SUSPSIK —  Special Student Poster Session   (14-May-17   14:00—18:00)
Chair: O. Boine-Frankenheim, GSI, Darmstadt, Germany
Paper Title Page
SUSPSIK001
 Impact of the Crossing Angle on Luminosity Asymmetries at the LHC in 2016 Proton Physics Operation  
TUPVA005   use link to access more material from this paper's primary paper code  
 
  • M. Hostettler
    LHEP, Bern, Switzerland
  • F. Antoniou, I. Efthymiopoulos, K. Fuchsberger, G. Iadarola, N. Karastathis, M. Lamont, Y. Papaphilippou, G. Papotti, J. Wenninger
    CERN, Geneva, Switzerland
  
  During 2016 proton physics operation at the CERN Large Hadron Collider (LHC), an asymmetry of up to 10% was observed between the luminosities measured by the ATLAS and CMS experiments. As the same bunch pairs collide in both experiments, a difference in luminosities must be of either geometric or instrumental origin. This paper quantifies the impact of the crossing angle on this asymmetry. As the beams cross in different planes in the two experiments, non-round beams are expected to yield an asymmetry due to the crossing angle. Results from crossing angle measurements at both experiments are also shown and the impact on the luminosities is evaluated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA005  
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SUSPSIK002
 Studies on Luminous Region, Pile-up and Performance for HL-LHC Scenarios  
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  • L.E. Medina Medrano, G. Arduini, R. Tomás
    CERN, Geneva, Switzerland
  • L.E. Medina Medrano
    UGTO, Leon, Mexico
  
  Funding: Research supported by the HL-LHC project and the Beam project (CONACYT, Mexico).
Studies on luminous region and pile-up density are of great interest for the experiments at the future High Luminosity LHC (HL-LHC) in order to optimize the detector performance. The evolution of these parameters at the two main interaction points of the HL-LHC along optimum physics fills is studied for the baseline and alternative operational scenarios with the latest set of parameters, including a refined description of the longitudinal bunch profile. Results are discussed in terms of a new figure-of-merit, the effective pile-up density. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK089  
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SUSPSIK003
 Macroparticle Simulation Studies of the LHC Beam Dynamics in the Presence of Electron Cloud  
TUPVA018   use link to access more material from this paper's primary paper code  
 
  • A. Romano, G. Iadarola, K.S.B. Li, G. Rumolo
    CERN, Geneva, Switzerland
  
  Beam quality degradation caused by the Electron Cloud (EC) effects has been identified as one of the main performance limitations for the high intensity 25 ns beams in the Large Hadron Collider (LHC). When a proton bunch passes through an EC, electrons are attracted towards the transverse center of the beam resulting into an increasing electron density within the bunch. The effects driven by the interaction of the electrons with the bunch have been studied with macroparticle simulations in order to evaluate, in different operational scenarios, the threshold for the coherent instabilities as well as the incoherent tune spread. This contribution will summarize the main findings of the simulation study and compare them with the available experimental observations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA018  
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SUSPSIK004
 CEPC Booster Lattice Design  
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  • T.J. Bian, X. Cui, J. Gao, C. Zhang
    IHEP, Beijing, People's Republic of China
  
  In September 2012, Chinese scientists proposed a Circular Electron Positron Collider(CEPC) at 240 GeV centre of mass for Higgs studies. The CEPC booster(CEPCB) provides 120 GeV electron and positron beams to the CEPC collider for top-up injection. We foucus on the beam dynamic study for CEPCB and analyse the key point of CEPCB lattice design. In this paper, a lattice design with good dynamic aperture is proposed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK022  
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SUSPSIK005
 High-Gradient Breakdown Studies of X-Band Choke-Mode Structures  
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  • X.W. Wu, H.B. Chen, J. Shi, H. Zha
    TUB, Beijing, People's Republic of China
  • T. Abe, T. Higo, S. Matsumoto
    KEK, Ibaraki, Japan
  
  As an alternative design for Compact Linear Collider (CLIC) main accelerating structures, X-band choke-mode damped structures had been studied for several years. However, the performance of choke-mode cavity under high power is still in lack of research. Two standing-wave single-cell choke-mode damped accelerating structures working at 11.424 GHz and one reference structure without choke were designed, manufactured, low-power measured, and tuned by accelerator group at Tsinghua University. High-power test had been done on them to study the breakdown phenomenon in high gradient and how the choke affects high-gradient properties. A max gradient of 75 MV/m were achieved by the choke-mode structure and the choke breakdown limited further increasing of the gradient. Inner surface inspection of the choke-mode structures indicates that the axial part of the choke limits the performance of the structure. Based on this observation, three new choke-mode structures were designed and being manufactured.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB010  
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SUSPSIK006
 Preliminary Design of FCC-ee Pre-Injector Complex  
TUPAB014   use link to access more material from this paper's primary paper code  
 
  • S. Ogur, Y. Papaphilippou, F. Zimmermann
    CERN, Geneva, Switzerland
  • A.M. Barnyakov, A.E. Levichev, D.A. Nikiforov
    BINP SB RAS, Novosibirsk, Russia
  • K. Furukawa, N. Iida, F. Miyahara, K. Oide
    KEK, Ibaraki, Japan
  
  The design of a 100 km circular e+e− collider with extremely high luminosity is an important component of the global Future Circular Collider (FCC) study hosted by CERN. FCC-ee is being designed to serve as Z, W, H and top factory, covering beam energies from 45.6 to 175 GeV. For the injectors, the Z-operation is the most challenging mode, due to the high total charge and low equilibrium emittance in the collider at this energy. Thus, fulfilling the Z-mode will also meet the demands for all other modes of FCC-ee. This goal can be achieved by using a 6 GeV NC linac with an S-band RF frequency of 2.856 GHz and a repetition rate of 100 Hz. This linac will accelerate two bunches per RF pulse, each with a charge of 6.5 nC. Positrons will be generated by sending 4.46 GeV e- onto a hybrid target so that the e+ created can still be accelerated to 1.54 GeV in the remaining part of the same linac. The emittance of the e+ beam will then shrink to the nm level in a 1.54 GeV damping ring. After damping, the e+ will be reinjected into the linac and accelerated to 6 GeV. The e- and e+ will then be accelerated alternately to 45.6 GeV in the booster, before they are injected into the collider.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB014  
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SUSPSIK007
 HTS-Coated Beam Screen for SPPC Bending Magnets  
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  • P.P. Gan, Q. Fu, H.P. Li, Y.R. Lu, K. Zhu
    PKU, Beijing, People's Republic of China
  • Y.D. Liu, J.Y. Tang, Q.J. Xu
    IHEP, Beijing, People's Republic of China
  
  For studying new physics beyond the Standard Model, Supper proton-proton Collider (SPPC) with a circumfer-ence of 100 km and a centre mass energy of 100 TeV is proposed and under study in China. Due to the high particle energies and 16 T high magnet field, the synchrotron radiation power emitted from the proton beams reaches 48.5 W/m in the bending magnets, two orders of magnitude higher than that of LHC. A novel beam screen is anticipated to screen cold chamber walls from the massive synchrotron radiation power and transfer the heat load to cryogenic cooling fluid. For drastically reducing resistive wall impedance and saving refrigerator power, we have studied high temperature superconductor (HTS) coated beam screen operating in liquid nitrogen temperature area. Singly from the point of temperature, the feasibility of HTS-coated beam screen is demonstrated by steady-state thermal analysis. Two kinds of potential HTS material are also discussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK024  
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SUSPSIK008
 Status of Crystal Collimation Studies at the LHC  
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  • R. Rossi, O. Aberle, O.Ø. Andreassen, M.E.J. Butcher, C.A. Dionisio Barreto, I. Lamas Garcia, A. Masi, D. Mirarchi, S. Montesano, S. Redaelli, A. Rijllart, W. Scandale, P. Serrano Galvez, G. Valentino
    CERN, Geneva, Switzerland
  • F. Galluccio
    INFN-Napoli, Napoli, Italy
  
  Crystal collimation is a technique that relies on highly pure bent crystals to coherently deflect beam particles - through the channeling mechanisms - onto dedicated absorbers. Standard multi-stage collimation systems for hadron beams use amorphous materials as primary collimators and might be limited by nuclear interactions and ion fragmentation that are strongly suppressed in crystals. A crystal collimation setup was installed in the betatron cleaning insertion of the Large Hadron Collider (LHC) to demonstrate with LHC beams the feasibility of this concept and to compare its performance with that of the present system. Channeling was observed for the first time with 6.5 TeV beam and and plans for further crystal collimation beam tests at the LHC are discussed. Results of these first beam tests are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB007  
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SUSPSIK009
 Study of the 2015 Top Energy LHC Collimation Quench Tests Through an Advanced Simulation Chain  
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  • E. Skordis, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • R. Bruce, F. Cerutti, A. Ferrari, P.D. Hermes, A. Lechner, A. Mereghetti, S. Redaelli, B. Salvachua, E. Skordis, V. Vlachoudis
    CERN, Geneva, Switzerland
  • C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  While the LHC has shown record-breaking perfor-mance during the 2016 run, our understanding of the behaviour of the machine must also reach new levels. The collimation system and especially the betatron cleaning insertion region (IR7), where most of the beam halo is intercepted to protect superconducting (SC) magnets from quenching, has so far met the expectations but could nonetheless pose a bottleneck for future operation at higher beam intensities for HL-LHC. A better under-standing of the collimation leakage to SC magnets is required in order to quantify potential limitations in terms of cleaning efficiency, ultimately optimising the collider capabilities. Particle tracking simulations com-bined with shower simulations represent a powerful tool for quantifying the power deposition in magnets next to the cleaning insertion. In this study, we benchmark the simulation models against beam loss monitor measure-ments from magnet quench tests (QT) with 6.5 TeV pro-ton and 6.37Z TeV Pb ion beams. In addition, we investi-gate the effect of possible imperfections on the collima-tion leakage and the power deposition in magnets.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB012  
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SUSPSIK010
 POP Experiment for the HB-HGHG Scheme at SXFEL  
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  • K.S. Zhou, H.X. Deng, C. Feng, D. Wang
    SINAP, Shanghai, People's Republic of China
  
  Abstract High brightness, fully coherent and ultra-short free electron lasers (FEL) operating in the soft x-ray region are opening up new frontiers in many scientific fields. In this paper, we perform the design studies for the proof-of-principle experiment of the recently proposed HB-HGHG scheme at SXFEL test facility with a two-stage setup. The first stage of SXFEL is used for the generation of the coherent signal at 30th harmonic of the seed through the coherent harmonic generation process. Then this coherent signal is shifted ahead by the 'fresh bunch' chicane of SXFEL and initiates the strong coherent radiation in the radiator of the second stage of SXFEL. The output properties have been compared with the conventional EEHG and the two-stage cascaded HGHG with the same harmonic up-conversion number.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB066  
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SUSPSIK011
 Study of ESASE Scheme with Microbunching Instability for Generating Attosecond-Terawatt X-Ray Pulse in XFELs  
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  • C.H. Shim, D.E. Kim, I.S. Ko
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • Y.W. Parc
    PAL, Pohang, Kyungbuk, Republic of Korea
  
  Recent studies show that the attosecond-terawatt X-ray pulse in XFELs can be generated by using ESASE (enhanced self-amplified spontaneous emission) scheme to obtain a sub-femtosecond spike in the electron peak current. However, ESASE scheme is not working properly when the microbunching instability is taken into account. The instability can be suppressed when the laser heater system which increases the uncorrelated energy spread of the electron beam is used in the injector. The effect of the microbunching instability on the performance of ESASE scheme will be discussed. In addition, the optimized results with the laser heater system for generating attosecond-terawatt X-ray pulse in XFELs is also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB070  
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SUSPSIK012
 On the Coherence Properties of FEL  
WEPAB074   use link to access more material from this paper's primary paper code  
 
  • M.A. Pop, F. Curbis, S. Werin
    MAX IV Laboratory, Lund University, Lund, Sweden
  
  Free Electron Lasers (FEL) are one of the most brilliant light sources in the world and their unique properties are driving worldwide research in understanding and improving them. Numerous papers have already been published describing the output of the FEL in terms of coherence and bandwidth. In this contribution, however, we focus on how the coherence evolves along the FEL undulator and on what factors influence it the most. Using Genesis−1.3* we have been able to follow and record the light field as it is being produced in the undulator. Our analysis method takes advantage of the extensively studied double pinhole experiment and uses the principles behind it to create a tool for extracting coherence information from the radiation field. We will present the scope, limitations and advantages of these virtual experiments as well as an application on an example FEL, to showcase what kind of information can be extracted using this method.
* Numerical simulation code used for particle and field distribution tracking along the undulator developed by Sven Reiche 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB074  
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SUSPSIK013
 Development of Injector System for MIR/THz Free-Electron Laser Facility in Thailand  
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  • W. Thongpakdi, S. Rimjaem
    Chiang Mai University, Chiang Mai, Thailand
  
  Development of a linac-based MIR/THz FEL light source is ongoing at the Plasma and Beam Physics Research Facility, Chiang Mai University. The future facility will consist of an S-band thermionic cathode RF electron gun, a pre-magnetic bunch compressor in a form of alpha magnet, an S-band travelling-wave linac structure, a 180-degree achromat system and two undulator magnets equipped with optical cavities. This research focuses on start-to-end beam dynamics simulations of the injector system. The aim of the study is to produce high quality electron beam at the entrance of the THz undulator magnet. The simulation was conducted by using programs PARMELA and ELEGANT. The program PARMELA was utilized to study the electron beam dynamics inside the RF-gun. Then, the program ELEGANT was used to optimize the injector system parameters. Optimization of physical specifications for the achromat system was performed to obtain short electron bunches with small energy spread at the undulator entrance. In this paper, results of beam dynamics simulations with suitable condition for the THz-FEL beamline are presented and discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB084  
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SUSPSIK014
 Dark Current Studies in the CLARA Front-End Injector  
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  • F. Jackson, I.R. Gesseypresenter, J.W. McKenzie, B.L. Militsyn, P.J. Tipping
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  At STFC Daresbury a new facility CLARA (Compact Linear Accelerator for Research and Applications) is being designed and constructed. The principal aim of CLARA is advanced Free Electron Laser research. Halo and dark current in CLARA is a concern for damage to the undulator, and other applications of the machine. Recently the front end (gun, diagnostics, first linac) of CLARA has been installed including some collimation to mitigate halo effects. Beam halo may arise from gun field emission or due to beam dynamics in the early stages of acceleration, which may achieve the same energy as the core beam and thus may be transported to the undulator. The code CST is used to study the gun field emission. The code ASTRA is used to study the transport of field emission through the front end, including the effectiveness of collimators. Machine measurements of dark current are compared against these simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB088  
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SUSPSIK015
 Design Study for the Generation of Few-Cycle FEL Pulses Using Mode-Locked Afterburner Scheme at Clara  
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  • C.L. Shurvinton, D.J. Dunning, N. Thompson
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  Ultrashort pulse operation in FELs is a highly desirable capability for imaging matter on ultrafast timescales. This paper presents a design study for a proof-­of-­principle demonstration of the mode-locked afterburner (ML-AB) scheme on the FEL test facility CLARA. A start-to-end simulation has been constructed using the time-­dependent three-­dimensional FEL code GENESIS 1.3 to evaluate the performance of the scheme. The ability to produce pulses of several femtoseconds in duration with peak powers of the order of 100 MW at 100 nm wavelength is predicted.­ Such pulses have duration of 2 fs (6 optical cycles), a factor of ~5 shorter than the FEL cooperation length. Potential routes for further optimisation and alternative operating modes are explored.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB089  
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SUSPSIK016
 Modelling Two-Colour FEL with Wide Wavelength Separation and Individual Polarisation Tuning  
WEPAB097   use link to access more material from this paper's primary paper code  
 
  • D. Bultrini, N. Thompson
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • R.J. Allan
    The Hartree Centre, Science and Technology Facilities Council (STFC/DL), Warrington, United Kingdom
  • L.T. Campbell, B.W.J. MᶜNeil
    USTRAT/SUPA, Glasgow, United Kingdom
  • D.J. Dunning, N. Thompson
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • J.D.A. Smith
    TXUK, Warrington, United Kingdom
  
