducting film, and an SIS multilayer structure in front of a multi-turn coil are derived, which may be useful for a detailed analysis in a vortex field measurement by using the third harmonic method. * See for example the invited oral presentation by T. Kubo, "Theory of multilayer coating for proof-of-concept experiments", at SRF2015 ** C.Z.Antoine et al., Appl. Phys. Lett. 102, 102603 (2013)
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WEPMB025	Fabrication of Superconducting Spoke Cavity for Laser Compton Scattered Photon Sources	cavity, laser, simulation, linac	2177
	M. Sawamura, R. Hajima QST, Tokai, Japan H. Hokonohara, Y. Iwashita, H. Tongu Kyoto ICR, Uji, Kyoto, Japan T. Kubo, T. Saeki KEK, Ibaraki, Japan
	Funding: The work is supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan. We have launched a 5-year research program to develop superconducting spoke cavity for laser Compton scattered (LCS) photon sources. For realizing a wide use of LCS X-ray and γ-ray sources in academic and industrial applications, we adopt the super-conducting spoke cavity to electron beam drivers. The spoke cavity has advantages such as relative compactness in comparison with an elliptical cavity of the same frequency, robustness with respect to manufacturing inaccuracy due to its strong cell-to-cell coupling, the better packing in a linac to install couplers on outer conductor. On the other hand the spoke cavity has disadvantage of more complicated structure than an elliptical cavity. Though our proposal design for the photon source consists of the 325 MHz spoke cavities in 4K operation, we have begun to fabricate the half scale model of 650 MHz spoke cavity in order to accumulate our cavity production experience by effective utilization of our limited resources. In this paper, we present our fabrication status.
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WEPMR040	HOM Absorber Study by Photon Diffraction Model	HOM, cavity, damping, SRF	2360
	C. Xu, I. Ben-Zvi, V. Ptitsyn, P. Takas, W. Xu BNL, Upton, Long Island, New York, USA I. Petrushina SUNY SB, Stony Brook, New York, USA B. P. Xiao SBU, Stony Brook, New York, USA
	Photon diffraction model (PDM) is one of the most promising candidates to study High Order Mode (HOM) power absorption on absorbing materials for high current SRF cavities. Because at very high frequency (>10GHz), the wavelengths of HOMs are much smaller compared with accelerators dimension, the phase of those HOM will be negligible. Meanwhile, Finite Element Method (FEM) cannot lend a high resolution on evaluation the HOM field patterns due to limited meshing capability. This PDM model utilizes Monte Carlo simulation to trace the ray diffusive reflection in a cavity. This method can directly estimate the power absorption on the cavity and absorber wall. This method will help design the HOM damper setup for eRHIC HOM damper. In this report, we evaluate HOM absorption on the cavity wall with different absorber setup and give a possible solution for power damping scheme for high frequency HOMs.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR040
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WEPMR047	Overall Design of Magnet Girder System for Heps-Tf	alignment, controls, emittance, storage-ring	2383
	H. Wang, L. Gong, C.H. Li, S. Li, H. Qu, Z. Wang, L. Wu IHEP, Beijing, People's Republic of China
	HEPS-TF is the test facility of HEPS (High Energy Pho-ton Source) of China. The magnet girders are used for supporting and positioning of the magnets. As the beam emittance is very low, the girder must has high adjusting precision and high stability. Besides, the girder should also be beam-based aligned. For these issues, two girder systems are designed. Both of them use cam mover mech-anisms for precision adjustment. One has six cam mover mechanisms and another has eight. The design aim of the alignment accuracy between girders is within 50 μm, and the adjusting resolution is within 3μm. The design aim of the natural frequency is above 30 Hz. This paper will discuss the scheme selection and structural design of the girder systems.
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WEPMW010	Effect of Beamstrahlung on Bunch Length and Emittance in Future Circular e⁺e⁻ Colliders	radiation, collider, emittance, synchrotron	2438
	M.A. Valdivia García, F. Zimmermann CERN, Geneva, Switzerland
	In future circular e⁺e⁻ colliders, beamstrahlung may limit the beam lifetime at high energies, and increase the energy spread and bunch length at low energies. If the dispersion or slop of the dispersion is not zero at the collision point, beamstrahlung will also affect the transverse emittance. In this paper, we first examine the beamstrahlung properties, and show that for the proposed FCC-ee, the radiation is fairly well modelled by the classical formulae describing synchrotron radiation in bending magnets. We then derive a set of equations describing the equilibrium beam parameters in the presence of a nonzero dispersion at the collision point. An example case from FCC-ee will serve as an illustration.
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WEPMY040	Fabrication of Two Dimensional Nano-Scale Photocathode Arrays in Transparent Conductor for High Coherence Beam Generation	electron, laser, cathode, simulation	2645
	T. Shibuya TIT, Tokyo, Japan N. Hayashizaki RLNR, Tokyo, Japan M. Yoshida KEK, Ibaraki, Japan
	Electron beam quality for particle source of diffractometer is mainly characterized by transverse and longitudinal coherent length, beam current density and so on. In order to improve a transverse coherent length, it is practically essential to minimize electrons emission area size as small as possible. However, the size of photoemission area is limited by focused laser beam size on the surface of cathode, and the scale is several microns. Aim to get definite overlap between the focused laser and emitters for effective irradiation, as well as to realize generation of nano-scale size electron beam, nano-scale photocathode arrays in transparent conductor are essential. Therefore, I propose to fabricate the nano-scale emission area in replace of limiting the focused laser size on the photocathode for achieving high coherence beam. The fabrication process of this novel nano-scale emitter configuration and its fundamental properties are presented in this paper.
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WEPOR024	HPGe Detector Application on Monitoring Environmental Samples around the Accelerator	detector, simulation, software, monitoring	2725
	Y.D. Ding, Z.J. Ma, Q.B. Wang, M.Y. Yan, Q.J. Zhang IHEP, Bejing, People's Republic of China
	Massive experimental works are aimed to clarify the structure of detector including CT with X ray machine, determining the thickness of dead layer with collimating radioactive source and ect. Measuring structure and size of the detector by X-ray computed tomography, measur-ing the dead layer thickness of detector's front surface and side surface though collimated point source method, scanning the dead layer distribution of the entire detec-tor. A finite element analysis software name CST is used to simulate electric field distribution of the HPGe detec-tor. Calibrating the efficiency of HPGe detector by means of point source and soil standard matter, A Monte Carlo software called MCNP is used to simulate detector effi-ciency preliminarily according to the structure parame-ters of the factory, optimizing and verifying simulated results on the basis of measured results. At last, the com-parison of the simulated and the experimental data showed very good agreement.
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WEPOW011	BESSY II Supports an Extensive Suite of Timing Experiments	experiment, synchrotron, operation, timing	2840
	R. Müller, T. Birke, F. Falkenstern, K. Holldack, P. Kuske, A. Schälicke, D. Schüler HZB, Berlin, Germany H.G. Glass, R. Ovsyannikov BESSY GmbH, Berlin, Germany
	The synchrotron light source facility BESSY II has put top-up and a fast orbit feedback (FOFB) into operation in 2013. Both operational improvements have matured and turned out to be especially beneficial for the advanced timing opportunities supported at BESSY. In combination with very tight injection efficiency requirements a thorough understanding of top-up injections under all operational conditions has been developed. Consequently arbitrary bunch currents can be dialed in and maintained on demand. In standard mode, a very pure camshaft bunch is available both in general for laser pump/X-ray probe and for pseudo single bunch experiments at the MHz chopper beamline. 3 constant high current bunches support the FEMTOSPEX slicing facility. An additional bunch can be resonantly excited and pulse picked via custom orbit bumps at 3 different undulator beamlines (PPRE). Due to the FOFB the classical timing modes "single bunch" and "low alpha" feature an attractive pointing stability.
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WEPOW021	The Low Emittance Reconstruction of the Arc Section of the Photon Factory	emittance, dynamic-aperture, sextupole, lattice	2874
	K. Harada, Y. Kobayashi, N. Nakamura, K. Oide, H. Sakai, S. Sakanaka KEK, Ibaraki, Japan
	The present horizontal emittance of the Photon Factory (PF) ring is about 35.4 nmrad. By the reconstruction of the normal cells at the arc section, the emittance can be reduced to about 8 nmrad. The double number of the combined function short bending magnets are adopted and one present normal cell become two new normal cells. Although the lattice of the straight sections are not changed, the optics are optimized to reduce the non-linear effects of the sextupoles of the arc sections. By keeping the tune advance of the straight section as 3 for the horizontal direction and 2.5 for the vertical, the dynamic aperture as large as that of the present ring can be achieved with the magnetic errors. The difference of the optics of the straight sections are so little that the beam injection and the operation of the in-vacuum short-gap undulators can be maintained. The hardware design will be began as the next step for the realization of the plan. In this proceedings, the design, optimization and simulation results for the low emittance lattice are shown.
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WEPOW039	Preliminary Beam Loss Study of TPS during Beam Commissioning	injection, radiation, scattering, EPICS	2926
	C.H. Huang, J. Chen, Y.-S. Cheng, K.T. Hsu, K.H. Hu, D. Lee, C.Y. Liao, C.Y. Wu NSRRC, Hsinchu, Taiwan
	Taiwan photon source (TPS) is a 3rd generation and 3 GeV synchrotron light source in NSRRC. Several types of beam loss monitors (BLMs) such as RadFETs and PIN-diode BLMs are installed in the storage ring to understand the beam loss distribution and mechanism during the injection, decay mode, top-up operation and beam trip. Several RadFETs are also installed around the inserting devices to study the beam loss near the linear scalar. The preliminary beam loss study using RadFETs are PIN-diode BLMs in the storage will be summarized in this report.
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WEPOW042	Properties of Synchrotron Radiation from Segmented Undulators based on a Wigner Distribution Function	undulator, electron, brilliance, radiation	2933
	H.W. Luo, C.H. Lee NTHU, Hsinchu, Taiwan T.Y. Chung, C.-S. Hwang NSRRC, Hsinchu, Taiwan
	Three long straight sections with a double mini-βy lattice were designed in Taiwan Photon Source. For the purpose to understand whether the brilliance can be enhanced or not when two collinear undulators were installed in the double mini-βy. Therefore, the Wigner distribution function (WDF) is developed to calculate the brilliance in the double mini-βy lattice that is a natural way to describe a synchrotron radiation source. Herein, the brilliance is thereby calculable without a Gaussian approximation used in a conventional manner. Some important optical properties such as the degree of coherence can be directly calculated with this method. We use it as an example to investigate the properties of radiation from a segmented undulator.
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WEPOW045	Concepts for a Low Emittance-High Capacity Storage Ring for the Diamond Light Source	lattice, emittance, wiggler, dipole	2943
	R. Bartolini, G. Cinque, G. Evans, K. Sawhney, J. Zegenhagen DLS, Oxfordshire, United Kingdom
	The Diamond Light Source is investigating several paths for a possible machine upgrade to Diamond II. The exercise is driven by by a joint assessment of the science capabilities opened by a very low emittance ring and the machine design that will underpin them. The consultation is made on a beamline-by-beamline basis and has highlighted a significant preference for lattices that combine both a low emittance and large capacity for IDs.
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THPMB042	Residual Orbit Correction Studies for the FCC-hh	quadrupole, dipole, alignment, hadron	3332
	D. Boutin, B. Dalena CEA/IRFU, Gif-sur-Yvette, France A. Chancé, J. Payet CEA/DSM/IRFU, France B.J. Holzer, R. Martin, D. Schulte CERN, Geneva, Switzerland
	The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the three options considered for the next genera-tion accelerator in high-energy physics as recommended by the European Strategy Group []. Preliminary studies have started to estimate the design parameters of FCC-hh. One of these studies is the calculation of the residual orbit in the arcs of the collider. This is very important for the evaluation of the alignment tolerances of the quadru-poles used in the arcs, the dimensioning of the correctors and of the beam screen. Moreover it has an impact on the dynamic aperture of the ring and the field tolerances of the arc multipoles. To perform the simulations, the beam transport code MADX has been used. Systematic studies of the residual orbit and of the correctors' strength de-pendence on the magnets misalignment or field errors are presented and discussed. [] A. Ball et al., EDMS-0134202.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB042
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THPMR017	Resonance Island Experiments at BESSY II for User Applications	undulator, operation, resonance, experiment	3427
	P. Goslawski, J. Feikes, K. Holldack, A. Jankowiak, M. Ries, M. Ruprecht, A. Schälicke, G. Wüstefeld HZB, Berlin, Germany R. Ovsyannikov BESSY GmbH, Berlin, Germany
	Beam storage close to a tune resonance (Qx = 1/3, 1/4) can generate resonance island buckets in the x,x' phase space providing a second stable island orbit winding around the standard orbit. Experiments with such an operation mode have been conducted at BESSY II and the Metrology Light Source (MLS),. The two orbits are well separated, with good life time and stability. Such operation mode will offer additional operation flexibility and allows users to choose their radiation source point from one or the other orbit. It has the potential to fulfill simultaneously conflicting user demands, e.g., high vs. low beam current and single or few bunch filling vs. multibunch filling. We discuss the required beam optics setup and present successful measurements taken at photon beamlines at BESSY II. P. Goslawski et al., "Bunch Separation by Transverse Resonance Island Buckets", ESLS XXIII Workshop, 2015, Villigen, Switzerland. ** M. Ries et al., Proc. IPAC 2015, Richmond, USA, MOPWA021.
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THPMW017	Phase Shifter Power Supply Design	controls, simulation, electron, power-supply	3576
	Y.T. Li, K.-B. Liu, B.S. Wang, Y.S. Wong NSRRC, Hsinchu, Taiwan
	Taiwan Photon Source is an interdisciplinary project. The phase-shift magnet is used to connect the radiation phase between two EPU48s. The power supply for this phase-shift magnet is a key element to determine the phase shift quality. In this report, the theory of the designed circuit is firstly introduced, and then a comparison simulation result and actual measurement is summarized to prove the correctness of theoretical analysis and circuit design.
