Keyword: resonance
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MOBD3 Development of a 9 MHz 15 kW Solid-state CW Amplifier for RHIC impedance, network, cavity, feedback 67
 
  • S.C. Dillon
    Tomco Technologies, Stepney, South Australia, Australia
  
  This paper describes the technical details of the development of a high-power solid-state amplifier for Brookhaven Laboratory. The amplifier must withstand short duration events of 100% full-power reflection, and also must guarantee delivery of continuous power into any load impedance at any angle.  
slides icon Slides MOBD3 [10.800 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOBD3  
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MOPWA005 Comparison between Digital Filters and Singular Value Decomposition to Reduce Noise in LHC Orbits used for Action and Phase Jump Analysis simulation, quadrupole, collider, hadron 83
 
  • A.C. García-Bonilla, J.F. Cardona
    UNAL, Bogota D.C, Colombia
  
  Funding: Fundación Para la Promoción de la Investigación y la Tecnología del Banco de la República and DIB (División de Investigación de Bogotá).
One of the initial difficulties to apply the Action and Phase Jump (APJ) analysis to LHC orbits was the high level of noise present in the BPM measurements. On the other hand, the unprecedented number of turns for LHC allows us to use all sort of filters. In this paper, we evaluate the effectiveness of digital filters like the band-pass filter and compare them with a filter based on Singular Value Decomposition, when magnetic error estimations are made using a recent version of the APJ method. First, mainly results on simulated orbits with noise are presented, and then, plots and results are shown for the filters effect on experimental data. The analysis indicates that a combination of filters leads to measurements with the least uncertainty. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA005  
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MOPWA013 Modeling and Measurements of Spin Depolarization kicker, electron, polarization, synchrotron 109
 
  • N. Carmignani, F. Ewald, L. Farvacque, B. Nash, P. Raimondi
    ESRF, Grenoble, France
  
  An electron bunch in a storage ring becomes spin polarized due to the Sokolov-Ternov effect. The beam may then be depolarized by applying a horizontal magnetic field oscillating in resonance with the spin tune. This technique has been used to measure the electron energy at numerous synchrotrons. In this paper, we report on modeling and measurements of the polarization and depolarization process at the ESRF. We report the results of a Matlab based parallelized spin tracking code that we developed for these studies. We show the change in depolarization resulting as different physical effects are added to the model.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA013  
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MOPWA016 Increasing the Dynamic and Momentum Apertures of the ThomX Ring by Means of Octupole Correctors sextupole, octupole, multipole, dipole 121
 
  • J.F. Zhang, P. Bambade, A. Faus-Golfe, H. Monard
    LAL, Orsay, France
  • A. Faus-Golfe
    IFIC, Valencia, Spain
  • A. Loulergue
    SOLEIL, Gif-sur-Yvette, France
  
  Funding: Work is supported by ANR-10- EQPX-51 and ANR-11-IDEX-0003-02, and also by grants from Region Ile-de-France.
The electron ring of the compact Compton-backscattering X-ray source ThomX which is being built at LAL featured with a small circumference of 18 meters and a low beam energy 50-70 MeV, and its long term single particle dynamics is dominated by the non linear effects in the transverse and longitudinal planes. In this paper, we study the feasibilities to reduce the sextupole resonances and then increase the dynamic aperture and momentum aperture of the ThomX ring, using octupoles correctors. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA016  
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MOPWA020 Longitudinal Stability Of Short Bunches in Storage Rings with Strong Longitudinal Focusing impedance, synchrotron, dipole, simulation 135
 
  • P. Kuske
    HZB, Berlin, Germany
  
  Funding: work supported by the BMBF
In the BESSY VSR project, the variable bunch length storage ring, two high gradient accelerating structures at 1.5 and 1.75 GHz will be phased such that long and short bunches can be stored simultaneously. The longitudinal stability of the short bunches is investigated taking into account the shielded CSR- and a purely inductive impedance. Multi particle tracking studies and numerical solutions of the Vlasov-Fokker-Planck equation show that threshold currents for short bunches do not follow the simple scaling law which was found for long bunches. The inductive impedance can even lower the thresholds for the instability. With an 80 times increased accelerating gradient and reasonable assumptions on the inductive impedance for shorter bunches stable operation can be expected with bunches 1.8 ps long (RMS-value) and 0.8 mA current. According to the calculations and operating in a dedicated low-α mode will produce stable 40 μA bunches with 400 fs length 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA020  
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MOPWA021 Transverse Resonance Island Buckets at the MLS and BESSY II operation, radiation, electron, photon 138
 