  Free electron lasers (FELs) are currently enabling cutting edge research in chemistry, biology and physics. We use simulations to assess a new FEL capability that would add to the impressive repertoire of experiments made possible by the technology: a two-colour independent polarization mode, which allows for light pulses with variable temporal separation, individually tuneable polarisation, and widely separated wavelength. Simulations are carried out using the broad bandwidth FEL code Puffin, the results of which are used to discuss the radiation properties of the output. This scheme is applicable to existing and proposed facilities which feature undulators with variable ellipticity and gap.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB097  
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SUSPSIK017
 High Power Sub-Femtosecond X-Ray Pulse Study for the LCLS  
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  • J.P. MacArthur
    Stanford University, Stanford, California, USA
  • J.P. Duris, Z. Huang, A. Marinelli
    SLAC, Menlo Park, California, USA
  
  The desire to resolve sub-femtosecond electron dynamics has pushed FEL facilities to shorter pulse lengths. However, current short-pulse schemes provide low pulse energy and a gain-length limited lower bound on the pulse duration. The X-ray Laser-Enhanced Attosecond Pulses (XLEAP) project at SLAC is designed implement an Enhanced Self Amplified Spontaneous Emission (ESASE) scheme, which produces sub-fs current spikes by modulating and compressing the electron beam. We show through a series of Genesis simulations that the current spike is capable of producing sub-fs pulses with a peak power well above 100 GW. Space-charge induced beam chirp can decrease pulse lengths below 400 as, and multi-stage schemes can increase peak x-ray powers to around 1 TW.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB118  
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SUSPSIK019
 Coherent X-Ray Radiation From Electron Beam Processed by Channeling and Emittance Exchange  
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  • I. Lobach, A.I. Benediktovitch
    BSU, Minsk, Belarus
  
  Presented contribution theoretically studies a novel scheme of compact intense x-ray radiation source. In the scheme, longitudinally modulated electron beam emits x-rays by Inverse Compton Scattering (ICS). The setup's feature is the way how longitudinal density modulation in angstrom scale is created. There are three stages of processing of initial beam of relativistic electrons: 1. First, the electrons cross a crystal plate in channeling regime. It is shown that upon leaving the crystal, the electron beam acquires discernible transverse modulation in angstrom scale. It is taken into account that not all electrons are captured in channeling mode and that some of those that do may leave it as they travel through the crystal slab. 2. Further, the beam is transported to Emittance Exchange (EEX) line, in which the direction of modulation is tilted and the beam becomes longitudinally modulated. The scale of modulation remains the same. 3. Finally, intense quasi-coherent x-ray radiation is emitted by ICS. Numerical estimations show that coherent contribution to intensity is considerable for feasible parameters of used beam, components of EEX line and laser producing photons for ICS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA001  
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SUSPSIK020
 High Average Brilliance Compact Inverse Compton Light Source  
MOPVA036   use link to access more material from this paper's primary paper code  
 
  • K.E. Deitrick, J.R. Delayen, G.A. Krafft
    ODU, Norfolk, Virginia, USA
  • J.R. Delayen, G.A. Krafft
    JLab, Newport News, Virginia, USA
  
  Funding: Partially authored by Jefferson Science Associates, LLC under U.S. DOE contract NO. DE-AC05-6OR23177.
There exists an increasing demand for compact Inverse Compton Light Sources (ICLS) capable of producing substantial fluxes of narrow-band X-rays. While multiple design proposals have been made, compared to typical bremsstrahlung sources, most of these have comparable fluxes and improve on the brilliance within a 0.1% bandwidth by only a few orders of magnitude. By applying cw superconducting rf beam acceleration and rf focusing to produce a beam of small emittance and magnetic focusing to produce a small spot size on the order of a few microns at collision, the source presented here provides a 12 keV X-ray beam which outperforms other compact designs and bremsstrahlung sources. Compared to a bremsstrahlung source, the flux is improved by at least an order of magnitude and the average brilliance by six orders of magnitude. Surpassing other compact ICLS designs, the source presented here is attractive to a wide variety of potential users. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA036  
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SUSPSIK021
 The Study of Focus-Dependent Dark Current for AREAL RF Photogun  
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  • L. Hakobyan, H. Davtyan, B. Grigoryan, A. Vardanyan
    CANDLE SRI, Yerevan, Armenia
  
  AREAL (Advanced Research Electron Accelerator Laboratory) is a project of linear accelerator based facility aimed to produce ultra-short electron bunches with small emittance. In the first phase of AREAL project an electron beam with energy up to 5 MeV is produced by the electron RF photogun and used for irradiation experiments in biology, microelectronics and accelerator technology development. For such experiments the exact calculation of absorbed dose and electron bunch peak current is one of important conditions. The presence of a dark current in electron gun affects the electron emission from photocathode, the exact absorbed dose calculation, and in general harms the machine performance. In this paper the estimation of dark current amount, produced in the electron gun, the ways to avoid its influence on experiments are discussed. The dark current measurements are compared with the simulation results. The electron beam separation from a dark current is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB021  
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SUSPSIK022
 Study on CsKSb Photocathode for the RF Electron Gun  
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  • H. Ono, J. Miyamatsu, M. Washio
    Waseda University, Tokyo, Japan
  • H. Iijima
    Tokyo University of Science, Tokyo, Japan
  • K. Sakaue
    Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
  
  At Waseda University, we have been developing a Cs-Te photocathode S-band RF electron gun and application experiments of the electron beam. On the experiments, charge amount is important factor, which strongly depends on laser power and photocathode quality. At present, we are studying CsKSb photocathode to increase the charge amount of an electron beam generated from the RF-Gun. As a result of using CsKSb photocathode in the RF-cavity, we obtained as much charge as using Cs-Te photocathode but the lifetime was shorter than that of Cs-Te. In order to lengthen the photocathode lifetime, we tried to coat a protective film on CsKSb photocathode surface and investigated its robustness for poor vacuum condition that simulates cathode transportation and usage in the RF-Gun. In this conference, we report current status of fabricating coated photocathode and future prospects.
A. Buzulutskov et al. The protection of K-Cs-Sb photocathodes with CsBr films Nuclear Instruments and Methods in Physics Research A 400 (1997) 173-176 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB059  
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SUSPSIK023
 Progress of Pr2Fe14B Based Hybrid Cryogenic Undulators at SOLEIL  
TUOAA3   use link to access more material from this paper's primary paper code  
 
  • A.M. Ghaith, P. Berteaud, F. Blache, F. Briquez, N. Béchu, M.-E. Couprie, J. Da Silva Castro, J.M. Dubuisson, C. Herbeaux, C.A. Kitegi, A. Lestrade, O. Marcouillé, F. Marteau, M. Sebdaoui, G. Sharma, A. Somogyi, K.T. Tavakoli, M. Tilmont, M. Valléau
    SOLEIL, Gif-sur-Yvette, France
  • C. Benabderrahmane
    ESRF, Grenoble, France
  
  Cryogenic Permanent Magnet Undulators (CPMUs) take advantage of the enhanced field performance of permanent magnets when cooled down to low temperature, enabling shorter period with sufficient magnetic field to achieve high brightness radiation in the X-ray domain. Several CPMUs have been manufactured at SOLEIL. The first CPMU of period 18 mm (U18), optimized with a phase error of 3.2° at temperature of 77 K, has been installed and operated for the past 5 years at SOLEIL for the NANOSCOPIUM beamline. We report on photon beam based alignment enabling for a better adjustment of the vertical position offset of the undulator with a precision of 50 μm, and on the correction of the taper with a precision of 5 μrad to enhance the radiation flux. A second U18 cryo-ready undulator, with a new mechanical and magnetic sorting of module shimming, has attained a phase error of 2.3° at CT without any further adjustments after the assembly. Currently, two more CPMUs are being built; a 2 m long U18 for the SOLEIL ANATOMIX beamline, and a 3 m long U15 undulator reaching a magnetic gap of 3 mm. The new challenges encountered with magnetic measurements and mechanical designs for U15 are presented.  
slides icon Slides SUSPSIK023 [3.491 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUOAA3  
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SUSPSIK024
 Experimental Results on THz Superradiation From the Undulator in Tsinghua University Beamline  
TUPAB071   use link to access more material from this paper's primary paper code  
 
  • X.L. Su, Y.-C. Du, W.-H. Huang, L. Niu, C.-X. Tang, Q.L. Tian, D. Wang, L.X. Yan
    TUB, Beijing, People's Republic of China
  • Y.F. Liang
    Tsinghua University, Beijing, People's Republic of China
  
  In this paper, the first operation of a widely tunable 8-period undulator at terahertz (THz) frequency in Tsinghua University beamline was reported. Superradiate undulator radiation from sub-picosecond electron bunches compressed by chicane was observed. The measured radiation curve shows clearly that the radiation energy is proportional to the charge square, and the THz frequency can be changed from 0.4 THz to 10 THz with narrow-band spectrums. Our results demonstrate a high power and tunable coherent THz source, which could be useful for many applications in the future.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB071  
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SUSPSIK025
 Analysis of the Synchrotron Radiation from Segmented Undulator in Double-Mini Beta Function  
TUPIK106   use link to access more material from this paper's primary paper code  
 
  • H.W. Luo, C.H. Lee
    NTHU, Hsinchu, Taiwan
  • T.Y. Chung, C.-S. Hwang
    NSRRC, Hsinchu, Taiwan
  • C.-S. Hwang
    NCTU, Hsinchu, Taiwan
  
  Three long straight sections with double-mini beta-y lattice were created in the Taiwan Photon Source (TPS) for which the effects of focusing elements and phase shifters between the collinear undulators result in incorrect calculations of the brilliance while assuming a Gaussian-approximation. Therefore, an on-axis Wigner distribution function (WDF), which includes effects of wave phenomena, is a natural way to measure the intensity of synchrotron radiation and is used in this article as the definition of brilliance.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK106  
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SUSPSIK026
 Novel Implementation of Non-parametric Density Estimation in MICE  
WEPAB135   use link to access more material from this paper's primary paper code  
 
  • T.A. Mohayai
    IIT, Chicago, Illinois, USA
  • D.V. Neuffer, P. Snopok
    Fermilab, Batavia, Illinois, USA
  • C.T. Rogers
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • P. Snopok
    Illinois Institute of Technology, Chicago, Illlinois, USA
  
  Funding: Work supported by the U.S. Department of Energy under contract No. DE-AC05-06OR23100.
Cooled muon beams are essential to enable future Neutrino Factory and Muon Collider facilities. The international Muon Ionization Cooling Experiment (MICE) aims to demonstrate muon beam cooling through ionization energy loss in material. A figure of merit for muon cooling in MICE is the transverse root-mean-square (RMS) emittance reduction and to measure this, the individual muon positions and momenta are reconstructed using two scintillating-fiber tracking detectors housed in spectrometer solenoid modules. The reconstructed positions and momenta before and after a low-Z absorbing material are then used for constructing the covariance matrix and measuring normalized transverse RMS emittance of MICE muon beam. In this study, the direct measurement of phase-space density and volume as measures of the efficacy of muon beam cooling in MICE, using the density estimation techniques is described. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB135  
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SUSPSIK027
 Simulations of DLA Grating Structures in the Frequency Domain  
WEPVA002   use link to access more material from this paper's primary paper code  
 
  • T. Egenolf, O. Boine-Frankenheim, U. Niedermayer
    TEMF, TU Darmstadt, Darmstadt, Germany
  • O. Boine-Frankenheim
    GSI, Darmstadt, Germany
  
  Dielectric laser accelerators (DLA) driven by ultrashort laser pulses can reach orders of magnitude larger gradients than contemporary RF electron accelerators. A new implemented field solver based on the finite element method in the frequency domain allows the calculation of the structure constant, i.e. the ratio of energy gain to laser peak amplitude. We present the maximization of this ratio as a parameter study looking at a single grating period only. Based on this optimized shape the entire design of a beta-matched grating is completed in an iterative process. The period length of a beta-matched grating increases due to the increasing velocity of the electron when a subrelativistic beam is accelerated. The determination of the optimal length of each grating period thus requires the knowledge of the energy gain within all so far crossed periods. Furthermore, we outline to reverse the excitation in the presented solver for beam coupling impedance calculations and an estimation of the beam loading intensity limit.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA002  
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SUSPSIK028
 Laser Proton Accelerator with Improved Repeatability at Peking University  
WEPVA012   use link to access more material from this paper's primary paper code  
 
  • Y.R. Shou
    Peking University, School of Physics, Beijing, People's Republic of China
  • Y.X. Geng, C. Li, L.R.F. Li, Q. Liao, C. Lin, H.Y. Lu, W.J. Ma, P. Wang, M. Wu, X. Xu, X.Q. Yan, Y.Y. Zhao, J.G. Zhu
    PKU, Beijing, People's Republic of China
  
  Funding: National Basic Research Program of China (Grant No. 2013CBA01502), National Natural Science Foundation of China (Grants No. 11575011) and National Grand Instrument Project (2012YQ030142).
The repeatability of laser proton accelerator is mainly limited by laser plasma interaction, laser target coupling and laser parameter variation. In our recent experiments performed on the Compact Laser Plasma Accelerator at Peking University, gain of proton beams with improved repeatability is demonstrated. In order to control the laser plasma interaction in pre-plasma, cross polarized-wave (XPW) generation technique is employed to provide a laser pulse with a good contrast of 10-10. A semi-automatic laser and target alignment system with a sensitivity of few micrometers is employed. The repetition rate of the laser proton accelerator is improved to the level of 0.1 Hz which is beneficial to decrease laser parameter variation. The shot-to-shot variation of proton energies is about 9% for a level of confidence of 0.95. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA012  
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SUSPSIK029
 Structural Analysis and Evaluation of Actual PC Bridge Using 950 keV/3.95 MeV X-Band Linacs  
THPVA102   use link to access more material from this paper's primary paper code  
 
  • H. Takeuchi, R. Yano
    The University of Tokyo, Tokyo, Japan
  • K. Dobashi, Y. Mitsuya, M. Uesaka
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
  • M. Ishida, Y. Ohshima
    PWRI, Ibaraki, Japan
  • J. Kusano
    Accuthera Inc., Kawasaki, Kanagawa, Japan
  • I. Ozawa
    The University of Tokyo, The School of Engineering, Tokyo, Japan
  
  Funding: This work was supported by Council for Science, Technology and Innovation(CSTI), Cross-ministerial Strategic Innovation Promotion Program (SIP) (Funding agency: JST).
In Japan, bridges constructed in the highly economic growth era are facing to aging problem and advanced maintenance methods have been strongly required recently. To meet this demand, we develop the on-site inspection system using 950 keV/3.95 MeV X-band (9.3 GHz) linac X-ray sources*. These systems can visualize in seconds the inner states of bridge, including cracks of concrete, location and state of tendons (wires) and other imperfections. We focused on the inspection for wires which are critical to the safety of bridge. At the on-site inspections, the X-ray inspection system exhibited sufficient accuracy to detect the wire's corrosion. We also evaluated the maximum thickness of concrete to which our system can be applied. Using the 950 keV system, we conducted on-site inspection for real bridges and performed structural analysis to evaluate the bearing capacity of the bridge using finite element method. We plan to apply the 3.95 MeV linac for actual bridge inspection to extend the applicable range in 2017. For accurate visualization, the parallel motion CT technique for bridge inspection is in progress.
* Mitsuru Ueaska et al, On-site nondestructive inspection by upgraded portable 950keV/3.95MeV X-band linac x-ray sources, J. Phys. B: At. Mol. Opt. Phys. 47(2014) 234008 (9pp) 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA102  
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SUSPSIK030
 Efficiency Enhancement Induced by a Precursor Electron Bunch in Quasi-Phase Matched Direct Laser Acceleration  
WEPVA017   use link to access more material from this paper's primary paper code  
 
  • C.-Y. Hsieh, S.-H. Chen
    NCU, Chung Li, Taiwan
  • I. Jovanovic
    NERS-UM, Ann Arbor, Michigan, USA
  • M.W. Lin
    National Tsing-Hua University (NTHU), Hsinchu, Taiwan
  
  Funding: This work is supported by the Ministry of Science and Technology in Taiwan by Grant MOST 104-2112-M-008-013-MY3 and the United States Defense Threat Reduction Agency through contract HDTRA1-11-1-0009
Direct laser acceleration (DLA) of an electron bunch can be achieved by utilizing the axial field of a well-guided, radially polarized laser pulse in a density-modulated plasma waveguide*. However, the ponderomotive force of a TW-class laser pulse excites a plasma wave that can generate a defocusing electrostatic field, which significantly deteriorates the transverse properties of the injected electron witness bunch**. To improve the quality of the accelerated witness bunch, an additional leading electron bunch, termed as a precursor, is introduced to generate ion-focusing force to effectively confine the trailing witness bunch. We conducted three-dimensional particle-in-cell simulations to investigate the effect of bunch charge, transverse size of the precursor, and the axial separation between the precursor and the witness bunch on the efficacy of DLA. Results indicate that the transverse properties of the witness bunch can be maintained and the overall DLA efficiency can be improved, when a favorable ion-focusing force is provided by the precursor.
* A. G. York, et al., Phys. Rev. Lett. 100, 195001 (2008).
** M. -W. Lin et al., Phys. Plasmas 21, 093109 (2014). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA017  
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SUSPSIK031
 Group Velocity Matching in Dielectric-Lined Waveguides and its Role in Electron-THz Interaction  
WEPVA019   use link to access more material from this paper's primary paper code  
 