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THPMY001	Design and R&D for the SPring-8 Upgrade Storage Ring Vacuum System	vacuum, storage-ring, laser, radiation	3651
	M. Oishi, T. Bizen, H. Ohkuma, M. Shoji, S. Takahashi, K. Tamura, Y. Taniuchi JASRI/SPring-8, Hyogo-ken, Japan
	Conceptual design report for the SPring-8 upgrade project (SPring-8-II) was published in November of 2014. Vacuum system for the targeted storage ring should handle some fateful boundary conditions, such as miniaturization of vacuum chamber and increase in number of photon absorbers resulting from the multi-bend achromat configuration. Furthermore, reuse of the existing tunnel brings the severe packing factor issue of vacuum components and the time constraints issue of one-year blackout. Considering the above circumstances, a concept of 12-m long vacuum chamber with welded integral structure was proposed to omit in-situ baking. The 12-m long chamber will be evacuated to ultra-high vacuum by ex-situ baking followed by NEG activation, and moved to the tunnel with special thin gate valves at both ends. Recently, the chamber material has been changed from aluminum alloy to stainless steel (SS) from the viewpoints of elimination of aluminum-SS transition space, beam vibration suppression, and superior outgassing property. Trial production of SS chamber is proceeding to establish appropriate manufacturing processes, while focusing on the accuracy of dimension and magnetic permeability.
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THPMY018	Benchmarking and Calibration of Monte Carlo Vacuum Simulations with SynRad and MolFlow+	vacuum, storage-ring, experiment, scattering	3695
	J.A. Carter ANL, Argonne, Ilinois, USA
	The APS-Upgrade project is using SynRad and MolFlow+ to evaluate the vacuum system design for the future 6 GeV, 200 mA APS-Upgrade storage ring. The goal of this work is to explore PSD outgassing predictions from the two programs in order to build confidence in pressure calculations for the APS-U storage ring vacuum system. A study is performed on calibrating PSD measurements for aluminum vacuum chambers and then applying them to APS-U vacuum system calculations. The study reveals that a PSD measurement may not reveal a single unique behavior for a vacuum material and that multiple sources should be considered for vacuum calculations.
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THPOR020	Status of VEPP-4M Collider	experiment, injection, storage-ring, detector	3818
	E.B. Levichev, O.I. Meshkov, P.A. Piminov, A.N. Zhuravlev BINP SB RAS, Novosibirsk, Russia
	At present the VEPP-4 storage ring facility provides varied experimental programs including HEP, nuclear physics, synchrotron radiation, polarized electron/positron beam research, etc. Until now, the studies were mainly performed at the beam energy below 2 GeV but a strong interest of experimentalists encourages us to increase the beam energy up to 5 GeV. Reliable and high-performance operation at high energy is a challenge for the machine. Here we discuss the recent experimental results at the low energy, and prospects and constraints of the energy ramp.
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THPOR030	Commissioning and First Performance Studies of a Single Vertical Beam Halo Collimation System at ATF2	background, collimation, simulation, wakefield	3844
	N. Fuster-Martínez, A. Faus-Golfe IFIC, Valencia, Spain P. Bambade, A. Faus-Golfe, S. Wallon, R.J. Yang LAL, Orsay, France K. Kubo, T. Okugi, T. Tauchi, N. Terunuma KEK, Ibaraki, Japan I. Podadera, F. Toral CIEMAT, Madrid, Spain T. Tauchi, N. Terunuma Sokendai, Ibaraki, Japan
	A single vertical beam halo collimation system has been installed in the ATF2 beamline to reduce the background that could limit the precision of the diagnostics located in the post-IP beamline. On this paper the commissioning and first performance studies of a single vertical beam halo collimation system are reported. Furthermore realistic efficiency studies have been done using the simulation code BDSIM and compared with the first experimental tests.
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THPOW004	Pulse Response Measurements of NEA Photocathodes at Different Laser Wavelengths	laser, electron, cavity, cathode	3931
	M.A. Dehn, K. Aulenbacher, V. Bechthold IKP, Mainz, Germany
	For high average electron beam currents the length of the electron bunches must match the acceptance of the accelerator. At Johannes Gutenberg-University Mainz we are able to measure the longitudinal pulse response of NEA photocathodes (GaAs) under photo excitation of different wavelengths. A time resolution of < 2 ps at a beam energy of 100 keV is achieved, furthermore, a high dynamic range allows to investigate long ranging tails of the response (longitudinal halo). This serves to identify the best possible operation mode for high current photo sources.
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THPOW016	Transverse Energy Spread Measurements from GaAs Photocathodes at Variable Wavelengths	electron, cathode, detector, laser	3964
	T.C.Q. Noakes, R. Beech, L.B. Jones, B.L. Militsyn STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom H.E. Scheibler, A.S. Terekhov ISP, Novosibirsk, Russia
	The transverse energy spread spectrometer (TESS) is an instrument specially developed at Daresbury Laboratory to measure the intrinsic transverse and longitudinal energy distributions from photocathode materials. Early work on the instrument has focussed on its use for the characterisation of GaAs photocathodes such as those commonly used in DC photoinjectors. More recently work has been conducted to extend the range of materials which can be evaluated using this apparatus, in particular by incorporating a monochromated white light source. New results are presented using the white light source to measure the energy spread of a GaAs photocathode across a range of different wavelengths to evaluate how this changes with excess energy.
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THPOW025	Photocathode Growth and Characterization Advances at Cornell University	electron, emittance, cathode, gun	3990
	L. Cultrera, A.C. Bartnik, I.V. Bazarov, B.M. Dunham, C.M. Gulliford, H. Lee, R.A. Lipton, T.P. Moore Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
	Alkali-antimonides based photocathodes have demonstrated outstanding performance in high brightness electron beam production suitable for a wide range of applications such as FELs, ERLs and UED and for use in photomultiplier devices with picosecond resolution aimed at photon counting application in medicine and High Energy Physics. The photocathode laboratory at Cornell University is dedicated to studying the growth procedures and characterizing the properties in a wide range of photocathodes materials. Different experimental arrangements and alkali metal sources have been successfully explored to date to synthesize photosensitive materials. Recent work on commissioning a new growth chamber equipped with effusion cells loaded with pure metal allowing uniform deposition over large area substrates resulted on successful growth of photocathodes with extended sensitivity in the IR part of the spectrum and high efficiency alkali antimonides containing Rb metal. This and other advances aimed at demonstrating superior photocathodes will be presented.
DOI •	reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW025
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THPOW030	ELI Eectron Beam Line for Laser-plasma-driven Undulator X-ray Source	electron, undulator, quadrupole, laser	4005
	A.Y. Molodozhentsev KEK, Ibaraki, Japan L. Pribyl Czech Republic Academy of Sciences, Institute of Physics, Prague, Czech Republic
	ELI LUX experiment of the ELI-Beamlines Project is based on electron beam, accelerated by the laser plasma wakefield. ELI LUX aims to deliver for users the X-ray beams with radiation length (0.4-4.5)nm and the peak brilliance up to 10²³ photons/(s mrad2 mm2 0.1% B.W.), which makes this source comparable with modern synchrotron sources. To provide small transverse size of the electron beam and small transverse beam divergence in the undulator, permanent quadrupole magnets with high gradient of the magnetic field up to 510 T/m are used in the electron beam line. In frame of this report we present main features of the designed electron beam line. 3D modeling of the magnetic field in the quadrupole magnets has been performed. Effects of the chromatic and spherical aberrations are taken into consideration. The electron beam dynamic is studied by using symplectic integration though the 3D field maps of the permanent quadrupole magnets. Effects of the space charge of the electron beam, beam collimation, injection and alignment errors and realistic field errors are discussed. Finally parameters of the photon beam, generated in compact undulator, are presented in this report.
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THPOW035	Statistical Analysis Package for the Opearion Monitoring at the TLS	operation, database, Windows, target	4019
	Y.K. Lin, H.H. Chen, H.C. Chen, S.J. Huang, C.H. Kuo, A.P. Lee, J.A. Li NSRRC, Hsinchu, Taiwan
	Machine operation parameters and interruptions to user beam at Taiwan Light Source (TLS) and Taiwan Photon Source (TPS) are recorded in databases. The data retrieve to TLS uses the File Transfer Protocol (FTP) with two separated databases 10 Hz and 0.1 Hz for quick or detail data analysis options. TPS data storage uses the open source database PostgreSQL. A statistical analysis package HISTORY has been writ-ten in Microsoft Visual C to perform operation monitor-ing and data mining. Operation and failure statistics func-tions are produced for performance evaluation and User Administration & Promotion Office user time statistics.
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THPOW037	Simulated and Measured Magnetic Performance of a Double APPLE-II Undulator at the Canadian Light Source	undulator, multipole, polarization, dipole	4025
	C.K. Baribeau, L.O. Dallin, J.M. Helfrich, T.M. Pedersen, M.J. Sigrist, W.A. Wurtz CLS, Saskatoon, Saskatchewan, Canada
	Assembly and shimming are underway for a double APPLE-II type elliptically polarized undulator (i.e. two magnet arrays installed side by side on a single support structure) at the Canadian Light Source. The device is planned to be installed in spring 2017. Extensive preparation was done prior to device assembly, particularly in development of a simulated annealing algorithm for magnet virtual shimming, as well as assembly procedures that minimized positional errors in the installed magnet blocks. In this paper we present measurements taken throughout the shimming process, and compare with predictions from a RADIA model where each magnet block was magnetized uniquely according to individual Helmholtz coil measurements.
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THPOW048	Optimization of a Multipole Wiggler for Tps	wiggler, electron, radiation, permanent-magnet	4050
	J.C. Jan, C.-H. Chang, T.Y. Chung, J.C. Huang, C.-S. Hwang, C.Y. Kuo NSRRC, Hsinchu, Taiwan
	Taiwan Photon Source (TPS) is a synchrotron radia-tion facility with electron energy 3 GeV that was commissioned in 2015. Taiwan Light Source (TLS) with electron energy 1.5 GeV concurrently provides user time. Three beam lines of TLS supply photons of energy 6-18 keV for user experiments; these beam lines are served with an in-achromatic superconduct-ing wiggler (IASW, 3.1 T). This superconducting inser-tion device has the disadvantages of complicated maintenance and operation. A traditional multipole wiggler (MPW) magnet of hybrid type is hence planned to be installed in TPS to cover the range of photon energy of IASW for user experiments. For the design of the magnetic circuit, the side block and the extreme block are arranged surrounding a Permendur Vanadium cobalt steel pole that enhances the field strength and good field region of a MPW magnet. The dynamic integral field and the demagnetizing field of MPW magnet were estimated. The optimization of the pole dimensions and photon characteristics were simu-lated and are discussed in this work.
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THPOW049	Status of Insertion Devices at Taiwan Photon Source	undulator, vacuum, radiation, polarization	4054
	T.Y. Chung, C.-H. Chang, C.H. Chang, M.-S. Chiu, J.C. Huang, C.-S. Hwang, J.C. Jan, C.-C. Kuo, Y.-C. Liu, F.H. Tseng, C.K. Yang NSRRC, Hsinchu, Taiwan
	The storage ring of Taiwan Photon Source (TPS) has eighteen short straight sections (length 7 m) and six long straight sections (length 12 m). In phase I, three elliptically polarized undulators of type APPLE II and seven in-vacuum undulators, which included four in-vacuum undulators and two elliptically polarized undulators in three double mini-βy sections, were installed. Commissioning of the insertion devices began in 2015 November. The influence of insertion devices on the electron beam and the results after compensation are presented. Problems during the commissioning induced by the electron beam and by radiation, and their solutions, are also explained. For insertion devices in phase II and for devices developed in TPS, the preliminary designs are presented herein, to cover from the VUV to the hard X-ray region.
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THPOY049	Helical Undulator as a Source of Spectromicroscopy Beamline of ILSF	polarization, undulator, electron, radiation	4217
	S. Amiri, A. Gholampour, M. Jafarzadeh, M. Lamehi, J. Rahighi ILSF, Tehran, Iran M. Lamehi, J. Rahighi IPM, Tehran, Iran
	Regarding user requirements of spectromicroscopy beamline such as high flux, small spot size, linear and circular polarization light, a helical undulator have been chosen as a source for this beamline. Radiation properties of the source e.g. flux, flux density, brilliance, size and divergence of the photon beam, power, power density, angular distribution of power and flux on the axis of the undulator have been considered by theoretical formula and using SPECTRA code. At the circular polarization, the first harmonic covers the energies in the 100-1300 eV range and for the linear polarization energy ranges, 100-1000 eV and 1000-1500 eV, are provided by the first and third harmonics respectively. In the case of circular and linear polarization mode, maximum flux in the central cone for maximum undulator strength are 4.5 × 10¹⁶ (ph/s) at kX=ky=3.6 and 2.4 × 10¹⁶ (ph/s) at K=5. * James A. Clarke, "The science and technology of undulators and wigglers", 2004. ** H. Onuki, P. Elleaume, "WIGGLERS UNDULATORs and their APLICATIONS", 2003.
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THPOY050	Time Response of a Gridded X-ray Beam Ionization Chamber	ion, electron, experiment, radiation	4220
	Y.H. Xu, Z.H. Sun DongHua University, Songjiang, People's Republic of China D.V. Campen, W.J. Corbett SLAC, Menlo Park, California, USA C.L. Li East China University of Science and Technology, Shanghai, People's Republic of China W.J. Zhang University of Saskatchewan, Saskatoon, Canada
	Recently, Quick-Scanning Extended X-ray Absorption Spectroscopy (QEXAS) has become an important tool for in-situ characterization of materials and measurement of associated electronic structure. In this case the time response of the ionization chamber affects the measurement resolution and therefore overall performance of the QEXAS system. Common parallel-plate ionization chambers have a step-response rise time of about 0.1 sec, which does not meet the requirements of QEXAS. To speed up the response, we constructed a gridded ionization chamber with variable bias voltage and optional background gas (N2 or He, respectively). To characterize the system we used a high-frequency beam chopper upstream of the ionization chamber and a high-speed, low-noise preamplifier to measure the step response of the chamber as a function of bias voltage and background gas conditions.
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MOPMB010

