IPAC2018 - List of Keywords (radiation)

Paper	Title	Other Keywords	Page
MOZGBD3	Performance of the First LCLS-II Cryomodules: Issues and Solutions	cavity, cryomodule, HOM, operation	34
	N. Solyak, E. Cullerton, J. Einstein-Curtis, E.R. Harms, B.D. Hartsell, J.P. Holzbauer, T.N. Khabiboulline, A. Lunin, Y.M. Pischalnikov, R.P. Stanek, G. Wu Fermilab, Batavia, Illinois, USA O. Napoly CEA/DSM/IRFU, France
	LCLS-II 4 GeV linac is on the middle production stage. Linac contains 40 cryomodules of 1.3 GHz and 3 cryomodules of 3.9 GHz, including spares. Fermilab and JLAB share responsibility for cryomodule design, assembly and test. Paper will overview the performance of the cryomodules it the tests, lessons learned and modifications in design to improve performance.
	Slides MOZGBD3 [8.630 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBD3
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MOZGBD5	A Proposal for Coherent Hard X-Ray Generation Based on Two-Stage EEHG	FEL, electron, laser, linac	38
	Z.T. Zhao, J.H. Chen, C. Feng, Z. Wang, K.Q. Zhang SINAP, Shanghai, People's Republic of China
	A two stage echo-enabled harmonic generation (EEHG) scheme to produce coherent hard X-rays is presented. Electron bunchs of quite different lengths are separately used in each stage of EEHG and a monochromator is employed to purify the radiation from the first stage for seeding the second one. Theoretical analysis and 3D simulations show that the proposed scheme can generate fully coherent hard X-ray pulses directly from a conventional UV seed laser.
	Slides MOZGBD5 [7.330 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBD5
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MOZGBE5	Results on the FCC-hh Beam Screen at the KIT Electron Storage Ring KARA	photon, electron, experiment, vacuum	55
	L.A. Gonzalez, V. Baglin, P. Chiggiato, C. Garion, M. Gil Costa, 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 3 FCC-hh beam-screen (BS) prototypes has been carried out with the aim of testing them at room temperature at the Karlsruhe Institute of Technology (KIT) 2.5 GeV electron storage ring KARA (KArlsruhe Research Accelerator). The 3 BS prototypes will be 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 the one foreseen for the 50+50 TeV FCC-hh proton collider. Each of the 3 BS prototypes, 2 m in length, implement a different design feature: 1) baseline design (BD), with electro-deposited copper and no electron-cloud (EC) mitigation features; 2) BD with set of distributed cold-sprayed anti-EC clearing electrodes; 3) BD with laser-ablated anti-EC surface texturing. We present here the results obtained so far at BESTEX and the comparison with extensive montecarlo simulations of the expected outgassing behavior under synchrotron radiation. The information herein only reflects the views of its authors and the European Commission is not responsible for any use that may be made of the information.
	Slides MOZGBE5 [4.318 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOZGBE5
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MOPMF036	FCC-ee Hybrid RF Scheme	cavity, HOM, impedance, operation	173
	Sh. Gorgi Zadeh, U. van Rienen Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany R. Calaga, F. Gerigk CERN, Geneva, Switzerland
	Funding: Research supported by the FCC design study For FCC-ee, the range of beam energies and beam currents is large between each mode of operation, all scaled to an available 50 MW maximum power per beam. The two limiting scenarios for the RF system design are at low energy (45 GeV) with high beam current (1.45 A) and the highest energy (182.5 GeV) with a radiation loss reaching 8.92 GeV per turn. In this paper, RF staging with a hybrid scheme using both 400 MHz and 800 MHz is proposed to mitigate the requirements on the two extremes. Relevant comparisons are made with respect to using only a single frequency for all modes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF036
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MOPMF068	Quantum Excitation due to Classical Beamstrahlung in Circular Colliders	collider, photon, simulation, emittance	281
	M.A. Valdivia García, D. El Khechen, K. Oide, F. Zimmermann CERN, Geneva, Switzerland
	In the collisions of proposed future circular colliders, like FCC-ee and CEPC, the beamstrahlung regime is classical, i.e. with an "Upsilon parameter" much smaller than 1. In the classical regime, for a constant electromagnetic field a simple relation exists between the average photon energy u and the average squared photon energy u², which is the same as for standard synchrotron radiation in storage rings. This relation breaks down, however, if the electromagnetic field is not constant in time and position, as is the case for a beam-beam collision. We derive an analytical expression for u²/u², considering the case of Gaussian-bunch collisions with crossing angle (and possibly crab waist). We compare our result with the photon energies obtained in beam-beam simulation for FCC-ee at beam energies of 45.6 GeV and 175 GeV, using the two independent codes BBWS and Guineapig. Finally, we re-optimize the FCC-ee parameters of a possible mono-chromatization scheme for direct Higgs production at 125 GeV, derived previously, by applying the refined expression for the rms photon energy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMF068
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MOPMK003	Energy Deposition Studies and Luminosity Evolution for the Alternative FCC-hh Triplet	optics, luminosity, quadrupole, dipole	352
	J.L. Abelleira, E. Cruz Alaniz, A. Seryi, L. van Riesen-Haupt JAI, Oxford, United Kingdom J.L. Abelleira, E. Cruz Alaniz, L. van Riesen-Haupt University of Oxford, Oxford, United Kingdom
	Funding: Work supported by EuroCircol, EU's Horizon 2020 grant No 654305 & STFC grant to the John Adams Institute The international Future Circular Collider (FCC) study comprises the development of a new scientific structure in a tunnel of 100 km. This will allow the installation of a proton collider with a centre of mass energy of 100 TeV, called FCC-hh. An alternative design of the final focus triplet for the FCC-hh has been developed in parallel to the alternative one, and adapted to the constraint of a free length (L*) of 40 m. We discuss in this paper the energy deposition issues as well as the luminosity evolution for two different optics choices: round and flat beams.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPMK003
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MOPML011	Liquid Cluster Ion Beam Processing of Transition Metal Films	vacuum, acceleration, target, experiment	415
	D. Shimizu, H. Ryuto, M. Takeuchi, D. Yamamoto Kyoto University, Photonics and Electronics Science and Engineering Center, Kyoto, Japan
	The irradiation effects of cluster ion beams are characterized by the high-density collision of molecules that comprise the clusters against a target. According to molecular dynamics calculations, the local temperature of the colliding cluster and the surface of the target are expected to increase to several thousand K. The enhancement of the chemical interactions between the molecules in the colliding clusters and the atoms on the target surface is expected, if polyatomic molecules, such as ethanol and acetone, are used for the source material of the cluster. So, the irradiation effects of the polyatomic liquid cluster ion beams on transition metal films have been studied to examine the possibility of utilizing the liquid cluster ion beam technique for the processing of transition metal films. The transition metal films were formed by magnetron sputtering. The liquid clusters were produced by the adiabatic expansion method and ionized by electron ionization. The sputtering yields of transition metal films induced by liquid cluster ions are discussed.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML011
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MOPML021	Shorter Treatment Time by Intensity Modulation with a Betatron Core Extraction	betatron, extraction, proton, synchrotron	439
	M. G. Pullia, E. Bressi, G.M.A. Calvi, M. Donetti, L. Falbo, S. Foglio, V. Lante, A. Parravicini, C. Priano, E. Rojatti, S. Savazzi, C. Viviani CNAO Foundation, Pavia, Italy
	The CNAO (National Center for Oncological Hadrontherapy) main accelerator is a synchrotron capable to accelerate carbon ions up to 400 MeV/u and protons up to 250 MeV. Three treatment rooms are available and are equipped with horizontal beam lines; one of the treatment rooms also features a vertical treatment line to allow additional treatment ports. All of the beamlines are equipped with an active beam scanning system for dose delivery. With such a dose distribution technique, particles are sent to different depths by changing the energy from the synchrotron and are moved transversally by means of two scanning magnets. The number of particles to be deposited in each position varies strongly within the same iso-energetic layer. Part of the dose needed in a given position is in fact delivered by particles directed to deeper layers. In order to maintain the required precision on the number of particles delivered to each spot, the intensity is reduced when spots that require low number of particles are present in a layer. A method to shorten the irradiation time based on variable intensity within the same layer is presented that works also with a betatron based extraction scheme.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML021
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MOPML022	Development of Travelling Wave Accelerating Structure for a 10 MeV E-Linac	electron, bunching, linac, simulation	443
	J.H. Yang, Y. Yang CIAE, Beijing, People's Republic of China G. Han China Institute of Atomic Energy, Beijing, People's Republic of China
	Electron irradiation processing is a vital application field of nuclear technology application. China Institute of Atomic Energy (CIAE) developed several 10 MeV high power electron irradiating accelerator successfully, promoting the development of high energy high power irradiating accelerator technology and electron irradiation processing in China. The paper introduced the development of a 10 MeV travelling wave accelerating tube. The tube operates at 2856 MHz in 2π/3 mode. The SUPERFISH and PARMELA are used for the physical design. Several methods are used for microwave parameter measurement and tuning. The high power test shows the beam energy is 10.3 MeV and average beam power is 24.3 kW.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML022
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MOPML028	Accelerator Machines and Experimental Activities in the ENEA Frascati Particle Accelerators and Medical Application Laboratory	experiment, proton, electron, linac	460
	M. Vadrucci, A. Ampollini, G. Bazzano, F. Borgognoni, P. Nenzi, L. Picardi, C. Ronsivalle, V. Surrenti, E. Trinca ENEA C.R. Frascati, Frascati (Roma), Italy
	Funding: Regione Lazio - TOP IMPLART Project In the ENEA Frascati research center the APAM (Particle Accelerators and Medical Application) laboratory is devoted to the development of particle accelerators for medical applications. Two main facilities are operational. The TOP-IMPLART proton accelerator is a pulsed fully linear machine aimed at active intensity modulated proton therapy with a final energy of 150 MeV. The machine offers two beam extraction points: one at 3-7 MeV, on a vertical line, and the other one at 35 MeV, the maximum energy currently available, with a pulse current up to 35 μA, on the horizontal line. The REX (Removable target Electron X-ray) source consists of an electron standing wave LINAC generating a beam in the energy range of 3 to 5 MeV with a pulsed current of 0.2 A. This source can generate Bremsstrahlung X-ray beams using suitable converters (Pb, W, Ta). This paper describes the experimental results of satellite activities performed in these facilities in the fields of biology, dosimetry, electronics, PIXE spectroscopy and preservation of cultural heritage manufacts.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML028
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MOPML039	Comparison of Two Types of Steerers Applied in Proton Therapy Gantry	quadrupole, proton, simulation, superconductivity	488
	Z.F. Zhao, Q.S. Chen, S. Hu, X. Liu, B. Qin, W. Wei HUST, Wuhan, People's Republic of China W. Chen Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People's Republic of China
	A proton therapy project HUST-PTF (HUST Proton Therapy Facility) based on a 250MeV isochronous superconducting cyclotron is under development in Huazhong University of Science and Technology (HUST). Based on the optics design of the gantry, the steering magnets need to be placed in a compact structure, as well as meet the magnetic field requirement with a maximum deflection angle of ±5mrad@250MeV. In the paper, two types of steerers (O-shape and H-shape) were introduced and discussed in detail. The magnetic fringe field interference effects between quadrupoles and steerers were studied by using OPERA/TOSCA code. The result based on the contrastive analysis will give us a valuable reference to choose suitable steerers for proton therapy beamline.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML039
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MOPML043	High Gradient Performance of an S-Band Backward Traveling Wave Accelerating Structure for Medical Hadron Therapy Accelerators	linac, proton, cavity, accelerating-gradient	491
	A. Vnuchenko, C. Blanch Gutiérrez, D. Esperante Pereira IFIC, Valencia, Spain S. Benedetti, N. Catalán Lasheras, A. Grudiev, B. Koubek, G. McMonagle, I. Syratchev, B.J. Woolley, W. Wuensch CERN, Geneva, Switzerland A. Faus-Golfe LAL, Orsay, France T.G. Lucas, M. Volpi The University of Melbourne, Melbourne, Victoria, Australia S. Pitman Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
	The high-gradient performance of an accelerating structure prototype for a medical proton linac is presented. The structure was designed and built using technology developed by the CLIC collaboration and the target application is the TULIP (Turning Linac for Proton therapy) proposal developed by the TERA foundation. The special feature of this design is to produce gradient of more than 50 MV /m in low-β accelerating structures (v/c=0.38). The structure was tested in an S-band test stand at CERN. During the tests, the structure reached over above 60 MV/m at 1.2 μs pulse length and breakdown rate of about 5x10^-6 bpp. The results presented include ultimate performance, long term behaviour and measurements that can guide future optimization.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML043
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MOPML045	Measurement of Displacement Cross-Section for Structural Materials in High-Power Proton Accelerator Facility	experiment, proton, target, cryogenics	499
	S.I. Meigo, S.H. Hasegawa, H.I. Hiroki, H. Hiroki, Y. Iwamoto, F.M. Maekawa JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan T. Ishida, S. Makimura, T. Nakamoto KEK, Ibaraki, Japan Y. Makoto J-PARC, KEK & JAEA, Ibaraki-ken, Japan
	As the increase of beam power of hadron accelerators, the damage to target material is essential. For estimation of damage such as target material used at the facility, displacement per atom (DPA), calculated by the particle flux multiplied displacement cross-section with cascade mode, is widely employed as an index of the damage. Although the DPA is employed as the standard, the experimental data of displacement cross-section are scarce for a proton in the energy region above 20 MeV. A recent study reports that the displacement cross section of tungsten has 8 times difference among the calculation models. Therefore, experimental data of the displacement cross-section is crucial. The displacement cross-section can be obtained by observing the change of resistivity of the sample cooled by GM cooler to sustain the damage. The sample is placed in the vacuum chamber placed at upstream of the beam dump for 3 GeV and 30 GeV synchrotrons in J-PARC, where the sample will be irradiated by the proton in the energy range between 0.4 and 30 GeV. In the vast energy range, the displacement cross-section can be obtained for the proton, which will help to improve the damage estimation of the target material.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML045
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MOPML048	Design Study of PM Dipole for ILC Damping Ring	dipole, permanent-magnet, damping, operation	505
	Y. Iwashita Kyoto ICR, Uji, Kyoto, Japan N. Terunuma KEK, Ibaraki, Japan
	Dipole magnet using permanent magnet technology is under investigation for ILC cost reduction. It can reduce cost of electricity of coil excitation and cooling water pump, thick electric cabling and water piping, power supply, and their maintenance cost. The structure and the field adjustment scheme will be discussed.
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MOPML050	A Massive Open Online Course on Particle Accelerators	target, survey, neutron, synchrotron	512
	N. Delerue, A. Faus-Golfe LAL, Orsay, France M.E. Biagini INFN/LNF, Frascati (Roma), Italy E. Bründermann, A.-S. Müller KIT, Eggenstein-Leopoldshafen, Germany P. Burrows JAI, Oxford, United Kingdom G. Burt Cockcroft Institute, Lancaster University, Lancaster, United Kingdom A. Cianchi Università di Roma II Tor Vergata, Roma, Italy C. Darve, R.A. Yogi ESS, Lund, Sweden V.V. Dmitriyeva, S.M. Polozov MEPhI, Moscow, Russia J. Kvissberg Lund University, Lund, Sweden P. Lebrun JUAS, Archamps, France E. Métral, H. Schmickler, J. Toes CERN, Geneva, Switzerland S.P. Møller ISA, Aarhus, Denmark L. Rinolfi ESI, Archamps, France A. Simonsson Stockholm University, Stockholm, Sweden V.G. Vaccaro Naples University Federico II and INFN, Napoli, Italy
	Funding: European Union H2020 - ARIES Project The TIARA (Test Infrastructure and Accelerator Research Area) project funded by the European Union 7th framework programme made a survey of provision of education and training in accelerator science in Europe highlighted the need for more training opportunities targeting undergraduate-level students. This need is now being addressed by the European Union H2020 project ARIES (Accelerator Research and Innovation for European Science and Society) via the preparation of a Massive Online Open Course (MOOC) on particle accelerator science and engineering. We present here the current status of this project, the main elements of the syllabus, how it will be delivered, and the schedule for providing the course.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML050
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MOPML051	First Performance Calculations for the Very High Energy Electron Radiation Therapy Experiment at PRAE	electron, experiment, proton, photon	516
	A. Faus-Golfe LAL, Orsay, France R. Delorme, Y. Prezado IMNC, Orsay, France V. Favaudon, C. Fouillade, S. Heinrich, A. Mazal, A. Patriarca, P. Poortmans, P. Verrelle Institut Curie - Centre de Protonthérapie d'Orsay, Orsay, France A. Hrybok National Taras Shevchenko University of Kyiv, Radiophysical Faculty, Kiev, Ukraine
	The Platform for Research and Applications with Electrons (PRAE) project aims at creating a multidisciplinary R&D platform at the Orsay campus, joining various scientific communities involved in radiobiology, subatomic physics, instrumentation, particle accelerators and clinical research around a high-performance electron accelerator with beam energies up to 70 MeV and later 140 MeV, in order to perform a series of unique measurements and challenging R&D. In this paper we will report the first optics design and performance evaluations of such a multidisciplinary machine, focusing on Very High Energy Electrons (VHEE) innovative Radiation Therapy (RT) applications in particular by allowing Grid and FLASH methodologies, which are likely to represent a major breakthrough in RT. Functional specifications include beam intensities to produce dose rates from 2 Gy/min to 100Gy/sec, beam sizes with diameters from 0.5 mm to 10 cm or more of homogeneous beams and monitoring devices with accuracy in the order of 1-2% for single or multiple beams and single or multiple fractions in biological and ppreclinical applications. High energies (>140 MeV) would be also needed for GRID therapy.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML051
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MOPML058	Comparison of Water Absorbed Dose for Photons of Linac and Traceability System for Radiotherapy in China	photon, controls, linac, electron	537
	K. Wang, S. Jin, Z. Wang, J. Zhang National Institute of Metrology, Beijing, People's Republic of China
	National Institute of Metrology (NIM) developed the standards of the absorbed dose to water for high-energy photon and electron beams, to support the PSDL and SSDL calibration capability in China. After the measurement of absorbed dose to water for 6, 10, and 25 MV photons of linac, NIM took part the BIPM. RI(I).K6 comparison with the Bureau International des Poids et Mesures (BIPM). The tissue phantom ratio (TPR_20,10) of 6MV and 10MV photons were measured by IBA CC13 chamber and Keithley 6517B with different output dose of the Linac, and also calculated by the dose ratio (D₂0⁄D₁0) with the formula in IAEA TRS-398 report. TPR_20,10 measured directly is 0.3% larger than calculated by the dose ratio D₂0⁄D₁0 . The absorbed dose to water is measured by water calorimeter with the combined standard uncertainty of 0.35%. The discrepancy of absorbed dose to water measured separately by open and sealed vessel is 0.2% at 10MV. The K6 comparison was done, the results reported as ratios of the NIM and the BIPM evaluations (and with the combined standard uncertainties given in parentheses), are 0.9917(60) at 6 MV, and 0.9941(59) at 10 MV. The quality correction factor KQ of usual used chamber was measure directly, and it is 0.3%~0.7% smaller than the data in the IAEA TRS-398 report. The typical chamber-to-chamber variations of the dose obtained with the IAEA TRS-277, TRS-398 and AAPM TG-51 were between 0.2% and 1.0% for the different photon beams. The variations of the dose obtained with IAEA TRS-398 and chambers calibrated directly by megavoltage photons were between 0.1% to 0.8%. The new standard can achieve the traceability of water absorbed dose for MV photons and will significantly reduce the uncertainty of ion chamber calibrations for Chinese radiotherapy centers.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML058
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MOPML059	Precise Beam Delivery for Proton Therapy with Dynamic Energy Modulation	proton, target, MMI, controls	540
	O. Actis, A. Mayor, D. Meer, D.C. Weber PSI, Villigen PSI, Switzerland D.C. Weber University of Zurich, University Hospital, Zurich, Switzerland
	Gantry 2 at PSI is a Pencil Beam Scanning (PBS) cyclotron based proton therapy system. PBS proved to be an effective treatment method for static tumors but for mobile targets (e.g lung) organ motion interferes with beam delivery lowering the treatment quality. A method to mitigate motion effects is to re-scan the treatment volume multiple times. The downside of re-scanning is the increase of treatment time due to high number of energy switches and magnet initializations (ramping) between scans. Our current re-scanning implementation is performed with a decreasing energy sequence and takes about 6s/scan thanks to fast energy switching of 100ms. Ramping adds 8s more leading to a treatment time of >60s. We developed beam line settings for reverse energy sequence and removed the full ramping between scans. This dynamic beam delivery leads to non-negligible beam position errors of >1.5mm which we compensate by field specific corrections. Using a patient file we proved that our novel re-scanning concept doubles the treatment efficiency. Using in-house developed measurement equipment we obtained a precision of <0.5mm in position and <1mm in range which fulfills all clinical requirements.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML059
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MOPML063	In Situ Observations of Blistering of a Metal Irradiated with 2 MeV Protons	proton, neutron, target, experiment	553
	S.Yu. Taskaev, D.A. Kasatov, A.N. Makarov, I.M. Shchudlo BINP SB RAS, Novosibirsk, Russia A. Badrutdinov, Y. Higashi, T. Miyazawa OIST, Onna-son, Okinawa, Japan T.A. Bykov Budker INP & NSU, Novosibirsk, Russia S.A. Gromilov Nikolaev IIC, Novosibirsk, Russia Ya.A. Kolesnikov, A.M. Koshkarev, E.O. Sokolova NSU, Novosibirsk, Russia H. Sugawara KEK, Ibaraki, Japan
	Funding: This study was carried out with a grant from the Russian Science Foundation (project No. 14-32-00006-P) with the support of the Budker Institute of Nuclear Physics and Novosibirsk State University. A vacuum-insulated tandem accelerator was used to observe in situ blistering during 2-MeV proton irradiation of metallic samples to a fluence of up to 6.7 10²⁰ cm². Samples consisting of copper of different purity, tantalum, and tantalum-copper compounds were placed on the proton beam path and forced to cool. The surface state of the samples was observed using a CCD camera with a remote microscope. Thermistors, a pyrometer, and an infrared camera were applied to measure the temperature of the samples during irradiation. After irradiation, the samples were analyzed on an X-ray diffractometer, laser and electron microscopes. The present study describes the experiment, presents the results obtained and notes their relevance and significance in the development of a lithium target for an accelerator-based neutron source, for use in boron neutron capture therapy of cancer.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-MOPML063
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TUYGBD4	Beam Loss Background and Collimator Design in CEPC Double Ring	detector, scattering, background, simulation	632
	S. Bai, J. Gao, H. Geng, D. Wang, Y. Wang, C.H. Yu, Y. Zhang IHEP, 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. Radiative Bhabha scattering and Beamstrahlung effects are dominant mechanism of the beam induced backgrounds at CEPC due to the beam lifetime. In this paper, we evaluated the beam loss background in simulation and designed a series of collimators to suppress the radiation level on the machine and the detector.
	Slides TUYGBD4 [0.791 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUYGBD4
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TUPAF015	Preliminary Test Results of the First ESS Elliptical Cryomodule Demonstrator	cavity, cryomodule, cryogenics, vacuum	691
	F. Peauger, C. Arcambal, S. Berry, P. Bosland, E. Cenni, G. Devanz, T. Hamelin, O. Piquet, B. Renard, P. Sahuquet, T. Trublet CEA/DRF/IRFU, Gif-sur-Yvette, France C. Darve ESS, Lund, Sweden P. Michelato INFN/LASA, Segrate (MI), Italy G. Olivier IPN, Orsay, France J.P. Thermeau Laboratoire APC, Paris, France
	Two ESS elliptical cavities cryomodule prototypes are being developed and will be tested at CEA Saclay before starting the series production. This paper presents the preliminary test results of the first medium beta cavities cryomodule demonstrator M-ECCTD. The measurements of the cryogenic performances at 80 K and 2 K of the different cryomodule components and circuits are given. The first RF test results performed at low power are also reported.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF015
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TUPAF023	The Beamlines of the CERN East Area Renovation Project	target, secondary-beams, experiment, operation	717
	J. Bernhard, M. Bonnet, Q. Bouirek, D. Brethoux, B.D. Carlsen, A. Ebn Rahmoun, J. Etheridge, S. Evrard, L. Gatignon, E. Harrouch, M. Lazzaroni, M. Van Dijk, A. Watrigant CERN, Geneva, Switzerland
	The East Area at the Proton Synchrotron is one of CERN's longest running facilities for experiments, beam tests, and irradiations with a successful history of over 55 years. The facility serves more than 20 user teams for about 200 days of running each year and offers mixed secondary hadron, electron and muon beams of 0.5 GeV/c to 10 GeV/c. In addition, the primary proton beam or ion beam is transported to the irradiation facilities CHARM and IRRAD. Due to the steadily high user demand, the CERN management approved an upgrade and renovation of the facility to meet future beam test and physics requirements. New beam optics will assure a better transmission and purity of the secondary beams, now also with the possibility of highly pure electron, hadron or muon beams. The upgrade includes a pulsed powering scheme with energy recovering power supplies and new magnets, reducing both power and cooling requirements. Together with the building consolidation, this results in a considerably lower energy consumption. The renovation phase is scheduled during the technical stops between 2018 and 2020. We will give an overview of the project scope including upgrades and future beams.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF023
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TUPAF074	Preliminary Modelling of Radiation Levels at the Fermilab PIP-II Linac	linac, proton, GUI, booster	898
	L. Lari, C.M. Baffes, S.J. Dixon, N.V. Mokhov, I.L. Rakhno, I.S. Tropin Fermilab, Batavia, Illinois, USA F. Cerutti, L.S. Esposito, L. Lari CERN, Geneva, Switzerland
	PIP-II is the Fermilab's flagship project for providing powerful, high-intensity proton beams to the laboratory's experiments. The heart of PIP-II is an 800-MeV superconducting linac accelerator. It will be located in a new tunnel with new service buildings and connected to the present Booster through a new transfer line. To support the design of civil engineering and mechanical integration, this paper provides preliminary estimation of radiation level in the gallery at an operational beam loss limit of 0.1 W/m, by means of Monte Carlo calculations with FLUKA and MARS15 codes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF074
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TUPAF083	SIS100 Tunnel Design and Civil Construction Status	site, status, experiment, shielding	927
	C. Omet, J. Falenski, H. Kisker, K. Konradt, P.J. Spiller GSI, Darmstadt, Germany A. Fischer FAIR, Darmstadt, Germany
	As the FAIR Project is proceeding, building designs have been frozen and the according work packages tendered. For the future FAIR main driver accelerator, SIS100, the 1.1 km long accelerator tunnel "T110", has been planned 17 m deep under ground. In this article, environmental boundary conditions, the chosen layout and the current status of civil construction is presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF083
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TUPAF085	Status of Link Existing Facility Project for FAIR	linac, shielding, operation, synchrotron	934
	J. Stadlmann, C. Omet, A. Schuhmann, P.J. Spiller GSI, Darmstadt, Germany
	The project "Link existing Facility", or GaF (GSI Anbindung an FAIR), is an important subproject of the overall FAIR facility. In order to serve as injector for SIS100, the main accelerator of FAIR, the existing GSI synchrotron SIS18 is undergoing an upgrade program leading to about 100 times higher beam intensities. Especially the foreseen operation with 4 GeV Protons with up to 5·10¹² protons per second increases the radiation protection requirements to such an extent that the existing radiation protection measures are no longer sufficient. The project consists of 78 individual measures. The four most substantial activities are the construction of a table-like structure to carry additional shielding. The creation of an opening and a first part of transfer tunnel for the beamlines towards the future FAIR campus. The preparation for the building, beam dump and connection of the FAIR proton injector. The incorporation of state-of-the-art radiation- and fire-protection measures into the present facilities including the a new technical building to house technical infrastructure. We report on the project status which is foreseen to finish mid-2018.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAF085
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TUPAK013	Geant4 Simulation of Radiation Effect on the Deflector of Extraction System in HUST SCC250	septum, proton, neutron, simulation	990
	S. Hu, K. Fan, L.X.F. Li, Z.Y. Mei, Z.J. Zeng, L.G. Zhang HUST, Wuhan, People's Republic of China
	China has payed extensive attention to the development of proton therapy in recent years. When design a compact, high energy superconducting cyclotron for proton therapy， radiation effect induced by beam losses is a crucial consideration. Since the proton beam is extracted out of HUST SCC250 by electrostatic deflectors, the fierce interaction between proton beam and the deflector septum is the main cause of beam losses, which will bring about radiation effect leading to activation and coil quench. This paper presents simulation results of radiation effect by utilizing Geant4 Monte Carlo code. The energy depositions of proton beam in various septum materials are compared. Meanwhile, the yields, the ener-gy and angular distributions of secondary particles are investigated. Those simulation results based on radiation effect will provide us with valuable implications for the design of this superconducting cyclotron.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAK013
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TUPAL021	Evaluation of Activated Nuclides Due to Secondary Particles Produced in Stripper Foil in J-PARC RCS	proton, experiment, neutron, target	1048
	M. Yoshimoto, S. Kato, M. Kinsho, K. Okabe, P.K. Saha, K. Yamamoto JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