  • A.L. Healy, G. Burt
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • D.M. Graham
    The University of Manchester, The Photon Science Institute, Manchester, United Kingdom
  • S.P. Jamison
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  Terahertz(THz)-driven dielectric-lined waveguides have applications in electron manipulation, particularly acceleration, as the use of dielectric allows for phase velocities below the speed of light. However matching a single frequency to the correct velocity does not maximise electron-THz interaction; waveguide dispersion typically results in an unmatched group velocity and so the pulse envelope of a short THz pulse changes along the length of the structure. This reduces field amplitude and therefore accelerating gradient as the envelope propagates at a different velocity to the electron. Presented here is an analysis of the effect of waveguide dispersion on THz-electron interaction and its influence on structure dimensions and choice of THz pulse generation. This effect on net acceleration is demonstrated via an example of a structure excited by a single-cycle THz pulse, with a comparison of multi-cycle, lower intensity THz pulses on net acceleration.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA019  
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SUSPSIK032
 Phase Space Manipulation of Sub-Picosecond Electron Bunches Using Dielectric Wakefield Structures  
WEPVA021   use link to access more material from this paper's primary paper code  
 
  • T.H. Pacey, G.X. Xia
    UMAN, Manchester, United Kingdom
  • D.J. Dunning, Y.M. Saveliev
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  Dielectric lined waveguides have drawn interest due to their application as high gradient accelerating structures, in both externally driven and wakefield schemes. We present simulation studies of sub-picosecond electron bunches interacting with dielectric structures in the self-wake regime. The parameter space for a tunable, sub-millimeter aperture, terahertz frequency structure is investigated. The potential application as a longitudinal phase space dechirper is demonstrated, with specific application to CLARA at Daresbury Laboratory. The impact of transverse effects is considered and minimised. The resulting FEL output is simulated.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA021  
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SUSPSIK033
 Upgrade of the Two-Screen Measurement Setup in the AWAKE Experiment  
TUPIK001   use link to access more material from this paper's primary paper code  
 
  • M. Turner
    TUG/ITP, Graz, Austria
  • V. Clerc, I. Gorgisyan, E. Gschwendtner, S. Mazzoni, A.V. Petrenko
    CERN, Geneva, Switzerland
  
  The AWAKE project at CERN uses a self-modulated §I{400}{GeV/c} proton bunch to drive GV/m wakefields in a §I10{m} long plasma with an electron density of npe = 7 × 1014 \rm{electrons/cm}3. We present the upgrade of a proton beam diagnostic to indirectly prove that the bunch self-modulated by imaging defocused protons with two screens downstream the end of the plasma. The two-screen diagnostic has been installed, commissioned and tested in autumn 2016 and limitations were identified. We plan to install an upgraded diagnostics to overcome these limitations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK001  
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SUSPSIK034
 Electron Transport on COXINEL Beam Line  
TUPIK003   use link to access more material from this paper's primary paper code  
 
  • T. André, I.A. Andriyash, F. Blache, F. Bouvet, F. Briquez, M.-E. Couprie, Y. Dietrich, J.P. Duval, M. El Ajjouri, A.M. Ghaith, C. Herbeaux, N. Hubert, M. Khojoyan, M. Labat, N. Leclercq, A. Lestrade, A. Loulergue, O. Marcouillé, F. Marteau, P. N'gotta, P. Rommeluère, K.T. Tavakoli, M. Valléau
    SOLEIL, Gif-sur-Yvette, France
  • S. Bielawski, C. Evain, C. Szwaj
    PhLAM/CERLA, Villeneuve d'Ascq, France
  • S. Corde, J. Gautier, J.-P. Goddet, G. Lambert, B. Mahieu, V. Malka, S. Smartzev, C. Thaury
    LOA, Palaiseau, France
  • E. Roussel
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  
  COXINEL experiment aims at demonstrating free electron laser (FEL) amplification with a laser plasma accelerator (LPA). For COXINEL, a dedicated 8 m transport line has been designed and prepared at SOLEIL. We present here LPA beam transport results around 180 MeV through this line. Different electron beam optics were applied.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK003  
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SUSPSIK035
 External Injection Into a Laser-Driven Plasma Accelerator With Sub-Femtosecond Timing Jitter  
TUPIK009   use link to access more material from this paper's primary paper code  
 
  • A. Ferran Pousa, R.W. Aßmann, R. Brinkmann, A. Martinez de la Ossa
    DESY, Hamburg, Germany
  • A. Martinez de la Ossa
    University of Hamburg, Institut für Experimentalphysik, Hamburg, Germany
  
  The use of external injection in plasma acceleration is attractive due to the high control over the electron beam parameters, which can be tailored to meet the plasma requirements and therefore preserve its quality during acceleration. However, using this technique requires an extremely fine synchronization between the driver and witness beams. In this paper, we present a new scheme for external injection in a laser-driven plasma accelerator that would allow, for the first time, sub-femtosecond timing jitter between laser pulse and electron beam.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK009  
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SUSPSIK037
 Innovative Single-Shot Diagnostics for Electrons From Laser Wakefield Acceleration at FLAME  
TUPIK022   use link to access more material from this paper's primary paper code  
 
  • F.G. Bisesto, M.P. Anania, E. Chiadroni, A. Curcio, M. Ferrario, R. Pompili
    INFN/LNF, Frascati (Roma), Italy
  • A. Cianchi
    Università di Roma II Tor Vergata, Roma, Italy
  • A. Zigler
    The Hebrew University of Jerusalem, The Racah Institute of Physics, Jerusalem, Israel
  
  Plasma wakefield acceleration is the most promising acceleration technique known nowadays, able to provide very high accelerating fields (10-100 GV/m), enabling acceleration of electrons to GeV energy in few centimeters. Here we present all the plasma related activities currently underway at SPARC_LAB exploiting the high power laser FLAME. In particular, we will give an overview of the single shot diagnostics employed: Electro Optic Sampling (EOS) for temporal measurement and optical transition radiation (OTR) for an innovative one shot emittance measurements. In detail, the EOS technique has been employed to measure for the first time the longitudinal profile of electric field of fast electrons escaping from a solid target, driving the ions and protons acceleration, and to study the impact of using different target shapes. Moreover, a novel scheme for one shot emittance measurements based on OTR, developed and tested at SPARC_LAB LINAC, used in an experiment on electrons from laser wakefield acceleration still undergoing, will be shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK022  
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SUSPSIK038
 Gas-filled Capillaries for Plasma-Based Accelerators  
TUPIK023   use link to access more material from this paper's primary paper code  
 
  • F. Filippi
    INFN-Roma, Roma, Italy
  • M.P. Anania, A. Biagioni, E. Brentegani, E. Chiadroni, M. Ferrario, R. Pompili, S. Romeo
    INFN/LNF, Frascati (Roma), Italy
  • A. Cianchi
    INFN-Roma II, Roma, Italy
  • A. Zigler
    The Hebrew University of Jerusalem, The Racah Institute of Physics, Jerusalem, Israel
  
  Plasma Wakefield Accelerators are based on the excitation of large amplitude plasma waves excited by either a laser or a particle driver beam. The amplitude of the waves, as well as their spatial dimensions and the consequent accelerating gradient depend strongly on the background electron density along the path of the accelerated particles. The process needs stable and reliable plasma sources, whose density profile must be controlled and properly engineered to ensure the appropriate accelerating mechanism. Plasma confinement inside gas filled capillaries have been studied in the past since this technique allows to control the evolution of the plasma, ensuring a stable and repeatable plasma density distribution during the interaction with the drivers. Moreover, in a gas filled capillary plasma can be pre-ionized by a current discharge to avoid ionization losses. Different capillary geometries have been studied to allow the proper temporal and spatial evolution of the plasma along the acceleration length. Results of this analysis obtained by varying the length and the number of gas inlets will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK023  
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SUSPSIK040
 Driver-Witness-Bunches for Plasma-Wakefield Acceleration at the MAX IV Linear Accelerator  
TUPIK031   use link to access more material from this paper's primary paper code  
 
  • J. Björklund Svensson, H.E. Ekerfelt, O. Lundh
    Lund University, Lund, Sweden
  • J. Andersson, F. Curbis, M. Kotur, F. Lindau, E. Mansten, S. Thorin, S. Werin
    MAX IV Laboratory, Lund University, Lund, Sweden
  
  Beam-driven plasma-wakefield acceleration is an acceleration scheme promising accelerating fields of at least two to three orders of magnitude higher than in conventional radiofrequency accelerating structures. The scheme relies on using a charged particle bunch (driver) to drive a non-linear plasma wake, into which a second bunch (witness) can be injected at an appropriate distance behind the first, yielding a substantial energy gain of the witness bunch particles. This puts very special demands on the machine providing the particle beam. In this article, we use simulations to show that, if driver-witness-bunches can be generated in the photo-cathode electron gun, the MAX IV Linear Accelerator could be used for plasma-wakefield acceleration.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK031  
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SUSPSIK041
 Experimental Investigation of Field-Emission From Silicon Nano-Cone Cathodes  
MOPIK022   use link to access more material from this paper's primary paper code  
 
  • A. Lueangaramwong, C. Buzzard, V. Korampally, O. Mohsen, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • S. Chattopadhyay
    Northern Illinois Univerity, DeKalb, Illinois, USA
  • R. Divan
    Argonne National Laboratory, Argonne, Illinois, USA
  • P. Piot
    Fermilab, Batavia, Illinois, USA
  
  Funding: This work is supported by the NSF grant PHY-1535401 with Northern Illinois University
Field emission cathode are capable of forming electron beam with extreme brightness via strong-field excitation from applied electrostatic, or electromagnetic (radiofrequency and laser) fields. Our group, in collaboration with the Argonne Center for Nanoscale Material, has recently developed nanocone cathode. The present paper reports on the experimental characterization of these cathodes both configured as a single-cone emitter or as large arrays of tightly-packed emitter. The tests carried in a diode setup are capable of measuring IV characteristic curves and beam distributions. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK022  
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SUSPSIK042
 Investigation of a Splitring-RFQ for High Current Ion Beams at Low Frequencies  
TUPAB148   use link to access more material from this paper's primary paper code  
 
  • M. Baschke, H. Podlech, A. Schempp
    IAP, Frankfurt am Main, Germany
  
  For hadron linacs RFQs are the first stage of acceleration. To reach high intensities a new Splitring-RFQ is investigated. Not only a high current and high beam quality/brilliance should be achieved, also a good tuning flexibility and comfort for maintenance are part of the study. It will consist of two stages with 27 MHz and 54 MHz to accelerate ions with an A/q of 60 up to energies of 200 keV/u. Therefor RF simulations with CST MWS were done to study the quality factor and the shunt impedance as well as tuning possibilities. First results and the status of the project will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB148  
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SUSPSIK043
 The KONUS IH-DTL Proposal for the GSI UNILAC Poststripper Linac Replacement  
TUPVA067   use link to access more material from this paper's primary paper code  
 
  • H. Hähnel, U. Ratzinger, R. Tiede
    IAP, Frankfurt am Main, Germany
  
  Funding: BMBF 05P15RFRBA
The GSI UNILAC will serve as the main injector for the upcoming FAIR project. Since the existing Alvarez DTL is in operation for more than 40 years, it has to be replaced to ensure reliable operation in the future. To this purpose a compact and efficient linac design based on IH-type cavities and KONUS beam dynamics has been designed at IAP Frankfurt*. It consists of five 108 MHz IH-type cavities that can be operated by the existing UNILAC RF amplifier structure. The transversal focusing scheme is based on magnetic quadrupole triplet lenses. The optimized design provides full transmission and low emittance growth for the design current of 15 emA U28+ accelerating the beam from 1.4 MeV/u to 11.4 MeV/u. Extensive error studies were performed to define tolerances and verify the stability of the design with respect to misalignment and injection parameters. The design provides a compact and cost efficient alternative to a new Alvarez linac. With a total length of just 22.8 meters it will leave room for future energy upgrades in the UNILAC tunnel.
* H. Hähnel, U. Ratzinger, R. Tiede, Efficient Heavy Ion Acceleration with IH-Type Cavities for High Current Machines in the Energy Range up to 11.4 MeV/u, in Proc. LINAC2016, paper TUPLR070 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA067  
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SUSPSIK044
 Space charge effects of catch-up collision in a CW double-pass proton linac  
TUPVA140   use link to access more material from this paper's primary paper code  
 
  • Y. Tao, K. Hwang, J. Qiang
    LBNL, Berkeley, California, USA
  
  Recirculating superconducting proton linac has an advantage to reduce the number of cavities and the resulting accelerator construction/operation costs. Beam dynamics simulations were done recently in a double pass recirculating proton linac using a single bunch. For continuous wave (CW) operation, the high energy proton beam bunch during the second pass will catch up and collide with the low energy proton bunch at a number of locations inside the superconducting linac. In this paper, we report on the study of the space-charge effects during a collision on both beams through the rest of the linac.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPVA140  
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SUSPSIK046
 Design Study of Drift Tube Linac for BNCT Accelerator  
MOPAB099   use link to access more material from this paper's primary paper code  
 
  • Y. Lee, S.W. Jang, E.-S. Kim
    Korea University Sejong Campus, Sejong, Republic of Korea
  • B.H. Choi
    IBS, Daejeon, Republic of Korea
  • D.S. Kim
    Dawonsys, Siheung-City, Republic of Korea
  • Z. Li
    SCU, Chengdu, People's Republic of China
  
  A-BNCT accelerator is being developed as a proton accelerator with a high beam current of 50 mA for effective cancer therapy. Drift tube linac (DTL) with the length of 4.5 m is composed of 1 tank and 48 drift tubes (DTs). Proton beam is accelerated from 3 MeV to 10 MeV. Electromagnetic quadrupoles (EMQs) are inserted into every DT for transverse focusing. Slug tuners and post couplers (PCs) are used for accelerating field stabilization and resonant frequency tuning, respectively. The beam dynamics and engineering design for the DTL are performed for effective beam acceleration, and the design results are in detail presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB099  
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SUSPSIK047
 Tuning-Based Design Optimization of CLIC Final Focus System at 3 TeV  
MOPIK099   use link to access more material from this paper's primary paper code  
 
  • F. Plassard, A. Latina, E. Marín, D. Schulte, R. Tomás
    CERN, Geneva, Switzerland
  • P. Bambade
    LAL, Orsay, France
  
  The tuning aims to mitigate static imperfections of the Final Focus System (FFS) for emittance preservation at the Interaction Point (IP). A simulation campaign on the nominal CLIC FFS at 3 TeV have shown the need of rethink the design in order to ease the tuning of the machine. The goal is to optimize the lattice in order to make the FFS more tolerant to misalignments by reducing the strength of the sextupoles. The tuning efficiency is promoted as figure of merit to find the optimal layout of the FFS. A comparative study of the tuning performances have been performed for two L* options.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK099  
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SUSPSIK048
 Beam Dynamics in g-2 Storage Ring  
MOPIK119   use link to access more material from this paper's primary paper code  
 
  • W. Wu, B. Quinn
    UMiss, University, Mississippi, USA
  
  The muon anomalous magnetic moment has played an important role in constraining physics beyond the Standard Model. The Fermilab Muon g-2 Experiment has a goal to measure it to unprecedented precision: 0.14 ppm. To achieve this goal, we must understand the beam dynamics systematic effects in the muon storage ring. We will present the muon beam dynamics and discuss two specific topics here: the beam resonance which is related to the muon loss and the fast rotation analysis to determine the muon momentum distribution.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPIK119  
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SUSPSIK049
 BRho-Dependent Taylor Transfer Maps for Super-FRS Dipole Magnets  
WEPAB026   use link to access more material from this paper's primary paper code  
 
  • E.S. Kazantseva, O. Boine-Frankenheim
    TEMF, TU Darmstadt, Darmstadt, Germany
  • M. Berz, R. Jagasia, K. Makino
    MSU, East Lansing, Michigan, USA
  • H. Weick, J.S. Winfield
    GSI, Darmstadt, Germany
  
