IPAC2019 - List of Keywords (photon)

Paper	Title	Other Keywords	Page
MOPGW053	Residual Gas Lifetime In High Energy Photon Source (HEPS)	scattering, electron, dynamic-aperture, vacuum	210
	S.K. Tian, H.S. Xu IHEP, Beijing, People’s Republic of China
	High vacuum has always been mandatory in particle accelerators. This is especially true for circular machines, where the beam makes thousands or millions turns, and beam lifetime is heavily affected by the residual gas scattering. At the beginning of storage ring operation the lifetime was very short mostly dominated by residual gas scattering. The residual gas lifetime is comprised of the elastic and inelastic scattering on electrons and elastic and inelastic scattering on nuclei. One usually calculates only the elastic scattering on nuclei (single Coulomb scattering) and inelastic scattering on nuclei (bremsstrahlung) of the residual gas scattering lifetime component. The analytic calculation the residual gas scattering lifetime and simulations of the beam interaction with the residual gas with code will be shown in this presentation
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPGW053
About •	paper received ※ 15 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019
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MOPMP035	Effect of Emittance Constraints on Monochromatization at the Future Circular e⁺e⁻ Collider	emittance, luminosity, collider, radiation	516
	M.A. Valdivia García, F. Zimmermann CERN, Meyrin, Switzerland
	Direct s-channel Higgs production in e+e− collisions is of interest if the collision energy spread can be comparable to the natural width of the standard model Higgs boson. At the Future Circular e⁺e⁻ Collider (FCC-ee), a monochromatization scheme could be employed in order to reduce the collision energy spread to the target value. This may be achieved by introducing a non-zero horizontal dispersion of opposite sign for the two colliding beams at the interaction point. In this case, the beamstrahlung increases the horizontal emittance in addition to energy spread and bunch length. The vertical emittance could either be tuned to a certain minimum value, possibly limited by the diagnostics resolution, or it could scale linearly with the horizontal emittance. For the FCC-ee at 62.5 GeV beam energy, we optimize the IP optics and beam parameters, considering these two different assumptions for the vertical emittance. We derive the maximum achievable luminosity as a function of collision energy spread for either case.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP035
About •	paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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MOPRB024	Beam-Gas and Beam-Thermal Photon Scattering in CEPC	scattering, background, detector, factory	626
	S. Bai, J. Gao, H. Geng, D. Wang, Y. Wang, C.H. Yu, Y. Zhang IHEP, Beijing, People’s Republic of China Y. Zhang University of Chinese Academy of Sciences, Beijing, People’s Republic of China
	The Circular Electron Positron Collider (CEPC) is a proposed Higgs factory with center of mass energy of 240 GeV to measure the properties of Higgs boson and test the standard model accurately. Beam loss background in detectors is an important topic at CEPC. Beam-Gas scattering (BG) and Beam-Thermal photon scattering (BTH), although not so serious as Radiative Bhabha scattering (RBB) and Beamstrahlung (BS), are also important components of the beam induced backgrounds at CEPC due to the beam lifetime. In this paper, we evaluated the beam-gas and beam-thermal photon scattering in simulation and designed collimators to suppress the radiation level on the machine and the detector.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB024
About •	paper received ※ 28 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB052	Gamma Factory at CERN: Design of a Proof-of-Principle Experiment	laser, experiment, electron, cavity	685
	Y. Dutheil, R. Alemany-Fernández, H. Bartosik, N. Biancacci, R. Bruce, P. Czodrowski, V. Fedosseev, B. Goddard, S. Hirlaender, J.M. Jowett, R. Kersevan, M. Kowalska, M. Lamont, D. Manglunki, J. Molson, A.V. Petrenko, M. Schaumann, F. Zimmermann CERN, Geneva, Switzerland S.E. Alden, A. Bosco, S.M. Gibson, L.J. Nevay JAI, Egham, Surrey, United Kingdom A. Apyan ANSL, Yerevan, Armenia E.G. Bessonov LPI, Moscow, Russia A. Bosco, S.M. Gibson, L.J. Nevay Royal Holloway, University of London, Surrey, United Kingdom F. Castelli Università degli Studi di Milano, Milano, Italy F. Castelli, C. Curatolo, L. Serafini INFN-Milano, Milano, Italy K. Kroeger FSU Jena, Jena, Germany A. Martens LAL, Orsay, France V. Petrillo Universita’ degli Studi di Milano, Milano, Italy M. Sapinski, T. Stöhlker GSI, Darmstadt, Germany G. Weber IOQ, Jena, Germany Y.K. Wu FEL/Duke University, Durham, North Carolina, USA
	The Gamma Factory (GF) initiative proposes to create novel research tools at CERN by producing, accelerating and storing highly relativistic partially stripped ion beams in the LHC rings and by exciting their atomic degrees of freedom by lasers, to produce high-energy photon beams. Their intensity would be several orders of magnitude higher than those of the presently operating light sources in the particularly interesting gamma-ray energy domain reaching up to 400 MeV. In this energy domain, the high-intensity photon beams can be used to produce secondary beams of polarized electrons, polarized positrons, polarized muons, neutrinos, neutrons and radioactive ions. Over the years 2017-2018 we have demonstrated that these partially stripped ion beams can be successfully produced, accelerated and stored in the CERN accelerator complex, including the LHC. The next step of the project is to build a proof of principle experiment in the SPS to validate the principal GF concepts. This contribution will present the initial conceptual design of this experiment along with its main challenge - the demonstration of the fast cooling method of partially stripped ion beams.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB052
About •	paper received ※ 19 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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MOPRB056	THz Radiator Based on Photonic Band Gap Crystal for SwissFEL	electron, GUI, experiment, FEL	693
	L. Shi, R. Ischebeck, S. Reiche PSI, Villigen PSI, Switzerland
	Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 701647. The electromagnetic radiation in 1-20 THz has many unique properties when it interacts with matter due to its non-ionizing excitation in matter. Especially the dynamics of the excited matter can be probed with the help of X-ray pulses at a free electron laser facility, e.g. SwissFEL, to deepen our understanding of a wide range of phenomena. Due to its high research potential, various means of THz generation have been proposed and demonstrated. We investigate preliminarily here its generation based on a relativistic electron bunch and a photonic band gap crystal (PBG) made of dielectric rods. The PBG provides additional degrees of freedom for the THz pulse tuning. Additionally, the unwanted radiation parts can be damped by the structure in order to minimize the deleterious beam dynamics effects. The crystal also promises the integration of generation, filtering and coupling for transport into a single piece.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB056
About •	paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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MOPRB088	Study of Fluctuations in Undulator Radiation in the IOTA Ring at Fermilab	experiment, undulator, electron, radiation	777
	I. Lobach University of Chicago, Chicago, Illinois, USA A. Halavanau, Z. Huang, V. Yakimenko SLAC, Menlo Park, California, USA K. Kim ANL, Argonne, Illinois, USA V.A. Lebedev, S. Nagaitsev, A.L. Romanov, G. Stancari, A. Valishev Fermilab, Batavia, Illinois, USA A.Y. Murokh RadiaBeam, Los Angeles, California, USA T.V. Shaftan BNL, Upton, Long Island, New York, USA
	We study turn-by-turn fluctuations in the number of emitted photons in an undulator, installed in the IOTA electron storage ring at Fermilab with an InGaAs PIN photodiode and an integrating circuit. Our study was motivated by the previous experiment . We propose a theoretical model for the experimental data from and in our own experiment we attempted to verify the model in an independent and more systematic way. Moreover, these fluctuations are an interesting subject for a study by itself, since they act as a seed for SASE in FELs. We improve the precision of the measurements from * by subtracting the average signal amplitude using a comb filter with a one-turn IOTA delay, and by using a special algorithm for noise subtraction. We obtain a reasonable agreement between our theoretical model and experiment. Along with repeating the experiment from , which was performed at a constant beam current, we also collect data for fluctuations in undulator light at different beam current values. Lastly, in our experiment we were able to see the transition from Poisson statistics to Super-Poisson statistics for undulator light, whereas in only the latter statistics was observed. * M. Teich et al., PRL, vol. 65, no. 27, p. 3393 (1990).
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB088
About •	paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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MOPRB089	Experimental Study of a Single Electron in a Storage Ring via Undulator Radiation	electron, undulator, experiment, radiation	781
	S. Nagaitsev, A.L. Romanov, G. Stancari Fermilab, Batavia, Illinois, USA A. Arodzero, A.Y. Murokh, M. Ruelas RadiaBeam, Santa Monica, California, USA I. Lobach University of Chicago, Chicago, Illinois, USA T.V. Shaftan BNL, Upton, Long Island, New York, USA
	A single electron orbiting around a ring and emitting single quanta at the rate of about one event per hundred turns could produce a wealth of information about physical processes in large traps (i.e. storage rings) for charged particles. It should be noted that Paul and Penning traps in the 1980s led to the Nobel prize for studying state and motion of single quantum particles, and just recently the Penning trap technique has enabled the measurement of a single proton magnetic moment with an unprecedented precision of 10 decimal places. The information from the storage ring traps could also be used for characterization of a quantum system as well as the "trap" itself, i.e. measuring properties of the storage ring lattice and electron interaction with the laser fields. Although, the interest in single electron quantum processes today is mostly academic in nature, the diagnostics and methodology developed for single electron radiation studies could find subsequent applications in a variety of applied disciplines in quantum technology, including quantum communications and quantum computing.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB089
About •	paper received ※ 15 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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TUYPLM1	XFEL Performance Achieved at PAL-XFEL	FEL, undulator, electron, emittance	1182
	H. Heo, M.-H. Cho, J.H. Han, H.-S. Kang, C. Kim, G. Kim, M.J. Kim, J.H. Ko, H.-S. Lee, C.-K. Min, I.H. Nam, K.-H. Park, C.H. Shim, H. Yang PAL, Pohang, Kyungbuk, Republic of Korea
	The hard X-ray free electron laser at Pohang Accelerator Laboratory (PAL-XFEL) successfully completed the commissioning of SASE and started user operation in late 2016. Since then, the facility has demonstrated excellent stability with very small timing jitter of about 20 fs, and commissioned the self-seeding system over a wide range of photon energies, etc. The talk will provide an overview of the last three years at the PAL-XFEL, including some detailed experimental results, as well as future prospects for the laboratory.
	Slides TUYPLM1 [7.516 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUYPLM1
About •	paper received ※ 20 May 2019 paper accepted ※ 24 May 2019 issue date ※ 21 June 2019
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TUZPLS2	Beam Dynamics Study in the HEPS Storage Ring	lattice, storage-ring, emittance, brightness	1203
	Y. Jiao, X. Cui, Z. Duan, Y.Y. Guo, P. He, X.Y. Huang, D. Ji, H.F. Ji, C. Li, J.Y. Li, X.Y. Li, C. Meng, Y.M. Peng, Q. Qin, S.K. Tian, J.Q. Wang, N. Wang, Y. Wei, G. Xu, H.S. Xu, F. Yan, C.H. Yu, Y.L. Zhao IHEP, Beijing, People’s Republic of China
	The High Energy Photon Source (HEPS) is the first high-energy diffraction-limited storage ring (DLSR) light source to be built in China, with a natural emittance of a few tens of pm rad and a circumference of 1360.4 m. After 10 years’ evolution, the accelerator physics design of the HEPS has been basically determined, with the ring consisting of 48 hybrid-7BAs with anti-bends and super-bends. This paper will discuss the accelerator physics studies of the HEPS storage ring, covering issues of lattice design, nonlinear optimization, collective effects, error correction, insertion devices, etc.
	Slides TUZPLS2 [9.517 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUZPLS2
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPMP007	DYVACS (DYnamic VACuum Simulation) Code: Calculation of Gas Density Profiles in Presence of Electron Cloud	electron, vacuum, proton, experiment	1244
	G. Sattonnay, S. Bilgen, B. Mercier LAL, Orsay, France V. Baglin CERN, Meyrin, Switzerland
	The computation of residual gas density profiles in particle accelerators is an essential task to optimize beam pipes and vacuum system design. In a hadron collider such as the LHC, the beam induces dynamic effects due to ion, electron and photon-stimulated gas desorption. The well-known VASCO* code developed at CERN in 2004 (and then PyVASCO) is already used to estimate vacuum stability and density profiles in steady state conditions. Nevertheless, some phenomena are not taken into account such as the ionization of residual gas by the electron clouds. Therefore, we propose an upgrade of this code by introducing electron cloud maps* to estimate the electron density and the ionization of gas by electrons, leading to an increase of both electron- and ion-induced desorption. Results obtained with the new code (called DYVACS for DYnamic VACuum Simulation) will be compared to pressure measurements in the VPS sector**** of the LHC. * A. Rossi, Tech. Rep., LHC Proj. Note 341 I. Aichinger, et al arXiv:1707.07525 * T. Demma et al Phys. Rev. Acceler. and Beams 10, 114401 (2007) **** B. Henrist et al, Proc. IPAC2014, Dresden
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP007
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPMP018	Feasibility Tests of a Vacuum System for SPring-8-II	vacuum, hardware, multipole, operation	1272
	K. Tamura, T. Bizen, M. Masaki, H. Ohkuma, M. Oishi, M. Shoji, S. Takahashi, Y. Taniuchi JASRI, Hyogo, Japan T. Bizen, M. Oishi, S. Takahashi RIKEN SPring-8 Center, Hyogo, Japan
	For SPring-8-II, the major upgrade of SPring-8, a test half-cell including permanent/electro magnets and a vacuum system was constructed, and hardware feasibility tests have been performed since 2017. Features of the SPring-8-II vacuum system are 1) introduction of the concept of a stainless steel 12 m-long integral chamber (LIC) with a welded structure, and 2) adoption of ex-situ baking of the chamber. The 12 m LIC with a narrow aperture, flangeless structure and a minimum number of bellows was designed so that the vacuum system could be installed without interference with the magnets of a narrow bore diameter aligned on girders with a severe packing factor. For replacement of the existing system with a new one in a short black-out period, the 12 m LIC is planned to be moved into the accelerator tunnel with keeping ultra-high vacuum (UHV) by closing thin gate valves at both ends, after evacuation to UHV by ex-situ baking and NEG activation. This presentation will overview the vacuum system, mainly the 12 m LIC, developed for the test half-cell, and describe the vacuum performance and the result of the assembly test conducted with the permanent/electro magnets.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP018
About •	paper received ※ 15 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019
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TUPMP019	Vacuum Performance of the NEG-coated Chamber for U#19 at PF-ring	vacuum, simulation, MMI, undulator	1276
	Y. Tanimoto, T. Honda, X.J. Jin, T. Nogami, R. Takai, M. Yamamoto KEK, Ibaraki, Japan
	At the Photon Factory storage ring (PF-ring) in KEK, a new APPLE-II type elliptically polarizing undulator (U#19) was installed in October 2018. The U#19 vacuum chamber is 4.1 meters in length, and the beam channel with a 15x90 elliptical profile and two cooling-water channels alongside were formed by extrusion of A6060-T6 aluminum alloy. The inner surface of the beam channel is coated with a Ti-Zr-V Non-Evaporable Getter (NEG) thin film, as it has a high effective pumping speed and a low Photon Stimulated Desorption (PSD) yield. After the installation of the U#19, the neighboring uncoated chambers and vacuum components were baked out at 200 °C for 44 hours, and then the NEG coating was activated at 160 °C for 48 hours. As a result, the pressures in the neighboring chambers reached as low as 10^-8 Pa. The conditioning of the vacuum chambers with irradiation of Synchrotron radiation evolved favorably as had been expected by a combined simulation of Synrad and Molflow, leading to a satisfactory recovery of the beam lifetime. Vacuum performance of the NEG-coated chamber was assessed especially by means of a residual gas analysis, and the properties of the NEG film were characterized by surface analyses including SEM, EDX, and XRD.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP019
About •	paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPMP035	Design of the Vacuum System of the FCC-ee Electron-Positron Collider	collider, vacuum, dipole, quadrupole	1319
	R. Kersevan, C. Garion CERN, Geneva, Switzerland
	The Future Circular Collider (FCC) Design Study includes the twin storage ring (FCC-ee) where electrons and positrons are stored and made to collide inside two detectors. The vacuum system of FCC-ee must be designed in order to deal with a lower-energy (45.6 GeV), high-current (1390 mA) Z-pole machine and at a later stage with a higher-energy (182.5 GeV) low-current (5.4 mA). The former machine is the most challenging one from the point of view of vacuum, since the photon-stimulated desorption (PSD) generated by the copious synchrotron radiation (SR) fans is quite large. While several concepts have been considered at the beginning, the design retained for the Conceptual Design Report (CDR) is one where the cross-section of the vacuum chamber (VC) in the arcs is a scaled-down version of the one implemented in the SUPERKEKB collider. Contrary to SUPERKEKB tough, the SR fans are absorbed by many short absorbers, with average spacing of 5.8 m. This allow a localization of the PSD gas load and to place lumped pumps in front of the SR absorbers, to maximize the pumping efficiency. The VC design is compatible with the design of the common-yoke dipoles and quadrupoles. The VC material is copper alloy. Optimization of the pressure profiles has been carried out by means of extensive coupled montecarlo simulations, for SR and molecular flow. For the higher energy versions of the machine, for which the SR spectra are characterized by critical energies well above the Compton edge, the localized absorbers facilitate also shielding the tunnel and any radiation-sensitive machine components from X-ray photon damage, by installing short high-Z material around the absorbers. The major features of the CDR relevant for vacuum will be highlighted in the paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP035
About •	paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPMP036	Results on the FCC-hh Beam Screen Sawtooth at the Kit Electron Storage Ring Kararesults on the Fcc-Hh Beam Screen Sawtooth at the Kit Electron Storage Ring Kara	radiation, vacuum, experiment, electron	1323
	L.A. Gonzalez, V. Baglin, I. Bellafont, P. Chiggiato, C. Garion, R. Kersevan CERN, Geneva, Switzerland I. Bellafont, F. Pérez ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain S. Casalbuoni, E. Huttel KIT, Eggenstein-Leopoldshafen, Germany
	Funding: * The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 654305. In the framework of the EuroCirCol collaboration (work package 4 "Cryogenic Beam Vacuum System"), the fabrication of the FCC-hh beam screen (BS) prototype has been carried out with the aim of testing it at room temperature on the Karlsruhe Institute of Technology (KIT) 2.5 GeV electron storage ring KARA (KArlsruhe Research Accelerator) light source. The BS prototype was tested on a beamline installed by the collaboration, named as BEam Screen TEstbench EXperiment (BESTEX). KARA has been chosen because its synchrotron radiation (SR) spectrum, photon flux and power match quite well the one foreseen for the 50+50 TeV FCC-hh proton collider. The BS prototype (2 m in length) was manufactured according to the base line design (BD) of the FCC-hh BS. It implements a saw-tooth profile designed to absorb the SR generated at the bending magnets. Also, a laser-ablated anti-electron cloud surface texturing [2] was applied at the BS inner walls. We present here the results obtained at BESTEX and the comparison of the results obtained during irradiation of the saw-tooth profile at different geometric configurations. This activity has been carried out in the framework of the EuroCirCol collaboration (work package 4 "Cryogenic Beam Vacuum System").*
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP036
About •	paper received ※ 13 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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TUPMP037	Recent Developments of Monte-Carlo Codes Molflow+ and Synrad+	simulation, vacuum, synchrotron, synchrotron-radiation	1327
	R. Kersevan, M. Ady CERN, Geneva, Switzerland
	Molflow+ and Synrad+ are Monte Carlo simulation tools for ultra-high vacuum and synchrotron radiation, respectively. Over the years they have become a common tool for designing and analysing the vacuum system of particle accelerators. This contribution gives a short summary about new features added since IPAC-14. Some highlights: In traditional Monte Carlo simulations, one simulated ’virtual’ particle represents a given number of physical molecules or photons. This is a weakness where the pressure or flux of the simulated system spans across multiple orders of magnitude. Synrad now supports low flux mode, a weighed Monte Carlo technique where the represented number of photons is reduced at every reflection, providing significantly better statistics at low flux regions. As for Molflow+, angle maps allow recording the molecules, directional distribution at any point, and then desorb a reduced gas quantity according to the recording. In linear systems, this allows iterative simulations that have been proven to treat systems up to 7 orders of magnitude of pressure difference. Without the new technique the computing time would be prohibitively slow on desktop computers, which is what most users of the two codes use. Both codes now have a built-in geometry builder that allows creating simple models through a set of 3D operations, and modifying those imported from CAD tools. Molflow+ has recently become open source, and it has been made compatible with, and tested on different versions of Linux and macOS. Examples of application of Molflow+ to novel Beam Gas Curtain detector and the design of the FCC-ee vacuum system will be given, alongside with some benchmarking runs against data published in literature. M. Ady, R. Kersevan, "Introduction to the Latest Version of the Test-particle Monte Carlo Code Molflow+", Proc. IPAC’14, Dresden, Germany, June 2014, pp. 2348-2350.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP037
About •	paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPMP038	Summary of Modelling Studies on the Beam Induced Vacuum Effects in the FCC-hh	vacuum, electron, collider, synchrotron	1331
	I. Bellafont, R. Kersevan, L. Mether CERN, Geneva, Switzerland
	Funding: The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 654305. EuroCirCol is a conceptual design study of a Future Circular Collider (FCC-hh) which aims to expand the current energy and luminosity frontiers that the LHC has established. The vacuum chamber of this 50 TeV, 100 km collider, will have to cope with unprecedented levels of synchrotron radiation power for proton colliders, dealing simultaneously with a tighter magnet aperture. Since the high radiation power and photon flux will release large amounts of gas into the system, the difficulty to keep a low level of residual gas density increases considerably compared with the LHC. This article presents a study of the beam induced vacuum effects for the FCC-hh novel conditions, the different phenomena which, owing to the presence of the beam, have an impact on the vacuum level of the accelerator. To achieve this, a novel beam screen has been proposed, featuring specific mitigating measures aimed at dealing with the beam induced effects. It is concluded that thanks to the new beam screen design, the vacuum level in the FCC-hh shall be adequate, allowing to reach the molecular density requirement of better than 10¹⁵ H₂/m3 with baseline beam parameters within the first months of conditioning.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP038
About •	paper received ※ 10 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPMP044	Special Aluminum Gasket Sealing of Non-circular Profile Flanges for the Accelerator UHV Systems	vacuum, impedance, experiment, emittance	1347
	G.Y. Hsiung NSRRC, Hsinchu, Taiwan
	Most of the beam ducts for the accelerators are not regularly the circular profile. Unfortunately, the conflat (CF-) flanges and the gaskets with non-circular profile were not commercially available. Besides, additional RF-contact bridges between the flanges must be built in for mitigating the impedance from the flange-gaps. In this presentation, various types of the aluminum (Al-) gaskets designed for the non-circular profile Al-flanges for the accelerator ultrahigh vacuum (UHV) systems are introduced. The surface of the Al-flange is flat to accommodate the special Al-gasket with knife edges for the sealing. Both the flange and gasket are manufactured by the oil-free Ethanol-CNC-machining process that any non-circular profile, e.g. rectangular, race-track, key-hole, etc., flanges can be precisely produced. The inner diameters of the gasket just suits those of the flanges that the impedance from the gap is significantly reduced. The flanges and gaskets after oil-free machining can be assembled immediately without any chemical cleaning. The experimental results for the as-mentioned non-circular profile Al-flanges reveal the UHV quality at pressure < 20 nPa after vacuum baking.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP044
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPMP046	Improvement the Bending Magnet Power Supply Performance for TPS Storage Ring	power-supply, storage-ring, feedback, controls	1353
	B.S. Wang, C.H. Huang, J.C. Huang, C.Y. Liu, K.-B. Liu, Y.S. Wong NSRRC, Hsinchu, Taiwan
	In the TPS (Taiwan Photon Source) facility, current stability of the electron beam depends on the bending magnet power supply and an orbit FOFB system to compensate the magnetic field. Due to the output current stability of the bending magnet power supply drifts with temperature so the orbit FOFB system should be applied to fine tune magnetic field and the photon beam should circulate in storage ring. In this paper, to stabilize the temperature of regulation circuit’s temperature box of the bending magnet power supply, the long-term output current stability is improve from ± 50ppm to ± 10ppm, and orbit FOFB system substantially reduce the tune X of beam position, effectively increasing the beam current stability and quality.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP046
About •	paper received ※ 12 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPMP050	Conceptual Design of the Diamond-II Vacuum System	vacuum, storage-ring, target, controls	1362
	M.P. Cox, C. Burrows, A.G. Day, J.A. Dymoke-Bradshaw, R.K. Grant, N.P. Hammond, X. Liu, A.G. Miller, H.S. Shiers, N. Warner DLS, Oxfordshire, United Kingdom
	The conceptual design of the vacuum system for the Diamond-II storage ring upgrade is described. Due to the small vessel cross section, typically 20 mm inside diameter (ID), and the consequent conductance limitation, distributed pumping is provided by non-evaporable getter (NEG) coating supplemented by ion pumps at high gas load locations. In-situ bakeout is incorporated to allow rapid recovery from both planned vacuum interventions and unplanned vacuum events. The vacuum vessels are constructed mainly from copper alloy while stainless steel is used in regions of AC magnets requiring low electrical conductivity. The proposed layout, engineering and build sequence of the vacuum system are described along with gas flow simulations confirming the vacuum performance advantages of NEG-coated vessels compared with uncoated vessels.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP050
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPGW013	Tune and Chromaticity Optimization at Bessy II for the Transverse Resonant Island Bucket Optics	optics, simulation, resonance, emittance	1411
	F. Armborst, P. Goslawski, A. Jankowiak HZB, Berlin, Germany
	Funding: Federal Ministry of Education and Research Transverse Resonant Island Buckets (TRIBs ) correspond to a second stable orbit, longitudinally winding around the core orbit in the transverse x-x^′-phasespace. The exploitation possibilities for stable TRIBs are under investigation at the third generation light source BESSY II in Berlin. The applicability for bunch separation is a main subject of these studies. Stable operation of TRIBs optics with a single or few bunches on the second orbit and a multibunch train on the main orbit has been shown . Photons emitted on the second orbit are well separated from those of the main orbit at all beamlines. This provides the possibility of bunch separation by beamline adjustment for the timing community without significant impact on the average brightness for other users. Simulations based on linear optics from closed orbits (LOCO) and on nonlinear optics derived from the measured chromaticity and tune shift with action (TSWA) predict this separation well. Friendly user experiments in 2018 confirmed these results. The scheduled upgrade BESSY VSR ** features simultaneously stored long and short bunches. Then TRIBs optics would in principle enable the separation of the different bunches at every beamline offering unique possibilities to our users. Simulations and measurements aiming to investigate further possible optimization of the TRIBs optics are presented. * F. Armborst, P. Goslawski et al, DOI: 10.18429/JACoW-IPAC2018-TUPML052 P. Goslawski, F. Armborst et al. DOI: 10.18429/JACoW-IPAC2017-WEPIK057 * A. Jankowiak et al., DOI: 10.5442/R0001
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW013
About •	paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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TUPGW046	Progress of Lattice Design and Physics Studies on the High Energy Photon Source	lattice, storage-ring, booster, injection	1510
	Y. Jiao, X. Cui, Z. Duan, Y.Y. Guo, P. He, X.Y. Huang, D. Ji, C. Li, J.Y. Li, X.Y. Li, C. Meng, Y.M. Peng, Q. Qin, S.K. Tian, J.Q. Wang, N. Wang, Y. Wei, G. Xu, H.S. Xu, F. Yan, C.H. Yu, Y.L. Zhao IHEP, Beijing, People’s Republic of China