	Multi-turn charge-exchange beam injection is key technique to achieve the high intensity proton beam accelerators. In the J-PARC RCS, 400MeV H⁻ beams from the LINAC are converted to H⁺ beam with the stripper foils, and then injected into the ring. The stripper foil is irradiated by not only the injecting H⁻ beams but also the circulating H⁺ beams. The high energy and high power beam irradiation into the foil induces the nuclear reactions, and generated secondary neutrons and protons. These secondary particles causes high residual does around the stripper foil. Now, to identify species of secondary particles and to identify energies and emission angles, activation analysis method using the sample pieces is considered. In this presentation, we report the result of the evaluation of this activation analysis with PHITS codes.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL021
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TUPAL045	Towards Operational Scalability for H⁻ Laser Assisted Charge Exchange	laser, experiment, cavity, operation	1110
	S.M. Cousineau, A.V. Aleksandrov, T.V. Gorlov, Y. Liu, M.A. Plum, A. Rakhman, A.P. Shishlo ORNL, Oak Ridge, Tennessee, USA D.E. Johnson, S. Nagaitsev Fermilab, Batavia, Illinois, USA M.J. Kay UTK, Knoxville, Tennessee, USA
	The experimental development of H⁻ laser assisted charge exchange, a.k.a. laser stripping, has been ongoing at the SNS accelerator since 2006 in a three-phase approach. The first two phases associated with proof-of-principle and proof-of-practicality experiments have been successfully completed and demonstrated >95% H⁻ stripping efficiency for up to 10 us. The final phase is a proof-of-scalability stage to demonstrate that the method can be deployed for realistic beam duty factors. The experimental component of this effort is centered on achieving high efficiency stripping through the use of a laser power amplification scheme to recycle the macropulse laser light at the interaction point of the H⁻ stripping. Such a recycling cavity will be necessary for any future operational laser stripping system with at least millisecond duration H⁻ pulses. A second component of the proof-of-scalability phase is to develop a conceptual design for a realistic laser stripping scheme. The status of these efforts and challenges associated with deploying the recycling cavity into the laser stripping experiment will be described in this talk.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL045
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TUPAL047	Strain Measurement in the Recent SNS Mercury Target with Gas Injection	target, injection, proton, neutron	1117
	Y. Liu, W. Blokland, C.D. Long, S.N. Murray, B.W. Riemer, R.L. Sangrey, M. W. Wendel, D.E. Winder ORNL, Oak Ridge, Tennessee, USA
	Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE. High-radiation-tolerant fiber-optic strain sensors were recently developed to measure the transient proton-beam-induced strain profiles on the mercury target vessel at the Spallation Neutron Source (SNS). Here we report the strain measurement results and radiation-resistance performance on the latest SNS mercury target vessel equipped with helium gas injection. The results have demonstrated the efficacy of gas injection to reduce the cyclic stress on the target module.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL047
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TUZGBF1	Superconducting Gantry for Carbon-Ion Radiotherapy	superconducting-magnet, quadrupole, dipole, MMI	1232
	Y. Iwata, T. Furukawa, Y. Hara, S. Matsuba, T. Murakami, K. Noda, N. S. Saotome, S. Sato, T. Shirai NIRS, Chiba-shi, Japan N. Amemiya Kyoto University, Kyoto, Japan H. Arai, T. Fujimoto AEC, Chiba, Japan T.F. Fujita, K. Mizushima, Y. Saraya National Institute of Radiological Sciences, Chiba, Japan S. Matsuba HSRC, Higashi-Hiroshima, Japan T. Obana NIFS, Gifu, Japan T. Ogitsu KEK, Ibaraki, Japan T. Orikasa, S. Takayama Toshiba, Yokohama, Japan R. Tansho QST-NIRS, Chiba, Japan
	A superconducting magnet gantry has been used at HIMAC in NIRS, transporting beams for carbon ion radiotherapy. A second superconducting gantry, with a different design, is under construction in Yamagata University. This invited talk presents an overview of these gantry designs, their advantages for light ion radiotherapy, their operational experiences, and future perspectives for superconducting radiotherapy gantries.
	Slides TUZGBF1 [26.678 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBF1
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TUZGBF4	The South African Isotope Facility	target, cyclotron, isotope-production, proton	1240
	J.L. Conradie, L.S. Anthony, F. Azaiez, S. Baard, R.A. Bark, A.H. Barnard, P. Beukes, J.I. Broodryk, J.C. Cornell, J.G. De Villiers, H. Du Plessis, W. Duckitt, D.T. Fourie, P.G. Gardiner, M.E. Hogan, I.H. Kohler, J.J. Lawrie, C. Lussi, N.R. Mantengu, R.H. McAlister, J. Mira, K.V. Mjali, H.W. Mostert, C. Naidoo, F. Nemulodi, M. Sakildien, V.F. Spannenberg, G.F. Steyn, N. Stodart, R.W. Thomae, M.J. Van Niekerk, P.A. van Schalkwyk iThemba LABS, Somerset West, South Africa
	iThemba LABS has developed a strategy to respond to the need to expand the research agenda of the facility, as well as to seize the opportunity to exploit the growing global demand for radioisotopes. This strategy will depend on the existing accelerator and isotope production infrastructure, as well as the acquisition of a cyclotron capable of accelerating protons to 70 MeV at beam currents in excess of 700 microampere. This development will be approached in two phases: Phase 1 will include the migration of the existing radioisotope production from the separated-sector cyclotron (SSC) to a new 70 MeV cyclotron. This rearrangement will increase the isotope production capability and also free up the SSC for research. In phase 2, beams of artificial isotopes will be produced at energies up to 5 MeV/nucleon to allow iThemba LABS to expand its research capabilities to new frontiers. The various different aspects of the proposed project will be discussed.
	Slides TUZGBF4 [23.489 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUZGBF4
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TUPMF007	Cryogenic Testing and Initial Performance of a Helical Superconducting Undulator at the APS	vacuum, undulator, cryogenics, operation	1260
	J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, M. Kasa, I. Kesgin, 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. A helical superconducting undulator (HSCU) has been installed and is presently operational at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). We describe the final assembly and cryogenic test program which led to successful operation, representing the culmination of a two-year development effort. Details of the cryostat and cryogenic system design are presented along with as-installed performance data and a comparison with design expectations.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF007
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TUPMF022	Electron Beam Scanning in the Delta-Type Undulators for Sirius	undulator, electron, polarization, storage-ring	1300
	A. B. da Cruz, L. Liu LNLS, Campinas, Brazil
	We report on simulation studies to analyze the possibility of scanning the electron beam, and not scanning the sample, in CDI experiments using a Delta-Type undulator in the 3GeV Sirius electron storage ring presently under construction at LNLS. This would allow much faster scans in diffraction limited storage rings such as Sirius. We study displaced beam trajectories through the undulators and analyze the effects on the emitted radiation. It is possible to show that displacements on the order of ± 500 micrometers around the center will introduce variations in the radiation spectrum that are less that 1 per cent and thus acceptable for Coherent Diffraction Imaging experiments.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF022
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TUPMF051	Generating Ultrashort X-Ray Pulse in a Diffraction-Limed Storage Ring by Phase-Merging Enhanced Harmonic Generation with Normal Modulator	bunching, laser, electron, undulator	1371
	W. Liu, Y. Jiao IHEP, Beijing, People's Republic of China
	In recent years, the study of ultrafast processes has increased the demand for ultrashort pulses. The duration of the synchrotron radiation pulse is generally in the range of 10-100 ps, which cannot be used in the experiments of studying the ultrafast process. Thus it is interesting to explore a way of obtaining sub-picosecond radiation pulses in storage ring light sources. The phase-merging enhanced harmonic generation (PEHG) scheme using a transverse gradient undulator as the modulator can be used to generate coherent radiation at high harmonic, which is very suitable for the generating ultrashort pulses in a diffraction-limed storage ring (DLSR). This paper presents a new PEHG modulation scheme, using a normal undulator as the modulator. This scheme is technically easier to be realized in a DLSR. Simulation is performed to demonstrate the effectiveness of this method.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF051
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TUPMF055	Phase Matching Application in Hard X-Ray Region of HEPS	undulator, brilliance, electron, photon	1386
	X.Y. Li, Z. Duan, Y. Jiao, S.K. Tian IHEP, Beijing, People's Republic of China
	For the 6 meters long straight-section of HEPS, a double collinear double-cryogenic permanent magnet undulator(CPMU) structure is designed for high energy photon users to achieve higher brightness. Angular profiles of radiation produced by the double undulator configuration has been derived analytically. The efficiency of phase shifter on improving the brightness of double-CPMU is therefore evaluated with the beam energy spread is taken into account.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF055
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TUPMF079	An Option to Generate Seeded FEL Radiation for FLASH1	FEL, electron, laser, undulator	1448
	V. Grattoni, R.W. Aßmann, J. Bödewadt, I. Hartl, C. Lechner, B. Manschwetus, M.M. Mohammad Kazemi DESY, Hamburg, Germany W. Hillert, V. Miltchev, J. Roßbach University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany S. Khan, T. Plath DELTA, Dortmund, Germany
	The FLASH free-electron laser (FEL) at DESY is currently operated in self-amplified spontaneous emission (SASE) mode in both beamlines FLASH1 and FLASH2. Seeding offers unique properties for the FEL pulse, such as full coherence, spectral and temporal stability. In this contribution, possible ways to carry the seeded FEL radiation to the user hall are presented with analytical considerations and simulations. For this, components of the sFLASH seeding experiment are used.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPMF079
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TUPML026	Multi-photon Photoemission and Ultrafast Electron Heating in Cu Photocathodes at Threshold	electron, photon, cathode, laser	1593
	J. Bae, L. Cultrera Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA I.V. Bazarov, J.M. Maxson Cornell University, Ithaca, New York, USA S.S. Karkare, H.A. Padmore LBNL, Berkeley, California, USA P. Musumeci, X.L. Shen UCLA, Los Angeles, California, USA
	Funding: U.S. National Science Foundation under award PHY-1549132, the Center for Bright Beams. Operating photocathodes near the photoemission threshold holds the promise of yielding small intrinsic emittance, at the cost of significantly reduced quantum efficiency. In modern femtosecond photoemission electron sources, this requires a very high intensity (10s of GW/cm²) to extract a useful quantity of electrons. At this intensity, the electron occupation function is far from equilibrium and evolves rapidly on sub-ps timescales. Thus, ultrafast laser heating and multiphoton photoemission effects may play a significant role in emission, thereby increasing the minimum achievable emittance. In this work, we use a Boltzmann equation approach to calculate the non-equilibrium occupation function evolution in time for a copper photocathode, yielding a prediction of quantum efficiency and mean transverse energy as a function of input intensity.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML026
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TUPML035	FELs Driven by Laser Plasma Accelerators Operated with Transverse Gradient Undulators	undulator, FEL, electron, laser	1615
	F. Jafarinia, R.W. Aßmann, F. Burkart, U. Dorda, C. Lechner, B. Marchetti, R. Rossmanith, P.A. Walker DESY, Hamburg, Germany A. Bernhard, R. Rossmanith KIT, Karlsruhe, Germany
	Laser Plasma Accelerators produce beams with a significantly higher energy spread (up to a few percent) compared to conventional electron sources. The high energy spread increases significantly the gain length when used for an FEL. In order to reduce the gain length of the FEL the Transverse Gradient Undulators (TGUs) instead of conventional undulators were proposed. In this paper the limits of this concept are discussed using a modified Version of the GENESIS program. Zhirong Huang et al., Phys. Rev. Lett., 109, 204801
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML035
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TUPML054	Microbeam Irradiation System with a Dielectric Laser Accelerator for Radiobiology Research	laser, electron, accelerating-gradient, cavity	1664
	K. Koyama KEK, Ibaraki, Japan Z. Chen The University of Tokyo, Tokyo, Japan T. Takahashi The University of Tokyo, The School of Engineering, Tokyo, Japan M. Uesaka The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
	Funding: This work was supported by KAKENHI (Grant-in-Aid for Scientific Research)15H03595 and partly supported by NIMS Nanofabrication Platform in Nanotechnology Platform Project sponsored by the MEXT, Japan. A laser micro-irradiation (LMI) system is widely used in the field of radiobiology because of its acceptably small size. However, damage in a cell nucleus caused by the LMI system does not necessarily simulate a radiation effect. If the laser of the LMI system is replaced with a small-scale 1MeV-class accelerator such as a dielectric laser accelerator (DLA), experiments might be performed under conditions that are more realistic. The desirable configuration of the DLA for a compact micro-beam irradiation system is that laser pulses are transported to a dielectric structure by single-mode optical fibers and the laser energy is accumulated in an accelerator channel. The long and low-intensity laser pulse of 100 MW/cm², 10ps and a resonator with Q=10⁴ are capable of producing the light intensity of 1 TW/cm². The long laser pulse, i.e., low laser induced damage threshold intensity, decreases the acceleration gradient to about 1/3 of the ultra-short pulse irradiation of 100 fs. The length of the accelerator at long-laser pulse might be within the allowable range of several cm. The resonator scheme is useful only for the sub-relativistic regime because of the acceleration gradient.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPML054
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WEXGBD1	Development of Very Short Period Undulators	undulator, electron, vacuum, factory	1735
	S. Yamamoto KEK, Ibaraki, Japan
	Scientists and engineers at KEK have developed undulator magnets having very short period lengths. Magnet plates 100mm and 152mm long with 4-mm period length have been successfully fabricated. They produce an undulator field of approximately 4kG at a gap of 1.6mm. The magnetic field characterization shows that the undulator field is satisfactory in quality for a very short period undulator. KEK has recently installed a short-period undulator at a 50-MeV linac and observed a first light, and will soon start an experiment using a short-period undulator with laser-accelerated electrons for future table-top XFELs. This invited talk summarizes the current status, and experimental activities and results related to short-period undulators and table-top FELs.
	Slides WEXGBD1 [3.515 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEXGBD1
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WEXGBE3	IBS Studies at BESSY II and MLS	simulation, emittance, scattering, damping	1755
	T. Mertens Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany T. Atkinson, J. Feikes, P. Goslawski, J.G. Hwang, A. Jankowiak, J. Li, D. Malyutin, Y. Petenev, M. Ries, I. Seiler HZB, Berlin, Germany
	Intrabeam Scattering (IBS) effects will become a limiting factor for the attainable emittances and single-bunch currents in future electron storage rings and light sources. IBS studies were performed for BESSY II at the Helmholtz-Zentrum Berlin (HZB) and for the Metrology Light Source (MLS) at the Physikalisch-Technische Bundesanstalt (PTB) to quantify the IBS contributions to equilibrium beam sizes in these machines and make predictions for the BESSY II upgrade project, BESSY VSR. The energy dependence of IBS effects (γ −4 ) makes especially the MLS machine susceptible to IBS effects due to the relatively low energy ranges at which it can be operated (50 MeV-630 MeV). We compare experimental data with simulations and present IBS simulation results for BESSY VSR.
	Slides WEXGBE3 [0.916 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEXGBE3
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WEYGBD2	Status of the Radiation Damage on the European XFEL Undulator Systems	undulator, FEL, operation, electron	1776
	F. Wolff-Fabris, J. Pflüger XFEL. EU, Schenefeld, Germany F. Hellberg Stockholm University, Stockholm, Sweden F. Schmidt-Föhre DESY, Hamburg, Germany
	The European XFEL GmbH is a new X-ray FEL user facility and started lasing in 2017. Three gap movable SASE Undulator Systems are designed to produce FELs with tunable wavelengths from 0.05 to 5.2nm [,]. A total of 91 5-m long undulator segments based on hybrid NdFeB permanent magnet technology were tuned respecting tight specifications. Radiation damage due to machine operation affects the magnetic properties of the segments and the quality of the SASE process. An array of dosimeters based on Radfets [*] and Gafchromic films monitors the absorbed doses in every undulator segment and each SASE system is equipped with a 12mm gap diagnostic undulator (DU) which is magnetically re-measured during machine maintenance weeks. Doses up to 4 kGy have been observed and magnetic field degradation higher than 3% is measured. These results permit to estimate the effects of radiation damage and life expectancy of the Undulator Systems based on the precise K-parameter determination for beam operation. We will present the results of magnetic re-measurements on the Undulator Systems, the details of the effects of radiation damage and future plans to maximize the beam quality and operation. M. Altarelli et al., Tech. Design Rep. DESY 2006-097, July 2007. E. Schneidmiller et al., Eur. XFEL Tech. Rep. TR-2011-006, Sep. 2011. * F. Schmidt-Föhre et al., IPAC-2018 contribution.
	Slides WEYGBD2 [3.670 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBD2
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WEYGBE1	Suppressing CSR Microbunching in Recirculation Arcs	bunching, dipole, lattice, emittance	1784
	C.-Y. Tsai SLAC, Menlo Park, California, USA
	We provide sufficient conditions for suppression of CSR-induced microbunching instability along transport or recirculation arcs. The example lattices include low-energy (∼100 MeV) and high-energy (∼1 GeV) recirculation arcs, and medium-energy compressor arcs. Our studies show that lattices satisfying the proposed conditions indeed have microbunching gain suppressed. Beam current dependencies of maximal CSR microbunching gains are also demonstrated, which should help outline a beam line design for different scales of nominal currents. We expect this analysis can improve future lattice design.
	Slides WEYGBE1 [10.975 MB]
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEYGBE1
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WEPAF005	A Fast Beam Interlock System for the Advanced Photon Source Particle Accumulator Ring	photon, operation, shielding, detector	1815
	J.C. Dooling, M. Borland, K.C. Harkay, R.T. Keane, B.J. Micklich, C. Yao ANL, Argonne, Illinois, USA
	Funding: Work supported by the U.S. Department of Energy, Office of Science, Of- fice of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. A fast beam interlock system for the Advanced Photon Source (APS) Particle Accumulator Ring (PAR) based on the detection of Cerenkov light is proposed for high-charge operations associated with the APS Upgrade (APS-U). Light is generated from lost electrons passing through high-purity, fused-silica fiber optic cable. The cable acts as both radiator and light pipe to a Pb-shielded photomultiplier tube. Results from a prototype installation along the PAR south wall have shown excellent sensitivity, linearity, and reproducibility after 10,000 hours of operation to date with little change in the optical transmission of the fiber. High sensitivity allows more accurate measurement of low-level loss than possible with current monitors. The radiator and detector provide a much faster response than the installed gamma or neutron detectors. A faster, more accurate response to electron loss will be important as we run with higher charge and consider operating at increased energy for APS-U. Initial calibration measurements of the prototype system with radiation monitors for various loss scenarios are discussed. Comparison of the scenarios with simulations are presented.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF005
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WEPAF012	Improvements of NSLS-II X-ray Diagnostic Beamlines	emittance, storage-ring, vacuum, photon	1837
	W.X. Cheng, B. Bacha, B.N. Kosciuk, D. Padrazo Jr BNL, Upton, Long Island, New York, USA
	Funding: Work supported by DOE contract No: DE-SC0012704 There are two X-ray diagnostic beamlines (XDB) developed at NSLS-II storage ring to measure emittance, energy spread, and other machine parameters. The first beamline utilizes a soft bending magnet radiation has been in operation since 2014. The tungsten pinhole originally located in the air had corrosion issue. The beamline has been improved by extending the vacuum to the imaging system. The second X-ray pinhole beamline using three-pole wiggler (TPW) radiation has been constructed and commissioned recently. Energy spread is able to be precisely measured due to large dispersion at the source point. A gated camera is equipped with the new beamline to acquire profiles within one turn. Recent operation experience and beam measurements will be presented in this paper.
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WEPAF035	Coherent Diffraction Radiation Imaging as an RMS Bunch Length Monitor	FEL, target, experiment, detector	1895
	J. Wolfenden, R.B. Fiorito, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom R.B. Fiorito, C.P. Welsch, J. Wolfenden The University of Liverpool, Liverpool, United Kingdom T.H. Pacey, T.H. Pacey UMAN, Manchester, United Kingdom A.G. Shkvarunets UMD, College Park, Maryland, USA
	Funding: This work was supported by the EU under Grant Agreement No. 624890 and the STFC Cockcroft Institute core Grant No. ST/G008248/1. High-resolution bunch length measurement is of the utmost importance for current and future generations of light sources and linacs. It is also key to the optimisation of the final beam quality in plasma-based acceleration. We present progress in the development of a novel RMS bunch length monitor based on imaging the coherent diffraction radiation (CDR) produced by a non-invasive circular aperture. Due to the bunch lengths involved, the radiation produced is in the THz range. This has led to the development of a novel THz imaging system, which can be applied to low energy electron beams. For high energy beams the imaging system can be used as a single shot technique. Simulation results show that the profile of a CDR image of a beam is sensitive to bunch length and can thus be used as a diagnostic. The associated benefits of this imaging distribution methodology over the typical angular distribution measurement are discussed. Plans for experiments conducted at the SwissFEL (PSI, Switzerland), along with plans for future high energy single shot measurements are also presented.
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WEPAF036	Energy Independence in Optical Transition Radiation Imaging	simulation, electron, diagnostics, optics	1898
	J. Wolfenden, R.B. Fiorito, C.P. Welsch Cockcroft Institute, Warrington, Cheshire, United Kingdom R.B. Fiorito, C.P. Welsch, J. Wolfenden The University of Liverpool, Liverpool, United Kingdom
	Funding: This work was supported by the EU under Grant Agreement No. 624890 and the STFC Cockcroft Institute core Grant No. ST/G008248/1. The exploitation of optical transition radiation (OTR) in imaging-based diagnostics for charged particle beams is a well-established technique. Simulations of the expected OTR transverse beam profiles are therefore important in both the design of such imaging systems and the analysis of the data. Simulating OTR images is relatively straightforward for low energy electron beams. However, in the near future electron machines will be using high-energy and low-emittance beams. Using such parameters can be challenging to simulate, and can be limiting in their account of practical factors, e.g. chromatic aberrations. In this work we show systematically that the use of low-energy parameters in high-energy OTR image simulations induces little deviation in the resulting transverse beam profiles. Simulations therefore become much easier to perform, and further analysis may be performed. This opens up exciting opportunities to perform simulations quicker and with reduced demands on the computation requirements. It will be shown in this contribution how this approach will enable enhanced ways to optimize OTR diagnostics.
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WEPAF060	Non-Invasive Bunch Length Diagnostics for High Intensity Beams	detector, electron, real-time, simulation	1964
	S.V. Kuzikov, S.P. Antipov Euclid TechLabs, LLC, Solon, Ohio, USA S.V. Kuzikov, A.A. Vikharev IAP/RAS, Nizhny Novgorod, Russia
	Modern particle accelerators utilize photoinjectors and compression schemes to produce short high peak current electron bunches for various applications like x-ray free electron lasers, high gradient beam driven acceleration and others. Bunch length detection is a desired diagnostics for such machines. In this paper we describe a non-invasive, real-time detector which can be retrofitted into an existing beamline and measure the bunch length in real time using interferometric methods. Diffraction radiation is the mechanism to be used to produce a measurable signal without intercepting the beam. This became possible as sensitivity of pyrodetectors improved over the years, while peak beam power grew. For high peak current beams there is a possibility of a single shot measurement. This can be done with a pair of closely placed vacuum breaks that create a spatial correlation of the generated signals which can be measured by a pyro-detector array or a THz camera. The bunch length is determined from the correlation data using an iterative beam profile recovery algorithm.
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WEPAF074	Non-invasive Beam Diagnostics with Cherenkov Diffraction Radiation	photon, detector, electron, plasma	2005
	T. Lefèvre, M. Bergamaschi, O.R. Jones, R. Kieffer, S. Mazzoni CERN, Geneva, Switzerland L.Y. Bartnik, M.G. Billing, Y.B.P. Bordlemay Padilla, J.V. Conway, M.J. Forster, J.P. Shanks, S. Wang Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA M. Bergamaschi, P. Karataev Royal Holloway, University of London, Surrey, United Kingdom V.V. Bleko, A.S. Konkov, J.S. Markova, A. Potylitsyn TPU, Tomsk, Russia L. Bobb DLS, Oxfordshire, United Kingdom K. Lekomtsev JAI, Egham, Surrey, United Kingdom
	Based on recent measurements of incoherent Cherenkov Diffraction Radiation (ChDR) performed on the Cornell Electron Storage Ring, we present here a concept for the centering of charged particle beams when passing close to dielectric material. This would find applications as beam instrumentation in dielectric capillary tubes, typically used in novel accelerating technologies, as well as in collimators using bent crystals for high-energy, high-intensity hadron beams, such as the Large Hadron Collid-er or Future Circular Collider. As a charged particle beam travels at a distance of a few mm or less from the surface of a dielectric material, incoherent ChDR is produced inside the dielectric. The photons are emitted at a large and well-defined angle that allows their detection with a limited contribution of background light. A set of ChDR detectors distributed around a dielectric would enable both the beam position and tilt angle to be measured with a good resolution.
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WEPAF081	An Enhanced Quench Detection System for Main Quadrupole Magnets in the Large Hadron Collider	quadrupole, monitoring, controls, power-supply	2032
	J. Spasic, D.O. Calcoen, R. Denz, V. Froidbise, S. Georgakakis, T. Podzorny, A.P. Siemko, J. Steckert CERN, Geneva, Switzerland
	To further improve the performance and reliability of the quench detection system (QDS) for main quadrupole magnets in the Large Hadron Collider (LHC), there is a planned upgrade of the system during the long shutdown period of the LHC in 2019-2020. While improving the already existing functionalities of quench detection for quadrupole magnets and field-bus data acquisition, the enhanced QDS will incorporate new functionalities to strengthen and improve the system operation and maintenance. The new functionalities comprise quench heater supervision, interlock loop monitoring, power cycling possibility for the whole QDS and its data acquisition part, monitoring and synchronization of trigger signals, and monitoring of power supplies. In addition, the system will have two redundant power supply feeds. Given that the enhanced QDS units will replace the existing QDS units in the LHC tunnel, the units will be exposed to elevated levels of ionizing radiation. Therefore, it is necessary to design a radiation tolerant detection system. In this work, an overview of the design solution for such enhanced QDS is presented.
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WEPAF082	A Systematic Analysis of the Prompt Dose Distribution at the Large Hadron Collider	operation, luminosity, experiment, proton	2036
	O. Stein, K. Bilko, M. Brugger, S. Danzeca, D. Di Francesca, R. Garcia Alia, Y. Kadi, G. Li Vecchi, C. Martinella CERN, Geneva, Switzerland
	During the operation of the Large Hadron Collider (LHC) the continuous particle losses create a mixed particle radiation field in the LHC tunnel and the adjacent caverns. Exposed electronics and accelerator components show dose dependent accelerated aging effects. In order to achieve an optimal lifetime associated to radiation damage, the position of the equipment is chosen in dependency of the amplitude of the radiation fields. Based on the continuous analysis of the data from more than 3900 ionisation chamber beam loss monitors the evolution of the radiation levels is monitored during the accelerator operation. Normalising the radiation fields with either the integrated luminosity or the integrated intensities allows extrapolating the radiation levels of future accelerator operation. In this paper, the general radiation levels in the arcs and the insertion regions at the LHC and their evolution will be presented. The changes in the prompt dose distribution along the LHC between the operation in 2016 and 2017 will be discussed. The impact of different accelerator settings on the local dose distribution will be addressed as well.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF082
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WEPAF083	Distributed Optical Fiber Radiation Sensing at CERN	synchrotron, distributed, operation, extraction	2039
	G. Li Vecchi, M. Brugger, S. Danzeca, D. Di Francesca, R. Ferraro, Y. Kadi, O. Stein CERN, Geneva, Switzerland S. Girard Univ-Lyon Laboratoire H. Curien, UMR CNRS 5516, Saint Etienne, France
	The CERN's accelerator tunnels are associated with very complex mixed field radiation environments. Radiation degrades electronic components and directly affects their lifetimes causing failures that contribute to the machine downtime periods. In our contribution, we will report on the development and first employment of a Distributed Optical Fiber Radiation Sensor (DOFRS) at CERN. The most interesting feature of DOFRS technology is to provide an online and spatially distributed map of the dose levels in large machines with spatial resolution of the order of one meter. This fiber based dose sensor will provide valuable information in addition to the currently installed active and passive dosimeters. After demonstrating the working principle of DOFRS, the first operational prototype was installed in the Proton Synchrotron Booster during last 2016/17 end-of-the-year technical stop. The DOFRS has been acquiring data successfully since the beginning of 2017 operations. The performances that were achieved by the first prototype will be discussed in the final contribution. The DOFRS measurements will also be bench-marked to the results provided by other punctual dosimeters. I. Toccafondo et al., 'Distributed Optical Fiber Radiation Sensing in a Mixed-Field Radiation Environment at CERN,' J. Lightw. Technol. 35, 3303, 3310, 2017.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAF083
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WEPAG003	Hadron Beam Monitor Design with Gas-Filled RF Resonators in Intense Neutrino Source	cavity, hadron, scattering, target	2067
	M.D. Balcazar, K. Yonehara Fermilab, Batavia, Illinois, USA
	Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 and DOE STTR Grant, No. DE-SC0013795. For the future Long Baseline Neutrino Facility at Fermilab, a new radiation-robust hadron beam profile monitor has been proposed consisting of an interface of gas-filled radiofrequency cavity detectors in the backward region of the LBNF decay pipe. A tailored monitor layout will be used along with the new RF instrumentation. Proposed designs for the detector configuration include a variety of radially symmetric arrangements of RF resonators located at the position of maximum gradient in the beam distribution across the monitor. Until the final detector cavities are available, a prototype tunable Q-factor RF cavity will provide functional emulation for studies of the monitor layout configurations presented here.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPAG003