  • M. Ries, J. Feikes, T. Goetsch, P. Goslawski, J. Li, M. Ruprecht, A. Schälicke, G. Wüstefeld
    HZB, Berlin, Germany
  
  By operating the Metrology Light Source (MLS) near horizontal resonances (fx/frev=1/2, 1/3 or 1/4), two, three or four resonance island buckets may be populated for beam storage. This paper presents experimental results and operational experience such as tuning the machine for high current, controlling inter-bucket diffusion rates, improving overall lifetime and extraction of radiation pulses with sub-revolution repetition rate. First approaches to transfer this mode of operation to the BESSY II storage ring will also be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA021  
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MOPWA027 Generic Settings Generation for FAIR: First Experience at SIS18 framework, controls, operation, cavity 156
 
  • D. Ondreka, J. Fitzek, H. Liebermann, R. Müller
    GSI, Darmstadt, Germany
  
  The accelerators of the FAIR facility will be operated using a new control system presently under design at GSI. One of its major components, the module for settings generation and management, is based on the framework LSA developed at CERN. Its task is the provision and administration of set values for all devices in the FAIR facility. The set values for any accelerator are derived from a machine model, implemented by accelerator physicists using the features of the LSA framework. In view of the large number of accelerators in the FAIR facility, the aim is to develop a generic model, applicable to any of those machines. This requires the introduction of an additional logical layer on top of the LSA framework, ensuring the coherence of the modeling strategy across all accelerators. Following this design concept, a prototype of the FAIR settings management system has been realized at GSI, providing support for a large number of operation modes relevant for the later operation of FAIR. The prototype has been used extensively during recent machine experiments with the synchrotron SIS18, performed both to benchmark the machine model and to support further machine developments for FAIR.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA027  
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MOPWA028 Resonance Compensation for High Intensity Bunched Beams space-charge, sextupole, ion, controls 159
 
  • G. Franchetti, S. Aumon, F. Kesting, H. Liebermann, C. Omet, D. Ondreka, R. Singh
    GSI, Darmstadt, Germany
  
  Mitigation of periodic resonance crossing induced by space charge is foreseen  via classic resonance compensation. The effect of the space charge is, however,  not obvious on the effectiveness on the compensation scheme.  In this proceeding we report on an experimental campaign performed at SIS18  in an attempt to investigate experimentally the effect of space charge on the resonance  compensation. The experimental results and their consequences are discussed  through numerical simulations.   
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA028  
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MOPWA055 Study of Emittance Growth Caused by Space Charge and Lattice Induced Resonances space-charge, lattice, emittance, synchrotron 245
 
  • K. Ohmi
    KEK, Ibaraki, Japan
  
  Resonance strength and resonance width induced by space charge and lattice nonlinearity is discussed with integrals along a ring like the radiation integrals. Emittance growth is evaluated by model with the resonance width to understand the mechanism. The results are compared with fully PIC simulations.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWA055  
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MOPJE035 An Extended SPS Longitudinal Impedance Model impedance, vacuum, kicker, simulation 360
 
  • J.V. Campelo, T. Argyropoulos, T. Bohl, F. Caspers, J. F. Esteban Müller, J.B. Ghini, A. Lasheen, D. Quartullo, B. Salvant, E.N. Shaposhnikova, C. Zannini
    CERN, Geneva, Switzerland
  
