SUPSS —  Special Student Poster Session   (08-May-16   14:00—18:00)
Paper Title Page
SUPSS001
 Experimental Demonstration of β* Leveling at the LHC  
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  • A.A. Gorzawski, D. Mirarchi, B. Salvachua, J. Wenninger
    CERN, Geneva, Switzerland
  
  The HL-LHC project foresees to boost the LHC peak luminosity beyond the capabilities of the LHC experimental detectors. Leveling the luminosity down to a constant value that is sustainable for the experiments is therefore the operational baseline of HL-LHC. Various luminosity leveling techniques are available at the LHC. Leveling by adjusting β*, the betatron function at the interaction point, to maintain a constant luminosity is favorable because the beams remain head-on which provides optimal stability from the point of view of collective effects. Smooth leveling by β* requires however excellent control of the beam orbits and beam losses in the interaction regions since the beam offsets should not vary by more than around one r.m.s. beam size during the process. This leveling scheme has been successfully tested and experimentally demonstrated during the LHC machine development program in 2015. This paper presents results on luminosity leveling over a β* range from 10 m to 0.8 m and provides an outlook on future developments and use of this technique at the LHC.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW013  
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SUPSS002
 Simulating Proton Synchrotron Radiation in the Arcs of the LHC, HL-LHC and FCC-hh  
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  • G. Guillermo Cantón, F. Zimmermann
    CERN, Geneva, Switzerland
  • D. Sagan
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  At high proton-beam energies, beam-induced synchrotron radiation is an important source of heating, of beam-related vacuum pressure increase, and of primary photoelectrons, which can give rise to an electron cloud. We use the Synrad3D code developed at Cornell to simulate the photon distributions in the arcs of the LHC, HL-LHC, and FCC-hh. Specifically, for the LHC we study the effect of the "sawtooth" chamber, for the HL-LHC the consequences of the ATS optics with large beta beating in the arcs, and for the FCC-hh the effect of a novel beam-screen design, with a long slit surrounded by a "folded" ante-chamber.  
slides icon Slides SUPSS002 [0.329 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOCA03  
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SUPSS003
 Radiation Load Optimization in the Final Focus System of FCC-hh  
TUPMW018   use link to access more material from this paper's primary paper code  
 
  • R. Martin, M.I. Besana, F. Cerutti, R. Tomás
    CERN, Geneva, Switzerland
  
  With a center-of-mass energy of up to 100 TeV, FCC-hh will produce highly energetic collision debris at the Interaction Point (IP). Protecting the final focus quadrupoles from this radiation is challenging, since the required amount of shielding placed inside the magnets will reduce the free aperture, thereby limiting the β* reach and luminosity. Hence, radiation mitigation strategies that make best use of the available aperture are required. In this paper, we study the possibility to split the first quadrupole Q1 into two quadrupoles with individual apertures, in order to distribute the radiation load more evenly and reduce the peak dose.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW018  
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SUPSS004
 Modelling and Measurements of Bunch Profiles at the LHC Flat Bottom  
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  • S. Papadopoulou, F. Antoniou, J.E. Muller, Y. Papaphilippou, G. Trad
    CERN, Geneva, Switzerland
  
  At the LHC flat bottom the interplay between a series of effects (i.e. intrabeam scattering, longitudinal beam manipulations, non-linearities of the machine, etc) can lead to a population of the tails of the beam distributions, which may become non-Gaussian. This paper presents observations of the evolution of particle distributions in the LHC flat bottom. Novel distribution functions are employed to represent the beam profiles, and used as a guideline for generalising emittance growth rate estimations due to IBS. Finally, an attempt is made to benchmark an IBS Monte-Carlo simulation code, able to track 3D particle distributions, with the measured beam profile evolutions.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW022  
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SUPSS005
 Machine Protection from Fast Crab Cavity Failures in the High Luminosity LHC  
TUPMW025   use link to access more material from this paper's primary paper code  
 
  • A. Santamaría García, R. Bruce, H. Burkhardt, F. Cerutti, R. Kwee-Hinzmann, A. Lechner, K.N. Sjobak, A. Tsinganis
    CERN, Geneva, Switzerland
  • R. Kwee-Hinzmann
    Royal Holloway, University of London, Surrey, United Kingdom
  
  The time constant of a crab cavity (CC) failure can be faster than the reaction time of the active protection system. In such a scenario, the beams cannot be immediately extracted, making the the protection of the machine rely on the passive protection devices. At the same time, the energy stored in the High Luminosity (HL) LHC beams will be doubled with respect to the LHC to more than 700 MJ, which increases the risk of damaging the machine and the experiments in a failure scenario. In this study we estimate the impact that different CC failures have on the collimation system. We also give a first quantitative estimate of the effect of these failures on the elements near the experiments based on FLUKA simulations, using an updated HL-LHC baseline.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMW025  
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SUPSS007
 Towards a Mono-chromatization Scheme for Direct Higgs Production at FCC-ee  
WEPMW009   use link to access more material from this paper's primary paper code  
 
  • M.A. Valdivia García, F. Zimmermann
    CERN, Geneva, Switzerland
  • A. Faus-Golfe
    IFIC, Valencia, Spain
  
  Direct Higgs production in e+e− collisions at the FCC is of interest if the centre-of-mass energy spread can be reduced by at least an order of magnitude. A mono-chromatization scheme, to accomplish this, can be realized with horizontal dispersion of opposite sign for the two colliding beams at the interaction point (IP). We review approaches from historical mono-chromatization studies, then derive a set of IP parameters which would provide the required performance in FCC e+e− collisions at 63 GeV beam energy, compare these with the baseline optics parameters at neighbouring energies (45.6 and 80 GeV), comment on the effect of beamstrahlung, and, finally, discuss the modifications of the FCC-ee final-focus optics needed to obtain the required parameters.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW009  
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SUPSS008
 Simulation of Heavy-Ion Beam Losses with the SixTrack-FLUKA Active Coupling  
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  • P.D. Hermes, R. Bruce, F. Cerutti, A. Ferrari, J.M. Jowett, A. Lechner, A. Mereghetti, D. Mirarchi, P.G. Ortega, S. Redaelli, B. Salvachua, E. Skordis, G. Valentino, V. Vlachoudis
    CERN, Geneva, Switzerland
  
  Funding: Work suppported by the Wolfgang Gentner Programme of the German BMBF
The LHC heavy-ion program aims to further increase the stored ion beam energy, putting high demands on the LHC collimation system. Accurate simulations of the ion collimation efficiency are crucial to validate the feasibility of new proposed configurations and beam parameters. In this paper we present a generalized framework of the SixTrack-FLUKA coupling to simulate the fragmentation of heavy-ions in the collimators and their motion in the LHC lattice. We compare heavy-ion loss maps simulated on the basis of this framework with the loss distributions measured during heavy-ion operation in 2011 and 2015. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMW029  
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SUPSS009
 Properties of Synchrotron Radiation from Segmented Undulators based on a Wigner Distribution Function  
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  • H.W. Luo, C.H. Lee
    NTHU, Hsinchu, Taiwan
  • T.Y. Chung, C.-S. Hwang
    NSRRC, Hsinchu, Taiwan
  
  Three long straight sections with a double mini-βy lattice were designed in Taiwan Photon Source. For the purpose to understand whether the brilliance can be enhanced or not when two collinear undulators were installed in the double mini-βy. Therefore, the Wigner distribution function (WDF) is developed to calculate the brilliance in the double mini-βy lattice that is a natural way to describe a synchrotron radiation source. Herein, the brilliance is thereby calculable without a Gaussian approximation used in a conventional manner. Some important optical properties such as the degree of coherence can be directly calculated with this method. We use it as an example to investigate the properties of radiation from a segmented undulator.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW042  
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SUPSS010
 Influence of Filling Pattern Structure on Synchrotron Radiation Spectrum at ANKA  
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  • J.L. Steinmann, E. Blomley, M. Brosi, E. Bründermann, C.M. Caselle, N. Hiller, B. Kehrer, A.-S. Müller, M. Schedler, M. Schuh, M. Schwarz, P. Schönfeldt, M. Siegel
    KIT, Karlsruhe, Germany
  
  Funding: This work is supported by the Helmholtz International School for Teratronics (HIRST)
We present the effects of the filling pattern structure in multi-bunch mode on the beam spectrum. This effects can be seen by all detectors whose resolution is better than the RF frequency, ranging from stripline and Schottky measurements to high resolution synchrotron radiation measurements. Our heterodyne measurements of the emitted coherent synchrotron radiation at 270 GHz reveal discrete frequency harmonics around the 100 000th revolution harmonic of ANKA, the synchrotron radiation facility in Karlsruhe, Germany. Significant effects of bunch spacing, gaps between bunch trains and variations in individual bunch currents on the emitted CSR spectrum are described by theory and supported by observations. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOW015  
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SUPSS011
 Preliminary Study for the HLS Variable Pulse Length Storage Ring by Two Harmonic Cavities  
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  • T. Zhang, W. Li, L. Shang, L. Wang, C.-F. Wu
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  The 4th harmonic cavity is successfully used in HLS II to increase the beam lifetime and suppress the beam instability now. At the future, a scheme of the two higher harmonic cavities may be applied in Hefei light source for a variable electron pulse length storage ring (HLS VSR). With optimal RF system parameters, 45 ps long bunches and 6 ps short bunches may be stored simultaneously in the HLS storage ring. The ratio of the bunch number for 45 ps to the one for 6 ps is 1:2. Particle tracking calculations are performed to simulate the longitudinal phase space of the new system and to track the process of shortening bunches with Elegant Software. Moreover, a tracking simulation code for RF systems is developed in MALAB to study transient beam loading which affects bunch length, phase stability, and longitudinal muti-bunch oscillation for different fill patterns. In the end, the preliminary design of the two harmonic cavities for longitudinal bunch focusing is given.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR058  
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SUPSS013
 The Soft X-ray Self-seeding System Design for SXFEL User Facility  
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  • K.Q. Zhang, T. Liu, D. Wang
    SINAP, Shanghai, People's Republic of China
  • Y. Feng
    SLAC, Menlo Park, California, USA
  
  X-ray free electron laser driven by SASE probes the evolution of the new generation light source in high brightness, transverse coherence. However, since SASE achieves lasing from random shotnoise, Poor longitudinal coherence and relative wide bandwidth of SASE FEL limit the operation of many type experiments. Self-seeding as a promising scheme produces longitudinal coherence and even narrower bandwidth radiation by a monochromatic seeding instead of external seeding. The self-seeding system design based on the grating monochromator is carried out for SXFEL user facility across the photon energy from 800-1200 eV. The grating monochromator with a resolution power of 〖10〗-4 can provide a monochromatic seeding pulse to the seeding undulator. The layout design and simulations of the scheme are presented. It is showing that the self-seeding system for SXFEL user facility is able to improve SASE FEL longitudinal coherence significantly.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOW029  
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SUPSS014
 Optimization of Electron Beam Properties for Generation of Coherent THz Undulator Radiation at PBP-CMU Linac Laboratory  
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  • N. Chaisueb, S. Rimjaem, J. Saisut, C. Thongbai
    Chiang Mai University, Chiang Mai, Thailand
  
  Funding: This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Material Science, Chiang Mai University, and the Science Achievement Scholarship of Thailand.
Relativistic femtosecond electron bunches produced from the linear accelerator at the Plasma and Beam (PBP) Physics Research Facility are currently used to generate THz radiation via transition radiation. An upgrade to increase the intensity of the THz radiation by using a coherent undulator radiation method is conducted. Optimizations, measurements and analysis of the electron beam properties, which include current, energy and energy spread as well as electron bunch length, are performed to investigate the capability of electron beam production from the current accelerator system. This is also to estimate the possibility to produce the coherent undulator radiation of the PBP-CMU linac. Expected characteristics of the coherent undulator radiation are studied and reported in this contribution.
The authors would like to acknowledge the financial support to participate this conference by the Department of Physics and Material Science and the Graduate School, Chiang Mai University. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW026  
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SUPSS015
 Compact Standing Wave Electron Linac with the Hybrid Accelerating and Power Generation Cell  
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  • E.A. Savin, S.V. Matsievskiy, N.P. Sobenin, I.D. Sokolov
    MEPhI, Moscow, Russia
  • A.A. Zavadtsev
    Nano, Moscow, Russia
  
  Compact electron linear accelerators for small energies are now found their place in the industrial market. Such accelerators are used for cancer treatment, cargo inspection, when one needs higher dose that X-ray source can produce, food and medicaments irradiation etc. Acceleration structures themselves are already developed very well, so the most important issue now ' is to make the whole installation with power supply, RF tracts, cooling system ' as smaller as possible to provide the structure mobility. In this article we present the development how to combine a power supply (usually it is a klystron, IOT, magnetron or solid state amplifier) with the accelerating cell itself, that can decrease installation size at least twice. No RF tracts needed, no reflected power will occur, so no circulator needed. Different power input combinations have been studied, but the smallest and the most efficient one has been manufactured for cold tests at S-band frequency range. In this structure it is very easy to vary accelerating voltage simply changing the generator beam current or the generator beam accelerating voltage.