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WEPAL004	The Algorithm Research of DBPM for HEPS	synchrotron, synchrotron-radiation, collider, injection	2147
	F. Liu, J.S. Cao, Y.Y. Du, S.J. Wei IHEP, People's Republic of China
	The High Energy Photon Source (HEPS) is a 6-GeV, low-emittance, 1300m scale new generation photon source to be built in China [1]. As a key component, digital beam positon monitor (DBPM) needs to make the beam slow acquisition's resolution up to 0.1um. Because of the high requirements and large expenses, we designed our own DBPM system. In this paper, I will present the algorithm of our BPM. The algorithm is based on Discrete Fourier Transform (DFT) method and tested in BEPCII with using our own designed hardware. The Turn-by-Turn's resolution tested in BEPCII is 0.62um (STD value, 65080 counts, 1.2432MHz), the fast acquisition's resolution is 0.32um (STD value, 65080 counts, 10kHz), the slow acquisition's resolution is 0.18um (STD value, 65080 counts, 10Hz).
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WEPAL011	iPipe: An Innovative Fiber Optic Monitoring System for Beam Induced Heating on Accelerator Pipes	monitoring, experiment, operation, detector	2166
	F. Fienga, S. Buontempo, M.R. Masullo INFN-Napoli, Napoli, Italy A. Ball, N. Beni, B. Salvant, W. Zeuner CERN, Geneva, Switzerland G. Breglio, A. Irace University of Napoli Federico II, Napoli, Italy Z. Szillasi ATOMKI, Debrecen, Hungary V.G. Vaccaro Naples University Federico II and INFN, Napoli, Italy
	The iPipe project consists in the instrumentation, with Fiber Bragg Grating sensors (FBGs), of the beam pipe of the CMS experiment, which is part of the LHC. Being spectrally encoded, the FBGs are not sensitive to electromagnetic interference and broadband-radiation-induced losses. These characteristics allow to realize long distance punctual sensing systems, capable to operate in harsh environments like the underground experimental and accelerator facilities at CERN. The iPipe secures the measurement of any deformation induced on the central beam pipe by any motion in the CMS detector due to element displacement or to magnetic field induced deformations. Moreover, the iPipe FBG temperature sensors represent a unique solution to monitor the beam pipe thermal behavior during the various operational and maintenance phases. This paper reports the use of the iPipe to measure the beam induced heating on the CMS vacuum chamber throughout 2016 and 2017. A first comparison between the measurements and the heat load predicted from beam induced RF heating due to the coupling impedance of the CMS pipe is also reported.
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WEPAL013	Design of the Diagnostic Stations for the ELI-NP Compton Gamma Source	electron, optics, linac, simulation	2173
	M. Marongiu INFN-Roma, Roma, Italy M. Castellano, E. Chiadroni, G. Di Pirro, G. Franzini, A. Giribono, V. Shpakov, A. Stella, A. Variola INFN/LNF, Frascati (Roma), Italy A. Cianchi Università di Roma II Tor Vergata, Roma, Italy A. Mostacci, L. Palumbo Sapienza University of Rome, Rome, Italy
	A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with optical transition radiation (OTR) profile monitors. Furthermore, OTR angular distribution strongly depends on beam energy. Since OTR screens are typically placed in several positions along the Linac to monitor beam envelope, one may perform a distributed energy measurement along the machine. This will be useful, for instance, during the commissioning phase of the GBS in order to verify the correct functionality of the C-Band accelerating structures, due to the fact that there are OTR screens after each accelerating module. This paper deals with the studies of different optic configurations to achieve the field of view, resolution and accuracy in order to measure the energy of the beam. Several configurations of the optical detection line will be studied with simulation tools (e.g. Zemax).
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WEPAL015	Improvement of Motor Control System in J-PARC Linac and RCS	controls, operation, hardware, PLC	2180
	H. Takahashi, A. Miura, Y. Sawabe, M. Yoshimoto JAEA/J-PARC, Tokai-mura, Japan M. Kawase, T. Suzuki Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan
	In J-PARC, at the Linac wire scanner, the RCS collimator, and etc., a motor control system by VME is constructed as a drive system of them. Since the malfunction of operation occurred in the control system of the RCS collimator drive system in 2016, we decided to improve the motor control system. As a cause of malfunction, it is considered that aging of control equipment is one of them as J-PARC has been operated for more than 10 years. However, the defect did not occur in the reproduction test. Therefore, it can be considered that a malfunction occurred in the VME control system due to abnormality of the semiconductor element due to radiation ray. Then, in the improved motor control system, PLC with FA* specification with high reliability was adopted as the control device. Also, in case of unexpected event that a malfunction occurred in the PLC, the emergency stop mechanism was developed to stop the drive system by the signal of the limit switch, and a system incorporating it was constructed. In this paper, we show the inference of cause of the malfunction and details the improved motor control system with high safety. * Factory Automation
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WEPAL026	High Repetition Rate, Single-Shot Electro-Optical Monitoring of Longitudinal Electron Bunch Dynamics Using the Linear Array Detector KALYPSO	electron, storage-ring, laser, FEL	2216
	G. Niehues, E. Blomley, M. Brosi, E. Bründermann, M. Caselle, S. Funkner, A.-S. Müller, M.J. Nasse, L. Rota, M. Schuh, P. Schönfeldt, M. Weber KIT, Eggenstein-Leopoldshafen, Germany N. Hiller PSI, Villigen PSI, Switzerland
	Funding: This work is funded by the BMBF contract numbers: 05K13VKA and 05K16VKA. High repetition rate diagnostics are required when detecting single-shot electro-optical (EO) bunch profiles. The KIT storage ring KARA (KArlsruhe Research Accelerator) is the first storage ring in the world that has a near-field EO bunch-profile monitor in operation. By imprinting longitudinal electron bunch profiles onto chirped laser pulses, single-shot detection is feasible. However, limitations of available detection systems are challenging: The constraints are either given by the repetition rate or the duration of the consecutive acquisitions. Two strategies can overcome these limitations: Based on the photonic time-stretch method, the ps laser pulses can be stretched to the ns range using km long fibers. The readout with a high-bandwidth oscilloscope then enables a single-shot detection at high repetition rates. The other strategy is the development of dedicated ultra-fast photodetector arrays allowing direct detection of the ps pulses at MHz repetition rates. We developed KALYPSO, a linear detector array with a DAQ allowing to record high data-rates over long time scales. Here, we present recent results of studies of the longitudinal electron bunch dynamics using KALYPSO.
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WEPAL027	Filling Pattern Measurements Using Dead-Time Corrected Single Photon Counting	photon, synchrotron, storage-ring, data-analysis	2219
	B. Kehrer, E. Blomley, M. Brosi, E. Bründermann, A.-S. Müller, M. Schuh, P. Schönfeldt, J.L. Steinmann KIT, Karlsruhe, Germany
	Time-correlated single photon counting (TCSPC) is a versatile tool for various accelerator diagnostics aspects. Amongst others it allows a precise determination of the filling pattern. At the visible light diagnostics port at the Karlsruhe Research Accelerator (KARA), the KIT storage ring, a Single-Photon Avalanche Diode (SPAD) in combination with a histogramming device (PicoHarp) is used. To compensate for possible dead-time effects, a correction scheme was developed and tested successfully. The compensation increases the dynamic range in which accurate measurements are possible and avoids distortion of the measured filling pattern. This contribution presents the experimental setup, as well as a series of benchmark measurements.
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WEPAL028	Study of the Influence of the CSR Impedance on the Synchronous Phase Shift at KARA	impedance, synchrotron, simulation, storage-ring	2223
	P. Schönfeldt, E. Blomley, M. Brosi, E. Bründermann, J. Gethmann, B. Kehrer, A.-S. Müller, A.I. Papash, J.L. Steinmann KIT, Karlsruhe, Germany
	Funding: This work has been supported by the German Federal Ministry of Education and Research (Grant No. 05K16VKA) and the Helmholtz Association (Contract No. VH-NG-320). Measurements of the bunch current dependent synchronous phase shift are a standard method to characterize the impedance of a storage ring. To study this shift, different experimental approaches can be used. In this contribution, we first derive the phase shift caused by the impedance describing the emission of coherent synchrotron radiation (CSR) based on numerical simulations of the longitudinal phase space. The predicted shift is compared to measurement results obtained by time-correlated single photon counting.
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WEPAL034	Bunch Length Measurements Using Coherent Smith-Purcell Radiation With Several Gratings at CLIO	booster, detector, laser, experiment	2239
	N. Delerue, S. Jenzer, V. Khodnevych, A. Migayron LAL, Orsay, France J.P. Berthet, N. Jestin, J.-M. Ortega, R. Prazeres CLIO/ELISE/LCP, Orsay, France
	Funding: Financially supported by the Université Paris-Sud (programme "attractivité"), by the French ANR (contract ANR-12-JS05-0003-01) and by IN2P3. Coherent Smith Purcell radiation allows the measurement of a beam longitudinal profile through the study of the emission spectrum of the radiation emitted when a grating is brought close from the beam. In order to increase the dynamic range of our measurements we have used several gratings and we report on the measured bunch form factor using this technique. We report on these measurements and on the background rejection used.
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WEPAL055	TPS Beam Trip Analysis and Dose Distribution	kicker, SRF, neutron, storage-ring	2302
	B.Y. Chen, F.Y. Chang, S. Fann, C.S. Huang, C.H. Kuo, T.Y. Lee, C.C. Liang, W.Y. Lin, Y.C. Lin, Y.-C. Liu NSRRC, Hsinchu, Taiwan
	Failure analysis during TPS users operation is im-portant to improve the performance of the TPS storage ring. In this report, we discuss the particular radiation dose patterns, relevant to different beam trips, and the development of a tool to help us analyse this dose distri-bution. We will use this analysing tool to train our ability for future failure analysis to shorten the time it takes to find the problem.
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WEPAL058	Beam Loss Studies at the Taiwan Photon Source	injection, vacuum, scattering, undulator	2309
	C.H. Huang, J. Chen, Y.-S. Cheng, K.T. Hsu, K.H. Hu, D. Lee, C.Y. Wu NSRRC, Hsinchu, Taiwan
	PIN-photodiodes and RadFETs are installed in the storage ring of the Taiwan Photon Source (TPS) to study beam loss distributions and mechanisms. In the highest dose area, the radiation comes mainly from hard X-rays produced by synchrotron bending magnets. During beam cleaning and after replacing a vacuum chamber, losses due to inelastic Coulomb scattering occur mostly downstream from bending magnets while elastic scattering causes electrons to get lost mainly after an elliptically polarizing undulator which has a limited vertical aperture. During the injection period, the beam loss pattern can be changed by modifying injection conditions or lattice settings. The beam loss usually happens in the injection section and small-aperture section. The injection efficiency can be improved by minimizing the detected injection loss.
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WEPMF009	Influence of Argon-Ion Irradiation on Field Emission from Polycrystalline Cu and Large-Grain NB Surfaces	niobium, experiment, cavity, vacuum	2384
	S. Soykarci University of Wuppertal, Wuppertal, Germany D. Lützenkirchen-Hecht, V. Porshyn, P. Serbun Bergische Universität Wuppertal, Wuppertal, Germany
	Funding: This work is funded by the BMBF project 05H15PXRB1. In the present work, systematic investigations of the enhanced field emission (EFE) from polycrystalline copper and large grain niobium surfaces before and after argon-ion irradiation with an energy of 5 keV were performed with a variation of the irradiation time. Results show that the suppression of the EFE might be achievable.
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WEPMF045	Performance of the Prototype SRF Half-Wave-Resonators Tested at Cornell for the RAON Project	cavity, SRF, multipactoring, pick-up	2468
	M. Ge, F. Furuta, T. Gruber, S.W. Hartman, M. Liepe, J.T. Maniscalco, T.I. O'Connell, P.J. Pamel, J. Sears, V. Veshcherevich Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA B.H. Choi, J. Joo, J.W. Kim, W.K. Kim, J. Lee, I. Shin IBS, Daejeon, Republic of Korea
	Two prototype superconducting half-wave-resonator (162.5 MHz and β=0.12) for the RAON project have been successfully tested at Cornell University. Detailed vertical performance testing included (1) test of the bare cavity without the helium tank, and (2) test of the dressed cavity with a helium tank. In this paper, we report on the development of the test infrastructure, test results, and performance data analysis, showing that the specifications for RAON were met.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-WEPMF045
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WEPMF053	XFEL Modulators with Pulse Cables	FEL, operation, klystron, linac	2487
	H.-J. Eckoldt, S. Choroba, T. Grevsmühl, A. Hauberg, J. Havlicek, N. Heidbrook, K. Machau, N. Ngada DESY, Hamburg, Germany M. Frei, S.G. Keens, T.H. Strittmatter Ampegon AG, Turgi, Switzerland H. Leich DESY Zeuthen, Zeuthen, Germany
	The modulators of the European XFEL produce high voltage, at the 10kV level, having a power of up to 16.8 MW for 1.54 ms. The operation frequency of the super-conducting inac is 10 Hz. The series production of the 29 modulators started in 2012. The first modulator began operation in 2014 and the start of linac was beginning 2017. The R&D phase for the modulators started directly with the development of superconducting cavities. Besides the pulse generation, the modulator had to suppress the 10 Hz repetition rate in order not to disturb the grid. Another unique demand was the development of pulse cables. Since the power RF had to be generated in the tunnel, the klystrons were installed near the cavities. However, the modulators had to be installed outside of the tunnel for space, maintenance reasons and radiation concerns. This transmission of high power pulses via long cables is unique in the world and the suppression of EMI effects was mandatory. During the first year operation no EMI disturbances of other systems were detected and the modulator system works as expected.
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WEPMF057	PETRA III Vacuum System - Experiences from the First Decade of Operation	vacuum, operation, photon, experiment	2499
	L. Lilje, R. Bospflug, N. Plambeck DESY, Hamburg, Germany
	In 2008 the construction of the PETRA III vacuum system started. A year later the first photons were delivered to initial experiments and in 2010 the user operation started. In this paper the operation of the vacuum system will be reviewed. Some of the lessons learned in the initial phase will be presented as well as the main upgrades since then. By now the vacuum system has shown a very high reliability and shows no significant impact on the availability of the machine.
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WEPMF081	Mechanical Strain Measurements Based on Fiber Bragg Grating Down to Cryogenic Temperature - R&D Study and Applications	cryogenics, superconducting-magnet, GUI, experiment	2572
	M. Guinchard, A. Bertarelli, L. Bianchi, F.B. Boyer, M. Cabon, M. Calviani, O. Capatina, A. Catinaccio, P. Ferracin, P. Grosclaude CERN, Geneva, Switzerland
	In recent years, optical fiber sensors have been increasingly used due to their outstanding performances. Their application is preferable in case of special requirements that exclude the application of conventional electrical sensors. The scientific background of optical fiber sensors is well developed. However, the characteristic of sensors employed in rather harsh environments is often different from the one determined in laboratory conditions or prior to their installation. In order to achieve long-term stable functioning and reliable measurement under severe working environments, such as those occurring at CERN (radiation, cryogenics, high magnetic and electrical field), a statistical measurement campaign was carried out following the international standard ISO 5725. The paper describes the ongoing study to define the accuracy of optical fiber sensors based on Fiber Bragg Grating (FBG) for strain measurements, from room temperature down to 4.2 K. It also describes some of the demanding applications for which optical fiber sensors have been deployed to perform experimental strain measurements (e.g. detectors components, high-energy beam targets and dumps, superconducting magnets).
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WEPMF084	Design, Prototyping Activities and Beam Irradiation Test for the New n_TOF Neutron Spallation Target	target, interface, neutron, proton	2582
	R. Esposito, M. Bergeret, J. Busom, M.E.J. Butcher, M. Calviani, R. Cimmino, T. Coiffet, J.P.C. Espadanal, L. Gentini, R. Illan Fiastre, V. Maire, F. Ogallar Ruiz, A. Perillo-Marcone, S. Sgobba, M.A. Timmins, C. Torregrosa, E. Urrutia, V. Vlachoudis CERN, Geneva, Switzerland R. Logé EPFL, Lausanne, Switzerland
	A third-generation neutron spallation target for the neutron time-of-flight facility at CERN (n_TOF) is currently undergoing the design and prototyping stage. The new design aims at improving reliability, increasing beam intensity on target and avoiding issues encountered in the current generation target, in particular the contamination of the cooling system water with radioactive spallation products coming from washing out lead. After a preliminary design and an initial prototyping stage, a baseline solution has been defined consisting in a pure lead target core contained in a Ti-6Al-4V cladding and embedded in a massive Pb block. A backup solution has also been defined, consisting in a Ta-cladded W core embedded in a Pb block. Both solutions are currently undergoing the detailed design stage. This contribution details the prototyping activity, the robustness studies for accidental scenarios and the design of a beam irradiation test on prototypes of the target core. R. Esposito et al., "Design of the new CERN n_TOF neutron spallation target: R&D and prototyping activities," in Proc. of IPAC'17, Copenhagen, May 2017.*
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WEPMG002	Beam Dump Facility Target: Design Status and Beam Tests in 2018	target, operation, experiment, simulation	2604
	E. Lopez Sola, O. Aberle, P. Avigni, L. Bianchi, J. Busom, M. Calviani, M. Casolino, J.P.C. Espadanal, M.A. Fraser, S. Girod, B. Goddard, D. Grenier, M. Guinchard, C. Heßler, R. Illan Fiastre, R. Jacobsson, M. Lamont, A. Ortega Rolo, B. Riffaud, G. Romagnoli, L. Zuccalli CERN, Geneva, Switzerland
	The Beam Dump Facility (BDF) Project, currently in its design phase, is a proposed general-purpose fixed target facility at CERN, dedicated to the Search for Hidden Particles (SHiP) experiment in its initial phase. At the core of the installation resides the target/dump assembly, whose aim is to fully absorb the high intensity 400 GeV/c SPS beam and produce charmed mesons. In addition to high thermo-mechanical loads, the most challenging aspects of the proposed installation lie in very high energy and power density deposition that are reached during operation. In order to validate the design of the BDF target, a scaled prototype is going to be tested during 2018 in the North Area at CERN, upstream the existing beryllium primary targets. The prototype testing under representative beam scenarios will allow having an insight of the material response in an unprecedented regime. Online monitoring and an extensive Post Irradiation Experimental (PIE) campaign are foreseen. The current contribution will detail the design and handling aspects of the innovative Target Complex as well as the design of the BDF target/dump core and the design and construction of the prototype target assembly.
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WEPMG006	Experimental Setup to Characterize the Radiation Hardness of Cryogenic Bypass Diodes for the HL-LHC Inner Triplet Circuits	cryogenics, MMI, quadrupole, target	2620
	A. Will, G. D'Angelo, R. Denz, M.F. Favre, D. Hagedorn, G. Kirby, T. Koettig, A. Monteuuis, F. Rodriguez-Mateos, A.P. Siemko, K. Stachon, M. Valette, A.P. Verweij, D. Wollmann CERN, Geneva, Switzerland A. Bernhard, A.-S. Müller KIT, Karlsruhe, Germany L. Kistrup KEA, Copenhagen, Denmark
	Funding: Work supported by the Wolfgang Gentner Programme of the German Federal Ministry of Education and Research For the high luminosity upgrade of the Large Hadron Collider (LHC), it is planned to replace the existing triplet quadrupole magnets with Nb₃Sn quadrupole magnets, which provide a comparable integrated field gradient with a significantly increased aperture. These magnets will be powered through a novel superconducting link based on MgB₂ cables. One option for the powering layout of this triplet circuit is the use of cryogenic bypass diodes, where the diodes are located inside an extension to the magnet cryostat and operated in superfluid helium. Hence, they are exposed to radiation. For this reason the radiation hardness of existing LHC type bypass diodes and more radiation tolerant prototype diodes needs to be tested up to the radiation doses expected at their planned position during their lifetime. A first irradiation test is planned in CERN's CHARM facility starting in spring 2018. Therefore, a cryo-cooler based cryostat to irradiate and test LHC type diodes in-situ has been designed and constructed. This paper will describe the properties of the sample diodes, the experimental roadmap and the setup installed in CHARM. Finally, the first measurement results will be discussed.
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WEPML023	Design and Test Results of the 3.9 GHz Cavity for LCLS-II	cavity, cryomodule, operation, FEL	2730
	N. Solyak, S. Aderhold, S.K. Chandrasekaran, C.J. Grimm, T.N. Khabiboulline, A. Lunin, O.V. Prokofiev, G. Wu Fermilab, Batavia, Illinois, USA
	The LCLS-II project uses sixteen 3.9 GHz superconduct-ing cavities to linearize energy distribution before the bunch compressor. To meet LCLS-II requirements origi-nal FNAL design used in FLASH and XFEL was signifi-cantly modified to improve performance and provide reliable operation up to 16 MV/m in cw regime [1-3]. Four prototype cavities were built and tested at vertical cryo-stat. After dressing, one cavity was assembled and tested at horizontal cryostat as part of design verification pro-gram. All auxiliaries (magnetic shielding, power and HOM couplers, tuner) were also re-designed and tested with this cavity. In this paper we will discuss cavity and coupler design and test results.
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WEPML055	Simulation Study of Parasitic-Mode Damping Methods for a 1.5-GHz TM020-Mode Harmonic Cavity	cavity, impedance, damping, coupling	2822
	N. Yamamoto, S. Sakanaka, T. Takahashi KEK, Ibaraki, Japan
	Design study of parasitic-mode (PM) damped structures has been conducted for the purpose to realize a normal conducting 1.5 GHz harmonic cavity which is based on the TM020 resonant mode. We have investigated the performances of two PM-damping mechanisms, that are, rod-type antennas* and annular slots. The rod-type antennas locate at the node of electric field of the TM020 mode while the annular slots locate at the node of magnetic field. As a result of 3D electromagnetic simulations, suitable performances of PMs were confirmed by employing either of the PM-damping mechanisms. It was also shown that the slot-type structure is superior in PM-damping performance and in the unloaded Q of the TM020 mode. * N. Yamamoto et al., IPAC'17, paper THOPIK037; N. Yamamoto Phys. Rev. Accel. Beams, 21, 1, 012001. ** T. Takahashi et al., IPAC'17, paper THPIK036.
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THXGBE2	Optical Diagnostics for Extreme Beam Conditions	emittance, diagnostics, electron, experiment	2896
	R.B. Fiorito The University of Liverpool, Liverpool, United Kingdom
	The development of simple, fast, precise and robust beam diagnostics is absolutely necessary to optimize the performance of present accelerators and to satisfy the needs of future accelerators, in particular those with ex-treme properties such as high brightness FELs and plasma wake-field accelerators. This invited talk will present the underlying physics and results from simulation and experiments for a number of advanced optical beam diagnostics currently under development at various accelerator re-search laboratories including efforts at the Cockcroft Institute.
	Slides THXGBE2 [13.917 MB]
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THPAF012	The Influence of Chromaticity on Transverse Single-Bunch Instability in the Booster of HEPS	simulation, booster, damping, injection	2968
	H.S. Xu, N. Wang IHEP, Beijing, People's Republic of China
	The study of the transverse single-bunch instability has been carried out for the HEPS booster to double check whether the required single-bunch charge can be achieved. The chromaticity has been varied in our study to see how the threshold changes accordingly. Usually, the slightly positive chromaticity is expected for stabilizing the beam. However, our simulations show that the single-bunch threshold current drops significantly when the chromaticity becomes non-zero. We present the simulation methods and results in details in this paper. The analysis of the simulation results is also presented.
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THPAK010	Optimization on the Optical Resonator of CTFEL	FEL, GUI, coupling, electron	3228
	X.J. Shu, Y.H. Dou Institute of Applied Physics and Computational Mathematics, People's Republic of China M. Li, Z. Xu, Y. Xu, X. Yang CAEP/IAE, Mianyang, Sichuan, People's Republic of China
	Funding: Program for the National Science Foundation of China (Grant No. 11105019) and the National Science Device Exploitation Foundation of China (Grant No. 2011YQ130018). A high power THz free electron laser (FEL) facility is under construction at China Academy of Engineering Physics (CTFEL) since October, 2011. The radiation frequency of the FEL facility will be tuned in range of 1~3 THz and the average output power is about 10 W. The system mainly consists of a GaAs photoemission DC gun, superconductor accelerator, the hybrid wiggler, optical cavity. The first lasing is obtained on Aug. 29, 2017. The optical resonator of CTFEL is optimized to ensure wavelength tunable in a wide range and high power operation. The FEL power strongly depends on the performance of the optical resonator including output efficiency, gain and round-trip loss. The optical resonator consists of metal-coated reflect mirror, the center-hole output mirror, waveguide. The influence of waveguide and Rayleigh length on the quality of optical cavity is evaluated by the 3D-OSIFEL code. The waveguide size, mirror curvature radius, output hole radius is optimized to different frequencies between 1 THz to 3 THz.
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THPAK025	Recent Developments in Beam Delivery Simulation - BDSIM	simulation, dipole, sextupole, interface	3266
	L.J. Nevay, A. Abramov, S.T. Boogert, H. Garcia Morales, S.M. Gibson, W. Shields, S.D. Walker JAI, Egham, Surrey, United Kingdom J. Snuverink PSI, Villigen PSI, Switzerland
	Funding: Work supported by Science and Technology Research council grant 'The John Adams Institute for Accelerator Science' ST/P00203X/1 and Impact Acceleration Account. Beam Delivery Simulation (BDSIM) is a program to seamlessly simulate the passage of particles in an accelerator, the surrounding environment and detectors. It uses a suite of high energy physics software including Geant4, CLHEP and ROOT to create a 3D model from an optical description of an accelerator and simulate the interaction of particles with matter as well as the production of secondaries. BDSIM is used to simulate energy deposition and charged particle backgrounds in a variety of accelerators worldwide. The latest developments are presented including low-energy tracking extension, more detailed geometry, support for ion beams and improved magnetic fields. A new analysis suite that allows scalable event by event analysis is described for advanced analysis such as the trace back of energy deposition to primary particle impacts.
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THPAK029	Studies of the Micro-Bunching Instability in the Presence of a Damping Wiggler	damping, wiggler, synchrotron, bunching	3273
	M. Brosi, A. Bernhard, J. Gethmann, B. Kehrer, A.-S. Müller, A.I. Papash, P. Schreiber, P. Schönfeldt, J.L. Steinmann KIT, Karlsruhe, Germany
	Funding: Funded by BMBF (grant: 05K16VKA) & Helmholtz (contract: VH-NG-320). Supported by the Helmholtz International Research School for Teratronics & Karlsruhe School of Elementary and Astroparticle Physics. At the KIT storage ring KARA (KArlsruhe Research Accelerator), the momentum compaction factor can be reduced leading to natural bunch lengths in the ps range. Due to the high degree of longitudinal compression the micro-bunching instability arises. During this longitudinal instability the bunches emit bursts of intense coherent synchrotron radiation in the THz frequency range caused by the complex longitudinal dynamics. The temporal pattern of the emitted bursts depends on given machine parameters, like momentum compaction factor, acceleration voltage, and damping time. In this paper the influence of the damping time is studied by utilizing the CLIC damping wiggler prototype installed in KARA as well as by simulations using the Vlasov-Fokker-Planck solver Inovesa.
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THPAK044	Self-Consistent Modeling using a Lienard-Wiechert Particle-Mesh Method	space-charge, simulation, synchrotron, emittance	3313
	R.D. Ryne, C.E. Mitchell, J. Qiang LBNL, Berkeley, California, USA B.E. Carlsten LANL, Los Alamos, New Mexico, USA
	In this paper we describe a parallel, large-scale simulation capability using a Lienard-Wiechert Particle-Mesh (LWPM) method. The approach is a natural extension of the convolution-based technique to solve the Poisson equation in space-charge codes. It provides a unified method to compute both Coulomb-like self-fields and radiative phenomena like coherent synchrotron radiation (CSR). The approach brings together several mathematical and computational capabilities including the use of integrated Green function (IGF) methods and adaptive quadrature methods. We will describe the theoretical model and our progress to date.
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THPAK051	Computer Simulation of Explosive Emission Electrons Acceleration and X-ray Quantum Generation in Pulse Coaxial Diode System with Interior Anode	cathode, electron, simulation, target	3333
	V.I. Rashchikov, A.A. Isaev, A.E. Shikanov, E.A. Shikanov MEPhI, Moscow, Russia
	Computer simulation of electrons from explosive emission acceleration and X-ray quantum generation in pulse coaxial diode system with interior anode, which is used in accelerating tube of compact X-ray generator* with Tesla transformer as high voltage source, was done. The results obtained allow us to choose accelerating tube diode system geometry for different running modes. Comparison of numerical results with experimental data of dose rate dependence on the distance from vacuum tube anode and energy at first circuit Tesla transformer was fulfilled. *Patent RF N71817, 03.10.2007
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THPAK053	Side Effects of Local Bump in TPS Storage Ring	sextupole, quadrupole, storage-ring, dipole	3340
	M.-S. Chiu, C.H. Chen, J.Y. Chen, P.J. Chou, F.H. Tseng NSRRC, Hsinchu, Taiwan
	The Taiwan Photon Source (TPS) is a low-emittance 3-GeV light source at National Synchrotron Radiation Research Center. Five in-vacuum undulator beamlines were delivered to users on Sep. 22, 2016. Another 2 EPU beamlines will be open to user in near future. In the beginning, the local bump was used to do ID spectrum optimization since 2016. After this procedure, the ID spectrum are consistent between theoretical simulation and measurement. Recently, we found the local bump will cause tune shift and orbit distortion. In this paper, we will present the effect of local bump in TPS.
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THPAK057	Simulations of Optical Stochastic Cooling with ELEGANT	damping, undulator, pick-up, kicker	3354
	M.B. Andorf, P. Piot Northern Illinois University, DeKalb, Illinois, USA V.A. Lebedev, V.A. Lebedev, P. Piot Fermilab, Batavia, Illinois, USA
	Fermilab is pursuing a proof-of-principle test of the Optical Stochastic Cooling (OSC) of 100 MeV electrons in the Integrable Optics Test Accelerator. In support of this we present simulations of horizontal damping with OSC. We find excellent agreement with theory on the amplitude dependent damping rates. Additionally particle tracking is used to confirm the necessity and effectiveness of sextupoles used to correct non-linear path lengthening in the OSC chicane.