  The Super-FRS is an in-flight projectile fragment separator being built at GSI for FAIR. Due to the required high design momentum resolution and large acceptance (Ah= ±40mrad, Av= ±20mrad) the dipole magnets of the Super-FRS have large apertures (38×14cm²). The wide design magnetic rigidity (BRho) range 2-20 Tm requires the variation of the main dipole magnetic field B0 in the range 0.16-1.6 T. Since the upper third of the B0 range is situated in a non-linear saturation region of the magnetization curve B(H) and the spatial distribution of magnetic permeability in the steel yoke is non-uniform, the field distribution in the useful aperture of the magnet is a non-linear and non-uniform function of the excitation current I. One consequence is the shortening of the effective length and the change of the field distribution with increasing I. In this study we analyze these effects for the Super-FRS dipole magnets. We use 3D field distribution from FEM simulations for different I values and a resulting BRho(I). From the fields the Taylor transfer maps for the particles are obtained using DA techniques (COSY-infinity) and the convergence of the resulting transfer maps is discussed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPAB026  
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SUSPSIK050
 Preliminary Study of Beam Dynamics Compensation for the Elliptically Polarized Undulator at the HLS-II  
WEPIK080   use link to access more material from this paper's primary paper code  
 
  • Z.H. Yang, Z.H. Bai, W. Li, L. Wang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  An elliptically polarized undulator (EPU) was installed at the upgraded Hefei Light Source, HLS-II, for special users. Due to that the area of good field of the EPU is not large enough, the resulting beam dynamics is serious. At present, the lattice is changed to lower beta functions at the EPU to solve this problem. However, the compensation for the EPU is necessary for better operation of the machine in the future. In this paper, we used the surface fitting method to extract the Hamiltonian of the EPU from the real surface magnetic field data. Thus, we can obtain the effective Hamiltonian of the ring, which can be analyzed using normal form or other techniques. Then the beam dynamics effects resulting from the EPU can be compensated by optimizing the nonlinear quantities with striplines.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPIK080  
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SUSPSIK051
 Hénon-Heiles Single Particle Dynamics at IOTA  
WEOAB1   use link to access more material from this paper's primary paper code  
 
  • S. A. Antipov
    University of Chicago, Chicago, Illinois, USA
  • S. Nagaitsev
    Fermilab, Batavia, Illinois, USA
  
  A Hénon-Heiles system is a simple, classical nonlinear Hamiltonian system offering a wide range of particle dynamics from regular orbits to resonant behavior to chaotic trajectories. Initially proposed to describe the motion of stars around a galactic center, it remains a vivid topic in Dynamics and Mathematical Physics since its discovery in 1964. Although the system and its modifications have been extensively studied numerically, its dynamics has never been observed in a controlled experiment. In this report we show that it is possible to create the Hénon-Heiles Hamiltonian using sextupoles in a realistic accelerator lattice. We propose a special sextupole channel to create the desired potential at the IOTA ring and study the 3D single particle dynamics by frequency map analysis and Poincare cross-sections. The proposed experiment would allow real world testing of regular and chaotic motion with a controlled strength of the nonlinearity.  
slides icon Slides SUSPSIK051 [4.685 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEOAB1  
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SUSPSIK052
 Impedance Measurement of Vacuum Chamber Components for the Advance Photon Source (APS) Upgrade  
WEPVA134   use link to access more material from this paper's primary paper code  
 
  • M.P. Sangroula
    IIT, Chicago, Illinois, USA
  • R.M. Lill, R.R. Lindberg, X. Sun
    ANL, Argonne, Illinois, USA
  
  Funding: U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC0206CH11357.
The proposed Advance Photon Source Upgrade (APS-U) employs a multi-bend achromat (MBA) lattice to increase the photon brightness by two to three orders of magnitude. One of the main design challenges of the upgrade is to minimize rf heating and collective instabilities associated with the impedance of small-aperture vacuum components. As part of this effort, my research focuses on impedance measurement and simulation of various MBA vacuum components. Here, we present the summary of the impedance contributions for the APS-U and describe our planned impedance measurement technique, including some measurement results for the non-evaporative getter (NEG)-coated copper chamber and simulation results for other critical components using a novel Goubau line (G-line) set up. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA134  
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SUSPSIK053
 Microbunching Instability as a Caustic Phenomenon  
THPAB001   use link to access more material from this paper's primary paper code  
 
  • T.K. Charles, D.M. Paganin
    Monash University, Faculty of Science, Clayton, Victoria, Australia
  • M.J. Boland
    The University of Melbourne, Melbourne, Victoria, Australia
  • M.J. Boland, R.T. Dowd
    SLSA, Clayton, Australia
  
  Microbunching instability if left alone, threatens to degrade the beam quality of high brightness electron beams in Free Electron Lasers. Recently, caustic formation in electron trajectories was identified as a mechanism describing current modulations in accelerated particle beams. Here we consider CSR-induced microbunching as a caustic phenomenon. This analysis reports on the influence of longitudinal dispersion, R56, on the microbunching process, as well as elucidating the influence of the second and third order longitudinal dispersion values, T566 and U5666.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB001  
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SUSPSIK054
 Nuage, Ion Cloud Tracker  
THPAB006   use link to access more material from this paper's primary paper code  
 
  • A. Gamelin, C. Bruni, D. Radevych
    LAL, Orsay, France
  
  Funding: Work is supported by ANR-10-EQPX-51, by grants from Région Ile-de- France, IN2P3 and Pheniics Doctoral School.
NUAGE is a data parallel Matlab code which simulates the ion cloud effect in electron storage rings. The ion cloud is tracked in the ring taking into account the transverse and longitudinal effect of the beam-ion interaction, tracking in magnetic elements, usage of electrodes and gaps as clearing means. This program has been used to compute ionised ion equilibrium state and its neutralisation factor. In this article the NUAGE code is presented. The model, analysis method and performances are discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB006  
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SUSPSIK055
 Feasibility Analysis of Emittance Preservation During Bunch Compression in the Presence of Coherent Synchrotron Radiation in an Arc  
THPAB026   use link to access more material from this paper's primary paper code  
 
  • X.Y. Huang, X. Cui, S. Gu, Y. Jiao, G. Xu
    IHEP, Beijing, People's Republic of China
  
  Electron beam with low transverse emittance, short bunch length and high peak current is the basic requirement in modern high-brightness light sources. However, coherent synchrotron radiation (CSR) will dilute the transverse emittance when the electron beams pass through a magnetic bunch compressor and degrade the performance of the machine. In this paper, based on our CSR point-kick analysis, arc compressors with high compression factor in the presence of CSR effect are studied, both periodic and aperiodic arcs are included. Through analytical and numerical research, an easy optics design technique is introduced to minimize the emittance dilution within these compressors. Taking practical considerations into account, the results of periodic and aperiodic arcs are compared.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB026  
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SUSPSIK056
 Study of Beam Break Up in Irradiation Linacs  
THPAB031   use link to access more material from this paper's primary paper code  
 
  • X.C. Meng, H.B. Chen, W. Gai, J. Shi, S.X. Zheng
    TUB, Beijing, People's Republic of China
  • G.H. Li, J.S. Liu, Y.H. Liu
    NUCTECH, Beijing, People's Republic of China
  • F.H. de Sá
    LNLS, Campinas, Brazil
  
  Many recent experiments of the irradiation linacs produced at Tsinghua University indicate that beam power is limited by beam break up (BBU). Limits exist while the beam current or the pulse width is increased. In this paper, we illustrate the bream break up (BBU) phenomenon in the cases of both the 10MeV travelling-wave linac and 10MeV backward travelling-wave linac. The higher order modes in the linacs are analysed and the wake fields are calculated both with theoretical analysis and numerical simulation. Also, the beam dynamics is studied on the basis of the wakefield results to find a BBU threshold in these structures.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB031  
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SUSPSIK057
 Estimates of Collective Effects in the HALS Storage Ring Having the First Version Lattice  
THPAB032   use link to access more material from this paper's primary paper code  
 
  • N. Hu, Z.H. Bai, W. Li, Q. Luo, L. Wang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  The Hefei Advanced Light Source (HALS) is a diffraction-limited storage ring with a beam energy of 2.0 GeV. Recently the first version lattice has been designed for the HALS storage ring, and the natural emittance is about 18 pm·rad. In this paper, we study the collective effects in this storage ring, including calculations of intra-beam scattering effect and Touschek lifetime, and estimates of the thresholds of some single-bunch and multi-bunch instabilities.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB032  
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SUSPSIK058
 Studies of the Micro-Bunching Instability in Multi-Bunch Operation at the ANKA Storage Ring  
THOBA1   use link to access more material from this paper's primary paper code  
 
  • M. Brosi, E. Blomley, E. Bründermann, M. Caselle, B. Kehrer, A. Kopmann, A.-S. Müller, L. Rota, M. Schedler, M. Schuh, M. Schwarz, P. Schönfeldt, J.L. Steinmann, M. Weber
    KIT, Eggenstein-Leopoldshafen, Germany
  
  Funding: Supported by the German Federal Ministry of Education and Research (05K13VKA & 05K16VKA), the Helmholtz Association (VH-NG-320) and the Helmholtz International Research School for Teratronics (HIRST)
The test facility and synchrotron light source ANKA at the Karlsruhe Institute of Technology (KIT) operates in the energy range from 0.5 to 2.5 GeV and can generate brilliant coherent synchrotron radiation (CSR) in the THz range employing a dedicated bunch length-reducing optic at 1.3 GeV beam energy. The high degree of spatial compression leads to complex longitudinal dynamics and to time evolving sub-structures in the longitudinal phase space of the electron bunches. The results of the micro-bunching instability are time-dependent fluctuations and strong bursts in the radiated THz power. To study these fluctuations in the emitted THz radiation simultaneously for each individual bunch in a multi-bunch environment, fast THz detectors are combined with KAPTURE, the dedicated KArlsruhe Pulse Taking and Ultrafast Readout Electronics system, developed at KIT. In this contribution we present measurements conducted to study possible multi-bunch effects on the characteristic bursting behavior of the micro-bunch instability. 		 
slides icon Slides SUSPSIK058 [12.910 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THOBA1  
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SUSPSIK059
 Practical Stabilisation of Transverse Collective Instabilities with Second Order Chromaticity in the LHC  
THPVA026   use link to access more material from this paper's primary paper code  
 
  • M. Schenk, D. Amorim, N. Biancacci, X. Buffat, L.R. Carver, R. De Maria, K.S.B. Li, E. Métral, B. Salvant
    CERN, Geneva, Switzerland
  
  The study reports on dedicated measurements made with a single nominal bunch in the LHC at 6.5 TeV. First, we show that a significant amount of second order chromaticity Q'' can be introduced in the machine in a well-controlled manner. Second, we demonstrate that the incoherent betatron tune spread from Q'' can provide beam stability through the Landau damping mechanism. This is a first step in the development of a Q'' knob to be potentially applied during regular physics operation in the LHC.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA026  
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SUSPSIK060
 Studies of Longitudinal Beam Stability in CERN PS Booster After Upgrade  
THPVA023   use link to access more material from this paper's primary paper code  
 
  • D. Quartullo, S.C.P. Albright, E.N. Shaposhnikova
    CERN, Geneva, Switzerland
  
  The CERN PS Booster, comprised of four superposed rings, is the first synchrotron in the LHC proton injection chain. In 2021, after major upgrades, the injection and extraction beam energies, as well as the acceleration rate, will be increased. The required beam intensities should be a factor of two higher for nominal LHC and fixed-target beams, and the currently used narrow-band ferrite systems will be replaced by broad-band Finemet cavities in all four rings. Future beam stability was investigated using simulations with the Beam Longitudinal Dynamics (BLonD) code. The simulation results for existing situation were compared with beam measurements and gave a good agreement. An accurate impedance model, together with a careful estimation of the longitudinal space charge, was used in simulations of the future acceleration cycle in single and double RF, with phase and radial loops and controlled longitudinal emittance blow-up. Since the beam is not ultra-relativistic and fills the whole ring (h=1), the front and multi-turn back wakes were taken into account, as well as the RF feedbacks which reduce the effect of the Finemet impedance at the revolution frequency harmonics.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA023  
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SUSPSIK061
 Space-Charge Compensation in the Transition Area Between LEBT and RFQ  
THPVA006   use link to access more material from this paper's primary paper code  
 
  • P.P. Schneider, D. Born, V.A. Britten, M. Droba, O. Meusel, H. Podlech, A. Schempp
    IAP, Frankfurt am Main, Germany
  • D. Noll
    CERN, Geneva, Switzerland
  
  Funding: This work is supported by the German Federal Ministry of Education and Research (BMBF) #05P15RFRBA and by HORIZON 2020 for the MYRRHA project #662186
The transition from a space charge compensated beam in the LEBT to an uncompensated beam in the RFQ will influence the beam parameters. To investigate the impact of the electric fields on the space charge compensation, an insulated cone is used as a repeller electrode in front of the RFQ. Depending on the time dependent potential of the RFQ rods respectively to the beam potential, the compensation electrons may be prevented from moving into the RF field which oozes out of the RFQ entrance. The simulation studies are performed with the particle-in-cell code bender*. The simulations may substantiate measurements at the CW-operated RFQ in Frankfurt University** as well as at the foreseen MYRRHA LEBT-RFQ interface.*** In this contribution, a study on a LEBT-RFQ interface is shown. Results of numerical and experimental investigations will be compared.
*Noll, D. et al.The Particle-in-Cell Code Bender and Its Application to Non-Relativistic Beam Transport, WEO4LR02, HB'14
**Meusel, O. et al.FRANZ Accelerator Test Bench and Neutron Source.,MO3A03, LINAC'12
***R. Salemme et al.Design Progress of the MYRRHA Low Energy Beam Line, MOPP137, LINAC'14 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA006  
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SUSPSIK062
 The Influence of Initial Current Density Distribution on the Emittance Reduction  
THPAB023   use link to access more material from this paper's primary paper code  
 
  • H. Yamashita, T. Kii, K. Masuda, K. Nagasaki, T. Nogi, H. Ohgaki, K. Torgasin, H. Zen
    Kyoto University, Kyoto, Japan
  
  In this study, the influence of current density distribu-tion on the cathode surface on the beam emittance evolution was investigated. The emittance evolution with different beam profiles (flat-top, peak and hollow distribution) have been compared. The modification of the current profile was shown to affect the axial distance of the point of minimal emittance over wide range. The hollow profile allows extending the axial distance of the point of emittance minimum keeping its value extremely low. Further the parameters of a peak profile, which give the smallest emittance were determined. This work demonstrates the significance of initial current density distribution for the emittance evolution.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB023  
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SUSPSIK063
 Emittance Measurements and Simulations in 112 MHz Super-Conducting RF Electron Gun With CsK2Sb Photo-Cathode  
THPAB087   use link to access more material from this paper's primary paper code  
 
  • K. Mihara
    Stony Brook University, Stony Brook, USA
  • D. Kayran, V. Litvinenko, T.A. Miller, I. Pinayev
    BNL, Upton, Long Island, New York, USA
  
  The commissioning of the coherent electron cooling (CeC) proof of principle experiment is under way at Relativistic Heavy Ion Collider (RHIC).. A 112 MHz superconducting radio frequency photo-emission gun is used to generate the electron beam for this experiment. In this paper we report selected results of experimental emittance measurements and compare them with our simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB087  
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SUSPSIK064
 Comparison of Theory, Simulation, and Experiment for Dynamical Extinction of Relativistic Electron Beams Diffracted Through a Si Crystal Membrane  
THPAB088   use link to access more material from this paper's primary paper code  
 
  • L.E. Malin, W.S. Graves, J. Spence, C. Zhang
    Arizona State University, Tempe, USA
  • R.K. Li, C. Limborg, E.A. Nanni, X. Shen, S.P. Weathersby
    SLAC, Menlo Park, California, USA
  
  Diffraction in the transmission geometry through a single-crystal silicon slab is exploited to control the intensity of a relativistic electron beam. The choice of crystal thickness and incidence angle can extinguish or maximize the transmitted beam intensity via coherent multiple Bragg scattering; thus, the crystal acts as a dynamical beam stop through the Pendel'sung effect, a well-known phenomenon in X-ray and electron diffraction. In an initial experiment, we have measured the ability of this method to transmit or extinguish the primary beam and diffract into a single Bragg peak. Using lithographic etching of patterns in the crystal we intend to use this method to nanopattern an electron beam for production of coherent x-rays. We compare the experimental results with simulations using the multislice method to model the diffraction pattern from a perfect silicon crystal of uniform thickness, considering multiple scattering, crystallographic orientation, temperature effects, and partial coherence from the momentum spread of the beam. The simulations are compared to data collected at the ASTA UED facility at SLAC for a 340 nm thick Si(100) wafer with a beam energy of 2.35 MeV.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB088  
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SUSPSIK065
 Multi-Objective Optimization of an SRF Photoinjector for ERL and UED Applications  
THPAB009   use link to access more material from this paper's primary paper code  
 