 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW024  
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SUPSS016
 Tunable High-Intensity Electron Bunch Train Production Based on Nonlinear Longitudinal Space Charge Oscillation  
TUPOW018   use link to access more material from this paper's primary paper code  
 
  • Z. Zhang, H.B. Chen, Y.-C. Du, W.-H. Huang, J. Shi, X.L. Su, C.-X. Tang, Q.L. Tian, D. Wang, W. Wang, L.X. Yan, L.M. Zheng, Z. Zhou
    TUB, Beijing, People's Republic of China
  • W. Gai
    ANL, Argonne, Illinois, USA
  
  High peak current electron bunch trains with tunable terahertz (THz) spacing are produced and measured experimentally. An initial picosecond periodic modulation in the temporal profile of a relativistic electron beam is magnified by the longitudinal space charge forces. As opposed to trying to reduce its smearing effect for large beam current, we take advantages of the nonlinear space charge oscillation through controlling the plasma phase advance. The spacing of the bunch train can be varied continuously either by tuning the velocity bunching of a radio-frequency gun or by tuning the compression of a downstream magnetic chicane. The narrow-band μJ-level THz radiation from the bunch train are also measured with tunable central frequency of the spectral from ~0.5 THz to 1.6 THz. The bunch train measurements are consistent with the particle tracking simulations.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW018  
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SUPSS017
 Electron Beam Dynamics Studies for ELI-NP GBS Linac  
TUPOW043   use link to access more material from this paper's primary paper code  
 
  • A. Giribono, F. Cardelli, L. Palumbo, L. Piersanti
    University of Rome La Sapienza, Rome, Italy
  • D. Alesini, A. Gallo, C. Vaccarezza, A. Vannozzi
    INFN/LNF, Frascati (Roma), Italy
  • A. Bacci, C. Curatolo, I. Drebot, V. Petrillo, A.R. Rossi, L. Serafini
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • G. Campogiani
    Rome University La Sapienza, Roma, Italy
  • F. Cardelli, L. Piersanti
    INFN-Roma1, Rome, Italy
  • L. Palumbo
    INFN-Roma, Roma, Italy
  
  The ELI-NP Gamma Beam System is an advanced gamma ray source based on the Compton back-scattering effect with unprecedented specifications of brilliance ( >1021), monochromaticity (0.5%) and energy tunability (0.2 - 19.5 MeV), presently under construction in Magurele-Bucharest (RO). Here the head-on collision is foreseen between an intense high power laser beam and a high brightness high quality electron beam with a maximum kinetic energy of 740 MeV. The electron beam dynamics analysis and control for the ELI-NP GBS Linac in the single and multi bunch mode have been investigated and are here illustrated.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW043  
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SUPSS018
 LLNL Laser-Compton X-ray Characterization  
TUPOW052   use link to access more material from this paper's primary paper code  
 
  • Y. Hwang, T. Tajima
    UCI, Irvine, California, USA
  • G.G. Anderson, C.P.J. Barty, D.J. Gibson, R.A. Marsh
    LLNL, Livermore, California, USA
  
  Funding: This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344
Laser-Compton X-rays have been produced at LLNL, and results agree very well with modeling predictions. An X-ray CCD camera and image plates were calibrated and used to characterize the 30 keV X-ray beam. A resolution test pattern was imaged to measure the source size. K-edge absorption images using thin foils confirm the narrow bandwidth of the source and offer electron beam diagnostics. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW052  
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SUPSS019
 Optimization of Electron Beam and Laser Pulse Alignment and Focusing at Interaction Point for a Compact FEL Based Inverse-Compton Scattering X-Ray Source  
TUPOW051   use link to access more material from this paper's primary paper code  
 
  • P. Niknejadi, J. Madey
    University of Hawaii, Honolulu,, USA
  
  Funding: This work was funded under the Department of Homeland Security Grant No. 2010-DN-077-ARI045.
In July 2015, the first beam of 10 keV X-rays from our FEL based inverse-Compton scattering X-ray source was detected.* In this setup, 3 micron laser pulses at 2.856 GHz repetition rate from a free electron laser are collided head-on with 40 MeV electron bunches driving the laser. To attain our objective the ebeam was required to have 1) a tight focus at the X-ray interaction point, 2) vertical and horizontal envelopes matched to the downstream undulator, 3) minimized transverse dimensions for low ionizing radiation. Optimization of these quantities required information on the evolution of the beam profiles between the beam spot images on the available insertable screens, leading to the need for a simulator to accurately trace the beam profiles through the system. A simulator was developed and used to optimize the system Twiss parameters by comparing the effectiveness of the beam profiles computed by fitting the profiles to the observed beam spot images along the beamline for different cathode positions. This method proved to be considerably more flexible and effective than the more traditional quadrupole scan technique. Summery of the designed system and results are provided.
* John M. J. Madey, ARI final report, December 2015. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOW051  
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SUPSS020
 Generation of Homogeneous and Patterned Electron Beams using a Microlens Array Laser-Shaping Technique  
THPOW021   use link to access more material from this paper's primary paper code  
 
  • A. Halavanau, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • D.R. Edstrom, P. Piot, J. Ruan, J.K. Santucci
    Fermilab, Batavia, Illinois, USA
  • W. Gai, G. Ha, J.G. Power, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • G. Ha
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • G. Qiang
    TUB, Beijing, People's Republic of China
  
  Funding: Northern Illinois University - US DOE contract No. DE-SC0011831. Fermilab - US DOE contract No. DE-AC02-07CH11359. The Argonne wakefield facility - US DOE contract No. DE-AC02-06CH11357.
In photocathodes the achievable electron-beam parameters are controlled by the laser used to trigger the photoemission process. Non-ideal laser distribution hampers the final beam quality. Laser inhomogeneities, for instance, can be "amplified" by space-charge force and result in fragmented electron beams. To overcome this limitation laser shaping methods are routinely employed. In the present paper we demonstrate the use of simple microlens arrays to dramatically improve the transverse uniformity. We also show that this arrangement can be used to produce transversely-patterned electron beams. Our experiments are carried out at the Argonne Wakefield Accelerator facility. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW021  
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SUPSS021
 Intrinsic Emittance Reduction in Transmission Mode Photocathodes  
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  • H. Lee, I.V. Bazarov, L. Cultrera
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  High quantum efficiency (QE) and low emittance electron beams provided by multi-alkali photocathodes make them of great interest for next generation high brightness photoinjectors. Spicer's three-step model well describe the photoemission process, however, some photocathode characteristics such as their thickness have not been completely exploited to further improve the brightness of the generated electron beam. In this work, we report on the emittance and QE of a multi-alkali photocathode grown onto glass substrate operated in transmission and reflection modes at different photon energies. We observed a 20% reduction on the intrinsic emittance from the reflection to the transmission mode operation. This observation can be explained by inelastic electron-phonon scattering events experienced by electrons during their transit towards the cathode surface. This scattering will expect the further emittance reduction than the no scattering at the cryo-temperatures.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW023  
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SUPSS022
 A Study of CsK2Sb Multi-alkali Photocathode by Ultraviolet Photoelectron Spectroscopy at UVSOR  
THPOW005   use link to access more material from this paper's primary paper code  
 
  • M. Urano, M. Kuriki, K. Negishi
    HU/AdSM, Higashi-Hiroshima, Japan
  • T. Konomi, Y. Seimiya, N. Yamamoto
    KEK, Ibaraki, Japan
  
  Photocathode is one of the most important components in the next-generation accelerators, especially based on linear accelerators. Photocathode performance depends not only on electronic state in its bulk material but also on the surface condition. CsK2Sb multi-alkali photocathode is a candidate for the high brightness electron source because of its high quantum efficiency by green laser and its high robustness. We have carried out an UPS (UV Photoelectron Spectroscopy) experiment at UVSOR facility, synchrotron radiation light source in Aichi Japan. We have compared the UPS spectra among several samples, each one has a different quantum efficiency, and try to find physics which decide photocathode's performance. In this case, we focused some characters correlated to the quantum efficiency. I'm going to present a result of this analysis.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW005  
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SUPSS023
 Cumulative Damage of Ultrafast Laser Pulses  
THPOW054   use link to access more material from this paper's primary paper code  
 
  • A. Hanuka, L. Schächter
    Technion, Haifa, Israel
  • R.J. England, I.V. Makasyuk, K. Soong, K.P. Wootton, Z. Wu
    SLAC, Menlo Park, California, USA
  
  We demonstrate experimentally that damage threshold fluence (DTF) for fused silica changes with the number of femtosecond laser (10Hz 600Hz, 655 fs, 800nm) shots. Based on the experimental data we were able to develop a model which indicates that the change in DTF varies with number of shots logarithmically (lnp) up to a critical value. Above this value, DTF approaches an asymptotic value. Both DTF for a single shot and the asymptotic value as well as the critical value where this happens are extrinsic parameters dependent on the configuration (repetition rate, pressure and geometry near or at the surface). Indications are that the power of this dependence (p) is an intrinsic parameter independent of the configuration.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW054  
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SUPSS024
 Fiber Laser Development for Dielectric Laser-driven Accelerator and Electron Beam Source  
THPOW056   use link to access more material from this paper's primary paper code  
 
  • H. Okamoto, S. Otsuki
    The University of Tokyo, Tokyo, Japan
  • K. Koyama, M. Uesaka
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
  • D. Satoh, T. Shibuya
    TIT, Tokyo, Japan
  • M. Yoshida
    KEK, Ibaraki, Japan
  
  Our group is aiming for developing a table-top electronμbeam source, whose beam size is micro-meter order so that we can irradiate just the nuclei of cells (1μm) and observe the behavior in real time. This beam source will be realized by dielectric laser-driven accelerators(DLAs), which is expected to produce acceleration gradients of ~GV/m. To drive these accelerators, ultra-short pulse laser has to be incident to the structure*. We chose Ytterbium (Yb) fiber laser for generating and amplifying ultra-short laser pulse, which has high quantum efficiency and can easily pumped by LD, and is proper to produce ultra-short pulses because of its wide-band oscillation. We succeeded in getting ultra-short pulse (central wavelength: {1030} nm, average output: 10 W, pulse duration: ~10 ps, reputation rate: 84 MHz) from Yb fiber laser system. Also in order to make electron bunch by photo cathode, we then converted the obtained IR laser to UV of 258 nm (4ω) using BBO and LBO crystals. We are planning to amplify the pulses by Yb:YAG in future, which has its amplification band in {1030} nm.
* K. Koyama el al., "Design Of Photonic Crystal Accelerator For Radiation Biology," IPAC'12 Proceedings (2014) 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOW056  
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SUPSS025
 Simulated Measurements of Cooling in Muon Ionization Cooling Experiment  
TUPMY011   use link to access more material from this paper's primary paper code  
 
  • T.A. Mohayai
    IIT, Chicago, Illinois, USA
  • C.T. Rogers
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • P. Snopok
    Fermilab, Batavia, Illinois, USA
  • P. Snopok
    Illinois Institute of Technology, Chicago, Illlinois, USA
  
  Cooled muon beams set the basis for the exploration of physics of flavour at a Neutrino Factory and for multi-TeV collisions at a Muon Collider. The international Muon Ionization Cooling Experiment (MICE) measures beam emittance before and after an ionization cooling cell and aims to demonstrate emittance reduction in muon beams. In the current MICE Step IV configuration, the MICE muon beam passes through low-Z absorber material for reducing its transverse emittance through ionization energy loss. Two scintillating fiber tracking detectors, housed in spectrometer solenoid modules upstream and downstream of the absorber are used for reconstructing position and momentum of individual muons for calculating transverse emittance reduction. However, due to existence of non-linear effects in beam optics, transverse emittance growth can be observed. Therefore, it is crucial to develop algorithms that are insensitive to this apparent emittance growth. We describe a different figure of merit for measuring muon cooling which is the direct measurement of the phase space density.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY011  
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SUPSS027
 Recent Progress of Proton Acceleration at Peking University  
TUPMY018   use link to access more material from this paper's primary paper code  
 
  • Q. Liao, Y.X. Geng, C. Lin, H.Y. Lu, W.J. Ma, X.Q. Yan, Y.Y. Zhao
    PKU, Beijing, People's Republic of China
  
  We study the enhanced laser ion acceleration using near critical density plasma lens attached to the front of a solid target. The laser quality is spontaneously improved by the plasma lens and energy density of hot electrons is greatly increased by the direct laser acceleration mechanism. Both factors will induce stronger sheath electric field at the rear surface of the target, which accelerates ions to a higher energy. Particle-in-cell simulations show that proton energy can be increased 2-3 times compared with single solid target. This result provides the opportunities for applications of laser plasma accelerator, such as cancer therapy. Further experiments will soon be carried out on 200 TW laser acceleration system at Peking University.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY018  
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SUPSS028
 CLAPA Proton Beam Line in Peking University  
TUPMY019   use link to access more material from this paper's primary paper code  
 
  • J.G. Zhu, J.E. Chen, C. Lin, H.Y. Lu, W.J. Ma, L. Tao, X.Q. Yan, K. Zhu
    PKU, Beijing, People's Republic of China
  
  Comparing with the conventional accelerator, the laser plasma accelerator can accelerate ions more effectively and greatly reduce the scale and cost. A laser accelerator− Compact Laser Plasma Accelerator (CLAPA) is being built at Institute of Heavy Ion physics of Peking University. According to the beam parameters from proof of principle experiments and theoretical simulations, we design the beam line for ions transport which is being built now and in the near future we will carry out experimental study with it. The beam line is mainly constituted by quadrupole and analyzing magnets . The quadrupole triplet lens collects protons generated from the target, while the analyzing magnet system will choose the protons with proper energy. The transport is simulated by program TRACK. The beam line is designed to deliver proton beam with the energy of 1~ 40MeV, energy spread of ±1% and 106-8 protons per pulse to satisfy the requirement of different experiments. The transmission efficiency is about 94% when the energy spread is ±1%.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY019  
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SUPSS029
 Drive Generation and Propagation Studies for the Two Beam Acceleration Experiment at the Argonne Wakefield Accelerator  
TUPMY036   use link to access more material from this paper's primary paper code  
 
  • N.R. Neveu, M.E. Conde, D.S. Doran, W. Gai, G. Ha, C.-J. Jing, W. Liu, J.G. Power, D. Wang, C. Whiteford, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • S.P. Antipov, C.-J. Jing
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • G. Ha
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • N.R. Neveu
    IIT, Chicago, Illinois, USA
  • D. Wang
    TUB, Beijing, People's Republic of China
  
  Funding: Work supported by by the U.S. Department of Energy under contract No. DE-AC02-06CH11357.
Simplified staging in a two beam accelerator (TBA) has been accomplished at the Argonne Wakefield Accelerator (AWA) facility. This layout consists of a drive beamline and witness beamline operating synchronously. The drive photoinjector linac produces a 70 MeV drive bunch train of eight electron bunches (charge per bunch between 5-40 nC) that pass through decelerating structures in each TBA stage. The witness linac produces an 8 MeV witness bunch that passes through the accelerating structures in each TBA stage. Recent effort has been focused on improving the uniformity of the UV laser pulses that generate the bunch trains. Current work at the AWA is focused on the transition from simplified staging to full staging. A kicker will be designed and installed to direct bunch trains to one TBA stage only. Preliminary calculations and simulation results are presented. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMY036  
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SUPSS031
 Development of RF System for Measuring Plasma Density Modulation of Proton Beam-driven Plasma Wakefield  
WEPMY016   use link to access more material from this paper's primary paper code  
 
  • S.Y. Kim, M. Chung
    UNIST, Ulsan, Republic of Korea
  
  Proton beam-driven plasma wakefield acceleration technique using the proton beam of Super Proton Syn-chrotron (SPS) at CERN has been actively researched these days. Plasma density modulation due to the proton beam will generate high-gradient's electric field within the modulated plasma. The key role is Self-Modulation Instability (SMI) of the long proton beam. To understand SMI phenomena, we have studied RF system such as heterodyne system for measuring modulated plasma den-sity caused by the SMI. In this work, we design the details of the RF system and optical system of focusing millimetre-sized electromagnetic wave using CODE V and plasma-electromagnetic wave interactions using simulation tools.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY016  
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SUPSS032
 Homogeneous Focusing of Train of Short Relativistic Electron Bunches by Plasma Wakefield  
WEPMY022   use link to access more material from this paper's primary paper code  
 
  • V.I. Maslov, I.N. Onishchenko
    NSC/KIPT, Kharkov, Ukraine
  • I.P. Levchuk (Yarovaya)presenter
    KhNU, Kharkov, Ukraine
  