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MOZGBD3

Performance of the First LCLS-II Cryomodules: Issues and Solutions

cavity, cryomodule, HOM, operation

34

N. Solyak, E. Cullerton, J. Einstein-Curtis, E.R. Harms, B.D. Hartsell, J.P. Holzbauer, T.N. Khabiboulline, A. Lunin, Y.M. Pischalnikov, R.P. Stanek, G. Wu
Fermilab, Batavia, Illinois, USA
O. Napoly
CEA/DSM/IRFU, France

LCLS-II 4 GeV linac is on the middle production stage. Linac contains 40 cryomodules of 1.3 GHz and 3 cryomodules of 3.9 GHz, including spares. Fermilab and JLAB share responsibility for cryomodule design, assembly and test. Paper will overview the performance of the cryomodules it the tests, lessons learned and modifications in design to improve performance.

Slides MOZGBD3 [8.630 MB]

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MOZGBD5

A Proposal for Coherent Hard X-Ray Generation Based on Two-Stage EEHG

FEL, electron, laser, linac

38

Z.T. Zhao, J.H. Chen, C. Feng, Z. Wang, K.Q. Zhang
SINAP, Shanghai, People's Republic of China

A two stage echo-enabled harmonic generation (EEHG) scheme to produce coherent hard X-rays is presented. Electron bunchs of quite different lengths are separately used in each stage of EEHG and a monochromator is employed to purify the radiation from the first stage for seeding the second one. Theoretical analysis and 3D simulations show that the proposed scheme can generate fully coherent hard X-ray pulses directly from a conventional UV seed laser.

Slides MOZGBD5 [7.330 MB]

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MOZGBE5

Results on the FCC-hh Beam Screen at the KIT Electron Storage Ring KARA

photon, electron, experiment, vacuum

55

L.A. Gonzalez, V. Baglin, P. Chiggiato, C. Garion, M. Gil Costa, 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 3 FCC-hh beam-screen (BS) prototypes has been carried out with the aim of testing them at room temperature at the Karlsruhe Institute of Technology (KIT) 2.5 GeV electron storage ring KARA (KArlsruhe Research Accelerator). The 3 BS prototypes will be 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 the one foreseen for the 50+50 TeV FCC-hh proton collider. Each of the 3 BS prototypes, 2 m in length, implement a different design feature: 1) baseline design (BD), with electro-deposited copper and no electron-cloud (EC) mitigation features; 2) BD with set of distributed cold-sprayed anti-EC clearing electrodes; 3) BD with laser-ablated anti-EC surface texturing. We present here the results obtained so far at BESTEX and the comparison with extensive montecarlo simulations of the expected outgassing behavior under synchrotron radiation.
The information herein only reflects the views of its authors and the European Commission is not responsible for any use that may be made of the information.

Slides MOZGBE5 [4.318 MB]

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MOPMF036

FCC-ee Hybrid RF Scheme

cavity, HOM, impedance, operation

173

Sh. Gorgi Zadeh, U. van Rienen
Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
R. Calaga, F. Gerigk
CERN, Geneva, Switzerland

Funding: Research supported by the FCC design study
For FCC-ee, the range of beam energies and beam currents is large between each mode of operation, all scaled to an available 50 MW maximum power per beam. The two limiting scenarios for the RF system design are at low energy (45 GeV) with high beam current (1.45 A) and the highest energy (182.5 GeV) with a radiation loss reaching 8.92 GeV per turn. In this paper, RF staging with a hybrid scheme using both 400 MHz and 800 MHz is proposed to mitigate the requirements on the two extremes. Relevant comparisons are made with respect to using only a single frequency for all modes.

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MOPMF068

Quantum Excitation due to Classical Beamstrahlung in Circular Colliders

collider, photon, simulation, emittance

281

M.A. Valdivia García, D. El Khechen, K. Oide, F. Zimmermann
CERN, Geneva, Switzerland

In the collisions of proposed future circular colliders, like FCC-ee and CEPC, the beamstrahlung regime is classical, i.e. with an "Upsilon parameter" much smaller than 1. In the classical regime, for a constant electromagnetic field a simple relation exists between the average photon energy u and the average squared photon energy u², which is the same as for standard synchrotron radiation in storage rings. This relation breaks down, however, if the electromagnetic field is not constant in time and position, as is the case for a beam-beam collision. We derive an analytical expression for u²/u², considering the case of Gaussian-bunch collisions with crossing angle (and possibly crab waist). We compare our result with the photon energies obtained in beam-beam simulation for FCC-ee at beam energies of 45.6 GeV and 175 GeV, using the two independent codes BBWS and Guineapig. Finally, we re-optimize the FCC-ee parameters of a possible mono-chromatization scheme for direct Higgs production at 125 GeV, derived previously, by applying the refined expression for the rms photon energy.

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MOPMK003

Energy Deposition Studies and Luminosity Evolution for the Alternative FCC-hh Triplet

optics, luminosity, quadrupole, dipole

352

J.L. Abelleira, E. Cruz Alaniz, A. Seryi, L. van Riesen-Haupt
JAI, Oxford, United Kingdom
J.L. Abelleira, E. Cruz Alaniz, L. van Riesen-Haupt
University of Oxford, Oxford, United Kingdom

Funding: Work supported by EuroCircol, EU's Horizon 2020 grant No 654305 & STFC grant to the John Adams Institute
The international Future Circular Collider (FCC) study comprises the development of a new scientific structure in a tunnel of 100 km. This will allow the installation of a proton collider with a centre of mass energy of 100 TeV, called FCC-hh. An alternative design of the final focus triplet for the FCC-hh has been developed in parallel to the alternative one, and adapted to the constraint of a free length (L*) of 40 m. We discuss in this paper the energy deposition issues as well as the luminosity evolution for two different optics choices: round and flat beams.

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MOPML011

Liquid Cluster Ion Beam Processing of Transition Metal Films

vacuum, acceleration, target, experiment

415

D. Shimizu, H. Ryuto, M. Takeuchi, D. Yamamoto
Kyoto University, Photonics and Electronics Science and Engineering Center, Kyoto, Japan

The irradiation effects of cluster ion beams are characterized by the high-density collision of molecules that comprise the clusters against a target. According to molecular dynamics calculations, the local temperature of the colliding cluster and the surface of the target are expected to increase to several thousand K. The enhancement of the chemical interactions between the molecules in the colliding clusters and the atoms on the target surface is expected, if polyatomic molecules, such as ethanol and acetone, are used for the source material of the cluster. So, the irradiation effects of the polyatomic liquid cluster ion beams on transition metal films have been studied to examine the possibility of utilizing the liquid cluster ion beam technique for the processing of transition metal films. The transition metal films were formed by magnetron sputtering. The liquid clusters were produced by the adiabatic expansion method and ionized by electron ionization. The sputtering yields of transition metal films induced by liquid cluster ions are discussed.

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MOPML021

Shorter Treatment Time by Intensity Modulation with a Betatron Core Extraction

betatron, extraction, proton, synchrotron

439

M. G. Pullia, E. Bressi, G.M.A. Calvi, M. Donetti, L. Falbo, S. Foglio, V. Lante, A. Parravicini, C. Priano, E. Rojatti, S. Savazzi, C. Viviani
CNAO Foundation, Pavia, Italy

The CNAO (National Center for Oncological Hadrontherapy) main accelerator is a synchrotron capable to accelerate carbon ions up to 400 MeV/u and protons up to 250 MeV. Three treatment rooms are available and are equipped with horizontal beam lines; one of the treatment rooms also features a vertical treatment line to allow additional treatment ports. All of the beamlines are equipped with an active beam scanning system for dose delivery. With such a dose distribution technique, particles are sent to different depths by changing the energy from the synchrotron and are moved transversally by means of two scanning magnets. The number of particles to be deposited in each position varies strongly within the same iso-energetic layer. Part of the dose needed in a given position is in fact delivered by particles directed to deeper layers. In order to maintain the required precision on the number of particles delivered to each spot, the intensity is reduced when spots that require low number of particles are present in a layer. A method to shorten the irradiation time based on variable intensity within the same layer is presented that works also with a betatron based extraction scheme.

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MOPML022

Development of Travelling Wave Accelerating Structure for a 10 MeV E-Linac

electron, bunching, linac, simulation

443

J.H. Yang, Y. Yang
CIAE, Beijing, People's Republic of China
G. Han
China Institute of Atomic Energy, Beijing, People's Republic of China

Electron irradiation processing is a vital application field of nuclear technology application. China Institute of Atomic Energy (CIAE) developed several 10 MeV high power electron irradiating accelerator successfully, promoting the development of high energy high power irradiating accelerator technology and electron irradiation processing in China. The paper introduced the development of a 10 MeV travelling wave accelerating tube. The tube operates at 2856 MHz in 2π/3 mode. The SUPERFISH and PARMELA are used for the physical design. Several methods are used for microwave parameter measurement and tuning. The high power test shows the beam energy is 10.3 MeV and average beam power is 24.3 kW.

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MOPML028

Accelerator Machines and Experimental Activities in the ENEA Frascati Particle Accelerators and Medical Application Laboratory

experiment, proton, electron, linac

460

M. Vadrucci, A. Ampollini, G. Bazzano, F. Borgognoni, P. Nenzi, L. Picardi, C. Ronsivalle, V. Surrenti, E. Trinca
ENEA C.R. Frascati, Frascati (Roma), Italy

Funding: Regione Lazio - TOP IMPLART Project
In the ENEA Frascati research center the APAM (Particle Accelerators and Medical Application) laboratory is devoted to the development of particle accelerators for medical applications. Two main facilities are operational. The TOP-IMPLART proton accelerator is a pulsed fully linear machine aimed at active intensity modulated proton therapy with a final energy of 150 MeV. The machine offers two beam extraction points: one at 3-7 MeV, on a vertical line, and the other one at 35 MeV, the maximum energy currently available, with a pulse current up to 35 μA, on the horizontal line. The REX (Removable target Electron X-ray) source consists of an electron standing wave LINAC generating a beam in the energy range of 3 to 5 MeV with a pulsed current of 0.2 A. This source can generate Bremsstrahlung X-ray beams using suitable converters (Pb, W, Ta). This paper describes the experimental results of satellite activities performed in these facilities in the fields of biology, dosimetry, electronics, PIXE spectroscopy and preservation of cultural heritage manufacts.

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MOPML039

Comparison of Two Types of Steerers Applied in Proton Therapy Gantry

quadrupole, proton, simulation, superconductivity

488

Z.F. Zhao, Q.S. Chen, S. Hu, X. Liu, B. Qin, W. Wei
HUST, Wuhan, People's Republic of China
W. Chen
Huazhong University of Science and Technology, State Key Laboratory of Advanced Electromagnetic Engineering and Technology,, Hubei, People's Republic of China

A proton therapy project HUST-PTF (HUST Proton Therapy Facility) based on a 250MeV isochronous superconducting cyclotron is under development in Huazhong University of Science and Technology (HUST). Based on the optics design of the gantry, the steering magnets need to be placed in a compact structure, as well as meet the magnetic field requirement with a maximum deflection angle of ±5mrad@250MeV. In the paper, two types of steerers (O-shape and H-shape) were introduced and discussed in detail. The magnetic fringe field interference effects between quadrupoles and steerers were studied by using OPERA/TOSCA code. The result based on the contrastive analysis will give us a valuable reference to choose suitable steerers for proton therapy beamline.

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MOPML043

High Gradient Performance of an S-Band Backward Traveling Wave Accelerating Structure for Medical Hadron Therapy Accelerators

linac, proton, cavity, accelerating-gradient

491

A. Vnuchenko, C. Blanch Gutiérrez, D. Esperante Pereira
IFIC, Valencia, Spain
S. Benedetti, N. Catalán Lasheras, A. Grudiev, B. Koubek, G. McMonagle, I. Syratchev, B.J. Woolley, W. Wuensch
CERN, Geneva, Switzerland
A. Faus-Golfe
LAL, Orsay, France
T.G. Lucas, M. Volpi
The University of Melbourne, Melbourne, Victoria, Australia
S. Pitman
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom

The high-gradient performance of an accelerating structure prototype for a medical proton linac is presented. The structure was designed and built using technology developed by the CLIC collaboration and the target application is the TULIP (Turning Linac for Proton therapy) proposal developed by the TERA foundation. The special feature of this design is to produce gradient of more than 50 MV /m in low-β accelerating structures (v/c=0.38). The structure was tested in an S-band test stand at CERN. During the tests, the structure reached over above 60 MV/m at 1.2 μs pulse length and breakdown rate of about 5x10^-6 bpp. The results presented include ultimate performance, long term behaviour and measurements that can guide future optimization.

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MOPML045

Measurement of Displacement Cross-Section for Structural Materials in High-Power Proton Accelerator Facility

experiment, proton, target, cryogenics

499

S.I. Meigo, S.H. Hasegawa, H.I. Hiroki, H. Hiroki, Y. Iwamoto, F.M. Maekawa
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
T. Ishida, S. Makimura, T. Nakamoto
KEK, Ibaraki, Japan
Y. Makoto
J-PARC, KEK & JAEA, Ibaraki-ken, Japan

As the increase of beam power of hadron accelerators, the damage to target material is essential. For estimation of damage such as target material used at the facility, displacement per atom (DPA), calculated by the particle flux multiplied displacement cross-section with cascade mode, is widely employed as an index of the damage. Although the DPA is employed as the standard, the experimental data of displacement cross-section are scarce for a proton in the energy region above 20 MeV. A recent study reports that the displacement cross section of tungsten has 8 times difference among the calculation models. Therefore, experimental data of the displacement cross-section is crucial. The displacement cross-section can be obtained by observing the change of resistivity of the sample cooled by GM cooler to sustain the damage. The sample is placed in the vacuum chamber placed at upstream of the beam dump for 3 GeV and 30 GeV synchrotrons in J-PARC, where the sample will be irradiated by the proton in the energy range between 0.4 and 30 GeV. In the vast energy range, the displacement cross-section can be obtained for the proton, which will help to improve the damage estimation of the target material.

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MOPML048

Design Study of PM Dipole for ILC Damping Ring

dipole, permanent-magnet, damping, operation

505

Y. Iwashita
Kyoto ICR, Uji, Kyoto, Japan
N. Terunuma
KEK, Ibaraki, Japan

Dipole magnet using permanent magnet technology is under investigation for ILC cost reduction. It can reduce cost of electricity of coil excitation and cooling water pump, thick electric cabling and water piping, power supply, and their maintenance cost. The structure and the field adjustment scheme will be discussed.

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MOPML050

A Massive Open Online Course on Particle Accelerators

target, survey, neutron, synchrotron

512

N. Delerue, A. Faus-Golfe
LAL, Orsay, France
M.E. Biagini
INFN/LNF, Frascati (Roma), Italy
E. Bründermann, A.-S. Müller
KIT, Eggenstein-Leopoldshafen, Germany
P. Burrows
JAI, Oxford, United Kingdom
G. Burt
Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
C. Darve, R.A. Yogi
ESS, Lund, Sweden
V.V. Dmitriyeva, S.M. Polozov
MEPhI, Moscow, Russia
J. Kvissberg
Lund University, Lund, Sweden
P. Lebrun
JUAS, Archamps, France
E. Métral, H. Schmickler, J. Toes
CERN, Geneva, Switzerland
S.P. Møller
ISA, Aarhus, Denmark
L. Rinolfi
ESI, Archamps, France
A. Simonsson
Stockholm University, Stockholm, Sweden
V.G. Vaccaro
Naples University Federico II and INFN, Napoli, Italy

Funding: European Union H2020 - ARIES Project
The TIARA (Test Infrastructure and Accelerator Research Area) project funded by the European Union 7th framework programme made a survey of provision of education and training in accelerator science in Europe highlighted the need for more training opportunities targeting undergraduate-level students. This need is now being addressed by the European Union H2020 project ARIES (Accelerator Research and Innovation for European Science and Society) via the preparation of a Massive Online Open Course (MOOC) on particle accelerator science and engineering. We present here the current status of this project, the main elements of the syllabus, how it will be delivered, and the schedule for providing the course.

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MOPML051

First Performance Calculations for the Very High Energy Electron Radiation Therapy Experiment at PRAE

electron, experiment, proton, photon

516

A. Faus-Golfe
LAL, Orsay, France
R. Delorme, Y. Prezado
IMNC, Orsay, France
V. Favaudon, C. Fouillade, S. Heinrich, A. Mazal, A. Patriarca, P. Poortmans, P. Verrelle
Institut Curie - Centre de Protonthérapie d'Orsay, Orsay, France
A. Hrybok
National Taras Shevchenko University of Kyiv, Radiophysical Faculty, Kiev, Ukraine

The Platform for Research and Applications with Electrons (PRAE) project aims at creating a multidisciplinary R&D platform at the Orsay campus, joining various scientific communities involved in radiobiology, subatomic physics, instrumentation, particle accelerators and clinical research around a high-performance electron accelerator with beam energies up to 70 MeV and later 140 MeV, in order to perform a series of unique measurements and challenging R&D. In this paper we will report the first optics design and performance evaluations of such a multidisciplinary machine, focusing on Very High Energy Electrons (VHEE) innovative Radiation Therapy (RT) applications in particular by allowing Grid and FLASH methodologies, which are likely to represent a major breakthrough in RT. Functional specifications include beam intensities to produce dose rates from 2 Gy/min to 100Gy/sec, beam sizes with diameters from 0.5 mm to 10 cm or more of homogeneous beams and monitoring devices with accuracy in the order of 1-2% for single or multiple beams and single or multiple fractions in biological and ppreclinical applications. High energies (>140 MeV) would be also needed for GRID therapy.

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MOPML058

Comparison of Water Absorbed Dose for Photons of Linac and Traceability System for Radiotherapy in China

photon, controls, linac, electron

537

K. Wang, S. Jin, Z. Wang, J. Zhang
National Institute of Metrology, Beijing, People's Republic of China

National Institute of Metrology (NIM) developed the standards of the absorbed dose to water for high-energy photon and electron beams, to support the PSDL and SSDL calibration capability in China. After the measurement of absorbed dose to water for 6, 10, and 25 MV photons of linac, NIM took part the BIPM. RI(I).K6 comparison with the Bureau International des Poids et Mesures (BIPM). The tissue phantom ratio (TPR_20,10) of 6MV and 10MV photons were measured by IBA CC13 chamber and Keithley 6517B with different output dose of the Linac, and also calculated by the dose ratio (D₂0⁄D₁0) with the formula in IAEA TRS-398 report. TPR_20,10 measured directly is 0.3% larger than calculated by the dose ratio D₂0⁄D₁0 . The absorbed dose to water is measured by water calorimeter with the combined standard uncertainty of 0.35%. The discrepancy of absorbed dose to water measured separately by open and sealed vessel is 0.2% at 10MV. The K6 comparison was done, the results reported as ratios of the NIM and the BIPM evaluations (and with the combined standard uncertainties given in parentheses), are 0.9917(60) at 6 MV, and 0.9941(59) at 10 MV. The quality correction factor KQ of usual used chamber was measure directly, and it is 0.3%~0.7% smaller than the data in the IAEA TRS-398 report. The typical chamber-to-chamber variations of the dose obtained with the IAEA TRS-277, TRS-398 and AAPM TG-51 were between 0.2% and 1.0% for the different photon beams. The variations of the dose obtained with IAEA TRS-398 and chambers calibrated directly by megavoltage photons were between 0.1% to 0.8%. The new standard can achieve the traceability of water absorbed dose for MV photons and will significantly reduce the uncertainty of ion chamber calibrations for Chinese radiotherapy centers.

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MOPML059

Precise Beam Delivery for Proton Therapy with Dynamic Energy Modulation

proton, target, MMI, controls

540

O. Actis, A. Mayor, D. Meer, D.C. Weber
PSI, Villigen PSI, Switzerland
D.C. Weber
University of Zurich, University Hospital, Zurich, Switzerland

Gantry 2 at PSI is a Pencil Beam Scanning (PBS) cyclotron based proton therapy system. PBS proved to be an effective treatment method for static tumors but for mobile targets (e.g lung) organ motion interferes with beam delivery lowering the treatment quality. A method to mitigate motion effects is to re-scan the treatment volume multiple times. The downside of re-scanning is the increase of treatment time due to high number of energy switches and magnet initializations (ramping) between scans. Our current re-scanning implementation is performed with a decreasing energy sequence and takes about 6s/scan thanks to fast energy switching of 100ms. Ramping adds 8s more leading to a treatment time of >60s. We developed beam line settings for reverse energy sequence and removed the full ramping between scans. This dynamic beam delivery leads to non-negligible beam position errors of >1.5mm which we compensate by field specific corrections. Using a patient file we proved that our novel re-scanning concept doubles the treatment efficiency. Using in-house developed measurement equipment we obtained a precision of <0.5mm in position and <1mm in range which fulfills all clinical requirements.

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MOPML063

In Situ Observations of Blistering of a Metal Irradiated with 2 MeV Protons

proton, neutron, target, experiment

553

S.Yu. Taskaev, D.A. Kasatov, A.N. Makarov, I.M. Shchudlo
BINP SB RAS, Novosibirsk, Russia
A. Badrutdinov, Y. Higashi, T. Miyazawa
OIST, Onna-son, Okinawa, Japan
T.A. Bykov
Budker INP & NSU, Novosibirsk, Russia
S.A. Gromilov
Nikolaev IIC, Novosibirsk, Russia
Ya.A. Kolesnikov, A.M. Koshkarev, E.O. Sokolova
NSU, Novosibirsk, Russia
H. Sugawara
KEK, Ibaraki, Japan

Funding: This study was carried out with a grant from the Russian Science Foundation (project No. 14-32-00006-P) with the support of the Budker Institute of Nuclear Physics and Novosibirsk State University.
A vacuum-insulated tandem accelerator was used to observe in situ blistering during 2-MeV proton irradiation of metallic samples to a fluence of up to 6.7 10²⁰ cm². Samples consisting of copper of different purity, tantalum, and tantalum-copper compounds were placed on the proton beam path and forced to cool. The surface state of the samples was observed using a CCD camera with a remote microscope. Thermistors, a pyrometer, and an infrared camera were applied to measure the temperature of the samples during irradiation. After irradiation, the samples were analyzed on an X-ray diffractometer, laser and electron microscopes. The present study describes the experiment, presents the results obtained and notes their relevance and significance in the development of a lithium target for an accelerator-based neutron source, for use in boron neutron capture therapy of cancer.

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TUYGBD4

Beam Loss Background and Collimator Design in CEPC Double Ring

detector, scattering, background, simulation

632

S. Bai, J. Gao, H. Geng, D. Wang, Y. Wang, C.H. Yu, Y. Zhang
IHEP, 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. Radiative Bhabha scattering and Beamstrahlung effects are dominant mechanism of the beam induced backgrounds at CEPC due to the beam lifetime. In this paper, we evaluated the beam loss background in simulation and designed a series of collimators to suppress the radiation level on the machine and the detector.

Slides TUYGBD4 [0.791 MB]

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TUPAF015

Preliminary Test Results of the First ESS Elliptical Cryomodule Demonstrator

cavity, cryomodule, cryogenics, vacuum

691

F. Peauger, C. Arcambal, S. Berry, P. Bosland, E. Cenni, G. Devanz, T. Hamelin, O. Piquet, B. Renard, P. Sahuquet, T. Trublet
CEA/DRF/IRFU, Gif-sur-Yvette, France
C. Darve
ESS, Lund, Sweden
P. Michelato
INFN/LASA, Segrate (MI), Italy
G. Olivier
IPN, Orsay, France
J.P. Thermeau
Laboratoire APC, Paris, France

Two ESS elliptical cavities cryomodule prototypes are being developed and will be tested at CEA Saclay before starting the series production. This paper presents the preliminary test results of the first medium beta cavities cryomodule demonstrator M-ECCTD. The measurements of the cryogenic performances at 80 K and 2 K of the different cryomodule components and circuits are given. The first RF test results performed at low power are also reported.

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TUPAF023

The Beamlines of the CERN East Area Renovation Project

target, secondary-beams, experiment, operation

717

J. Bernhard, M. Bonnet, Q. Bouirek, D. Brethoux, B.D. Carlsen, A. Ebn Rahmoun, J. Etheridge, S. Evrard, L. Gatignon, E. Harrouch, M. Lazzaroni, M. Van Dijk, A. Watrigant
CERN, Geneva, Switzerland

The East Area at the Proton Synchrotron is one of CERN's longest running facilities for experiments, beam tests, and irradiations with a successful history of over 55 years. The facility serves more than 20 user teams for about 200 days of running each year and offers mixed secondary hadron, electron and muon beams of 0.5 GeV/c to 10 GeV/c. In addition, the primary proton beam or ion beam is transported to the irradiation facilities CHARM and IRRAD. Due to the steadily high user demand, the CERN management approved an upgrade and renovation of the facility to meet future beam test and physics requirements. New beam optics will assure a better transmission and purity of the secondary beams, now also with the possibility of highly pure electron, hadron or muon beams. The upgrade includes a pulsed powering scheme with energy recovering power supplies and new magnets, reducing both power and cooling requirements. Together with the building consolidation, this results in a considerably lower energy consumption. The renovation phase is scheduled during the technical stops between 2018 and 2020. We will give an overview of the project scope including upgrades and future beams.

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TUPAF074

Preliminary Modelling of Radiation Levels at the Fermilab PIP-II Linac

linac, proton, GUI, booster

898

L. Lari, C.M. Baffes, S.J. Dixon, N.V. Mokhov, I.L. Rakhno, I.S. Tropin
Fermilab, Batavia, Illinois, USA
F. Cerutti, L.S. Esposito, L. Lari
CERN, Geneva, Switzerland

PIP-II is the Fermilab's flagship project for providing powerful, high-intensity proton beams to the laboratory's experiments. The heart of PIP-II is an 800-MeV superconducting linac accelerator. It will be located in a new tunnel with new service buildings and connected to the present Booster through a new transfer line. To support the design of civil engineering and mechanical integration, this paper provides preliminary estimation of radiation level in the gallery at an operational beam loss limit of 0.1 W/m, by means of Monte Carlo calculations with FLUKA and MARS15 codes.

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TUPAF083

SIS100 Tunnel Design and Civil Construction Status

site, status, experiment, shielding

927

C. Omet, J. Falenski, H. Kisker, K. Konradt, P.J. Spiller
GSI, Darmstadt, Germany
A. Fischer
FAIR, Darmstadt, Germany

As the FAIR Project is proceeding, building designs have been frozen and the according work packages tendered. For the future FAIR main driver accelerator, SIS100, the 1.1 km long accelerator tunnel "T110", has been planned 17 m deep under ground. In this article, environmental boundary conditions, the chosen layout and the current status of civil construction is presented.

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TUPAF085

Status of Link Existing Facility Project for FAIR

linac, shielding, operation, synchrotron

934

J. Stadlmann, C. Omet, A. Schuhmann, P.J. Spiller
GSI, Darmstadt, Germany

The project "Link existing Facility", or GaF (GSI Anbindung an FAIR), is an important subproject of the overall FAIR facility. In order to serve as injector for SIS100, the main accelerator of FAIR, the existing GSI synchrotron SIS18 is undergoing an upgrade program leading to about 100 times higher beam intensities. Especially the foreseen operation with 4 GeV Protons with up to 5·10¹² protons per second increases the radiation protection requirements to such an extent that the existing radiation protection measures are no longer sufficient. The project consists of 78 individual measures. The four most substantial activities are the construction of a table-like structure to carry additional shielding. The creation of an opening and a first part of transfer tunnel for the beamlines towards the future FAIR campus. The preparation for the building, beam dump and connection of the FAIR proton injector. The incorporation of state-of-the-art radiation- and fire-protection measures into the present facilities including the a new technical building to house technical infrastructure. We report on the project status which is foreseen to finish mid-2018.

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TUPAK013

Geant4 Simulation of Radiation Effect on the Deflector of Extraction System in HUST SCC250

septum, proton, neutron, simulation

990

S. Hu, K. Fan, L.X.F. Li, Z.Y. Mei, Z.J. Zeng, L.G. Zhang
HUST, Wuhan, People's Republic of China

China has payed extensive attention to the development of proton therapy in recent years. When design a compact, high energy superconducting cyclotron for proton therapy， radiation effect induced by beam losses is a crucial consideration. Since the proton beam is extracted out of HUST SCC250 by electrostatic deflectors, the fierce interaction between proton beam and the deflector septum is the main cause of beam losses, which will bring about radiation effect leading to activation and coil quench. This paper presents simulation results of radiation effect by utilizing Geant4 Monte Carlo code. The energy depositions of proton beam in various septum materials are compared. Meanwhile, the yields, the ener-gy and angular distributions of secondary particles are investigated. Those simulation results based on radiation effect will provide us with valuable implications for the design of this superconducting cyclotron.

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TUPAL021

Evaluation of Activated Nuclides Due to Secondary Particles Produced in Stripper Foil in J-PARC RCS

proton, experiment, neutron, target

1048

M. Yoshimoto, S. Kato, M. Kinsho, K. Okabe, P.K. Saha, K. Yamamoto
JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan

Multi-turn charge-exchange beam injection is key technique to achieve the high intensity proton beam accelerators. In the J-PARC RCS, 400MeV H⁻ beams from the LINAC are converted to H⁺ beam with the stripper foils, and then injected into the ring. The stripper foil is irradiated by not only the injecting H⁻ beams but also the circulating H⁺ beams. The high energy and high power beam irradiation into the foil induces the nuclear reactions, and generated secondary neutrons and protons. These secondary particles causes high residual does around the stripper foil. Now, to identify species of secondary particles and to identify energies and emission angles, activation analysis method using the sample pieces is considered. In this presentation, we report the result of the evaluation of this activation analysis with PHITS codes.

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TUPAL045

Towards Operational Scalability for H⁻ Laser Assisted Charge Exchange

laser, experiment, cavity, operation

1110

S.M. Cousineau, A.V. Aleksandrov, T.V. Gorlov, Y. Liu, M.A. Plum, A. Rakhman, A.P. Shishlo
ORNL, Oak Ridge, Tennessee, USA
D.E. Johnson, S. Nagaitsev
Fermilab, Batavia, Illinois, USA
M.J. Kay
UTK, Knoxville, Tennessee, USA

The experimental development of H⁻ laser assisted charge exchange, a.k.a. laser stripping, has been ongoing at the SNS accelerator since 2006 in a three-phase approach. The first two phases associated with proof-of-principle and proof-of-practicality experiments have been successfully completed and demonstrated >95% H⁻ stripping efficiency for up to 10 us. The final phase is a proof-of-scalability stage to demonstrate that the method can be deployed for realistic beam duty factors. The experimental component of this effort is centered on achieving high efficiency stripping through the use of a laser power amplification scheme to recycle the macropulse laser light at the interaction point of the H⁻ stripping. Such a recycling cavity will be necessary for any future operational laser stripping system with at least millisecond duration H⁻ pulses. A second component of the proof-of-scalability phase is to develop a conceptual design for a realistic laser stripping scheme. The status of these efforts and challenges associated with deploying the recycling cavity into the laser stripping experiment will be described in this talk.