  Longitudinal multi-bunch instability in the CERN SPS with a very low intensity threshold is a serious limitation for the future doubling of bunch intensity required by Hi-Lumi LHC project. A complete and accurate impedance model is essential to understand the nature of this instability and to plan possible cures. This contribution describes in detail the current longitudinal impedance model of the SPS. Recently, the model was updated with new findings and includes now the impedance of accelerating cavities, kicker and septum magnets, beam position monitors, vacuum Flanges, shielded and unshielded pumping ports, electrostatic septa and resistive wall. Electromagnetic simulations and bench measurements were used to build the model. The contribution from each element is described and compared to the total machine impedance. Together with relevant beam measurements and simulations, the analysis of the different sources of impedance is used to identify the source of the longitudinal instability limiting the SPS performance so that the responsible elements can be acted upon.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE035  
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MOPJE036 Longitudinal Impedance Characterization of the CERN SPS Vacuum Flanges impedance, vacuum, simulation, damping 363
 
  • J.V. Campelo
    CERN, Geneva, Switzerland
  
  This contribution describes the thorough studies carried out to characterize the longitudinal impedance of the CERN SPS vacuum flanges, which are believed to be the main source of LHC beam instability. Around 500 high-impedance flanges of 8 different types have been identified. Three factors play an important role in the characterization of these flanges: the type of vacuum chambers that the flange interconnects, whether or not both sides are electrically isolated (by means of an enamel coating) and, finally, the presence of damping resistors which damp high-Q resonances. Not only, full-wave electromagnetic field simulations, but also RF measurements have been used to evaluate the impedance of these elements. The R/Q of the relevant resonances was measured using the well-known bead-pull technique. In particular, a subset of around 150 flanges has been found to be the source of a high-impedance resonance at 1.4 GHz, also observed in beam measurements. Guidelines on how to reduce the impedance of these elements are also presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE036  
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MOPJE037 Study and Comparison of Mode Damping Strategies for the UA9 Cherenkov Detector Tank damping, cavity, vacuum, detector 366
 
  • A. Danisi, F. Caspers, R. Losito, A. Masi, B. Salvant, C. Vollinger
    CERN, Geneva, Switzerland
  • T. Demma, P. Lepercq
    LAL, Orsay, France
  
  In the framework of the UA9 experiment, the Cherenkov detector is useful to measure the amount of particles deflected by a bent crystal, proving the crystal collimation principle. The tank used to host this device is taken as a case study for an in-depth analysis of different damping strategies for electromagnetic modes which otherwise would give rise to important beam-coupling impedance contributions. Such strategies involve the use of ferrite, damping resistors and a mode-coupler, a solution which intercepts the modes inside the cavity but damps the related power outside the vacuum tank (potentially avoiding heating). Such solutions are discussed through experimental measurements and the relative quality factor is taken as a figure of merit.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE037  
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MOPJE045 Fixed Points in Presence of Space Charge in Circular Particle Accelerators space-charge, vacuum, simulation, extraction 389
 
  • M. Giovannozzi, S.S. Gilardoni, A. Huschauer
    CERN, Geneva, Switzerland
  • S. Machida, C.R. Prior, S.L. Sheehy
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  
  Recent measurements performed in the framework of the multi-turn extraction (MTE) studies showed a dependence of the position of beamlets obtained by crossing a stable transverse resonance on the total beam intensity. This novel observation has triggered a number of studies aiming at understanding the source of the observed effect. In this paper the results of numerical simulations performed in different conditions are discussed in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE045  
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MOPJE046 Influence of the Alignment of the Main Magnets on Resonances in the CERN Proton Synchrotron synchrotron, alignment, proton, operation 392
 
  • A. Huschauer, S.S. Gilardoni, R. Wasef
    CERN, Geneva, Switzerland
  
  During the Long Shutdown 1 seven out of the one hundred combined function PS main magnets were removed from the tunnel to conduct maintenance. After reinstallation, the main magnets were aligned to the reference positions and within the first week of operation of the accelerator, a beam-based re-alignment campaign was performed to reduce the excursions of the closed orbit. In order to further investigate and understand the source of betatronic resonances, which, already in 2011, were found to be excited by the bare machine, tune diagram measurements before and after this beam-based magnet alignment were conducted. In both cases the same resonances as in 2011 were found to be present; however, after the alignment, an overall increase of their strengths was observed. In this paper we present the corresponding measurement results and discuss the direct impact on the daily operation of the accelerator.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE046  
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MOPJE048 Electron-Cloud Studies for Transversely Split Beams electron, simulation, injection, extraction 399
 