Compton Polarimetry at ELSA - Beamline and Detector Optimization

polarization, laser, electron, detector

95

R. Koop, W. Hillert, M.T. Switka
ELSA, Bonn, Germany

Funding: Work supported by DFG within CRC TRR16
The Electron Stretcher Facility ELSA provides a polarized electron beam with energies of 0.5 - 3.2 GeV for double polarization hadron physics experiments. Monitoring the vertical electron polarization by Compton polarimetry in the stretcher ring has several advantages over the established polarization measurement by Moeller polarimetry. The Compton polarimeter setup presented consists of a 40 W cw disk laser featuring two polarized photon beams colliding head-on with the stored electron beam in ELSA. A silicon strip detector measures the vertical intensity profile of the backscattered photons. The reversal of handedness of the laser beam's circular polarization results in a polarization dependent vertical shift of this profile. From a calibration using time dependent polarization build-up due to the Sokolov-Ternov effect, the polarization degree of the electron beam can be extracted. After recent laser repairs as well as beamline and detector modifications, first measurement attempts of the electron's polarization degree were conducted. The performance of the beamline and first measurements are presented.

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MOPMB028

Development of Beam Diagnostic System for the SPring-8 Upgrade

diagnostics, radiation, beam-diagnostic, emittance

149

H. Maesaka, T. Ohshima, Y. Otake
RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
H. Dewa, T. Fujita, K. Kobayashi, M. Masaki, S. Matsubara, T. Nakamura, S. Sasaki, S. Takano
JASRI/SPring-8, Hyogo-ken, Japan

The goal of the beam diagnostic system for the SPring-8 upgrade is to deliver brilliant X-rays enabled by the new low-emittance ring to experimental stations with ultimate stability. Developments of accurate electron and photon beam position monitors (EBPM and XBPM, respectively) with both short and long-term stability are the most critical. The EBPM sensitivity is also crucial for low-current beam commissioning to accomplish the first beam storage in the ring. We designed a button electrode to obtain sufficiently high-intensity signals while suppressing high-Q trapped modes leading to impedance and heating issues. We also designed a precise EBPM block and a rigid support to achieve mechanical accuracy and stability. Another challenge is the development of a reliable and stable XBPM, which should be an accurate reference for an orbit feedback without any photon-energy dependences. A significant improvement of a blade-type XBPM or an invention of a novel XBPM detecting the core of an intense X-ray beam are necessary. The other diagnostic instrumentations can be utilized for the new ring with minor improvements.

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MOPMB029

Development Status of Linear Focal Cherenkov Ring Camera

electron, vacuum, laser, experiment

152

K. Nanbu, T. Abe, H. Hama, F. Hinode, S. Kashiwagi, T. Muto, I. Nagasawa, H. Saito, K. Takahashi, C. Tokoku
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

Linear focal Cherenkov ring camera (LFC-Camera) has been developed for single shot measurement of longitudinal phase space distribution of quasi-relativistic electron beam, where the electron's velocity still depends on its energy. The LFC-camera employs velocity dependence of opening angle of Cherenkov light produced by electron beam to observe its energy (momentum) distribution. Since the Cherenkov light contains the time information if the radiator medium is thin enough, we can get the longitudinal phase space distribution measuring both time and energy spectra simultaneously using a streak camera. We employ a thin silica aerogel with water-free hydrophobic treatment as Cherenkov radiator. We have evaluated characteristics of the silica aerogel radiator, and demonstration of the LFC-camera at a beam diagnosis section of t-ATCS is being proceeded.

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MOPMR033

Characterization of Beam Properties Using Synchrotron Light at Taiwan Photon Source

synchrotron, booster, storage-ring, injection

316

C.Y. Liao, Y.-S. Cheng, K.T. Hsu, K.H. Hu, C.-C. Kuo, H.-J. Tsai, C.Y. Wu
NSRRC, Hsinchu, Taiwan

Taiwan Photon Source (TPS) is a third-generation 3-GeV synchrotron light facility, located in National Synchrotron Radiation Research Center (NSRRC) at Hsinchu Science Park. After overcoming many challenges, the storage beam current attained 520 mA in 2015 December. The synchrotron light monitors, including X-ray and visible light, are important diagnostic tools to characterize the various machine conditions. The booster beam dynamics during ramping and the beam properties of the storage ring were studied with synchrotron light. The results of measurements are presented in this report.

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MOPOR016

Impedance Study with Single Bunch Beam at Taiwan Photon Source

impedance, storage-ring, synchrotron, vacuum

630

C.-C. Kuo, P.J. Chou, K.T. Hsu, K.H. Hu, C.C. Liang, C.Y. Liao, Z.K. Liu, H.-J. Tsai, F.H. Tseng
NSRRC, Hsinchu, Taiwan

The impedance at Taiwan Photon Source was investigated. The effects of bunch current such as a tune change, a synchronous phase shift and a bunch lengthening under operation conditions at various stages were measured; the machine impedances were deduced. This report presents the results with insertion devices in various configurations.

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MOPOW010

The Superconducting Soft X-ray Free-Electron Laser User Facility FLASH

FEL, operation, laser, electron

729

M. Vogt, J. Feldhaus, K. Honkavaara, J. Rönsch-Schulenburg, S. Schreiber, R. Treusch
DESY, Hamburg, Germany

FLASH, the superconducting free-electron laser at DESY delivers up to several thousand photon pulses per second with wavelengths ranging from 52 nm down to as low as 4.2 nm and with pulse energies of up to 500 uJ to photon users at the FLASH1 beamline. In 2014 and 2015 a second beamline, FLASH2, has been commissioned in parallel to user operation at FLASH1. FLASH produces bunch trains of up to 800 bunches in 0.8 ms with a train repetition rate of 10 Hz. Each train can be split in sub-trains for FLASH1 and FLASH2, such that both beamlines receive bursts of bunches with full 10 Hz. Operational highlights are the latest SASE energy record of 600 uJ at 15 nm in FLASH2, and the first simultaneous SASE lasing of three undulator systems: FLASH1 (13.7 nm), sFLASH (38 nm), and FLASH2 (20 nm). sFLASH is the seeding experiment in the FLASH1 beamline. Moreover we will report on recent technical and operational improvements. A major success is the improved reliability and stability of the whole facility with shorter SASE tuning times.

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MOPOW012

Transverse Coherence and Fundamental Limitation on the Pointing Stability of X-ray FELs

FEL, radiation, electron, emittance

735

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

The radiation from SASE FEL has always limited value of the degree of transverse coherence*. When transverse size of the electron beam significantly exceeds diffraction limit, the mode competition effect does not provide the selection of the ground mode, and spatial coherence degrades due to contribution of the higher azimuthal modes. An important consequence of this effect are fluctuations of the spot size and pointing stability of the photon beam**. These fluctuations are fundamental and originate from the shot noise in the electron beam. The effect of pointing instability becomes more pronouncing for shorter wavelengths. We analyze in detail the case of optimized SASE FEL* and derive universal dependencies applicable to all operating and planned x-ray FELs. We show that the hard x-ray FELs driven by low energy beams may exhibit poor spatial coherence and bad pointing stability.
* E.L. Saldin, E.A. Schneidmiller and M.V. Yurkov, Opt. Commun. 281(2008)1179.
** E.A. Schneidmiller and M.V. Yurkov, Proc. FEL2015 Conference, Daejeon, Korea, 2015, TUP021.