	The High Energy Photon Source (HEPS) is an ul-tralow-emittance, kilometer-scale storage ring light source to be built in China. In this paper we will introduce the progress of the physics design and related studies of HEPS over the past year, covering issues in storage ring lattice design, injection and injector design, insertion device effects, error study and lattice calibration, collective effects, etc.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW046
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPGW085	A Hard X-Ray Compact Compton Source at CBETA	electron, laser, scattering, brilliance	1604
	K.E. Deitrick, C. Franck, G.H. Hoffstaetter, V.O. Kostroun, K.W. Smolenski Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA J. Crone, H.L. Owen UMAN, Manchester, United Kingdom B.D. Muratori STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
	Compton backscattering at energy recovery linacs (ERLs) promises high flux, high energy x-ray sources in the future, made possible by high quality, high repetition rate electron beams produced by ERLs. CBETA, the Cornell-BNL ERL Test Accelerator currently being built and commissioned at Cornell, is an SRF multi-turn ERL using Non-Scaling Fixed Field Alternating-gradient (NS-FFA) arcs. CBETA has high quality design parameters with an anticipated top energy of 150 MeV on the fourth pass. The expected parameters of a Compton source at CBETA include a top x-ray energy of over 400 keV with a flux on the order of 10¹² ph/s. In this paper, we present anticipated parameters and potential applications in science and engineering for this source.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW085
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPGW106	Present Status of the PF-ring and PF-AR Operations	operation, injection, undulator, ECR	1654
	R. Takai, T. Honda, Y. Kobayashi, S. Nagahashi KEK, Ibaraki, Japan
	The Photon Factory at KEK has been managing two synchrotron radiation sources, the PF-ring and PF-AR, for over 30 years. Although their operation time has been decreasing in recent years for budget reasons, continuous efforts to improve their performance have been made. In this paper, the operational status of these light sources for FY2018 is described. At the PF-ring, a first-generation undulator was renewed with the beamline components. A vacuum chamber for the new undulator was applied the NEG coating on the inner surface. This is the first attempt in Japanese light sources that the NEG-coated chamber is used for undulators. At the PF-AR, the top-up injection using the direct beam transport line was introduced to the user operation for the first time. Since modification of the beam injector LINAC for enabling simultaneous injection to the four different rings (the PF-ring, PF-AR, SuperKEKB HER and LER) was completed, this top-up operation no longer disturbs the operation of the other three rings. A low-energy operation of the PF-AR was also tested to secure more operation time within the limited budget.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW106
About •	paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPGW109	Conceptual Design of Vacuum Chamber for SPS-II Storage Ring	vacuum, storage-ring, impedance, emittance	1666
	T. Phimsen, S. Chaichuay, N. Juntong, P. Klysubun, S. Prawanta, P. Sudmuang, P. Sunwong SLRI, Nakhon Ratchasima, Thailand R. Deepan, A. Khamkham Suranaree University of Technology, Nakhon Ratchasima, Thailand
	The SPS-II is a 3 GeV ultralow emittance light source which is now under studied and designed by Thailand Synchrotron Light Research Institute (SLRI). The SPS-II storage ring is based on Double-Triple Bend Achromat (DTBA) cell with a circumference of 321.3 m aiming for horizontal emittance of less than 1 nm-rad. The compact lattice leaves narrow space for vacuum components. The small gap between poles of the magnets requires narrow vacuum chambers and limits the conductance of the chambers. The chambers will be made by stainless steel with a thickness of 1.5 mm. the cross section of beam duct is 40 mm × 16 mm elliptical shape. The bending chamber is designed as a long triangular chamber such that photon absorber can be installed as far from the light source as possible to lower the power density of the heat load. The overview of designed vacuum system for the SPS-II is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPGW109
About •	paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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TUPRB002	The Conceptual Design of a 36 GHz RF Undulator	undulator, cavity, electron, GUI	1676
	D. Zhu ASCo, Clayton, Victoria, Australia A.W. Cross, L. Zhang USTRAT/SUPA, Glasgow, United Kingdom Y.E. Tan AS - ANSTO, Clayton, Australia
	The CompactLight project supported by European H₂020 is to design a hard X-ray FEL facility beyond today’s state of the art. The project integrates photo injector, X-band acceleration and innovative compact short-period undulators together to make the machine more compact. RF undulator has an extraordinary advantage of working at very short undulator period. A conceptual design for a RF undulator at 36 GHz using a corrugated cylindrical waveguide operating in the HE11 mode is presented in this paper. Based on beam dynamics simulation and photon beam radiation simulations, the possibility of RF undulator to be used in CompactLight project is evaluated.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB002
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPRB005	Photon Polarisation Modelling of APPLE-II EPUs	polarization, undulator, operation, simulation	1687
	M.J. Sigrist, C.K. Baribeau, T.M. Pedersen CLS, Saskatoon, Saskatchewan, Canada
	The CLS is currently commissioning two APPLE-II in-sertion devices (IDs), see [1], and constructing two more that allow for operation in ’universal mode’, i.e. selecting arbitrary photon polarisation parameters. Two of these devices will operate in the soft x-ray range where there is expected to be a significant change to polarisation at the sample due to transmission effects of the beam line op-tics. Arbitrary polarisation selection of the ID will counter transmission effects and enable circular polarisation at the sample position. A polarisation model of the device is derived which allows for the calculation of both the Stokes parameters and photon energy for any set point of ID gap and phase. Numerical solutions of these equa-tions allow the calculation of gap and phase set points for any desired photon energy or polarisation. The results of the polarisation model are compared with numerical simulations of the synchrotron radiation calculated using measured magnetic fields at various polarisation modes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB005
About •	paper received ※ 13 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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TUPRB008	LUXE - a QED Experiment at the European XFEL	experiment, FEL, electron, laser	1694
	F. Burkart, R.W. Aßmann, R. Brinkmann, W. Decking, N. Golubeva, B. Heinemann, M. Hüning, J. List, M. Wing DESY, Hamburg, Germany M. Wing UCL, London, United Kingdom
	The proposed experiment aims to measure QED in the presence of strong fields and above the Schwinger critical field. An experiment is being considered at the European XFEL, which should be able to measure non-perturbative QED and its transition from the perturbative regime. This paper presents the current status of the LUXE (Laser und XFEL Experiment) design study. First layout considerations; accelerator beam line design, electron and laser beam parameters, radioprotection issues and first results of the start to end simulations will be presented and discussed in detail. An outlook concerning the implementation into the XFEL schedule and timeline of this experiment will be given.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB008
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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TUPRB020	Status of the European XFEL	FEL, operation, electron, MMI	1721
	W. Decking, F. Brinker, L. Fröhlich, R. Kammering, T. Limberg, S. Liu, D. Nölle, M. Omet, M. Scholz, T. Wamsat DESY, Hamburg, Germany
	The European XFEL is a Hard X-ray Free Electron Laser based on superconducting accelerator technology. In operation since 2017, it now serves 3 FEL beamlines simultaneously for user experiments. We will report on the present operation of the linear accelerator, the beam distribution to the various beamlines and the performance of the FEL radiators.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB020
About •	paper received ※ 15 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019
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TUPRB022	Triple Period Undulator	undulator, radiation, vacuum, operation	1728
	A. Meseck, J. Bahrdt, W. Frentrup, M. Huck, C. Kuhn, C. Rethfeldt, M. Scheer HZB, Berlin, Germany E.C.M. Rial DLS, Oxfordshire, United Kingdom
	Insertion devices are one of the key components of modern synchrotron radiation facilities. They allow for generation of radiation with superior properties enabling experiments in a variety of disciplines, such as chemistry, biology, crystallography and physics to name a few. For future cutting edge experiments in soft and tender x-rays users require high flux and variable Polarization over a wide photon energy range independent of other desired properties like variable pulse length, variable timing or Fourier transform limited pulses. In this paper, we propose a novel ID-structure, called Triple Period Undulator (TPU), which allow us to deliver a wide energy range from a few ten eV to a few keV at the same beamline with high flux and variable Polarization. The TPU are particularly interesting in context of BESSY III, the successor facility of BESSY II.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB022
About •	paper received ※ 15 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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TUPRB023	Considerations for the Ultrahard X-ray Undulator Line of the European XFEL	undulator, FEL, electron, operation	1732
	E. Schneidmiller, V. Balandin, W. Decking, M. Dohlus, N. Golubeva, D. Nölle, M.V. Yurkov, I. Zagorodnov DESY, Hamburg, Germany G. Geloni, Y. Li, S. Molodtsov, J. Pflüger, S. Serkez, H. Sinn, T. Tanikawa, S. Tomin EuXFEL, Schenefeld, Germany
	The European XFEL is a multi-user X-ray FEL facility based on superconducting linear accelerator. Presently, three undulators (SASE1, SASE2, SASE3) routinely deliver high-brightness soft- and hard- X-ray beams for users. There are two empty undulator tunnels that were originally designed to operate with spontaneous radiators in the range 20-90 keV. We consider, instead a possible installation of two FEL undulators. One of them (SASE4) is proposed for operation in a standard (7-25 keV) range as well as in ultrahard (25-100 keV) regime. We discuss a possible location and length of SASE4, modifications of electron beam transport, beam dynamics, choice of undulator technology, different operation modes (SASE and advanced lasing concepts) etc.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB023
About •	paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPRB025	Harmonic Lasing of the European XFEL in the Angstrom Regime	FEL, undulator, experiment, operation	1740
	E. Schneidmiller, F. Brinker, W. Decking, D. Nölle, M.V. Yurkov, I. Zagorodnov DESY, Hamburg, Germany N. Gerasimova, J. Grünert, N.G. Kujala, J. Laksman, Y. Li, J. Liu, Th. Maltezopoulos, I. Petrov, L. Samoylova, S. Serkez, H. Sinn, F. Wolff-Fabris EuXFEL, Hamburg, Germany
	Harmonic lasing in XFELs is an opportunity to extend the photon energy range of existing and planned X-ray FEL user facilities. Contrary to nonlinear harmonic generation, harmonic lasing can provide much more intense, stable, and narrow-band FEL beam. Another interesting application is Harmonic Lasing Self-Seeding (HLSS) that allows to improve longitudinal coherence and spectral power of a Self-Amplified Spontaneous Emission (SASE) FEL. This concept was successfully tested at FLASH2 in the range of 4.5 - 15 nm and at PAL XFEL at 1 nm. In this contribution we present recent results from the European XFEL where we successfully demonstrated operation of HLSS FEL at 5.9 A, thus pushing harmonic lasing for the first time into the Angstrom regime.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB025
About •	paper received ※ 09 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPRB031	FERMI Configuration for the Echo Enabled Harmonic Generation Experiment	laser, FEL, electron, experiment	1752
	E. Allaria, D. Castronovo, M. Cautero, I. Cudin, M.B. Danailov, B. Diviacco, L. Giannessi, M. Veronese, M. Zangrando Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
	The FERMI FEL-2 undulator line, normally operated in the double stage high gain harmonic generation with the fresh bunch (HGHG-FB) has been temporary modified to allow operating the FEL in the Echo Enabled Harmonic Generation (EEHG) scheme. An increase of the dispersion in the delay-line was required together with a replacement of the second stage modulator allowing the electron beam to resonantly interact with a second seed laser. Another critical component of the EEHG setup is a new manipulator installed in the delay-line chicane and hosting additional diagnostic components. In this work we describe in some detail these new components that allowed a successful demonstration of the EEHG at harmonics as high as 101.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB031
About •	paper received ※ 17 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPRB047	Proposal of the Reflection Hard X-Ray Self-Seeding at the SHINE Project	FEL, undulator, polarization, lattice	1792
	T. Liu, C. Feng SARI-CAS, Pudong, Shanghai, People’s Republic of China
	FEL self-seeding has been demonstrated a great advantage for the generation of a fully coherent and high brightness X-ray pulse experimentally. Generally, transmission monochromators with single crystal are adopted worldwide, such as LCLS, PAL-XFEL and European-XFEL. Recently, the self-seeding scheme based on a reflection monochromator with a double-crystal is proposed and demonstrated at SACLA successfully. In view of several potential advantages of the reflection type, here we give the proposal of the reflection monochromator based self-seeding and enable the application on the SHINE project. This manuscript is mainly focus on monochromator schemes at SHINE, instead of FEL simulations. We will present considerable schemes based on the specific undulator line.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB047
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPRB072	Compact APPLE X for Future SXL FEL and 3 GeV Ring at MAX IV Laboratory	undulator, polarization, vacuum, FEL	1833
	H. Tarawneh, P. N’gotta, L.K. Roslund, A. Thiel, K. Åhnberg MAX IV Laboratory, Lund University, Lund, Sweden
	An overview of the design of compact elliptically polarizing undulator with small round magnetic gap to provide full polarization control of synchrotron radiation in a more cost effective manner and consuming less built in space than the state of the art devices. This type of undulator is meant as source for the potential future Soft X-ray (SXL) FEL beamline using the linear accelerator at MAX IV. In addition, it offers new capabilities for future beamlines at the 3 GeV ring to use full polarization control to photon energies using the fundamental harmonic which are not attainable with today’s technology of the out-of-vacuum insertion devices at 3 GeV beam energy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB072
About •	paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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TUPRB081	Beam Motion and Photon Flux Dips during Injection at the Taiwan Photon Source	injection, kicker, betatron, vacuum	1848
	C.H. Huang, H.-P. Chang, C.H. Chen, Y.-S. Cheng, P.C. Chiu, C.-S. Fann, K.T. Hsu, K.H. Hu, C.Y. Liao, Y.-C. Liu, C.Y. Wu NSRRC, Hsinchu, Taiwan
	The Taiwan photon source (TPS) is a 3 GeV synchrotron light source now in routine operation at the NSRRC. At the beginning of beam commissioning, significant photon flux dips could be observed at injection due to a blow-up of the beam size. To eliminate this transient effect, all four kickers were rematched. The leakage field was shielded and the induced current loops at vacuum chambers in the injection area were also eliminated. These efforts reduced the horizontal betatron oscillations and orbit distortions to around one-tenth. In order to decrease the recovery time of photon dips during injection, the operational chromaticity was reduced to improve incoherent effects. After all those improvements, the photon flux dips during injection dropped to 30 % and the recovery time to less than 1 msec.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB081
About •	paper received ※ 17 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPRB088	Generation of High Peak Power Hard X-Rays at LCLS-II with Double Bunch Self-seeding	FEL, electron, laser, undulator	1863
	A. Halavanau, F.-J. Decker, Y. Ding, C. Emma, Z. Huang, J. Krzywiński, A.A. Lutman, G. Marcus, C. Pellegrini, D. Zhu SLAC, Menlo Park, California, USA
	Funding: This work was supported by the U.S. Department of Energy Contract No. DE-AC02-76SF00515. We propose to use existing LCLS copper S-band linac double bunch infrastructure to significantly improve LCLS-II hard X-ray performance. In our setup, we use the first bunch to generate a strong seeding X-ray signal, and the second bunch, initially traveling off-axis, to interact with the seed in the amplifier undulator and generate a near TW, 15 fs duration X-ray pulse in the 4 to 8 keV photon energy range. We investigate, via numerical simulations, the required transverse beam dynamics and the four crystals X-ray monochromator to be added to the existing LCLS-II beamline and discuss the final properties of the hard X-ray pulses and their potential application in high intensity, high-field physics experiments, including QED above the Schwinger critical field.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB088
About •	paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPRB089	Undulator Radiation Generated by a Single Electron	electron, undulator, experiment, radiation	1867
	A. Halavanau, Z. Huang, C. Pellegrini, T.O. Raubenheimer SLAC, Menlo Park, California, USA I. Lobach University of Chicago, Chicago, Illinois, USA S. Nagaitsev Fermilab, Batavia, Illinois, USA D. Seipt HZDR, Dresden, Germany
	Funding: This work was supported by the U.S. Department of Energy Contract No. DE-AC02-76SF00515. The facilities providing single electron beams are currently being commissioned at Fermilab and will be at SLAC. Recently, Fermilab’s IOTA ring routinely demonstrated circulation of a single electron at 100 MeV beam energy. Alternatively, SLAC is working on constructing LCLS-II an X-ray FEL driven by a 4 GeV SRF linac. A parasitic beamline, S30XL, is planned that will extract 4 GeV dark current from between the primary LCLS-II electron bunches. The dark current will be delivered to End Station A and can work independently of LCLS-II experiments. The dark current will be bunched at a frequency of 46 MHz while extracted current varied from single electrons to 10’s of nA. In the present paper, we estimate the feasibility of propagating single electron beams through a conventional undulator, placed in the IOTA and S30XL beamlines. We explore the possible observable effects and experimental parameters range. In addition, we focus on potential applications of such beams in systems for high fidelity quantum measurements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB089
About •	paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPRB090	Preliminary Considerations of Atomic Inner-Shell X-Ray Laser for Self-Seeding at LCLS-II	FEL, simulation, radiation, experiment	1871
	A. Halavanau, C. Pellegrini, J. Wu SLAC, Menlo Park, California, USA A.I. Benediktovitch EuXFEL, Hamburg, Germany N. Rohringer Max Planck Institute for the Physics of Complex Systems, Dresden, Germany
	Funding: This work was supported by the U.S. Department of Energy Contract No. DE-AC02-76SF00515. The atomic inner-shell X-ray lasing, induced by the irradiation of focused XFEL SASE pulses, was demonstrated in gases, liquid jets and solids. In this proceeding, we discuss the possible use of this concept in self-seeding scheme at LCLS-II. We provide a preliminary study of different lasing media and corresponding SASE XFEL parameters. For the case of noble gas inner-shell X-ray laser, we study the requirements for gas pressure and XFEL pulse focusing. Finally, we discuss possible designs of this system and its advantages in LCLS-II operations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB090
About •	paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPRB094	New Superconducting Undulator Magnetic Measurement System for the Advanced Photon Source Upgrade	GUI, undulator, vacuum, storage-ring	1881
	M. Kasa, E.R. Anliker, Y. Ivanyushenkov, Y. Shiroyanagi ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. Magnetic measurements of existing superconducting undulators (SCUs) are performed under normal operating conditions after final assembly into the cryostat and before installation on the Advanced Photon Source (APS) storage ring. The SCU cryostat for the APS upgrade has been scaled in length from the current cryostat and will contain two SCUs. While some aspects of the current measurement system are desirable to retain, such as a room temperature measurement bore, scaling the current measurement techniques to the length required for the APS upgrade cryostat is not feasible. To address these challenges a unique system has been developed at the APS to allow measurements of the two SCU magnets in the long cryostat. The measurement system developed allows the magnets to be operated under normal operating conditions while maintaining the measurement equipment at room temperature and atmospheric pressure.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB094
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPRB095	Superconducting Undulators for the Advanced Photon Source Upgrade	undulator, vacuum, electron, operation	1884
	M. Kasa, E.R. Anliker, J.D. Fuerst, Q.B. Hasse, Y. Ivanyushenkov, I. Kesgin, Y. Shiroyanagi, E. Trakhtenberg ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357. The magnetic devices group at the Advanced Photon Source (APS) is in the process of designing and developing superconducting undulators (SCUs) for the APS upgrade. While similar in some aspects to previous SCU systems currently in operation at the existing APS, the new SCU systems will include two undulators installed in one cryostat which occupies an entire straight section of the storage ring. Straight sections containing planar undulators will either be configured as ’in-line’, where the two undulators behave as one source, or canted, where the two undulators are operated independently. Also under development is a superconducting arbitrary polarizing emitter (SCAPE) which can produce planar, elliptical, and helical undulator fields.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB095
About •	paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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TUPTS026	Negative Electron Affinity GaAs Cathode Activation With CsKTe Thin Film	cathode, electron, vacuum, gun	1986
	M. Kuriki KEK, Ibaraki, Japan K. Masaki HU/AdSM, Higashi-Hiroshima, Japan
	Funding: This work is partly supported by Japan-US Cooperative grant for scientific studies, Grant aid for scientific study by MEXT Japan (KAKENHI). Negative Electron Affinity (NEA) GaAs cathode is an unique device which can generate a highly polarized electron beam with circularly polarized light. The NEA surface is conventionally made by Cs and \rm O/NF₃ adsorption on the cleaned p-doped GaAs crystal, but the robustness of the cathode is very limited, so that the electron emission is easily lost by residual gas adsorption, ion back-bombardment, etc. To improve the cathode robustness, NEA activation with a stable thin-film on GaAs surface according to Hetero junction hypothesis has been proposed by the author. An experiment of the NEA activation with CsKTe thin film was carried out at Hiroshima University and a significant electron emission with 1.43 eV photon was observed which strongly suggested NEA activation. The cathode showed 16 to 20 times improvement of lifetime comparing to GaAs activated with Cs and O.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS026
About •	paper received ※ 26 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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TUPTS069	A Plasmonic Niobium Photocathode for SRF Gun Applications	cathode, gun, laser, cavity	2079
	F.E. Hannon JLab, Newport News, Virginia, USA G. Andonian, L.H. Harris RadiaBeam, Marina del Rey, California, USA
	The typical quantum efficiency of niobium is of the order 10^-4, whilst also requiring UV lasers for emission. This paper presents the results of a plasmonic niobium surface that operates with IR laser via multiphoton emission.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS069
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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TUPTS089	Observations of the Femtosecond Laser-Induced Emission From the Diamond Field Emitter Tips	laser, electron, cathode, experiment	2130
	E.I. Simakov, H.L. Andrews, R.L. Fleming, D. Kim, V.N. Pavlenko LANL, Los Alamos, New Mexico, USA D.S. Black, K.J. Leedle Stanford University, Stanford, California, USA
	Funding: Los Alamos National Laboratory LDRD Program We present the results of experimental observation of emission from single diamond field emitter tips when triggered by an ultra-short laser pulse. Diamond field emitter array (DFEA) cathodes were originally proposed for applications that require large current densities. DFEAs represent periodic arrays of diamond pyramids with micron-size dimensions and tips with diameters of the order of tens of nanometers. DFEAs are known to produce significant currents in field emission regime under direct current (DC) fields and in radio-frequency (RF) guns. It has been proposed that single diamond tip emitters can be employed for production of small tightly focused electron beams for dielectric laser accelerators (DLAs) that accelerate particles using the energy of light produced by infrared lasers. To generate short electron bunches required by DLAs diamond pyramids may be triggered with a laser. We have recently observed emission produced by a single diamond pyramid when triggered by a laser at different wavelengths from 256 nm to 2020 nm. We have conducted studies with the goal to understand mechanism of the emission. We clearly observed the change in emission mechanism when the wavelength changed from 256 nm to 512 nm. We believe that while the emission at 256 nm is a clear photoemission, the emission at longer wavelengths is likely the field emission caused by intense electric fields of the laser.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS089
About •	paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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WEPMP009	Renovation of Off-Axis Beam Injection Scheme for Next-Generation Photon Sources	septum, injection, vacuum, kicker	2318
	S. Takano, K. Fukami, C. Kondo, M. Masaki, M. Oishi, M. Shoji, K. Tamura, T. Taniuchi, T. Watanabe, K. Yanagida JASRI, Hyogo, Japan H. Akikawa, K. Sato Nihon Koshuha Co. Ltd, Yokohama, Japan K. Fukami, T. Hara, T. Inagaki, C. Kondo, M. Oishi, S. Takano, H. Tanaka, T. Watanabe RIKEN SPring-8 Center, Hyogo, Japan K. Hamato, J. Kataoka, K. Kusano, K. Ogata, Y. Saito TOKIN, Sendai, Miyagi, Japan
	Funding: Work supported by Ministry of education, culture, sports, science and technology JAPAN (MEXT). Photon sources are looking for performance upgrades by pursuing higher photon brilliance and coherence these years. The trend is pushing the lattice design to lower the beam emittance, which naturally results in the narrower dynamic aperture. One bottleneck in the upgrades is a beam injection system capable of accumulating required beam intensity and keeping top-up operations with such narrow apertures. Beam injection with a nonlinear kicker and transverse/longitudinal on-axis injections are now in the limelight. However, these techniques still need time to be put into practical use. We take an alternative approach for the SPring-8 upgrade, SPring-8-II, renovating the off-axis beam injection scheme to address the following requirements for the coming diffraction-limited storage rings (DLSRs): minimizing of both injection beam amplitude and perturbation to stored beam, and topping-up functionality. This presentation will overview the renewed off-axis beam injection scheme and report the development status of the following three key components: 1) permanent magnet based DC septum magnet, 2) in-vacuum pulse septum magnet, and 3) twin kickers driven by a single solid state pulser.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP009
About •	paper received ※ 10 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPGW031	Measurement of Cherenkov Diffraction Radiation from a Short Electron Bunches at t-ACTS	electron, radiation, experiment, detector	2536
	S. Ninomiya, H. Hama, F. Hinode, K. Kanomata, S. Kashiwagi, S. Miura, N.M. Morita, T. Muto, I. Nagasawa, K. Nanbu, H. Saito, K. Takahashi, H. Yamada Tohoku University, Research Center for Electron Photon Science, Sendai, Japan
	Cherenkov Diffraction Radiation (ChDR) can be considered as a tool of non-destructive beam diagnostics. It also has the feature that the photon flux of ChDR is proportional to the thickness of the dielectric used as the radiator and can be much larger than ordinary diffraction radiation. An experimental set-up for the measurement of coherent ChDR from short electron bunches of about 100 fs is being prepared at t-ACTS, Tohoku University. Results of a basic experimental study about coherent ChDR will be presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW031
About •	paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPGW062	Synchrotron Light Diagnostic Beamline Design for HEPS Storage Ring	emittance, diagnostics, storage-ring, lattice	2619
	D.C. Zhu, J.S. Cao, Y.F. Sui, J.H. Yue IHEP, Beijing, People’s Republic of China
	Funding: National Nature Science Foundation of China(11605213) High Energy Photon Source (HEPS) is a 6 GeV ul-tralow-emittance storage ring light source to be built in Beijing, China. With a multiple-bend achromat lattice design, the storage ring is expected to achieve an ul-tralow emittance of 34 pm.rad. The horizontal and verti-cal beam sizes will be in the sub-10 μm level. Beam emit-tance will be measured with x-ray diagnostic beamline at a low dispersion bending magnet source point. A visible light beamline will be designed to measure the bunch length and purity. In this paper, we will introduce the x-ray beamline, which combine with different techniques to resolve beam sizes and emittance.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW062
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPGW077	Recent Results using Incoherent Cherenkov Diffraction Radiation for Non-Invasive Beam Diagnostics	radiation, experiment, diagnostics, beam-diagnostic	2654
	M. Bergamaschi, R. Kieffer, T. Lefèvre, S. Mazzoni CERN, Geneva, Switzerland A. Aryshev KEK, Ibaraki, Japan P. Karataev Royal Holloway, University of London, Surrey, United Kingdom P. Karataev, K. Lekomtsev JAI, Egham, Surrey, United Kingdom A. Potylitsyn TPU, Tomsk, Russia A. Schloegelhofer TU Vienna, Wien, Austria
	When a relativistic charged particle travels at a short distance from the surface of dielectric material Cherenkov Diffraction Radiation (ChDR) is produced inside the dielectric. Recent observation of incoherent ChDR in the visible spectrum has opened the possibility of using this radiation for non-invasive beam size and position measurements. An experimental test to study this technique for highly directional beam position measurement has been initiated on the CLEAR facility at CERN, whilst another experimental investigation is underway at the Accelerator Test Facility 2 (ATF2) at KEK, Japan, to measure the resolution limit of ChDR for beam imaging diagnostics. This contribution presents the latest experimental results from both of these test facilities.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW077