  The focusing of bunches by wakefield, excited in plasma by resonant sequence of relativistic electron bunches (repetition frequency of the bunches coincides with the plasma frequency), is inhomogeneous. In this paper we investigate wakefield plasma lens, in which all bunches of sequence are focused identically and uniformly, for short relativistic electron bunches. For this it is necessary that the charge of 1-st bunch is smaller in determined times than the charges of the other bunches, the interval between back front of 1-st bunch and 1-st front of 2-nd bunch equals determined value, the interval between back front of N-th bunch and 1-st front of (N+1)-th bunch for all other bunches is multiple to excited wavelength. It is shown that only 1-st bunch is in finite Ez≠0. Other bunches are in zero longitudinal electrical wakefield. Hence the 1-st bunch interchange by energy with wakefield. The subsequent bunches don't interchange by energy with wakefield and the amplitude of wakefield doesn't change along sequence. Radial wake force Fr in regions, occupied by bunches, is approximately constant along bunches.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY022  
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SUPSS033
 Compact Laser Plasma Accelerator at Peking University  
WEPMY011   use link to access more material from this paper's primary paper code  
 
  • L.R.F. Li, J.E. Chen, S.C. Gao, Y.X. Geng, Q. Liao, J B. Liu, H.Y. Lu, X.Q. Yan, Y.Y. Zhao, Y.Y. Zhu
    PKU, Beijing, People's Republic of China
  • Y.R. Shou
    Peking University, School of Physics, Beijing, People's Republic of China
  
  A brand new and solely accelerator based on the interaction physics of high intensity ultrafast laser and plasmas, named Compact LAser Plasma Accelerator (CLAPA), was recently built. The laser system can deliver 5J/25fs @ 800nm pulses with contrast of 10-10. Experiments on electron acceleration is scheduled with the regime of laser wakefield acceleration. The charge and the energy spread of the accelerated electron beams will be concerned mainly. The experiments is planned with gas targets with single and dual stages. For the single stage acceleration, we will try density ramp injection and a loose focusing for a monoenergetic electron beam with more charge for some applications. With the PIC simulations and new injection methods, it is expected to generate GeV/tens pC electron beam with an energy spread of <1%. For the two stage cascaded acceleration, we will focus on the staged acceleration and control of the injection of the second stage, as well as the acceleration length of the second stage by manipulating the parameters of the gas target as well as the laser itself. The far future goal of the second plan is to develop a designable and applicable accelerators.
* W.Lu, Phys. Rev.ST Accel. Beams 10.061301 （2007）
** J. Faure, Nature 431, 541 (2004)
***J.S. Liu, Phys. Rev. Lett 107, 035001 (2011)
 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY011  
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SUPSS034
 Transverse Tolerances of a Multi-Stage Plasma Wakefield Accelerator  
WEPMY009   use link to access more material from this paper's primary paper code  
 
  • C.A. Lindstrøm, E. Adli, J. Pfingstner
    University of Oslo, Oslo, Norway
  • E. Marín, D. Schulte
    CERN, Geneva, Switzerland
  
  Funding: This work is supported by the Research Council of Norway.
Plasma wakefield acceleration (PWFA) provides GeV/m-scale accelerating fields, ideal for applications such as a future linear collider. However, strong focusing fields imply that a transversely offset beam with an energy spread will experience emittance growth from the energy dependent betatron oscillation. We develop an analytic model for estimating tolerances from this effect, as well as an effective simplified simulation tool in Elegant. Estimations for a proposed 1 TeV PWFA linear collider scheme indicate tight tolerances of order 40 nm and 1 μrad in position and angle respectively. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY009  
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SUPSS035
 Numerical Studies of Self Modulation Instability in the Beam-driven Plasma Wakefield Experiments  
WEPMY017   use link to access more material from this paper's primary paper code  
 
  • K. Moon, M. Chung
    UNIST, Ulsan, Republic of Korea
  
  Proton beam-driven plasma wakefield acceleration was recently proposed as a way to bring electrons to TeV energy range in a single plasma section. When the ultra-relativistic long proton beam propagates into the plasmas, this bunch splits into many small bunches. This phenomenon is known as a Self-Modulation Instability (SMI), and its characteristics depend on the ratio of bunch length and plasma wavelength. In this study, we first introduce a Particle-In-Cell (PIC) code WARP, focusing on the basis of parallel version structure. Through numerical simulations using the WARP, we investigate the characteristics of the SMI and propose possible experimental setup at the Injector Test Facility (ITF) of Pohang Accelerator Laboratory (PAL). Also, we present dependencies of the witness beam quality on both the driver beam and plasma parameters.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY017  
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SUPSS037
 Laser Ablation Ion Source for Highly Charge-State Ion Beams  
WEPMY036   use link to access more material from this paper's primary paper code  
 
  • N. Munemoto, K. Horioka
    TIT, Yokohama, Japan
  • K. Okamura, S. Takano, K. Takayama
    KEK, Ibaraki, Japan
  • K. Okamura, K. Takayama
    Sokendai, Ibaraki, Japan
  
  The KEK Laser ablation ion source (KEK-LAIS) is un-der development in order to generate highly ionized metal and fully ionized carbon ions for future applica-tions*. Laser ablation experiments have been carried out by using Nd-YAG laser (0.75 J/pulse, 20 ns) at the KEK test bench. Basic parameters such as a charge-state spec-trum and momentum spectrum of the plasma and extract-ed ion beam current have been obtained. Extraction of C ions from the LAIS is described.
* N.Munemoto et al., Rev. Sci. Inst. 85, 02B922 (2014)
 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY036  
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SUPSS038
 Photoemission Properties of LaB6 and CeB6 Under Various Temperature and Incident Photon Energy Conditions  
WEOAB03   use link to access more material from this paper's primary paper code  
 
  • K. Morita, T. Katsurayama, T. Kii, K. Masuda, T. Murata, K. Nagasaki, T. Nogi, H. Ohgaki, S. Suphakul, K. Torgasin, H. Yamashita, H. Zen
    Kyoto University, Kyoto, Japan
  
  Recently, thermionic cathode materials such as LaB6, Ir5Ce and dispenser cathodes have been also used as photocathode since they have low work function, reasonably high quantum efficiency, and long lifetime*,**. However, the effect of cathode temperature and laser wavelength on quantum efficiency is known only for limited conditions. Although it is expected to be able to lengthen the required wavelength of photocathode drive laser by heating cathodes, laser with photon energy under the work function has not been tested. Revealing them enables us to design the cost minimum accelerators. In this research, photoemission properties of LaB6 and CeB6 with various excitation photon energies will be investigated under various temperatures of the materials. Those materials have similar work function, but CeB6 have one order of magnitude smaller Richardson constant than LaB6***. By comparing photoemission properties of these materials, impact of Richardson constant on the photoemission properties will be investigated.
* S. Thorin et al. Proc of FEL2009, 310
** D. Satoh et al. Proc of IPAC2014, 679
*** J.M. Lafferty, J. Appl. Phys. 22, (1951), 299
 		 
slides icon Slides SUPSS038 [0.996 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEOAB03  
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SUPSS039
 Fabrication of Two Dimensional Nano-Scale Photocathode Arrays in Transparent Conductor for High Coherence Beam Generation  
WEPMY040   use link to access more material from this paper's primary paper code  
 
  • T. Shibuya
    TIT, Tokyo, Japan
  • N. Hayashizaki
    RLNR, Tokyo, Japan
  • M. Yoshida
    KEK, Ibaraki, Japan
  
  Electron beam quality for particle source of diffractometer is mainly characterized by transverse and longitudinal coherent length, beam current density and so on. In order to improve a transverse coherent length, it is practically essential to minimize electrons emission area size as small as possible. However, the size of photoemission area is limited by focused laser beam size on the surface of cathode, and the scale is several microns. Aim to get definite overlap between the focused laser and emitters for effective irradiation, as well as to realize generation of nano-scale size electron beam, nano-scale photocathode arrays in transparent conductor are essential. Therefore, I propose to fabricate the nano-scale emission area in replace of limiting the focused laser size on the photocathode for achieving high coherence beam. The fabrication process of this novel nano-scale emitter configuration and its fundamental properties are presented in this paper.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMY040  
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SUPSS041
 Study of Achieving Low Energy Beam by Energy Degradation and Direct Resonance Extraction in a Compact Ring  
MOPOY003   use link to access more material from this paper's primary paper code  
 
  • G.R. Li, X.W. Wang, Z. Yang, H.J. Yao, Q. Zhang, S.X. Zheng
    TUB, Beijing, People's Republic of China
  • X. Guan
    Tsinghua University, Beijing, People's Republic of China
  
  We have designed a compact proton synchrotron(7~230 MeV) for applications like proton therapy and space environment study. These applications may require slow extraction from 10~230 MeV. Traditionally, the low energy beam(10~70 MeV) is achieved by energy degradation from high energy beam which may cause beam lose and energy spread increase, because the beam quality may suffer from magnetic remanence, power ripple and strong space charge effects in low energy stage. To achieve high quality beam directly from resonance extraction, we study these effects by performing multi-particle simulation. Methods of improving beam quality are discussed.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY003  
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SUPSS043
 Status of the First CH-Cavities for the New Superconducting CW Heavy Ion LINAC@GSI  
MOPOY019   use link to access more material from this paper's primary paper code  
 
  • M. Basten, M. Amberg, M. Busch, F.D. Dziuba, H. Podlech, M. Schwarz
    IAP, Frankfurt am Main, Germany
  • K. Aulenbacher
    IKP, Mainz, Germany
  • K. Aulenbacher, W.A. Barth, V. Gettmann, S. Mickat, M. Miski-Oglu
    HIM, Mainz, Germany
  • W.A. Barth, M. Heilmann, S. Mickat, S. Yaramyshev
    GSI, Darmstadt, Germany
  
  In the field of Super Heavy Elements (SHE) a superconducting (sc) continuous wave (cw) high intensity heavy ion LINAC is highly desirable. Currently a multi-stage R&D program conducted by GSI, HIM and IAP* is in progress. The baseline linac design composes a high performance ion source, a new low energy beam transport line, a (cw) upgraded High Charge State Injector (HLI), and a matching line (1.4 MeV/u) followed by the new sc-DTL LINAC for acceleration up to 7.3 MeV/u. The commissioning of the first CH cavity (Demonstrator), in a horizontal cryo module with beam is a major milestone in 2016**. The advanced demonstrator comprises constant-beta sc Crossbar-H-mode (CH) cavities operated at 217 MHz. Presently, the first two sc CH cavities of the advanced demonstrator are under construction at Research Instruments (RI), Bergisch Gladbach, Germany. A string of cavities and focusing elements build from several short CH-cavities with 8 gaps, without girders is recommended. The new design potentially reduces the overall technical risks during the fabrication and the pressure sensitivity through stiffening brackets. The present status of the first two sc cavities will be presented.
* W.Barth et al., Further R&D for a new Superconducting cw Heavy Ion LINAC@GSI, IPAC'14
**F.Dziuba et al., Measurements on the Superconducting 217 MHz CH Cavity during the Manufacturing Phase, SRF2015 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY019  
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SUPSS044
 Prototype Design of a Newly Revised CW RFQ for the High Charge State Injector at GSI  
MOPOY020   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, O.K. Kester
    GSI, Darmstadt, Germany
  
  Within the scope of the FAIR project (Facility for Antiproton and Ion Research) at GSI Helmholtz Centre for Heavy Ion Research in Darmstadt, Germany, the front end of the existing High Charge State Injector (HLI) is planned to be upgraded for cw operation. The required newly revised 4-Rod RFQ structure is currently being designed at the Institute for Applied Physics (IAP) of the Goethe University of Frankfurt. It will be operated with a 100 kW power amplifier at 108 MHz. At first instance a dedicated 4-stem prototype, which is based on the RFQ design for MYRRHA* and FRANZ**, is planned to be manufactured in order to validate the simulated RF performance, thermal behavior and mechanical characteristics in continuous operation. The RF simulations as well as basic thermal simulations are done using CST Studio Suite. In order to prevent oscillations of the electrodes mechanical eigenmodes are analyzed using ANSYS Multiphysics. In addition the ANSYS software allows more sophisticated simulations regarding the cooling capability by considering fluid dynamics in water cooling channels, thus providing a more detailed thermal analysis.
*C. Zhang, H. Podlech, New Reference Design of the European ADS RFQ Accelerator For MYRRHA, IPAC2014
**M. Heilmann et al., A Coupled RFQ-IH Cavity for the Neutron Source FRANZ, IPAC2013
 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY020  
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SUPSS045
 Design Study on an Injector RFQ for Heavy Ion Accelerator Facility  
MOPOY033   use link to access more material from this paper's primary paper code  
 
  • W. Ma, Y. He, L. Lu, X.B. Xu, Z.L. Zhang, H.W. Zhao
    IMP/CAS, Lanzhou, People's Republic of China
  
  A Low Energy Accelerator Facility (LEAF) was launched as a pre-research facility for High Intensity heavy ion Accelerator Facility (HIAF). The LEAF consists of a 2-mA U34+ electron cyclotron resonance (ECR) type ion source with 300-kV extraction voltage, a low energy beam transport (LEBT) line with a multi-harmonic buncher (MHB), a CW 81.25MHz radio frequency quad-rupole (RFQ) accelerator which could accelerate heavy ions from 14 keV/u up to 500 keV/u, a triplet magnet for medium energy beam transport and an experimental platform for nuclear physics. After describing the selected structure, an octagonal cavity with π-mode stabilizing loop (PISL) type structure was adopted and simulated. In this paper, the detailed electromagnetic design and ther-mal simulation of the LEAF-RFQ will be reported.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOY033  
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SUPSS046
 Local Optics Corrections in the HL-LHC IR  
THPMR040   use link to access more material from this paper's primary paper code  
 
  • J.M. Coello de Portugal, F.S. Carlier, A. Garcia-Tabares, A. Langner, E.H. Maclean, L. Malina, T. Persson, P.K. Skowroński, R. Tomás
    CERN, Geneva, Switzerland
  
  For the high luminosity upgrade of the LHC optics correction in the interaction regions is expected to be challenged by the very low β* and the sizable expected quadrupolar errors in the triplet. This paper addresses the performance and limitations of the segment-by-segment technique to correct quadrupolar and skew quadrupolar errors in the HL-LHC IR via computer simulations. Required improvements to this technique and possible combinations with other correction approaches are also presented including experimental tests in the current LHC IR.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMR040  
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SUPSS047
 Optics-measurement-based BPM Calibration  
THPMB041   use link to access more material from this paper's primary paper code  
 
  • A. Garcia-Tabares, F.S. Carlier, J.M. Coello de Portugal, A. Langner, E.H. Maclean, L. Malina, T. Persson, P.K. Skowroński, M. Solfaroli Camillocci, R. Tomás
    CERN, Geneva, Switzerland
  
  The LHC beta functions (β) can be measured using the phase or the amplitude of betatron oscillations obtained with beam position monitors (BPMs). Using the amplitude information results in a β measurement affected by BPM calibration. This work aims at calibrating BPMs using optics measurements. For this, βs from amplitude and phase and normalized dispersion obtained from many different measurements in 2015 with different optics and corrections are analyzed. Simulations are also performed to support the analyses.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB041  
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SUPSS048
 Chromaticity Compensation Schemes for the Arc Lattice of the FCC-ee Collider  
THPOR002   use link to access more material from this paper's primary paper code  
 