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MOPOW013

Application of Statistical Methods for Measurements of the Coherence Properties of the Radiation from SASE FEL

radiation, FEL, undulator, electron

738

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

Radiation of the SASE FEL operating in the linear regime possesses the properties of completely chaotic polarized light which happens due to start up of the amplification properties from the shot noise in the electron beam*. One of the features of this statistical object is that probability distribution of the radiation pulse energy follows gamma distribution. Parameter of this distribution is the number of modes in the radiation pulse which is equal to inverse deviation of the energy fluctuations. Statistical analysis of the radiation energies measured within different spatial apertures allows us to determine the number of longitudinal and transverse modes. In addition, knowledge of the saturation length allows to determine the duration of the lasing part of the electron bunch, photon pulse duration, and coherence time**. Knowledge of the number of transverse modes allows one to determine the degree of transverse coherence. In this report we present theoretical background of the proposed method and experimental results obtained at free electron laser FLASH.
* E.L. Saldin, E.A. Schneidmiller and M.V. Yurkov, Opt. Commun. 148 (1998) 383.
** C. Behrens et al., Phys. Rev. ST Accel. Beams 15 (2012) 030707.

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MOPOW014

Measurements of Ultrasmall Charges with MCP Detector in FLASH Accelerator

detector, electron, undulator, laser

741

O.I. Brovko, A.Yu. Grebentsov, A.V. Shabunov, E. Syresin
JINR, Dubna, Moscow Region, Russia
S. Schreiber, M.V. Yurkov
DESY, Hamburg, Germany

Structure of the dark current passed through the undulator is a matter of great concern. Two effects can contribute to the dark current: emission of electrons from "hot" spots in the gun, and generation of "ghost" bunches due to possible leakage of the photoinjector laser. MCP based photon detector has been used for measurements of radiation energy from electron bunch. For small radiation densities the light is detected by direct illumination of the MCP plate, and for large densities a small angle scattering scheme is realized when metallic mesh scatters tiny fraction of light on the MCP plate. In the present experiment we used geometry of direct illumination of MCP plate aiming detection of "ghost" bunches which may generate parasitically from the laser driven electron gun. Reduction of background conditions allowed us to detect light produced by electron bunches with extremely small charges, down to a few femtocoulmb. We measured for the first time structure of the dark current passing through the FLASH undulator. We have also been able to measure a high contrast of radiation produced by the photoinjector laser pulses switched on and off by a 1 MHz repetition rate Pockels cells.

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MOPOW017

Generation of GeV Photons from X-ray Free Electron Laser Oscillators

electron, laser, FEL, scattering

751

R. Hajima
JAEA, Ibaraki-ken, Japan
M. Fujiwara
RCNP, Osaka, Japan

We propose generation of narrow-bandwidth GeV photons, gamma-rays, via Compton scattering of hard X-ray photons in X-ray free-electron laser oscillators. The gamma-rays have a narrow-bandwidth spectrum with a sharp peak, ~0.1% (FWHM), due to the nature of Compton scattering in relativistic regime. Such gamma-rays will be a unique probe for studying hadron physics. We discuss features of the gamma-ray source, flux, spectrum, polarization, tunability and energy resolution.

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MOPOW029

The Soft X-ray Self-seeding System Design for SXFEL User Facility

undulator, FEL, electron, simulation

785

K.Q. Zhang, T. Liu, D. Wang
SINAP, Shanghai, People's Republic of China
Y. Feng
SLAC, Menlo Park, California, USA

X-ray free electron laser driven by SASE probes the evolution of the new generation light source in high brightness, transverse coherence. However, since SASE achieves lasing from random shotnoise, Poor longitudinal coherence and relative wide bandwidth of SASE FEL limit the operation of many type experiments. Self-seeding as a promising scheme produces longitudinal coherence and even narrower bandwidth radiation by a monochromatic seeding instead of external seeding. The self-seeding system design based on the grating monochromator is carried out for SXFEL user facility across the photon energy from 800-1200 eV. The grating monochromator with a resolution power of 〖10〗^-4 can provide a monochromatic seeding pulse to the seeding undulator. The layout design and simulations of the scheme are presented. It is showing that the self-seeding system for SXFEL user facility is able to improve SASE FEL longitudinal coherence significantly.

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MOPOW039

An Oscillator Configuration for Full Realization of Hard X-ray Free Electron Laser

electron, laser, optics, free-electron-laser

801

K.-J. Kim, T. Kolodziej, R.R. Lindberg, D. Shu, Yu. Shvyd'ko, S. Stoupin
ANL, Argonne, Ilinois, USA
V.D. Blank, S. Terentiev
TISNCM, Troitsk, Russia
Y. Ding, W.M. Fawley, J.B. Hastings, Z. Huang, J. Krzywinski, G. Marcus, T.J. Maxwell
SLAC, Menlo Park, California, USA
N.A. Medvedev
CFEL, Hamburg, Germany
W. Qin
PKU, Beijing, People's Republic of China
J. Zemella
DESY, Hamburg, Germany

Funding: Work at ANL supported under US Department of Energy contract DE-AC02-76SF00515 and at SLAC by the U.S. Department of Energy, Office of Science, under Contract No. DE-ACO2-O6CH11357
An X-ray free electron laser can be built in an oscillator (XFELO) configuration by employing an X-ray cavity with Bragg mirrors such as diamond*. An XFELO at the 5th harmonic frequency may be implemented at the LCLS II using its 4 GeV superconducting linac. The XFELO will provide stable, coherent, high-spectral-purity hard x-rays. In addition, portions of its output may be enhanced by the LCLS amplifier for stable pulses of ultrashort duration determined by the electron bunch length. Much progress has been made recently on the feasibility of an XFELO: Analytical and numerical methods have been developed to compute the performance of a harmonic XFELO. The energy spread requirement over a sufficient length of the bunch can be met by temporal shaping of the photo-cathode drive laser**. Experiments at the APS have shown that Be-compound refractive lenses are suitable for a low-loss focusing and that the synthetic diamond crystals can withstand the intense x-ray exposure, in accord with estimates based on molecular dynamics considerations***. A strain-free mounting of thin diamond crystal (< 100 microns) can be realized by shaping a thick diamond into a blind alley****.
* R. R. Lindberg et al., PRSTAB 1010701 (2011)
** W. Qin et al., this conference
*** N. Medvedev et al., Phys. Rev. B 88, 224304 (2013)
**** S. Terentyev, private communication

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MOPOW040

High Efficiency, High Brightness X-ray Free Electron Lasers via Fresh Bunch Self-Seeding

electron, undulator, simulation, extraction

805

C. Emma, C. Pellegrini
UCLA, Los Angeles, USA
M.W. Guetg, A.A. Lutman, A. Marinelli, C. Pellegrini, J. Wu
SLAC, Menlo Park, California, USA

High efficiency, terawatt peak power X-ray Free Electron Lasers are a promising tool for enabling single molecule imaging and nonlinear science using X-rays. Increasing the efficiency of XFELs while achieving good longitudinal coherence can be achieved via self-seeding and undulator tapering. The efficiency of self-seeded XFELs is limited by two factors: the ratio of seed power to beam energy spread and the ratio of seed power to shot noise power. We present a method to overcome these limitations by producing a strong X-ray seed and amplifying it with a small energy spread beam. This is achieved by selectively suppressing lasing for part of the bunch in the SASE section. In this manner we can saturate with the seeding electrons and amplify the strong seed with 'fresh' electrons downstream of the monochromator. Simulations of this scenario are presented for two systems, an optimal superconducting undulator design and the LCLS. In the case of the LCLS we examine how betatron oscillations leading to selective suppression are induced by using the transverse wakefield of a parallel plate dechirper. We also discuss extending the selective suppression scheme to chirped electron bunches.

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MOPOW044

Commissioning of the RadiaBeam / SLAC Dechirper

electron, wakefield, controls, alignment

809

M.W. Guetg, K.L.F. Bane, A. Brachmann, A.S. Fisher, Z. Huang, R.H. Iverson, P. Krejcik, A.A. Lutman, T.J. Maxwell, A. Novokhatski, G. Stupakov, J. Zemella, Z. Zhang
SLAC, Menlo Park, California, USA
M.A. Harrison, M. Ruelas
RadiaBeam Systems, Santa Monica, California, USA
J. Zemella
DESY, Hamburg, Germany
Z. Zhang
TUB, Beijing, People's Republic of China

We present results on the commissioning of the two-module RadiaBeam / SLAC dechirper system at LCLS. This is the first installation and measurement of a corrugated dechirper at high energy (4.4 - 13.3 GeV), short pulses (< 200 fs) and while observing its effect on an operational FEL. Both the transverse and longitudinal wakefields allow more flexible electron beam tailoring. We verify that, for a single module at a given gap, the strength of the longitudinal wake on axis and the dipole near the axis agree well with the theoretical values. Using direct longitudinal phase space mapping and X-ray FEL spectrum measurements we demonstrate the energy chirp control capabilities.

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MOPOW045

Measurement of Advanced Dispersion-based Beam-tilt Correction

lattice, electron, FEL, laser

813

M.W. Guetg, F.-J. Decker, Y. Ding, P. Emma, Z. Huang, T.J. Maxwell
SLAC, Menlo Park, California, USA

Funding: DOE contract \#DE-AC02-76SF00515
Free electron lasers in the X-ray regime require a good slice alignment along the electron bunch to achieve their best performance. A transverse beam slice shift reduces this alignment and spoils projected emittance and optics matching. Coherent synchrotron radiation, specifically for over-compression going through full compression, and transverse wakefields are major contributors to this. In the case of the large-bandwidth operation, with a strong energy chirp on the bunch, this misalignments furthermore reduce the spectral bandwidth of the FEL pulse. Well-defined manipulation of dispersion allows to compensate for this slice centroid shifts, therefore enhancing lasing power and in case of the large bandwidth mode, spectral bandwidth. This work shows the first application of this correction on an X-ray FEL resulting in increase in beam-power and bandwidth.

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TUZA02

Twin-bunch Two-colour FEL at LCLS

electron, laser, free-electron-laser, undulator

1032

A. Marinelli, R.N. Coffee, F.-J. Decker, Y. Ding, R.C. Field, S. Gilevich, Z. Huang, D. Kharakh, H. Loos, A.A. Lutman, T.J. Maxwell, J.L. Turner, S. Vetter
SLAC, Menlo Park, California, USA

Twin electron bunches have been the subject of much investigation at the Linac Coherent Light Source, due to their many applications to X-ray free-electron lasers (X-FEL). Twin bunches are trains of two electron bunches that are accelerated and compressed within the same accelerating RF period. At LCLS, these bunches are used in the downstream FEL undulator to generate two X-ray pulses of different energies for pump/probe applications or de novo phase determination of protein crystals. The spectral and temporal shaping of the two bunches requires exquisite control of the compression system to vary the main parameters of the system in a controlled way (peak current, temporal delay and energy separation). I will discuss recent experimental and theoretical results on this subject. In particular I will focus on the demonstration of mJ-level two-color X-ray pulses using twin bunches, as well as the temporal and spectral control of this new mode of operation. Finally, I will discuss our experience with user experiments as well as our future directions of investigation.