About •	paper received ※ 01 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPGW087	Control System Studio to Monitor Front End and Beamlines Status as well as Light Source Stability	electron, status, operation, controls	2687
	W.Y. Lin, B.Y. Chen, C.S. Huang, C.H. Kuo, T.Y. Lee NSRRC, Hsinchu, Taiwan
	The primary task during a shift change at the Taiwan Photon Source Accelerator Operations team is to know the exact status of the machine, so that problems can be discovered immediately and solved when the machine behaves abnormal. To provide a stable beam during top-up operation, it is necessary to monitor closely the stability of the light source, of front end areas and beamlines. Should any abnormality occur, the operator would initiate initial troubleshooting and adjustments, inform users and sub-system staff members and perform subsequent first anal-yses and system optimizations. In this article, we describe how to sort through the nec-essary information with the Control System Studio (CSS) design page. There are currently seven beamlines in operation at the Taiwan Photon Source (05, 09, 21, 23, 25, 41, 45) and more new beamlines will be added in the future. Com-pared with other tools, CSS is intuitive and easy to revise. No matter weather adding new parameters or changing settings, the operation team can quickly get familiar with the machine status and perform an interface upgrade.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW087
About •	paper received ※ 27 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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WEPGW093	Commissioning of the Prototype for a New Gas Curtain Beam Profile Monitor Using Beam Induced Fluorescence for HL-LHC	electron, gun, background, experiment	2709
	A. Salehilashkajani, C.P. Welsch, H.D. Zhang The University of Liverpool, Liverpool, United Kingdom M. Ady, N. Chritin, J. Glutting, O.R. Jones, R. Kersevan, T. Marriott-Dodington, S. Mazzoni, A. Rossi, G. Schneider, R. Veness CERN, Geneva, Switzerland P. Forck, S. Udrea GSI, Darmstadt, Germany C.P. Welsch, H.D. Zhang Cockcroft Institute, Warrington, Cheshire, United Kingdom
	Funding: This work is supported by the HLLHCUK project and the STFC Cockcroft Institute core grant No. ST/G008248/1. A new supersonic gas-jet curtain based beam profile monitor is under development for minimally invasive simultaneous transverse profile diagnostics of proton and electron beams, at pressures compatible with LHC. The monitor makes use of a thin gas-jet curtain angled at 45 degrees with respect to the charged particle beams. The fluorescence caused by the interaction between the curtain and the beam can then be detected using a dedicated imaging system to determine its transverse profile. This contribution details design features of the monitor, discusses the gas-jet curtain formation and presents various experimental tests, including profile measurements of an electron beam using nitrogen and neon curtains. The gas-jet density was estimated by correlating it with the number of photons detected by the camera. These measurements are then compared with results obtained using a movable pressure gauge. This monitor has been commissioned in collaboration with CERN, GSI and the University of Liverpool. It serves as a first prototype of a final design that will be placed in the LHC beam line to measure the profile of the proton beam.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW093
About •	paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019
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WEPGW096	Development of Supersonic Gas-Sheet-Based Beam Profile Monitors	electron, background, radiation, monitoring	2717
	H.D. Zhang, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom M. Ady, J. Glutting, O.R. Jones, T. Marriott-Dodington, S. Mazzoni, A. Rossi, G. Schneider, R. Veness CERN, Geneva, Switzerland P. Forck, S. Udrea GSI, Darmstadt, Germany A. Salehilashkajani, C.P. Welsch, H.D. Zhang The University of Liverpool, Liverpool, United Kingdom
	Funding: HL-LHC project funded by STFC and CERN, and the STFC Cockcroft core grant No. ST/G008248/1. Non-destructive beam profile monitoring is very desirable, essentially for any particle accelerator but particularly for high-energy and high-intensity machines. Supersonic gas jet-based monitors, detecting either the ionization or fluorescence of a gas sheet interacting with the primary beam to be characterized, allow for minimally invasive measurements. They can also be used over a wide energy range, from keV to TeV beams. This contribution gives an overview of the jet-based ionization and fluorescence beam profile monitors which have been developed, built and tested at the Cockcroft Institute. It discusses gas sheet generation, vacuum considerations, choice of gas species and detection methods.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW096
About •	paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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WEPGW120	Fluorescence-Based Imaging Diagnostic for High Average Power Deuteron Beam	neutron, diagnostics, quadrupole, target	2777
	R.A. Marsh, S.G. Anderson, D.J. Gibson, J. Hall, B. Rusnak 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. Lawrence Livermore National Laboratory is developing an intense, high-brightness fast neutron source to create sub-millimeter-scale resolution neutron radiographs and imag-es. An intense source (10¹¹ n/s/sr at 0 degrees) of fast neutrons (10 MeV) will be produced using a pulsed 7 MeV, 300μAmp average-current commercial deuteron accelerator producing a small (1.5 mm diameter) beam spot size to achieve high resolution. The high average power beam is a challenge for diagnostics, and a precise full power emittance measurement is critical to benchmark the system performance. A fluorescence-based beam profiling diagnostic has been selected, and this paper presents the design for the system including chamber layout, light yield calculations, and imaging system details.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW120
About •	paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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WEPRB116	X-ray Pinhole Camera for Emittance Measurements in Solaris Storage Ring	emittance, storage-ring, radiation, diagnostics	3084
	A. Kisiel, A.M. Marendziak, M. Ptaszkiewicz, A.I. Wawrzyniak Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland
	X-ray pinhole camera is widely used system for the transverse beam profile measurement and emittance feedback. However this method is predominantly applied to the middle and high energy storage rings. At Solaris storage ring with the nominal energy of 1.5 GeV, the design of the beamline was modified to provide sufficient X-ray photon flux for proper imaging. The successful installation and commissioning of the X-ray pinhole beamline allows now to measure the emittance and helps in proper 3rd harmonic cavities tuning against the coupled bunch mode instabilities. The paper describes the design details, simulations and measurement results obtained during the beamline operation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB116
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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WEPTS104	Synchrotron Radiation Reflections in the CLIC Beam Delivery System	detector, collider, synchrotron, radiation	3363
	D. Arominski, A. Latina, A. Sailer, D. Schulte CERN, Meyrin, Switzerland
	Synchrotron radiation (SR) reflection is an important issue for future linear colliders. High fluxes of the SR might impact the performance of the detector, through irradiation of the forward luminosity and beam quality calorimeters or of the innermost layers of the vertex detector. The photon reflections depend on the beam pipe apertures’ size, their shape, and materials used with various surface roughness. In this work, we present a study of SR including reflection for the 380 GeV and 3 TeV beam parameters and optics of the Compact Linear Collider’s Final Focus System. The simulations of the SR reflections using the Synrad+ software are presented and the impact on the detector is discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS104
About •	paper received ※ 29 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THYPLM1	Development of the Vertically Polarizing Hard X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project	undulator, operation, free-electron-laser, electron	3408
	M. Leitner, D. Arbelaez, J.N. Corlett, A.J. DeMello, L. Garcia Fajardo, D. Leitner, S. Marks, K.A. McCombs, T. Miller, D.V. Munson, J. Niu, K.L. Ray, D.A. Sadlier, D. Schlueter, E.J. Wallén LBNL, Berkeley, California, USA H. Bassan, D.E. Bruch, D.S. Martinez-Galarce, H.-D. Nuhn, M. Rowen, Z.R. Wolf SLAC, Menlo Park, California, USA C.W. Chen NSRRC, Hsinchu, Taiwan
	Funding: Work supported by the Director, Oﬃce of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231. The Linear Coherent Light Source II (LCLS-II) is a free electron laser facility currently in its final construction stage at Stanford Linear Accelerator Center. The project includes two variable-gap, hybrid-permanent-magnet undulator lines: A soft x-ray undulator line with 21 undulator segments optimized for a photon energy range from 0.2 keV to 1.3 keV and a hard x-ray undulator line with 32 undulator segments designed for a photon energy range from 1.0 keV to 25.0 keV. This paper focuses on the design, development, and performance of the hard x-ray undulator line which utilizes uniquely-developed, vertically-polarizing undulators. To fully compensate the magnetic force throughout the entire gap range these devices incorporate non-linear spring systems which permit the construction of relatively compact undulators. However, significant magnetic field repeatability challenges have been encountered during prototyping of this novel design. The paper describes the innovative design improvements that were implemented which lead to reaching the LCLS-II required performance. These final design solutions can also be advantageous improving the operation of any future undulator design.
	Slides THYPLM1 [28.498 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THYPLM1
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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THYYPLS3	A Remote-Controlled Robot-Car in the TPS Tunnel	controls, radiation, operation, laser	3435
	T.Y. Lee, B.Y. Chen, T.W. Hsu, B.Y. Huang, C.H. Kuo, W.Y. Lin NSRRC, Hsinchu, Taiwan
	A remote-controlled robot-car named ’PhotonBot’ was put into the TPS accelerator tunnel and is equipped with a 360 degrees LiDAR for SLAM and navigation, two cameras for perception and first-person view, and a thermal imaging system. The robot can be remotely controlled and can send data to a remote PC through Wi-Fi. With SLAM, it can go more freely without being restricted to a designated path. In order to ensure it can work continuously, there is a wireless charging station in case of a low battery.
	Slides THYYPLS3 [18.013 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THYYPLS3
About •	paper received ※ 09 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPMP008	Feasibility Study on Mo-99 Production Using Hybrid Method Based on High Power Electron Accelerator	target, neutron, radiation, electron	3462
	A. Taghibi Khotbeh-Sara, F. Rahmani KNTU, Tehran, Iran F. Ghasemi NSTRI, Tehran, Iran H. Khalafi AEOI, Tehran, Iran M. Mohseni Kejani Shahid Beheshti University, Tehran, Iran
	In this study, the idea 99Mo production using hybrid method based on electron accelerator has been pre-sented. Two different main production channels of 100Mo(γ,n)99Mo and 98Mo(n,γ)99Mo can be used for 99Mo production in this system. By considering high power Linac (30 MeV, 1 mA in average beam current) and one-stage approach, the calculation of 100Mo(γ,n)99Mo reactions in the optimized 100Mo target in two different designs (strip and disc) has been simu-lated. It is predicted that about 61 and 53 Ci of 99Mo activity per 24-hour irradiation on the strip target and the disc plates can be achieved, respectively. The threshold energy of photoneutron at 100Mo is about 9 MeV, so a large part of bremsstrahlung photons cannot participate in photoneutron reaction. For feasibility study, new hybrid approach has been tested by 10 MeV Rhodotron. Due to the low threshold of photo-neutron in deuteron (about 2.2 MeV) and significant low energy photons in 100Mo, photoneutron flux is available. So, Molybdenum target in heavy water Tank increases the production yield of 99Mo using neutron absorption reaction in 98Mo. The total activity of 99Mo has been predicted about 0.23 Ci per 24 hours e-beam irradiation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP008
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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THPMP049	Sequential Excitation Scheme for Laser Stripping of Hydrogen Ion Beams	laser, electron, cavity, proton	3558
	Y. Liu, A.V. Aleksandrov, S.M. Cousineau, T.V. Gorlov, A. Rakhman ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. Resonant laser excitation of the electron in a hydrogen atom is essential to achieve high-efficiency laser stripping of hydrogen ion (H⁻) beam. In the laser stripping experiments recently carried out at SNS, an ultra-violet (UV) laser was used to excite the electrons in 1-GeV hydrogen atoms from the n=1 state to the n=3 state. In this talk, we propose a sequential resonant excitation scheme by using two laser beams to excite electrons in a sequence of two steps: from the n=1 state to the n=2 state and from the n=2 state to any higher state. The advantages of the sequential resonant excitation scheme include (1) lower laser power requirement due to higher transition probability in the first excitation step and (2) possibility of shifting the stripping laser wavelength from UV regime to longer wavelengths. An application of the sequential resonant excitation scheme in combination with the double-resonance optical cavity technology to the laser stripping of 1.3-GeV H⁻ beam (envisioned in the SNS proton power upgrade project) will be described.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP049
About •	paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019
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THPGW014	Tolerance Studies and Limitations for Photonic Bandgap Fiber Accelerators	laser, acceleration, simulation, electron	3605
	L. Genovese, R.W. Aßmann, U. Dorda, M. Kellermeier, W. Kuropka, F. Lemery, F. Mayet DESY, Hamburg, Germany W. Kuropka, F. Mayet University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
	Laser-driven hollow core photonic bandgap (PBG) fibers were proposed by Lin in 2001 as high-gradient accelerators. The central defect in the transversely periodic lattice supports an accelerating mode for synchronous acceleration in the ultra-relativistic regime. The optical frequencies in such dielectric laser accelerators motivate a sensitivity and tolerance study to overcome manufacturing imperfections. Finally we discuss the propagation characteristics of Lin-fibers and find that small-bandwidth (~ns) pulses would be needed for efficient acceleration over longer distances.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW014
About •	paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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THPGW033	Numerical Study of Photonic-Crystal-Based Dielectric Accelerators	GUI, acceleration, electron, impedance	3653
	G. Torrisi, L. Celona, S. Gammino, D. Mascali, G. Sorbello INFN/LNS, Catania, Italy C. De Angelis, A. Locatelli University of Brescia, Brescia, Italy G.S. Mauro INFN/LNL, Legnaro (PD), Italy G. Sorbello University of Catania, Catania, Italy
	All-dielectric electromagnetic band gap (EBG) waveguides structures promise significant improvement of accelerating gradient of laser-driven acceleration with the potential to miniaturize the accelerator itself. In this work we study photonic crystal structures designed for acceleration of relativistic electrons. We explore the performance of the all-dielectric EBG accelerating waveguide structures thanks to full wave electromagnetic simulations of couplers and accelerating waveguides. The characteristic interaction impedance, accelerating gradient and all the key parameters that are typically used to characterize linear accelerators are evaluated and used to compare the properties of the accelerating mode field distribution in different geometries.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW033
About •	paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPGW051	MCP Based Detectors of European XFEL	FEL, detector, radiation, electron	3703
	E. Syresin, O.I. Brovko, A.Yu. Grebentsov JINR, Dubna, Moscow Region, Russia W. Freund, J. Grünert EuXFEL, Schenefeld, Germany M.V. Yurkov DESY, Hamburg, Germany
	Radiation detectors based on microchannel plates (MCP) are used for measurements of the SASE process of the European XFEL. Detectors operate in a wide dynamic range from the level of spontaneous emission to the saturation level (between a few nJ and 25 mJ) and in a wide wavelength range from 0.05 nm to 0.4 nm for SASE1 and SASE2 and from 0.4 nm to 4.43 nm for SASE3. Photon pulse energies are measured by the MCPs with an anode and by a photodiode. The MCP imager measures the photon beam image with a phosphor screen. Three MCP detectors are installed, one behind each SASE undulator (SASE1, SASE2, and SASE3). Calibration and first experiments with the MCP detectors are under discussion.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW051
About •	paper received ※ 29 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPGW061	The K12 Beamline for the KLEVER Experiment	target, detector, experiment, background	3726
	M.W.U. Van Dijk, D. Banerjee, J. Bernhard, M. Brugger, N. Charitonidis, N. Doble, L. Gatignon, A. Gerbershagen, E. Montbarbon, B. Rae, M.S. Rosenthal, B. Veit CERN, Geneva, Switzerland G. D’Alessandro JAI, Egham, Surrey, United Kingdom M. Moulson INFN/LNF, Frascati, Italy
	The KLEVER experiment is proposed to run in the CERN ECN3 underground cavern from 2026 onward. The goal of the experiment is to measure BR(KL -> pi0 nu nu), which could yield information about potential new physics, by itself and in combination with the measurement of BR(K+ -> pi+ nu nu) of NA62. A full description will be given of the considerations in designing the new K12 beamline for KLEVER, as obtained from a purpose made simulation with FLUKA. The high intensities required by KLEVER, 2·10¹³ protons on target every 16.8s, with 5·10¹⁹ protons accumulated over 5~years, place stringent demands on adequate muon sweeping to minimize backgrounds in the detector. The target and primary dump need to be able to survive these demanding conditions, while respecting strict radiation protection criteria. A series of design choices will be shown to lead to a neutral beamline sufficiently capable of suppressing relevant backgrounds, such as photons generated by pi0 decays in the target, and Lambda -> npi0 decays, which mimic the signal decay.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW061
About •	paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPGW071	Genetic Optimisation of Beamline Design for DIAMOND	synchrotron, framework, radiation, experiment	3753
	F. Bakkali Taheri, M. Apollonio, R. Bartolini, B. Singh DLS, Oxfordshire, United Kingdom R. Bartolini, J. Li JAI, Oxford, United Kingdom R. Bartolini Oxford University, Physics Department, Oxford, Oxon, United Kingdom
	The problem of optimisation of beamline structures is studied, from the point of view of multi-objective genetic algorithms. While this approach has been successfully used in the exploration of potential particle accelerator lattices, it has never been applied to beamline design. In this paper, the Non-Dominated Sorting Genetic Algorithm II (NGSA II) is used to optimize a structure where photons are assumed to propagate through the optical elements according to the wavefront model as implemented in SRW. It is shown that appropriate objective functions can help to set up an interesting set of parameters, with competitive computational resources compared to the traditional approach. Examples illustrating this optimization method are shown in the context of DIAMOND.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW071
About •	paper received ※ 13 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019
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THPRB033	Development Status of RF Reference Phase Stabilization System for SuperKEKB Injector LINAC	linac, controls, feedback, distributed	3879
	N. Liu, B. Du Sokendai - Hayama, Hayama, Japan D.A. Arakawa, H. Katagiri, T. Kobayashi, T. Matsumoto, S. Michizono, T. Miura, F. Qiu, Y. Yano KEK, Ibaraki, Japan T. Matsumoto, T. Miura, F. Qiu Sokendai, Ibaraki, Japan
	SuperKEKB injector linear accelerator (LINAC) has 600 m beam lines which consist of 8 sectors. The 2856 MHz RF reference signals are distributed to each sector with long phase stabilized optical fiber (PSOF). The RF reference phase stability requirement is estimated to be 0.2°(RMS) corresponding to 200 fs. The prototype of RF reference phase stabilization system with single mode optical circulator was implemented and demonstrated in the laboratory. The returned phase drift is compensated by a piezo-driven fiber stretcher. The transmitted phase through 120 m PSOF is stabilized to 41 fs (pk-pk), which fulfilled the requirement. This paper introduces the RF reference phase stabilization system and reports the preliminary feedback result.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB033
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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THPRB062	New Orbit Correction Method Based on SVDC Algorithm for Ring Based Light Sources	feedback, lattice, controls, simulation	3943
	X.Y. Huang, J.S. Cao, Y.Y. Du, Y.H. Lu, H.Z. Ma, Y.F. Ma, Y.F. Sui, S.J. Wei, Y. Wei, Q. Ye, X.E. Zhang, D.C. Zhu IHEP, Beijing, People’s Republic of China
	Funding: Union Foundation of excellent post-doctoral of China Orbit feedback system is essential for realizing the exceeding beam stability in modern ring based light sources. Most advanced light sources adopt the global correction scheme by using singular value decomposition (SVD) algorithm. In this paper, a new SVD with constraints method (SVDC) is proposed to correct the global and local orbit simultaneously. Numerical simulations are presented with the case of High Energy Light Source (HEPS) by comparing classic algorithms. The results show that SVDC is very effective for orbit correction and very easy to implement.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB062
About •	paper received ※ 09 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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THPRB090	Laboratory Exhaust Gas Treatment Systems at TPS	controls, synchrotron, status, experiment	4029
	J.-C. Chang, W.S. Chan, Z.-D. Tsai NSRRC, Hsinchu, Taiwan
	There are three main laboratory exhaust gas treatment systems equipped at Taiwan Photon Source (TPS): acid/alkaline system for corrosive acids and alkalis, volatile solvents, and other hazardous chemicals; organic system for biological experiments; and general system for other gas. Gas is collected in hoods installed near the sources of contamination in laboratories. The contamination then is transported through duct to the gas treatment equipment installed outside of the TPS experimental hall.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB090
About •	paper received ※ 06 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPRB091	APPLICATION PROGRAMS FOR TPS BEAM TRIP ANALYSIS	power-supply, kicker, electron, operation	4032
	B.Y. Chen, T.W. Hsu, B.Y. Huang, C.S. Huang, C.H. Kuo, T.Y. Lee, W.Y. Lin NSRRC, Hsinchu, Taiwan
	For the Taiwan Photon Source (TPS), the orbit inter-lock system is one of the most important machine pro-tection systems. It is the fastest and the most preferred system to detect abnormalities to prevent possible dam-ages caused by magnet power supply failures or subsys-tems failures. In order to monitor electron orbit changes during a beam trip, we developed the ’orbit monitoring and recording tool’, the ’TBT BPM analysis tool’ and the ’magnet power supply recording and analysis tool’ to assist us in the failure analysis as will be discussed in this paper.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB091
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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THPRB095	A Simulation Framework for Photon-Particle Interactions for Laserwires and Further Applications	laser, electron, scattering, simulation	4045
	S.E. Alden, S.M. Gibson, L.J. Nevay JAI, Egham, Surrey, United Kingdom
	A model has been developed for simulating photon-particle interactions with Beam Delivery Simulation (BDSIM). BDSIM is a high energy physics program that utilises the Geant4, CLHEP, and ROOT libraries to seamlessly track particles through an accelerator. The photon-particle interactions introduce the capability for modelling a range of applications in accelerator physics. One such application is a laserwire which is a minimally invasive diagnostic technique to measure beam profiles and emittance. In this paper we describe the recent implementation of inverse Compton scattering and electron stripping of Hydrogen ions. This is demonstrated on an example beamline.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB095
About •	paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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THPRB102	Monte Carlo Optimization of Fast Beam Loss Monitors for LCLS-II	detector, target, electron, simulation	4066
	M. Santana-Leitner, C.I. Clarke, A.S. Fisher, A.M. Harris, C. Hast, T.T. Liang SLAC, Menlo Park, California, USA E. Griesmayer CIVIDEC Instrumentation, Wien, Austria
	Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515 Commissioning of the LCLS-II hard X-ray FEL is starting at SLAC National Accelerator Laboratory. This facility will ultimately accelerate electrons to 8 GeV, with beams of 375 kW at 1 MHz. At such high-powers, errant beams will need to be detected very fast -200 μs- to limit exposure and to protect beam-line and safety components. Currently, LCLS-I uses ion chambers both as Point Beam Loss Monitors (PBLM) by collimators, dumps, septa, etc., and also as Long Beam Loss Monitors (LBML) that provide detection coverage in extended areas where the accelerator enclosure is not sufficiently thick to shield full beam losses. But due to the finite ion mobility and related screening effects, ion chambers are not fast enough, and their response would not be linear at high charge rates. LCLS-II will use synthetic mono-crystalline diamond chips as PBLMs, as those offer nanosecond time resolution due to the high mobility of holes generated in the valence band by charged particles. LBLMs will be 200 m-long optical fibers, with photomultipliers to detect Cerenkov photons produced by charged particles in the fibers. Use of these technologies requires tests and models to correlate their response to different beam losses. Response functions for these detectors have been developed for the FLUKA Monte Carlo code. After benchmarking the models, these have been applied to place PBLMs at locations where signal is relatively insensitive to beam-strike uncertainties and sufficiently above electronic noise, while keeping lifetime to radiation-damage long. Also, topologies where found were one PBLM can protect several components, resulting in cost reductions. As for LBLMs, the existing model helps scale signals for different beam loss configurations as a function of the fiber position.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB102
About •	paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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THPRB104	Improvements in Long-Term Orbit Stability at NSLS-II	feedback, operation, controls, storage-ring	4070
	Y. Hidaka, A. Caracappa, Y. Hu, B. Podobedov, R.M. Smith, Y. Tian, G.M. Wang BNL, Upton, Long Island, New York, USA
	Funding: The study is supported by U.S. DOE under Contract No. DE-SC0012704. We report our latest efforts to further improve long-term orbit stability at NSLS-II, on top of what is already provided by fast orbit feedback (FOFB) system. A DC local bump generation program, only utilizing RF beam position monitors (BPM) and compatible with FOFB, was first implemented and deployed in operation successfully, allowing on-demand fine adjustments of beamline source positions and angles. Then we introduced a simple feedback version that performs these bump corrections automatically as needed to maintain the sources within in 1 um/urad for select beamlines. In addition, an RF frequency feedback was also implemented to improve stability for 3-pole wigglers and bending magnet users. As a parallel effort, X-ray BPMs were included in a local feedback system to stabilize photon beam motion for several ID beamlines. However, this feedback scheme is not transparent to FOFB, and suspected to be the source of occasional saturation of fast corrector strength. As an alternative solution, the local bump program and its feedback version has been recently upgraded to include bumps with X-ray BPMs and in operation since April 2019.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB104
About •	paper received ※ 19 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPTS056	New Undulator and Front End for XAIRA Beamline at ALBA	undulator, vacuum, storage-ring, synchrotron	4231
	J. Campmany, J. Marcos, V. Massana ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
	A new microfocus beamline for macromolecular crystallography, XAIRA, is being built at ALBA synchrotron light source. The light source for this new beamline is an in-vacuum undulator that can reach the spectrum range from 4 keV up to 20 keV. The in-vacuum undulator was terndered in 2018 and awarded to Kyma-RI consortium, and will be delivered to ALBA in November 2019. The Front End has been designed accordingly. It was tendered in 2018 and awarded to FMB. It will be delivered along second semester of 2019. In this paper we present the ID and FE designs.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS056
About •	paper received ※ 11 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019
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THPTS064	Sub-Picosecond X-Ray Streak Camera using High-Gradient RF Cavities	electron, cathode, gun, simulation	4256
	F. Toufexis, V.A. Dolgashev SLAC, Menlo Park, California, USA
	Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515. We are developing an ultrafast diagnostic system for X-ray beams from Synchrotron Light Sources and Free-Electron Lasers. In this system, the X-ray beam is focused on the photocathode of a high-gradient radio-frequency cavity that accelerates the photo-emitted electrons to a few MeV while preserving their time structure. The accelerated electron beam is streaked by radio-frequency deflectors and then imaged on a screen. This approach will allow orders of magnitude improvement in time resolution over traditional streak cameras and could potentially enable time-resolved diagnostics of sub-100 fs X-ray pulses. We present preliminary beam dynamics simulations of this system and discuss the implementation.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS064
About •	paper received ※ 11 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019
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Paper