  • B. Härer
    KIT, Karlsruhe, Germany
  • A. Doblhammer, B.J. Holzer
    CERN, Geneva, Switzerland
  
  FCC-ee is an 100 km e+/e− collider that is being designed within the Future Circular Collider Study organised by CERN. It's layout is optimised for precision studies and rare decay observations in the range of 90 to 350 GeV center of mass energy with luminosities in the order of 1035 cm-2s-1. Extremely small vertical beta functions of 1 - 2 mm are required at the two interaction points to reach this goal. The strong focusing required in the final doublet quadrupoles drives the chromaticity to more than -2000 units, far beyond the values that had been achieved in previous storage rings. As a consequence a pure linear chromaticity compensation scheme will not be sufficient to obtain the required ± 2 % energy acceptance. A state of the art multi-family sextupole scheme will have to be combined with a local chromaticity correction. This paper presents the design of the arc lattice, optimised for highest momentum acceptance and the results of systematic studies of the sextupole scheme in the arcs in order to gain highest chromaticity performance.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOR002  
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SUPSS049
 Optimization of the Dechirper for Electron Bunches of Arbitrary Longitudinal Shapes  
TUOAB01   use link to access more material from this paper's primary paper code  
 
  • J.M. Seok, M. Chung
    UNIST, Ulsan, Republic of Korea
  • J.H. Han, J.H. Hong, H.-S. Kang
    PAL, Pohang, Kyungbuk, Republic of Korea
  
  Dechirper is a passive device composed of a vacuum chamber of two corrugated, metallic plates with an adjustable gap. By introducing a small offset in the dechirper with respect to the reference axis, one might generate transverse wakefields and use the dechirper as a deflector. Understanding the interactions between electron beams of various longitudinal shapes with the wakefields generated by the dechirper is important to assess the feasibility of the dechirper for use as a deflector. Recently, using a set of alpha-BBO crystals, shaping of laser pulses and electron bunches on the order of ps is tested at the Injector Test Facility (ITF) of Pohang Accelerator Laboratory (PAL). Furthermore, we have investigated propagation of electron bunches of arbitrary longitudinal shapes through the dechirper. In the numerical simulations, we observed that the arbitrary electron beams were successful deflected except for lethal beam shape problems. Hence, in this work, we study optimization of the dechirper for electron bunches of arbitrary longitudinal shapes, using analytical theory and numerical simulations with the ASTRA and ELEGANT codes.  
slides icon Slides SUPSS049 [1.631 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUOAB01  
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SUPSS050
 Muon Charge Separation by Mixed Structure of Dipoles and Solenoids  
THPMB015   use link to access more material from this paper's primary paper code  
 
  • Y.P. Song, H.T. Jing, J.Y. Tang
    IHEP, Beijing, People's Republic of China
  
  A charge separation system comprised by dipoles and solenoids is described which aims to separate positive particles and negative particles apart in secondary beam with a large emittance and huge momentum spread, particularly for mixed-charge muon beams. Nonlinear effect and fringe field effect due to large aperture and large moment range are crucial under this circumstance, which make the charge separation extremely complicated. The design schemes by dipoles and bent solenoids and also simulation results are showed in the paper.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB015  
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SUPSS051
 Studies on Electron Beam Injector System for Linac-based Coherent Thz Source in Thailand  
THPMB052   use link to access more material from this paper's primary paper code  
 
  • W. Thongpakdi, S. Rimjaem
    Chiang Mai University, Chiang Mai, Thailand
  
  Funding: The Department of Physics and Materials Science, Faculty of Science, Chiang Mai University and the Development and Promotion of Science and Technology Talents Project (DPST).
At the Plasma and Beam Physics Research Facility, Chiang Mai University, a thermionic cathode RF electron gun and alpha magnet are used together as an injector system for a linac-based THz source. Investigate the optimal performance of the injector system, beam dynamic simulations are performed by computer codes PARMELA, ASTRA and ELEGANT. The input 3D field distributions of the RF-gun for PARMELA and ASTRA simulations are obtained from the RF modeling program CST Microwave Studio. The beam transport calculation using the program ELEGANT is performed to study behavior of electrons from the gun exit through the alpha magnet, a travelling wave linac, magnet elements, drift tubes, and related beam diagnostic components. Energy slits inside the alpha magnet vacuum chamber is used to select electrons with desired kinetic energies. The alpha magnet compresses electron bunches with certain bunch length before the beam entering the linac to obtain minimum energy spread and shortest bunch length at the experimental station. Results of electron beam optimization with appropriated conditions for generation of intense coherent THz radiation will be reported and discussed in this contribution.
This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Materials Science, Faculty of Science, Chiang Mai University and DPST. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMB052  
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SUPSS052
 Longitudinal Wakefields in the Undulator Section of SXFEL User Facility  
MOPOR005   use link to access more material from this paper's primary paper code  
 
  • M. Song, H.X. Deng, C. Feng, D. Huang, B. Liu, D. Wang
    SINAP, Shanghai, People's Republic of China
  
  Shanghai soft x-ray free electron laser (SXFEL) user facility based on multi-stage seeded-FEL and self-amplified spontaneous emission (SASE) is recently proposed, which is aiming at generating 4-2nm fully-coherent, high-brightness FEL pulse. In this paper, the wakefields arise from the resistive wall and surface roughness in the vacuum chamber is obtained by theoretical models*. And the computations of geometric wakefields are carried out using ABCI**. According to the tracked beam profile, the overall wakefields in the undulator section of SXFEL user facility are presented.
* K. Bane, G. Stupakov, SLAC-PUB-15951, May 2014.
** ABCI website: http://abci.kek.jp/abci.htm 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR005  
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SUPSS054
 Trapped Ion Effects and Mitigation During High Current Operation in the Cornell DC Photoinjector  
TUPOR031   use link to access more material from this paper's primary paper code  
 
  • S.J. Full, A.C. Bartnik, I.V. Bazarov, J. Dobbins, B.M. Dunham, G.H. Hoffstaetter
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: U.S. Department of Energy (Grant No. DE-SC0012493), National Science Foundation (Award No. NSF-DMR 0807731)
The Cornell high intensity photoinjector reaches a new regime of linac beam parameters where high continuous-wave electron beam currents lead to ion trapping. Above 10 mA, we have observed beam trips that limit stable machine operation to approximately 10-15 minutes. By applying known ion clearing methods, the machine lifetime increases to at least 24 hours of continuous operation, suggesting that trapped ions are the most likely cause of the trips. In this paper we share some of our observations ion trapping in the photoinjector, as well as experimental tests of three common ion mitigation methods: clearing electrodes, beam shaking and bunch gaps. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR031  
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SUPSS055
 Single Bunch Longitudinal Instability in the CERN SPS  
TUPOR009   use link to access more material from this paper's primary paper code  
 
  • A. Lasheen, T. Bohl, S. Hancock, T. Roggen, E.N. Shaposhnikova
    CERN, Geneva, Switzerland
  • E. Radvilas
    Gediminas Technical University, Vilnius, Lithuania
  
  The longitudinal single bunch instability observed in the SPS leads to uncontrolled emittance blow-up and limits the quality of high intensity beams required for the High Luminosity LHC and AWAKE projects at CERN. The present SPS impedance model developed from a thorough survey of machine elements was used in macro-particle simulations (with the code BLonD) of the bunch behavior through the acceleration cycle. Comparison of simulations with measurements of the synchrotron frequency shift, performed on the SPS flat bottom to probe the impedance, show a reasonable agreement. During extensive experimental studies various beam and machine parameters (bunch intensity, longitudinal emittance, RF voltage, with single and double RF systems) were scanned in order to further benchmark the SPS impedance model with measurements and to better understand the mechanism behind the instability. It was found that the dependence of instability threshold on longitudinal emittance and beam energy has an unexpected non-monotonic behavior, leading to islands of (in)stability. The results of this study are presented and can be used to define possible parameter settings for the future CERN projects.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR009  
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SUPSS056
 Conditions for CSR Microbunching Gain Suppression  
TUOAB02   use link to access more material from this paper's primary paper code  
 
  • C.-Y. Tsai
    Virginia Polytechnic Institute and State University, Blacksburg, Virginia, USA
  • S. Di Mitri
    Elettra-Sincrotrone Trieste S.C.p.A., Basovizza, Italy
  • D. Douglas, R. Li, C. Tennant
    JLab, Newport News, Virginia, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The coherent synchrotron radiation (CSR) of a high brightness electron beam traversing a series of dipoles, such as transport arcs, may result in phase space degradation. On one hand, the CSR can perturb electron transverse motion in dispersive regions along the beamline, causing emittance growth. On the other hand, the CSR effect on the longitudinal beam dynamics could result in microbunching gain enhancement. For transport arcs, several schemes have been proposed* to suppress the CSR-induced emittance growth. Similarly, several scenarios have been introduced** to suppress CSR-induced microbunching gain, which however mostly aim for linac-based machines. In this paper we try to provide sufficient conditions for suppression of CSR-induced microbunching gain along a transport arc, analogous to*. Several example lattices are presented, with the relevant microbunching analyses carried out by our semi-analytical Vlasov solver***. The simulation results show that lattices satisfying the proposed conditions indeed have microbunching gain suppressed. We expect this analysis can shed light on lattice design approach that could suppress the CSR-induced microbunching gain.
*D.Douglas et al, JLAB-ACP-14-1751, S.DiMitri et al, PRL (2013), R.Hajima, NIMA (2004), Y.Jiao et al, PRSTAB (2014)
**Z.Huang et al, PRSTAB (2004), Saldin et al, NIMA (2004)
***C.Tsai et al, FEL'15 		 
slides icon Slides SUPSS056 [6.484 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUOAB02  
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SUPSS057
 Beam Halo Measurements using Vibrating Wire at the KOMAC  
MOPOR037   use link to access more material from this paper's primary paper code  
 
  • D. Choe, M. Chung, S.Y. Kim
    UNIST, Ulsan, Republic of Korea
  • S.G. Arutunian, A.V. Margaryan
    ANSL, Yerevan, Armenia
  • E.G. Lazareva
    YSU, Yerevan, Armenia
  
  In high-intensity particle accelerators, due to the fact that preventing beam loss plays a crucial role in con-ducting any experiments, it is important to measure and control the beam halo. Fortunately, it is feasible nowadays to measure the beam halo region thanks to the development of several sensitive beam scanning methods, including the vibrating wire technique. Since the vibrating wire is exceptionally sensitive to the heat deposition by the beam particles, it can be used to scanning the beam profile. This study will be concentrated on the precise beam profile measurement using the vibrating wire at the Korea Multi-Purpose Accelerator Complex (KOMAC) facility. First, we describe the best condition to construct beam profile measurement experiment. Finally, we present the results of the beam halo measurements performed with 20 MeV proton beam at the KOMAC facility  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPOR037  
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SUPSS058
 Light Optics for Optical Stochastic Cooling  
WEPOY022   use link to access more material from this paper's primary paper code  
 
  • M.B. Andorf, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • V.A. Lebedev, P. Piot, J. Ruan
    Fermilab, Batavia, Illinois, USA
  
  Funding: This work was supported by the US DOE under contract DE-SC0013761 with Northern Illinois University. Fermilab is operated by the Fermi Research Alliance LLC under US DOE contract DE-AC02-07CH11359.
In Optical Stochastic Cooling (OSC) radiation generated by a particle in a "pickup" undulator is amplified and transported to a downstream "kicker" undulator where it interacts with the same particle which radiated it. Fermilab plans to carry out both passive (no optical amplifier) and active (optical amplifier) tests of OSC at the Integrable Optics Test Accelerator (IOTA) currently in construction*. The performace of the optical system is analyzed with simulations in Synchrotron Radiation Workshop (SRW) accounting for the specific temporal and spectral properties of undulator radiation and being augmented to include dispersion of lens material.
* V. Lebedev, et al., Proc. COOL'15 (in press, 2015).
 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY022  
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SUPSS059
 Longitudinal Bram Dynamics at Rf-Compressor  
WEPOY015   use link to access more material from this paper's primary paper code  
 
  • A.V. Andrianov
    BINP SB RAS, Novosibirsk, Russia
  
  Nowadays the usage of charged particle beams for study of nature became widespread. Modern experiments are require particle beams with duration around hundreds femtosecond. Relatively simple and cheap method of production such pulses is using RF-gun with photocathode and then the special insertion device which compress the beam. The paper described the RF-compressor for the electron beam. In result of work was obtained a device configuration. Electromagnetic field configuration and distribution were simulated for the configuration. Beam dynamics was computed in this field distribution. Incoming beam parameters are following: beam length is 1-5ps, beam charge is 0.1-2pC and energy is 3MeV. Output beam duration was compressed to less than 150fs. Influence of RF-compressor at beam parameters was estimated.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY015  
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SUPSS060
 Study on Electron Beam Transverse Emittance at the Linac-based THz Laboratory in Thailand  
WEPOY018   use link to access more material from this paper's primary paper code  
 
  • K. Kosaentor
    IST, Chiang Mai, Thailand
  • S. Rimjaem
    Chiang Mai University, Chiang Mai, Thailand
  
  This research focuses on simulation of transverse emittance of electron beams, which are produced from a thermionic RF-gun at the Plasma and Beam Physics (PBP) Research Facility, Chiang Mai University (CMU). The RF-gun is used to together with an alpha magnet for serving as the electron injector system for the PBP linac-based THz source. The quadrupole scan technique is utilized to measure the transverse beam emittance at the entrance of the alpha magnet. The experimental setup consists of quadrupole magnets with a maximum gradient of 7.01 T/m, a drift tube, and a movable fluorescent screen station. Beam dynamic simulations by using the computer codes PARMELA and ELEGANTare performed to track electrons from the cathode to the experimental station. In this contribution, the emittance values from simulations including the space charge effects will be reported.
This work has been supported by the CMU Junior Research Fellowship Program, Department of Physics and Material Science, Faculty of science, Chiang Mai University. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY018  
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SUPSS061
 First BTF Measurements at the Large Hadron Collider  
WEPOY030   use link to access more material from this paper's primary paper code  
 
  • C. Tambasco, A. Boccardi, X. Buffat, K. Fuchsberger, M. Gąsior, R. Giachino, T. Lefèvre, T.E. Levens, T. Pieloni, M. Pojer, B. Salvachua, M. Solfaroli Camillocci
    CERN, Geneva, Switzerland
  • J. Barranco, C. Tambasco
    EPFL, Lausanne, Switzerland
  