Slides TUZA02 [5.738 MB]

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TUOCB01

First Commissioning of the SuperKEKB Vacuum System

vacuum, electron, status, positron

1086

Y. Suetsugu, H. Hisamatsu, T. Ishibashi, K. Kanazawa, K. Shibata, M. Shirai, S. Terui
KEK, Ibaraki, Japan

The SuperKEKB, an electron-positron collider with asymmetric energies in KEK, has started the first commissioning with beams this year. One of major tasks in the commissioning is the beam scrubbing of new beam pipes in order to increase the beam lifetime and to decrease the background noise of the particle detector in the coming physics run. The temperatures and the vacuum pressures of new vacuum components, such as the bellows chambers, gate valves and the beam collimators, should be checked in this run. The decrease rate in the vacuum pressure are measured to estimate the vacuum scrubbing effect. Reported here will be the results obtained during the first commissioning and the present status of the vacuum system.

Slides TUOCB01 [2.526 MB]

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TUOCB02

Low Secondary Electron Yield of Laser Treated Surfaces of Copper, Aluminium and Stainless Steel

electron, laser, cavity, framework

1089

R. Valizadeh, P. Goudket, O.B. Malyshev, B.S. Sian, S. Wang
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
M.D. Cropper, S. Wang
Loughborough University, Loughborough, Leicestershire, United Kingdom
P. Goudket
Cockcroft Institute, Warrington, Cheshire, United Kingdom
B.S. Sian
UMAN, Manchester, United Kingdom
N. Sykes
Micronanics Laser Solution Center, Didcot, United Kingdom

Funding: STFC
Reduction of SEY was achieved by surface engineering through laser ablation with a laser operating at • = 355 nm. It was shown that the SEY can be reduced to near or below 1 on copper, aluminium and 316LN stainless steel. The laser treated surfaces show an increased surface resistance, with a wide variation in resistance found de-pending on the exact treatment details. However, a treated copper surface with similar surface resistance to aluminium was produced.

Slides TUOCB02 [94.339 MB]

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TUPMB050

Development of Multi-channel Line for the NSRRC Cryogenic System

cryogenics, vacuum, radiation, synchrotron

1212

P.S.D. Chuang, S.-H. Chang, W.-S. Chiou, F. Z. Hsiao, H.C. Li, W.R. Liao, T.F. Lin, H.H. Tsai
NSRRC, Hsinchu, Taiwan

For the past few years, the technology of X-ray photon source is getting more and more advanced, more and more countries are now striving to build the biggest synchrotron facility to meet its' need. In Taiwan, the construction of an electron accelerator with the energy of up to 3.5 GeV is constructed to fulfill the strong demands for an X-ray photon source with high brilliance and flux. Thus, to let the TPS be under stable operation, the cryogenic system is therefore very important. The refrigerant of the TPS Cryogenic System is Liquid Helium, to maintain liquid helium in its state, the temperature has to be maintained under 4.5K, however to let liquid helium turn into gas helium, only 20 W is needed. Therefore, the Multi-Channel Line is developed in our system to prevent heat from conduction in and letting liquid helium vaporize. Several mechanical parts have been designed to reduce heat loss and meet its needs, for example the Spacer. The paper presents a design methodology of long multi-channel helium cryogenic transfer lines. It describes some aspects thermo-mechanical calculation, supporting structure and contraction protection.

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TUPOW041

Optimization Studies for the Beam Dynamic in the RF Linac of the ELI-NP Gamma Beam System

electron, laser, linac, emittance

1850

C. Vaccarezza, D. Alesini, M. Bellaveglia, M.E. Biagini, G. Di Pirro, A. Gallo, A. Ghigo, S. Guiducci, A. Vannozzi, A. Variola
INFN/LNF, Frascati (Roma), Italy
A. Bacci, I. Drebot, D.T. Palmer, A.R. Rossi, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
G. Campogiani
Rome University La Sapienza, Roma, Italy
A. Giribono, A. Mostacci, L. Palumbo
University of Rome La Sapienza, Rome, Italy
V. Petrillo
Universita' degli Studi di Milano & INFN, Milano, Italy
L. Sabbatini
Consorzio Laboratorio Nicola Cabibbo, Frascati, Italy

The ELI-NP GBS is an high spectral density and monochromatic gamma ray source based upon the inverse Compton scattering effect now under construction in Magurele. Its relevant specifications are brilliance higher than 10²¹, 0.5% monochromaticity and a 0.2-19.5 MeV energy tunability. Strong requirements are set for the electron beam dynamic: the control of both the transverse normalized emittance and the energy spread to optimize the spectral density and guarantee the mono chromaticity of the emitted radiation. On this basis the RF Linac optimization has been performed for the designed energy range; a sensitivity analysis of the machine to possible jitters, errors and so on has been also performed, the simulations results hare here presented.

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TUPOW042

Expected Gamma Spectra at ELI-NP-GBS

laser, polarization, electron, collimation

1854

I. Drebot, C. Curatolo
Universita' degli Studi di Milano e INFN, Milano, Italy
A. Bacci, A.R. Rossi, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
A. Giribono
University of Rome "La Sapienza", Rome, Italy
V. Petrillo
Universita' degli Studi di Milano & INFN, Milano, Italy
C. Vaccarezza, A. Variola
INFN/LNF, Frascati (Roma), Italy

The ELI-NP-GBS is an advanced source of up to 20 MeV Gamma Rays based on Compton back-scattering. We present the investigation of the production of the ELI-NP gamma photon beam generated by Compton back-scattering between the electron bunch accelerated in the linac and the laser pulse. At the interaction point (IP), the Compton backscattering properties, as spectral flux, brilliance and polarization are evaluated by the Klein-Nishina cross section. The gamma beam produced has energy ranging from 0.2 to 19.5 MeV and bandwidth of 0.5%. In order to define the optimal layout and evaluate the performances of the collimation and detection systems, a detailed Monte Carlo simulation activity has been carried out taking into account possible jitters and errors.

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TUPOW043

Electron Beam Dynamics Studies for ELI-NP GBS Linac

electron, linac, operation, beam-loading

1857

A. Giribono, F. Cardelli, L. Palumbo, L. Piersanti
University of Rome La Sapienza, Rome, Italy
D. Alesini, A. Gallo, C. Vaccarezza, A. Vannozzi
INFN/LNF, Frascati (Roma), Italy
A. Bacci, C. Curatolo, I. Drebot, V. Petrillo, A.R. Rossi, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
G. Campogiani
Rome University La Sapienza, Roma, Italy
F. Cardelli, L. Piersanti
INFN-Roma1, Rome, Italy
L. Palumbo
INFN-Roma, Roma, Italy

The ELI-NP Gamma Beam System is an advanced gamma ray source based on the Compton back-scattering effect with unprecedented specifications of brilliance ( >10²¹), monochromaticity (0.5%) and energy tunability (0.2 - 19.5 MeV), presently under construction in Magurele-Bucharest (RO). Here the head-on collision is foreseen between an intense high power laser beam and a high brightness high quality electron beam with a maximum kinetic energy of 740 MeV. The electron beam dynamics analysis and control for the ELI-NP GBS Linac in the single and multi bunch mode have been investigated and are here illustrated.

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TUPOW046

Development and Upgrade Plan of an X-ray Source Based on Laser Compton Scattering in Laser Undulator Compact X-ray Source(LUCX)

laser, electron, detector, cavity

1867

M.K. Fukuda, S. Araki, Y. Honda, N. Terunuma, J. Urakawa
KEK, Ibaraki, Japan
M. Kageyama, M. Kuribayashi
Rigaku Corporation, XG & Core Technology, Tokyo, Japan
A. Momose, M.P. Olbinado, Y. Wu
Tohoku University, Institute of Multidisciplinary Research for Advanced Materials, Sendai, Japan
K. Sakaue
Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
M. Washio
RISE, Tokyo, Japan

Funding: This work was supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
We have been developing a compact X-ray source based on Laser Compton scattering(LCS) at Laser Undulator Compact X-ray source(LUCX) accelerator in KEK. Our aim is to obtain a clear X-ray image in a shorter period of times and the target number of X-ray is 1.7x10⁷ photons/pulse with 10% bandwidth. In the accelerator, an electron beam with the energy of 18-24 MeV is generated by an S-band normal conducting accelerator. The beam is collided with a laser pulse stacked in a 4-mirror planar optical cavity and then 6-10 keV X-rays are generated by LCS. Presently, the generation of X-rays with the number of 3x10⁶ photons/pulse at the collision point has been achieved. X-ray imaging test such as refraction contrast images and phase contrast imaging with Talbot interferometer has also started. To increase the intensity of X-rays, we are continuing the tuning of the electron beam and the optical cavity because the exposure time of X-ray imaging is too long now. We are also planning to increase the beam energy by appending the accelerating tube. In this conference, the recent results and upgrade plan in LUCX will be reported.

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TUPOW049

Expected Results From Channeling Radiation Experiments at Fast

detector, electron, background, emittance

1873

T. Sen, D.R. Broemmelsiek, D.R. Edstrom
Fermilab, Batavia, Illinois, USA
J. Hyun
Sokendai, Ibaraki, Japan
D. Mihalcea, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
W.D. Rush
KU, Lawrence, Kansas, USA

Funding: Fermilab is operated by Fermi Research Alliance LLC under DOE contract No. DE-AC02CH11359
The photoinjector at the new Fermilab FAST facility will accelerate electron beams to about 50 GeV. After initial beam commissioning, channeling radiation experiments to generate hard X-rays will be performed. In the initial stage, low bunch charge beams will be used to keep the photon count rate low and avoid pile up in the detector. We report here on the optics solutions, the expected channaling spectrum including background from bremmstrahlung and the use of a Compton scatterer for higher bunch charge operation.

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TUPOW050

Parametric X-rays at FAST

brilliance, electron, detector, scattering

1877

T. Sen
Fermilab, Batavia, Illinois, USA

Funding: Fermilab is operated by Fermi Research Alliance LLC under DOE contract No. DE-AC02CH11359
We discuss the generation of parametric X-rays (PXR) in the photoinjector at the new FAST facility at Fermilab. Detailed calculations of the intensity spectrum, energy and angular widths and spectral brilliance with a diamond crystal are presented. We also report on expected results with PXR generated while the beam is channeling. The low emittance electron beam makes this facility a promising source for creating brilliant X-rays.

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TUPOW051

Optimization of Electron Beam and Laser Pulse Alignment and Focusing at Interaction Point for a Compact FEL Based Inverse-Compton Scattering X-Ray Source

electron, laser, FEL, undulator

1881

P. Niknejadi, J. Madey
University of Hawaii, Honolulu,, USA

Funding: This work was funded under the Department of Homeland Security Grant No. 2010-DN-077-ARI045.
In July 2015, the first beam of 10 keV X-rays from our FEL based inverse-Compton scattering X-ray source was detected.* In this setup, 3 micron laser pulses at 2.856 GHz repetition rate from a free electron laser are collided head-on with 40 MeV electron bunches driving the laser. To attain our objective the ebeam was required to have 1) a tight focus at the X-ray interaction point, 2) vertical and horizontal envelopes matched to the downstream undulator, 3) minimized transverse dimensions for low ionizing radiation. Optimization of these quantities required information on the evolution of the beam profiles between the beam spot images on the available insertable screens, leading to the need for a simulator to accurately trace the beam profiles through the system. A simulator was developed and used to optimize the system Twiss parameters by comparing the effectiveness of the beam profiles computed by fitting the profiles to the observed beam spot images along the beamline for different cathode positions. This method proved to be considerably more flexible and effective than the more traditional quadrupole scan technique. Summery of the designed system and results are provided.
* John M. J. Madey, ARI final report, December 2015.