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MOPGW053

Residual Gas Lifetime In High Energy Photon Source (HEPS)

scattering, electron, dynamic-aperture, vacuum

210

S.K. Tian, H.S. Xu
IHEP, Beijing, People’s Republic of China

High vacuum has always been mandatory in particle accelerators. This is especially true for circular machines, where the beam makes thousands or millions turns, and beam lifetime is heavily affected by the residual gas scattering. At the beginning of storage ring operation the lifetime was very short mostly dominated by residual gas scattering. The residual gas lifetime is comprised of the elastic and inelastic scattering on electrons and elastic and inelastic scattering on nuclei. One usually calculates only the elastic scattering on nuclei (single Coulomb scattering) and inelastic scattering on nuclei (bremsstrahlung) of the residual gas scattering lifetime component. The analytic calculation the residual gas scattering lifetime and simulations of the beam interaction with the residual gas with code will be shown in this presentation

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paper received ※ 15 May 2019 paper accepted ※ 19 May 2019 issue date ※ 21 June 2019

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MOPMP035

Effect of Emittance Constraints on Monochromatization at the Future Circular e⁺e⁻ Collider

emittance, luminosity, collider, radiation

516

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

Direct s-channel Higgs production in e+e− collisions is of interest if the collision energy spread can be comparable to the natural width of the standard model Higgs boson. At the Future Circular e⁺e⁻ Collider (FCC-ee), a monochromatization scheme could be employed in order to reduce the collision energy spread to the target value. This may be achieved by introducing a non-zero horizontal dispersion of opposite sign for the two colliding beams at the interaction point. In this case, the beamstrahlung increases the horizontal emittance in addition to energy spread and bunch length. The vertical emittance could either be tuned to a certain minimum value, possibly limited by the diagnostics resolution, or it could scale linearly with the horizontal emittance. For the FCC-ee at 62.5 GeV beam energy, we optimize the IP optics and beam parameters, considering these two different assumptions for the vertical emittance. We derive the maximum achievable luminosity as a function of collision energy spread for either case.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPMP035