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TUPAL047

Strain Measurement in the Recent SNS Mercury Target with Gas Injection

target, injection, proton, neutron

1117

Y. Liu, W. Blokland, C.D. Long, S.N. Murray, B.W. Riemer, R.L. Sangrey, M. W. Wendel, D.E. Winder
ORNL, Oak Ridge, Tennessee, USA

Funding: ORNL is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. DOE.
High-radiation-tolerant fiber-optic strain sensors were recently developed to measure the transient proton-beam-induced strain profiles on the mercury target vessel at the Spallation Neutron Source (SNS). Here we report the strain measurement results and radiation-resistance performance on the latest SNS mercury target vessel equipped with helium gas injection. The results have demonstrated the efficacy of gas injection to reduce the cyclic stress on the target module.

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TUZGBF1

Superconducting Gantry for Carbon-Ion Radiotherapy

superconducting-magnet, quadrupole, dipole, MMI

1232

Y. Iwata, T. Furukawa, Y. Hara, S. Matsuba, T. Murakami, K. Noda, N. S. Saotome, S. Sato, T. Shirai
NIRS, Chiba-shi, Japan
N. Amemiya
Kyoto University, Kyoto, Japan
H. Arai, T. Fujimoto
AEC, Chiba, Japan
T.F. Fujita, K. Mizushima, Y. Saraya
National Institute of Radiological Sciences, Chiba, Japan
S. Matsuba
HSRC, Higashi-Hiroshima, Japan
T. Obana
NIFS, Gifu, Japan
T. Ogitsu
KEK, Ibaraki, Japan
T. Orikasa, S. Takayama
Toshiba, Yokohama, Japan
R. Tansho
QST-NIRS, Chiba, Japan

A superconducting magnet gantry has been used at HIMAC in NIRS, transporting beams for carbon ion radiotherapy. A second superconducting gantry, with a different design, is under construction in Yamagata University. This invited talk presents an overview of these gantry designs, their advantages for light ion radiotherapy, their operational experiences, and future perspectives for superconducting radiotherapy gantries.

Slides TUZGBF1 [26.678 MB]

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TUZGBF4

The South African Isotope Facility

target, cyclotron, isotope-production, proton

1240

J.L. Conradie, L.S. Anthony, F. Azaiez, S. Baard, R.A. Bark, A.H. Barnard, P. Beukes, J.I. Broodryk, J.C. Cornell, J.G. De Villiers, H. Du Plessis, W. Duckitt, D.T. Fourie, P.G. Gardiner, M.E. Hogan, I.H. Kohler, J.J. Lawrie, C. Lussi, N.R. Mantengu, R.H. McAlister, J. Mira, K.V. Mjali, H.W. Mostert, C. Naidoo, F. Nemulodi, M. Sakildien, V.F. Spannenberg, G.F. Steyn, N. Stodart, R.W. Thomae, M.J. Van Niekerk, P.A. van Schalkwyk
iThemba LABS, Somerset West, South Africa

iThemba LABS has developed a strategy to respond to the need to expand the research agenda of the facility, as well as to seize the opportunity to exploit the growing global demand for radioisotopes. This strategy will depend on the existing accelerator and isotope production infrastructure, as well as the acquisition of a cyclotron capable of accelerating protons to 70 MeV at beam currents in excess of 700 microampere. This development will be approached in two phases: Phase 1 will include the migration of the existing radioisotope production from the separated-sector cyclotron (SSC) to a new 70 MeV cyclotron. This rearrangement will increase the isotope production capability and also free up the SSC for research. In phase 2, beams of artificial isotopes will be produced at energies up to 5 MeV/nucleon to allow iThemba LABS to expand its research capabilities to new frontiers. The various different aspects of the proposed project will be discussed.

Slides TUZGBF4 [23.489 MB]

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TUPMF007

Cryogenic Testing and Initial Performance of a Helical Superconducting Undulator at the APS

vacuum, undulator, cryogenics, operation

1260

J.D. Fuerst, E. Gluskin, Q.B. Hasse, Y. Ivanyushenkov, M. Kasa, I. Kesgin, 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.
A helical superconducting undulator (HSCU) has been installed and is presently operational at the Advanced Photon Source (APS) at Argonne National Laboratory (ANL). We describe the final assembly and cryogenic test program which led to successful operation, representing the culmination of a two-year development effort. Details of the cryostat and cryogenic system design are presented along with as-installed performance data and a comparison with design expectations.

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TUPMF022

Electron Beam Scanning in the Delta-Type Undulators for Sirius

undulator, electron, polarization, storage-ring

1300

A. B. da Cruz, L. Liu
LNLS, Campinas, Brazil

We report on simulation studies to analyze the possibility of scanning the electron beam, and not scanning the sample, in CDI experiments using a Delta-Type undulator in the 3GeV Sirius electron storage ring presently under construction at LNLS. This would allow much faster scans in diffraction limited storage rings such as Sirius. We study displaced beam trajectories through the undulators and analyze the effects on the emitted radiation. It is possible to show that displacements on the order of ± 500 micrometers around the center will introduce variations in the radiation spectrum that are less that 1 per cent and thus acceptable for Coherent Diffraction Imaging experiments.

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TUPMF051

Generating Ultrashort X-Ray Pulse in a Diffraction-Limed Storage Ring by Phase-Merging Enhanced Harmonic Generation with Normal Modulator

bunching, laser, electron, undulator

1371

W. Liu, Y. Jiao
IHEP, Beijing, People's Republic of China

In recent years, the study of ultrafast processes has increased the demand for ultrashort pulses. The duration of the synchrotron radiation pulse is generally in the range of 10-100 ps, which cannot be used in the experiments of studying the ultrafast process. Thus it is interesting to explore a way of obtaining sub-picosecond radiation pulses in storage ring light sources. The phase-merging enhanced harmonic generation (PEHG) scheme using a transverse gradient undulator as the modulator can be used to generate coherent radiation at high harmonic, which is very suitable for the generating ultrashort pulses in a diffraction-limed storage ring (DLSR). This paper presents a new PEHG modulation scheme, using a normal undulator as the modulator. This scheme is technically easier to be realized in a DLSR. Simulation is performed to demonstrate the effectiveness of this method.

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TUPMF055

Phase Matching Application in Hard X-Ray Region of HEPS

undulator, brilliance, electron, photon

1386

X.Y. Li, Z. Duan, Y. Jiao, S.K. Tian
IHEP, Beijing, People's Republic of China

For the 6 meters long straight-section of HEPS, a double collinear double-cryogenic permanent magnet undulator(CPMU) structure is designed for high energy photon users to achieve higher brightness. Angular profiles of radiation produced by the double undulator configuration has been derived analytically. The efficiency of phase shifter on improving the brightness of double-CPMU is therefore evaluated with the beam energy spread is taken into account.

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TUPMF079

An Option to Generate Seeded FEL Radiation for FLASH1

FEL, electron, laser, undulator

1448

V. Grattoni, R.W. Aßmann, J. Bödewadt, I. Hartl, C. Lechner, B. Manschwetus, M.M. Mohammad Kazemi
DESY, Hamburg, Germany
W. Hillert, V. Miltchev, J. Roßbach
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
S. Khan, T. Plath
DELTA, Dortmund, Germany

The FLASH free-electron laser (FEL) at DESY is currently operated in self-amplified spontaneous emission (SASE) mode in both beamlines FLASH1 and FLASH2. Seeding offers unique properties for the FEL pulse, such as full coherence, spectral and temporal stability. In this contribution, possible ways to carry the seeded FEL radiation to the user hall are presented with analytical considerations and simulations. For this, components of the sFLASH seeding experiment are used.

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TUPML026

Multi-photon Photoemission and Ultrafast Electron Heating in Cu Photocathodes at Threshold

electron, photon, cathode, laser

1593

J. Bae, L. Cultrera
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
I.V. Bazarov, J.M. Maxson
Cornell University, Ithaca, New York, USA
S.S. Karkare, H.A. Padmore
LBNL, Berkeley, California, USA
P. Musumeci, X.L. Shen
UCLA, Los Angeles, California, USA

Funding: U.S. National Science Foundation under award PHY-1549132, the Center for Bright Beams.
Operating photocathodes near the photoemission threshold holds the promise of yielding small intrinsic emittance, at the cost of significantly reduced quantum efficiency. In modern femtosecond photoemission electron sources, this requires a very high intensity (10s of GW/cm²) to extract a useful quantity of electrons. At this intensity, the electron occupation function is far from equilibrium and evolves rapidly on sub-ps timescales. Thus, ultrafast laser heating and multiphoton photoemission effects may play a significant role in emission, thereby increasing the minimum achievable emittance. In this work, we use a Boltzmann equation approach to calculate the non-equilibrium occupation function evolution in time for a copper photocathode, yielding a prediction of quantum efficiency and mean transverse energy as a function of input intensity.

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TUPML035

FELs Driven by Laser Plasma Accelerators Operated with Transverse Gradient Undulators

undulator, FEL, electron, laser

1615

F. Jafarinia, R.W. Aßmann, F. Burkart, U. Dorda, C. Lechner, B. Marchetti, R. Rossmanith, P.A. Walker
DESY, Hamburg, Germany
A. Bernhard, R. Rossmanith
KIT, Karlsruhe, Germany

Laser Plasma Accelerators produce beams with a significantly higher energy spread (up to a few percent) compared to conventional electron sources. The high energy spread increases significantly the gain length when used for an FEL. In order to reduce the gain length of the FEL the Transverse Gradient Undulators (TGUs) instead of conventional undulators were proposed. In this paper the limits of this concept are discussed using a modified Version of the GENESIS program*.
*Zhirong Huang et al., Phys. Rev. Lett., 109, 204801

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TUPML054

Microbeam Irradiation System with a Dielectric Laser Accelerator for Radiobiology Research

laser, electron, accelerating-gradient, cavity

1664

K. Koyama
KEK, Ibaraki, Japan
Z. Chen
The University of Tokyo, Tokyo, Japan
T. Takahashi
The University of Tokyo, The School of Engineering, Tokyo, Japan
M. Uesaka
The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan

Funding: This work was supported by KAKENHI (Grant-in-Aid for Scientific Research)15H03595 and partly supported by NIMS Nanofabrication Platform in Nanotechnology Platform Project sponsored by the MEXT, Japan.
A laser micro-irradiation (LMI) system is widely used in the field of radiobiology because of its acceptably small size. However, damage in a cell nucleus caused by the LMI system does not necessarily simulate a radiation effect. If the laser of the LMI system is replaced with a small-scale 1MeV-class accelerator such as a dielectric laser accelerator (DLA), experiments might be performed under conditions that are more realistic. The desirable configuration of the DLA for a compact micro-beam irradiation system is that laser pulses are transported to a dielectric structure by single-mode optical fibers and the laser energy is accumulated in an accelerator channel. The long and low-intensity laser pulse of 100 MW/cm², 10ps and a resonator with Q=10⁴ are capable of producing the light intensity of 1 TW/cm². The long laser pulse, i.e., low laser induced damage threshold intensity, decreases the acceleration gradient to about 1/3 of the ultra-short pulse irradiation of 100 fs. The length of the accelerator at long-laser pulse might be within the allowable range of several cm. The resonator scheme is useful only for the sub-relativistic regime because of the acceleration gradient.

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WEXGBD1

Development of Very Short Period Undulators

undulator, electron, vacuum, factory

1735

S. Yamamoto
KEK, Ibaraki, Japan

Scientists and engineers at KEK have developed undulator magnets having very short period lengths. Magnet plates 100mm and 152mm long with 4-mm period length have been successfully fabricated. They produce an undulator field of approximately 4kG at a gap of 1.6mm. The magnetic field characterization shows that the undulator field is satisfactory in quality for a very short period undulator. KEK has recently installed a short-period undulator at a 50-MeV linac and observed a first light, and will soon start an experiment using a short-period undulator with laser-accelerated electrons for future table-top XFELs. This invited talk summarizes the current status, and experimental activities and results related to short-period undulators and table-top FELs.

Slides WEXGBD1 [3.515 MB]

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WEXGBE3

IBS Studies at BESSY II and MLS

simulation, emittance, scattering, damping

1755

T. Mertens
Helmholtz-Zentrum Berlin für Materialien und Energie GmbH (HZB), Berlin, Germany
T. Atkinson, J. Feikes, P. Goslawski, J.G. Hwang, A. Jankowiak, J. Li, D. Malyutin, Y. Petenev, M. Ries, I. Seiler
HZB, Berlin, Germany

Intrabeam Scattering (IBS) effects will become a limiting factor for the attainable emittances and single-bunch currents in future electron storage rings and light sources. IBS studies were performed for BESSY II at the Helmholtz-Zentrum Berlin (HZB) and for the Metrology Light Source (MLS) at the Physikalisch-Technische Bundesanstalt (PTB) to quantify the IBS contributions to equilibrium beam sizes in these machines and make predictions for the BESSY II upgrade project, BESSY VSR. The energy dependence of IBS effects (γ −4 ) makes especially the MLS machine susceptible to IBS effects due to the relatively low energy ranges at which it can be operated (50 MeV-630 MeV). We compare experimental data with simulations and present IBS simulation results for BESSY VSR.

Slides WEXGBE3 [0.916 MB]

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WEYGBD2

Status of the Radiation Damage on the European XFEL Undulator Systems

undulator, FEL, operation, electron

1776

F. Wolff-Fabris, J. Pflüger
XFEL. EU, Schenefeld, Germany
F. Hellberg
Stockholm University, Stockholm, Sweden
F. Schmidt-Föhre
DESY, Hamburg, Germany

The European XFEL GmbH is a new X-ray FEL user facility and started lasing in 2017. Three gap movable SASE Undulator Systems are designed to produce FELs with tunable wavelengths from 0.05 to 5.2nm [*,**]. A total of 91 5-m long undulator segments based on hybrid NdFeB permanent magnet technology were tuned respecting tight specifications. Radiation damage due to machine operation affects the magnetic properties of the segments and the quality of the SASE process. An array of dosimeters based on Radfets [***] and Gafchromic films monitors the absorbed doses in every undulator segment and each SASE system is equipped with a 12mm gap diagnostic undulator (DU) which is magnetically re-measured during machine maintenance weeks. Doses up to 4 kGy have been observed and magnetic field degradation higher than 3% is measured. These results permit to estimate the effects of radiation damage and life expectancy of the Undulator Systems based on the precise K-parameter determination for beam operation. We will present the results of magnetic re-measurements on the Undulator Systems, the details of the effects of radiation damage and future plans to maximize the beam quality and operation.
* M. Altarelli et al., Tech. Design Rep. DESY 2006-097, July 2007.
** E. Schneidmiller et al., Eur. XFEL Tech. Rep. TR-2011-006, Sep. 2011.
*** F. Schmidt-Föhre et al., IPAC-2018 contribution.

Slides WEYGBD2 [3.670 MB]

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WEYGBE1

Suppressing CSR Microbunching in Recirculation Arcs

bunching, dipole, lattice, emittance

1784

C.-Y. Tsai
SLAC, Menlo Park, California, USA

We provide sufficient conditions for suppression of CSR-induced microbunching instability along transport or recirculation arcs. The example lattices include low-energy (∼100 MeV) and high-energy (∼1 GeV) recirculation arcs, and medium-energy compressor arcs. Our studies show that lattices satisfying the proposed conditions indeed have microbunching gain suppressed. Beam current dependencies of maximal CSR microbunching gains are also demonstrated, which should help outline a beam line design for different scales of nominal currents. We expect this analysis can improve future lattice design.

Slides WEYGBE1 [10.975 MB]

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WEPAF005

A Fast Beam Interlock System for the Advanced Photon Source Particle Accumulator Ring

photon, operation, shielding, detector

1815

J.C. Dooling, M. Borland, K.C. Harkay, R.T. Keane, B.J. Micklich, C. Yao
ANL, Argonne, Illinois, USA

Funding: Work supported by the U.S. Department of Energy, Office of Science, Of- fice of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A fast beam interlock system for the Advanced Photon Source (APS) Particle Accumulator Ring (PAR) based on the detection of Cerenkov light is proposed for high-charge operations associated with the APS Upgrade (APS-U). Light is generated from lost electrons passing through high-purity, fused-silica fiber optic cable. The cable acts as both radiator and light pipe to a Pb-shielded photomultiplier tube. Results from a prototype installation along the PAR south wall have shown excellent sensitivity, linearity, and reproducibility after 10,000 hours of operation to date with little change in the optical transmission of the fiber. High sensitivity allows more accurate measurement of low-level loss than possible with current monitors. The radiator and detector provide a much faster response than the installed gamma or neutron detectors. A faster, more accurate response to electron loss will be important as we run with higher charge and consider operating at increased energy for APS-U. Initial calibration measurements of the prototype system with radiation monitors for various loss scenarios are discussed. Comparison of the scenarios with simulations are presented.

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WEPAF012

Improvements of NSLS-II X-ray Diagnostic Beamlines

emittance, storage-ring, vacuum, photon

1837

W.X. Cheng, B. Bacha, B.N. Kosciuk, D. Padrazo Jr
BNL, Upton, Long Island, New York, USA

Funding: Work supported by DOE contract No: DE-SC0012704
There are two X-ray diagnostic beamlines (XDB) developed at NSLS-II storage ring to measure emittance, energy spread, and other machine parameters. The first beamline utilizes a soft bending magnet radiation has been in operation since 2014. The tungsten pinhole originally located in the air had corrosion issue. The beamline has been improved by extending the vacuum to the imaging system. The second X-ray pinhole beamline using three-pole wiggler (TPW) radiation has been constructed and commissioned recently. Energy spread is able to be precisely measured due to large dispersion at the source point. A gated camera is equipped with the new beamline to acquire profiles within one turn. Recent operation experience and beam measurements will be presented in this paper.

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WEPAF035

Coherent Diffraction Radiation Imaging as an RMS Bunch Length Monitor

FEL, target, experiment, detector

1895

J. Wolfenden, R.B. Fiorito, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
R.B. Fiorito, C.P. Welsch, J. Wolfenden
The University of Liverpool, Liverpool, United Kingdom
T.H. Pacey, T.H. Pacey
UMAN, Manchester, United Kingdom
A.G. Shkvarunets
UMD, College Park, Maryland, USA

Funding: This work was supported by the EU under Grant Agreement No. 624890 and the STFC Cockcroft Institute core Grant No. ST/G008248/1.
High-resolution bunch length measurement is of the utmost importance for current and future generations of light sources and linacs. It is also key to the optimisation of the final beam quality in plasma-based acceleration. We present progress in the development of a novel RMS bunch length monitor based on imaging the coherent diffraction radiation (CDR) produced by a non-invasive circular aperture. Due to the bunch lengths involved, the radiation produced is in the THz range. This has led to the development of a novel THz imaging system, which can be applied to low energy electron beams. For high energy beams the imaging system can be used as a single shot technique. Simulation results show that the profile of a CDR image of a beam is sensitive to bunch length and can thus be used as a diagnostic. The associated benefits of this imaging distribution methodology over the typical angular distribution measurement are discussed. Plans for experiments conducted at the SwissFEL (PSI, Switzerland), along with plans for future high energy single shot measurements are also presented.

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WEPAF036

Energy Independence in Optical Transition Radiation Imaging

simulation, electron, diagnostics, optics

1898

J. Wolfenden, R.B. Fiorito, C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom
R.B. Fiorito, C.P. Welsch, J. Wolfenden
The University of Liverpool, Liverpool, United Kingdom

Funding: This work was supported by the EU under Grant Agreement No. 624890 and the STFC Cockcroft Institute core Grant No. ST/G008248/1.
The exploitation of optical transition radiation (OTR) in imaging-based diagnostics for charged particle beams is a well-established technique. Simulations of the expected OTR transverse beam profiles are therefore important in both the design of such imaging systems and the analysis of the data. Simulating OTR images is relatively straightforward for low energy electron beams. However, in the near future electron machines will be using high-energy and low-emittance beams. Using such parameters can be challenging to simulate, and can be limiting in their account of practical factors, e.g. chromatic aberrations. In this work we show systematically that the use of low-energy parameters in high-energy OTR image simulations induces little deviation in the resulting transverse beam profiles. Simulations therefore become much easier to perform, and further analysis may be performed. This opens up exciting opportunities to perform simulations quicker and with reduced demands on the computation requirements. It will be shown in this contribution how this approach will enable enhanced ways to optimize OTR diagnostics.

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WEPAF060

Non-Invasive Bunch Length Diagnostics for High Intensity Beams

detector, electron, real-time, simulation

1964

S.V. Kuzikov, S.P. Antipov
Euclid TechLabs, LLC, Solon, Ohio, USA
S.V. Kuzikov, A.A. Vikharev
IAP/RAS, Nizhny Novgorod, Russia

Modern particle accelerators utilize photoinjectors and compression schemes to produce short high peak current electron bunches for various applications like x-ray free electron lasers, high gradient beam driven acceleration and others. Bunch length detection is a desired diagnostics for such machines. In this paper we describe a non-invasive, real-time detector which can be retrofitted into an existing beamline and measure the bunch length in real time using interferometric methods. Diffraction radiation is the mechanism to be used to produce a measurable signal without intercepting the beam. This became possible as sensitivity of pyrodetectors improved over the years, while peak beam power grew. For high peak current beams there is a possibility of a single shot measurement. This can be done with a pair of closely placed vacuum breaks that create a spatial correlation of the generated signals which can be measured by a pyro-detector array or a THz camera. The bunch length is determined from the correlation data using an iterative beam profile recovery algorithm.

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WEPAF074

Non-invasive Beam Diagnostics with Cherenkov Diffraction Radiation

photon, detector, electron, plasma

2005

T. Lefèvre, M. Bergamaschi, O.R. Jones, R. Kieffer, S. Mazzoni
CERN, Geneva, Switzerland
L.Y. Bartnik, M.G. Billing, Y.B.P. Bordlemay Padilla, J.V. Conway, M.J. Forster, J.P. Shanks, S. Wang
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
M. Bergamaschi, P. Karataev
Royal Holloway, University of London, Surrey, United Kingdom
V.V. Bleko, A.S. Konkov, J.S. Markova, A. Potylitsyn
TPU, Tomsk, Russia
L. Bobb
DLS, Oxfordshire, United Kingdom
K. Lekomtsev
JAI, Egham, Surrey, United Kingdom

Based on recent measurements of incoherent Cherenkov Diffraction Radiation (ChDR) performed on the Cornell Electron Storage Ring, we present here a concept for the centering of charged particle beams when passing close to dielectric material. This would find applications as beam instrumentation in dielectric capillary tubes, typically used in novel accelerating technologies, as well as in collimators using bent crystals for high-energy, high-intensity hadron beams, such as the Large Hadron Collid-er or Future Circular Collider. As a charged particle beam travels at a distance of a few mm or less from the surface of a dielectric material, incoherent ChDR is produced inside the dielectric. The photons are emitted at a large and well-defined angle that allows their detection with a limited contribution of background light. A set of ChDR detectors distributed around a dielectric would enable both the beam position and tilt angle to be measured with a good resolution.

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WEPAF081

An Enhanced Quench Detection System for Main Quadrupole Magnets in the Large Hadron Collider

quadrupole, monitoring, controls, power-supply

2032

J. Spasic, D.O. Calcoen, R. Denz, V. Froidbise, S. Georgakakis, T. Podzorny, A.P. Siemko, J. Steckert
CERN, Geneva, Switzerland

To further improve the performance and reliability of the quench detection system (QDS) for main quadrupole magnets in the Large Hadron Collider (LHC), there is a planned upgrade of the system during the long shutdown period of the LHC in 2019-2020. While improving the already existing functionalities of quench detection for quadrupole magnets and field-bus data acquisition, the enhanced QDS will incorporate new functionalities to strengthen and improve the system operation and maintenance. The new functionalities comprise quench heater supervision, interlock loop monitoring, power cycling possibility for the whole QDS and its data acquisition part, monitoring and synchronization of trigger signals, and monitoring of power supplies. In addition, the system will have two redundant power supply feeds. Given that the enhanced QDS units will replace the existing QDS units in the LHC tunnel, the units will be exposed to elevated levels of ionizing radiation. Therefore, it is necessary to design a radiation tolerant detection system. In this work, an overview of the design solution for such enhanced QDS is presented.

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WEPAF082

A Systematic Analysis of the Prompt Dose Distribution at the Large Hadron Collider

operation, luminosity, experiment, proton

2036

O. Stein, K. Bilko, M. Brugger, S. Danzeca, D. Di Francesca, R. Garcia Alia, Y. Kadi, G. Li Vecchi, C. Martinella
CERN, Geneva, Switzerland

During the operation of the Large Hadron Collider (LHC) the continuous particle losses create a mixed particle radiation field in the LHC tunnel and the adjacent caverns. Exposed electronics and accelerator components show dose dependent accelerated aging effects. In order to achieve an optimal lifetime associated to radiation damage, the position of the equipment is chosen in dependency of the amplitude of the radiation fields. Based on the continuous analysis of the data from more than 3900 ionisation chamber beam loss monitors the evolution of the radiation levels is monitored during the accelerator operation. Normalising the radiation fields with either the integrated luminosity or the integrated intensities allows extrapolating the radiation levels of future accelerator operation. In this paper, the general radiation levels in the arcs and the insertion regions at the LHC and their evolution will be presented. The changes in the prompt dose distribution along the LHC between the operation in 2016 and 2017 will be discussed. The impact of different accelerator settings on the local dose distribution will be addressed as well.

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WEPAF083

Distributed Optical Fiber Radiation Sensing at CERN

synchrotron, distributed, operation, extraction

2039

G. Li Vecchi, M. Brugger, S. Danzeca, D. Di Francesca, R. Ferraro, Y. Kadi, O. Stein
CERN, Geneva, Switzerland
S. Girard
Univ-Lyon Laboratoire H. Curien, UMR CNRS 5516, Saint Etienne, France

The CERN's accelerator tunnels are associated with very complex mixed field radiation environments. Radiation degrades electronic components and directly affects their lifetimes causing failures that contribute to the machine downtime periods. In our contribution, we will report on the development and first employment of a Distributed Optical Fiber Radiation Sensor (DOFRS) at CERN. The most interesting feature of DOFRS technology is to provide an online and spatially distributed map of the dose levels in large machines with spatial resolution of the order of one meter. This fiber based dose sensor will provide valuable information in addition to the currently installed active and passive dosimeters. After demonstrating the working principle of DOFRS*, the first operational prototype was installed in the Proton Synchrotron Booster during last 2016/17 end-of-the-year technical stop. The DOFRS has been acquiring data successfully since the beginning of 2017 operations. The performances that were achieved by the first prototype will be discussed in the final contribution. The DOFRS measurements will also be bench-marked to the results provided by other punctual dosimeters.
*I. Toccafondo et al., 'Distributed Optical Fiber Radiation Sensing in a Mixed-Field Radiation Environment at CERN,' J. Lightw. Technol. 35, 3303, 3310, 2017.

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WEPAG003

Hadron Beam Monitor Design with Gas-Filled RF Resonators in Intense Neutrino Source

cavity, hadron, scattering, target

2067

M.D. Balcazar, K. Yonehara
Fermilab, Batavia, Illinois, USA

Funding: Work supported by Fermilab Research Alliance, LLC under Contract No. DE-AC02-07CH11359 and DOE STTR Grant, No. DE-SC0013795.
For the future Long Baseline Neutrino Facility at Fermilab, a new radiation-robust hadron beam profile monitor has been proposed consisting of an interface of gas-filled radiofrequency cavity detectors in the backward region of the LBNF decay pipe. A tailored monitor layout will be used along with the new RF instrumentation. Proposed designs for the detector configuration include a variety of radially symmetric arrangements of RF resonators located at the position of maximum gradient in the beam distribution across the monitor. Until the final detector cavities are available, a prototype tunable Q-factor RF cavity will provide functional emulation for studies of the monitor layout configurations presented here.

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WEPAL004

The Algorithm Research of DBPM for HEPS

synchrotron, synchrotron-radiation, collider, injection

2147

F. Liu, J.S. Cao, Y.Y. Du, S.J. Wei
IHEP, People's Republic of China

The High Energy Photon Source (HEPS) is a 6-GeV, low-emittance, 1300m scale new generation photon source to be built in China [1]. As a key component, digital beam positon monitor (DBPM) needs to make the beam slow acquisition's resolution up to 0.1um. Because of the high requirements and large expenses, we designed our own DBPM system. In this paper, I will present the algorithm of our BPM. The algorithm is based on Discrete Fourier Transform (DFT) method and tested in BEPCII with using our own designed hardware. The Turn-by-Turn's resolution tested in BEPCII is 0.62um (STD value, 65080 counts, 1.2432MHz), the fast acquisition's resolution is 0.32um (STD value, 65080 counts, 10kHz), the slow acquisition's resolution is 0.18um (STD value, 65080 counts, 10Hz).