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TUPOW052

LLNL Laser-Compton X-ray Characterization

laser, electron, simulation, background

1885

Y. Hwang, T. Tajima
UCI, Irvine, California, USA
G.G. Anderson, C.P.J. Barty, D.J. Gibson, R.A. Marsh
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
Laser-Compton X-rays have been produced at LLNL, and results agree very well with modeling predictions. An X-ray CCD camera and image plates were calibrated and used to characterize the 30 keV X-ray beam. A resolution test pattern was imaged to measure the source size. K-edge absorption images using thin foils confirm the narrow bandwidth of the source and offer electron beam diagnostics.

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TUPOW055

Coronagraph Measurements on the Australian Synchrotron Storage Ring Optical Diagnostic Beamline

synchrotron, background, extraction, diagnostics

1895

M.J. Boland, Y.E. Tan
SLSA, Clayton, Australia
T.M. Mitsuhashi
KEK, Ibaraki, Japan

A coronagraph was constructed on the Optical Diagnostic Beamline at the Australian Synchrotron to observe the tails of the stored beam and the injected beam on the first few turns. Some results are presented with special emphasis on the limitation of the dynamic range due to the quality of the synchrotron light extraction mirror.

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TUPOY018

FLUKA Simulations for Radiation Protection at 3 Different Facilities

neutron, proton, ion, radiation

1940

R. Rata, S.C. Lee
IIAA, Huddersfield, United Kingdom
R.J. Barlow
University of Huddersfield, Huddersfield, United Kingdom

FLUKA Monte Carlo Code is a transport code widely used in radiation protection studies. The code was developed in 1962 by Johannes Ranft and the name stands for FLUktuierende Kaskade (Fluctuating Cascade). The code was developede for high-energy physics and it can track 60 different particles from 1keV to thousands of TeV. It can be applied to accelerator design, shielding design, dosimetry, space radiation and hadron therapy. For particle therapy, FLUKA uses various physical models, all implemented in the PEANUT (Pre-Equilibrium Approach to Nuclear Thermalization) framework. The investigation was made for three different facilities : the Clatterbridge Cancer Centre, the Christie Hospital and the OpenMeD facility at CERN. We calculated the secondary dose distributed to the patient, in case of Clatterbridge Cancer Centre, and to the workers in case of the Christie Hospital and OpenMeD, and to investigate whether the shielding methods meet the existing radiation protection requirements and that the doses to the staff are kept As Low As Reasonably Achievable (ALARA).

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TUPOY046

Study on NRF-CT Imaging by Laser Compton Backscattering Gamma-rays in UVSOR

target, detector, laser, resonance

2007

H. Ohgaki, I. Daito, T. Kii, H. Zen
Kyoto University, Kyoto, Japan
T. Hayakawa, T. Shizuma
JAEA, Ibaraki-ken, Japan
M. Katoh, J. Yamazaki
UVSOR, Okazaki, Japan
Y. Taira, H. Toyokawa
AIST, Tsukuba, Japan

Funding: This work was supported by JSPS KAKENHI Grant Number 26289363, 24340060 and the Joint Studies Program (2014) of the Institute for Molecular Science.
Monochromatic gamma-ray beam in MeV energy region is suitable for non-destructive inspection of high density and massive objects because of its high penetrability. A specific nuclide can be detected by the process of Nuclear Resonance Fluorescence (NRF). A non-destructive inspection of Special Nuclear Materials hidden in a container cargo using NRF is proposed by Bertozzi*. Non-destructive detection of Pu inside of a spent nuclear fuel rod is also proposed for management of radioactive wastes, nuclear material accounting and safeguards**. We have developed 2D NRF imaging by using quasi-monochromatic gamma-ray beam in MeV energy region generated by Laser Compton Backscattering (LCS) method*** and proposed to develop an NRF-CT image in the ELI-NP where a high intensity LCS beam can be available in near future. To demonstrate and finalize the measurement system of the NRF-CT imaging by using LCS gamma-ray beam, we have started a study on NRF-CT imaging at the new LCS beamline in UVSOR. The LCS beamline can generate 5.4 MeV LCS gamma-rays with a flux of 1×10⁷ photons/s. We have measured the 5.291 MeV NRF gamma-rays from a lead target in this beamline and tried to take a NRF-CT image.
* W. Bertozzi et al., Nucl. Inst. Meth. B241, 820-825 (2005).
** B. Ludewigt et al., Proc. of 2010 ANS meeting (2010).
*** H. Toyokawa et al., JJAP, 50, 100209 (2011).

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WEOCA03

Simulating Proton Synchrotron Radiation in the Arcs of the LHC, HL-LHC and FCC-hh

optics, simulation, radiation, electron

2073

G. Guillermo Cantón, F. Zimmermann
CERN, Geneva, Switzerland
D. Sagan
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

At high proton-beam energies, beam-induced synchrotron radiation is an important source of heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can give rise to an electron cloud. We use the Synrad3D code developed at Cornell to simulate the photon distributions in the arcs of the LHC, HL-LHC, and FCC-hh. Specifically, for the LHC we study the effect of the "sawtooth" chamber, for the HL-LHC the consequences of the ATS optics with large beta beating in the arcs, and for the FCC-hh the effect of a novel beam-screen design, with a long slit surrounded by a "folded" ante-chamber.

Slides WEOCA03 [0.329 MB]

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WEOAB03

Photoemission Properties of LaB6 and CeB6 Under Various Temperature and Incident Photon Energy Conditions

cathode, laser, electron, vacuum

2088

K. Morita, T. Katsurayama, T. Kii, K. Masuda, T. Murata, K. Nagasaki, T. Nogi, H. Ohgaki, S. Suphakul, K. Torgasin, H. Yamashita, H. Zen
Kyoto University, Kyoto, Japan

Recently, thermionic cathode materials such as LaB6, Ir5Ce and dispenser cathodes have been also used as photocathode since they have low work function, reasonably high quantum efficiency, and long lifetime*,**. However, the effect of cathode temperature and laser wavelength on quantum efficiency is known only for limited conditions. Although it is expected to be able to lengthen the required wavelength of photocathode drive laser by heating cathodes, laser with photon energy under the work function has not been tested. Revealing them enables us to design the cost minimum accelerators. In this research, photoemission properties of LaB6 and CeB6 with various excitation photon energies will be investigated under various temperatures of the materials. Those materials have similar work function, but CeB6 have one order of magnitude smaller Richardson constant than LaB6***. By comparing photoemission properties of these materials, impact of Richardson constant on the photoemission properties will be investigated.
* S. Thorin et al. Proc of FEL2009, 310
** D. Satoh et al. Proc of IPAC2014, 679
*** J.M. Lafferty, J. Appl. Phys. 22, (1951), 299

Slides WEOAB03 [0.996 MB]

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WEPMB019

Magnetic Fields in Bulk, Film, and Multilayer Superconductors in Front of a Multi-turn Coil

experiment

2164

T. Kubo
KEK, Ibaraki, Japan

Funding: JSPS Young Scientists(B) #26800157, JSPS Challenging Exploratory Research #26600142, MEXT Photon and Quantum Basic Research Coordinated Development Program
The magnetic field distribution formulae in a bulk superconductor, a superconducting film, and an SIS multilayer structure in front of a multi-turn coil are derived, which may be useful for a detailed analysis in a vortex field measurement by using the third harmonic method.
* See for example the invited oral presentation by T. Kubo, "Theory of multilayer coating for proof-of-concept experiments", at SRF2015
** C.Z.Antoine et al., Appl. Phys. Lett. 102, 102603 (2013)

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WEPMB025

Fabrication of Superconducting Spoke Cavity for Laser Compton Scattered Photon Sources

cavity, laser, simulation, linac

2177

M. Sawamura, R. Hajima
QST, Tokai, Japan
H. Hokonohara, Y. Iwashita, H. Tongu
Kyoto ICR, Uji, Kyoto, Japan
T. Kubo, T. Saeki
KEK, Ibaraki, Japan

Funding: The work is supported by Photon and Quantum Basic Research Coordinated Development Program from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
We have launched a 5-year research program to develop superconducting spoke cavity for laser Compton scattered (LCS) photon sources. For realizing a wide use of LCS X-ray and γ-ray sources in academic and industrial applications, we adopt the super-conducting spoke cavity to electron beam drivers. The spoke cavity has advantages such as relative compactness in comparison with an elliptical cavity of the same frequency, robustness with respect to manufacturing inaccuracy due to its strong cell-to-cell coupling, the better packing in a linac to install couplers on outer conductor. On the other hand the spoke cavity has disadvantage of more complicated structure than an elliptical cavity. Though our proposal design for the photon source consists of the 325 MHz spoke cavities in 4K operation, we have begun to fabricate the half scale model of 650 MHz spoke cavity in order to accumulate our cavity production experience by effective utilization of our limited resources. In this paper, we present our fabrication status.

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WEPMR040

HOM Absorber Study by Photon Diffraction Model

HOM, cavity, damping, SRF

2360

C. Xu, I. Ben-Zvi, V. Ptitsyn, P. Takas, W. Xu
BNL, Upton, Long Island, New York, USA
I. Petrushina
SUNY SB, Stony Brook, New York, USA
B. P. Xiao
SBU, Stony Brook, New York, USA

Photon diffraction model (PDM) is one of the most promising candidates to study High Order Mode (HOM) power absorption on absorbing materials for high current SRF cavities. Because at very high frequency (>10GHz), the wavelengths of HOMs are much smaller compared with accelerators dimension, the phase of those HOM will be negligible. Meanwhile, Finite Element Method (FEM) cannot lend a high resolution on evaluation the HOM field patterns due to limited meshing capability. This PDM model utilizes Monte Carlo simulation to trace the ray diffusive reflection in a cavity. This method can directly estimate the power absorption on the cavity and absorber wall. This method will help design the HOM damper setup for eRHIC HOM damper. In this report, we evaluate HOM absorption on the cavity wall with different absorber setup and give a possible solution for power damping scheme for high frequency HOMs.

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WEPMR047

Overall Design of Magnet Girder System for Heps-Tf

alignment, controls, emittance, storage-ring

2383

H. Wang, L. Gong, C.H. Li, S. Li, H. Qu, Z. Wang, L. Wu
IHEP, Beijing, People's Republic of China

HEPS-TF is the test facility of HEPS (High Energy Pho-ton Source) of China. The magnet girders are used for supporting and positioning of the magnets. As the beam emittance is very low, the girder must has high adjusting precision and high stability. Besides, the girder should also be beam-based aligned. For these issues, two girder systems are designed. Both of them use cam mover mech-anisms for precision adjustment. One has six cam mover mechanisms and another has eight. The design aim of the alignment accuracy between girders is within 50 μm, and the adjusting resolution is within 3μm. The design aim of the natural frequency is above 30 Hz. This paper will discuss the scheme selection and structural design of the girder systems.

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WEPMW010

Effect of Beamstrahlung on Bunch Length and Emittance in Future Circular e⁺e⁻ Colliders

radiation, collider, emittance, synchrotron

2438

M.A. Valdivia García, F. Zimmermann
CERN, Geneva, Switzerland

In future circular e⁺e⁻ colliders, beamstrahlung may limit the beam lifetime at high energies, and increase the energy spread and bunch length at low energies. If the dispersion or slop of the dispersion is not zero at the collision point, beamstrahlung will also affect the transverse emittance. In this paper, we first examine the beamstrahlung properties, and show that for the proposed FCC-ee, the radiation is fairly well modelled by the classical formulae describing synchrotron radiation in bending magnets. We then derive a set of equations describing the equilibrium beam parameters in the presence of a nonzero dispersion at the collision point. An example case from FCC-ee will serve as an illustration.