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paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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MOPRB024

Beam-Gas and Beam-Thermal Photon Scattering in CEPC

scattering, background, detector, factory

626

S. Bai, J. Gao, H. Geng, D. Wang, Y. Wang, C.H. Yu, Y. Zhang
IHEP, Beijing, People’s Republic of China
Y. Zhang
University of Chinese Academy of Sciences, Beijing, People’s Republic of China

The Circular Electron Positron Collider (CEPC) is a proposed Higgs factory with center of mass energy of 240 GeV to measure the properties of Higgs boson and test the standard model accurately. Beam loss background in detectors is an important topic at CEPC. Beam-Gas scattering (BG) and Beam-Thermal photon scattering (BTH), although not so serious as Radiative Bhabha scattering (RBB) and Beamstrahlung (BS), are also important components of the beam induced backgrounds at CEPC due to the beam lifetime. In this paper, we evaluated the beam-gas and beam-thermal photon scattering in simulation and designed collimators to suppress the radiation level on the machine and the detector.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB024

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paper received ※ 28 April 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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MOPRB052

Gamma Factory at CERN: Design of a Proof-of-Principle Experiment

laser, experiment, electron, cavity

685

Y. Dutheil, R. Alemany-Fernández, H. Bartosik, N. Biancacci, R. Bruce, P. Czodrowski, V. Fedosseev, B. Goddard, S. Hirlaender, J.M. Jowett, R. Kersevan, M. Kowalska, M. Lamont, D. Manglunki, J. Molson, A.V. Petrenko, M. Schaumann, F. Zimmermann
CERN, Geneva, Switzerland
S.E. Alden, A. Bosco, S.M. Gibson, L.J. Nevay
JAI, Egham, Surrey, United Kingdom
A. Apyan
ANSL, Yerevan, Armenia
E.G. Bessonov
LPI, Moscow, Russia
A. Bosco, S.M. Gibson, L.J. Nevay
Royal Holloway, University of London, Surrey, United Kingdom
F. Castelli
Università degli Studi di Milano, Milano, Italy
F. Castelli, C. Curatolo, L. Serafini
INFN-Milano, Milano, Italy
K. Kroeger
FSU Jena, Jena, Germany
A. Martens
LAL, Orsay, France
V. Petrillo
Universita’ degli Studi di Milano, Milano, Italy
M. Sapinski, T. Stöhlker
GSI, Darmstadt, Germany
G. Weber
IOQ, Jena, Germany
Y.K. Wu
FEL/Duke University, Durham, North Carolina, USA

The Gamma Factory (GF) initiative proposes to create novel research tools at CERN by producing, accelerating and storing highly relativistic partially stripped ion beams in the LHC rings and by exciting their atomic degrees of freedom by lasers, to produce high-energy photon beams. Their intensity would be several orders of magnitude higher than those of the presently operating light sources in the particularly interesting gamma-ray energy domain reaching up to 400 MeV. In this energy domain, the high-intensity photon beams can be used to produce secondary beams of polarized electrons, polarized positrons, polarized muons, neutrinos, neutrons and radioactive ions. Over the years 2017-2018 we have demonstrated that these partially stripped ion beams can be successfully produced, accelerated and stored in the CERN accelerator complex, including the LHC. The next step of the project is to build a proof of principle experiment in the SPS to validate the principal GF concepts. This contribution will present the initial conceptual design of this experiment along with its main challenge - the demonstration of the fast cooling method of partially stripped ion beams.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-MOPRB052

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MOPRB056

THz Radiator Based on Photonic Band Gap Crystal for SwissFEL

electron, GUI, experiment, FEL

693

L. Shi, R. Ischebeck, S. Reiche
PSI, Villigen PSI, Switzerland

Funding: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 701647.
The electromagnetic radiation in 1-20 THz has many unique properties when it interacts with matter due to its non-ionizing excitation in matter. Especially the dynamics of the excited matter can be probed with the help of X-ray pulses at a free electron laser facility, e.g. SwissFEL, to deepen our understanding of a wide range of phenomena. Due to its high research potential, various means of THz generation have been proposed and demonstrated. We investigate preliminarily here its generation based on a relativistic electron bunch and a photonic band gap crystal (PBG) made of dielectric rods. The PBG provides additional degrees of freedom for the THz pulse tuning. Additionally, the unwanted radiation parts can be damped by the structure in order to minimize the deleterious beam dynamics effects. The crystal also promises the integration of generation, filtering and coupling for transport into a single piece.

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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MOPRB088

Study of Fluctuations in Undulator Radiation in the IOTA Ring at Fermilab

experiment, undulator, electron, radiation

777

I. Lobach
University of Chicago, Chicago, Illinois, USA
A. Halavanau, Z. Huang, V. Yakimenko
SLAC, Menlo Park, California, USA
K. Kim
ANL, Argonne, Illinois, USA
V.A. Lebedev, S. Nagaitsev, A.L. Romanov, G. Stancari, A. Valishev
Fermilab, Batavia, Illinois, USA
A.Y. Murokh
RadiaBeam, Los Angeles, California, USA
T.V. Shaftan
BNL, Upton, Long Island, New York, USA

We study turn-by-turn fluctuations in the number of emitted photons in an undulator, installed in the IOTA electron storage ring at Fermilab with an InGaAs PIN photodiode and an integrating circuit. Our study was motivated by the previous experiment *. We propose a theoretical model for the experimental data from * and in our own experiment we attempted to verify the model in an independent and more systematic way. Moreover, these fluctuations are an interesting subject for a study by itself, since they act as a seed for SASE in FELs. We improve the precision of the measurements from * by subtracting the average signal amplitude using a comb filter with a one-turn IOTA delay, and by using a special algorithm for noise subtraction. We obtain a reasonable agreement between our theoretical model and experiment. Along with repeating the experiment from *, which was performed at a constant beam current, we also collect data for fluctuations in undulator light at different beam current values. Lastly, in our experiment we were able to see the transition from Poisson statistics to Super-Poisson statistics for undulator light, whereas in * only the latter statistics was observed.
* M. Teich et al., PRL, vol. 65, no. 27, p. 3393 (1990).

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MOPRB089

Experimental Study of a Single Electron in a Storage Ring via Undulator Radiation

electron, undulator, experiment, radiation

781

S. Nagaitsev, A.L. Romanov, G. Stancari
Fermilab, Batavia, Illinois, USA
A. Arodzero, A.Y. Murokh, M. Ruelas
RadiaBeam, Santa Monica, California, USA
I. Lobach
University of Chicago, Chicago, Illinois, USA
T.V. Shaftan
BNL, Upton, Long Island, New York, USA

A single electron orbiting around a ring and emitting single quanta at the rate of about one event per hundred turns could produce a wealth of information about physical processes in large traps (i.e. storage rings) for charged particles. It should be noted that Paul and Penning traps in the 1980s led to the Nobel prize for studying state and motion of single quantum particles, and just recently the Penning trap technique has enabled the measurement of a single proton magnetic moment with an unprecedented precision of 10 decimal places. The information from the storage ring traps could also be used for characterization of a quantum system as well as the "trap" itself, i.e. measuring properties of the storage ring lattice and electron interaction with the laser fields. Although, the interest in single electron quantum processes today is mostly academic in nature, the diagnostics and methodology developed for single electron radiation studies could find subsequent applications in a variety of applied disciplines in quantum technology, including quantum communications and quantum computing.

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TUYPLM1

XFEL Performance Achieved at PAL-XFEL

FEL, undulator, electron, emittance

1182

H. Heo, M.-H. Cho, J.H. Han, H.-S. Kang, C. Kim, G. Kim, M.J. Kim, J.H. Ko, H.-S. Lee, C.-K. Min, I.H. Nam, K.-H. Park, C.H. Shim, H. Yang
PAL, Pohang, Kyungbuk, Republic of Korea

The hard X-ray free electron laser at Pohang Accelerator Laboratory (PAL-XFEL) successfully completed the commissioning of SASE and started user operation in late 2016. Since then, the facility has demonstrated excellent stability with very small timing jitter of about 20 fs, and commissioned the self-seeding system over a wide range of photon energies, etc. The talk will provide an overview of the last three years at the PAL-XFEL, including some detailed experimental results, as well as future prospects for the laboratory.

Slides TUYPLM1 [7.516 MB]

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TUZPLS2

Beam Dynamics Study in the HEPS Storage Ring

lattice, storage-ring, emittance, brightness

1203

Y. Jiao, X. Cui, Z. Duan, Y.Y. Guo, P. He, X.Y. Huang, D. Ji, H.F. Ji, C. Li, J.Y. Li, X.Y. Li, C. Meng, Y.M. Peng, Q. Qin, S.K. Tian, J.Q. Wang, N. Wang, Y. Wei, G. Xu, H.S. Xu, F. Yan, C.H. Yu, Y.L. Zhao
IHEP, Beijing, People’s Republic of China

The High Energy Photon Source (HEPS) is the first high-energy diffraction-limited storage ring (DLSR) light source to be built in China, with a natural emittance of a few tens of pm rad and a circumference of 1360.4 m. After 10 years’ evolution, the accelerator physics design of the HEPS has been basically determined, with the ring consisting of 48 hybrid-7BAs with anti-bends and super-bends. This paper will discuss the accelerator physics studies of the HEPS storage ring, covering issues of lattice design, nonlinear optimization, collective effects, error correction, insertion devices, etc.

Slides TUZPLS2 [9.517 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUZPLS2

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPMP007

DYVACS (DYnamic VACuum Simulation) Code: Calculation of Gas Density Profiles in Presence of Electron Cloud

electron, vacuum, proton, experiment

1244

G. Sattonnay, S. Bilgen, B. Mercier
LAL, Orsay, France
V. Baglin
CERN, Meyrin, Switzerland

The computation of residual gas density profiles in particle accelerators is an essential task to optimize beam pipes and vacuum system design. In a hadron collider such as the LHC, the beam induces dynamic effects due to ion, electron and photon-stimulated gas desorption. The well-known VASCO* code developed at CERN in 2004 (and then PyVASCO**) is already used to estimate vacuum stability and density profiles in steady state conditions. Nevertheless, some phenomena are not taken into account such as the ionization of residual gas by the electron clouds. Therefore, we propose an upgrade of this code by introducing electron cloud maps*** to estimate the electron density and the ionization of gas by electrons, leading to an increase of both electron- and ion-induced desorption. Results obtained with the new code (called DYVACS for DYnamic VACuum Simulation) will be compared to pressure measurements in the VPS sector**** of the LHC.
* A. Rossi, Tech. Rep., LHC Proj. Note 341
** I. Aichinger, et al arXiv:1707.07525
*** T. Demma et al Phys. Rev. Acceler. and Beams 10, 114401 (2007)
**** B. Henrist et al, Proc. IPAC2014, Dresden

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP007

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPMP018

Feasibility Tests of a Vacuum System for SPring-8-II

vacuum, hardware, multipole, operation

1272

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

For SPring-8-II, the major upgrade of SPring-8, a test half-cell including permanent/electro magnets and a vacuum system was constructed, and hardware feasibility tests have been performed since 2017. Features of the SPring-8-II vacuum system are 1) introduction of the concept of a stainless steel 12 m-long integral chamber (LIC) with a welded structure, and 2) adoption of ex-situ baking of the chamber. The 12 m LIC with a narrow aperture, flangeless structure and a minimum number of bellows was designed so that the vacuum system could be installed without interference with the magnets of a narrow bore diameter aligned on girders with a severe packing factor. For replacement of the existing system with a new one in a short black-out period, the 12 m LIC is planned to be moved into the accelerator tunnel with keeping ultra-high vacuum (UHV) by closing thin gate valves at both ends, after evacuation to UHV by ex-situ baking and NEG activation. This presentation will overview the vacuum system, mainly the 12 m LIC, developed for the test half-cell, and describe the vacuum performance and the result of the assembly test conducted with the permanent/electro magnets.

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paper received ※ 15 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019

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TUPMP019

Vacuum Performance of the NEG-coated Chamber for U#19 at PF-ring

vacuum, simulation, MMI, undulator

1276

Y. Tanimoto, T. Honda, X.J. Jin, T. Nogami, R. Takai, M. Yamamoto
KEK, Ibaraki, Japan

At the Photon Factory storage ring (PF-ring) in KEK, a new APPLE-II type elliptically polarizing undulator (U#19) was installed in October 2018. The U#19 vacuum chamber is 4.1 meters in length, and the beam channel with a 15x90 elliptical profile and two cooling-water channels alongside were formed by extrusion of A6060-T6 aluminum alloy. The inner surface of the beam channel is coated with a Ti-Zr-V Non-Evaporable Getter (NEG) thin film, as it has a high effective pumping speed and a low Photon Stimulated Desorption (PSD) yield. After the installation of the U#19, the neighboring uncoated chambers and vacuum components were baked out at 200 °C for 44 hours, and then the NEG coating was activated at 160 °C for 48 hours. As a result, the pressures in the neighboring chambers reached as low as 10^-8 Pa. The conditioning of the vacuum chambers with irradiation of Synchrotron radiation evolved favorably as had been expected by a combined simulation of Synrad and Molflow, leading to a satisfactory recovery of the beam lifetime. Vacuum performance of the NEG-coated chamber was assessed especially by means of a residual gas analysis, and the properties of the NEG film were characterized by surface analyses including SEM, EDX, and XRD.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPMP019

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paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPMP035

Design of the Vacuum System of the FCC-ee Electron-Positron Collider

collider, vacuum, dipole, quadrupole

1319

R. Kersevan, C. Garion
CERN, Geneva, Switzerland

The Future Circular Collider (FCC) Design Study includes the twin storage ring (FCC-ee) where electrons and positrons are stored and made to collide inside two detectors. The vacuum system of FCC-ee must be designed in order to deal with a lower-energy (45.6 GeV), high-current (1390 mA) Z-pole machine and at a later stage with a higher-energy (182.5 GeV) low-current (5.4 mA). The former machine is the most challenging one from the point of view of vacuum, since the photon-stimulated desorption (PSD) generated by the copious synchrotron radiation (SR) fans is quite large. While several concepts have been considered at the beginning, the design retained for the Conceptual Design Report (CDR) is one where the cross-section of the vacuum chamber (VC) in the arcs is a scaled-down version of the one implemented in the SUPERKEKB collider. Contrary to SUPERKEKB tough, the SR fans are absorbed by many short absorbers, with average spacing of 5.8 m. This allow a localization of the PSD gas load and to place lumped pumps in front of the SR absorbers, to maximize the pumping efficiency. The VC design is compatible with the design of the common-yoke dipoles and quadrupoles. The VC material is copper alloy. Optimization of the pressure profiles has been carried out by means of extensive coupled montecarlo simulations, for SR and molecular flow. For the higher energy versions of the machine, for which the SR spectra are characterized by critical energies well above the Compton edge, the localized absorbers facilitate also shielding the tunnel and any radiation-sensitive machine components from X-ray photon damage, by installing short high-Z material around the absorbers. The major features of the CDR relevant for vacuum will be highlighted in the paper.

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paper received ※ 13 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPMP036

Results on the FCC-hh Beam Screen Sawtooth at the Kit Electron Storage Ring Kararesults on the Fcc-Hh Beam Screen Sawtooth at the Kit Electron Storage Ring Kara

radiation, vacuum, experiment, electron

1323

L.A. Gonzalez, V. Baglin, I. Bellafont, P. Chiggiato, C. Garion, R. Kersevan
CERN, Geneva, Switzerland
I. Bellafont, F. Pérez
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
S. Casalbuoni, E. Huttel
KIT, Eggenstein-Leopoldshafen, Germany

Funding: * The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 654305.
In the framework of the EuroCirCol collaboration (work package 4 "Cryogenic Beam Vacuum System"), the fabrication of the FCC-hh beam screen (BS) prototype has been carried out with the aim of testing it at room temperature on the Karlsruhe Institute of Technology (KIT) 2.5 GeV electron storage ring KARA (KArlsruhe Research Accelerator) light source. The BS prototype was tested on a beamline installed by the collaboration, named as BEam Screen TEstbench EXperiment (BESTEX). KARA has been chosen because its synchrotron radiation (SR) spectrum, photon flux and power match quite well the one foreseen for the 50+50 TeV FCC-hh proton collider. The BS prototype (2 m in length) was manufactured according to the base line design (BD) of the FCC-hh BS. It implements a saw-tooth profile designed to absorb the SR generated at the bending magnets. Also, a laser-ablated anti-electron cloud surface texturing [2] was applied at the BS inner walls. We present here the results obtained at BESTEX and the comparison of the results obtained during irradiation of the saw-tooth profile at different geometric configurations.
This activity has been carried out in the framework of the EuroCirCol* collaboration (work package 4 "Cryogenic Beam Vacuum System").

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TUPMP037

Recent Developments of Monte-Carlo Codes Molflow+ and Synrad+

simulation, vacuum, synchrotron, synchrotron-radiation

1327

R. Kersevan, M. Ady
CERN, Geneva, Switzerland

Molflow+ and Synrad+ are Monte Carlo simulation tools for ultra-high vacuum and synchrotron radiation, respectively. Over the years they have become a common tool for designing and analysing the vacuum system of particle accelerators. This contribution gives a short summary about new features added since IPAC-14*. Some highlights: In traditional Monte Carlo simulations, one simulated ’virtual’ particle represents a given number of physical molecules or photons. This is a weakness where the pressure or flux of the simulated system spans across multiple orders of magnitude. Synrad now supports low flux mode, a weighed Monte Carlo technique where the represented number of photons is reduced at every reflection, providing significantly better statistics at low flux regions. As for Molflow+, angle maps allow recording the molecules, directional distribution at any point, and then desorb a reduced gas quantity according to the recording. In linear systems, this allows iterative simulations that have been proven to treat systems up to 7 orders of magnitude of pressure difference. Without the new technique the computing time would be prohibitively slow on desktop computers, which is what most users of the two codes use. Both codes now have a built-in geometry builder that allows creating simple models through a set of 3D operations, and modifying those imported from CAD tools. Molflow+ has recently become open source, and it has been made compatible with, and tested on different versions of Linux and macOS. Examples of application of Molflow+ to novel Beam Gas Curtain detector and the design of the FCC-ee vacuum system will be given, alongside with some benchmarking runs against data published in literature.
* M. Ady, R. Kersevan, "Introduction to the Latest Version of the Test-particle Monte Carlo Code Molflow+", Proc. IPAC’14, Dresden, Germany, June 2014, pp. 2348-2350.

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TUPMP038

Summary of Modelling Studies on the Beam Induced Vacuum Effects in the FCC-hh

vacuum, electron, collider, synchrotron

1331

I. Bellafont, R. Kersevan, L. Mether
CERN, Geneva, Switzerland

Funding: The European Circular Energy-Frontier Collider Study (EuroCirCol) project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant No 654305.
EuroCirCol is a conceptual design study of a Future Circular Collider (FCC-hh) which aims to expand the current energy and luminosity frontiers that the LHC has established. The vacuum chamber of this 50 TeV, 100 km collider, will have to cope with unprecedented levels of synchrotron radiation power for proton colliders, dealing simultaneously with a tighter magnet aperture. Since the high radiation power and photon flux will release large amounts of gas into the system, the difficulty to keep a low level of residual gas density increases considerably compared with the LHC. This article presents a study of the beam induced vacuum effects for the FCC-hh novel conditions, the different phenomena which, owing to the presence of the beam, have an impact on the vacuum level of the accelerator. To achieve this, a novel beam screen has been proposed, featuring specific mitigating measures aimed at dealing with the beam induced effects. It is concluded that thanks to the new beam screen design, the vacuum level in the FCC-hh shall be adequate, allowing to reach the molecular density requirement of better than 10¹⁵ H₂/m3 with baseline beam parameters within the first months of conditioning.

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paper received ※ 10 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPMP044

Special Aluminum Gasket Sealing of Non-circular Profile Flanges for the Accelerator UHV Systems

vacuum, impedance, experiment, emittance

1347

G.Y. Hsiung
NSRRC, Hsinchu, Taiwan

Most of the beam ducts for the accelerators are not regularly the circular profile. Unfortunately, the conflat (CF-) flanges and the gaskets with non-circular profile were not commercially available. Besides, additional RF-contact bridges between the flanges must be built in for mitigating the impedance from the flange-gaps. In this presentation, various types of the aluminum (Al-) gaskets designed for the non-circular profile Al-flanges for the accelerator ultrahigh vacuum (UHV) systems are introduced. The surface of the Al-flange is flat to accommodate the special Al-gasket with knife edges for the sealing. Both the flange and gasket are manufactured by the oil-free Ethanol-CNC-machining process that any non-circular profile, e.g. rectangular, race-track, key-hole, etc., flanges can be precisely produced. The inner diameters of the gasket just suits those of the flanges that the impedance from the gap is significantly reduced. The flanges and gaskets after oil-free machining can be assembled immediately without any chemical cleaning. The experimental results for the as-mentioned non-circular profile Al-flanges reveal the UHV quality at pressure < 20 nPa after vacuum baking.