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WEPAL011

iPipe: An Innovative Fiber Optic Monitoring System for Beam Induced Heating on Accelerator Pipes

monitoring, experiment, operation, detector

2166

F. Fienga, S. Buontempo, M.R. Masullo
INFN-Napoli, Napoli, Italy
A. Ball, N. Beni, B. Salvant, W. Zeuner
CERN, Geneva, Switzerland
G. Breglio, A. Irace
University of Napoli Federico II, Napoli, Italy
Z. Szillasi
ATOMKI, Debrecen, Hungary
V.G. Vaccaro
Naples University Federico II and INFN, Napoli, Italy

The iPipe project consists in the instrumentation, with Fiber Bragg Grating sensors (FBGs), of the beam pipe of the CMS experiment, which is part of the LHC. Being spectrally encoded, the FBGs are not sensitive to electromagnetic interference and broadband-radiation-induced losses. These characteristics allow to realize long distance punctual sensing systems, capable to operate in harsh environments like the underground experimental and accelerator facilities at CERN. The iPipe secures the measurement of any deformation induced on the central beam pipe by any motion in the CMS detector due to element displacement or to magnetic field induced deformations. Moreover, the iPipe FBG temperature sensors represent a unique solution to monitor the beam pipe thermal behavior during the various operational and maintenance phases. This paper reports the use of the iPipe to measure the beam induced heating on the CMS vacuum chamber throughout 2016 and 2017. A first comparison between the measurements and the heat load predicted from beam induced RF heating due to the coupling impedance of the CMS pipe is also reported.

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WEPAL013

Design of the Diagnostic Stations for the ELI-NP Compton Gamma Source

electron, optics, linac, simulation

2173

M. Marongiu
INFN-Roma, Roma, Italy
M. Castellano, E. Chiadroni, G. Di Pirro, G. Franzini, A. Giribono, V. Shpakov, A. Stella, A. Variola
INFN/LNF, Frascati (Roma), Italy
A. Cianchi
Università di Roma II Tor Vergata, Roma, Italy
A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy

A high brightness electron Linac is being built in the Compton Gamma Source at the ELI Nuclear Physics facility in Romania. To achieve the design luminosity, a train of 32 bunches, 16 ns spaced, with a nominal charge of 250 pC will collide with the laser beam in the interaction point. Electron beam spot size is measured with optical transition radiation (OTR) profile monitors. Furthermore, OTR angular distribution strongly depends on beam energy. Since OTR screens are typically placed in several positions along the Linac to monitor beam envelope, one may perform a distributed energy measurement along the machine. This will be useful, for instance, during the commissioning phase of the GBS in order to verify the correct functionality of the C-Band accelerating structures, due to the fact that there are OTR screens after each accelerating module. This paper deals with the studies of different optic configurations to achieve the field of view, resolution and accuracy in order to measure the energy of the beam. Several configurations of the optical detection line will be studied with simulation tools (e.g. Zemax).

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WEPAL015

Improvement of Motor Control System in J-PARC Linac and RCS

controls, operation, hardware, PLC

2180

H. Takahashi, A. Miura, Y. Sawabe, M. Yoshimoto
JAEA/J-PARC, Tokai-mura, Japan
M. Kawase, T. Suzuki
Mitsubishi Electric System & Service Co., Ltd, Tsukuba, Japan

In J-PARC, at the Linac wire scanner, the RCS collimator, and etc., a motor control system by VME is constructed as a drive system of them. Since the malfunction of operation occurred in the control system of the RCS collimator drive system in 2016, we decided to improve the motor control system. As a cause of malfunction, it is considered that aging of control equipment is one of them as J-PARC has been operated for more than 10 years. However, the defect did not occur in the reproduction test. Therefore, it can be considered that a malfunction occurred in the VME control system due to abnormality of the semiconductor element due to radiation ray. Then, in the improved motor control system, PLC with FA* specification with high reliability was adopted as the control device. Also, in case of unexpected event that a malfunction occurred in the PLC, the emergency stop mechanism was developed to stop the drive system by the signal of the limit switch, and a system incorporating it was constructed. In this paper, we show the inference of cause of the malfunction and details the improved motor control system with high safety.
* Factory Automation

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WEPAL026

High Repetition Rate, Single-Shot Electro-Optical Monitoring of Longitudinal Electron Bunch Dynamics Using the Linear Array Detector KALYPSO

electron, storage-ring, laser, FEL

2216

G. Niehues, E. Blomley, M. Brosi, E. Bründermann, M. Caselle, S. Funkner, A.-S. Müller, M.J. Nasse, L. Rota, M. Schuh, P. Schönfeldt, M. Weber
KIT, Eggenstein-Leopoldshafen, Germany
N. Hiller
PSI, Villigen PSI, Switzerland

Funding: This work is funded by the BMBF contract numbers: 05K13VKA and 05K16VKA.
High repetition rate diagnostics are required when detecting single-shot electro-optical (EO) bunch profiles. The KIT storage ring KARA (KArlsruhe Research Accelerator) is the first storage ring in the world that has a near-field EO bunch-profile monitor in operation. By imprinting longitudinal electron bunch profiles onto chirped laser pulses, single-shot detection is feasible. However, limitations of available detection systems are challenging: The constraints are either given by the repetition rate or the duration of the consecutive acquisitions. Two strategies can overcome these limitations: Based on the photonic time-stretch method, the ps laser pulses can be stretched to the ns range using km long fibers. The readout with a high-bandwidth oscilloscope then enables a single-shot detection at high repetition rates. The other strategy is the development of dedicated ultra-fast photodetector arrays allowing direct detection of the ps pulses at MHz repetition rates. We developed KALYPSO, a linear detector array with a DAQ allowing to record high data-rates over long time scales. Here, we present recent results of studies of the longitudinal electron bunch dynamics using KALYPSO.

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WEPAL027

Filling Pattern Measurements Using Dead-Time Corrected Single Photon Counting

photon, synchrotron, storage-ring, data-analysis

2219

B. Kehrer, E. Blomley, M. Brosi, E. Bründermann, A.-S. Müller, M. Schuh, P. Schönfeldt, J.L. Steinmann
KIT, Karlsruhe, Germany

Time-correlated single photon counting (TCSPC) is a versatile tool for various accelerator diagnostics aspects. Amongst others it allows a precise determination of the filling pattern. At the visible light diagnostics port at the Karlsruhe Research Accelerator (KARA), the KIT storage ring, a Single-Photon Avalanche Diode (SPAD) in combination with a histogramming device (PicoHarp) is used. To compensate for possible dead-time effects, a correction scheme was developed and tested successfully. The compensation increases the dynamic range in which accurate measurements are possible and avoids distortion of the measured filling pattern. This contribution presents the experimental setup, as well as a series of benchmark measurements.

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WEPAL028

Study of the Influence of the CSR Impedance on the Synchronous Phase Shift at KARA

impedance, synchrotron, simulation, storage-ring

2223

P. Schönfeldt, E. Blomley, M. Brosi, E. Bründermann, J. Gethmann, B. Kehrer, A.-S. Müller, A.I. Papash, J.L. Steinmann
KIT, Karlsruhe, Germany

Funding: This work has been supported by the German Federal Ministry of Education and Research (Grant No. 05K16VKA) and the Helmholtz Association (Contract No. VH-NG-320).
Measurements of the bunch current dependent synchronous phase shift are a standard method to characterize the impedance of a storage ring. To study this shift, different experimental approaches can be used. In this contribution, we first derive the phase shift caused by the impedance describing the emission of coherent synchrotron radiation (CSR) based on numerical simulations of the longitudinal phase space. The predicted shift is compared to measurement results obtained by time-correlated single photon counting.

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WEPAL034

Bunch Length Measurements Using Coherent Smith-Purcell Radiation With Several Gratings at CLIO

booster, detector, laser, experiment

2239

N. Delerue, S. Jenzer, V. Khodnevych, A. Migayron
LAL, Orsay, France
J.P. Berthet, N. Jestin, J.-M. Ortega, R. Prazeres
CLIO/ELISE/LCP, Orsay, France

Funding: Financially supported by the Université Paris-Sud (programme "attractivité"), by the French ANR (contract ANR-12-JS05-0003-01) and by IN2P3.
Coherent Smith Purcell radiation allows the measurement of a beam longitudinal profile through the study of the emission spectrum of the radiation emitted when a grating is brought close from the beam. In order to increase the dynamic range of our measurements we have used several gratings and we report on the measured bunch form factor using this technique. We report on these measurements and on the background rejection used.

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WEPAL055

TPS Beam Trip Analysis and Dose Distribution

kicker, SRF, neutron, storage-ring

2302

B.Y. Chen, F.Y. Chang, S. Fann, C.S. Huang, C.H. Kuo, T.Y. Lee, C.C. Liang, W.Y. Lin, Y.C. Lin, Y.-C. Liu
NSRRC, Hsinchu, Taiwan

Failure analysis during TPS users operation is im-portant to improve the performance of the TPS storage ring. In this report, we discuss the particular radiation dose patterns, relevant to different beam trips, and the development of a tool to help us analyse this dose distri-bution. We will use this analysing tool to train our ability for future failure analysis to shorten the time it takes to find the problem.

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WEPAL058

Beam Loss Studies at the Taiwan Photon Source

injection, vacuum, scattering, undulator

2309

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

PIN-photodiodes and RadFETs are installed in the storage ring of the Taiwan Photon Source (TPS) to study beam loss distributions and mechanisms. In the highest dose area, the radiation comes mainly from hard X-rays produced by synchrotron bending magnets. During beam cleaning and after replacing a vacuum chamber, losses due to inelastic Coulomb scattering occur mostly downstream from bending magnets while elastic scattering causes electrons to get lost mainly after an elliptically polarizing undulator which has a limited vertical aperture. During the injection period, the beam loss pattern can be changed by modifying injection conditions or lattice settings. The beam loss usually happens in the injection section and small-aperture section. The injection efficiency can be improved by minimizing the detected injection loss.

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WEPMF009

Influence of Argon-Ion Irradiation on Field Emission from Polycrystalline Cu and Large-Grain NB Surfaces

niobium, experiment, cavity, vacuum

2384

S. Soykarci
University of Wuppertal, Wuppertal, Germany
D. Lützenkirchen-Hecht, V. Porshyn, P. Serbun
Bergische Universität Wuppertal, Wuppertal, Germany

Funding: This work is funded by the BMBF project 05H15PXRB1.
In the present work, systematic investigations of the enhanced field emission (EFE) from polycrystalline copper and large grain niobium surfaces before and after argon-ion irradiation with an energy of 5 keV were performed with a variation of the irradiation time. Results show that the suppression of the EFE might be achievable.

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WEPMF045

Performance of the Prototype SRF Half-Wave-Resonators Tested at Cornell for the RAON Project

cavity, SRF, multipactoring, pick-up

2468

M. Ge, F. Furuta, T. Gruber, S.W. Hartman, M. Liepe, J.T. Maniscalco, T.I. O'Connell, P.J. Pamel, J. Sears, V. Veshcherevich
Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
B.H. Choi, J. Joo, J.W. Kim, W.K. Kim, J. Lee, I. Shin
IBS, Daejeon, Republic of Korea

Two prototype superconducting half-wave-resonator (162.5 MHz and β=0.12) for the RAON project have been successfully tested at Cornell University. Detailed vertical performance testing included (1) test of the bare cavity without the helium tank, and (2) test of the dressed cavity with a helium tank. In this paper, we report on the development of the test infrastructure, test results, and performance data analysis, showing that the specifications for RAON were met.

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WEPMF053

XFEL Modulators with Pulse Cables

FEL, operation, klystron, linac

2487

H.-J. Eckoldt, S. Choroba, T. Grevsmühl, A. Hauberg, J. Havlicek, N. Heidbrook, K. Machau, N. Ngada
DESY, Hamburg, Germany
M. Frei, S.G. Keens, T.H. Strittmatter
Ampegon AG, Turgi, Switzerland
H. Leich
DESY Zeuthen, Zeuthen, Germany

The modulators of the European XFEL produce high voltage, at the 10kV level, having a power of up to 16.8 MW for 1.54 ms. The operation frequency of the super-conducting inac is 10 Hz. The series production of the 29 modulators started in 2012. The first modulator began operation in 2014 and the start of linac was beginning 2017. The R&D phase for the modulators started directly with the development of superconducting cavities. Besides the pulse generation, the modulator had to suppress the 10 Hz repetition rate in order not to disturb the grid. Another unique demand was the development of pulse cables. Since the power RF had to be generated in the tunnel, the klystrons were installed near the cavities. However, the modulators had to be installed outside of the tunnel for space, maintenance reasons and radiation concerns. This transmission of high power pulses via long cables is unique in the world and the suppression of EMI effects was mandatory. During the first year operation no EMI disturbances of other systems were detected and the modulator system works as expected.

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WEPMF057

PETRA III Vacuum System - Experiences from the First Decade of Operation

vacuum, operation, photon, experiment

2499

L. Lilje, R. Bospflug, N. Plambeck
DESY, Hamburg, Germany

In 2008 the construction of the PETRA III vacuum system started. A year later the first photons were delivered to initial experiments and in 2010 the user operation started. In this paper the operation of the vacuum system will be reviewed. Some of the lessons learned in the initial phase will be presented as well as the main upgrades since then. By now the vacuum system has shown a very high reliability and shows no significant impact on the availability of the machine.

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WEPMF081

Mechanical Strain Measurements Based on Fiber Bragg Grating Down to Cryogenic Temperature - R&D Study and Applications

cryogenics, superconducting-magnet, GUI, experiment

2572

M. Guinchard, A. Bertarelli, L. Bianchi, F.B. Boyer, M. Cabon, M. Calviani, O. Capatina, A. Catinaccio, P. Ferracin, P. Grosclaude
CERN, Geneva, Switzerland

In recent years, optical fiber sensors have been increasingly used due to their outstanding performances. Their application is preferable in case of special requirements that exclude the application of conventional electrical sensors. The scientific background of optical fiber sensors is well developed. However, the characteristic of sensors employed in rather harsh environments is often different from the one determined in laboratory conditions or prior to their installation. In order to achieve long-term stable functioning and reliable measurement under severe working environments, such as those occurring at CERN (radiation, cryogenics, high magnetic and electrical field), a statistical measurement campaign was carried out following the international standard ISO 5725. The paper describes the ongoing study to define the accuracy of optical fiber sensors based on Fiber Bragg Grating (FBG) for strain measurements, from room temperature down to 4.2 K. It also describes some of the demanding applications for which optical fiber sensors have been deployed to perform experimental strain measurements (e.g. detectors components, high-energy beam targets and dumps, superconducting magnets).

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WEPMF084

Design, Prototyping Activities and Beam Irradiation Test for the New n_TOF Neutron Spallation Target

target, interface, neutron, proton

2582

R. Esposito, M. Bergeret, J. Busom, M.E.J. Butcher, M. Calviani, R. Cimmino, T. Coiffet, J.P.C. Espadanal, L. Gentini, R. Illan Fiastre, V. Maire, F. Ogallar Ruiz, A. Perillo-Marcone, S. Sgobba, M.A. Timmins, C. Torregrosa, E. Urrutia, V. Vlachoudis
CERN, Geneva, Switzerland
R. Logé
EPFL, Lausanne, Switzerland

A third-generation neutron spallation target for the neutron time-of-flight facility at CERN (n_TOF) is currently undergoing the design and prototyping stage. The new design aims at improving reliability, increasing beam intensity on target and avoiding issues encountered in the current generation target, in particular the contamination of the cooling system water with radioactive spallation products coming from washing out lead. After a preliminary design and an initial prototyping stage*, a baseline solution has been defined consisting in a pure lead target core contained in a Ti-6Al-4V cladding and embedded in a massive Pb block. A backup solution has also been defined, consisting in a Ta-cladded W core embedded in a Pb block. Both solutions are currently undergoing the detailed design stage. This contribution details the prototyping activity, the robustness studies for accidental scenarios and the design of a beam irradiation test on prototypes of the target core.
R. Esposito et al., "Design of the new CERN n_TOF neutron spallation target: R&D and prototyping activities," in Proc. of IPAC'17, Copenhagen, May 2017.

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WEPMG002

Beam Dump Facility Target: Design Status and Beam Tests in 2018

target, operation, experiment, simulation

2604

E. Lopez Sola, O. Aberle, P. Avigni, L. Bianchi, J. Busom, M. Calviani, M. Casolino, J.P.C. Espadanal, M.A. Fraser, S. Girod, B. Goddard, D. Grenier, M. Guinchard, C. Heßler, R. Illan Fiastre, R. Jacobsson, M. Lamont, A. Ortega Rolo, B. Riffaud, G. Romagnoli, L. Zuccalli
CERN, Geneva, Switzerland

The Beam Dump Facility (BDF) Project, currently in its design phase, is a proposed general-purpose fixed target facility at CERN, dedicated to the Search for Hidden Particles (SHiP) experiment in its initial phase. At the core of the installation resides the target/dump assembly, whose aim is to fully absorb the high intensity 400 GeV/c SPS beam and produce charmed mesons. In addition to high thermo-mechanical loads, the most challenging aspects of the proposed installation lie in very high energy and power density deposition that are reached during operation. In order to validate the design of the BDF target, a scaled prototype is going to be tested during 2018 in the North Area at CERN, upstream the existing beryllium primary targets. The prototype testing under representative beam scenarios will allow having an insight of the material response in an unprecedented regime. Online monitoring and an extensive Post Irradiation Experimental (PIE) campaign are foreseen. The current contribution will detail the design and handling aspects of the innovative Target Complex as well as the design of the BDF target/dump core and the design and construction of the prototype target assembly.

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WEPMG006

Experimental Setup to Characterize the Radiation Hardness of Cryogenic Bypass Diodes for the HL-LHC Inner Triplet Circuits

cryogenics, MMI, quadrupole, target

2620

A. Will, G. D'Angelo, R. Denz, M.F. Favre, D. Hagedorn, G. Kirby, T. Koettig, A. Monteuuis, F. Rodriguez-Mateos, A.P. Siemko, K. Stachon, M. Valette, A.P. Verweij, D. Wollmann
CERN, Geneva, Switzerland
A. Bernhard, A.-S. Müller
KIT, Karlsruhe, Germany
L. Kistrup
KEA, Copenhagen, Denmark

Funding: Work supported by the Wolfgang Gentner Programme of the German Federal Ministry of Education and Research
For the high luminosity upgrade of the Large Hadron Collider (LHC), it is planned to replace the existing triplet quadrupole magnets with Nb₃Sn quadrupole magnets, which provide a comparable integrated field gradient with a significantly increased aperture. These magnets will be powered through a novel superconducting link based on MgB₂ cables. One option for the powering layout of this triplet circuit is the use of cryogenic bypass diodes, where the diodes are located inside an extension to the magnet cryostat and operated in superfluid helium. Hence, they are exposed to radiation. For this reason the radiation hardness of existing LHC type bypass diodes and more radiation tolerant prototype diodes needs to be tested up to the radiation doses expected at their planned position during their lifetime. A first irradiation test is planned in CERN's CHARM facility starting in spring 2018. Therefore, a cryo-cooler based cryostat to irradiate and test LHC type diodes in-situ has been designed and constructed. This paper will describe the properties of the sample diodes, the experimental roadmap and the setup installed in CHARM. Finally, the first measurement results will be discussed.

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WEPML023

Design and Test Results of the 3.9 GHz Cavity for LCLS-II

cavity, cryomodule, operation, FEL

2730

N. Solyak, S. Aderhold, S.K. Chandrasekaran, C.J. Grimm, T.N. Khabiboulline, A. Lunin, O.V. Prokofiev, G. Wu
Fermilab, Batavia, Illinois, USA

The LCLS-II project uses sixteen 3.9 GHz superconduct-ing cavities to linearize energy distribution before the bunch compressor. To meet LCLS-II requirements origi-nal FNAL design used in FLASH and XFEL was signifi-cantly modified to improve performance and provide reliable operation up to 16 MV/m in cw regime [1-3]. Four prototype cavities were built and tested at vertical cryo-stat. After dressing, one cavity was assembled and tested at horizontal cryostat as part of design verification pro-gram. All auxiliaries (magnetic shielding, power and HOM couplers, tuner) were also re-designed and tested with this cavity. In this paper we will discuss cavity and coupler design and test results.

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WEPML055

Simulation Study of Parasitic-Mode Damping Methods for a 1.5-GHz TM020-Mode Harmonic Cavity

cavity, impedance, damping, coupling

2822

N. Yamamoto, S. Sakanaka, T. Takahashi
KEK, Ibaraki, Japan

Design study of parasitic-mode (PM) damped structures has been conducted for the purpose to realize a normal conducting 1.5 GHz harmonic cavity which is based on the TM020 resonant mode*. We have investigated the performances of two PM-damping mechanisms, that are, rod-type antennas** and annular slots. The rod-type antennas locate at the node of electric field of the TM020 mode while the annular slots locate at the node of magnetic field. As a result of 3D electromagnetic simulations, suitable performances of PMs were confirmed by employing either of the PM-damping mechanisms. It was also shown that the slot-type structure is superior in PM-damping performance and in the unloaded Q of the TM020 mode.
* N. Yamamoto et al., IPAC'17, paper THOPIK037; N. Yamamoto Phys. Rev. Accel. Beams, 21, 1, 012001.
** T. Takahashi et al., IPAC'17, paper THPIK036.

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THXGBE2

Optical Diagnostics for Extreme Beam Conditions

emittance, diagnostics, electron, experiment

2896

R.B. Fiorito
The University of Liverpool, Liverpool, United Kingdom

The development of simple, fast, precise and robust beam diagnostics is absolutely necessary to optimize the performance of present accelerators and to satisfy the needs of future accelerators, in particular those with ex-treme properties such as high brightness FELs and plasma wake-field accelerators. This invited talk will present the underlying physics and results from simulation and experiments for a number of advanced optical beam diagnostics currently under development at various accelerator re-search laboratories including efforts at the Cockcroft Institute.

Slides THXGBE2 [13.917 MB]

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THPAF012

The Influence of Chromaticity on Transverse Single-Bunch Instability in the Booster of HEPS

simulation, booster, damping, injection

2968

H.S. Xu, N. Wang
IHEP, Beijing, People's Republic of China

The study of the transverse single-bunch instability has been carried out for the HEPS booster to double check whether the required single-bunch charge can be achieved. The chromaticity has been varied in our study to see how the threshold changes accordingly. Usually, the slightly positive chromaticity is expected for stabilizing the beam. However, our simulations show that the single-bunch threshold current drops significantly when the chromaticity becomes non-zero. We present the simulation methods and results in details in this paper. The analysis of the simulation results is also presented.

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THPAK010

Optimization on the Optical Resonator of CTFEL

FEL, GUI, coupling, electron

3228

X.J. Shu, Y.H. Dou
Institute of Applied Physics and Computational Mathematics, People's Republic of China
M. Li, Z. Xu, Y. Xu, X. Yang
CAEP/IAE, Mianyang, Sichuan, People's Republic of China

Funding: Program for the National Science Foundation of China (Grant No. 11105019) and the National Science Device Exploitation Foundation of China (Grant No. 2011YQ130018).
A high power THz free electron laser (FEL) facility is under construction at China Academy of Engineering Physics (CTFEL) since October, 2011. The radiation frequency of the FEL facility will be tuned in range of 1~3 THz and the average output power is about 10 W. The system mainly consists of a GaAs photoemission DC gun, superconductor accelerator, the hybrid wiggler, optical cavity. The first lasing is obtained on Aug. 29, 2017. The optical resonator of CTFEL is optimized to ensure wavelength tunable in a wide range and high power operation. The FEL power strongly depends on the performance of the optical resonator including output efficiency, gain and round-trip loss. The optical resonator consists of metal-coated reflect mirror, the center-hole output mirror, waveguide. The influence of waveguide and Rayleigh length on the quality of optical cavity is evaluated by the 3D-OSIFEL code. The waveguide size, mirror curvature radius, output hole radius is optimized to different frequencies between 1 THz to 3 THz.

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THPAK025

Recent Developments in Beam Delivery Simulation - BDSIM

simulation, dipole, sextupole, interface

3266

L.J. Nevay, A. Abramov, S.T. Boogert, H. Garcia Morales, S.M. Gibson, W. Shields, S.D. Walker
JAI, Egham, Surrey, United Kingdom
J. Snuverink
PSI, Villigen PSI, Switzerland

Funding: Work supported by Science and Technology Research council grant 'The John Adams Institute for Accelerator Science' ST/P00203X/1 and Impact Acceleration Account.
Beam Delivery Simulation (BDSIM) is a program to seamlessly simulate the passage of particles in an accelerator, the surrounding environment and detectors. It uses a suite of high energy physics software including Geant4, CLHEP and ROOT to create a 3D model from an optical description of an accelerator and simulate the interaction of particles with matter as well as the production of secondaries. BDSIM is used to simulate energy deposition and charged particle backgrounds in a variety of accelerators worldwide. The latest developments are presented including low-energy tracking extension, more detailed geometry, support for ion beams and improved magnetic fields. A new analysis suite that allows scalable event by event analysis is described for advanced analysis such as the trace back of energy deposition to primary particle impacts.

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THPAK029

Studies of the Micro-Bunching Instability in the Presence of a Damping Wiggler

damping, wiggler, synchrotron, bunching

3273

M. Brosi, A. Bernhard, J. Gethmann, B. Kehrer, A.-S. Müller, A.I. Papash, P. Schreiber, P. Schönfeldt, J.L. Steinmann
KIT, Karlsruhe, Germany

Funding: Funded by BMBF (grant: 05K16VKA) & Helmholtz (contract: VH-NG-320). Supported by the Helmholtz International Research School for Teratronics & Karlsruhe School of Elementary and Astroparticle Physics.
At the KIT storage ring KARA (KArlsruhe Research Accelerator), the momentum compaction factor can be reduced leading to natural bunch lengths in the ps range. Due to the high degree of longitudinal compression the micro-bunching instability arises. During this longitudinal instability the bunches emit bursts of intense coherent synchrotron radiation in the THz frequency range caused by the complex longitudinal dynamics. The temporal pattern of the emitted bursts depends on given machine parameters, like momentum compaction factor, acceleration voltage, and damping time. In this paper the influence of the damping time is studied by utilizing the CLIC damping wiggler prototype installed in KARA as well as by simulations using the Vlasov-Fokker-Planck solver Inovesa.

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THPAK044

Self-Consistent Modeling using a Lienard-Wiechert Particle-Mesh Method

space-charge, simulation, synchrotron, emittance

3313

R.D. Ryne, C.E. Mitchell, J. Qiang
LBNL, Berkeley, California, USA
B.E. Carlsten
LANL, Los Alamos, New Mexico, USA

In this paper we describe a parallel, large-scale simulation capability using a Lienard-Wiechert Particle-Mesh (LWPM) method. The approach is a natural extension of the convolution-based technique to solve the Poisson equation in space-charge codes. It provides a unified method to compute both Coulomb-like self-fields and radiative phenomena like coherent synchrotron radiation (CSR). The approach brings together several mathematical and computational capabilities including the use of integrated Green function (IGF) methods and adaptive quadrature methods. We will describe the theoretical model and our progress to date.

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THPAK051

Computer Simulation of Explosive Emission Electrons Acceleration and X-ray Quantum Generation in Pulse Coaxial Diode System with Interior Anode

cathode, electron, simulation, target

3333

V.I. Rashchikov, A.A. Isaev, A.E. Shikanov, E.A. Shikanov
MEPhI, Moscow, Russia

Computer simulation of electrons from explosive emission acceleration and X-ray quantum generation in pulse coaxial diode system with interior anode, which is used in accelerating tube of compact X-ray generator* with Tesla transformer as high voltage source, was done. The results obtained allow us to choose accelerating tube diode system geometry for different running modes. Comparison of numerical results with experimental data of dose rate dependence on the distance from vacuum tube anode and energy at first circuit Tesla transformer was fulfilled.
*Patent RF N71817, 03.10.2007

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THPAK053

Side Effects of Local Bump in TPS Storage Ring

sextupole, quadrupole, storage-ring, dipole

3340

M.-S. Chiu, C.H. Chen, J.Y. Chen, P.J. Chou, F.H. Tseng
NSRRC, Hsinchu, Taiwan

The Taiwan Photon Source (TPS) is a low-emittance 3-GeV light source at National Synchrotron Radiation Research Center. Five in-vacuum undulator beamlines were delivered to users on Sep. 22, 2016. Another 2 EPU beamlines will be open to user in near future. In the beginning, the local bump was used to do ID spectrum optimization since 2016. After this procedure, the ID spectrum are consistent between theoretical simulation and measurement. Recently, we found the local bump will cause tune shift and orbit distortion. In this paper, we will present the effect of local bump in TPS.

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THPAK057

Simulations of Optical Stochastic Cooling with ELEGANT

damping, undulator, pick-up, kicker

3354

M.B. Andorf, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
V.A. Lebedev, V.A. Lebedev, P. Piot
Fermilab, Batavia, Illinois, USA

Fermilab is pursuing a proof-of-principle test of the Optical Stochastic Cooling (OSC) of 100 MeV electrons in the Integrable Optics Test Accelerator. In support of this we present simulations of horizontal damping with OSC. We find excellent agreement with theory on the amplitude dependent damping rates. Additionally particle tracking is used to confirm the necessity and effectiveness of sextupoles used to correct non-linear path lengthening in the OSC chicane.

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THPAK058

Planned Detection and Amplification of Infared Synchrotron Radiation for Electron-Beam Diagnostics and Manipulations

laser, experiment, synchrotron, synchrotron-radiation

3358

M.B. Andorf, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
P. Piot
Fermilab, Batavia, Illinois, USA

Amplification of beam-induced radiation (e.g. synchrotron or undulator radiation) is a necessary component of optical stochastic cooling of hadrons or heavy ions. We discuss a proposal to measure and amplify synchrotron radiation from a bending magnet of the Advanced Photon Source. The measurements will be in the short-wavelength infrared region (SWIR) and amplification will be accomplished using a pumped Chromium:Zinc Selenide (Cr:ZnSe) crystal with maximum gain at λ≅ 2.2~μm.