  • E. Panofski, A. Jankowiak, T. Kamps, G. Kourkafas
    HZB, Berlin, Germany
  • S. Eisebitt
    MBI, Berlin, Germany
  
  Superconducting RF photoinjectors, running in continuous-wave (cw) mode, are able to generate electron beams of high average brightness and ultra-short bunches. Therefore, they satisfy the requirements of future accelerator facilities, such as energy recovery linacs (ERL). Further, SRF guns are able to provide relativistic probe beams for ultrafast electron diffraction (UED). Choosing suitable values for the drive laser, cavity and solenoid settings poses a great challenge for the injector commissioning and operation. Using multi-objective optimization based on an evolutionary algorithm, optimum gun parameter settings are extracted from Pareto-optimum solutions. The development of a universal multi-objective optimization algorithm for SRF photoinjectors as well as first Pareto optimum results for an ERL and UED application of GunLab, the compact SRF gun test facility at Helmholtz-Zentrum Berlin, will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB009  
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SUSPSIK066
 Symplectic Multi-Particle Tracking Using Cuda  
THPAB027   use link to access more material from this paper's primary paper code  
 
  • Zh.C. Liu
    IHEP, Beijing, People's Republic of China
  • J. Qiang
    LBNL, Berkeley, California, USA
  
  Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231 and the Ministry of Science and Technology of China under Grant No.2014CB845501.
The symplectic tracking model can preserve phase space structure and reduce non-physical effects in long term simulation. Though this model is computationally expensive, it is very suitable for parallelization and can be accelerated significantly by using Graphic Processing Units (GPUs). Using a single GPU, the code achieves a speedup of more than 400 compared with the time on a single CPU core. It also shows good scalability on a GPU cluster at Oak Ridge Leadership Computing Facility. In this paper, we report on the GPU code implement, the performance test on both single-GPU and multi-GPU cluster, and an application of beam dynamics simulation. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB027  
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SUSPSIK067
 Development of Computational Tools for Noise Studies in the LHC  
THPAB044   use link to access more material from this paper's primary paper code  
 
  • S. Kostoglou, N. Karastathis, Y. Papaphilippou, D. Pellegrini, P. Zisopoulos
    CERN, Geneva, Switzerland
  • P. Zisopoulos
    Uppsala University, Uppsala, Sweden
  
  Noise can have a significant impact on the beam dynamics in the LHC, enhancing diffusion processes and leading to emittance blowup. In order to study the details of such effects with computer simulations, a new set of tools is being developed. In particular, a demonstrator GPU-based particle tracker has been built profiting from the technology provided by the NVRTC Cuda library. Its performances for short term beam dynamic simulations in presence of many macro particles are highly promising. In addition, the Numerical Analysis of Fundamental Frequencies (NAFF) algorithm has been thoroughly inspected. Several alternatives to its fundamental steps have been investigated in a modern C++ implementation. The method was also used to produce Frequency Maps and benchmark these tools with other simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB044  
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SUSPSIK068
 Modelling of Curvilinear Electrostatic Multipoles in the Fermilab Muon g-2 Storage Ring  
THPAB055   use link to access more material from this paper's primary paper code  
 
  • A.T. Herrod, S. Jones, A. Wolski
    The University of Liverpool, Liverpool, United Kingdom
  • I.R. Bailey, A.T. Herrod, S. Jones, M. Korostelev, A. Wolski
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • I.R. Bailey, M. Korostelev
    Lancaster University, Lancaster, United Kingdom
  
  Funding: This research was funded by the STFC Cockcroft Institute Core grants no. ST/G008248/1 and ST/P002056/1.
The Fermilab Muon g-2 Experiment (E989) contains flat-plate electrostatic quadrupoles, curved with the reference trajectory as defined by the constant, uniform magnetic dipole field. To understand the beam behaviour at a sufficient level, we require fast, high-accuracy particle tracking methods for this layout. Standard multipole fits to numerically calculated 2D transverse electric field maps have provided a first approximation to the electric field within the main part of the quadrupole, but cannot model the longitudinal curvature or extended fringe fields of the electrostatic plates. Expressions for curvilinear multipoles can be fit to a 2D transverse slice taken from the central point of a numerically calculated 3D electric field map of the quadrupole, providing a curved-multipole description. Generalised gradients can be used to model the fringe field regions. We present the results of curvilinear multipole and generalised gradient fits to the curved quadrupole fields, and the differences in tracking using these fields over 200 turns of a model of the storage ring in BMAD. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB055  
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SUSPSIK069
 Photoinjector Optimization Using a Derivative-Free, Model-Based Trust-Region Algorithm for the Argonne Wakefield Accelerator  
THPAB155   use link to access more material from this paper's primary paper code  
 
  • N.R. Neveu
    IIT, Chicago, Illinois, USA
  • J.M. Larson, J.G. Power
    ANL, Argonne, Illinois, USA
  • L.K. Spentzouris
    Illinois Institute of Technology, Chicago, Illinois, USA
  
  Funding: DE-SC0015479, DE-AC02-06CH11357, DE-AC02-06CH11357
Model-based, trust-region, derivative-free algorithms are increasingly popular for optimizing computationally expensive numerical simulations. A strength of such methods is their efficient use of function evaluations. In this paper, we use one such algorithm to optimize the beam dynamics in two cases of interest at the Argonne Wakefield Accelerator (AWA) facility. First, we minimize the emittance of the electron bunch produced by the AWA drive rf photocathode gun alone by adjusting three parameters: rf gun phase, solenoid strength, and laser radius. The algorithm used converges to a set of parameters with an emittance of 1.08 mm-mrad. Second, we expand the number of optimization parameters to model the complete AWA rf photoinjector linac (the gun and six accelerating cavities). These results are used in a Pareto study of the trade-off between beam emittance and bunch length for the AWA linac. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB155  
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SUSPSIK070
 Preparation of CVD Diamond Detector for fast Luminosity Monitoring of SuperKEKB  
MOPAB027   use link to access more material from this paper's primary paper code  
 
  • C.G. Pang, P. Bambade, D. El Khechen, D. Jehanno, V. Kubytskyi, Y. Peinaud, C. Rimbault
    LAL, Orsay, France
  
  The SuperKEKB e+-e− collider aims to reach a very high luminosity of 8×10 35 cm'2s'1, using highly focused ultra-low emittance bunches colliding every 4ns. To meet the requirement of the dithering feedback system used to stabilize the horizontal orbit at the IP (interaction point), a relative precision of 10 '3 in 1ms is specified for the fast luminosity monitoring, which can be in principle achieved thanks to the large cross section of the radiative Bhabha process. This paper firstly presents the fraction of detected Bhabha scattering positrons with a new beam pipe arrangement coupled with a Tungsten radiator to be installed in the Low Energy Ring; Then the characteristics of signals from a sCVD diamond detector with thickness of 140'm coupled with a broadband current amplifier were studied based on tests with a Sr-90 source; Finally, simulated results for the reconstructed luminosity and the relative precision with different assumed luminosities are also reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB027  
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SUSPSIK071
 Experimental Study of Halo Formation at ATF2  
MOPAB029   use link to access more material from this paper's primary paper code  
 
  • R.J. Yang, P. Bambade, A. Faus-Golfe, V. Kubytskyi, S. Wallon
    LAL, Orsay, France
  • A. Aryshev, T. Naito
    KEK, Ibaraki, Japan
  • N. Fuster-Martínez
    IFIC, Valencia, Spain
  
  For Accelerator Test Facility 2 (ATF2), as well as other high-intensity accelerators, beam halo has been an important aspect reducing the machine performance and activating the components. It is imperative to clearly understand the mechanisms that lead to halo formation and to test the avail- able theoretical models with an adequate experiment setup. In this paper, the experimental measurement of the beam halo formation from beam gas scattering is presented. The upgrading of an OTR/YAG screen monitor for future halo study is also introduced.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB029  
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SUSPSIK072
 Reconstruction of Sub-Femtosecond Longitudinal Bunch Profile Measurement Data  
MOPAB050   use link to access more material from this paper's primary paper code  
 
  • M.K. Weikum, R.W. Aßmann, U. Dorda
    DESY, Hamburg, Germany
  • G. Andonian
    RadiaBeam, Santa Monica, California, USA
  • G. Andonian
    UCLA, Los Angeles, California, USA
  • Z.M. Sheng, M.K. Weikum
    USTRAT/SUPA, Glasgow, United Kingdom
  • Z.M. Sheng
    Shanghai Jiao Tong University, Shanghai, People's Republic of China
  
  With a current trend towards shorter electron beams with lengths on the order of few femtoseconds (fs) to sub-femtoseconds both in conventional and novel accelerator communities, the need for diagnostics with equivalent attosecond resolution is increasing. The proposed design for a sub-femtosecond diagnostic by Andonian et al.* is one such example that combines a laser deflector with an RF deflecting cavity to streak the electron beam in the horizontal and vertical direction. In this paper, we present a tool for the reconstruction of the longitudinal beam profile from this diagnostic data, which can be used both for the analysis of planned experiments and testing of different beam scenarios with respect to their specific setup requirements. Applying this method, the usefulness of the device for measurements in a number of example scenarios, including plasma-accelerated and ultrashort RF-accelerated electron beams, is discussed.
*G. Andonian, E. Hemsing, D. Xiang, P. Mumuseci, A. Murokh, S. Tochitsky, et al, Phys. Rev. Spec. Top-Ac. 14, 072802 (2011). 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB050  
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SUSPSIK073
 Energy Chirp Measurements by Means of an RF Deflector: a Case Study the Gamma Beam Source LINAC at ELI-NP  
MOPAB059   use link to access more material from this paper's primary paper code  
 
  • L. Sabato
    U. Sannio, Benevento, Italy
  • P. Arpaia, A. Liccardo
    Naples University Federico II, Science and Technology Pole, Napoli, Italy
  • A. Mostacci, L. Palumbo
    University of Rome La Sapienza, Rome, Italy
  • A. Variola
    INFN/LNF, Frascati (Roma), Italy
  
  RF Deflector (RFD) based measurements are widely used in high–brightness electron LINAC around the world in order to measure the ultra–short electron bunch length. The RFD provides a vertical kick to the particles of the electron bunch according to their longitudinal positions. In this paper, a measurement technique for the bunch length and other bunch proprieties, based on the usage of an RFD, is proposed. The basic idea is to obtain information about the bunch length, energy chirp, and energy spread from vertical spot size measurements varying the RFD phase, because they add contributions on this quantity. The case study is the Gamma Beam System (GBS), the Compton Source being built in the Extreme Light Infrastructure–Nuclear Physics (ELI–NP) facility. The ELEctron Generation ANd Tracking (ELEGANT) code is used for tracking the particles from RFD to the measurement screen.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB059  
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SUSPSIK074
 Measurement of Three-Dimensional Distribution of Electron Bunch Using RF Transverse Deflector  
MOPAB072   use link to access more material from this paper's primary paper code  
 
  • Y. Nakazato, Y. Koshiba, T. Sasaki, M. Washio
    Waseda University, Tokyo, Japan
  • K. Sakaue
    Waseda University, Waseda Institute for Advanced Study, Tokyo, Japan
  
  We have been studying a high quality electron beam generated by a photocathode RF gun at Waseda University. The electron beam is applied to a pulse radiolysis experiment, laser Compton scattering for soft X-ray generation, and a THz imaging experiment using coherent radiation. In these applications, longitudinal parameters of the electron beam are important. For this reason, we developed the RF deflector system which can directly convert longitudinal distribution of the beam to transverse with high temporal resolution, and performed longitudinal profile measurements of an electron beam from the RF gun. During a series of experiments using an RF deflector, we found that the bunch had a horizontal angle with respect to z axis. Thus we tried to reconstruct the three-dimensional profile of the bunch by computed tomography* in order to visualize the three-dimensional distribution of the bunch. In this conference, we will report the principle of measurement, experimental results of the bunch three-dimensional measurement, and future prospects.
* J. Shi, et al., Reconstruction of the three-dimensional bunch profile by tomography technique with RF deflecting cavity, Nucl. Instrum. Methods Phys. Res., A 752 (2014) 36-41 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB072  
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SUSPSIK075
 Spatial Decoding Electro-Optic Bunch Measurement at Tsinghua Thomson Scattering X-ray Source  
MOPAB077   use link to access more material from this paper's primary paper code  
 
  • W. Wang, Z.J. Chi, Y.-C. Du, W.-H. Huang, C.-X. Tang, L.X. Yan, Z. Zhang
    TUB, Beijing, People's Republic of China
  
  Electron bunches with duration of sub-picosecond are essential in ultraviolet and X-ray free electron laser (XFEL) to reach the desired peak current. Electro-optic (EO) technique is suitable for temporal profile measure-ment of these ultrashort bunches which is one of the key diagnostics in FELs. An electro-optic monitor based on spatial sampling has recently been designed and installed for bunch profile diagnostic at Tsinghua Thomson scat-tering X-ray source (TTX). An ultrashort laser pulse is used to detect the field induced birefringence of the bunch Coulomb field in an electro-optic crystal and the monitor allows direct time-resolved single-shot measure-ment of bunch profile with an accuracy of 135 femtosec-onds for a 40 MeV electron bunch in a non-destructive way, which can simultaneously record the relative time jitter between probe laser and electron bunch. This paper performs the layout of the setup and presents the current measurement results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB077  
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SUSPSIK076
 Design and Simulation of High Order Mode Cavity Bunch Length Monitor for Infrared Free Electron Laser  
MOPAB082   use link to access more material from this paper's primary paper code  
 
  • Q. Wang, X.Y. Liu, P. Lu, Q. Luo, B.G. Sun, L.L. Tang, J.H. Wei, F.F. Wu, Y.L. Yang, T.Y. Zhou, Z.R. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  Funding: Supported by The National Key Research and Development Program of China (2016YFA0401900, 2016YFA0401903); NSFC (11375178, 11575181); the Fundamental Research Funds for the Central Universities (WK2310000046)
A bunch length monitor using resonant cavity has been designed for the NSRL Infrared Free Electron Laser (IR-FEL) facility. To avoid the restriction of working fre-quency caused by the beam pipe radius, the high order modes of the harmonic cavities are utilized. The position and orientation of coaxial probes are optimized to avoid interference modes which come from the cavity and beam tube according to the analysis formula of electro-magnetic field distribution. Based on the parameters of IR-FEL, a simulation is performed to verify the feasibility of the bunch length monitor. The simulation result shows that the design meets the requirements of IR-FEL, and the resolution can be better than 50 fs. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB082  
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SUSPSIK077
 Study on Supports System of BPMs for HEPs  
MOPAB087   use link to access more material from this paper's primary paper code  
 
  • Z.Z. Wang, J.S. Cao, J. He, H.Z. Ma, Y.F. Sui, Z. Wang
    IHEP, People's Republic of China
  
  The High Energy Photon Source(HEPS), a third generation light source with the energy of 6 GeV, is under constructed at IHEP. It has an ultralow emittance (~50pm.rad) and small beam size, thus the requirement of BPM in precision and resolution is quite high. Independent supports with high degree of mechanical and thermal stability will be employed for some special BPMs, such as the BPMs near the insert devices. The supports should have high eigen-frequencies to minimize the amplification of vibration from the ground. Vibrations information of the ground around the supports also need be estimated, with which FEA (finite element analysis) had be utilized to simulate the performance of the supports. Measurements of vibrational stability of the prototype supports have be done and compared with the simulation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB087  
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SUSPSIK078
 First LHC Transverse Beam Size Measurements With the Beam Gas Vertex Detector  
TUOAB1   use link to access more material from this paper's primary paper code  
 
  • A. Alexopoulos, C. Barschel, E. Bravin, G. Bregliozzi, N. Chritin, B. Dehning, M. Ferro-Luzzi, M. Giovannozzi, R. Jacobsson, L.K. Jensen, O.R. Jones, V. Kain, R. Matev, M.N. Rihl, V. Salustino Guimaraes, R. Veness, S. Vlachos, B. Würkner
    CERN, Geneva, Switzerland
  • A. Bay, F. Blanc, S. Gianì, O. Girard, G.J. Haefeli, P. Hopchev, A. Kuonen, T. Nakada, O. Schneider, M. Tobin, Q.D. Veyrat, Z. Xu
    EPFL, Lausanne, Switzerland
  • R. Greim, W. Karpinski, T. Kirn, S. Schael, A. Schultz von Dratzig, G. Schwering, M. Wlochal
    RWTH, Aachen, Germany
  