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPMP046

Improvement the Bending Magnet Power Supply Performance for TPS Storage Ring

power-supply, storage-ring, feedback, controls

1353

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

In the TPS (Taiwan Photon Source) facility, current stability of the electron beam depends on the bending magnet power supply and an orbit FOFB system to compensate the magnetic field. Due to the output current stability of the bending magnet power supply drifts with temperature so the orbit FOFB system should be applied to fine tune magnetic field and the photon beam should circulate in storage ring. In this paper, to stabilize the temperature of regulation circuit’s temperature box of the bending magnet power supply, the long-term output current stability is improve from ± 50ppm to ± 10ppm, and orbit FOFB system substantially reduce the tune X of beam position, effectively increasing the beam current stability and quality.

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paper received ※ 12 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPMP050

Conceptual Design of the Diamond-II Vacuum System

vacuum, storage-ring, target, controls

1362

M.P. Cox, C. Burrows, A.G. Day, J.A. Dymoke-Bradshaw, R.K. Grant, N.P. Hammond, X. Liu, A.G. Miller, H.S. Shiers, N. Warner
DLS, Oxfordshire, United Kingdom

The conceptual design of the vacuum system for the Diamond-II storage ring upgrade is described. Due to the small vessel cross section, typically 20 mm inside diameter (ID), and the consequent conductance limitation, distributed pumping is provided by non-evaporable getter (NEG) coating supplemented by ion pumps at high gas load locations. In-situ bakeout is incorporated to allow rapid recovery from both planned vacuum interventions and unplanned vacuum events. The vacuum vessels are constructed mainly from copper alloy while stainless steel is used in regions of AC magnets requiring low electrical conductivity. The proposed layout, engineering and build sequence of the vacuum system are described along with gas flow simulations confirming the vacuum performance advantages of NEG-coated vessels compared with uncoated vessels.

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPGW013

Tune and Chromaticity Optimization at Bessy II for the Transverse Resonant Island Bucket Optics

optics, simulation, resonance, emittance

1411

F. Armborst, P. Goslawski, A. Jankowiak
HZB, Berlin, Germany

Funding: Federal Ministry of Education and Research
Transverse Resonant Island Buckets (TRIBs *) correspond to a second stable orbit, longitudinally winding around the core orbit in the transverse x-x^′-phasespace. The exploitation possibilities for stable TRIBs are under investigation at the third generation light source BESSY II in Berlin. The applicability for bunch separation is a main subject of these studies. Stable operation of TRIBs optics with a single or few bunches on the second orbit and a multibunch train on the main orbit has been shown **. Photons emitted on the second orbit are well separated from those of the main orbit at all beamlines. This provides the possibility of bunch separation by beamline adjustment for the timing community without significant impact on the average brightness for other users. Simulations based on linear optics from closed orbits (LOCO) and on nonlinear optics derived from the measured chromaticity and tune shift with action (TSWA) predict this separation well. Friendly user experiments in 2018 confirmed these results. The scheduled upgrade BESSY VSR *** features simultaneously stored long and short bunches. Then TRIBs optics would in principle enable the separation of the different bunches at every beamline offering unique possibilities to our users. Simulations and measurements aiming to investigate further possible optimization of the TRIBs optics are presented.
* F. Armborst, P. Goslawski et al, DOI: 10.18429/JACoW-IPAC2018-TUPML052
** P. Goslawski, F. Armborst et al. DOI: 10.18429/JACoW-IPAC2017-WEPIK057
*** A. Jankowiak et al., DOI: 10.5442/R0001

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paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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TUPGW046

Progress of Lattice Design and Physics Studies on the High Energy Photon Source

lattice, storage-ring, booster, injection

1510

Y. Jiao, X. Cui, Z. Duan, Y.Y. Guo, P. He, X.Y. Huang, D. Ji, C. Li, J.Y. Li, X.Y. Li, C. Meng, Y.M. Peng, Q. Qin, S.K. Tian, J.Q. Wang, N. Wang, Y. Wei, G. Xu, H.S. Xu, F. Yan, C.H. Yu, Y.L. Zhao
IHEP, Beijing, People’s Republic of China

The High Energy Photon Source (HEPS) is an ul-tralow-emittance, kilometer-scale storage ring light source to be built in China. In this paper we will introduce the progress of the physics design and related studies of HEPS over the past year, covering issues in storage ring lattice design, injection and injector design, insertion device effects, error study and lattice calibration, collective effects, etc.

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPGW085

A Hard X-Ray Compact Compton Source at CBETA

electron, laser, scattering, brilliance

1604

K.E. Deitrick, C. Franck, G.H. Hoffstaetter, V.O. Kostroun, K.W. Smolenski
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
J. Crone, H.L. Owen
UMAN, Manchester, United Kingdom
B.D. Muratori
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom

Compton backscattering at energy recovery linacs (ERLs) promises high flux, high energy x-ray sources in the future, made possible by high quality, high repetition rate electron beams produced by ERLs. CBETA, the Cornell-BNL ERL Test Accelerator currently being built and commissioned at Cornell, is an SRF multi-turn ERL using Non-Scaling Fixed Field Alternating-gradient (NS-FFA) arcs. CBETA has high quality design parameters with an anticipated top energy of 150 MeV on the fourth pass. The expected parameters of a Compton source at CBETA include a top x-ray energy of over 400 keV with a flux on the order of 10¹² ph/s. In this paper, we present anticipated parameters and potential applications in science and engineering for this source.

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPGW106

Present Status of the PF-ring and PF-AR Operations

operation, injection, undulator, ECR

1654

R. Takai, T. Honda, Y. Kobayashi, S. Nagahashi
KEK, Ibaraki, Japan

The Photon Factory at KEK has been managing two synchrotron radiation sources, the PF-ring and PF-AR, for over 30 years. Although their operation time has been decreasing in recent years for budget reasons, continuous efforts to improve their performance have been made. In this paper, the operational status of these light sources for FY2018 is described. At the PF-ring, a first-generation undulator was renewed with the beamline components. A vacuum chamber for the new undulator was applied the NEG coating on the inner surface. This is the first attempt in Japanese light sources that the NEG-coated chamber is used for undulators. At the PF-AR, the top-up injection using the direct beam transport line was introduced to the user operation for the first time. Since modification of the beam injector LINAC for enabling simultaneous injection to the four different rings (the PF-ring, PF-AR, SuperKEKB HER and LER) was completed, this top-up operation no longer disturbs the operation of the other three rings. A low-energy operation of the PF-AR was also tested to secure more operation time within the limited budget.

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPGW109

Conceptual Design of Vacuum Chamber for SPS-II Storage Ring

vacuum, storage-ring, impedance, emittance

1666

T. Phimsen, S. Chaichuay, N. Juntong, P. Klysubun, S. Prawanta, P. Sudmuang, P. Sunwong
SLRI, Nakhon Ratchasima, Thailand
R. Deepan, A. Khamkham
Suranaree University of Technology, Nakhon Ratchasima, Thailand

The SPS-II is a 3 GeV ultralow emittance light source which is now under studied and designed by Thailand Synchrotron Light Research Institute (SLRI). The SPS-II storage ring is based on Double-Triple Bend Achromat (DTBA) cell with a circumference of 321.3 m aiming for horizontal emittance of less than 1 nm-rad. The compact lattice leaves narrow space for vacuum components. The small gap between poles of the magnets requires narrow vacuum chambers and limits the conductance of the chambers. The chambers will be made by stainless steel with a thickness of 1.5 mm. the cross section of beam duct is 40 mm × 16 mm elliptical shape. The bending chamber is designed as a long triangular chamber such that photon absorber can be installed as far from the light source as possible to lower the power density of the heat load. The overview of designed vacuum system for the SPS-II is presented.

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TUPRB002

The Conceptual Design of a 36 GHz RF Undulator

undulator, cavity, electron, GUI

1676

D. Zhu
ASCo, Clayton, Victoria, Australia
A.W. Cross, L. Zhang
USTRAT/SUPA, Glasgow, United Kingdom
Y.E. Tan
AS - ANSTO, Clayton, Australia

The CompactLight project supported by European H₂020 is to design a hard X-ray FEL facility beyond today’s state of the art. The project integrates photo injector, X-band acceleration and innovative compact short-period undulators together to make the machine more compact. RF undulator has an extraordinary advantage of working at very short undulator period. A conceptual design for a RF undulator at 36 GHz using a corrugated cylindrical waveguide operating in the HE11 mode is presented in this paper. Based on beam dynamics simulation and photon beam radiation simulations, the possibility of RF undulator to be used in CompactLight project is evaluated.

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TUPRB005

Photon Polarisation Modelling of APPLE-II EPUs

polarization, undulator, operation, simulation

1687

M.J. Sigrist, C.K. Baribeau, T.M. Pedersen
CLS, Saskatoon, Saskatchewan, Canada

The CLS is currently commissioning two APPLE-II in-sertion devices (IDs), see [1], and constructing two more that allow for operation in ’universal mode’, i.e. selecting arbitrary photon polarisation parameters. Two of these devices will operate in the soft x-ray range where there is expected to be a significant change to polarisation at the sample due to transmission effects of the beam line op-tics. Arbitrary polarisation selection of the ID will counter transmission effects and enable circular polarisation at the sample position. A polarisation model of the device is derived which allows for the calculation of both the Stokes parameters and photon energy for any set point of ID gap and phase. Numerical solutions of these equa-tions allow the calculation of gap and phase set points for any desired photon energy or polarisation. The results of the polarisation model are compared with numerical simulations of the synchrotron radiation calculated using measured magnetic fields at various polarisation modes.

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TUPRB008

LUXE - a QED Experiment at the European XFEL

experiment, FEL, electron, laser

1694

F. Burkart, R.W. Aßmann, R. Brinkmann, W. Decking, N. Golubeva, B. Heinemann, M. Hüning, J. List, M. Wing
DESY, Hamburg, Germany
M. Wing
UCL, London, United Kingdom

The proposed experiment aims to measure QED in the presence of strong fields and above the Schwinger critical field. An experiment is being considered at the European XFEL, which should be able to measure non-perturbative QED and its transition from the perturbative regime. This paper presents the current status of the LUXE (Laser und XFEL Experiment) design study. First layout considerations; accelerator beam line design, electron and laser beam parameters, radioprotection issues and first results of the start to end simulations will be presented and discussed in detail. An outlook concerning the implementation into the XFEL schedule and timeline of this experiment will be given.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB008

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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TUPRB020

Status of the European XFEL

FEL, operation, electron, MMI

1721

W. Decking, F. Brinker, L. Fröhlich, R. Kammering, T. Limberg, S. Liu, D. Nölle, M. Omet, M. Scholz, T. Wamsat
DESY, Hamburg, Germany

The European XFEL is a Hard X-ray Free Electron Laser based on superconducting accelerator technology. In operation since 2017, it now serves 3 FEL beamlines simultaneously for user experiments. We will report on the present operation of the linear accelerator, the beam distribution to the various beamlines and the performance of the FEL radiators.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB020

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paper received ※ 15 May 2019 paper accepted ※ 17 May 2019 issue date ※ 21 June 2019

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TUPRB022

Triple Period Undulator

undulator, radiation, vacuum, operation

1728

A. Meseck, J. Bahrdt, W. Frentrup, M. Huck, C. Kuhn, C. Rethfeldt, M. Scheer
HZB, Berlin, Germany
E.C.M. Rial
DLS, Oxfordshire, United Kingdom

Insertion devices are one of the key components of modern synchrotron radiation facilities. They allow for generation of radiation with superior properties enabling experiments in a variety of disciplines, such as chemistry, biology, crystallography and physics to name a few. For future cutting edge experiments in soft and tender x-rays users require high flux and variable Polarization over a wide photon energy range independent of other desired properties like variable pulse length, variable timing or Fourier transform limited pulses. In this paper, we propose a novel ID-structure, called Triple Period Undulator (TPU), which allow us to deliver a wide energy range from a few ten eV to a few keV at the same beamline with high flux and variable Polarization. The TPU are particularly interesting in context of BESSY III, the successor facility of BESSY II.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB022

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paper received ※ 15 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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TUPRB023

Considerations for the Ultrahard X-ray Undulator Line of the European XFEL

undulator, FEL, electron, operation

1732

E. Schneidmiller, V. Balandin, W. Decking, M. Dohlus, N. Golubeva, D. Nölle, M.V. Yurkov, I. Zagorodnov
DESY, Hamburg, Germany
G. Geloni, Y. Li, S. Molodtsov, J. Pflüger, S. Serkez, H. Sinn, T. Tanikawa, S. Tomin
EuXFEL, Schenefeld, Germany

The European XFEL is a multi-user X-ray FEL facility based on superconducting linear accelerator. Presently, three undulators (SASE1, SASE2, SASE3) routinely deliver high-brightness soft- and hard- X-ray beams for users. There are two empty undulator tunnels that were originally designed to operate with spontaneous radiators in the range 20-90 keV. We consider, instead a possible installation of two FEL undulators. One of them (SASE4) is proposed for operation in a standard (7-25 keV) range as well as in ultrahard (25-100 keV) regime. We discuss a possible location and length of SASE4, modifications of electron beam transport, beam dynamics, choice of undulator technology, different operation modes (SASE and advanced lasing concepts) etc.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB023

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB025

Harmonic Lasing of the European XFEL in the Angstrom Regime

FEL, undulator, experiment, operation

1740

E. Schneidmiller, F. Brinker, W. Decking, D. Nölle, M.V. Yurkov, I. Zagorodnov
DESY, Hamburg, Germany
N. Gerasimova, J. Grünert, N.G. Kujala, J. Laksman, Y. Li, J. Liu, Th. Maltezopoulos, I. Petrov, L. Samoylova, S. Serkez, H. Sinn, F. Wolff-Fabris
EuXFEL, Hamburg, Germany

Harmonic lasing in XFELs is an opportunity to extend the photon energy range of existing and planned X-ray FEL user facilities. Contrary to nonlinear harmonic generation, harmonic lasing can provide much more intense, stable, and narrow-band FEL beam. Another interesting application is Harmonic Lasing Self-Seeding (HLSS) that allows to improve longitudinal coherence and spectral power of a Self-Amplified Spontaneous Emission (SASE) FEL. This concept was successfully tested at FLASH2 in the range of 4.5 - 15 nm and at PAL XFEL at 1 nm. In this contribution we present recent results from the European XFEL where we successfully demonstrated operation of HLSS FEL at 5.9 A, thus pushing harmonic lasing for the first time into the Angstrom regime.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB025

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paper received ※ 09 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB031

FERMI Configuration for the Echo Enabled Harmonic Generation Experiment

laser, FEL, electron, experiment

1752

E. Allaria, D. Castronovo, M. Cautero, I. Cudin, M.B. Danailov, B. Diviacco, L. Giannessi, M. Veronese, M. Zangrando
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy

The FERMI FEL-2 undulator line, normally operated in the double stage high gain harmonic generation with the fresh bunch (HGHG-FB) has been temporary modified to allow operating the FEL in the Echo Enabled Harmonic Generation (EEHG) scheme. An increase of the dispersion in the delay-line was required together with a replacement of the second stage modulator allowing the electron beam to resonantly interact with a second seed laser. Another critical component of the EEHG setup is a new manipulator installed in the delay-line chicane and hosting additional diagnostic components. In this work we describe in some detail these new components that allowed a successful demonstration of the EEHG at harmonics as high as 101.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB031

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paper received ※ 17 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB047

Proposal of the Reflection Hard X-Ray Self-Seeding at the SHINE Project

FEL, undulator, polarization, lattice

1792

T. Liu, C. Feng
SARI-CAS, Pudong, Shanghai, People’s Republic of China

FEL self-seeding has been demonstrated a great advantage for the generation of a fully coherent and high brightness X-ray pulse experimentally. Generally, transmission monochromators with single crystal are adopted worldwide, such as LCLS, PAL-XFEL and European-XFEL. Recently, the self-seeding scheme based on a reflection monochromator with a double-crystal is proposed and demonstrated at SACLA successfully. In view of several potential advantages of the reflection type, here we give the proposal of the reflection monochromator based self-seeding and enable the application on the SHINE project. This manuscript is mainly focus on monochromator schemes at SHINE, instead of FEL simulations. We will present considerable schemes based on the specific undulator line.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB047

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB072

Compact APPLE X for Future SXL FEL and 3 GeV Ring at MAX IV Laboratory

undulator, polarization, vacuum, FEL

1833

H. Tarawneh, P. N’gotta, L.K. Roslund, A. Thiel, K. Åhnberg
MAX IV Laboratory, Lund University, Lund, Sweden

An overview of the design of compact elliptically polarizing undulator with small round magnetic gap to provide full polarization control of synchrotron radiation in a more cost effective manner and consuming less built in space than the state of the art devices. This type of undulator is meant as source for the potential future Soft X-ray (SXL) FEL beamline using the linear accelerator at MAX IV. In addition, it offers new capabilities for future beamlines at the 3 GeV ring to use full polarization control to photon energies using the fundamental harmonic which are not attainable with today’s technology of the out-of-vacuum insertion devices at 3 GeV beam energy.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB072

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paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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TUPRB081

Beam Motion and Photon Flux Dips during Injection at the Taiwan Photon Source

injection, kicker, betatron, vacuum

1848

C.H. Huang, H.-P. Chang, C.H. Chen, Y.-S. Cheng, P.C. Chiu, C.-S. Fann, K.T. Hsu, K.H. Hu, C.Y. Liao, Y.-C. Liu, C.Y. Wu
NSRRC, Hsinchu, Taiwan

The Taiwan photon source (TPS) is a 3 GeV synchrotron light source now in routine operation at the NSRRC. At the beginning of beam commissioning, significant photon flux dips could be observed at injection due to a blow-up of the beam size. To eliminate this transient effect, all four kickers were rematched. The leakage field was shielded and the induced current loops at vacuum chambers in the injection area were also eliminated. These efforts reduced the horizontal betatron oscillations and orbit distortions to around one-tenth. In order to decrease the recovery time of photon dips during injection, the operational chromaticity was reduced to improve incoherent effects. After all those improvements, the photon flux dips during injection dropped to 30 % and the recovery time to less than 1 msec.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB081

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paper received ※ 17 April 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB088

Generation of High Peak Power Hard X-Rays at LCLS-II with Double Bunch Self-seeding

FEL, electron, laser, undulator

1863

A. Halavanau, F.-J. Decker, Y. Ding, C. Emma, Z. Huang, J. Krzywiński, A.A. Lutman, G. Marcus, C. Pellegrini, D. Zhu
SLAC, Menlo Park, California, USA

Funding: This work was supported by the U.S. Department of Energy Contract No. DE-AC02-76SF00515.
We propose to use existing LCLS copper S-band linac double bunch infrastructure to significantly improve LCLS-II hard X-ray performance. In our setup, we use the first bunch to generate a strong seeding X-ray signal, and the second bunch, initially traveling off-axis, to interact with the seed in the amplifier undulator and generate a near TW, 15 fs duration X-ray pulse in the 4 to 8 keV photon energy range. We investigate, via numerical simulations, the required transverse beam dynamics and the four crystals X-ray monochromator to be added to the existing LCLS-II beamline and discuss the final properties of the hard X-ray pulses and their potential application in high intensity, high-field physics experiments, including QED above the Schwinger critical field.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB088

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paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB089

Undulator Radiation Generated by a Single Electron

electron, undulator, experiment, radiation

1867

A. Halavanau, Z. Huang, C. Pellegrini, T.O. Raubenheimer
SLAC, Menlo Park, California, USA
I. Lobach
University of Chicago, Chicago, Illinois, USA
S. Nagaitsev
Fermilab, Batavia, Illinois, USA
D. Seipt
HZDR, Dresden, Germany

Funding: This work was supported by the U.S. Department of Energy Contract No. DE-AC02-76SF00515.
The facilities providing single electron beams are currently being commissioned at Fermilab and will be at SLAC. Recently, Fermilab’s IOTA ring routinely demonstrated circulation of a single electron at 100 MeV beam energy. Alternatively, SLAC is working on constructing LCLS-II an X-ray FEL driven by a 4 GeV SRF linac. A parasitic beamline, S30XL, is planned that will extract 4 GeV dark current from between the primary LCLS-II electron bunches. The dark current will be delivered to End Station A and can work independently of LCLS-II experiments. The dark current will be bunched at a frequency of 46 MHz while extracted current varied from single electrons to 10’s of nA. In the present paper, we estimate the feasibility of propagating single electron beams through a conventional undulator, placed in the IOTA and S30XL beamlines. We explore the possible observable effects and experimental parameters range. In addition, we focus on potential applications of such beams in systems for high fidelity quantum measurements.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB089