  • N. Pradhan, S.S. Gilardoni, M. Giovannozzi, G. Iadarola, G. Rumolo
    CERN, Geneva, Switzerland
  • N. Pradhan
    UMiss, University, Mississippi, USA
  
  Recently, resonance crossing has been proposed as a means of manipulating the transverse beam distribution. This technique has application, among other topics, to injection and extraction schemes. Moreover, the transversely split beams might also be used as a mitigation measure of electron-cloud effects. The results of detailed numerical simulations are discussed in this paper, possibly opening new options for scrubbing of beam pipes in circular accelerators.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE048  
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MOPJE052 Observations of an Anomalous Octupolar Resonance in the LHC simulation, dipole, betatron, hadron 412
 
  • F.S. Carlier, J.M. Coello de Portugal, A. Langner, E.H. Maclean, T. Persson, R. Tomás, R. Westenberger
    CERN, Geneva, Switzerland
  
  While linear LHC dynamics is mostly understood and under control, non-linear beam dynamics will play an increasingly important role in the challenging regimes of future LHC operation. In 2012, turn-by-turn measurements of large betatron excitations of LHC Beam 2 at injection energy were carried out. These measurements revealed an unexpectedly large spectral line in the horizontal motion with frequency Qx+2Qy. Detailed analyses and simulations are presented to unveil the nature of this spectral line.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE052  
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MOPJE074 Optimizing SLS-2 Nonlinearities Using a Multi-Objective Genetic Optimizer sextupole, optics, octupole, injection 486
 
  • M.P. Ehrlichman, M. Aiba, A. Streun
    PSI, Villigen PSI, Switzerland
  
  An upgrade to the SLS is currently under development. This upgrade will likely utilize the same hall and same machine circumference, 288 m, of the SLS. Achieving a sufficiently low emittance with such a small circumference requires tight focusing and low dispersion. These conditions make chromaticity correction difficult and minimization of 1st and 2nd order non-linear driving terms does not yield sufficient dynamic aperture and Touschek lifetime. In this proceeding, we discuss the multi-objective genetic optimization method being implemented at SLS to aid the design of a chromaticity correction scheme for SLS2.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE074  
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MOPJE079 Tracking Studies in the LHeC Lattice lattice, proton, dynamic-aperture, electron 502
 
  • E. Cruz Alaniz, D. Newton
    The University of Liverpool, Liverpool, United Kingdom
  • E. Cruz Alaniz, D. Newton
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • R. Tomás
    CERN, Geneva, Switzerland
  
  Funding: This project has received funding from the European Union’s Seventh Framework Programme for research, technological development and demonstration under grant agreement no 289485
The Large Hadron Electron Collider (LHeC) is a proposed upgrade of the LHC to provide electron-proton collisions and explore a new regime of energy and luminosity for nucleon-lepton scattering. A nominal design has previously been presented, featuring a lattice and optical configuration to focus one of the proton beams of the LHC (reaching a value of β*=10 cm) and to collide it head-on with an electron beam to produce collisions with the desired luminosity of L=1033 cm-2 s-1. The proton beam optics is achieved with the aid of a new inner triplet of quadrupoles at L*=10 m from the interaction point and the extension of the Achromatic Telescopic Squeezing (ATS) Scheme used for the High Luminosity-LHC project. The flexibility of this design has been studied in terms of minimising β* and increasing L*. In this work, particle tracking is performed in a thin lens approximation of the LHeC proton lattice to compute the dynamic aperture and perform frequency map analysis for different types of chromatic correction schemes, in order to find the one who will provide the most beam stability and to study the effects of non linearities. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPJE079  
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MOPMA013 Experience with Round Beam Operation at the Advanced Photon Source coupling, emittance, operation, storage-ring 562
 
  • A. Xiao, L. Emery, V. Sajaev, B.X. Yang
    ANL, Argonne, Ilinois, USA
  
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357
Very short Touschek lifetime becomes a common issue for next-generation ultra-low emittance storage ring light sources. In order to reach a longer beam lifetime, such a machine often requires operating with a vertical-to-horizontal emittance ratio close to an unity, i.e. a ‘‘round beam''. In tests at the APS storage ring, we determined how a round beam can be reached experimentally. Some general issues, such as beam injection, optics measurement and corrections, and orbit correction have been tested also. To demonstrate that a round beam was achieved, the beam size ratio is calibrated using beam lifetime measurement. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMA013  
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MOPMN029 Spin Resonance Strength Calculation Through Single Particle Tracking for Rhic betatron, proton, lattice, emittance 763
 