  During the Run I in 2012, several instabilities have been observed at the Large Hadron Collider (LHC) during the Betatron squeeze. The predictions of instability thresholds are based on the computation of the beam Landau damping by calculating the Stability Diagrams (SD). These instabilities could be explained by a deterioration of the SD due to beam-beam resonance excitation which could change the particle distributions. Beam Transfer Functions (BTF) provide a measurement of the Stability Diagram. The BTFs are sensitive to the particle detuning with amplitude as well as to the particle distributions therefore they represent a powerful tool to understand experimentally the stability of beams during the LHC operational cycle. First BTF measurements at the LHC are presented for different machine configurations and settings and compared to predictions.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY030  
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SUPSS062
 High Power RF Generation From a W-Band Corrugated Structure Excited by a Train of Electron Bunches  
WEPOY025   use link to access more material from this paper's primary paper code  
 
  • D. Wang, C.-X. Tang
    TUB, Beijing, People's Republic of China
  • S.P. Antipov, C.-J. Jing, J.Q. Qiu
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • M.E. Conde, D.S. Doran, W. Gai, G. Ha, G. Ha, W. Liu, J.G. Power, E.E. Wisniewski
    ANL, Argonne, Illinois, USA
  • V.A. Dolgashev
    SLAC, Menlo Park, California, USA
  
  We report on the generation of multi-megawatt peak RF power at 91textGHz, using an ultrarelativistic electron bunch train to excite electromagnetic fields in a high-impedance metallic corrugated structure. This device can be used as a power source for high gradient acceleration of electrons. To achieve precise control of the wakefield phase, a long range wakefield interferometry method was developed in which the RF energy due to the interference of the wakefields from two bunches was measured as a function of the bunch separation.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY025  
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SUPSS063
 Fast Tracking of Nonlinear Dynamics in the ESS Linac Simulator via Particle-Count Invariance  
WEPOY041   use link to access more material from this paper's primary paper code  
 
  • B.T. Folsom, E. Laface
    ESS, Lund, Sweden
  
  Real-time beam modeling has been used in accelerator diagnostics for several decades. Along the way, the theory for matrix calculations of linear forces has matured, allowing for fast calculations of a beam's momentum and position distributions. This formalism becomes complicated and ultimately breaks down with high-order beam elements like sextupoles. Such elements can be accurately modeled with a Lie-algebra approach, but these techniques are generally implemented in slower, offline multiparticle tracking software. Here, we demonstrate an adaptation of the conventional Lie techniques for rapid first-order tracking of position, which is accomplished by treating a bunch's particle count as an invariant.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY041  
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SUPSS064
 A Differential Algebraic Framework for the Fast Indirect Boundary Element Method  
WEPOY050   use link to access more material from this paper's primary paper code  
 
  • A.J. Gee, B. Erdelyi
    Northern Illinois University, DeKalb, Illinois, USA
  • B. Erdelyi
    ANL, Argonne, USA
  
  Beam physics at the intensity frontier must account for the beams' realistic surroundings on their dynamics in an accurate and efficient manner. Mathematically, the problem can be expressed as a Poisson PDE with given boundary conditions. Commonly, the Poisson boundary value problem is solved locally within many volume elements. However, it is known the PDE may be re-expressed as indirect bound- ary integral equations (BIE) which give a global solution*. By solving the BIEs on M surface elements, we arrive at the indirect boundary element method (iBEM). Iteratively solving this dense linear system of form Ax = b scales like (miterations M2 ). Accelerating with the fast multipole method (FMM) can reduce this to O(M) if miterations << M. For N evaluation points, the total complexity would be O(M) + O(N) or O(N) with N = M. We have implemented a constant element version of this fast iBEM based on our previous work with the FMM in the differential algebraic (DA) framework**. This implementation is to illustrate the flexibility and accuracy of our method. A future version will focus on allowing for higher order elements.
* Sauter, S. and C. Schwab. Boundary Element Methods (2011)
** Abeyratne, S., S. Manikonda, and B. Erdelyi. "A novel differential algebraic adaptive fast multipole method." IPAC 2013: 1055-1057. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY050  
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SUPSS065
 Space Charge Compensation in Low Energy Beam Lines  
WEPOY033   use link to access more material from this paper's primary paper code  
 
  • F. Gérardin, N. Chauvin, D. Uriot
    CEA/IRFU, Gif-sur-Yvette, France
  • M.A. Baylac, D. Bondoux, F. Bouly
    LPSC, Grenoble Cedex, France
  • A. Chancé, O. Napoly, N. Pichoff
    CEA/DSM/IRFU, France
  
  The dynamics of a high intensity beam with low energy is governed by its space-charge forces which may be responsible of emittance growth and halo formation due to their non-linearity. In a low energy beam transport (LEBT) line of a linear accelerator, the propagation of a charged beam with low energy causes the production of secondary particles created by the interaction between the beam and the background gas present in the accelerator tube. This phenomenon called space-charge compensation is difficult to characterize analitically. In order to obtain some quantitative to characterize the space-charge compensation (or neutralization), numerical simulations using a 3D PIC code have been implemented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOY033  
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SUPSS066
 Bunch Length Measurement at Bunch by Bunch in Harmonics Method at Shanghai SSRF Storage Ring  
MOPMB048   use link to access more material from this paper's primary paper code  
 
  • L.W. Duan, Y.B. Leng, R.X. Yuan
    SINAP, Shanghai, People's Republic of China
  • N. Zhang
    SSRF, Shanghai, People's Republic of China
  
  Harmonics method in frequency domain is an effective and inexpensive bunch length measurement method. With advances in technology, it is possible to do bunch length measurement at bunch by bunch using electronic method. We design and make an electronic system to realize metering at bunch by bunch, and believe it has reasonable bunch length resolution. All selected harmonic signals will be mixed down to 500 MHz and digitized at bunch-by-bunch rate by a multi-channel DBPM processor. The primary beam experiment results will be presented and discussed in this paper.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB048  
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SUPSS067
 First Tests of SuperKEKB Luminosity Monitors during 2016 Single Beam Commissioning  
MOPMB006   use link to access more material from this paper's primary paper code  
 
  • D. El Khechen, P. Bambade, A. Blin, P. Cornebise, D. Jehanno, V. Kubytskyi, Y. Peinaud, C. Rimbault
    LAL, Orsay, France
  • Y. Funakoshi, Y. Ohnishi, S. Uehara
    KEK, Ibaraki, Japan
  
  The SuperKEKB e+e− collider aims to reach a very high luminosity of 8 1035 cm-2s−1, using highly focused ultra-low emittance bunches colliding every 4ns. Fast luminosity monitoring is required for luminosity feedback and optimisation in presence of dynamic imperfections. The aimed relative precision is about 10-3 in 1ms, which can be in principle achieved thanks to the very large cross-section of the radiative Bhabha process at zero degree scattering angle. Diamond, Cherenkov and scintillator sensors are to be placed just outside the beam pipe, downstream of the interaction point in both rings, at locations with event rates consistent with the aimed precision and small enough backgrounds from single-beam particle losses. The initial configuration installed for the 2016 "phase 1" single beam commissioning will be described, including the sensors, mechanical setup, readout electronics and first stage DAQ. Preliminary measurements and analysis of beam gas Bremsstrahlung loss data collected with the luminosity monitors will be reported and compared with a detailed simulation, for several experimental conditions during the SuperKEKB commissioning.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB006  
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SUPSS068
 Using a Single Shot Spectrometer to Determine the Spectral Characteristics of the Beam as a Result of Micro-bunching Instabilities  
MOPMR036   use link to access more material from this paper's primary paper code  
 
  • A. Finn, P. Karataev
    JAI, Egham, Surrey, United Kingdom
  • P. Karataev
    Royal Holloway, University of London, Surrey, United Kingdom
  • G. Rehm
    DLS, Oxfordshire, United Kingdom
  
  A single shot spectrometer has been designed and is in operation at the Diamond Light Source (DLS). It is an array of eight Schottky barrier diodes (SBDs) each with a distinct frequency band covering 33-1000 GHz. The aim of the spectrometer is to observe the bursts of coherent synchrotron radiation (CSR) as a result of micro-bunching instabilities (MBI) and stable low alpha modes, where alpha is the momentum compaction factor. In this case, the bursts of CSR occur with wavelengths in the mm regime. SBDs are often implemented as detectors in the millimetre wavelength range and benefit from low noise, excellent sensitivity and ultra-fast responses. The eight SBDs have been individually characterised thus making the results obtained comparable to simulations. Here we present, an analysis of the data obtained via the spectrometer in particular, the bursting nature and spectral characteristics of a sample of beam modes at DLS. Furthermore, the results obtained can be used to confirm simulations.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR036  
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SUPSS069
 First Steps Towards a Single-Shot Longitudinal Profile Monitor: Study of the Properties of Coherent Smith-Purcell Radiation Using the Surface Current Model  
MOPMR040   use link to access more material from this paper's primary paper code  
 
  • H. Harrison, G. Doucas, I.V. Konoplev, A.J. Lancaster
    JAI, Oxford, United Kingdom
  • A. Aryshev, K. Lekomtsev, M. Shevelev, N. Terunuma, J. Urakawa
    KEK, Ibaraki, Japan
  
  Funding: UK STFC, Leverhulme Trust, Photon and Quantum Basic Research Coordinated Development Program (Ministry of Education, Culture, Sports, Science and Technology, Japan)and JSPS KAKENHI.
We propose to use the polarization of coherent Smith-Purcell radiation (cSPr) to separate the signal from background radiation in a single-shot longitudinal bunch profile monitor. We compare simulation and experimental results for the degree of polarization of cSPr generated by a grating with a 1mm periodic structure at the LUCX facility, KEK (Japan). Both experiment and simulation show that the majority of the cSPr signal is polarized in the direction parallel to the grating grooves. The degree of polarization predicted by simulation is higher than the measured result, therefore further investigation is needed to resolve this discrepancy. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR040  
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SUPSS070
 A Versatile Beam Loss Monitoring System for CLIC  
MOPMR024   use link to access more material from this paper's primary paper code  
 
  • M. Kastriotou, S. Döbert, W. Farabolini, E.B. Holzer, E. Nebot Del Busto, F. Tecker
    CERN, Geneva, Switzerland
  • M. Kastriotou, E. Nebot Del Busto, C.P. Welsch
    The University of Liverpool, Liverpool, United Kingdom
  • M. Kastriotou, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  
  The design of a potential CLIC beam loss monitoring (BLM) system presents multiple challenges. To successfully cover the 48 km of beamline, ionisation chambers and optical fibre BLMs are under investigation. The former fulfils all CLIC requirements but would need more than 40000 monitors to protect the whole facility. For the latter, the capability of reconstructing the original loss position with a multi-bunch beam pulse and multiple loss locations still needs to be quantified. Two main sources of background for beam loss measurements are identified for CLIC. The two-beam accelerator scheme introduces so-called crosstalk, i.e. detection of losses originating in one beam line by the monitors protecting the other. Moreover, electrons emitted from the inner surface of RF cavities and boosted by the high RF gradients may produce signals in neighbouring BLMs, limiting their ability to detect real beam losses. This contribution presents the results of dedicated experiments performed in the CLIC Test Facility to quantify the position resolution of optical fibre BLMs in a multi-bunch, multi-loss scenario as well as the sensitivity limitations due to crosstalk and electron field emission.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR024  
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SUPSS071
 Electron Bunch Length Measurement Using Coherent Radiation Source of fs-THz accelerator at Pohang Accelerator Laboratory  
MOPMR003   use link to access more material from this paper's primary paper code  
 
  • J.H. Ko, I.S. Ko
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • S.H. Jung, H.-S. Kang, I.S. Ko, J. Park
    PAL, Pohang, Kyungbuk, Republic of Korea
  
  A Michelson interferometer was installed at the femtosecond (fs) terahertz (THz) Accelerator of Pohang Accelerator Laboratory(PAL) to measure a subpicosecond order electron bunch length. To measure an ultra-short electron bunch length, we use reconstruction process and fast fourier transform. Currently, we are generating THz radiation with the pulse energy of 7μJ by means of coherent transition radiation (CTR) from a 65-MeV electron beam of the fs-THz accelerator. In this paper, we show the how to make a longitudinal distribution of electron bunch and the radiation intensity difference between CTR and Coherent edge radiation (CER) for nondestructive electron bunch length measurement. And we report the measurement methods to get the fine electron bunch length information.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR003  
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SUPSS072
 Design and Simulation of Button Beam Position Monitor for IR-FEL*  
MOPMB042   use link to access more material from this paper's primary paper code  
 
  • X.Y. Liu, P. Lu, B.G. Sun, L.L. Tang, 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 Science Foundation of China (11575181, 11175173)
A new button-type beam position monitor(BPM) was designed for the IR-FEL project. Firstly, the longitudinal size of BPM needs to be short enough to save space because the entire machine of IR-FEL is very compact. And in the matter of installation problem, all four electrodes are deviated 30 degrees from the horizontal axis. Then, according to these two limited conditions and beam parameters, we builded up a simple model and did some simulated calculations to ensure a good performance of position resolution, which should be better than 50μm. The simulations include an estimation of induced signals in both time and frequency domains, horizontal and vertical sensitivities, mapping figures and so on. This button BPM will be manufactured in the near future and then we can do some off-line experiments to test it.
# Corresponding author (email: bgsun@ustc.edu.cn) 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB042  
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SUPSS073
 Employing Beam-Gas Interaction Vertices for Transverse Profile Measurements  
MOPMR027   use link to access more material from this paper's primary paper code  
 
  • M.N. Rihl, A. Alexopoulos, V. Baglin, C. Barschel, E. Bravin, G. Bregliozzi, N. Chritin, B. Dehning, M. Ferro-Luzzi, C. Gaspar, M. Giovannozzi, R. Jacobsson, L.K. Jensen, O.R. Jones, N.J. Jurado, V. Kain, M. Kuhn, B. Luthi, P. Magagnin, R. Matev, N. Neufeld, J. Panman, V. Salustino Guimaraes, B. Salvant, R. Veness, S. Vlachos
    CERN, Geneva, Switzerland
  • A. Bay, F. Blanc, S. Gianì, G.J. Haefeli, P. Hopchev, T. Nakada, B. Rakotomiaramanana, O. Schneider, M. Tobin, Q.D. Veyrat, Z. Xu
    EPFL, Lausanne, Switzerland
  • R. Greim, W. Karpinski, T. Kirn, S. Schael, G. Schwering, M. Wlochal, A. von Dratzig
    RWTH, Aachen, Germany
  
  Interactions of high-energy beam particles with residual gas offer a unique opportunity to measure the beam profile in a non-intrusive fashion. Such a method was successfully pioneered* at the LHCb experiment using a silicon microstrip vertex detector. During the recent Large Hadron Collider shutdown at CERN, a demonstrator Beam-Gas Vertexing system based on eight scintillating-fibre modules was designed**, constructed and installed on Ring 2 to be operated as a pure beam diagnostics device. The detector signals are read out and collected with LHCb-type front-end electronics and a DAQ system consisting of a CPU farm. Tracks and vertices will be reconstructed to obtain a beam profile in real time. Here, first commissioning results are reported. The advantages and potential for future applications of this technique are discussed.
* LHCb collaboration, Journal of Instrumentation, 9, P12005
** P. Hopchev in Proc. of IPAC 2014, June 15-20, 2014, Dresden Germany 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR027  
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SUPSS074
 Modeling and Experimental Studies of Beam Halo at ATF2  
MOPMB008   use link to access more material from this paper's primary paper code  
 