  The Beam Gas Vertex detector (BGV) is an innovative beam profile monitor based on the reconstruction of beam-gas interaction vertices which is being developed as part of the High Luminosity LHC project. Tracks are identified using several planes of scintillating fibres, located outside the beam vacuum chamber and perpendicular to the beam axis. The gas pressure in the interaction volume is adjusted such as to provide an adequate trigger rate, without disturbing the beam. A BGV demonstrator monitoring one of the two LHC beams was fully installed and commissioned in 2016. First data and beam size measurements show that the complete detector and data acquisition system is operating as expected. The BGV operating parameters are now being optimised and the reconstruction algorithms developed to produce accurate and fast reconstruction on a CPU farm in order to provide real time beam profile measurements to the LHC operators.  
slides icon Slides SUSPSIK078 [3.456 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUOAB1  
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SUSPSIK079
 Diffraction Radiation for Non-Invasive, High-Resolution Beam Size Measurements in Future Linear Colliders  
MOPAB111   use link to access more material from this paper's primary paper code  
 
  • M. Bergamaschi, R. Kieffer, T. Lefèvre, S. Mazzoni
    CERN, Geneva, Switzerland
  • A. Aryshev, N. Terunuma
    KEK, Ibaraki, Japan
  • M. Bergamaschi, P. Karataev, K.O. Kruchinin
    JAI, Egham, Surrey, United Kingdom
  • M. Bergamaschi, P. Karataev, K.O. Kruchinin
    Royal Holloway, University of London, Surrey, United Kingdom
  
  Next generation linear colliders such as the Compact Linear Collider (CLIC) or the International Linear Collider (ILC) will accelerate particle beams with extremely small emittance. The high current and small size of the beam (micron-scale) due to such small emittance require non-invasive, high-resolution techniques for beam diagnostics. Diffraction Radiation (DR), a polarization radiation that appears when a charged particle moves in the vicinity of a medium, is an ideal candidate being non-invasive and allowing beams as small as a few tens of microns to be measured. Since DR is sensitive to beam parameters other than the transverse profile (e.g. its divergence and position), preparatory simulations have been performed with realistic beam parameters. A new dedicated instrument was installed in the KEK-ATF2 beam line in February 2016. At present DR is observed in the visible wavelength range, with an upgrade to the ultraviolet (200nm) planned for spring 2017 to optimize sensitivity to smaller beam sizes. Presented here are the latest results of these DR beam size measurements and simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB111  
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SUSPSIK080
 Applications of Metamaterials for Particle Beam Diagnostics  
MOPAB126   use link to access more material from this paper's primary paper code  
 
  • T.G. Vaughan, P. Karataev
    JAI, Egham, Surrey, United Kingdom
  • V. Antonov
    Royal Holloway, University of London, Surrey, United Kingdom
  • V.V. Soboleva
    RASA Center in Tomsk, Tomsk, Russia
  
  Funding: The work was supported by the Leverhulme Trust through the International Network Grant (IN-2015-012) and the European Union Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 655179 and Russian Governmental Program 'Nauka', N: 0.1656.2016.
Modern and future accelerators, such as linear colliders and X-ray Free Electron Lasers (X-FELs), will be capable of producing femtosecond and sub-femtosecond electron bunches with unprecedented intensity. Non-invasive beam diagnostics will be an integral component of such machines. A new non-destructive method, which employs a Left Handed Metamaterial (LHM), is promising as it provides additional flexibility in the generation and manipulation of radiation compared to techniques which use conventional materials. Simulations of the interaction of a photon beam with the LHM target have been performed using CST Microwave Studio. The range over which the frequency responce is negative can be tuned to the bunch length requirements by varying the parameters of the unit cell such as: the dimensions of the rings and the number of slits in each ring. Simulations have also been performed using Particle Studio on the interaction of an electron beam with the LHM. With a flexible resonance in the terahertz range, this material not only offers applications for ultra short bunch length measurements, but it also opens up the possibility to be used to generate coherent terahertz radiation. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB126  
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SUSPSIK081
 A New Method for Emittance Reconstruction Using a Scraper in a Dispersive Region of a Low Energy Storage Ring  
MOPAB127   use link to access more material from this paper's primary paper code  
 
  • J.R. Hunt, J. Resta-López, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • C. Carli
    CERN, Geneva, Switzerland
  • J.R. Hunt, J. Resta-López, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  Funding: Science and Technology Funding Council, UK CERN
Beam scraping is a standard method for beam emittance measurements at low energies and will be applied at the Extra Low ENergy Antimatter (ELENA) ring. However, in ELENA, as in many other low energy storage rings, the scraper is located in a position of finite dispersion which poses a unique challenge when reconstructing the emittance from beam intensity data. A new algorithm for ELENA and other machines that use a scraper in a dispersive region has been developed. It combines data obtained by scraping the beam from opposite sides with information on the storage ring lattice. In this contribution, the new algorithm is presented, tested using simulations and compared with alternate methods for emittance reconstruction. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB127  
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SUSPSIK082
 Comparison of Optical Transition Radiation Simulations and Theory  
MOPAB138   use link to access more material from this paper's primary paper code  
 
  • J. Wolfenden, R.B. Fiorito, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • M. Bergamaschi, P. Karataev, K.O. Kruchinin
    JAI, Egham, Surrey, United Kingdom
  • M. Bergamaschi, P. Karataev, K.O. Kruchinin
    Royal Holloway, University of London, Surrey, United Kingdom
  • M. Bergamaschi, R. Kieffer, T. Lefèvre
    CERN, Geneva, Switzerland
  • R.B. Fiorito, C.P. Welsch, J. Wolfenden
    The University of Liverpool, Liverpool, United Kingdom
  
  The majority of optical diagnostics currently used will not stand up to the requirements of the next generation of particle accelerators. Current methodologies need innovation to be able to reach the sub-micrometre resolution and sensitivity that will be required. One technique that has the potential to meet these requirements is optical transition radiation (OTR) imaging. A new algorithm is proposed which incorporates OTR theory, optical effects and beam distribution. This algorithm takes an existing method used for beam imaging and pushes the limits resolution beyond that normally attainable. In doing so, it can provide a reliable and economical diagnostic for future accelerators. A discussion on further applications of the algorithm is also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB138  
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SUSPSIK083
 Electron Beam Diagnosis Using K-edge Absorption of Laser-Compton Photons  
MOPAB146   use link to access more material from this paper's primary paper code  
 
  • Y. Hwang, T. Tajima
    UCI, Irvine, California, USA
  • C.P.J. Barty, D.J. Gibson, R.A. Marsh
    LLNL, Livermore, California, USA
  
  Funding: This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
The mean energy, energy spread and divergence of the electron beam can be deduced from laser-Compton scattered X-rays filtered by a material whose K-edge is near the energy of the X-rays. This technique, combined with a spot size measurement of the beam, can be used to measure the emittance of electron bunches, and can be especially useful in LWFA experiments where conventional methods are unavailable. The effects of the electron beam parameters on X-ray absorption images are discussed, along with experimental demonstrations of the technique using the Compact Laser-Compton X-ray Source at LLNL. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB146  
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SUSPSIK084
 Current Status of IPM Linac Control System  
TUPAB042   use link to access more material from this paper's primary paper code  
 
  • S. Haghtalab, F. Abbasi
    Shahid Beheshti University, Tehran, Iran
  • S. Ahmadiannaminpresenter
    ILSF, Tehran, Iran
  • F. Ghasemi, M. Lamehi
    IPM, Tehran, Iran
  
  This paper reports the progress of the control system for IPM 10 MeV accelerator. As an electron linac, it consists of beam injection acceleration tube, radio frequency production and transmission, target, diagnostics and control and safety. In support of this source, an EPICS-based integrated control system has been designed and being implemented from scratch to provide access to the critical control points and continues to grow to simplify operation of the system. In addition to a PLC-based machine protection component and IO interface, a CSS-based suite of control GUI monitors systems including Modulator and RF, Vacuum, Magnets, and electron gun. An overview of this system is presented in this article.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB042  
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SUSPSIK085
 Parameters Calibration and Compensation-Rematch of Failure Cavities in CADS Injector  
TUPIK068   use link to access more material from this paper's primary paper code  
 
  • Y.Z. Jia, W.L. Chen, W.P. Dou, P.H. Gao, H. Jia, S.H. Liu, Y.S. Qin, C. Wang, W.S. Wang, Z.J. Wang
    IMP/CAS, Lanzhou, People's Republic of China
  
  Now when a failure on the China Accelerator Driven System (CADS) is detected, the beam will be stopped by the machine protection system (MPS) immediately. But because of the demand of the beam trip (more than 5 min) rate which should be less than 50 times per year [1], it is important to avoid cutting beam down or recover the beam in a short time. The compensation and rematch is of great importance. If the failure is on a cavity, the other cavities should retune to compensate the beam energy, position and phase in order to recover the beam in short time depending on the time of online calculation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK068  
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SUSPSIK086
 The Configurable Software Interlock System for HLS-II  
TUPIK063   use link to access more material from this paper's primary paper code  
 
  • Y. Song, G. Liu, K. Xuan
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  The interlock system is an essential component for an accelerator facility. A configurable software interlock system(SIS) is designed for Hefei Light Source II (HLS-II), which complements the hardware interlock system to ensure equipment and operators' safety. The system is developed using Python under the EPICS framework with the method of separating the configuration file from the interlock program. The interlock logic is completely determined by the configuration file and its nested tree structure is easy to expand. The test results indicate that the new software interlock system is reliable, flexible and convenient to operate. This paper will describe the design and the construction of HLS-II SIS.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPIK063  
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SUSPSIK087
 Evaluation of Digital LLRF Control System Performance at STF in KEK  
THPAB116   use link to access more material from this paper's primary paper code  
 
  • S.B. Wibowo, N. Liu
    Sokendai, Ibaraki, Japan
  • T. Matsumoto, S. Michizono, T. Miura, F. Qiu
    KEK, Ibaraki, Japan
  
  The Superconducting RF Test Facility (STF) at the High Energy Accelerator Research Organization (KEK) was built for research and development of the International Linear Collider (ILC). Several digital low-level radio frequency (LLRF) control systems were developed at the STF. The purposes of these developments are to construct a minimal configuration of the ILC LLRF system and achieve the amplitude and phase stability of the accelerating field in the superconducting accelerator. Evaluations of digital LLRF control systems were conducted during the conditioning of eight superconducting cavities performed between October and November 2016. The digital LLRF control system configured for ILC was demonstrated and the performance fulfilled the required stability criteria of the accelerating field in the ILC. These evaluations are reported in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB116  
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SUSPSIK088
 Orbit and Dispersion Tool at European XFEL Injector  
THPAB092   use link to access more material from this paper's primary paper code  
 
  • N. Ghazaryan
    CANDLE SRI, Yerevan, Armenia
  • M.E. Castro Carballo, W. Decking
    DESY, Hamburg, Germany
  
  Trajectory and electron beam size play an essential role in Free Electron Laser (FEL) obtainment. Since transverse dispersion changes off-energy particle trajectories and increases the effective beam size, dispersion and orbit must constantly be controlled and corrected along the whole lattice. In this paper the principles underlying the orbit and dispersion correction tool, developed at DESY, are described. The results of its testing on European XFEL injector are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB092  
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SUSPSIK089
 The Study of Accelerator Data Archiving and Retrieving Software  
THPAB121   use link to access more material from this paper's primary paper code  
 
  • Y.S. Qiao, G. Lei, Z. Zhao
    IHEP, Beijing, People's Republic of China
  
  This paper presents a novel archiving and retrieving software designed for BEPC-II and other particle accelerators. At BEPC-II, real-time data are stored as index files recorded by traditional EPICS Channel Archiver. Never-theless, index files are not suitable for long-term maintenance and difficult for data analysis. The NoSQL database MongoDB is used for this new system due to aging technologies, so as to promote the data storage reliability, usability, and possible future advanced data analysis. A cross-platform UI (User Interface) has also been developed to make it quicker and easier to access the database. The writing and query performance are tested for this software.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB121  
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SUSPSIK090
 Beam Dynamics for the ThomX Linac  
THPIK008   use link to access more material from this paper's primary paper code  
 
  • L. Garolfi, C. Bruni, M. El Khaldi, C. Vallerand
    LAL, Orsay, France
  
  We report the results of a recent beam dynamics study that has led to promising working points for the split ThomX photoinjector. ThomX is a back-scattering Thomson light source that will use S-band electron Linac with an energy of 50 MeV to produce 45 keV high X-rays flux (1011 - 1013 ph/s), by means of collision between electron bunches and laser pulses, in the energy range from 45 keV to 90 keV. Since Thomx has been conceived to maximise the average X-rays flux in a fixed bandwidth, the high rate electron-photon collisions impose a linear accelerator combined with a storage ring. The high performances of the accelerator are largely affected by the high quality of the electron beam at the interaction point in the ring. Beam specifications should be achieved at the interaction point to the extent that 1 nC, 50 nA average current per bunch with normalised rms transverse emittance less than 5 mm and around 0.3% energy spread, at the end of the linac. The beam dynamics along the linac has been studied to demonstrate the capability of the accelerator to meet the requirements for the high brightness electron beam using an RF photoinjector configuration.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK008  
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SUSPSIK091
 Structural Mechanical Analysis of 4-Rod RFQ Structures in View of a Newly Revised CW RFQ for the HLI at GSI  
THPIK021   use link to access more material from this paper's primary paper code  
 
  • D. Koser, H. Podlech
    IAP, Frankfurt am Main, Germany
  • P. Gerhard, L. Groening
    GSI, Darmstadt, Germany
  • O.K. Kester
    TRIUMF, Vancouver, Canada
  
  Funding: BMBF Contr. No. 05P15RFRBA
The High Charge State Injector (HLI) at the GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, serves as one of the two injector linacs for the UNILAC as well as dedicated injector for the upcoming cw linac project for super heavy element research. As the front end of the HLI is planned to be upgraded for cw operation a newly revised cw capable RFQ structure with an operating frequency of 108 MHz is required. The existent 4-rod structure, which was commissioned at the HLI in 2010, suffers from severe modulated rf power reflections originating from mechanical oscillations of the electrodes that both limit the achievable performance and impede stable operation*. Besides preceding vibration measurements that were done by GSI using a laser vibrometer**, the structural mechanical behavior of the 4-rod geometry was extensively analyzed using ANSYS Workbench. Thereby the crucial mechanical eigenmodes could be identified and their impact on the rf properties was investigated by simulations using CST MWS. A completely newly revised 4-rod RFQ design with optimized structural rigidity was developed of which a 6-stem prototype is currently being manufactured.
*P. Gerhard et al., Experience With a 4-Rod CW Radio Frequency Quadrupole, LINAC12, THPLB07
**P. Gerhard et al., In Situ Measurements of Mechanical Vibrations of a 4-Rod RFQ at GSI, LINAC14, TUPP057 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK021  
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SUSPSIK092
 Design and Construction of 126 MHz Capacity Loaded Aluminium Cavity Prototype  
THPVA085   use link to access more material from this paper's primary paper code  
 
  • S. Ahmadiannamin, J. Rahighi, Kh.S. Sarhadi
    ILSF, Tehran, Iran
  • F. Abbasi
    Shahid Beheshti University, Tehran, Iran
  • M. Lamehi Rashti
    IPM, Tehran, Iran
  
  Iranian light source Facility (ILSF)isa 3 GeV Ultra low emittance synchrotron with 528 meter circumference that will be constructed in the city of Qazvin, located 150km west of Tehran. Motivated by the development of HOM damped cavity with simpler structure at 100 MHz at MAX Lab and also lower costs, 100 MHz RF system is envisaged for ILSF booster and storage ring. An RF cavity prototype was fabricated for better understandingof characteristics of capacity loaded RF cavities by practical investigation. In this paper, design and development of this prototype is presentedwith the simulation and measurement results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA085  
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SUSPSIK093
 Design and Optimization of a 2MeV X-Band Side Coupled Accelerating Structure  
THPIK043   use link to access more material from this paper's primary paper code  
 