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paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB090

Preliminary Considerations of Atomic Inner-Shell X-Ray Laser for Self-Seeding at LCLS-II

FEL, simulation, radiation, experiment

1871

A. Halavanau, C. Pellegrini, J. Wu
SLAC, Menlo Park, California, USA
A.I. Benediktovitch
EuXFEL, Hamburg, Germany
N. Rohringer
Max Planck Institute for the Physics of Complex Systems, Dresden, Germany

Funding: This work was supported by the U.S. Department of Energy Contract No. DE-AC02-76SF00515.
The atomic inner-shell X-ray lasing, induced by the irradiation of focused XFEL SASE pulses, was demonstrated in gases, liquid jets and solids. In this proceeding, we discuss the possible use of this concept in self-seeding scheme at LCLS-II. We provide a preliminary study of different lasing media and corresponding SASE XFEL parameters. For the case of noble gas inner-shell X-ray laser, we study the requirements for gas pressure and XFEL pulse focusing. Finally, we discuss possible designs of this system and its advantages in LCLS-II operations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB090

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paper received ※ 13 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB094

New Superconducting Undulator Magnetic Measurement System for the Advanced Photon Source Upgrade

GUI, undulator, vacuum, storage-ring

1881

M. Kasa, E.R. Anliker, Y. Ivanyushenkov, Y. Shiroyanagi
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
Magnetic measurements of existing superconducting undulators (SCUs) are performed under normal operating conditions after final assembly into the cryostat and before installation on the Advanced Photon Source (APS) storage ring. The SCU cryostat for the APS upgrade has been scaled in length from the current cryostat and will contain two SCUs. While some aspects of the current measurement system are desirable to retain, such as a room temperature measurement bore, scaling the current measurement techniques to the length required for the APS upgrade cryostat is not feasible. To address these challenges a unique system has been developed at the APS to allow measurements of the two SCU magnets in the long cryostat. The measurement system developed allows the magnets to be operated under normal operating conditions while maintaining the measurement equipment at room temperature and atmospheric pressure.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB094

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPRB095

Superconducting Undulators for the Advanced Photon Source Upgrade

undulator, vacuum, electron, operation

1884

M. Kasa, E.R. Anliker, J.D. Fuerst, Q.B. Hasse, Y. Ivanyushenkov, I. Kesgin, Y. Shiroyanagi, E. Trakhtenberg
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
The magnetic devices group at the Advanced Photon Source (APS) is in the process of designing and developing superconducting undulators (SCUs) for the APS upgrade. While similar in some aspects to previous SCU systems currently in operation at the existing APS, the new SCU systems will include two undulators installed in one cryostat which occupies an entire straight section of the storage ring. Straight sections containing planar undulators will either be configured as ’in-line’, where the two undulators behave as one source, or canted, where the two undulators are operated independently. Also under development is a superconducting arbitrary polarizing emitter (SCAPE) which can produce planar, elliptical, and helical undulator fields.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPRB095

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paper received ※ 14 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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TUPTS026

Negative Electron Affinity GaAs Cathode Activation With CsKTe Thin Film

cathode, electron, vacuum, gun

1986

M. Kuriki
KEK, Ibaraki, Japan
K. Masaki
HU/AdSM, Higashi-Hiroshima, Japan

Funding: This work is partly supported by Japan-US Cooperative grant for scientific studies, Grant aid for scientific study by MEXT Japan (KAKENHI).
Negative Electron Affinity (NEA) GaAs cathode is an unique device which can generate a highly polarized electron beam with circularly polarized light. The NEA surface is conventionally made by Cs and \rm O/NF₃ adsorption on the cleaned p-doped GaAs crystal, but the robustness of the cathode is very limited, so that the electron emission is easily lost by residual gas adsorption, ion back-bombardment, etc. To improve the cathode robustness, NEA activation with a stable thin-film on GaAs surface according to Hetero junction hypothesis has been proposed by the author. An experiment of the NEA activation with CsKTe thin film was carried out at Hiroshima University and a significant electron emission with 1.43 eV photon was observed which strongly suggested NEA activation. The cathode showed 16 to 20 times improvement of lifetime comparing to GaAs activated with Cs and O.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS026

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paper received ※ 26 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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TUPTS069

A Plasmonic Niobium Photocathode for SRF Gun Applications

cathode, gun, laser, cavity

2079

F.E. Hannon
JLab, Newport News, Virginia, USA
G. Andonian, L.H. Harris
RadiaBeam, Marina del Rey, California, USA

The typical quantum efficiency of niobium is of the order 10^-4, whilst also requiring UV lasers for emission. This paper presents the results of a plasmonic niobium surface that operates with IR laser via multiphoton emission.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS069

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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TUPTS089

Observations of the Femtosecond Laser-Induced Emission From the Diamond Field Emitter Tips

laser, electron, cathode, experiment

2130

E.I. Simakov, H.L. Andrews, R.L. Fleming, D. Kim, V.N. Pavlenko
LANL, Los Alamos, New Mexico, USA
D.S. Black, K.J. Leedle
Stanford University, Stanford, California, USA

Funding: Los Alamos National Laboratory LDRD Program
We present the results of experimental observation of emission from single diamond field emitter tips when triggered by an ultra-short laser pulse. Diamond field emitter array (DFEA) cathodes were originally proposed for applications that require large current densities. DFEAs represent periodic arrays of diamond pyramids with micron-size dimensions and tips with diameters of the order of tens of nanometers. DFEAs are known to produce significant currents in field emission regime under direct current (DC) fields and in radio-frequency (RF) guns. It has been proposed that single diamond tip emitters can be employed for production of small tightly focused electron beams for dielectric laser accelerators (DLAs) that accelerate particles using the energy of light produced by infrared lasers. To generate short electron bunches required by DLAs diamond pyramids may be triggered with a laser. We have recently observed emission produced by a single diamond pyramid when triggered by a laser at different wavelengths from 256 nm to 2020 nm. We have conducted studies with the goal to understand mechanism of the emission. We clearly observed the change in emission mechanism when the wavelength changed from 256 nm to 512 nm. We believe that while the emission at 256 nm is a clear photoemission, the emission at longer wavelengths is likely the field emission caused by intense electric fields of the laser.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-TUPTS089

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paper received ※ 14 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPMP009

Renovation of Off-Axis Beam Injection Scheme for Next-Generation Photon Sources

septum, injection, vacuum, kicker

2318

S. Takano, K. Fukami, C. Kondo, M. Masaki, M. Oishi, M. Shoji, K. Tamura, T. Taniuchi, T. Watanabe, K. Yanagida
JASRI, Hyogo, Japan
H. Akikawa, K. Sato
Nihon Koshuha Co. Ltd, Yokohama, Japan
K. Fukami, T. Hara, T. Inagaki, C. Kondo, M. Oishi, S. Takano, H. Tanaka, T. Watanabe
RIKEN SPring-8 Center, Hyogo, Japan
K. Hamato, J. Kataoka, K. Kusano, K. Ogata, Y. Saito
TOKIN, Sendai, Miyagi, Japan

Funding: Work supported by Ministry of education, culture, sports, science and technology JAPAN (MEXT).
Photon sources are looking for performance upgrades by pursuing higher photon brilliance and coherence these years. The trend is pushing the lattice design to lower the beam emittance, which naturally results in the narrower dynamic aperture. One bottleneck in the upgrades is a beam injection system capable of accumulating required beam intensity and keeping top-up operations with such narrow apertures. Beam injection with a nonlinear kicker and transverse/longitudinal on-axis injections are now in the limelight. However, these techniques still need time to be put into practical use. We take an alternative approach for the SPring-8 upgrade, SPring-8-II, renovating the off-axis beam injection scheme to address the following requirements for the coming diffraction-limited storage rings (DLSRs): minimizing of both injection beam amplitude and perturbation to stored beam, and topping-up functionality. This presentation will overview the renewed off-axis beam injection scheme and report the development status of the following three key components: 1) permanent magnet based DC septum magnet, 2) in-vacuum pulse septum magnet, and 3) twin kickers driven by a single solid state pulser.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPMP009

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paper received ※ 10 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPGW031

Measurement of Cherenkov Diffraction Radiation from a Short Electron Bunches at t-ACTS

electron, radiation, experiment, detector

2536

S. Ninomiya, H. Hama, F. Hinode, K. Kanomata, S. Kashiwagi, S. Miura, N.M. Morita, T. Muto, I. Nagasawa, K. Nanbu, H. Saito, K. Takahashi, H. Yamada
Tohoku University, Research Center for Electron Photon Science, Sendai, Japan

Cherenkov Diffraction Radiation (ChDR) can be considered as a tool of non-destructive beam diagnostics. It also has the feature that the photon flux of ChDR is proportional to the thickness of the dielectric used as the radiator and can be much larger than ordinary diffraction radiation. An experimental set-up for the measurement of coherent ChDR from short electron bunches of about 100 fs is being prepared at t-ACTS, Tohoku University. Results of a basic experimental study about coherent ChDR will be presented.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW031

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paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPGW062

Synchrotron Light Diagnostic Beamline Design for HEPS Storage Ring

emittance, diagnostics, storage-ring, lattice

2619

D.C. Zhu, J.S. Cao, Y.F. Sui, J.H. Yue
IHEP, Beijing, People’s Republic of China

Funding: National Nature Science Foundation of China(11605213)
High Energy Photon Source (HEPS) is a 6 GeV ul-tralow-emittance storage ring light source to be built in Beijing, China. With a multiple-bend achromat lattice design, the storage ring is expected to achieve an ul-tralow emittance of 34 pm.rad. The horizontal and verti-cal beam sizes will be in the sub-10 μm level. Beam emit-tance will be measured with x-ray diagnostic beamline at a low dispersion bending magnet source point. A visible light beamline will be designed to measure the bunch length and purity. In this paper, we will introduce the x-ray beamline, which combine with different techniques to resolve beam sizes and emittance.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW062

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPGW077

Recent Results using Incoherent Cherenkov Diffraction Radiation for Non-Invasive Beam Diagnostics

radiation, experiment, diagnostics, beam-diagnostic

2654

M. Bergamaschi, R. Kieffer, T. Lefèvre, S. Mazzoni
CERN, Geneva, Switzerland
A. Aryshev
KEK, Ibaraki, Japan
P. Karataev
Royal Holloway, University of London, Surrey, United Kingdom
P. Karataev, K. Lekomtsev
JAI, Egham, Surrey, United Kingdom
A. Potylitsyn
TPU, Tomsk, Russia
A. Schloegelhofer
TU Vienna, Wien, Austria

When a relativistic charged particle travels at a short distance from the surface of dielectric material Cherenkov Diffraction Radiation (ChDR) is produced inside the dielectric. Recent observation of incoherent ChDR in the visible spectrum has opened the possibility of using this radiation for non-invasive beam size and position measurements. An experimental test to study this technique for highly directional beam position measurement has been initiated on the CLEAR facility at CERN, whilst another experimental investigation is underway at the Accelerator Test Facility 2 (ATF2) at KEK, Japan, to measure the resolution limit of ChDR for beam imaging diagnostics. This contribution presents the latest experimental results from both of these test facilities.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW077

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paper received ※ 01 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPGW087

Control System Studio to Monitor Front End and Beamlines Status as well as Light Source Stability

electron, status, operation, controls

2687

W.Y. Lin, B.Y. Chen, C.S. Huang, C.H. Kuo, T.Y. Lee
NSRRC, Hsinchu, Taiwan

The primary task during a shift change at the Taiwan Photon Source Accelerator Operations team is to know the exact status of the machine, so that problems can be discovered immediately and solved when the machine behaves abnormal. To provide a stable beam during top-up operation, it is necessary to monitor closely the stability of the light source, of front end areas and beamlines. Should any abnormality occur, the operator would initiate initial troubleshooting and adjustments, inform users and sub-system staff members and perform subsequent first anal-yses and system optimizations. In this article, we describe how to sort through the nec-essary information with the Control System Studio (CSS) design page. There are currently seven beamlines in operation at the Taiwan Photon Source (05, 09, 21, 23, 25, 41, 45) and more new beamlines will be added in the future. Com-pared with other tools, CSS is intuitive and easy to revise. No matter weather adding new parameters or changing settings, the operation team can quickly get familiar with the machine status and perform an interface upgrade.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW087

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paper received ※ 27 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW093

Commissioning of the Prototype for a New Gas Curtain Beam Profile Monitor Using Beam Induced Fluorescence for HL-LHC

electron, gun, background, experiment

2709

A. Salehilashkajani, C.P. Welsch, H.D. Zhang
The University of Liverpool, Liverpool, United Kingdom
M. Ady, N. Chritin, J. Glutting, O.R. Jones, R. Kersevan, T. Marriott-Dodington, S. Mazzoni, A. Rossi, G. Schneider, R. Veness
CERN, Geneva, Switzerland
P. Forck, S. Udrea
GSI, Darmstadt, Germany
C.P. Welsch, H.D. Zhang
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: This work is supported by the HLLHCUK project and the STFC Cockcroft Institute core grant No. ST/G008248/1.
A new supersonic gas-jet curtain based beam profile monitor is under development for minimally invasive simultaneous transverse profile diagnostics of proton and electron beams, at pressures compatible with LHC. The monitor makes use of a thin gas-jet curtain angled at 45 degrees with respect to the charged particle beams. The fluorescence caused by the interaction between the curtain and the beam can then be detected using a dedicated imaging system to determine its transverse profile. This contribution details design features of the monitor, discusses the gas-jet curtain formation and presents various experimental tests, including profile measurements of an electron beam using nitrogen and neon curtains. The gas-jet density was estimated by correlating it with the number of photons detected by the camera. These measurements are then compared with results obtained using a movable pressure gauge. This monitor has been commissioned in collaboration with CERN, GSI and the University of Liverpool. It serves as a first prototype of a final design that will be placed in the LHC beam line to measure the profile of the proton beam.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW093

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paper received ※ 14 May 2019 paper accepted ※ 20 May 2019 issue date ※ 21 June 2019

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WEPGW096

Development of Supersonic Gas-Sheet-Based Beam Profile Monitors

electron, background, radiation, monitoring

2717

H.D. Zhang, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
M. Ady, J. Glutting, O.R. Jones, T. Marriott-Dodington, S. Mazzoni, A. Rossi, G. Schneider, R. Veness
CERN, Geneva, Switzerland
P. Forck, S. Udrea
GSI, Darmstadt, Germany
A. Salehilashkajani, C.P. Welsch, H.D. Zhang
The University of Liverpool, Liverpool, United Kingdom

Funding: HL-LHC project funded by STFC and CERN, and the STFC Cockcroft core grant No. ST/G008248/1.
Non-destructive beam profile monitoring is very desirable, essentially for any particle accelerator but particularly for high-energy and high-intensity machines. Supersonic gas jet-based monitors, detecting either the ionization or fluorescence of a gas sheet interacting with the primary beam to be characterized, allow for minimally invasive measurements. They can also be used over a wide energy range, from keV to TeV beams. This contribution gives an overview of the jet-based ionization and fluorescence beam profile monitors which have been developed, built and tested at the Cockcroft Institute. It discusses gas sheet generation, vacuum considerations, choice of gas species and detection methods.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW096

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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WEPGW120

Fluorescence-Based Imaging Diagnostic for High Average Power Deuteron Beam

neutron, diagnostics, quadrupole, target

2777

R.A. Marsh, S.G. Anderson, D.J. Gibson, J. Hall, B. Rusnak
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.
Lawrence Livermore National Laboratory is developing an intense, high-brightness fast neutron source to create sub-millimeter-scale resolution neutron radiographs and imag-es. An intense source (10¹¹ n/s/sr at 0 degrees) of fast neutrons (10 MeV) will be produced using a pulsed 7 MeV, 300μAmp average-current commercial deuteron accelerator producing a small (1.5 mm diameter) beam spot size to achieve high resolution. The high average power beam is a challenge for diagnostics, and a precise full power emittance measurement is critical to benchmark the system performance. A fluorescence-based beam profiling diagnostic has been selected, and this paper presents the design for the system including chamber layout, light yield calculations, and imaging system details.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPGW120

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paper received ※ 15 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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WEPRB116

X-ray Pinhole Camera for Emittance Measurements in Solaris Storage Ring

emittance, storage-ring, radiation, diagnostics

3084

A. Kisiel, A.M. Marendziak, M. Ptaszkiewicz, A.I. Wawrzyniak
Solaris National Synchrotron Radiation Centre, Jagiellonian University, Kraków, Poland

X-ray pinhole camera is widely used system for the transverse beam profile measurement and emittance feedback. However this method is predominantly applied to the middle and high energy storage rings. At Solaris storage ring with the nominal energy of 1.5 GeV, the design of the beamline was modified to provide sufficient X-ray photon flux for proper imaging. The successful installation and commissioning of the X-ray pinhole beamline allows now to measure the emittance and helps in proper 3rd harmonic cavities tuning against the coupled bunch mode instabilities. The paper describes the design details, simulations and measurement results obtained during the beamline operation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPRB116

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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WEPTS104

Synchrotron Radiation Reflections in the CLIC Beam Delivery System

detector, collider, synchrotron, radiation

3363

D. Arominski, A. Latina, A. Sailer, D. Schulte
CERN, Meyrin, Switzerland

Synchrotron radiation (SR) reflection is an important issue for future linear colliders. High fluxes of the SR might impact the performance of the detector, through irradiation of the forward luminosity and beam quality calorimeters or of the innermost layers of the vertex detector. The photon reflections depend on the beam pipe apertures’ size, their shape, and materials used with various surface roughness. In this work, we present a study of SR including reflection for the 380 GeV and 3 TeV beam parameters and optics of the Compact Linear Collider’s Final Focus System. The simulations of the SR reflections using the Synrad+ software are presented and the impact on the detector is discussed.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-WEPTS104

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paper received ※ 29 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THYPLM1

Development of the Vertically Polarizing Hard X-Ray Undulator Segments for the Linear Coherent Light Source Upgrade (LCLS-II) Project

undulator, operation, free-electron-laser, electron

3408

M. Leitner, D. Arbelaez, J.N. Corlett, A.J. DeMello, L. Garcia Fajardo, D. Leitner, S. Marks, K.A. McCombs, T. Miller, D.V. Munson, J. Niu, K.L. Ray, D.A. Sadlier, D. Schlueter, E.J. Wallén
LBNL, Berkeley, California, USA
H. Bassan, D.E. Bruch, D.S. Martinez-Galarce, H.-D. Nuhn, M. Rowen, Z.R. Wolf
SLAC, Menlo Park, California, USA
C.W. Chen
NSRRC, Hsinchu, Taiwan

Funding: Work supported by the Director, Oﬃce of Science, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The Linear Coherent Light Source II (LCLS-II) is a free electron laser facility currently in its final construction stage at Stanford Linear Accelerator Center. The project includes two variable-gap, hybrid-permanent-magnet undulator lines: A soft x-ray undulator line with 21 undulator segments optimized for a photon energy range from 0.2 keV to 1.3 keV and a hard x-ray undulator line with 32 undulator segments designed for a photon energy range from 1.0 keV to 25.0 keV. This paper focuses on the design, development, and performance of the hard x-ray undulator line which utilizes uniquely-developed, vertically-polarizing undulators. To fully compensate the magnetic force throughout the entire gap range these devices incorporate non-linear spring systems which permit the construction of relatively compact undulators. However, significant magnetic field repeatability challenges have been encountered during prototyping of this novel design. The paper describes the innovative design improvements that were implemented which lead to reaching the LCLS-II required performance. These final design solutions can also be advantageous improving the operation of any future undulator design.

Slides THYPLM1 [28.498 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THYPLM1

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THYYPLS3

A Remote-Controlled Robot-Car in the TPS Tunnel

controls, radiation, operation, laser

3435

T.Y. Lee, B.Y. Chen, T.W. Hsu, B.Y. Huang, C.H. Kuo, W.Y. Lin
NSRRC, Hsinchu, Taiwan

A remote-controlled robot-car named ’PhotonBot’ was put into the TPS accelerator tunnel and is equipped with a 360 degrees LiDAR for SLAM and navigation, two cameras for perception and first-person view, and a thermal imaging system. The robot can be remotely controlled and can send data to a remote PC through Wi-Fi. With SLAM, it can go more freely without being restricted to a designated path. In order to ensure it can work continuously, there is a wireless charging station in case of a low battery.