  • R.J. Yang, P. Bambadepresenter, V. Kubytskyi
    LAL, Orsay, France
  • A. Faus-Golfe, N. Fuster-Martínez
    IFIC, Valencia, Spain
  • T. Naito
    KEK, Ibaraki, Japan
  
  The Accelerator Test Facility 2 (ATF2) at KEK is a prototype of the final focus system for the next generation of Future Linear Colliders(FCL). It aims to focus the beams to tens of nanometer transverse sizes and to provide stability at the few nm level. Achieving these goals requires modelling, measuring and suppressing of the transverse beam halo before the interaction point (IP). This paper presents a beam tail/halo generator based on realistic model and the investigation of vertical and horizontal beam tail/halo distribution at ATF2.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMB008  
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SUPSS075
 Studies of Buffer Gas Cooling of Ion Beams in an RFQ Cooler and Their Transport to the EBIS Charge Breeder  
MOPMR012   use link to access more material from this paper's primary paper code  
 
  • K.H. Yoo, M. Chung
    UNIST, Ulsan, Republic of Korea
  • H.J. Son
    IBS, Daejeon, Republic of Korea
  
  In rare isotope accelerator facilities, an RFQ cooler is often used to manipulate ions. The RFQ cooler is a de-vice to effectively cool and confine ions in gaseous envi-ronment. The RFQ cooler provides a radial electric force to the beam by applying RF voltages to the quadrupole electrode structures, and axial force by applying different DC voltages to the segmented electrodes. The ions are trapped inside the potential well of the RFQ cooler formed by the DC fields, so that they have more colli-sions with the buffer gas. Several important parameters such as transverse emittance can be improved when ion beams are extracted from the RFQ cooler. In order to design an efficient RFQ cooler, which can properly match the ion beams into the EBIS charge breeder, it is essential to analyze evolutions of the transverse emittance and transmission efficiency through the RFQ cooler. Moreo-ver, to minimize emittance growth and maximize trans-mission efficiency, the beam transport line to the EBIS charge breeder needs to be optimized. In this work, we study the methods to apply the mechanism of buffer gas cooling in RFQ cooler to G4beamline and the beam transport line to EBIS charge breeder to TRACK.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMR012  
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SUPSS076
 Signal Archiving System for RISP Heavy-ion Accelerator Control System  
THPOY013   use link to access more material from this paper's primary paper code  
 
  • S.H. Nam
    Korea University, Seoul, Republic of Korea
  • H. Jang, S. Lee, M.J. Park, C.W. Son, H.J. Son
    IBS, Daejeon, Republic of Korea
  • E.-S. Kim
    Korea University Sejong Campus, Sejong, Republic of Korea
  
  RISP control system uses the EPICS real time distributed control system, which is software framework for stable operation of the accelerator. The output signal from all machines and devices must be archived by EPICS framework, and optimized signal archiver system is needed for each accelerator facility. Signal archiver method using the EPICS framework has three significant ways. First is the classic channel archiver using the file base method and the second is the RDB archiver using the relational database. But classic channel archiver has a problem that the index file containing information of data block corresponding PV data mismatch with real data. Also, there is a problem in the performance of file I/O in RDB archiver. SLAC has developed archiver appliance utility to resolve these problems, and the usage of archiver appliance in EPICS community has gradually increased. RISP choose the archiver appliance to also signal archiver solution. However, archiver appliance is not optimized for our RISP heavy-ion accelerator control system. Thus, we will develop the customized signal archiver system for RISP heavy-ion accelerator control system.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY013  
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SUPSS077
 Identification of Intra-bunch Transverse Dynamics for Model-Based Control Purposes at CERN Super Proton Synchrotron  
THOAA01   use link to access more material from this paper's primary paper code  
 
  • O. Turgut, J.E. Dusatko, J.D. Fox, C.H. Rivetta
    SLAC, Menlo Park, California, USA
  • S.M. Rock
    Stanford University, Stanford, California, USA
  
  Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515 and the US LHC Accelerator Research program (LARP). Research supported by FP7 HiLumi LHC http://hilumilhc.web.cern.ch
The high luminosity upgrade plan for the LHC (HiLumi-LHC) increases the bunch intensity and the ultimate intensities require mitigation of possible intra-bunch instabilities in the SPS. Feedback systems can stabilize intra-bunch dynamics. Model based control has promise to stabilize intra-bunch dynamics but it requires a reduced order model which captures the most significant intra-bunch dynamics. We present methods for the estimation of a multi-input multi-output (MIMO) reduced order model of intra-bunch dynamics based on data generated by nonlinear macro particle simulations (CMAD, HeadTail). These linear models are used to design optimal model-based controllers. We evaluate the effectiveness of the MIMO model-based controllers for future high intensity beam conditions within the nonlinear macro particle simulations. We highlight the use of these techniques to stabilize intra-bunch motion and as an important beam dynamics measurement technique. 		 
slides icon Slides SUPSS077 [10.146 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THOAA01  
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SUPSS078
 Pre-alignment of Accelerating Structures for Compact Acceleration and High Gradient using In-situ Radiofrequency Methods  
WEPOR016   use link to access more material from this paper's primary paper code  
 
  • N. Galindo Munoz, N. Catalán Lasheras, A. Grudiev
    CERN, Geneva, Switzerland
  • V.E. Boria
    DCOM-iTEAM-UPV, Valencia, Spain
  • A. Faus-Golfe
    IFIC, Valencia, Spain
  
  Funding: PACMAN is founded under the European Union's 7th Framework Program Marie Curie Actions, grant PITN-GA-2013-606839
To achieve a high accelerating gradient of 100 MV/m, the CLIC project under study at CERN uses a 23 cm long tapered normal-conducting travelling wave Accelerating Structure (AS) operating at 12 GHz. Minimisation of the long-range wakefields (WF) is assured by damping of the HOM through four radial waveguides in each cell without distorting the accelerating mode. As an extension of them, there are four bent waveguides called WF monitors (WFM) in the middle cell with two RF pick-ups. To obtain a small beam emittance in the collision point, micro-metric pre-alignment of the AS is required. We work to find the electrical centre of the AS through the use of the asymmetry in the RF scattering parameters created by an off-centre conductive wire, stretched along the axis. The accuracy required is of 7 μm with a resolution of 3.5 μm for the WFM signals including the acquisition electronics. Our simulations have shown that a resolution of 1 μm is possible using a calibrated VNA. Measurement results and improvements of the final accuracy will be presented and discussed. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR016  
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SUPSS080
 Development of an Analysis Framework for the Beam Instrumentation Interface to the Beam Interlock System at ESS  
THPOY039   use link to access more material from this paper's primary paper code  
 
  • R. Andersson, E. Bargalló, A. Nordt
    ESS, Lund, Sweden
  
  The European Spallation Source (ESS) is currently being built in Lund, Sweden. When it is fully operational in 2025, it will host the most powerful neutron spallation facility in the world. The high-power proton beam needs to be carefully controlled and monitored in order to avoid possible damage to the sensitive equipment. Some of the most critical inputs to the beam interlock system are the beam monitors, delivered by the beam instrumentation group at ESS. In case local protection systems along the accelerator do not foresee a loss of beam, the beam monitors are the last line of defence to stop the proton beam and avoid equipment damage and consecutive downtime. It is essential for the protection of the machine that the whole beam permit signal chain, from monitors to actuators, fulfills strict reliability requirements. This paper describes the role and importance of the beam monitors to correctly measure beam losses and interface with the beam interlock system. It also describes one of several reliability studies that are performed to develop appropriate interfaces in the beam permit signal chain.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY039  
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SUPSS081
 Study of Digital Quench Detection System Based on System-on-Chip Technology  
THPMW008   use link to access more material from this paper's primary paper code  
 
  • J.X. Zhang, X.J. Bian, F.S. Chen, J. Cheng, F. Long
    IHEP, Beijing, People's Republic of China
  
  Quench detection system is a key component of the quench protection system for superconducting magnets. According to operating experience of the quench protec-tion system for BEPCII interaction region superconduct-ing magnets and study in depth on the development process of System-on-Chip, we are establishing a set of digital quench detection system with high integration density and favourable portability by integrating IP cores, custom modules and developing embedded soft-ware on one piece of FPGA chip (Cyclone V SX SoC). The main components of this system are: 1.Hard proces-sor system based-on ARM Cortex-A9 architecture inte-grated with embedded operating system (Linux).2.Floating point DSP based-on soft IP core.3.Function Module Portion designed for different functions such as communicating with front end ADC, timing control, etc. This paper introduces the research progress of the system.
*D.F.Orris, S.Feher, M.J.Lamm, J.Nogiec, S.Sharonov, M.Tartaglia, J.Tompkins, et al.," A digital quench detection system for superconducting magnets", Proceedings of PAC'99, New York, 1999. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW008  
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SUPSS082
 Implementation of SINAP Timing System in Shanghai Proton Therapy Project  
THPOY056   use link to access more material from this paper's primary paper code  
 
  • B.Q. Zhao, M. Liu, C.X. Yin, L.Y. Zhao
    SINAP, Shanghai, People's Republic of China
  
  Funding: The project of SINAP Timing System was supported by the National Natural Science Foundation of China (No. 11305246).
SINAP v2 timing system was implemented in the timing system of Shanghai Proton Therapy Project. The timing system in Shanghai Proton Therapy Project is required not only to generate operation sequence for medical proton synchrotron, but also to realize irradiation flow for beam delivery system. For these purposes, the firmware of SINAP v2 timing system is redesigned to satisfy both event code sequenced broadcasting to generate operation sequence and bidirectional event code transmit to realize irradiation flow. Thanks of the hardware advantage of SINAP v2 timing system, the event receiver (EVR) could transmit event code to event generator (EVG) and then broadcast to timing network by bidirectional transmit ability. By this design, the EVR installed in treatment room has ability to send event code to timing network to stop/start beam during slow extraction. The architecture of the timing system in Shanghai Proton Therapy Project is presented in the paper. The risk analysis is also described in detail. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY056  
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SUPSS083
 Time Response of a Gridded X-ray Beam Ionization Chamber  
THPOY050   use link to access more material from this paper's primary paper code  
 
  • Y.H. Xu, Z.H. Sun
    DongHua University, Songjiang, People's Republic of China
  • D.V. Campen, W.J. Corbett
    SLAC, Menlo Park, California, USA
  • C.L. Li
    East China University of Science and Technology, Shanghai, People's Republic of China
  • W.J. Zhang
    University of Saskatchewan, Saskatoon, Canada
  
  Recently, Quick-Scanning Extended X-ray Absorption Spectroscopy (QEXAS) has become an important tool for in-situ characterization of materials and measurement of associated electronic structure. In this case the time response of the ionization chamber affects the measurement resolution and therefore overall performance of the QEXAS system. Common parallel-plate ionization chambers have a step-response rise time of about 0.1 sec, which does not meet the requirements of QEXAS. To speed up the response, we constructed a gridded ionization chamber with variable bias voltage and optional background gas (N2 or He, respectively). To characterize the system we used a high-frequency beam chopper upstream of the ionization chamber and a high-speed, low-noise preamplifier to measure the step response of the chamber as a function of bias voltage and background gas conditions.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPOY050  
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SUPSS084
 Design and Evaluation of a Broad Band microTCA.4 Based Downconverter  
WEPOR034   use link to access more material from this paper's primary paper code  
 
  • N. Gan, Y.L. Chi, R.L. Liu, X. Ma
    IHEP, Beijing, People's Republic of China
  
  Modern low-level RF (LLRF) control systems of particle accelerators are designed to achieve extremely precise field amplitude and phase regulation inside the accelerating cavities, the RF field signal is usually converted to an intermediate frequency (IF) before being sampled by ADC. As the down-conversion is an important procedure of the digital signal processing in LLRF system, designing a high performance and broad band downconverter compatible with various accelerators will be significant. In this paper, the design of a MicroTCA based downconverter is presented, the major design objective of this module is wider operating frequency range and more flexibility in application. Several performance evaluations on different frequency points of this module have been conducted and the module presents a good performance in the operating frequency range.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR034  
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SUPSS085
 Beam Loading Effects in SSRF Storage Ring  
WEPOR037   use link to access more material from this paper's primary paper code  
 
  • Y. Xia, Q. Chang, Z. Li, K. Xu, Zh.G. Zhang, S.J. Zhao, Y.B. Zhao, X. Zheng
    SINAP, Shanghai, People's Republic of China
  
  The beam current in the storage ring of Shanghai Synchrotron Radiation Facility (SSRF) is now normally 240 mA and projected to be raised to 300 mA. Heavy beam loading will be serious and associated Robinson instability needs to be compressed. In this paper, the beam loading effects in SSRF storage ring and methods to increase current limit will be discussed. .  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPOR037  
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SUPSS086
 Design of Linac with the New Gaskets Clamping Fabrication Technique  
MOPMW005   use link to access more material from this paper's primary paper code  
 
  • F. Cardelli
    INFN-Roma1, Rome, Italy
  • D. Alesini
    INFN/LNF, Frascati (Roma), Italy
  • M. Magi, L. Palumbo
    University of Rome La Sapienza, Rome, Italy
  • F. Pellegrino, V. Pettinacci
    INFN-Roma, Roma, Italy
  
  Recently, a new technique for the realization of high gradient accelerating structures based on the use of gaskets without brazing processes, has been successfully tested at high power on a 1.6 cells RF gun (D. Alesini, et al, PRST 18, 02001, 2015). The new technique developed at the Laboratories of Frascati of the INFN (Italy) in the framework of the SPARC_LAB project has been also adopted for the ELI-NP RF gun. The use of the special gaskets that simultaneously guarantee the vacuum seal and a perfect RF contact allow to avoid the brazing process, strongly reducing the cost, the realization time and the risk of failure. Moreover, without copper annealing due to the brazing process, it is possible, in principle, to decrease the breakdown rate increasing, at the same time, the maximum achievable gradient. The extension of this new fabrication process to complex LINAC structures is the next step on the application of this new technique on particle accelerator. In the paper, we discuss how to extend this process to S-band and C-band Travelling Wave accelerating structures illustrating their electromagnetic design and their mechanical realization.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW005  
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SUPSS087
 Wakefields Studies of High Gradient X-band Accelerating Structure at SINAP  
MOPMW015   use link to access more material from this paper's primary paper code  
 
  • X.X. Huang, W. Fang, Q. Gu, M. Zhang, Z.T. Zhao
    SINAP, Shanghai, People's Republic of China
  