  • H. Yuan
    IHEP, Beijing, People's Republic of China
  
  An X-band bi-period side-coupled accelerating structure has been designed in this paper. The structure's working frequency is 9.3GHz. '/2 mode is chosen for the structure's stability. There are 11 accelerating cells, the first 5 work as non-light velocity part while the other 6 work as light velocity part. After CST simulation, the coupling constant between accelerating cells and coupling cells is 5%, efficient shunt impedance is 142M'/m. For the beam dynamic analysis, the particle energy is selected to be 2 MeV and the peak current is 60 mA for the radiation dosage limits by national standard. After Pamela optimization, the particle's capture efficiency is more than 30%. To feed power into the structure, a coupler is designed in the middle of the structure and the coupling coefficient is 1.4. The structure is manufactured and the measurement result accords well with designing value.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK043  
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SUSPSIK094
 A C-Band Compact Spherical RF Pulse Compressor for the SXFEL Linac Energy Upgrade  
THPIK067   use link to access more material from this paper's primary paper code  
 
  • Z.B. Li, W. Fang, Q. Gu, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  
  A new compact C-band (5712 MHz) spherical RF pulse compressor has been designed for Shanghai Soft X-ray Free Electron Laser (SXFEL) facility energy upgrading at Shanghai Institute of Applied Physics (SINAP), Chinese Academy of Sciences (CAS). This pulse compressor contains one high Q0 spherical RF resonant cavity which works on two TE113 modes and a novel coupler. As there is only one storage cavity, this pulse compressor can be much smaller than the traditional SLED. With the coupling coefficient 4.9, the average power gain can be as high as 3.8. In this paper, the scheme of the C-band spherical pulse compressor and RF design are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK067  
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SUSPSIK096
 Design and Construction of a High-Gradient RF Lab at IFIC-Valencia  
THPIK081   use link to access more material from this paper's primary paper code  
 
  • A. Vnuchenko, T. Argyropoulos, C. Blanch Gutiérrez, D. Esperante Pereira, A. Faus-Golfe, J. Giner Navarro
    IFIC, Valencia, Spain
  • N. Catalán Lasheras, G. McMonagle, I. Syratchev, W. Wuensch
    CERN, Geneva, Switzerland
  • A. Faus-Golfe
    LAL, Orsay, France
  
  The IFIC High-Gradient (HG) Radio Frequency (RF) laboratory is designed to host a high-power infrastructure for testing HG S-band normal-conducting RF accelerating structures and has been under construction since 2016. The main objective of the facility is to develop HG S-band accelerating structures and to contribute to the study of HG phenomena. A particular focus is RF structures for medical hadron therapy applications. The design of the laboratory has been made through collaboration between the IFIC and the CLIC RF group at CERN. The layout is inspired by the scheme of the Xbox-3 test facility at CERN, and it has been adapted to S-band frequency. In this paper we describe the design and construction status of such a facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK081  
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SUSPSIK097
 Ultra High Gradient Breakdown Rates in X-Band Cryogenic Normal Conducting Rf Accelerating Cavities  
THPIK125   use link to access more material from this paper's primary paper code  
 
  • A.D. Cahill, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
  • V.A. Dolgashev, S.G. Tantawi, S.P. Weathersby
    SLAC, Menlo Park, California, USA
  
  Funding: Work Supported by DOE/SU Contract DE-AC02-76-SF00515, US NSF Award PHY-1549132, the Center for Bright Beams, and DOE SCGSR Fellowship.
RF breakdown is one of the major factors limiting the operating accelerating gradient in rf particle accelerators. We conjecture that the breakdown rate is linked to the movements of crystal defects induced by periodic mechanical stress. Pulsed surface heating possibly creates a major part of this stress. By decreasing crystal mobility and increasing yield strength we hope to reduce the breakdown rate for the same accelerating gradient. We can achieve these properties by cooling a copper accelerating cavity to cryogenic temperatures. We tested an 11.4 GHz cryogenic copper accelerating cavity at high power and observed that the rf and dark current signals are consistent with Q0 changing during rf pulses. To take this change in Q0 into account, we created a non-linear circuit model in which the Q0 is allowed to vary inside the pulse. We used this model to process the data obtained from the high power test of the cryogenic accelerating structure. We present the results of measurements with low rf breakdown rates for surface electric fields near 500 MV/m for a shaped rf pulse with 150 ns of flat gradient. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK125  
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SUSPSIK098
 Fabrication Studies of a 650 MHz Superconducting RF Deflecting Mode Cavity for the ARIEL Electron Linac  
MOPAB022   use link to access more material from this paper's primary paper code  
 
  • D.W. Storey, R.E. Laxdal, B. Matheson, N. Muller
    TRIUMF, Vancouver, Canada
  • D.W. Storey
    Victoria University, Victoria, B.C., Canada
  
  A 650 MHz RF deflecting mode cavity is required for the ARIEL electron Linac to separate interleaved beams bound for either rare isotope production or a recirculation loop containing a Free Electron Laser. An RF separator will allow both modes to run simultaneously by imparting opposite transverse deflection to adjacent bunches at 1.3 GHz. The SRF cavity has been designed to provide up to 0.6 MV transverse voltage for operation with up to a 50 MeV CW electron beam. The design was optimised for compact geometry with high shunt impedance. Due to the low dissipated power, the cavity will operate at 4 K and allows for investigations into low cost fabrication techniques. The cavity is being machined from bulk reactor grade ingot Niobium and welds will be performed using TIG welding in an ultra-pure Argon chamber. Results of fabrication studies will be presented as well as measurements performed on a copper prototype cavity.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPAB022  
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SUSPSIK099
 Setup of a Spatially Resolving Vector Magnetometry System for the Investigation of Flux Trapping in Superconducting Cavities  
MOPVA050   use link to access more material from this paper's primary paper code  
 
  • B. Schmitz, K.Alomari. Alomari, J. Knobloch, O. Kugeler, J.M. Köszegi, Y. Tamashevich
    HZB, Berlin, Germany
  
  Flux trapping is the major contribution to the residual resistance of superconducting cavities. In order to gain a better understanding of the mechanisms involved and aiming at an eventual minimization of trapped flux, a measurement setup based on AMR sensors was devised that allows for monitoring the magnetic field vector at various positions near the cavity surface. First results of the efforts are presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA050  
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SUSPSIK100
 Upgrade of the Capture Section of the S-DALINAC Injector  
MOPVA055   use link to access more material from this paper's primary paper code  
 
  • D.B. Bazyl, H. De Gersem, W.F.O. Müller
    TEMF, TU Darmstadt, Darmstadt, Germany
  
  Funding: This work is supported by the DFG through GRK 2128.
In order to reduce the energy spread of the recirculated beam, the injector of the S-DALINAC needs to be optimized, because the non-isochronous recirculation cannot correct for errors originating from the injector linac. For the S-DALINAC, spatial restrictions suggest the use of SRF technology for the capture section. In this work, we consider various SRF cavities with an operating frequency of 3 GHz for a possible upgrade of the capture section of the S-DALINAC. The first results of the RF and beam dynamics simulations for the proposed options are presented in this paper. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA055  
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SUSPSIK101
 PLASMA PROCESSING R&D OF THE 1.3 GHZ SINGLE-CELL SRF CAVITY AT IMP  
MOPVA082   use link to access more material from this paper's primary paper code  
 
  • L. Yang, L. Chen, Y. He, S.C. Huang, C.X. Li, C.L. Li, Y.M. Li, L. Lu, A. Shi, L.P. Sun, A.D. Wu, S.H. Zhang
    IMP/CAS, Lanzhou, People's Republic of China
  
  The China-Accelerator Driven Sub-critical System (C-ADS) injector II has already commissioned with a CW 1 mA and a pulsed 10 mA proton beam. The beam energy achieved 10 MeV. The superconducting linac (SCL) is routinely operating at 4.7 MV/m average accelerating gradient in the low-beta cryomodules. Field emission and surface contaminants of the SCL limit the gradient in-crease in the beam commissioning. Hence, in order to increase the SCL accelerating gradient, reduce field emis-sion and remove surface pollutants, in-situ plasma pro-cessing R&D in a 1.3 GHz single-cell SRF cavity has being studied. In this paper, the current effort of plasma processing R&D in a 1.3 GHz single-cell SRF cavity will be presented in details and the future plan will be also reported.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA082  
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SUSPSIK102
 Materials Characterization for SRF Cavities: Gaining Insight Into Nb3Sn  
MOPVA114   use link to access more material from this paper's primary paper code  
 
  • J. Tuggle
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  • G.V. Eremeev, A.D. Palczewski, C.E. Reece
    JLab, Newport News, Virginia, USA
  • M.J. Kelley, U. Pudasaini
    The College of William and Mary, Williamsburg, Virginia, USA
  
  Funding: JLab work supported by U.S. DOE Contract No. DE-AC05-06OR23177. Work at William & Mary and Virginia Tech supported by the Office of High Energy Physics, U.S. Department of Energy grant DE-SC-0014475
Although SRF accelerators are an invaluable research tool they can be painfully expensive to construct and operate at the current level of SRF technology. This cost is significantly due to the necessity to operate at a temperature of only 2K. Considerable research is currently underway into next generation SRF cavity technologies such as Ndoping and Nb3Sn coating. Both of these technologies will lower the cryogenic load of accelerators, correspondingly lowering both construction and operating costs. However, current understanding of either technology is incomplete and in order to elucidate the underlying mechanisms there is a need to push current characterization methods forward. In this work, ion beam techniques (e.g. focused ion beam (FIB)), and electron backscatter diffraction (EBSD) were applied to help understand Nb3Sn coating mechanisms. This presentation will focus on characterization, providing examples of EBSD work, along with discussion of some of the issues encountered while trying to produce high quality EBSD data. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA114  
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SUSPSIK103
 Impact of Trapped Magnetic Flux and Thermal Gradients on the Performance of Nb3Sn Cavities  
MOPVA118   use link to access more material from this paper's primary paper code  
 
  • D.L. Hall, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • D. Liarte, J.P. Sethna
    Cornell University, Ithaca, New York, USA
  
  Trapped magnetic flux is known to degrade the quality factor of superconducting cavities by increasing the surface losses ascribed to the residual resistance. In Nb3Sn cavities, which consist of a thin layer of Nb3Sn coated on a bulk niobium substrate, the bimetallic interface results in a thermal current being generated in the presence of a thermal gradient, which will in turn generate flux that can be trapped. In this paper we quantify the impact of trapped flux, from either ambient fields or thermal gradients, on the performance of the cavity. We discover that the sensitivity to trapped flux, a measure of the increase in residual resistance as a function of the amount of flux trapped, is a function of the accelerating gradient. A theoretical framework to explain this phenomenon is proposed, and the impact on the requirements for operating a Nb3Sn cavity in a cryomodule are considered.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA118  
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SUSPSIK104
 Effectiveness of Chemical Treatments for Reducing the Surface Roughness of Nb3Sn  
MOPVA124   use link to access more material from this paper's primary paper code  
 
  • R.D. Porter, F. Furuta, D.L. Hall, M. Liepe, J.T. Maniscalco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: DOE DE-SC008431, NSF-PHY 1549132, NSF DMR-1120296
Current Niobium-3 Tin (Nb3Sn) superconducting radio-frequency (SRF) accelerator cavities have rougher surfaces than conventional electropolished Niobium accelerator cavities. The surface roughness can cause enhancement of the surface magnetic field, pushing it beyond the critical field. If this occurs over a large enough area it can cause the cavity to quench. The surface roughness may cause other effects that negatively impact cavity quality factor (Q) performance. Reducing surface roughness of Nb3Sn cavities may be necessary to achieve higher gradient with high Q. Current chemical treatments for reducing the surface roughness of Niobium are challenging for Nb3Sn: the Nb3Sn layer is only ~2 um thick while it is difficult to remove less than 1 mu uniformly with most chemical treatments. This paper presents measurements of the surface roughness before and after Buffered Chemical Polish, Electropolishing and oxipolishing. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA124  
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SUSPSIK105
 Multipacting Behavior Study for the 112 MHz Superconducting Photo-Electron Gun  
MOPVA140   use link to access more material from this paper's primary paper code  
 
  • I. Petrushina
    SUNY SB, Stony Brook, New York, USA
  • V. Litvinenko, G. Narayan, I. Pinayev, F. Severino, K.S. Smith
    BNL, Upton, Long Island, New York, USA
  • V. Litvinenko
    Stony Brook University, Stony Brook, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Superconducting 1.2 MV 112 MHz quarter-wave photo-electron gun (SRF gun) is used as a source of electron beam for the Coherent electron Cooling experiment (CeC) at BNL. During the CeC commissioning we encountered a number of multipacting zones in the gun. It was also observed that introduction of CsK2Sb photocathode creates additional multipacting zone. This paper presents numerical and experimental study of the multipactor discharge in the SRF gun. We also discuss ways of crossing the multipacting levels to the operational voltage. Finally, we compare the results of our numerical simulations of the multipactor discharge using ACE3P with experimental data. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA140  
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SUSPSIK106
 Post-Processing of Nb3Sn Coated Nb  
MOPVA144   use link to access more material from this paper's primary paper code  
 
  • U. Pudasaini, M.J. Kelley
    The College of William and Mary, Williamsburg, Virginia, USA
  • G.V. Eremeev, M.J. Kelley, C.E. Reece
    JLab, Newport News, Virginia, USA
  • M.J. Kelley, J. Tuggle
    Virginia Polytechnic Institute and State University, Blacksburg, USA
  
  Funding: Supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics under contract DE­AC05­06OR23177 and Office of High Energy Physics under grant SC00144475.
Practical SRF cavities may be subjected to one or more processes after nominally complete preparation. Successful implementation of such processes in Nb3Sn coated cavities requires the understanding of material's response to these treatments. SRF-grade Nb samples, coated with Nb3Sn by the widely used tin vapor diffusion process were subjected to one or more of the following: hydrofluoric acid (HF) rinsing, oxypolishing, buffered chemical polishing (BCP) or electrochemical treatment. They were examined by materials characterization tech-niques including scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), atomic force microscopy (AFM), and X-ray photoelectron spec-troscopy (XPS). The effects compared to niobium are different enough in most cases that further development is desirable to routinely obtain a favorable result. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-MOPVA144  
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SUSPSIK107
 Development of 1.3 GHz Cavity Combiner for 24 kW CW SSA  
THPAB127   use link to access more material from this paper's primary paper code  
 
  • W. Liu, B. Du, G. Huang, L. Lin, L. Shang, W.B. Song
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  The 24KW CW SSA (Solid-State Amplifier) is being developed to drive the 1.3GHz SC Linac used in a THz light source. The SSA adopts the compact all-in-one combining method ' cavity combiner, which is proposed and developed in recent years. This paper reports the R&D of the cavity combiner. The cavity combiner resonates in TM010 mode, coupling with 24 coaxial-connected 1kW amplifier modules. The cavity's electromagnetic characteristic is calculated by CST, and the mechanical structure including the input and output coupler has been designed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPAB127  
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SUSPSIK108
 Development of High Power RF Amplifier System for the KBSI RFQ  
THPIK072   use link to access more material from this paper's primary paper code  
 
  • J. Bahng
    Kyungpook National University, Daegu, Republic of Korea
  • M.-H. Chun
    PAL, Pohang, Kyungbuk, Republic of Korea
  • J.G. Hong, B.S. Lee, J.W. Ok
    Korea Basic Science Institute, Busan, Republic of Korea
  • D.S. Kim
    DAWONSYS, Ansan-si, Republic of Korea
  • E.-S. Kim
    Korea University Sejong Campus, Sejong, Republic of Korea
  
  KBSI (Korean Basic Science Institute) has been developed a compact accelerator system for generation of fast neutron by 2.7 MeV/u of lithium beam. The facility consists of 28 GHz SC-ECR ion source, LEBT, RFQ and DTL. The developed RFQ accelerator provides lithium ion beam from 12 keV/u to 500 keV/u with 98.88 % of high transmission rate at 165 MHz of operation frequency. RF power system for RFQ accelerator has been developed to provide sufficient RF power into RFQ cavity. which consists of LLRF system for control, 5 KW of SSPA as IPA, tetrode tube amplifier as FPA, coaxial transmission line and circulator for protection from reflection power provides 100 kW at operation frequency with CW mode, In this paper, we discuss about development of RF system and performance test in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPIK072  
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SUSPSIK109
 Topology Optimization for a Superconducting Cyclotron Main Magnet  
WEPVA081   use link to access more material from this paper's primary paper code  
 
  • L.G. Zhang, K. Fan, S. Hu, L.X.F. Li, Z.Y. Mei, B. Qin, Z.J. Zeng
    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
  