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WEPMY040

Fabrication of Two Dimensional Nano-Scale Photocathode Arrays in Transparent Conductor for High Coherence Beam Generation

electron, laser, cathode, simulation

2645

T. Shibuya
TIT, Tokyo, Japan
N. Hayashizaki
RLNR, Tokyo, Japan
M. Yoshida
KEK, Ibaraki, Japan

Electron beam quality for particle source of diffractometer is mainly characterized by transverse and longitudinal coherent length, beam current density and so on. In order to improve a transverse coherent length, it is practically essential to minimize electrons emission area size as small as possible. However, the size of photoemission area is limited by focused laser beam size on the surface of cathode, and the scale is several microns. Aim to get definite overlap between the focused laser and emitters for effective irradiation, as well as to realize generation of nano-scale size electron beam, nano-scale photocathode arrays in transparent conductor are essential. Therefore, I propose to fabricate the nano-scale emission area in replace of limiting the focused laser size on the photocathode for achieving high coherence beam. The fabrication process of this novel nano-scale emitter configuration and its fundamental properties are presented in this paper.

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WEPOR024

HPGe Detector Application on Monitoring Environmental Samples around the Accelerator

detector, simulation, software, monitoring

2725

Y.D. Ding, Z.J. Ma, Q.B. Wang, M.Y. Yan, Q.J. Zhang
IHEP, Bejing, People's Republic of China

Massive experimental works are aimed to clarify the structure of detector including CT with X ray machine, determining the thickness of dead layer with collimating radioactive source and ect. Measuring structure and size of the detector by X-ray computed tomography, measur-ing the dead layer thickness of detector's front surface and side surface though collimated point source method, scanning the dead layer distribution of the entire detec-tor. A finite element analysis software name CST is used to simulate electric field distribution of the HPGe detec-tor. Calibrating the efficiency of HPGe detector by means of point source and soil standard matter, A Monte Carlo software called MCNP is used to simulate detector effi-ciency preliminarily according to the structure parame-ters of the factory, optimizing and verifying simulated results on the basis of measured results. At last, the com-parison of the simulated and the experimental data showed very good agreement.

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WEPOW011

BESSY II Supports an Extensive Suite of Timing Experiments

experiment, synchrotron, operation, timing

2840

R. Müller, T. Birke, F. Falkenstern, K. Holldack, P. Kuske, A. Schälicke, D. Schüler
HZB, Berlin, Germany
H.G. Glass, R. Ovsyannikov
BESSY GmbH, Berlin, Germany

The synchrotron light source facility BESSY II has put top-up and a fast orbit feedback (FOFB) into operation in 2013. Both operational improvements have matured and turned out to be especially beneficial for the advanced timing opportunities supported at BESSY. In combination with very tight injection efficiency requirements a thorough understanding of top-up injections under all operational conditions has been developed. Consequently arbitrary bunch currents can be dialed in and maintained on demand. In standard mode, a very pure camshaft bunch is available both in general for laser pump/X-ray probe and for pseudo single bunch experiments at the MHz chopper beamline. 3 constant high current bunches support the FEMTOSPEX slicing facility. An additional bunch can be resonantly excited and pulse picked via custom orbit bumps at 3 different undulator beamlines (PPRE). Due to the FOFB the classical timing modes "single bunch" and "low alpha" feature an attractive pointing stability.

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WEPOW021

The Low Emittance Reconstruction of the Arc Section of the Photon Factory

emittance, dynamic-aperture, sextupole, lattice

2874

K. Harada, Y. Kobayashi, N. Nakamura, K. Oide, H. Sakai, S. Sakanaka
KEK, Ibaraki, Japan

The present horizontal emittance of the Photon Factory (PF) ring is about 35.4 nmrad. By the reconstruction of the normal cells at the arc section, the emittance can be reduced to about 8 nmrad. The double number of the combined function short bending magnets are adopted and one present normal cell become two new normal cells. Although the lattice of the straight sections are not changed, the optics are optimized to reduce the non-linear effects of the sextupoles of the arc sections. By keeping the tune advance of the straight section as 3 for the horizontal direction and 2.5 for the vertical, the dynamic aperture as large as that of the present ring can be achieved with the magnetic errors. The difference of the optics of the straight sections are so little that the beam injection and the operation of the in-vacuum short-gap undulators can be maintained. The hardware design will be began as the next step for the realization of the plan. In this proceedings, the design, optimization and simulation results for the low emittance lattice are shown.

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WEPOW039

Preliminary Beam Loss Study of TPS during Beam Commissioning

injection, radiation, scattering, EPICS

2926

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

Taiwan photon source (TPS) is a 3rd generation and 3 GeV synchrotron light source in NSRRC. Several types of beam loss monitors (BLMs) such as RadFETs and PIN-diode BLMs are installed in the storage ring to understand the beam loss distribution and mechanism during the injection, decay mode, top-up operation and beam trip. Several RadFETs are also installed around the inserting devices to study the beam loss near the linear scalar. The preliminary beam loss study using RadFETs are PIN-diode BLMs in the storage will be summarized in this report.

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WEPOW042

Properties of Synchrotron Radiation from Segmented Undulators based on a Wigner Distribution Function

undulator, electron, brilliance, radiation

2933

H.W. Luo, C.H. Lee
NTHU, Hsinchu, Taiwan
T.Y. Chung, C.-S. Hwang
NSRRC, Hsinchu, Taiwan

Three long straight sections with a double mini-βy lattice were designed in Taiwan Photon Source. For the purpose to understand whether the brilliance can be enhanced or not when two collinear undulators were installed in the double mini-βy. Therefore, the Wigner distribution function (WDF) is developed to calculate the brilliance in the double mini-βy lattice that is a natural way to describe a synchrotron radiation source. Herein, the brilliance is thereby calculable without a Gaussian approximation used in a conventional manner. Some important optical properties such as the degree of coherence can be directly calculated with this method. We use it as an example to investigate the properties of radiation from a segmented undulator.

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WEPOW045

Concepts for a Low Emittance-High Capacity Storage Ring for the Diamond Light Source

lattice, emittance, wiggler, dipole

2943

R. Bartolini, G. Cinque, G. Evans, K. Sawhney, J. Zegenhagen
DLS, Oxfordshire, United Kingdom

The Diamond Light Source is investigating several paths for a possible machine upgrade to Diamond II. The exercise is driven by by a joint assessment of the science capabilities opened by a very low emittance ring and the machine design that will underpin them. The consultation is made on a beamline-by-beamline basis and has highlighted a significant preference for lattices that combine both a low emittance and large capacity for IDs.

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THPMB042

Residual Orbit Correction Studies for the FCC-hh

quadrupole, dipole, alignment, hadron

3332

D. Boutin, B. Dalena
CEA/IRFU, Gif-sur-Yvette, France
A. Chancé, J. Payet
CEA/DSM/IRFU, France
B.J. Holzer, R. Martin, D. Schulte
CERN, Geneva, Switzerland

The FCC-hh (Future Hadron-Hadron Circular Collider) is one of the three options considered for the next genera-tion accelerator in high-energy physics as recommended by the European Strategy Group [*]. Preliminary studies have started to estimate the design parameters of FCC-hh. One of these studies is the calculation of the residual orbit in the arcs of the collider. This is very important for the evaluation of the alignment tolerances of the quadru-poles used in the arcs, the dimensioning of the correctors and of the beam screen. Moreover it has an impact on the dynamic aperture of the ring and the field tolerances of the arc multipoles. To perform the simulations, the beam transport code MADX has been used. Systematic studies of the residual orbit and of the correctors' strength de-pendence on the magnets misalignment or field errors are presented and discussed.
[*] A. Ball et al., EDMS-0134202.

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THPMR017

Resonance Island Experiments at BESSY II for User Applications

undulator, operation, resonance, experiment

3427

P. Goslawski, J. Feikes, K. Holldack, A. Jankowiak, M. Ries, M. Ruprecht, A. Schälicke, G. Wüstefeld
HZB, Berlin, Germany
R. Ovsyannikov
BESSY GmbH, Berlin, Germany

Beam storage close to a tune resonance (Qx = 1/3, 1/4) can generate resonance island buckets in the x,x' phase space providing a second stable island orbit winding around the standard orbit. Experiments with such an operation mode have been conducted at BESSY II and the Metrology Light Source (MLS)*,**. The two orbits are well separated, with good life time and stability. Such operation mode will offer additional operation flexibility and allows users to choose their radiation source point from one or the other orbit. It has the potential to fulfill simultaneously conflicting user demands, e.g., high vs. low beam current and single or few bunch filling vs. multibunch filling. We discuss the required beam optics setup and present successful measurements taken at photon beamlines at BESSY II.
* P. Goslawski et al., "Bunch Separation by Transverse Resonance Island Buckets", ESLS XXIII Workshop, 2015, Villigen, Switzerland.
** M. Ries et al., Proc. IPAC 2015, Richmond, USA, MOPWA021.

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THPMW017

Phase Shifter Power Supply Design

controls, simulation, electron, power-supply

3576

Y.T. Li, K.-B. Liu, B.S. Wang, Y.S. Wong
NSRRC, Hsinchu, Taiwan

Taiwan Photon Source is an interdisciplinary project. The phase-shift magnet is used to connect the radiation phase between two EPU48s. The power supply for this phase-shift magnet is a key element to determine the phase shift quality. In this report, the theory of the designed circuit is firstly introduced, and then a comparison simulation result and actual measurement is summarized to prove the correctness of theoretical analysis and circuit design.

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THPMY001

Design and R&D for the SPring-8 Upgrade Storage Ring Vacuum System

vacuum, storage-ring, laser, radiation

3651

M. Oishi, T. Bizen, H. Ohkuma, M. Shoji, S. Takahashi, K. Tamura, Y. Taniuchi
JASRI/SPring-8, Hyogo-ken, Japan

Conceptual design report for the SPring-8 upgrade project (SPring-8-II) was published in November of 2014. Vacuum system for the targeted storage ring should handle some fateful boundary conditions, such as miniaturization of vacuum chamber and increase in number of photon absorbers resulting from the multi-bend achromat configuration. Furthermore, reuse of the existing tunnel brings the severe packing factor issue of vacuum components and the time constraints issue of one-year blackout. Considering the above circumstances, a concept of 12-m long vacuum chamber with welded integral structure was proposed to omit in-situ baking. The 12-m long chamber will be evacuated to ultra-high vacuum by ex-situ baking followed by NEG activation, and moved to the tunnel with special thin gate valves at both ends. Recently, the chamber material has been changed from aluminum alloy to stainless steel (SS) from the viewpoints of elimination of aluminum-SS transition space, beam vibration suppression, and superior outgassing property. Trial production of SS chamber is proceeding to establish appropriate manufacturing processes, while focusing on the accuracy of dimension and magnetic permeability.

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THPMY018

Benchmarking and Calibration of Monte Carlo Vacuum Simulations with SynRad and MolFlow+

vacuum, storage-ring, experiment, scattering

3695

J.A. Carter
ANL, Argonne, Ilinois, USA

The APS-Upgrade project is using SynRad and MolFlow+ to evaluate the vacuum system design for the future 6 GeV, 200 mA APS-Upgrade storage ring. The goal of this work is to explore PSD outgassing predictions from the two programs in order to build confidence in pressure calculations for the APS-U storage ring vacuum system. A study is performed on calibrating PSD measurements for aluminum vacuum chambers and then applying them to APS-U vacuum system calculations. The study reveals that a PSD measurement may not reveal a single unique behavior for a vacuum material and that multiple sources should be considered for vacuum calculations.