  Shanghai compact hard x-ray free electron laser (CHXFEL)* is now proposed accompanied with a high-gradient accelerating structure, which is the trend of large scale and compact facility. This structure operated at X-band (11424 MHz) holds the promise to achieve high gradient up to 80 MV/m. However, due to its particular property, a more serious wakefields** will be generated, leading to worse beam instability effects. In this paper, the computation of this case will be carried out with simulation. Moreover, analysis and optimization will be adopted to suppress beam instability.
* C. Feng, Z. T. Zhao, Chinese Sci Bull, 2010, 55, 221-227.
** K. Bane, SLAC, NLC-Note 9, Feb. 1995.
 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW015  
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SUPSS090
 Optimization of the RF Cavity of a Low-energy Storage Ring for Thomson Scattering X-Ray Source  
MOPMW023   use link to access more material from this paper's primary paper code  
 
  • L. Ovchinnikova, V.I. Shvedunov
    SINP MSU, Moscow, Russia
  • A. Ryabov
    IHEP, Moscow Region, Russia
  • V.I. Shvedunov
    LEA MSU, Moscow, Russia
  
  Results of optimization of the RF cavity of a low-energy storage ring for Thomson scattering X-ray source are presented. The geometry of 714 MHz RF cavity was optimized to provide maximum shunt impedance taking into account position of higher order modes (HOMs). The number and position of cooling channels were adjusted to minimize frequency shift due to cavity thermal deformations. The waveguide coupler and frequency tuner were calculated. Special attention was paid to detailed calculations of the HOMs parameter and to study of methods to minimize their influence on the storage ring beam dynamics.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW023  
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SUPSS091
 Ultimate Gradient Limitation in Niobium Superconducting Accelerating Cavities  
WEPMR002   use link to access more material from this paper's primary paper code  
 
  • M. Checchin, A. Grassellino, M. Martinello, S. Posen, A. Romanenko
    Fermilab, Batavia, Illinois, USA
  • M. Checchin, M. Martinello
    Illinois Institute of Technology, Chicago, Illlinois, USA
  • J. Zasadzinski
    IIT, Chicago, Illinois, USA
  
  Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The present study is addressed to the theoretical description of the ultimate gradient limitation in SRF cavities. Our intent is to exploit experimental data to confirm models which provide feed-backs on how to improve the current state-of-art. New theoretical insight on the cavities limiting factor can be suitable to improve the quench field of N-doped cavities, and therefore to take advantage of high Q0 at high gradients. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR002  
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SUPSS092
 RF Measurements on High Performance Nb3Sn Cavities  
WEPMR024   use link to access more material from this paper's primary paper code  
 
  • D.L. Hall, M. Liepe, J.T. Maniscalco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  A single-cell 1.3 GHz ILC-shape thin-film Nb3Sn-on-Nb cavity recently achieved accelerating gradients of >16 MV/m with a record Q0 of approx. 2·1010 at 4.2 K, exceeding the power efficiency seen in the current most efficient niobium cavities. A concurrent study of the coating process has resulted in a coating procedure that is capable of replicating this performance in other single-cell cavities. In this paper we demonstrate the RF performance and behaviour of these next generation SRF cavities, with an emphasis on both the impact from both external magnetic fields and the cavity cool down procedure on cavity performance.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR024  
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SUPSS093
 Impurity Doping of Superconducting Radio Frequency Cavities  
THOBB02   use link to access more material from this paper's primary paper code  
 
  • P.N. Koufalis, F. Furuta, G.M. Ge, D. Gonnella, J.J. Kaufman, M. Liepe, J.T. Maniscalco
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: NSF PHYS-1416318
Impurity doping of bulk-niobium superconducting radio frequency (SRF) cavities is a relatively new field of study and the underlying physics is not yet fully understood. Previous studies have shown an increase in the intrinsic quality factor and the corresponding decrease of the temperature-dependent component of the surface resistance of nitrogen-doped cavities with increasing accelerating field.* Here we investigate the effects of alternative inert dopants on the surface resistance and thus the intrinsic quality factor of SRF cavities in pursuit of the optimal dopant and doping level.
A. Grassellino et al., Nitrogen and Argon Doping of Niobium for Superconducting Radio Frequency Cavities. Supercond. Sci. Technol., 26(102001), 2013 		 
slides icon Slides SUPSS093 [4.048 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THOBB02  
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SUPSS094
 Tailoring Surface Impurity Content to Maximize Q-factors of Superconducting Resonators  
WEPMR003   use link to access more material from this paper's primary paper code  
 
  • M. Martinello, M. Checchin, A. Grassellino, O.S. Melnychuk, S. Posen, A. Romanenko, D.A. Sergatskov
    Fermilab, Batavia, Illinois, USA
  • M. Checchin, M. Martinello
    Illinois Institute of Technology, Chicago, Illlinois, USA
  • J. Zasadzinski
    IIT, Chicago, Illinois, USA
  
  Funding: Fermilab is operated by Fermi Research Alliance, LLC under contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Quality factor of superconducting radio-frequency (SRF) cavities is degraded whenever magnetic flux is trapped in the cavity walls during the cooldown. In this contribution we study how the trapped flux sensitivity, defined as the trapped flux surface resistance normalized for the amount of flux trapped, depends on the mean free path. A variety of 1.3 GHz cavities with different surface treatments (EP, 120 C bake and different N-doping) were studied in order to cover the largest range of mean free path nowadays achievable, from few to thousands of nanometers. A bell shaped trend appears for the range of mean free path studied. Over doped cavities falls at the maximum of this curve defining the largest values of sensitivity. In addition, we have also studied the trend of the BCS surface resistance contribution as a function of mean free path, revealing that N-doped cavities follow close to the theoretical minimum of the BCS surface resistance as a function of the mean free path. Adding these results together we unveil that optimal N-doping treatment allows to maximize Q-factor at 2 K and 16 MV/m until the magnetic field fully trapped during the cavity cooldown stays below 10 mG. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR003  
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SUPSS095
 Analyses of 476 MHz and 952 MHz Crab Cavities for JLAB Electron Ion Collider  
WEPMR034   use link to access more material from this paper's primary paper code  
 
  • H. Park, A. Castilla, S.U. De Silva, J.R. Delayen
    ODU, Norfolk, Virginia, USA
  • V.S. Morozov
    JLab, Newport News, Virginia, USA
  
  Center for Accelerator Science at ODU has designed, fabricated and successfully tested a crab cavity for MEIC at Jefferson Lab*. This proof of principle cavity was based on the earlier MEIC design which used 748.5 MHz RF system. The updated MEIC design** utilizes the components from PEP-II. It results in the change on the bunch repetition rate of stored beam to 476.3 MHz. The ion ring collider will eventually require 952.6 MHz crab cavity. This paper will present the analyses of crab cavities of both 476 MHz and 952 MHz options. It compares advantages and disadvantages of the options which provides the MEIC design team important technical information for a system down selection.
* Cryogenic Test of a 750 MHz Superconducting RF Dipole Crabbing Cavity, A. castilla et al, IPAC2014
** MEIC Design Summary, S. Abeyratne et al, arXiv:1504.07961 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR034  
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SUPSS096
 Quadrature Directional Coupling Method for Precise RF Power Measurement  
MOPMY016   use link to access more material from this paper's primary paper code  
 
  • B. Du, G. Huang, L. Lin, Y.T. Liu, Z. Zhao
    USTC/NSRL, Hefei, Anhui, People's Republic of China
  
  The directional coupler is used in the RF transmission and distribution system of accelerator, to measure the forward and backward power. Due to the finite directional isolation of the coupler (20-30dB normally), the crosstalk exists between the bi-directional coupling output signals. For the typical isolation of 26dB, if the bi-directional crosstalk signals are in- or anti- phase, the error of input or reflected power measurement is 10% in case of total reflection, whilst the error of reflected power measurement is 100% in case of VSWR 1.1. A method of quadrature directional coupling measurement is developed to solve the isolation problem. A pair of directional couplers with 90° phase difference are employed to measure the RF power. The influence of the directional crosstalk would be reduced significantly by processing the measurement data. The prototype of quadrature directional couplers is constructed to verify this method. The results showed that the measurement accuracy of quadrature coupler pair after data process is better than 2% for forward measurement, even if the error of single coupler is over 6%. The paper also analyses the error caused by non-ideal quadrature.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY016  
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SUPSS097
 Design Study of Electron Gun for CEPC 650 MHz Klystron  
MOPMY015   use link to access more material from this paper's primary paper code  
 
  • .. Zaib-un-Nisa, D.D. Dong, Z.J. Lu, G. Pei, S.C. Wang, O. Xiao, Z.S. Zhou
    IHEP, People's Republic of China
  • S. Fukuda
    KEK, Ibaraki, Japan
  
  This paper presents the design and simulation of an electron gun for 800 kW CW klystron of which frequency is 650 MHz for CEPC project. An electron gun with a modulating anode is designed using DGUN software. The uniform beam trajectories, with a beam perveance of 0.64μA/V 3/2 are simulated. We employed a Ba-dispenser cathode of radius 35 mm with Φ10 hole at the center and obtained a current density on cathode less than 0.45 A/cm2. The beam trajectories were also simulated over whole tube length with a magnetic field of 207 Gauss. Expecting functions using the modulating anode gun are also described. Proposed beam tester and whole CEPC klystron layout are also shown in this paper.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY015  
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SUPSS098
 Theoretical Analysis and Simulation of a Compact Frequency Multiplier for High Power Millimeter and Terahertz Sources  
MOPMY035   use link to access more material from this paper's primary paper code  
 
  • A.R. Vrielink, S.G. Tantawi, F. Toufexis
    SLAC, Menlo Park, California, USA
  
  As the demands on accelerating gradients and the temporal resolution of beam diagnostics and manipulation schemes grow, millimeter-wave and terahertz (THz) accelerator structures may present a natural solution. The recent advent of a radiofrequency undulator and the development of a 0.45 THz accelerator demonstrate growing interest in this frequency regime; however, growth in this area is limited by the lack of efficient, compact high power sources. We present a novel vacuum electronic device featuring an interaction between a radially bunched electron beam and azimuthally traveling waves. The use of an inward traveling radial sheet beam mitigates space charge effects at the low operating energy of 10-30 keV and allows for a high input beam current of approximately 0.5-10 A. Based on preliminary calculations, these devices could operate from 50 GHz to 250 GHz with tens of kiloWatts of output power, while the expected efficiency would scale from 60% at 80 GHz to 15% at 230 GHz. Here we present the underlying theory, possible structure design, and preliminary results from analytical calculations and simulation.
Tantawi, S. et al. Phys. Rev. Lett. 112, 164802 (April, 2014)
Nanni, E. et al. Nat. Commun. 6, 8486 (October, 2015) 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMY035  
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SUPSS099
 Design of Octupole Channel for Integrable Optics Test Accelerator  
TUPOR030   use link to access more material from this paper's primary paper code  
 
  • S. A. Antipov
    University of Chicago, Chicago, Illinois, USA
  • K. Carlson, A. Valishev, S.J. Wesseln
    Fermilab, Batavia, Illinois, USA
  • R. Castellotti
    SSSUP, Pisa, Italy
  
  We present the design of octupole channel for Integrable Optics Test Accelerator (IOTA). IOTA is a test accelerator at Fermilab, aimed to conduct research towards high-intensity machines. One of the goals of the project is to demonstrate high nonlinear betatron tune shifts while retaining large dynamic aperture in a realistic accelerator design. At the first stage the tune shift will be attained with a special channel of octupoles, which creates a variable octupole potential over a 1.8 m length. The channel consists of 18 identical air-cooled octupole magnets. The magnets feature a simple low-cost design, while meeting the requirements on maximum gradient - up to 1.4 kG/cm3, and field quality - strength of harmonics below 1%. Numerical simulations show that the channel is capable of producing a nonlinear tune shift of 0.08 without restriction of dynamic aperture of the ring.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOR030  
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SUPSS101
 Optimization of the Field Integrals of Two Small Gap IDs for CLS  
TUPMB012   use link to access more material from this paper's primary paper code  
 
  • M.F. Qian, Y.Z. He, H.F. Wang, W. Zhang, Q.G. Zhou
    SINAP, Shanghai, People's Republic of China
  
  An in-vacuum undulator and an in-vacuum wiggler have been developed for CLS at SSRF recently. The period lengths of the undulator and the wiggler are 20mm and 80mm respectively. Both IDs have the minimum gap of 5.2mm. The field integrals were measured for each magnet block with two poles and were sorted in-situ as they were installed on to the girders. Finally the field integrals of the undulator and the wiggler were shimmed by using the 'Magic Fingers' at the ends with a special algorithm. This paper reports the procedure and the results of the measurement and the optimization for the field integrals.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB012  
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SUPSS102
 Vibrating Wire Measurements for the XiPAF Permanent Magnet Quadrupoles  
TUPMB009   use link to access more material from this paper's primary paper code  
 
  • B.C. Wang, M.T. Qiu, Z.M. Wang
    State Key Laboratory of Intense Pulsed Radiation Simulation and Effect, Northwest Institute of Nuclear Technology, Shannxi, People's Republic of China
  • C.T. Du, X.W. Wang, L. Wupresenter, Q.Z. Xing, S.X. Zheng
    TUB, Beijing, People's Republic of China
  
  Vibrating wire technique is a promising measure-ment method for small-aperture Permanent Magnet Quadrupoles (PMQs) in linear accelerators and scan-ning nuclear microprobes. In this paper, we describe the improved vibrating wire setup for measuring an individual PMQ with the minimum aperture of several millimeters. This setup is aiming at measuring the magnetic center. The advantage of this setup is that any mechanical measurement on the wire, which may be the main error source, is avoided. Experiments of the 20 mm-aperture Halbach-type PMQs for Xi'an Proton Application Facility (XiPAF) DTL has been carried out. The research results of the magnetic center measurements show a precision of about 10 μm and robustness against the background magnetic field. Results of the magnetic center and field multipoles measurements agree with the ones obtained from the rotating coil.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB009  
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SUPSS103
 Compact Rare-Earth Permanent Magnet Material System for Industrial Electron Accelerators Irradiation Field Formation  
TUPMB015   use link to access more material from this paper's primary paper code  
 
  • D.S. Yurov, A.N. Ermakov, V.V. Khankin, N.V. Shvedunov, V.I. Shvedunov
    M.V. Lomonosov Moscow State University (MSU), Skobeltsyn Institute of Nuclear Physics, Moscow, Russia
  
  A compact system for industrial electron accelerators irradiation field formation is described. This system permits to get uniform distribution of electron beam current along the direction perpendicular to product movement with the width 50 - 100 cm. Its main element is a non-linear quadrupole lens, based on rare-earth permanent magnet material. This system can be used instead of an electromagnet of the conventional beam scanning systems, making much more comfortable conditions for products irradiation. Operation principles, results of calculations and test results of the system for CW 1 MeV and pulse 10 MeV electron linear accelerators are described.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPMB015  
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SUPSS104
 Data Mining Applied in Management of Heavy Ion Accelerator Power Supplies  
THPMW009   use link to access more material from this paper's primary paper code  
 
  • H. Zhang, D.Q. Gao, Q.S. Qian, P. Sun
    IMP/CAS, Lanzhou, People's Republic of China
  