  Main magnet is the heaviest component in a superconducting cyclotron, which occupies a large amount of cost. Topology optimization method is implanted to minimize the weight of main magnet while keep the field performance, which will make significant economic benefit. Due to the powerful superconducting coils, the main magnet is driven into saturation, and the nonlinear effect of the material must be considered. If the ordinary standard density method is used for the main magnet structure optimization, the nonlinear B-H relation have to be interpolated and the sensitivity analysis is very complicated. In this paper, a proper 2D model is established and the optimization formulation is given using standard density method. Then, the optimized topology of the main magnet for a 250MeV superconducting proton cyclotron is designed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA081  
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SUSPSIK110
 Change of Critical Current Density in Nb-Ti and Nb3Sn Strands After Millisecond Heating  
WEPVA111   use link to access more material from this paper's primary paper code  
 
  • V. Raginel, K. Kulesz, M. Mentink, R. Schmidt, A.P. Verweij, D. Wollmann
    CERN, Geneva, Switzerland
  • D. Kleiven
    NTNU, Trondheim, Norway
  
  The damage mechanisms and limits of superconducting magnet components due to direct beam impact are not well understood. The energy deposition from beam losses can cause significant temperature rise and mechanical stress in the magnet coils, which can lead to a degradation of the insulation strength and critical current of the superconductor. An improved understanding of these mechanisms is not only important for the LHC in view of the planned increase in beam brightness, but also for other high energy accelerators using superconducting magnets. An experimental road map has been defined to study these damage mechanisms. Experiments have been performed with Nb-Ti and Nb3Sn strands and cable stacks at room temperature. This contribution focuses on the experimental study on the effect of millisecond heating on superconducting strands.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA111  
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SUSPSIK111
 Design and Development of Accelerator Magnet Power Supply Based on SiC-MOSFET  
WEPVA068   use link to access more material from this paper's primary paper code  
 
  • L. Yang, F. Long, Z.H. ZhenHua
    IHEP, Beijing, People's Republic of China
  
  SiC is a new type of semiconducting material with rapid development after the first generation and the second generation of semiconductor materials represented by silicon and gallium arsenide. SiC-MOSFET has a high frequency, high breakdown voltage, high temperature, radiation and many other points, suitable for future use in the accelerator magnet power supply. In this paper, the development and operation of a SiC-MOSFET-based accelerator magnet power supply are described in detail. The experiment results show that the performance of this power supply is superior to that of the same specification using Si-MOSFET. The power supply adopts one-way AC power supply, and the output stage adopts the full bridge circuit topology. The power device adopts C2M0040120D SiC-MOSFET, the working frequency is 30 kHz, the output current is ± 20A, the output voltage is ± 20V, and power is 400W. The Digital Power Supply Control Module (DPSCM) is used to realize high-precision digital closed-loop control, which supports on-line debugging and PC control. Power supply can be used to correct the magnet power, with high efficiency, high stability, and fast response and so on.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA068  
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SUSPSIK112
 Design of the New CERN nTOF Neutron Spallation Target: R&D and Prototyping Activities  
WEPVA102   use link to access more material from this paper's primary paper code  
 
  • R. Esposito, M. Calviani, T. Coiffet, M. Delonca, L. Dufay-Chanat, E. Gallay, M. Guinchard, D. Horvath, T. Koettig, A.P. Perez, A.T. Perez Fontenla, A. Perillo-Marcone, S. Sgobba, M.A. Timmins, A. Vacca, V. Vlachoudis
    CERN, Geneva, Switzerland
  • M. Beregret
    UTBM, Belfort, France
  • L. Gomez Pereira
    University of Vigo, Pontevedra, Spain
  • F. Latini
    University of Rome La Sapienza, Rome, Italy
  • R. Logé
    EPFL, Lausanne, Switzerland
  
  A new spallation target for the CERN neutron time-of-flight facility will be installed during Long Shutdown 2 (2019-2020), with the objective of improving operational reliability, avoiding water contamination of spallation products, corrosion/erosion and creep phenomena, as well as optimizing it for the 20 m distant vertical experimental area 2, whilst keeping the same physics performances of the current target at the 200 m far experimental area 1. Several solutions have been studied with FLUKA Monte Carlo simulations in order to find the optimal solution with respect to neutron fluence, photon background, resolution function, energy deposition and radiation damage. Thermo-mechanical studies (including CFD simulations) have been performed in order to evaluate and optimize the target ability to withstand the beam loads in terms of maximum temperatures reached, cooling system efficiency, maximum stresses, creep and fatigue behaviour of the target materials, leading to a preliminary mechanical design of the target. This paper also covers the further prototyping and material characterization activities carried out in order to validate the feasibility of the investigated solutions.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-WEPVA102  
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SUSPSIK113
 The Preliminary Performance of the Timing and Synchronization System at Tsinghua University  
THPVA055   use link to access more material from this paper's primary paper code  
 
  • Z.Y. Lin, Y.-C. Du, W.-H. Huang, W.-H. Huang, C.-X. Tang, C.-X. Tang, J. Yang
    TUB, Beijing, People's Republic of China
  • J.M. Byrd, L.R. Doolittle, G. Huang, Q. Qiang, R.B. Wilcox, Y.L. Xu
    LBNL, Berkeley, California, USA
  
  A precise timing and synchronization system is developed in Tsinghua University(THU). The whole system scheme includes fiber-based CW carrier phase reference distribution system (PRDS) for delivering stabilized RF phase reference to multiple receiver clients, Low Level RF (LLRF) control system to stabilized the accelerating mi-crowave field and laser-RF synchronization system for high precise synchronization of optical and RF signals. The system test and the demonstration experiment of each subsystem are carried on to evaluate the system and the phase error jitter resources are analysed.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA055  
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SUSPSIK114
 Vibration Study of Magnet Girder of the HEPS-TF  
THPVA051   use link to access more material from this paper's primary paper code  
 
  • Z. Wang, C. H. Li, H. Qu, H. Wang
    IHEP, Beijing, People's Republic of China
  
  Abstract: There are stringent requirements on beam stability in the High Energy Photon Source (HEPS). The stability of the magnet girder is an extremely important factor for the beam stability. This paper will discuss the influence of ground vibration to the beam stability. This influence will determine the scope of the vibration magnification of the magnet girder. By improving the stiffness of the magnet girder, the influence will be reduced and the beam stability shall be improved. Besides, the progress of the HEPS-TF girder prototype and the vibration test will be described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA051  
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SUSPSIK115
 Cooling and Thermo Stabilization System of 100MeV/100kW Electron Linear Accelerator of Neutron Source Driver  
THPVA070   use link to access more material from this paper's primary paper code  
 
  • M. Moisieienko, I.M. Karnaukhov, A. Mytsykov, A.Y. Zelinsky
    NSC/KIPT, Kharkov, Ukraine
  
  Cooling system and temperature control technology elements of the linear electron accelerator of 100 MeV/100kW is a complex technological system composed of three subsystems: the cooling klystron gallery equipment (30 C ± 1), cooling of the accelerator tunnel equipment (30 C ± 1) and the cooling and temperature control accelerating sections and waveguide (40 ° C ± 0,2). The block diagram of cooling and temperature control of the linear electron accelerator of 100 MeV/100 kW, describes the basic principles to formulate requirements to the cooling systems. It describes the status of the installation, commissioning and testing of the cooling and temperature control of the accelerator - driver subcritical neutron source KIPT.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA070  
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SUSPSIK116
 Central Region Design for a Superconducting Cyclotron in the HUST Proton Therapy Facility  
THPVA111   use link to access more material from this paper's primary paper code  
 
  • Z.Y. Mei, K. Fan, S. Hu, L.X.F. Li, Z.J. Zeng, L.G. Zhang
    HUST, Wuhan, People's Republic of China
  
  A 250 MeV isochronous superconducting cyclotron was adopted in the HUST proton therapy facility. Since the proton beam quality is often limited by the parameters of the central region, special care is given to the design and optimization of the central region to obtain a qualified proton beam using for treatment. An internal proton PIG source with constant arc current is adopted to meet the stability requirements of the beam. Furthermore, a puller followed by an adjustable slit and a fixed vertical collimator are installed to maintain a good centering and vertical focusing beam with maximum intensity. In order to meet the requirement of the intensity modulated proton therapy (IMPT), a vertical kicker is used just followed the puller. The central region structure is optimized iteratively with the simulation results of the OPERA3D and the CYCLONE code. An optimum central region structure has been obtained with RF phase acceptance is around 24°. This paper presents the design parameters of the central region and the results of the proton beam simulation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA111  
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SUSPSIK117
 Modelling PET Radionuclides Production in Tissue and External Targets Using Geant4  
THPVA130   use link to access more material from this paper's primary paper code  
 
  • A. Amin, R.J. Barlow
    IIAA, Huddersfield, United Kingdom
  • C.M. Hoehr, C. Lindsay
    TRIUMF, Vancouver, Canada
  • A. Infantino
    CERN, Geneva, Switzerland
  
  The Proton Therapy Facility in TRIUMF provides 74 MeV protons extracted from a 500 MeV H− cyclotron for ocular melanoma treatments. During treatment, positron emitting radionuclides such as C-11, O-15 and N-13 are produced in patient tissue. Using PET scanners, the isotopic activity distribution can be measured for in-vivo range verification. A second cyclotron, the TR13, provides 13 MeV protons onto liquid targets for the production of PET radionuclides such as F-18, N-13 or Ga-68, for medical applications. The aim of this work was to validate Geant4 against FLUKA and experimental measurements for production of the above-mentioned isotopes using the two cyclotrons. The results show variable degrees of agreement. For proton therapy, the proton-range agreement was within 2 mm for C-11 activity, whereas N-13 disagreed. For liquid targets at the TR13 the average absolute deviation ratio between FLUKA and experiment was 1.9±2.8, whereas the average absolute deviation ratio between Geant4 and experiment was 0.6±0.4. This is due to the uncertainties present in experimentally determined reaction cross sections.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA130  
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SUSPSIK118
 Inverse Problem-Based Magnetic Characterization of Weekly Magnetic Alloys  
THPVA113   use link to access more material from this paper's primary paper code  
 
  • A. Parrella, M.P. Ramos
    IT, Lisboa, Portugal
  • P. Arpaia, A. Liccardo
    Naples University Federico II, Science and Technology Pole, Napoli, Italy
  • M.C.L. Buzio
    CERN, Geneva, Switzerland
  
  Understanding the magnetic properties of materials used in accelerator components is becoming more and more important. For example, in the upcoming LHC upgrade at CERN, the increasing luminosity will boost the radiation dose received by the accelerator magnet's coil and consequently decrease its lifespan. Hence, a radiation shield with relative permeability less than 1.005 is required. The goal of this research is to design and validate a new method for characterizing weekly magnetic materials, suitable to be used in quality control of series production. The proposed method is based on inverse analysis approach coupled with a finite-element model. A material with unknown permeability is inserted in the air gap of a dipole magnet and the consequent perturbations of the dipole background flux density are measured. The magnetic permeability is then identified through gray-box inverse modelling, based on a finite-element approach. The results have been used to predict the magnetic impact of the radiation shield and develop further research on this subject.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA113  
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SUSPSIK119
 Monte Carlo Simulation of Electron Beam Irradiation System for Natural Rubber Vulcanization  
THPVA126   use link to access more material from this paper's primary paper code  
 
  • K. Kosaentor
    IST, Chiang Mai, Thailand
  • E. Kongmon, S. Rimjaem, J. Saisut, C. Thongbai
    Chiang Mai University, Chiang Mai, Thailand
  
  This paper presents the results of Monte Carlo simulation of electron beam irradiation system for natural rubber vulcanization, which is underway at Chiang Mai University in Thailand. The accelerator system can produce electron beams with adjustable energy and current in the ranges of 0.5-4 MeV and 10-100 mA, respectively. The electron beam exits from vacuum environment in the accelerator to the atmospheric air through a titanium (Ti) window. The electron dose absorption in Ti window and air was calculated by using the program GEANT4. The simulation results show that 50 μm Ti foil causes the energy loss of 1 and 18% for the beam of 4.0 and 0.5 MeV, respectively. The air gap between vacuum window and rubber surface is adjustable from 180 mm to 540 mm. The total beam energy loss of around 8-17% and 1-3% from the initial energies of 0.5 and 4 MeV, respectively. The proper depth of the natural rubber for the vulcanization process is 0.13 to 1.68 cm with the surface dose of 5.32 kGy for 0.5 MeV electron beam and 3.34 kGy for 4.0 MeV electron beam at the pulse repetition rate of 200 Hz. Accordingly, the treatment time of around 10-15 second per irradiated point is required.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA126  
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SUSPSIK120
 Spatial Distributions of natU(n, f), 238U(n, g) Reaction Rates in Spallation Neutron Fields Produced by Deuterons and 12C Ions on the Massive Uranium Target  
THPVA129   use link to access more material from this paper's primary paper code  
 
  • A. Zhadan, V.V. Sotnikov, V.A. Voronko
    NSC/KIPT, Kharkov, Ukraine
  • S.I. Tyutyunnikov
    JINR, Dubna, Moscow Region, Russia
  • P. Zhivkov
    INRNE, Sofia, Bulgaria
  
  The results of the experiments carried out within the framework of Energy and Transmutation of RAW at JINR NUCLOTRON accelerator are presented. The target assembly QUINTA consisting of 512 kg natural uranium was irradiated by deuteron and carbon beams with energies 1, 2, 4 and 8 GeV (deuterons), 24 and 48 GeV (carbon). Spatial distribution and total number of capture reaction and fission reaction rates was obtained using the activation technique. The integral number of fissions reactions in the volume of uranium target remains approximately constant within our statistical errors for 1, 2, 4 and 8 GeV deuteron beams and for 24 and 48 GeV carbon beams (per one primary particle and per 1 GeV of beam energy). For the integral number of capture reactions with deuteron beams we have seen maximum at 2 GeV. Some of the obtained experimental data was analyzed using the MCNPX transport code. For spatial distribution of reaction rates in case of 4 and 8 GeV deuteron beams we have seen a discrepancy between the experimental and calculated values in backward direction.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA129  
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SUSPSIK121
 Development of a 3.95 Mev X-Band Linac-Driven X-Ray Combined Neutron Source  
THPVA098   use link to access more material from this paper's primary paper code  
 
  • J.M. Bereder, K. Dobashi, Y. Mitsuya, M. Uesaka
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
  • M. Ishida, Y. Ohshima
    PWRI, Ibaraki, Japan
  • J. Kusano
    Accuthera Inc., Kawasaki, Kanagawa, Japan
  • Y. Takahashi
    The University of Tokyo, Tokyo, Japan
  • Y. Tanaka
    The University of Tokyo, Institute of Industrial Science, Tokyo, Japan
  
  Funding: Council for Science, Technology and Innovation (CSTI), Cross-Ministrial Strategic Innovation Promo-tion Program (SIP), Japan Science and Technoogy Agency (JST)
The existing non-destructive inspection method employed for concrete structures uses high energy X-rays to detect internal flaws in concrete structures and iron reinforcing rods. In addition to this conventional method, the authors are developing an innovative inspection system that uses a mobile compact linac-driven neutron source that utilizes neutron backscattering, to measure the moisture content in concrete structures and estimate the corrosion probability distribution of iron reinforcing rods. By combining the knowledge of the moisture distribution in concrete structures with the information of its inner structure, the remaining life of concrete structures can be estimated. Further experiments will be conducted in the laboratory, and the moisture detection experiment in the real bridge is scheduled for 2017. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA098  
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SUSPSIK122
 Non-Destructive Measurement of Electron Microbunch Separation  
THPVA141   use link to access more material from this paper's primary paper code  
 
  • H. Zhang, G. Doucas, H. Harrison, I.V. Konoplev, A.J. Lancaster
    JAI, Oxford, United Kingdom
  • A. Aryshev, M. Shevelev, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
  
  With the development of femtosecond lasers, the generation of micro-bunched beams directly from a photocathode becomes routine; however, the monitoring of the separation is still a challenge. We present the results of proof-of-principle experiments measuring the distance between two bunches via the amplitude modulation analysis of a monochromatic radiation signal. Good agreement with theoretical prediction is shown.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-THPVA141  
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SUSPSIK123
 A Novel Dual-Mode Dual-Frequency Linac Design  
TUPAB132   use link to access more material from this paper's primary paper code  
 
  • M.H. Nasr, S.G. Tantawi
    SLAC, Menlo Park, California, USA
  
  In this paper we will present a new type of accelerator structure that operates simultaneously at two accelerating modes with two frequencies. The frequencies are not harmonically related, but rather have a common sub-harmonic. This design will use a recently developed parallel-feeding network that feeds every cavity cell independently using a distributed feeding network. This will overcome many of the practical complications of coupled cell structure. We will provide the theoretical background for our dual-mode design as well as present our optimized design that operates at C and X bands simultaneously and provides enhanced gradient and efficiency compared to single-mode designs.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2017-TUPAB132  
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