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THPAK064

Theoretical Modeling of Electromagnetic Field from Electron Bunches in Periodic Wire Medium

simulation, electron, lattice, FEL

3376

S.S. Chuchurka, A.I. Benediktovitch
BSU, Minsk, Belarus, Belarus
S.N. Galyamin, V.V. Vorobev
Saint Petersburg State University, Saint Petersburg, Russia
A. Halavanau
Northern Illinois University, DeKalb, Illinois, USA

Funding: Work supported by the Grant from Russian Foundation for Basic Research (No. 17-52-04107).
The interaction of relativistic electrons with periodic structures results in radiation by a number of mechanisms. In case of crystals one obtains parametric X-ray radiation, its frequency is determined by distance between crystallographic planes and direction of electron beam. If instead of crystal one considers a periodic structure of metallic wires with period of the order of mm, one can expect emission of THz radiation. In the present contribution we consider theoretical approaches for modeling of the distribution of electromagnetic field from electron bunches in lattice formed by metallic wires. The analytical description is possible for the case of wires with small radius, the range of validity is checked by numerical simulations. The intensity of radiation will be significantly increased if the electrons in the bunch could radiate coherently. Two possibilities will be discussed: the prebunching of the beam and the self-modulation of the beam due to interaction with radiated field.

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THPAK078

GPT-CSR: a New Simulation Code for CSR Effects

simulation, emittance, electromagnetic-fields, linac

3414

S.B. van der Geer, M.J. de Loos
Pulsar Physics, Eindhoven, The Netherlands
A.D. Brynes, P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
I.D. Setija, P.W. Smorenburg
ASML Netherlands B.V., Veldhoven, The Netherlands

For future applications of high-brightness electron beams, including the design of next generation FEL's, correct simulation of Coherent Synchrotron Radiation (CSR) is essential as it potentially degrades beam quality to unacceptable levels. However, the long interaction lengths compared to the bunch length, numerical cancellation, and difficult 3D retardation conditions make accurate simulation of CSR effects notoriously difficult. To ease the computational burden, CSR codes often make severe simplifications such as an ultra-relativistic bunch travelling on a prescribed reference trajectory. Here we report on a new CSR model implemented in the General Particle Tracer (GPT) code that avoids most of the usual assumptions: It directly evaluates the Liénard'Wiechert potentials based on the stored history of the beam. It makes no assumptions about reference trajectories, and also takes into account the transverse size of the beam. Example results demonstrating normalised emittance growth in the first bunch compressor of FERMI@Elettra are presented.

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THPAK121

Accelerator Optimization through LIV. DAT

plasma, proton, experiment, wakefield

3526

C.P. Welsch
The University of Liverpool, Liverpool, United Kingdom
C.P. Welsch
Cockcroft Institute, Warrington, Cheshire, United Kingdom

Funding: LIV. DAT is supported by the STFC under contract ST/P006752/1.
The Liverpool Big Data Science (LIV. DAT) Center for Doctoral Training (CDT) is a hub for training students in managing, analysing and interpreting large, complex datasets and high rates of data flow. LIV. DAT offers a unique training approach addressing some of the biggest challenges in data intensive science to tackle a growing skills gap. It currently provides training to a cohort of almost 20 PhD students. Their research projects address R&D challenges in astronomy, nuclear, particle and accelerator physics. This contributions presents initial research results from modeling studies of the physics and biology of proton beam therapy using a Monte Carlo approach, as well as plasma-beam interaction in the cases of AWAKE and EuPRAXIA.

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THPAK140

Pyroelectric Detection of Coherent Radiation on the CLARA Phase 1 Beamline

electron, dipole, detector, simulation

3577

B.S. Kyle
University of Manchester, Manchester, United Kingdom
R.B. Appleby, T.H. Pacey
UMAN, Manchester, United Kingdom
P.H. Williams
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
J. Wolfenden
The University of Liverpool, Liverpool, United Kingdom

The impacts of coherent synchrotron radiation (CSR) and space charge in the bunch compressor section of the CLARA Free Electron Laser (FEL) are expected to be significant, given the relatively high charge and short bunch lengths expected. The General Particle Tracer (GPT) code allows for the modelling of these effects in tandem, presenting an opportunity to more reliably estimate their effects on the CLARA beam. To provide confidence in future studies using GPT, a benchmarking study on the CLARA Phase 1 beamline is presented alongside relevant simulations. This study will make use of pyroelectric detectors to measure the emitted coherent power of the CLARA beam as it passes through a dispersive section whilst varying the chirp imparted on the bunches longitudinal phase space (LPS). Simulations presented demonstrate the viability of such a study, with energies between ∼ 10-100 nJ per pulse expected to be incident upon the detector face.

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THPAL043

Dipole Magnets for the Technological Electron Accelerators

dipole, electron, permanent-magnet, simulation

3739

I.S. Guk, O.M. Bovda, V.O. Bovda, A.N. Dovbnya, S.G. Kononenko, V.N. Ljashchenko, A. Mytsykov, L.V. Onishchenko, A.Y. Zelinsky
NSC/KIPT, Kharkov, Ukraine

Permanent magnets made of rare earth elements alloys allow to develop compact dipole magnets for the applied electron accelerator. These devices can be used for the beam trajectory bending as well as for the beam characteristics measurements. For NSC KIPT linear accelerator «EPOS» a dipole magnet on the base of Nd-Fe-B alloy has been designed and developed. The magnet provides 90 degrees bend of 23 MeV electron beam. The design value of magnetic field at the beam design trajectory is 0.5 Т. The magnet effective length is 242 mm. The magnet temperature can be changed with thermos-stabilization system. For NSC KIPT 10 MeV LU-10 applied accelerator a dipole magnet of Sm2Co17 alloy has been manufactured. The maximum magnet field of the magnet is 0.3 Т. The magnet layout allows easy magnet assembling at the accelerator chamber. The magnet is used for the beam energy measurement and accelerator beam energy turning. After energy turning the magnet should be removed from the accelerator lattice.

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THPAL044

The Permanent Magnets Magnetic Characteristics Change Under Effect of 10 MeV Beam

electron, experiment, permanent-magnet, ECR

3742

I.S. Guk, O.M. Bovda, V.O. Bovda, A.N. Dovbnya, A.I. Kalinichenko, S.S. Kandybey, V.N. Ljashchenko, A. Mytsykov, L.V. Onishchenko, O.A. Repikhov, A.Y. Zelinsky
NSC/KIPT, Kharkov, Ukraine

Magnets of applied electron accelerators are under direct effect of electrons and bremsstrahlung radiation stipulated by the electron beam. The choice of the materials for the rare elements alloy accelerator magnets has the decisive importance for the long term magnet parameters keeping. The experimental studies of the magnetic fields around the Nd-Fe-B and Sm2Co17 alloy magnets under effect of the electron beam have been done. The samples of 30х24х12 mm geometrical sizes were bombarded by electron beam of applied NSC KIPT accelerator KUT-1 with electron energy of 10 MeV and were irradiated by correspondent bremsstrahlung. The magnetic field value around Nd-Fe-B alloy samples was decreased nonlineary under electron beam bombarding with change of irradiation doze from 16 to 160 GRad. Under effect of bremsstrahlung the magnetic field value around samples was not changed. The repeated sample magnetizations allowed to restore the initial magnetic field distribution around magnets. The magnetic field distribution around Sm2Co17 alloy samples was not changed under effect of the electron beam and bremsstrahlung within irradiation dozes mentioned above. The induced activity in the Nd-Fe-B and Sm2Co17 alloy samples was changed slightly during the experiments.

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THPAL056

Vibration Measurements in the TPS Vacuum System

vacuum, synchrotron, storage-ring, synchrotron-radiation

3772

Y.C. Yang, C.K. Chan, C.-C. Chang, C.S. Chen, J. -Y. Chuang, Y.M. Hsiao, C.C. Liang, Y.Z. Lin
NSRRC, Hsinchu, Taiwan

The Taiwan Photon Source (TPS) is currently operated in top-up mode for users. In order to improve the stability of the synchrotron light source, vibrations related to the vacuum system have been investigated and improved by turning off pumping systems and reducing the flow rate in chamber cooling water circuits. In this paper, vibrations in different vacuum chambers with normal cooling water condition were investigated, their sources were recorded and clarified and properties of different materials for water tubes were also compared.

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THPAL058

Effect of Ozonated Water Cleaning on Photon Stimulated Desorption in a Stainless Steel Chamber

photon, vacuum, ECR, experiment

3778

C.M. Cheng, C.K. Chan, C.-C. Chang, Y.T. Cheng, J. -Y. Chuang, G.-Y. Hsiung, L.H. Wu, Y.C. Yang
NSRRC, Hsinchu, Taiwan

Aluminium vacuum chambers cleaned with ozonated water show a reduction of residual carbon and lower surface outgassing rate after baking. We would like to investigate if stainless steel chambers show similar ef-fects. A stainless steel test chamber was cleaned by stand-ard chemical cleaning only and then compared with an-other one after immersion in 30ppm ozonated water for thirty minutes. Both samples were baked, then photon exposed and the photon desorption yields were deter-mined by vacuum gauges and residual gas analysers at the TLS 19B beamline. The test results on photon stimulated desorption yields and partial pressure variations with and without ozonated water cleaning of the stainless steel tubes will be discussed in some detail.

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THPAL137

Acceptance Testing of the First Group of LCLS II Cryomodules at Jefferson Lab

cavity, cryomodule, operation, HOM

3965

M.A. Drury, E. Daly, N.A. Huque, L.K. King, M.D. McCaughan, A.D. Solopova
JLab, Newport News, Virginia, USA
J. Nelson
SLAC, Menlo Park, California, USA

Funding: This work was supported by the LCLS-II Project and the US Department of Energy, Contract DE-AC02-76SF00515.
The Thomas Jefferson National Accelerator Facility is currently engaged, along with several other Department of Energy (DOE) national laboratories, The Thomas Jefferson National Accelerator Facility is currently engaged, along with several other Department of Energy (DOE) national laboratories, in the Linac Co-herent Light Source II project (LCLS II). The SRF Insti-tute at Jefferson Lab is currently building 17 cryomod-ules for this project. The cryomodules are TESLA style cryomodules that have been modified for continuous wave (CW) operation and for other LCLS II specifica-tions. Each cryomodule contains eight 9-cell cavities with coaxial power couplers operating at 1.3 GHz. The cryomodules also contains a magnet package that con-sists of a quadrupole and two correctors. These cryomod-ules will be tested in the Cryomodule Test Facility (CMTF) at Jefferson Lab before shipment to the Stanford Linear Accelerator (SLAC). Acceptance testing of the LCLS II cryomodules began in December 2016. Seven cryomodules have currently completed Acceptance test-ing. This paper will summarize the results of those tests.

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THPAL158

Development of an Half-Cell Accelerating Structure in Tsinghua

cavity, simulation, GUI, alignment

4023

M.M. Peng, W. Gai, J. Shi, Z.H. Wang, H. Zha
TUB, Beijing, People's Republic of China

The half-cell high gradient accelerating structure is attractive for its easy manufacturing and good alignment. A structure with 12 cells has been designed for the frequency of 11.424 GHz and a cold test will be conducted. Two different mechanical factory manufacture with same machining drawing and the results will be compared.

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THPMF005

Evaluating the Impact of Diamond-II Possible Lattices on Beamlines

lattice, photon, synchrotron, emittance

4033

M. Apollonio, L. Alianelli, F. Bakkali Taheri, R. Bartolini, A.J. Dent
DLS, Oxfordshire, United Kingdom
R. Bartolini, J. Li
JAI, Oxford, United Kingdom

At Diamond Light Source we are considering an upgrade of the machine aimed at significantly reduced emittance (la factor 20), that follows a worldwide trend in similar synchrotron radiation sources. An important aspect in the design of the upgrade is the optimization of the photon beam properties, such as flux, brilliance, spot size, divergence or coherence of the new sources and how these are translated into requirements on the electron beam and on the machine design. We present a study based on a combination of accelerator physics tracking codes (AT, elegant) and of radiation codes (SPECTRA, SRW, SHADOW), with the aim at bridging the gap between machine and beamlines.

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THPMF014

First Experiments at the CLEAR User Facility

electron, experiment, operation, plasma

4066

R. Corsini, A. Curcio, S. Curt, S. Döbert, W. Farabolini, D. Gamba, R. Garcia Alia, T. Lefèvre, G. McMonagle, P.K. Skowroński, M. Tali, F. Tecker
CERN, Geneva, Switzerland
E. Adli, C.A. Lindstrøm, K.N. Sjobak
University of Oslo, Oslo, Norway
R.M. Jones, A. Lagzda
UMAN, Manchester, United Kingdom

The new "CERN Linear Electron Accelerator for Research" (CLEAR) facility at CERN started its operation in fall 2017. CLEAR results from the conversion of the CALIFES beam line of the former CLIC Test Facility (CTF3) into a new testbed for general accelerator R&D and component studies for existing and possible future accelerator applications. CLEAR can provide a stable and reliable electron beam from 60 to 220 MeV in single or multi bunch configuration at 1.5 GHz. The experimental program includes studies for high gradient acceleration methods, e.g. for CLIC X-band and plasma technology, prototyping and validation of accelerator components, e.g. for the HL-LHC upgrade, and irradiation test capabilities for characterization of electronic components and for medical applications. An overview of the facility capabilities and a summary of the latest results will be presented.

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THPMF016

Design of a Terahertz Radiation Source for Pump-Probe Experiments

bunching, undulator, electron, FEL

4073

J. Pfingstner, E. Adli
University of Oslo, Oslo, Norway
E. Marín
CERN, Geneva, Switzerland
S. Reiche
PSI, Villigen PSI, Switzerland

Narrow-band, tuneable, high-power terahertz radiation is highly demanded for pump-probe experiments at light source facilities. Since the requested radiation properties are not well covered by current terahertz radiation sources, an accelerator-based terahertz source employing the slotted-foil technique in combination with transverse deflecting cavities is proposed in this work. A detailed design has been worked out, and the behaviour of the electron beam and the created terahertz radiation is studied via numerical simulations. The results show that the proposed source produces tuneable terahertz radiation that can meet most of the demanded specifications.

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THPMF022

Study of Possible Beam Losses After Post-Linac Collimation at European XFEL

undulator, FEL, simulation, vacuum

4092

S. Liu, W. Decking
DESY, Hamburg, Germany
F. Wolff-Fabris
XFEL. EU, Schenefeld, Germany

The European XFEL has been operating with the undulator beam line SASE1 and SASE3 since April 2017 and February 2018, respectively. Despite of the fact that the post-linac collimation has collimated the beam halo to ~20 σ level*, relative high radiation doses have been measured especially in the diagnostic undulator (DU) section**. In order to find the sources of beam losses after post-linac collimation, BDSIM simulations have been performed. In this paper, we will first present the possible losses generated by the wire scanners upstream of the undulators during a scan. The simulation results will be compared with the measured doses along SASE1 and SASE3 undulators. Based on the simulation results, we will estimate the frequency for wire scanner opera-tions. Besides, the simulations with large extension of beam halo hitting the vacuum chamber aperture transition will also be presented. Finally, other possible radiation dose sources will be discussed.
* S. Liu et al., in Proc. of FEL 2017, Santa-Fe, USA, Aug. 2017, paper TUP003.
** F. Wolff-Fabris et al.,IPAC-2018 contribution.

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THPMF035

Numerical Analysis of Excitation Property of Pulse Picking by Resonant Excitation at BESSY II

betatron, synchrotron, kicker, emittance

4131

J.G. Hwang, M. Koopmans, R. Müller, M. Ries, A. Schälicke
HZB, Berlin, Germany

The pulse picking by resonant excitation (PPRE) method is applied at BESSY II to provide pseudo single bunch operation by separating the radiation from one horizontally enlarged bunch from the light of the multi-bunch filling. The bunch is enlarged by an excitation with an external signal close to the tune resonance. The variation of the beam size depends strongly on the frequency and amplitude of the excitation signal. In this paper we show the properties of the PPRE bunch studied by analytical modeling and numerical calculations using Elegant. The simulation results are compared with beam size measurements using a new interferometry beam size monitor at BESSY II.

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THPMF040

Experiences with the SRF Gun II for User Operation at the ELBE Radiation Source

gun, SRF, undulator, electron

4145

J. Teichert, A. Arnold, M. Bawatna, P.E. Evtushenko, M. Gensch, B.W. Green, S. Kovalev, U. Lehnert, P.N. Lu, P. Michel, P. Murcek, H. Vennekate, R. Xiang
HZDR, Dresden, Germany

Funding: The work is supported by the German Federal Ministry of Education and Research (BMBF) grant 05K12CR1.
The second version of the superconducting RF pho-toinjector (SRF Gun II) was successfully commissioned at the ELBE radiation source in 2014. The gun features an improved 3.5-cell niobium cavity combined with a super-conducting solenoid integrated in the cryostat. With a Mg photocathode the SRF Gun II is able to generate bunches with up to 200 pC and with sub-ps length in CW mode with 100 kHz pulse frequency for the THz radiation fa-cility at ELBE. In the ELBE linac, the beam is accelerat-ed, gets a proper correlated energy spread, and is com-pressed in a magnetic chicane. Sub-ps pulses are obtained producing coherent diffraction radiation and superradiant undulator radiation.

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THPMF057

Multi Colour X-Gamma Ray Inverse Compton Back-Scattering Source

laser, electron, photon, cavity

4196

I. Drebot, S. Cialdi, D. Giannotti, L. Serafini
Istituto Nazionale di Fisica Nucleare, Milano, Italy
R. Calandrino
HSP, Milan, Italy
P. Cardarelli, M. Gambaccini, G. Paternò, A. Taibi
INFN-Ferrara, Ferrara, Italy
G. Galzerano
Politecnico/Milano, Milano, Italy
V. Petrillo
Universita' degli Studi di Milano & INFN, Milano, Italy

We present a simple and new scheme for producing multi colour Thomson/Compton radiation with the possibility of controlling separately their polarization, based on the interaction of one single electron beam with two and more laser pulses that can come from the same laser setup or from two different lasers system and that collide with the electrons at different angle inside one optical cavity. One of the most interesting cases for medical applications is to provide two X-ray pulses across the iodine K-edge at 33.2 keV. The iodine is used as contrast medium in various imaging techniques and the availability of two spectral lines accross the K-edge allows one to produce subtraction images with a great increase in accuracy.

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THPMF058

The MariX source (Multidisciplinary Advanced Research Infrastructure with X-rays)

electron, FEL, cavity, gun

4199

V. Petrillo, N. Piovella
Universita' degli Studi di Milano, Milano, Italy
A. Bacci, F. Castelli, S. Cialdi, C. Curatolo, I. Drebot, D. Giannotti, D. Giove, C. Meroni, A.R. Rossi, L. Serafini, M. Statera, V. Torri
Istituto Nazionale di Fisica Nucleare, Milano, Italy
A. Bosotti, F. Broggi, F. Groppi, P. Michelato, L. Monaco, R. Paparella, D. Sertore
INFN/LASA, Segrate (MI), Italy
R. Calandrino, A. Delvecchio
HSP, Milan, Italy
F. Camera, S. Coelli, G. Onida, B. Paroli, L. Perini, F. Prelz, M. Rossetti Conti, F. Tomasi
Universita' degli Studi di Milano & INFN, Milano, Italy
P. Cardarelli, M. Gambaccini, G. Paternò, A. Taibi
INFN-Ferrara, Ferrara, Italy
A. Castoldi, G. Ghiringhelli, C. Guazzoni, M. Moretti, E. Pinotti
Polytechnic of Milan, Milano, Italy
S. Di Mitri
Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
A. Esposito, A. Gallo, C. Vaccarezza
INFN/LNF, Frascati (Roma), Italy
L. Faillace
RadiaBeam, Santa Monica, California, USA
G. Galzerano, E. Puppin, A. Tagliaferri
Politecnico/Milano, Milano, Italy
G. Mettivier, P. Russo
UniNa, Napoli, Italy
M. Placidi
LBNL, Berkeley, California, USA
G. Rossi
Università degli Studi di Milano, Milano, Italy
R.I. Saban
CERN, Geneva, Switzerland
A. Sarno
INFN-Napoli, Napoli, Italy
F. Stellato
INFN - Roma Tor Vergata, Roma, Italy
G. Turchetti
Bologna University, Bologna, Italy

MariX (Multidisciplinary advanced research infra-structure with X-rays) is a joint project of INFN and University of Milan, aiming at developing a twin X-ray Source of advanced characteristics for the future Sci-entific Campus of the University of Milan. Presently in its design study phase, it will be built in the post Expo area located in north-west Milan district. The first component of the X-source MariX is BriXS (Bright and compact X-ray Source), a Compton X-ray source based on superconducting cavities technology for the electron beam with energy recirculation and on a laser system in Fabry-Pérot cavity at a repetition rate of 100 MHz, producing 20-180 keV radiation for medical applications. The BriXS accelerator is also serving as injector of a 3.8 GeV superconductive linac, driving a X-ray FEL at 1 MHz, for providing coherent, moderate flux radiation at 0.3-10 KeV at 1 MHz. Scientific case, layout and typical parameters of MariX will be discussed.

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THPMF062

Smith-Purcell Radiation for Bunch Length Measurements at the Injection of MESA

detector, electron, operation, cavity

4213

P. Heil
IKP, Mainz, Germany
K. Aulenbacher
HIM, Mainz, Germany

Funding: Federal Ministry of Education and Research
MELBA is a test apparatus for the injector of the energy recovering, superconducting accelerator MESA in Mainz. A chopper-buncher system containing two circularly deflecting cavities and a first and second harmonic buncher cavity have been built. They serve to produce short bunches with a longitudinal extension < 600 μm (one degree of RF-phase) in the longitudinal focus for beam currents of up to 10mA. We intend to use Smith-Purcell Radiation (SPR) to test this arrangement. SPR is generated if a charged particle passes close to a periodic metallic structure, e.g. a grating. The signal has a coherent part which increases its intensity quadratically with the bunch charge if the bunch length is smaller than or comparable to the grating period. Different gratings can be placed below the electron beam to determine the length of the electron bunches. This measurement is non-destructive. The generated THz radiation will be observed with a bolometer cooled down to 4.2K which offers sufficient sensitivity in our regime of operation.

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THPMF069

Perturbation to Stored Beam by Pulse Sextupole Magnet and Disturbance of the Sextupole Magnetic Field in Aichi Synchrotron Radiation Center

synchrotron, synchrotron-radiation, injection, simulation

4232

A. Mochihashi
KIT, Eggenstein-Leopoldshafen, Germany
M. Fujimoto, M. Katoh
UVSOR, Okazaki, Japan
M. Hosaka, M. Hosaka, Y. Takashima, Y. Takashima, K. Y. Yamamura
Nagoya University, Nagoya, Japan
M. Hosaka, H. Ohkuma, Y. Takashima
Aichi Synchrotron Radiation Center, Aichi, Japan
M. Katoh
Sokendai - Okazaki, Okazaki, Aichi, Japan
H. Ohkuma
JASRI/SPring-8, Hyogo-ken, Japan

In the Aichi synchrotron radiation center (Aichi-SR), a pulse sextupole magnet (PSM) has been installed as a pulse magnet for beam injection. This leads to the injection scheme without using a bump orbit and stable supply of the synchrotron radiation. In Aichi-SR we have performed usual injection scheme with 4 kicker magnets and making the bump. Because the circumference of the Aichi-SR is only 72 m, 3 beam lines are inside the bump. The Aichi-SR has performed top-up operation since its public open, so it is a crucial subject to eliminate the disturbance of the synchrotron radiation during the injection. We have installed the PSM in 2015 and developed the beam study continuously. At present, however, a perturbation to the stored beam by the PSM still has been observed and is not acceptable. We have performed beam diagnostic experiment and concluded that an additional dipole kick affects the beam. From the magnetic field measurement data, we have discussed the source of the additional kick; most likely is an eddy current on the Ti coating inside the ceramics duct of the PSM. The beam diagnostics experiment and the magnetic field measurement will be discussed in the presentation.
Present affiliation of the first auther : Karlsruhe Institute of Technology

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THPMF074

Study of the Saturation of Radiation Energy Caused by the Space Charge Effect in a Compact THz Coherent Radiation Source

electron, undulator, simulation, laser

4245

S. Krainara, Chatani, S. Chatani, T. Kii, H. Ohgaki, H. Zen
Kyoto University, Kyoto, Japan

Funding: Institute of Advanced Energy, Kyoto University
To generate an intense quasi-monochromatic Terahertz Coherent Undulator Radiation (THz-CUR), a compact linac system, which employs a magnetic electron bunch compressor with a beam energy of 4.6 MeV, has been constructed at Kyoto University. The THz-CUR has suc-cessfully been generated in a frequency range from 0.16 to 0.65 THz with a bunch charge of 60 pC. The maximum micro-pulse energy of THz radiation was observed higher than 1 μJ at 0.16 THz with 160 pC. However, when a bunch charge was higher than 80 pC, the micro-pulse energy of THz radiation gradually went to the saturation and obviously at the bunch charge higher than 110 pC because of the bunch lengthening and degradation of electron beam quality due to the space charge effect. The dependence of a bunch length on a bunch charge has been studied by GPT simulation and compared with CTR and CUR experiments. The trends of the measured results from CUR and CTR are in good agreement with the GPT simulation.

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THPMF084

Numerical Shot Noise Modeling and Particle Migration Scheme

micro-particles, FEL, bunching, electron

4274

K. Hwang, J. Qiang
LBNL, Berkeley, California, USA

Funding: US Department of Energy under Contract no. DEAC02-05CH11231
In order to model correct statistical properties of shot noise, special particle loading algorithms were developed and used in FEL community. However, the compatibility of such loading algorithms with particle migration scheme across numerical mesh is not well studied. Here, we address the necessity of special particle migration scheme for different loading algorithms and present a possible solution pair.

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THPMK017

Experimental Study of Coherent THz Sources Driven by the NSRRC High Brightness Photo-injector

electron, undulator, linac, bunching

4332

M.C. Chou, K.T. Hsu, N.Y. Huang, J.-Y. Hwang, W.K. Lau, A.P. Lee, C.C. Liang, G.-H. Luo
NSRRC, Hsinchu, Taiwan

Accelerator-based coherent THz radiation sources are being studied with the NSRRC high brightness photoinjector which has been installed in the Accelerator Test Area (ATA) recently. This injector is equipped with a laser-driven photocathode rf gun and a 5.2-m long S-band traveling-wave linac for beam acceleration. A few tens MeV, ultrashort bunches of ~100 fs bunch length can be produced from the injector by velocity bunching technique. Tunable narrow-band THz coherent undulator radiation (CUR) can be generated from a U100 planar undulator when it is driven by such beam. One the other hand, broadband THz coherent transition radiation (CTR) generated by passing this beam through a metallic foil is used for determination of bunch length by autocorrelation technique. The experimental setup and results are presented in this paper.

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THPMK019

Generation of Tunable Femtosecond X-Rays from High-Period-Number Resonant Transition Radiation Emitters

electron, linac, photon, bunching

4339

P. Wang, K.C. Leou
NTHU, Hsinchu, Taiwan
M.C. Chou, J.-Y. Hwang, W.K. Lau, A.P. Lee
NSRRC, Hsinchu, Taiwan
C.T. Lee
ITRC, Hsinchu, Taiwan

Funding: Work supported by the Ministry of Science and Technology, ROC (Taiwan).
Femtosecond resonant transition radiation (RTR) in x-ray region can be generated from alternatively stacked multilayer structures when they are driven by relativistic ultrashort electron beams. These structures can be fabricated by coating layer pairs of high and low density materials. By increasing the number of these layer pairs, narrow-band x-ray can be generated. In this report, we present our efforts on the development of a 12 keV femtosecond narrow-band x-ray source by driving high-period-number RTR emitters with the NSRRC photoinjector linac system. Radiation wavelength is tunable by varying the incident angle of the beam. A few tens MeV, ultrashort beam has been available from the photoinjector system via velocity bunching in the rf linac. A 100-period (200 layers) Mo/Si multi-layer emitters with thin substrate have been fabricated. For a 100 pC drive beam, the expected photon yield from such emitter is about 4x104.

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THPMK022

Simulation for THz Coherent Undulator Radiation from Combination of Velocity Bunchings

bunching, electron, undulator, simulation

4345

Y. Sumitomo, K. Hayakawa, Y. Hayakawa, K. Nogami, T. Sakai, Y. Takahashi, T. Tanaka
LEBRA, Funabashi, Japan

We study the effect of a combination of velocity bunchings and its application to THz coherent undulator radiation at LEBRA, Nihon U. by simulations. The velocity bunching is a technique that is commonly used to make the bunch length shorter at lower energies. However, since one velocity bunching has a correlation between bunch energy and length, we may not have so much room to change energies to obtain different coherent radiation wavelengths. Hence we propose a combination of velocity bunchings, that relaxes the restrictive correlation. We have three 4m traveling-wave accelerator tubes at LEBRA, Nihon U. The undulator is installed after the acceleration tubes and 2 x 45 degree bending magnets. Since the design of current undulator requires less than 25 MeV beam energy to obtain the radiation at THz region, the velocity bunching is reasonable for coherent radiation. We show the simulation results of a combination of velocity bunchings of the three tubes and the magnetic bunching at bending magnets, suitable for the coherent undulator radiation.

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THPMK023

Coherent Transition Radiation Generated from Transverse Electron Density Modulation

electron, detector, simulation, experiment

4348

A. Halavanau, P. Piot
Northern Illinois University, DeKalb, Illinois, USA
A.I. Benediktovitch
BSU, Minsk, Belarus, Belarus
S.N. Galyamin, A.V. Tyukhtin
Saint Petersburg State University, Saint Petersburg, Russia
P. Piot
Fermilab, Batavia, Illinois, USA

Coherent Transition radiation (CTR) of a given frequency is commonly generated with longitudinal electron bunch trains. In this paper we present a study of CTR production from electron transverse density modulation. We demonstrate via numerical simulations a simple technique to generate THz-scale frequencies from mm-scale transversely separated electron beamlets. The results and a potential experimental setup are discussed.