  • Y. Luo, Y. Dutheil, H. Huang, F. Méot, V.H. Ranjbar
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The strengths of spin resonances for the polarized-proton operation in the Relativistic Heavy Ion Collider are currently calculated with code DEPOL, which numerically integrate through the whole ring based on analytical approximate formula. In this article, we calculate the spin resonance strength by performing Fourier transformation to the actual transverse magnetic field seen by a single particle travelling through the ring. Comparison is made between the results from this method and DEPOL and other approaches. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN029  
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MOPMN030 Proton Spin Tracking with Symplectic Integration of Orbit Motion proton, closed-orbit, ion, sextupole 766
 
  • Y. Luo, Y. Dutheil, H. Huang, F. Méot, V.H. Ranjbar
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Symplectic integration for orbital motion had been adopted in SimTrack which has been extensively used for dynamic aperture calculation with beam-beam interaction for the Relativistic Heavy Ion Collider (RHIC). Recently spin tracking for protons has been implemented on top of the orbit motion in this code. In this article, we will explain the implementation of spin motion using Thomas-BMT equation, and benchmark with other spin tracking codes currently used for RHIC. Possibility and remedy for very-long term particle tracking, such as on the RHIC energy acceleration, is also explored. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPMN030  
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MOPHA001 Transverse Bunch by Bunch Feedback Operations at the Australian Synchrotron Light Source feedback, operation, storage-ring, synchrotron 769
 
  • R.T. Dowd, M.P. Atkinson, M.J. Boland, G. LeBlanc, Y.E. Tan, K. Zingre
    SLSA, Clayton, Australia
  
  The Australian Synchrotron light source has recently put in operation its transverse bunch-by-bunch feedback system during user beam mode. Getting to the stage of stable operation has been a long road and this paper will outline the many difficulties that were encountered. Chief among these are the apparent strong, high frequency, vertical resonances that appear when the storage ring's three in-vacuum undulators are closed to specific gaps. The behaviour of these resonances and their effects on achieving stable feedback operation will be explored in detail.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA001  
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MOPHA014 Magnetic Field Parametrization for Efficient Spin Tracking with POLE lattice, closed-orbit, quadrupole, simulation 808
 
  • J.F. Schmidt, W. Hillert
    ELSA, Bonn, Germany
  
  Funding: BMBF
The new spin dynamics simulation suite pole is designed to perform systematic studies of beam depolarization in circular accelerators with short storage times or fast energy ramps. It is based on spin tracking using a Runge-Kutta algorithm with adaptive step width. pole can approximate the magnetic fields of the accelerator with a Fourier series to reduce computing time. Therefore, the magnetic field distribution is simplified with frequency filters by a C++ library before the spin tracking. The versatile library deals with import and export of lattices and particle trajectories from MAD-X and Elegant. The derived magnetic field distributions can be interpolated, Fourier transformed and accessed easily by applications. This contribution discusses advantages and disadvantages of the frquency filtering concept. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA014  
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MOPHA015 Measurement of Momentum Compaction Factor via Depolarizing Resonances at ELSA polarization, electron, extraction, experiment 811
 
  • J.F. Schmidt, W. Hillert, M. Schedler, J.-P. Thiry
    ELSA, Bonn, Germany
  
  Funding: DFG
Measuring beam depolarization at energies in close proximity to a depolarizing integer resonance is an established method to determine the beam energy of a circular accelerator. This technique offers high accuracy due to the small resonance widths. Thus, also other accelerator parameters related to beam energy can be measured based on this method. This contribution presents a measurement of the momentum compaction factor with a high precision of 10-4. It was performed at the 164 m stretcher ring of the Electron Stretcher Facility ELSA at Bonn University, which provides a polarized electron beam of up to 3.2 GeV. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA015  
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MOPHA033 Physical Parameter Identification of Cross-Coupled Gun and Buncher Cavity at REGAE gun, cavity, coupling, higher-order-mode 857
 