  Scientific and effective management of power supplies could reduce the failure rate and improve the efficiency of the heavy ion accelerator. This paper shows how to introduce data mining into the intelligent management of heavy ion accelerator power supplies. A web site platform was developed to collect raw data. The raw data includes many kinds of information about one power supply's life cycle form its development to operation. Among which the failure records are particularly important. According to the attribute that the records are mostly nominal data, R software and SQL Server 2008 Business Intelligence Development Studio were chose as mining tools. R soft-ware was used to carry on the statistical characteristic analysis and SQL Server 2008 Business Intelligence Development Studio was used to find out association rules. Useful conclusions have been drawn. This work has laid a solid foundation to further establish the intelligent management system of heavy ion accelerator power supplies.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW009  
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SUPSS105
 The RF Design of a Compact, High Power Pulse Compressor with a Flat Output Pulse  
THPMW022   use link to access more material from this paper's primary paper code  
 
  • P. Wang, H.B. Chen, J. Shi
    TUB, Beijing, People's Republic of China
  • I. Syratchev, W. Wuensch, H. Zha
    CERN, Geneva, Switzerland
  
  An X-band, high-power pulse compressor, which can produce a flat pulse and a power gain of 4.3, has been designed. The device is compact, with the dimensions of within 1m, and is designed for CLIC first energy stage based on klystrons. We also discuss about a two stage pulse compressor with power gain of 9.18, which may be a candidate of the X-FEL using CLIC X-band linacs and klystrons with low peak power.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW022  
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SUPSS106
 Simulation of an Accelerator Pulse Power Supply with an Active Rectifier Using SIMPLORER  
THPMW023   use link to access more material from this paper's primary paper code  
 
  • F.J. Wu, D.Q. Gao, M. Li
    IMP/CAS, Lanzhou, People's Republic of China
  
  In this paper, a simulation model of an accelerator pulse power supply with an active rectifier (voltage-type SVPWM rectifier) was set up based on the C-Model function in SIMPLORER 8.1, which is a simulation software belonging to the ANSOFT corporation. We introduce a SVPWM rectifier into an accelerator pulse power supply to solve its problems such as low input power factor, a large number of AC current harmonics and instable DC bus voltage due to the diode or thyristor rectifier used in it now. Components of control strategies developed in C language were built up and inserted into the simulation project. The simulation results indicate that an accelerator pulse power supply with a SVPWM rectifier can solve the problems above well. For all the control strategies were developed in C language, they can be transplanted into the digital signal processor (DSP) nearly without change for the prototype controlling. So it provides a basis for development of the experimental prototype.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMW023  
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SUPSS107
 The Hiradmat 27 Experiment: Exploring High-Density Materials Response at Extreme Conditions for Antiproton Production  
THPMY023   use link to access more material from this paper's primary paper code  
 
  • C. Torregrosa, M. Bergeret, E. Berthomé, M.E.J. Butcher, M. Calviani, L. Gentini, D. Horvath, J. Humbert, A. Perillo-Marcone, G. Vorraro
    CERN, Geneva, Switzerland
  • C. Torregrosa
    UPV, Valencia, Spain
  
  The HRMT27-Rodtarg- experiment used the HiRadMat facility at CERN to impact intense 440 GeV proton beams onto thin rods -8 mm diameter, 140 length- made of high-density materials such as Ir, W, Ta, Mo among others. The purpose of the experiment has been to reduce uncertainties on the CERN antiproton target material response and assess the material selection for its future redesign. The experiment was designed to recreate the extreme conditions reached in the named target, estimated on an increase of temperature above 2000 °C in less than 0.5 μs and a subsequent compressive-to-tensile pressure wave of several GPa. The goals of the experiment were to validate the hydrocode calculations used for the prediction of the antiproton target response and to identify limits and failure mechanisms of the materials of interest. In order to accomplishing these objectives, the experiment counted on extensive online optical instrumentation pointing at the rod surfaces. Online results suggest that most of the targets suffer important internal damage even from conditions seven times lower than the reached in the AD-target. Tantalum targets clearly showed the best dynamic response.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPMY023  
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SUPSS108
 Hall Element Relative Position and Angle Calibrations for the Cryogenic Permanent Magnet Undulator  
WEPMR048   use link to access more material from this paper's primary paper code  
 
  • L. Gong, W. Chen, W. Kang, L.Z. Li, H.H. Lu, Y.F. Yang
    IHEP, Beijing, People's Republic of China
  
  A three dimensions Hall probe will be manufactured for characterizing the magnetic performance of Cryogenic Permanent Magnet Undulator (CPMU) of Chinese High Energy Photon Source and the test facility (HEPS-TF) at Institute of High Energy Physics (IHEP). The positional and angular misalignment errors of the Hall sensors play an important role in the measurement accuracy of CPMU. In order to minimize the misalignment errors, a method of calibrating relative displacements and assembly angles of a 3-D Hall probe is carried out. In this paper, details of the calibration procedures and the data processing are presented.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR048  
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SUPSS110
 Development of a Compact X-Band Electron Linac for Production of Mo-99/Tc-99m  
TUPOY007   use link to access more material from this paper's primary paper code  
 
  • J. Jang
    The University of Tokyo, Tokyo, Japan
  • M. Uesaka
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
  • M. Yamamoto
    Accuthera Inc., Kawasaki, Kanagawa, Japan
  
  In response to the need of alternatives to the exhausted research reactors supplying Mo-99/Tc-99m, we are developing a compact X-band electron linear accelerator (linac). As an initial step, beam dynamics simulations were performed and electron beams of 35 MeV and 9.1 kW were obtained. We expect that sixteen linacs having these beam parameters can cover the demand of Tc-99m radiopharmaceuticals in Japan. On the other hand, we found that the combination of X-band RF and high beam power can give rise to instability of beam loading. We will therefore adjust and optimize the beam power while keeping Mo-99 production efficiency as high as possible.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY007  
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SUPSS111
 Novel Approach to Utilize Proton Beams from High Power Laser Accelerators for Therapy  
TUPOY003   use link to access more material from this paper's primary paper code  
 
  • U. Masood, M. Baumann, W. Enghardt, L. Karsch, J. Pawelke, S. Schürer
    OncoRay, Dresden, Germany
  • M. Baumann
    German Cancer Research Center (DKFZ), Heidelberg, Germany
  • M. Baumann
    German Cancer Consortium (DKTK), Dresden, Germany
  • T.E. Cowan, U. Schramm
    Technische Universität Dresden, Dresden, Germany
  • T.E. Cowan, W. Enghardt, T. Herrmannsdoerfer, J. Pawelke, U. Schramm
    HZDR, Dresden, Germany
  • K.M. Hofmann, J.J. Wilkens
    Technische Universität München, Klinikum rechts der Isar & Physics Department, Munich, Germany
  • F. Kroll
    Helmholtz-Zentrum Dresden-Rossendorf (HZDR), Institute of Radiation Physics, Dresden, Germany
  
  Funding: Supported by German BMBF, nos. 03Z1N511 and 03Z1O511 & DFG cluster of excellence MAP.
Protons provide superior radiotherapy benefits to patients, but immense size and cost of the system limits it to only few centers worldwide. Proton acceleration on μm scale via high intensity laser is promising to reduce size and costs of proton therapy, but associated beamlines are still big and massive. Also, in contrast to conventionally accelerated quasi-continuous mono-energetic pencil beams, laser-driven beams have distinct beam properties, i.e. ultra-intense pico-sec bunches with large energy spread and large divergences, and with low repetition rate. With new lasers with petawatt power, protons with therapy related energies could be achieved, however, the beam properties make it challenging to adapt them directly for medical applications. We will present our compact beamline solution including energy selection and divergence control, and a new beam scanning and dose delivery system with specialized 3D treatment planning system for laser-driven proton beams. The beamline is based on high field iron-less pulsed magnets and about three times smaller than the conventional systems*, and can provide high quality clinical treatment plans**.
* U. Masood et al, Applied Phys B, 117(1):41-52, 2014
** K.M. Hofmann et al, Medical Physics, 42(9):5120-5129, 2015 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY003  
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SUPSS112
 The Use of Cyclotron for PET/CT Scan in Indonesian Hospitals and Future Collaboration  
TUPOY005   use link to access more material from this paper's primary paper code  
 
  • N.S. Risdianto, J. Purwanto, F.A. Rahmadi
    Universitas Islam Negeri Sunan Kalijaga, Yogyakarta, Indonesia
  • N. Risdiana
    UMY, Yogyakarta, Indonesia
  
  In Indonesia there are only three hospitals, which using cyclotrons for cancer detection (PET scans). These three hospitals are located in one place: Jakarta. With 1.4 percent of the Indonesian population are developing tumor/cancer, compared to the number of hospitals, which have advanced PET technology from cyclotrons, it will be a major task for the government to empower the production and overseas collaboration in the cyclotron industry.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY005  
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SUPSS113
 Studies on Electron Linear Accelerator System for Polymer Research  
TUPOY039   use link to access more material from this paper's primary paper code  
 
  • E. Kongmon
    IST, Chiang Mai, Thailand
  • N. Kangrang
    Chiang Mai University, PBP Research Facility, Chiang Mai, Thailand
  • S. Rimjaem, J. Saisut, C. Thongbai
    Chiang Mai University, Chiang Mai, Thailand
  • P. Wichaisirimongkol
    Chiang Mai University, Science and Technology Research Institute, Chiang Mai, Thailand
  
  This research focuses on modification of an elec-tron linear accelerator system for irradiation of natural rubber latex and polymeric materials at the Plasma and Beam Physics Research Facility, Chiang Mai Universi-ty, Thailand. This is in order to study the change of material properties due to electron beam irradiation. The main accelerator system consists of a DC thermi-onic electron gun and a short standing-wave linac. This system will be able to produce electron beams with variable energy in the range of 0.5 to 4 MeV. The linac macro pulse frequency is adjustable within the range of 20 to 1000 Hz. The macro pulse duration is 4 μs. The electron pulse current can be varied from 10 to 100 mA. This lead to the electron dose of about 0.44 to 4.4 Gy-m2/min. In this paper, overview of the accelera-tor and the irradiation system is presented. Results of low-level RF measurements of the accelerating struc-ture are also reported and discussed.
This work has been supported by the CMU Junior Research Fellowship Program, the Department of Physics and Material Science, Faculty of science, Chiang Mai University. 		 
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY039  
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SUPSS114
 Geant4 Simulations of Proton-induced Spallation for Applications in ADSR Systems  
TUPOY019   use link to access more material from this paper's primary paper code  
 
  • S.C. Lee
    IIAA, Huddersfield, United Kingdom
  • C. Bungau, R. Cywinski
    University of Huddersfield, Huddersfield, United Kingdom
  
  Neutron spallation is an efficient process for producing intense neutron fluxes that can be exploited in Accelerator Driven Subcritical Reactors (ADSRs) for energy production and the transmutation of nuclear waste. In order to assess the feasibility of spallation driven fission and transmutation we have simulated proton induced neutron production using GEANT4, initially benchmarking our simulations against published experimental neutron spectra produced from a thick lead target bombarded with 0.5 and 1.5 GeV protons. The Bertini and INCL models available in GEANT4, coupled with the high precision (HP) neutron model, are found to adequately reproduce the published experimental data. Given the confidence in the GEANT4 simulations provided by this benchmarking we have then proceeded to simulate neutron production as a function of target geometry and thence to some preliminary studies of neutron production in an ADSR with a geometry similar to that of the proposed Belgian MYRRHA project. This paper presents the results of our GEANT4 benchmarking and simulations.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-TUPOY019  
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SUPSS115
 Design of an RF Device to Study the Multipactor Phenomenon  
MOPMW044   use link to access more material from this paper's primary paper code  
 
  • D. Amorim
    Grenoble-INP Phelma, Grenoble, France
  • J.-M. De Conto, Y. Gómez Martínez
    LPSC, Grenoble Cedex, France
  
  Multipacting is a parasitic electron avalanche process that may occur in RF devices such as cavities or couplers. As it can be detrimental to the operation of these devices, the accelerator group at LPSC is currently designing a coaxial resonant cavity in order to study this phenomenon. In order to determine the measurable parameters on the cavity, calculations were performed and validated with numerical simulations. In a second time multipacting simulations were conducted to determine if the experiment will allow to observe multipacting.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-MOPMW044  
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SUPSS116
 Studies on the Field Dependence of the BCS Surface Resistance  
WEPMR028   use link to access more material from this paper's primary paper code  
 
  • J.T. Maniscalco, D. Gonnella, G.H. Hoffstaetter, P.N. Koufalis, M. Liepe
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Experiments have shown that the temperature-dependent portion of the RF surface resistance of SRF materials also exhibits a dependence on the magnitude of the surface field, manifested as a "Q-slope" or "anti-Q-slope" in the medium field region. Recent theoretical work proposes an explanation of the anti-Q-slope in dirty-limit superconductors. In this report, we compare theoretical predictions with the results of systematic experimental studies on the RF field dependence of the surface resistance using 1.3 GHz niobium SRF cavities with a wide range of mean free paths. We find very good agreement between theory and experiment in the dirty limit, with some divergence as the cavities approach the clean limit.  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-WEPMR028  
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SUPSS117
 Demonstration of the Hollow Channel Plasma Wakefield Accelerator  
THPPA01   use link to access more material from this paper's primary paper code  
 
  • S.J. Gessner, J.M. Allen, C.I. Clarke, J.-P. Delahaye, J.T. Frederico, S.Z. Green, C. Hast, M.J. Hogan, N. Lipkowitz, M.D. Litos, B.D. O'Shea, D.R. Walz, V. Yakimenko, G. Yocky
    SLAC, Menlo Park, California, USA
  • E. Adli, C.A. Lindstrøm
    University of Oslo, Oslo, Norway
  • W. An, C.E. Clayton, C. Joshi, K.A. Marsh, W.B. Mori, N. Vafaei-Najafabadi
    UCLA, Los Angeles, California, USA
  • S. Corde, A. Doche
    LOA, Palaiseau, France
  • W. Lu
    TUB, Beijing, People's Republic of China
  
  Funding: Work supported by DOE contract DE-AC02-76SF00515.
Over the past decade, there has been enormous progress in the field of beam and laser-driven plasma acceleration of electron beams. However, in order for plasma wakefield acceleration to be useful for a high-energy e+e- collider, we need a technique for accelerating positrons in plasma as well. This is a unique challenge, because the plasma responds differently to electron and positron beams, with plasma electrons being pulled through the positron beam and creating a non-linear focusing force. Here, we demonstrate a technique called hollow channel acceleration that symmetrizes the wakefield response to beams of either charge. Using a transversely shaped laser pulse, we create an annular plasma with a fixed radius of 200 μm. We observe the acceleration of a positron bunch with energies up to 33.4 MeV in a 25 cm long channel, indicating an effective gradient greater than 100 MeV/m. This is the first demonstration of a technique that way be used for staged acceleration of positron beams in plasma. 		 
slides icon Slides SUPSS117 [5.647 MB]  
DOI • reference for this paper ※ DOI:10.18429/JACoW-IPAC2016-THPPA01  
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