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THPOR020

Status of VEPP-4M Collider

experiment, injection, storage-ring, detector

3818

E.B. Levichev, O.I. Meshkov, P.A. Piminov, A.N. Zhuravlev
BINP SB RAS, Novosibirsk, Russia

At present the VEPP-4 storage ring facility provides varied experimental programs including HEP, nuclear physics, synchrotron radiation, polarized electron/positron beam research, etc. Until now, the studies were mainly performed at the beam energy below 2 GeV but a strong interest of experimentalists encourages us to increase the beam energy up to 5 GeV. Reliable and high-performance operation at high energy is a challenge for the machine. Here we discuss the recent experimental results at the low energy, and prospects and constraints of the energy ramp.

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THPOR030

Commissioning and First Performance Studies of a Single Vertical Beam Halo Collimation System at ATF2

background, collimation, simulation, wakefield

3844

N. Fuster-Martínez, A. Faus-Golfe
IFIC, Valencia, Spain
P. Bambade, A. Faus-Golfe, S. Wallon, R.J. Yang
LAL, Orsay, France
K. Kubo, T. Okugi, T. Tauchi, N. Terunuma
KEK, Ibaraki, Japan
I. Podadera, F. Toral
CIEMAT, Madrid, Spain
T. Tauchi, N. Terunuma
Sokendai, Ibaraki, Japan

A single vertical beam halo collimation system has been installed in the ATF2 beamline to reduce the background that could limit the precision of the diagnostics located in the post-IP beamline. On this paper the commissioning and first performance studies of a single vertical beam halo collimation system are reported. Furthermore realistic efficiency studies have been done using the simulation code BDSIM and compared with the first experimental tests.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR030

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THPOW004

Pulse Response Measurements of NEA Photocathodes at Different Laser Wavelengths

laser, electron, cavity, cathode

3931

M.A. Dehn, K. Aulenbacher, V. Bechthold
IKP, Mainz, Germany

For high average electron beam currents the length of the electron bunches must match the acceptance of the accelerator. At Johannes Gutenberg-University Mainz we are able to measure the longitudinal pulse response of NEA photocathodes (GaAs) under photo excitation of different wavelengths. A time resolution of < 2 ps at a beam energy of 100 keV is achieved, furthermore, a high dynamic range allows to investigate long ranging tails of the response (longitudinal halo). This serves to identify the best possible operation mode for high current photo sources.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW004

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THPOW016

Transverse Energy Spread Measurements from GaAs Photocathodes at Variable Wavelengths

electron, cathode, detector, laser

3964

T.C.Q. Noakes, R. Beech, L.B. Jones, B.L. Militsyn
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
H.E. Scheibler, A.S. Terekhov
ISP, Novosibirsk, Russia

The transverse energy spread spectrometer (TESS) is an instrument specially developed at Daresbury Laboratory to measure the intrinsic transverse and longitudinal energy distributions from photocathode materials. Early work on the instrument has focussed on its use for the characterisation of GaAs photocathodes such as those commonly used in DC photoinjectors. More recently work has been conducted to extend the range of materials which can be evaluated using this apparatus, in particular by incorporating a monochromated white light source. New results are presented using the white light source to measure the energy spread of a GaAs photocathode across a range of different wavelengths to evaluate how this changes with excess energy.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW016

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THPOW025

Photocathode Growth and Characterization Advances at Cornell University

electron, emittance, cathode, gun

3990

L. Cultrera, A.C. Bartnik, I.V. Bazarov, B.M. Dunham, C.M. Gulliford, H. Lee, R.A. Lipton, T.P. Moore
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA

Alkali-antimonides based photocathodes have demonstrated outstanding performance in high brightness electron beam production suitable for a wide range of applications such as FELs, ERLs and UED and for use in photomultiplier devices with picosecond resolution aimed at photon counting application in medicine and High Energy Physics. The photocathode laboratory at Cornell University is dedicated to studying the growth procedures and characterizing the properties in a wide range of photocathodes materials. Different experimental arrangements and alkali metal sources have been successfully explored to date to synthesize photosensitive materials. Recent work on commissioning a new growth chamber equipped with effusion cells loaded with pure metal allowing uniform deposition over large area substrates resulted on successful growth of photocathodes with extended sensitivity in the IR part of the spectrum and high efficiency alkali antimonides containing Rb metal. This and other advances aimed at demonstrating superior photocathodes will be presented.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW025

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THPOW030

ELI Eectron Beam Line for Laser-plasma-driven Undulator X-ray Source

electron, undulator, quadrupole, laser

4005

A.Y. Molodozhentsev
KEK, Ibaraki, Japan
L. Pribyl
Czech Republic Academy of Sciences, Institute of Physics, Prague, Czech Republic

ELI LUX experiment of the ELI-Beamlines Project is based on electron beam, accelerated by the laser plasma wakefield. ELI LUX aims to deliver for users the X-ray beams with radiation length (0.4-4.5)nm and the peak brilliance up to 10²³ photons/(s mrad2 mm2 0.1% B.W.), which makes this source comparable with modern synchrotron sources. To provide small transverse size of the electron beam and small transverse beam divergence in the undulator, permanent quadrupole magnets with high gradient of the magnetic field up to 510 T/m are used in the electron beam line. In frame of this report we present main features of the designed electron beam line. 3D modeling of the magnetic field in the quadrupole magnets has been performed. Effects of the chromatic and spherical aberrations are taken into consideration. The electron beam dynamic is studied by using symplectic integration though the 3D field maps of the permanent quadrupole magnets. Effects of the space charge of the electron beam, beam collimation, injection and alignment errors and realistic field errors are discussed. Finally parameters of the photon beam, generated in compact undulator, are presented in this report.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW030

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THPOW035

Statistical Analysis Package for the Opearion Monitoring at the TLS

operation, database, Windows, target

4019

Y.K. Lin, H.H. Chen, H.C. Chen, S.J. Huang, C.H. Kuo, A.P. Lee, J.A. Li
NSRRC, Hsinchu, Taiwan

Machine operation parameters and interruptions to user beam at Taiwan Light Source (TLS) and Taiwan Photon Source (TPS) are recorded in databases. The data retrieve to TLS uses the File Transfer Protocol (FTP) with two separated databases 10 Hz and 0.1 Hz for quick or detail data analysis options. TPS data storage uses the open source database PostgreSQL. A statistical analysis package HISTORY has been writ-ten in Microsoft Visual C to perform operation monitor-ing and data mining. Operation and failure statistics func-tions are produced for performance evaluation and User Administration & Promotion Office user time statistics.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW035

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THPOW037

Simulated and Measured Magnetic Performance of a Double APPLE-II Undulator at the Canadian Light Source

undulator, multipole, polarization, dipole

4025

C.K. Baribeau, L.O. Dallin, J.M. Helfrich, T.M. Pedersen, M.J. Sigrist, W.A. Wurtz
CLS, Saskatoon, Saskatchewan, Canada

Assembly and shimming are underway for a double APPLE-II type elliptically polarized undulator (i.e. two magnet arrays installed side by side on a single support structure) at the Canadian Light Source. The device is planned to be installed in spring 2017. Extensive preparation was done prior to device assembly, particularly in development of a simulated annealing algorithm for magnet virtual shimming, as well as assembly procedures that minimized positional errors in the installed magnet blocks. In this paper we present measurements taken throughout the shimming process, and compare with predictions from a RADIA model where each magnet block was magnetized uniquely according to individual Helmholtz coil measurements.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW037

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THPOW048

Optimization of a Multipole Wiggler for Tps

wiggler, electron, radiation, permanent-magnet

4050

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

Taiwan Photon Source (TPS) is a synchrotron radia-tion facility with electron energy 3 GeV that was commissioned in 2015. Taiwan Light Source (TLS) with electron energy 1.5 GeV concurrently provides user time. Three beam lines of TLS supply photons of energy 6-18 keV for user experiments; these beam lines are served with an in-achromatic superconduct-ing wiggler (IASW, 3.1 T). This superconducting inser-tion device has the disadvantages of complicated maintenance and operation. A traditional multipole wiggler (MPW) magnet of hybrid type is hence planned to be installed in TPS to cover the range of photon energy of IASW for user experiments. For the design of the magnetic circuit, the side block and the extreme block are arranged surrounding a Permendur Vanadium cobalt steel pole that enhances the field strength and good field region of a MPW magnet. The dynamic integral field and the demagnetizing field of MPW magnet were estimated. The optimization of the pole dimensions and photon characteristics were simu-lated and are discussed in this work.

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THPOW049

Status of Insertion Devices at Taiwan Photon Source

undulator, vacuum, radiation, polarization

4054

T.Y. Chung, C.-H. Chang, C.H. Chang, M.-S. Chiu, J.C. Huang, C.-S. Hwang, J.C. Jan, C.-C. Kuo, Y.-C. Liu, F.H. Tseng, C.K. Yang
NSRRC, Hsinchu, Taiwan

The storage ring of Taiwan Photon Source (TPS) has eighteen short straight sections (length 7 m) and six long straight sections (length 12 m). In phase I, three elliptically polarized undulators of type APPLE II and seven in-vacuum undulators, which included four in-vacuum undulators and two elliptically polarized undulators in three double mini-βy sections, were installed. Commissioning of the insertion devices began in 2015 November. The influence of insertion devices on the electron beam and the results after compensation are presented. Problems during the commissioning induced by the electron beam and by radiation, and their solutions, are also explained. For insertion devices in phase II and for devices developed in TPS, the preliminary designs are presented herein, to cover from the VUV to the hard X-ray region.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW049

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THPOY049

Helical Undulator as a Source of Spectromicroscopy Beamline of ILSF

polarization, undulator, electron, radiation

4217

S. Amiri, A. Gholampour, M. Jafarzadeh, M. Lamehi, J. Rahighi
ILSF, Tehran, Iran
M. Lamehi, J. Rahighi
IPM, Tehran, Iran

Regarding user requirements of spectromicroscopy beamline such as high flux, small spot size, linear and circular polarization light, a helical undulator have been chosen as a source for this beamline. Radiation properties of the source e.g. flux, flux density, brilliance, size and divergence of the photon beam, power, power density, angular distribution of power and flux on the axis of the undulator have been considered by theoretical formula and using SPECTRA code. At the circular polarization, the first harmonic covers the energies in the 100-1300 eV range and for the linear polarization energy ranges, 100-1000 eV and 1000-1500 eV, are provided by the first and third harmonics respectively. In the case of circular and linear polarization mode, maximum flux in the central cone for maximum undulator strength are 4.5 × 10¹⁶ (ph/s) at kX=ky=3.6 and 2.4 × 10¹⁶ (ph/s) at K=5.
* James A. Clarke, "The science and technology of undulators and wigglers", 2004.
** H. Onuki, P. Elleaume, "WIGGLERS UNDULATORs and their APLICATIONS", 2003.

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THPOY050

Time Response of a Gridded X-ray Beam Ionization Chamber

ion, electron, experiment, radiation

4220

Y.H. Xu, Z.H. Sun
DongHua University, Songjiang, People's Republic of China
D.V. Campen, W.J. Corbett
SLAC, Menlo Park, California, USA
C.L. Li
East China University of Science and Technology, Shanghai, People's Republic of China
W.J. Zhang
University of Saskatchewan, Saskatoon, Canada

Recently, Quick-Scanning Extended X-ray Absorption Spectroscopy (QEXAS) has become an important tool for in-situ characterization of materials and measurement of associated electronic structure. In this case the time response of the ionization chamber affects the measurement resolution and therefore overall performance of the QEXAS system. Common parallel-plate ionization chambers have a step-response rise time of about 0.1 sec, which does not meet the requirements of QEXAS. To speed up the response, we constructed a gridded ionization chamber with variable bias voltage and optional background gas (N2 or He, respectively). To characterize the system we used a high-frequency beam chopper upstream of the ionization chamber and a high-speed, low-noise preamplifier to measure the step response of the chamber as a function of bias voltage and background gas conditions.

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reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY050

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