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THPMK032

RADFET Installation at PAL-XFEL Undulator

undulator, FEL, controls, operation

4366

J.H. Han, Y.G. Jung, D.E. Kim, S.J. Lee, G. Mun
PAL, Pohang, Kyungbuk, Republic of Korea

Two undulator beamlines, one hard X-ray and one soft X-ray, are in operation at PAL-XFEL. Radiation produced during the FEL operation may impair the magnetic property of the undulator magnets and affect the FEL performance. Accumulated radiation at the undulator sections is being measured by using optically stimulated luminescent dosimeters (OSLDs) once per few months. Over 10 Gy gamma ray was detected at some locations at both undulator beamlines. However, in the measurement using the OSLDs we do not have information on which accelerator operation modes produce such high level of radiation on the undulators. To measure accumulated radiation in real time, we installed radiation-sensing field-effect transistors (RADFETs). We report the characteristics of the RADFET sensors and the installation at the PAL-XFEL undulator beamlines.

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THPMK034

Study on Effect of Phase Shifter on FEL Intensity at PAL-XFEL

FEL, undulator, electron, simulation

4372

C.H. Shim
POSTECH, Pohang, Kyungbuk, Republic of Korea
J.H. Hong, H. Yang
PAL, Pohang, Kyungbuk, Republic of Korea

In the PAL-XFEL, the phase shifters are installed be-tween the undulator modules to match the phase of the electron beam and the FEL radiation field at the entrance of next undulator. By varying the phase shifter gap, the FEL intensity measured at the QBPM oscillates and sine curve fitting can be applied to it for optimizing the FEL intensity. However, the optimal gap determined from fitting result is slightly different from the gap at which the maximum intensity is measured because distorted shapes are appeared from some phase shifters. In this presentation, we report and discuss the experimental results of phase shifter gap scanning with simulation results.

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THPMK035

Generation of Isolated Zeptosecond Pulse in Gamma-Ray Free Electron Laser

undulator, electron, ISOL, laser

4375

C.H. Shim, D.E. Kim
POSTECH, Pohang, Kyungbuk, Republic of Korea
Y.W. Parc
PAL, Pohang, Kyungbuk, Republic of Korea

An X-ray pulse with zeptosecond pulse duration is an essential tool to resolve the nuclear dynamics. To make such a short pulse duration, we need to make a very wide frequency range radiation which is known from the uncertainty principle. The spectral range of an isolated zeptosecond pulse has to be of order of few keV which is called as a gamma ray. In this presentation, the generation of an isolated zeptosecond pulses in the gamma-ray free electron laser is studied by the simulation.

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THPMK051

Theoretical Formulation of Improved SASE FEL Based on Slippage Enhancement Scheme

electron, FEL, undulator, laser

4398

C.-Y. Tsai, J. Wu, C. Yang, G. Zhou
SLAC, Menlo Park, California, USA
M. Yoon
POSTECH, Pohang, Kyungbuk, Republic of Korea
G. Zhou
IHEP, Beijing, People's Republic of China

Funding: The work was supported by the US Department of Energy (DOE) under contract DE- AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.
A method to improve the spectral brightness of self-amplified spontaneous emission (SASE) based on slippage enhancement has been proposed*, **. The implementation is to insert a series of magnetic chicanes to introduce a path-length delay of the electron beam to the radiation beam. By correlating the electron slices of neighboring cooperation distances this can lengthen the collective interaction and thus enhance the spectral brightness. In the existing literature most studies rely on numerical simulations and there is limited work on analytical analysis. In this paper we formulate the problem of slippage enhanced SASE (SeSASE) high-gain FEL with inclusion of by-pass magnetic chicanes. The analysis takes the finite energy spread of the electron beam and the nonzero momentum compaction of the chicane into consideration. The evolution of spectral bandwidth of SeSASE is compared with that of usual SASE in theory and numerical simulations. The effects of finite beam energy spread and non-isochronisity are also quantified.
*J. Wu et al., FEL2012
**B. W. J. McNeil et al., PRL 110, 134802 (2013)

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THPMK052

Numerical Simulation of Phase-Shift Method for Fel Power Enhancement in PAL-XFEL

undulator, electron, FEL, synchrotron

4402

C.-Y. Tsai, J. Wu, C. Yang, G. Zhou
SLAC, Menlo Park, California, USA
H.-S. Kang
PAL, Pohang, Kyungbuk, Republic of Korea
M. Yoon
POSTECH, Pohang, Kyungbuk, Republic of Korea
G. Zhou
IHEP, Beijing, People's Republic of China

Funding: The work was supported by the US Department of Energy (DOE) under contract DE- AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.
Recently the phase jump method for efficiency enhancement in free-electron laser (FEL) was proposed*. One of the unique features of PAL-XFEL with phase shifters may be taken for the experimental demonstration of this phase jump scheme. In this paper we numerically investigate the scheme using the three-dimensional numerical simulation code GENESIS**. The physical parameters are based on hard x-ray line of PAL-XFEL***. The preliminary simulation results indicate that this potential phase jump scheme can enhance at least one order of magnitude of FEL power performance. Combination of this scheme with undulator tapering is also discussed in this paper.
*A. Mak, F. Curbis, and S. Werin, PRAB 20, 060703 (2017)
**S. Rieche, NIMA 429(1):243-248 (1999)
***I. S. Ko et al., Appl. Sci. 2017, 7, 479 (2017)

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THPMK056

Effect of Transverse Radiation Defocusing in Post-Saturation Regime of High-Gain X-Ray Free-Electron Laser

electron, undulator, FEL, laser

4418

C.-Y. Tsai, J. Wu, C. Yang, G. Zhou
SLAC, Menlo Park, California, USA
M. Yoon
POSTECH, Pohang, Kyungbuk, Republic of Korea
G. Zhou
IHEP, Beijing, People's Republic of China

Funding: The work was supported by the US Department of Energy (DOE) under contract DE- AC02-76SF00515 and the US DOE Office of Science Early Career Research Program grant FWP-2013-SLAC-100164.
When untapered high-gain free electron laser (FEL) reaches saturation, the exponential growth ceases and the radiation power starts to oscillate about an equilibrium. For a high-gain tapered FEL, although the power is enhanced after the first saturation, it is known that there is a so-called second saturation point where the FEL power growth stops. In addition to the sideband instability, lack of transverse radiation focusing in the post-saturation regime can be another major reason leading to occurrence of the second saturation. In this paper we study the transverse diffraction effect and its impact on tapered FEL in the post-saturation regime. The study is carried out analytically together with three-dimensional numerical simulation. The numerical parameters are taken from LCLS-like electron beam and undulator system.

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THPMK070

Optimization for the Two-Stage Hard X-Ray Self-Seeding Scheme the SCLF

FEL, undulator, electron, simulation

4460

T. Liu, C. Feng, D. Wang, X. Wang, K.Q. Zhang
SINAP, Shanghai, People's Republic of China

Funding: Work supported by the National Natural Science Foundation of China 11475250 and 11605277, National Key Research and Development 2016YFA0401901 and Youth Innovation Promotion Association CAS 2015209.
Self-seeding mode has been demonstrated a great advantage for the achievement of a high brightness X-ray with a pure spectrum. Single-bunch self-seeding scheme with wake monochromators is adopted for the realization of the hard X-ray FEL at the Shanghai Coherent Light Facility (SCLF). Limited by the heat-loading of the monochromator, the two or multiple stages self-seeding scheme is required. In this contribution, we present a basic two-stage scheme design and optimization for the generation of the photon energy range of 3 keV to 15 keV at the line FEL-I of the SCLF. Simulation results show the peak power and pulse energy each stage, which illustrates the loaded energy required of the crystal monochromator as a pointcut of its following thermal analysis. The electron beam energy used in the study is 8 GeV and the central photon energy is 12.4 keV.

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THPMK075

A Possible Scheme for Generating High-harmonic Coherent Radiation in Storage Rings

electron, laser, bunching, storage-ring

4473

X.F. Wang, C. Feng, Z.T. Zhao
SINAP, Shanghai, People's Republic of China

A possible scheme for storage ring FEL which can introduce small energy dispersion and emittance simultaneously to generate intense coherent light in the storage rings is described. Based on a modiﬁed version of echo-enabled harmonic generation from free-electron lasers, the technique uses a dogleg and a wave-front tilted seed laser, one normal seed laser and two chicanes to make three-dimensional manipulation of the electron beam phase space, producing high-harmonic microbunching of a relativistic electron beam. Due to small energy dispersion and emittance growth, the storage rings do not need long damping time to recover the quality of the electron beams, so this scheme will significantly improve the performance of FELs based on rings. Theoretical analysis and numerical simulations demonstrate the capability of the proposed technique in Shanghai Synchrotron Radiation Facility.

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THPMK082

Micro Bunch Rotation and Coherent Undulator Radiation From a Kicked Beam

undulator, quadrupole, electron, focusing

4489

J.P. MacArthur
Stanford University, Stanford, California, USA
Z. Huang, J. Krzywinski, A.A. Lutman
SLAC, Menlo Park, California, USA

Recent observations of x-rays from a microbunched beam that has been kicked off-axis have shown coherent radiation at surprisingly large angles, in some cases reaching 30-50 uRad. Previous work on the topic has suggested that radiation at such large angles is inconsistent with classical radiation theory because microbunches cannot tilt. Here we show that, when kicked in a quadrupole lattice, microbunches can automatically tilt toward a new direction of propagation. This allows for coherent radiation farther off axis.

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THPMK083

Self-Modulation of a Relativistic Electron Beam in a Wiggler

electron, wiggler, laser, free-electron-laser

4492

J.P. MacArthur
Stanford University, Stanford, California, USA
J.P. Duris, Z. Huang, A. Marinelli, Z. Zhang
SLAC, Menlo Park, California, USA

Users at x-ray free-electron laser (FEL) facilities have shown strong interest in using single spike, coherent x-ray pulses to probe attosceond dynamics in atoms and molecules. Sub-femtosecond soft x-ray pulses may be obtained from an electron beam that has been modulated in a wiggler resonant with an external laser, the enhanced-SASE technique. We discuss a new way to produce this energy modulation, wherein the external laser is replaced by coherent radiation from the current spike on the tail of the electron beam. We calculate the modulation expected in a wiggler from both a single frequency perspective and a coherent synchrotron radiation (CSR) perspective.

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THPMK098

A Tunable Narrowband Source in the Sub-THz and THz Range at DELTA

laser, electron, detector, storage-ring

4534

C. Mai, B. Büsing, S. Khan, A. Meyer auf der Heide, B. Riemann, B. Sawadski, P. Ungelenk
DELTA, Dortmund, Germany
M. Brosi, J.L. Steinmann
KIT, Karlsruhe, Germany
F. Frei
PSI, Villigen PSI, Switzerland
C. Gerth
DESY, Hamburg, Germany
M. Laabs, N. Neumann
TU Dresden, Dresden, Germany
N.M. Lockmann
University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany

Funding: Work supported by the DFG (INST 212/236-1 FUGG), the BMBF (05K13PEC, 05K16PEB) and the state of NRW.
At DELTA, a 1.5-GeV electron storage ring operated as a synchrotron light source by the TU Dortmund University, an interaction of ultrashort laser pulses with electron bunches is used to generate broadband as well as tunable narrowband radiation in the frequency range between 75 GHz and 5.6 THz. The performance of the source was studied using two different Fourier-transform spectrometers. It was demonstrated that the source can be used for the characterization and comparison of Schottky-diode based detectors, e.g., an on-chip spectrometer enabling single-shot applications.

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THPMK099

Measurement of the Laser-Induced Energy Modulation Amplitude at the Short-Pulse Facility at DELTA

laser, electron, synchrotron, experiment

4538

A. Meyer auf der Heide, B. Büsing, S. Khan, N.M. Lockmann, C. Mai, B. Riemann, B. Sawadski
DELTA, Dortmund, Germany

The short-pulse facility at the synchrotron light source DELTA operated by the TU Dortmund University employs coherent harmonic generation (CHG) to provide ultrashort pulses in the vacuum ultraviolet and terahertz regime. Here, a laser-electron interaction results in a modulation of the electron energy which is transformed into a density modulation by a magnetic chicane. Measurements of the energy modulation amplitude with different techniques including an RF phase modulation are presented. A combination of the results allow to estimate the energy spread of the electron beam.

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THPMK112

An Updated Description of the FEL Simulation Code Puffin

undulator, electron, FEL, distributed

4579

L.T. Campbell, B.W.J. MᶜNeil, P.T. Traczykowski
USTRAT/SUPA, Glasgow, United Kingdom
L.T. Campbell
STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
B.W.J. MᶜNeil
Cockcroft Institute, Warrington, Cheshire, United Kingdom
J.D.A. Smith
TXUK, Warrington, United Kingdom

Puffin [1] is an unaveraged 3D FEL simulation tool with no Slowly Varying Envelope Approximation (SVEA), no undulator period averaging of the electron motion, and no periodic slicing of the electron beam, enabling simulation of broadband and high resolution FEL phenomena. It is a massively parallel code, written in modern Fortran and MPI, which scales from single core machines to HPC facilities. Its use in a number of projects since its initial description in 2012 has necessitated a number of additions to expand or improve its capability, including new numerical techniques, and the addition of a wide and flexible array of undulator tunings and polarizations along with electron beam optics elements for the undulator line. In the following paper, we provide an updated description of Puffin including an overview of these updates.
[1] L.T. Campbell and B.W.J. McNeil, Phys. Plasmas 19 093119 (2012)

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THPMK113

From Coherent Harmonic Generation to Steady State Microbunching

storage-ring, bunching, experiment, electron

4583

X.J. Deng, W.-H. Huang, T. Rui, C.-X. Tang
TUB, Beijing, People's Republic of China
A. Chao, D.F. Ratner
SLAC, Menlo Park, California, USA
J. Feikes, M. Ries
HZB, Berlin, Germany
R. Klein
PTB, Berlin, Germany

Steady state microbunching (SSMB) is an electron storage ring based scheme proposed by Ratner and Chao to generate high average power narrow band coherent radiation with wavelength ranging from THz to EUV. One key step towards opening up the potential of SSMB is the experimental proof of the SSMB principle. In this paper, the SSMB experiment planned and prepared by a recently established collaboration is presented starting from a modified coherent harmonic generation (CHG). Single particle dynamics of microbunching in an electron storage ring are analyzed. Though oriented for CHG and SSMB, some of the effects analyzed are also important in cases like bunch slicing, bunch compression, FEL beam transport lines etc, in which precise longitudinal phase space manipulations are involved. These dynamics together with some SSMB related collective effects are to be investigated on the storage ring MLS in Berlin.

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THPMK120

Hefei Advanced Light Source: A Future Soft X-Ray Diffraction-Limited Storage Ring at NSRL

storage-ring, lattice, emittance, injection

4598

L. Wang, Z.H. Bai, N. Hu, H.T. Li, W. Li, G. Liu, Y. Lu, Q. Luo, D.R. Xu, W. Xu, P.H. Yang, Z.H. Yang, S.C. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

To meet the fast-growing demands for high-quality low-energy photon beams, a new synchrotron radiation light source conception was brought forward several years ago by National Synchrotron Radiation Laboratory, which was named Hefei Advanced Light Source (HALS). The dominant radiation of HALS will be located in the VUV and soft X-ray region, which will be complementary with that of SSRF and HEPS. Except for high brilliance, high transverse coherence will be another signature feature of HALS. To achieve these goals, a multi-bend achromat based diffraction-limited storage ring was adopted as the main body of HALS. The general description and preliminary design of HALS will be briefly presented in this paper. Under the support of the Chinese Academy of Sciences and local government, the preliminary research and development (R&D) for HALS is undergoing. Several key technologies will be developed in the R&D project, which will lay good foundation for the construction of HALS.

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THPMK124

The Radiation Source for a Pre-Bunched THz Free Electron Laser

electron, undulator, FEL, laser

4608

R. Huang, Z.G. He, Q.K. Jia, H.T. Li, W.W. Li, Y. Lu, L. Wang, Z. Zhao
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Work is supported by National Natural Science Foundation of China (Grant No. 51627901)
Electron beam, generated in a photoinjector and bunched at terahertz (THz) frequency, will excite the coherent THz radiation when entering an undulator. We present a scheme of the radiation source for the pre-bunched THz free electron laser (FEL). The physical design of electron source is described in detail. The radiation frequency is widely tunable by both the pulse train tuning and the undulator gap tuning. It is simulation proved that the radiation power is greatly enhanced in our scheme.

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THPMK126

Numerical Method for Longitudinal Dynamics of a Terahertz Cherenkov Free Electron Laser Driven by a Mev Picosecond Electron Beam

electron, FEL, wakefield, GUI

4614

W.W. Li, Z.G. He, Q.K. Jia, S.M. Jiang, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China
D. He
Anhui Electrical Engineering Professional Technique College, Hefei, People's Republic of China

Funding: Natural Science Foundation of China (11705198, 11775216) China Postdoctoral Science Foundation (2017M622023) Fundamental Research Funds for the Central Universities (WK2310000061)
Corrugated or dielectric structures have been widely used for producing electron bunch train or THz radiation source. Recently, a novel scheme of sub-terahertz free electron laser (FEL) from a metallic pipe with corrugated walls driven by a non-ultra-relativistic (<10 MeV) picosecond electron beam was proposed and analyzed using the Vlasov-Maxwell equations. In this paper, we use the dielectric loaded waveguide instead, and a numerical method for the longitudinal beam dynamics and electromagnetics of the FEL interaction is presented.

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THPMK127

Terahertz Smith-Purcell Radiation From the High-Harmonic Component of Modulated Electron Beam From Dielectric Structure

electron, bunching, wakefield, simulation

4617

S.M. Jiang, Z.G. He, Q.K. Jia, W.W. Li, L. Wang
USTC/NSRL, Hefei, Anhui, People's Republic of China
D. He
Anhui Electrical Engineering Professional Technique College, Hefei, People's Republic of China

Funding: Supported by National Nature Science Foundation of China(11705198, 11775216)
In this paper, a new radiation scheme, which adopts the high order harmonic of modulated electron beam from dielectric loaded waveguide to excite the Smith-Purcell terahertz (THz) radiation, is proposed and in-vestigated by numerical simulations. The results show that the radiation with frequency close to 1.0 THz is generated, while, the fundamental bunching frequency of electron beam is 0.28 THz. Thus, this scheme offer a new method to get the higher frequency THz radiation.

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THPMK132

Generation of Terahertz Synchrotron Radiation Using Laser-Bunch Slicing at Hefei Light Source

laser, undulator, electron, synchrotron

4626

W. Xu, S.W. Wang, S.C. Zhang
USTC/NSRL, Hefei, Anhui, People's Republic of China

Hefei Light Source is a second-generation low-energy synchrotron light source. The low energy machine is ca- pable of generating intense Terahertz radiation through co- herent synchrotron radiation. To realize this, one method is to shorten the bunch length to the same level of its radi- ation wavelength, e.g. by adopting low-α lattice. Another method is to modulate the electron bunch to produce mi- costructure at picosecond scale and intense Terahertz co- herent synchrotron radiation can be obtained due to the in- crease ofthebunchformfactor. This techniqueis calledthe laser bunch slicing method which introduces a laser beam into an undulator to interact with the electron bunches. In this paper we report our work on the simulation of the laser bunch slicing at Hefei Light Source.

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THPMK138

Power Enhancement of Free-Electron Lasers Oscillators With the Natural Gradient of a Planar Undulators

FEL, undulator, simulation, electron

4632

Z. Zhao, L.J. Chen, Q.K. Jia, H.T. Li
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Work supported by National Natural Science Foundation of China (No. 21327901, 11205156)
Transverse Gradient Undulator (TGU) has been proposed with the initial purpose of mitigating the gain degradation in free electron laser (FEL) oscillators driven by beams with a large energy spread. However, a special-designed TGU with a fixed transverse gradient is required to enhance the gain. In this paper, we investigate using the natural field gradient of a normal planar undulator instead of a TGU to enhance the FEL oscillator (FELO) power. In this method, the beam is first vertically dispersed by a dogleg and then the dispersed beam passes through a normal undulator with a vertical off-axis orbit. Theoretical analysis and numerical simulation based on parameters of FELiChEM are presented. It demonstrates that this scheme can enhance the FEL power with careful optimization of dispersion strength and vertical beam orbit offset, especially when the energy spread is relatively large.

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THPMK144

Lattices for a 4th-Generation Synchrotron Light Source

lattice, synchrotron, emittance, SRF

4639

G. K. Shamuilov
Uppsala University, Uppsala, Sweden

Inspired by the ESRF upgrade (Extremely Brilliant Source, EBS), I present some modern lattices for a medium-sized 4th-generation synchrotron radiation source. They incorporate new elements, such as anti-bend magnets. The composed lattices are optimized using a simple double-objective algorithm. Its goal is to minimize the natural emittance and absolute chromaticities simultaneously. Then, the lattices are analyzed and compared to a version of the ESRF-EBS lattice scaled down in size. The design is performed to meet the needs of the user community of the Siberian Synchrotron and Terahertz Radiation Centre under the umbrella of the Budker Institute of Nuclear Physics.

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THPMK145

Evaluation of Coherent Terahertz Radiation Generated from Tilted Electron Beams Aiming for Higher Light Intensity

electron, target, controls, gun

4642

M. Brameld, K. Sakaue, Y. Tadenuma, M. Washio, R. Yanagisawa
Waseda University, Tokyo, Japan
R. Kuroda, Y. Taira
AIST, Tsukuba, Japan

Funding: This work was supported by a research granted from The Murata Science Foundation and JSPS KAKENHI 26286083.
When a target medium is irradiated by electron beams travelling at relativistic speed, terahertz(THz) radiation is produced by Cherenkov radiation. THz radiation is released at an angle to the direction of travel of the electron beams, and the coherence of the radiation can be improved by tilting the electron beams to match this angle, resulting in higher light intensity. The Cherenkov angle differs according to the refraction index of the target medium. At Waseda University, the generation of high-quality electron beams by a Cs-Te Photocathode RF-Gun and its applications are being researched. By utilizing the RF-Deflector, the tilt angle of the electron beam can be controlled to achieve coherent THz radiation. To gain higher light intensity, the use of Silicon and Aerogel as a target medium was challenged and compared to the conventional medium TOPAS. The THz radiation produced from the three target mediums were analyzed by use of the power meter and time domain spectroscopy(TDS). At this conference, the generation of THz Cherenkov radiation from different target mediums and the measurement results will be reported along with future perspectives.

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THPML022

Application of Surface Plasmon Polaritons on Charged particle Beam Diagnostics

electron, interface, vacuum, diagnostics

4699

Z.G. Jiang, D. Gu, Q. Gu, M.H. Zhao
SINAP, Shanghai, People's Republic of China

In Recent years, the Cherenkov light radiation transformed from surface plasmon polaritons has been found and proposed for a compact and adjustable light source. As the process is motivated by charged particle beam, the characteristics of the light are not only related with the device but can also reflect certain characteristics of the beam. In this paper, a beam position and energy measurement method has been proposed based on the Cherenkov light radiation transformed from surface plasmon polaritons. Early-stage numerical and analytical investigations are also presented for a planar structure device.

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THPML027

Longitudinal and Transverse Wakefields Simulations and Studies in Dielectric-Coated Circular Waveguides

electron, wakefield, GUI, simulation

4708

L. Ficcadenti
Rome University La Sapienza, Roma, Italy
A. Biagioni
INFN/LNF, Frascati (Roma), Italy
G. Castorina, D. Francescone, M. Marongiu, M. Migliorati, A. Mostacci, L. Palumbo
Sapienza University of Rome, Rome, Italy

In recent years, there has been a growing interest and rapid experimental progress on the use of e.m. fields produced by electron beams passing through dielectric-lined structures and on the effects they might have on the drive and witness bunches. Short ultra-relativistic electron bunches can excite very intense wakefields, which provide an efficient acceleration through the dielectric wakefield accelerators (DWA) scheme with higher gradient than that in the conventional RF LINAC. These beams can also generate high power narrow band THz coherent Cherenkov radiation. These high gradient fields may create strong instabilities on the beam itself causing issues in plasma acceleration experiments (PWFA), plasma lensing experiments and in recent beam diagnostic applications. In this work we report the results of the simulations and studies of the wakefields generated by electron beams at different lengths and charges passing on and off axis in dielectric-coated circular waveguides. We also propose a semi-analytical method to calculate these high gradient fields without resorting to time consuming simulations.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML027

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THPML042

Integrating the Lorentz Force Law for Highly-Relativistic Particle-in-Cell Simulations

plasma, laser, simulation, acceleration

4734

A.V. Higuera, J.R. Cary
Tech-X, Boulder, Colorado, USA
J.R. Cary
CIPS, Boulder, Colorado, USA

Funding: This work is supported by the DOE under Grants No. DE-SC0011617 and DE-SC0012444, and by DOE/NSF Grant No. DE-SC0012584
Integrating the Relativistic Lorentz Force Law for plasma simulations is an area of current research (*, **, ***). In particular, recent research indicates that interaction with highly-relativistic laser fields is particularly problematic for current integration techniques (****). Here is presented a special-purpose integrator yielding improved accuracy for highly-relativistic laser-particle interactions. This integrator has been implemented in the particle-in-cell code VSim, and the authors present an accuracy and performance comparison with several particle push methods.
* http://aip.scitation.org/doi/abs/10.1063/1.4979989
** https://arxiv.org/abs/1702.04486
*** https://arxiv.org/abs/1710.09164
**** http://aip.scitation.org/doi/abs/10.1063/1.4905523

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML042

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THPML063

Micro-Bunched Beam Production at FAST for Narrow Band THz Generation Using a Slit-Mask

electron, simulation, cavity, quadrupole

4784

J. Hyun
Sokendai, Ibaraki, Japan
D.J. Crawford, D.R. Edstrom, J. Ruan, J.K. Santucci, T. Sen, J.C.T. Thangaraj, R.M. Thurman-Keup
Fermilab, Batavia, Illinois, USA

We discuss simulations and experiments on creating micro-bunch beams for generating narrow band THz radiation at the Fermilab Accelerator Science and Technology (FAST) facility. The low-energy electron beamline at FAST consists of a photoinjector-based RF gun, two L-band superconducting accelerating cavities, a chicane, and a beam dump. The electron bunches are lengthened with cavity phases set off-crest for better longitudinal separation and then micro-bunched with a slit-mask installed in the chicane. We carried out the experiments with 30 MeV electron beams and detected signals of the micro-bunching using a skew quadrupole magnet in the chicane. In this paper, the details of micro-bunch beam production, the detection of micro-bunching and comparison with simulations are described.

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reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-THPML063

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THPML076

Design of Control System for Dual-Head Radiation Therapy

controls, linac, electron, Ethernet

4826

H.S. Kim, J.-S. Chai, M. Ghergherehchi, D.H. Ha, J.C. Lee, H. Namgoong, J.H. Seo, Shin, S.W. Shin
SKKU, Suwon, Republic of Korea
D. Lipka
DESY, Hamburg, Germany

Sungkyunkwan University groups have been developed advanced radiation therapy machine named dual-head radiation therapy gantry for reducing the treatment time by up to 30%. The main difference between previous radiation therapy machine is using two electron LINAC as X-ray sources at radiation therapy. In support of this system, control system based on SCADA and hardware development was implemented. The control system consists of supervisory computers and local controllers and the control network was ethernet and software was written by labVIEW. An overview of this control system is presented in paper.

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THPML098

Design of Beam Profile Monitor Used at the Xi'an Proton Application Facility (XiPAF)

detector, proton, experiment, synchrotron

4892

D. Wang, Z.M. Wang
State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Shannxi, People's Republic of China
W. Chen
NINT, Xi'an, People's Republic of China
P.F. Ma, Y.G. Yang
TUB, Beijing, People's Republic of China
W. Wang
Tsinghua University, Beijing, People's Republic of China

A pixel ionization chamber for beam profile monitor (BPrM) is designed and manufactured by a new technology .The detector will be installed on the beam line just upstream of the target device of XiPAF. It has many advantages such as high resolution, high radiation hardness and it can work as a real-time monitor to show the distribution of the delivered relative dose. The physics design and construction of the detector are described in this paper, and its performances are tested offline.

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THPML118

The AWAKE Electron Spectrometer

proton, electron, plasma, background

4947

F. Keeble, M. Cascella, J. A. Chappell, L.C. Deacon, S. Jolly, M. Wing
UCL, London, United Kingdom
I. Gorgisyan, S. Mazzoni
CERN, Geneva, Switzerland
P.L. Penna, M. Quattri
ESO, Garching bei Muenchen, Germany

The AWAKE experiment at CERN aims to use a proton driven plasma wakefield to accelerate electrons from 10–20 MeV up to GeV energies in a 10 m plasma cell. We present the design of the magnetic spectrometer which will measure the electron energy distribution. Results from the calibration of the spectrometer's scintillator and optical system are presented, along with a study of the backgrounds generated by the 400 GeV SPS proton beam.

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THPML140

Radiation Monitoring System of HLSII

monitoring, operation, detector, storage-ring

5011

Lin, H.S. Lin, Y.Q. Cai, S.P. Jiang, Z.B. Sun, Z.R. Zhou
USTC/NSRL, Hefei, Anhui, People's Republic of China

Funding: Supported by the National Science Foundation of China 11675170 By the Fundamental Research Funds for the Central Universities WK2310000056
Monitoring of ionizing radiation of synchrotron radiation facility is very important for the safety of staff and users of the light source. Radiation monitoring system of HLSII has been built and the whole system consists of local radiation monitoring spots and central control system, and a web-based monitoring dynamic release system. The local radiation monitoring spot consists of a high air pressure ionization type gamma detector and a BF3 counting tube neutron detector, and the radiation data are calculated by microcontroller locally and acquired by the data server for further processing. The dynamic release system is integrated with EPICS interface and radiation safety interlock system. Other accelerator systems could obtain radiation data from the server and the interlock system is triggered by the radiation data to shut down the machine in case the radiation exceeds the safety threshold.

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