Slides THYYPLS3 [18.013 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THYYPLS3

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paper received ※ 09 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPMP008

Feasibility Study on Mo-99 Production Using Hybrid Method Based on High Power Electron Accelerator

target, neutron, radiation, electron

3462

A. Taghibi Khotbeh-Sara, F. Rahmani
KNTU, Tehran, Iran
F. Ghasemi
NSTRI, Tehran, Iran
H. Khalafi
AEOI, Tehran, Iran
M. Mohseni Kejani
Shahid Beheshti University, Tehran, Iran

In this study, the idea 99Mo production using hybrid method based on electron accelerator has been pre-sented. Two different main production channels of 100Mo(γ,n)99Mo and 98Mo(n,γ)99Mo can be used for 99Mo production in this system. By considering high power Linac (30 MeV, 1 mA in average beam current) and one-stage approach, the calculation of 100Mo(γ,n)99Mo reactions in the optimized 100Mo target in two different designs (strip and disc) has been simu-lated. It is predicted that about 61 and 53 Ci of 99Mo activity per 24-hour irradiation on the strip target and the disc plates can be achieved, respectively. The threshold energy of photoneutron at 100Mo is about 9 MeV, so a large part of bremsstrahlung photons cannot participate in photoneutron reaction. For feasibility study, new hybrid approach has been tested by 10 MeV Rhodotron. Due to the low threshold of photo-neutron in deuteron (about 2.2 MeV) and significant low energy photons in 100Mo, photoneutron flux is available. So, Molybdenum target in heavy water Tank increases the production yield of 99Mo using neutron absorption reaction in 98Mo. The total activity of 99Mo has been predicted about 0.23 Ci per 24 hours e-beam irradiation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP008

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPMP049

Sequential Excitation Scheme for Laser Stripping of Hydrogen Ion Beams

laser, electron, cavity, proton

3558

Y. Liu, A.V. Aleksandrov, S.M. Cousineau, T.V. Gorlov, A. Rakhman
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
Resonant laser excitation of the electron in a hydrogen atom is essential to achieve high-efficiency laser stripping of hydrogen ion (H⁻) beam. In the laser stripping experiments recently carried out at SNS, an ultra-violet (UV) laser was used to excite the electrons in 1-GeV hydrogen atoms from the n=1 state to the n=3 state. In this talk, we propose a sequential resonant excitation scheme by using two laser beams to excite electrons in a sequence of two steps: from the n=1 state to the n=2 state and from the n=2 state to any higher state. The advantages of the sequential resonant excitation scheme include (1) lower laser power requirement due to higher transition probability in the first excitation step and (2) possibility of shifting the stripping laser wavelength from UV regime to longer wavelengths. An application of the sequential resonant excitation scheme in combination with the double-resonance optical cavity technology to the laser stripping of 1.3-GeV H⁻ beam (envisioned in the SNS proton power upgrade project) will be described.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPMP049

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paper received ※ 14 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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THPGW014

Tolerance Studies and Limitations for Photonic Bandgap Fiber Accelerators

laser, acceleration, simulation, electron

3605

L. Genovese, R.W. Aßmann, U. Dorda, M. Kellermeier, W. Kuropka, F. Lemery, F. Mayet
DESY, Hamburg, Germany
W. Kuropka, F. Mayet
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Laser-driven hollow core photonic bandgap (PBG) fibers were proposed by Lin in 2001 as high-gradient accelerators. The central defect in the transversely periodic lattice supports an accelerating mode for synchronous acceleration in the ultra-relativistic regime. The optical frequencies in such dielectric laser accelerators motivate a sensitivity and tolerance study to overcome manufacturing imperfections. Finally we discuss the propagation characteristics of Lin-fibers and find that small-bandwidth (~ns) pulses would be needed for efficient acceleration over longer distances.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW014

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paper received ※ 16 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPGW033

Numerical Study of Photonic-Crystal-Based Dielectric Accelerators

GUI, acceleration, electron, impedance

3653

G. Torrisi, L. Celona, S. Gammino, D. Mascali, G. Sorbello
INFN/LNS, Catania, Italy
C. De Angelis, A. Locatelli
University of Brescia, Brescia, Italy
G.S. Mauro
INFN/LNL, Legnaro (PD), Italy
G. Sorbello
University of Catania, Catania, Italy

All-dielectric electromagnetic band gap (EBG) waveguides structures promise significant improvement of accelerating gradient of laser-driven acceleration with the potential to miniaturize the accelerator itself. In this work we study photonic crystal structures designed for acceleration of relativistic electrons. We explore the performance of the all-dielectric EBG accelerating waveguide structures thanks to full wave electromagnetic simulations of couplers and accelerating waveguides. The characteristic interaction impedance, accelerating gradient and all the key parameters that are typically used to characterize linear accelerators are evaluated and used to compare the properties of the accelerating mode field distribution in different geometries.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW033

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paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPGW051

MCP Based Detectors of European XFEL

FEL, detector, radiation, electron

3703

E. Syresin, O.I. Brovko, A.Yu. Grebentsov
JINR, Dubna, Moscow Region, Russia
W. Freund, J. Grünert
EuXFEL, Schenefeld, Germany
M.V. Yurkov
DESY, Hamburg, Germany

Radiation detectors based on microchannel plates (MCP) are used for measurements of the SASE process of the European XFEL. Detectors operate in a wide dynamic range from the level of spontaneous emission to the saturation level (between a few nJ and 25 mJ) and in a wide wavelength range from 0.05 nm to 0.4 nm for SASE1 and SASE2 and from 0.4 nm to 4.43 nm for SASE3. Photon pulse energies are measured by the MCPs with an anode and by a photodiode. The MCP imager measures the photon beam image with a phosphor screen. Three MCP detectors are installed, one behind each SASE undulator (SASE1, SASE2, and SASE3). Calibration and first experiments with the MCP detectors are under discussion.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW051

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paper received ※ 29 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPGW061

The K12 Beamline for the KLEVER Experiment

target, detector, experiment, background

3726

M.W.U. Van Dijk, D. Banerjee, J. Bernhard, M. Brugger, N. Charitonidis, N. Doble, L. Gatignon, A. Gerbershagen, E. Montbarbon, B. Rae, M.S. Rosenthal, B. Veit
CERN, Geneva, Switzerland
G. D’Alessandro
JAI, Egham, Surrey, United Kingdom
M. Moulson
INFN/LNF, Frascati, Italy

The KLEVER experiment is proposed to run in the CERN ECN3 underground cavern from 2026 onward. The goal of the experiment is to measure BR(KL -> pi0 nu nu), which could yield information about potential new physics, by itself and in combination with the measurement of BR(K+ -> pi+ nu nu) of NA62. A full description will be given of the considerations in designing the new K12 beamline for KLEVER, as obtained from a purpose made simulation with FLUKA. The high intensities required by KLEVER, 2·10¹³ protons on target every 16.8s, with 5·10¹⁹ protons accumulated over 5~years, place stringent demands on adequate muon sweeping to minimize backgrounds in the detector. The target and primary dump need to be able to survive these demanding conditions, while respecting strict radiation protection criteria. A series of design choices will be shown to lead to a neutral beamline sufficiently capable of suppressing relevant backgrounds, such as photons generated by pi0 decays in the target, and Lambda -> npi0 decays, which mimic the signal decay.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW061

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paper received ※ 30 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPGW071

Genetic Optimisation of Beamline Design for DIAMOND

synchrotron, framework, radiation, experiment

3753

F. Bakkali Taheri, M. Apollonio, R. Bartolini, B. Singh
DLS, Oxfordshire, United Kingdom
R. Bartolini, J. Li
JAI, Oxford, United Kingdom
R. Bartolini
Oxford University, Physics Department, Oxford, Oxon, United Kingdom

The problem of optimisation of beamline structures is studied, from the point of view of multi-objective genetic algorithms. While this approach has been successfully used in the exploration of potential particle accelerator lattices, it has never been applied to beamline design. In this paper, the Non-Dominated Sorting Genetic Algorithm II (NGSA II) is used to optimize a structure where photons are assumed to propagate through the optical elements according to the wavefront model as implemented in SRW. It is shown that appropriate objective functions can help to set up an interesting set of parameters, with competitive computational resources compared to the traditional approach. Examples illustrating this optimization method are shown in the context of DIAMOND.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPGW071

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paper received ※ 13 May 2019 paper accepted ※ 18 May 2019 issue date ※ 21 June 2019

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THPRB033

Development Status of RF Reference Phase Stabilization System for SuperKEKB Injector LINAC

linac, controls, feedback, distributed

3879

N. Liu, B. Du
Sokendai - Hayama, Hayama, Japan
D.A. Arakawa, H. Katagiri, T. Kobayashi, T. Matsumoto, S. Michizono, T. Miura, F. Qiu, Y. Yano
KEK, Ibaraki, Japan
T. Matsumoto, T. Miura, F. Qiu
Sokendai, Ibaraki, Japan

SuperKEKB injector linear accelerator (LINAC) has 600 m beam lines which consist of 8 sectors. The 2856 MHz RF reference signals are distributed to each sector with long phase stabilized optical fiber (PSOF). The RF reference phase stability requirement is estimated to be 0.2°(RMS) corresponding to 200 fs. The prototype of RF reference phase stabilization system with single mode optical circulator was implemented and demonstrated in the laboratory. The returned phase drift is compensated by a piezo-driven fiber stretcher. The transmitted phase through 120 m PSOF is stabilized to 41 fs (pk-pk), which fulfilled the requirement. This paper introduces the RF reference phase stabilization system and reports the preliminary feedback result.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB033

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB062

New Orbit Correction Method Based on SVDC Algorithm for Ring Based Light Sources

feedback, lattice, controls, simulation

3943

X.Y. Huang, J.S. Cao, Y.Y. Du, Y.H. Lu, H.Z. Ma, Y.F. Ma, Y.F. Sui, S.J. Wei, Y. Wei, Q. Ye, X.E. Zhang, D.C. Zhu
IHEP, Beijing, People’s Republic of China

Funding: Union Foundation of excellent post-doctoral of China
Orbit feedback system is essential for realizing the exceeding beam stability in modern ring based light sources. Most advanced light sources adopt the global correction scheme by using singular value decomposition (SVD) algorithm. In this paper, a new SVD with constraints method (SVDC) is proposed to correct the global and local orbit simultaneously. Numerical simulations are presented with the case of High Energy Light Source (HEPS) by comparing classic algorithms. The results show that SVDC is very effective for orbit correction and very easy to implement.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB062

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paper received ※ 09 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB090

Laboratory Exhaust Gas Treatment Systems at TPS

controls, synchrotron, status, experiment

4029

J.-C. Chang, W.S. Chan, Z.-D. Tsai
NSRRC, Hsinchu, Taiwan

There are three main laboratory exhaust gas treatment systems equipped at Taiwan Photon Source (TPS): acid/alkaline system for corrosive acids and alkalis, volatile solvents, and other hazardous chemicals; organic system for biological experiments; and general system for other gas. Gas is collected in hoods installed near the sources of contamination in laboratories. The contamination then is transported through duct to the gas treatment equipment installed outside of the TPS experimental hall.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB090

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paper received ※ 06 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPRB091

APPLICATION PROGRAMS FOR TPS BEAM TRIP ANALYSIS

power-supply, kicker, electron, operation

4032

B.Y. Chen, T.W. Hsu, B.Y. Huang, C.S. Huang, C.H. Kuo, T.Y. Lee, W.Y. Lin
NSRRC, Hsinchu, Taiwan

For the Taiwan Photon Source (TPS), the orbit inter-lock system is one of the most important machine pro-tection systems. It is the fastest and the most preferred system to detect abnormalities to prevent possible dam-ages caused by magnet power supply failures or subsys-tems failures. In order to monitor electron orbit changes during a beam trip, we developed the ’orbit monitoring and recording tool’, the ’TBT BPM analysis tool’ and the ’magnet power supply recording and analysis tool’ to assist us in the failure analysis as will be discussed in this paper.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB091

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB095

A Simulation Framework for Photon-Particle Interactions for Laserwires and Further Applications

laser, electron, scattering, simulation

4045

S.E. Alden, S.M. Gibson, L.J. Nevay
JAI, Egham, Surrey, United Kingdom

A model has been developed for simulating photon-particle interactions with Beam Delivery Simulation (BDSIM). BDSIM is a high energy physics program that utilises the Geant4, CLHEP, and ROOT libraries to seamlessly track particles through an accelerator. The photon-particle interactions introduce the capability for modelling a range of applications in accelerator physics. One such application is a laserwire which is a minimally invasive diagnostic technique to measure beam profiles and emittance. In this paper we describe the recent implementation of inverse Compton scattering and electron stripping of Hydrogen ions. This is demonstrated on an example beamline.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB095

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paper received ※ 15 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB102

Monte Carlo Optimization of Fast Beam Loss Monitors for LCLS-II

detector, target, electron, simulation

4066

M. Santana-Leitner, C.I. Clarke, A.S. Fisher, A.M. Harris, C. Hast, T.T. Liang
SLAC, Menlo Park, California, USA
E. Griesmayer
CIVIDEC Instrumentation, Wien, Austria

Funding: Work supported by U.S. Department of Energy contract DE-AC02-76SF00515
Commissioning of the LCLS-II hard X-ray FEL is starting at SLAC National Accelerator Laboratory. This facility will ultimately accelerate electrons to 8 GeV, with beams of 375 kW at 1 MHz. At such high-powers, errant beams will need to be detected very fast -200 μs- to limit exposure and to protect beam-line and safety components. Currently, LCLS-I uses ion chambers both as Point Beam Loss Monitors (PBLM) by collimators, dumps, septa, etc., and also as Long Beam Loss Monitors (LBML) that provide detection coverage in extended areas where the accelerator enclosure is not sufficiently thick to shield full beam losses. But due to the finite ion mobility and related screening effects, ion chambers are not fast enough, and their response would not be linear at high charge rates. LCLS-II will use synthetic mono-crystalline diamond chips as PBLMs, as those offer nanosecond time resolution due to the high mobility of holes generated in the valence band by charged particles. LBLMs will be 200 m-long optical fibers, with photomultipliers to detect Cerenkov photons produced by charged particles in the fibers. Use of these technologies requires tests and models to correlate their response to different beam losses. Response functions for these detectors have been developed for the FLUKA Monte Carlo code. After benchmarking the models, these have been applied to place PBLMs at locations where signal is relatively insensitive to beam-strike uncertainties and sufficiently above electronic noise, while keeping lifetime to radiation-damage long. Also, topologies where found were one PBLM can protect several components, resulting in cost reductions. As for LBLMs, the existing model helps scale signals for different beam loss configurations as a function of the fiber position.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB102

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paper received ※ 14 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPRB104

Improvements in Long-Term Orbit Stability at NSLS-II

feedback, operation, controls, storage-ring

4070

Y. Hidaka, A. Caracappa, Y. Hu, B. Podobedov, R.M. Smith, Y. Tian, G.M. Wang
BNL, Upton, Long Island, New York, USA

Funding: The study is supported by U.S. DOE under Contract No. DE-SC0012704.
We report our latest efforts to further improve long-term orbit stability at NSLS-II, on top of what is already provided by fast orbit feedback (FOFB) system. A DC local bump generation program, only utilizing RF beam position monitors (BPM) and compatible with FOFB, was first implemented and deployed in operation successfully, allowing on-demand fine adjustments of beamline source positions and angles. Then we introduced a simple feedback version that performs these bump corrections automatically as needed to maintain the sources within in 1 um/urad for select beamlines. In addition, an RF frequency feedback was also implemented to improve stability for 3-pole wigglers and bending magnet users. As a parallel effort, X-ray BPMs were included in a local feedback system to stabilize photon beam motion for several ID beamlines. However, this feedback scheme is not transparent to FOFB, and suspected to be the source of occasional saturation of fast corrector strength. As an alternative solution, the local bump program and its feedback version has been recently upgraded to include bumps with X-ray BPMs and in operation since April 2019.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPRB104

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paper received ※ 19 May 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS056

New Undulator and Front End for XAIRA Beamline at ALBA

undulator, vacuum, storage-ring, synchrotron

4231

J. Campmany, J. Marcos, V. Massana
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain

A new microfocus beamline for macromolecular crystallography, XAIRA, is being built at ALBA synchrotron light source. The light source for this new beamline is an in-vacuum undulator that can reach the spectrum range from 4 keV up to 20 keV. The in-vacuum undulator was terndered in 2018 and awarded to Kyma-RI consortium, and will be delivered to ALBA in November 2019. The Front End has been designed accordingly. It was tendered in 2018 and awarded to FMB. It will be delivered along second semester of 2019. In this paper we present the ID and FE designs.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS056

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paper received ※ 11 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS064

Sub-Picosecond X-Ray Streak Camera using High-Gradient RF Cavities

electron, cathode, gun, simulation

4256

F. Toufexis, V.A. Dolgashev
SLAC, Menlo Park, California, USA

Funding: This project was funded by U.S. Department of Energy under Contract No. DE-AC02-76SF00515.
We are developing an ultrafast diagnostic system for X-ray beams from Synchrotron Light Sources and Free-Electron Lasers. In this system, the X-ray beam is focused on the photocathode of a high-gradient radio-frequency cavity that accelerates the photo-emitted electrons to a few MeV while preserving their time structure. The accelerated electron beam is streaked by radio-frequency deflectors and then imaged on a screen. This approach will allow orders of magnitude improvement in time resolution over traditional streak cameras and could potentially enable time-resolved diagnostics of sub-100 fs X-ray pulses. We present preliminary beam dynamics simulations of this system and discuss the implementation.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS064

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paper received ※ 11 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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THPTS073

Radiation Damage to Undulator Electronics at an Electron Accelerator

radiation, electron, electronics, neutron

4285

T.Y. Chung, C.-H. Chang, A.Y. Chen, Y.W. Chen, J.C. Huang, J.C. Jan
NSRRC, Hsinchu, Taiwan

Experience gained from commissioning and operation of three elliptical polarization undulators (EPU) at the TPS taught us that undulator driving systems can behave erratically following a beam dump or loss. In this work, we discuss possible harmful radiation sources in a storage ring and analyse the effect of lack of electronic component radiation resistance in the system. According to measurements of spatial radiation distribution at the TPS, we propose solutions and an improved design for Phase-II EPUs.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS073

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paper received ※ 19 April 2019 paper accepted ※ 23 May 2019 issue date ※ 21 June 2019

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THPTS093

Synchrotron Radiation Heating of the Helical Superconducting Undulator

vacuum, synchrotron, radiation, synchrotron-radiation

4328

J.C. Dooling, R.J. Dejus, V. Sajaev
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02- 06CH11357.
A helical superconducting undulator (HSCU) was installed in the Advanced Photon Source (APS) Storage Ring (SR) during the January 2018 maintenance period. Shortly after the reintroduction of beam into the SR in late January, higher than expected heating was observed in the cryogenic cooling system. Steering the electron beam orbit in the upstream dipole provided reduction of the amount of synchrotron radiation reaching into the HSCU and allowed the device to properly cool and operate. Modeling the HSCU geometry with MARS shows the importance of Compton Scattering in transferring synchrotron photons with energies in the range of 10-100 keV through the vacuum chamber into the HSCU magnet pole and winding regions. Simulations carried out using MARS with EGS5 enabled indicate a rapid increase in transfer efficiency from the chamber wall to the HSCU with photon energy. Realistic spectral distributions of synchrotron photons are employed as input to MARS for several bending magnet field strengths.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-THPTS093

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paper received ※ 12 May 2019 paper accepted ※ 22 May 2019 issue date ※ 21 June 2019

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FRXXPLM2

Magnet Design for Siam Photon Source II

quadrupole, sextupole, vacuum, multipole

4361

P. Sunwong, P. Klysubun, T. Phimsen, S. Prawanta, P. Sudmuang
SLRI, Nakhon Ratchasima, Thailand

Siam Photon Source II project has been approved and detailed technical design of the accelerator system is currently in progress. The Double Triple Bend Achromat (DTBA) lattice is implemented in the storage ring design for low emittance and more space for insertion devices. Magnets with moderate to high field requirements have been designed, including combined function magnet with the field gradient of 27.1 T/m, quadrupole magnets with the field gradient up to 60 T/m and multifunction sextupole magnets. This work presents the magnet requirement and specification, design concept, recent simulation results and analysis of the magnetic field quality. A plan for prototype development is also discussed.

Slides FRXXPLM2 [1.475 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-FRXXPLM2

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paper received ※ 15 May 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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FRYPLM2

Lasers for Novel Accelerators

laser, plasma, electron, operation

4385

L.A. Gizzi, P. Koester, L. Labate, G. Toci, M. Vannini
INO-CNR, Pisa, Italy
F. Mathieu
LULI, Palaiseau, France
Z. Mazzotta
ARCNL, Amsterdam, The Netherlands
Z. Mazzotta
Ecole Polytechnique, Palaiseau, France

Significant progress has been made over the last decade in optical laser performance including repetition rate, average and peak power, and laser-system footprint making these systems attractive for many applications including novel accelerators. Most novel acceleration schemes require high-power lasers. The talk will present drive laser requirements for current novel accelerator schemes, industry plans to meet these requirements, and the future for high-power lasers.

Slides FRYPLM2 [32.406 MB]

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2019-FRYPLM2

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paper received ※ 08 April 2019 paper accepted ※ 21 May 2019 issue date ※ 21 June 2019

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