  • A.S. Nawaz, H. Werner
    TUHH, Hamburg, Germany
  • M. Hoffmann, S. Pfeiffer, H. Schlarb
    DESY, Hamburg, Germany
  
  A reasonable description of the system dynamics is one of the key elements to achieve high performance control for accelerating modules. This paper depicts the system identification of a cross-coupled pair of cavities for the Relativistic Electron Gun for Atomic Exploration - REGAE. Two normal conducting copper cavities driven by a single RF source accelerate and compress a low charge electron bunch with sub 10 fs length at a repetition rate up to 50 Hz. It is shown how the model parameters of the cavities and the attached radio frequency subsystem are identified from data generated at the REGAE facility.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPHA033  
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MOPWI015 A Low Time-Dispersion Refractive Optical Transmission Line for Streak Camera Measurements electron, experiment, database, plasma 1178
 
  • J.G. Power, G. Ha
    ANL, Argonne, Illinois, USA
  • G. Ha
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  
  Funding: Work supported by the U.S. Department of Energy office of High Energy Physics.
Streak camera measurements of the charge particle bunch length are limited in resolution due to several factors: (1) the light from the source (optical transition radiation, Cherenkov, synchrotron radiation, etc.); (2) time dispersion introduced in the optical transmission line between the source and the streak camera; and finally (3) the streak camera resolution. The limiting resolution usually arises from the optical transmission line. While an all-reflective transmission line can eliminate dispersion, the system is complicated and expensive. In this paper, we consider how to design a refractive optical transport line to minimize the time dispersion while maximizing the signal. We present a theoretical model of the dispersion, modeling, and measurements of the time dispersion for several different lens materials. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI015  
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MOPWI031 Microwave Modeling for Electron Cloud Density Measurements at CesrTA simulation, electron, synchrotron, storage-ring 1227
 
  • J.P. Sikora, Y. Li
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  • S. De Santis
    LBNL, Berkeley, California, USA
  
  Funding: This work is supported by the US National Science Foundation PHY-0734867, PHY-1002467, and the US Department of Energy DE-FC02-08ER41538, DE-SC0006505.
The electron cloud (EC) density in accelerator beam-pipe has been measured using resonant microwaves. The resonances are produced by changes in beam-pipe geometry that generate reflections and standing waves, with typical behavior being similar to a section of waveguide with shorted ends. The technique uses fact that the EC density will shift the resonant frequencies. In previous analysis, we have made the simplifying approximation that the standing waves are multiples of a half-wavelength and that the magnitude of the electric field is symmetric about the longitudinal center of the resonance. In this paper we show that some changes in beam-pipe geometry will result in asymmetric electric field magnitudes along the resonant length. When this is combined with an EC density that varies along this length, the magnitude of the frequency shift will be altered. We present our initial attempt to correct for this effect by modeling the existing beam-pipe using CST Microwave Studio(R) to obtain a more realistic electric field distribution. This correction is then applied to data taken with beam at several resonant frequencies. The measurements were made at the Cornell Electron Storage Ring (CESR), which has been reconfigured as a test accelerator (CesrTA) providing electron or positron beams ranging in energy from 2 to 5 GeV.
* http://dx.doi.org/10.1016/j.nima.2014.03.063 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-MOPWI031  
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TUAB1 Correction of Nonlinear Coupling Resonances in the SPring-8 Storage Ring coupling, injection, octupole, sextupole 1329
 
  • M. Takao, K. Fukami, Y. Shimosaki, K. Soutome
    JASRI/SPring-8, Hyogo-ken, Japan
  
  The correction of the lattice nonlinearity of the storage rings is crucial for the enlargement of the dynamic aperture of the storage rings, which in general leads to the higher injection efficiency and the longer lifetime. At the SPring-8 storage ring, it is realized that the higher order coupling resonances are considerably excited. After the usual correction of the nonlinear dynamics in terms of the normal sextupole magnets, we suppress one of the resonances by using the skew sextupole magnets for the purpose of further improving the dynamic aperture. As a result of the correction by the skew sextupoles, the reckoned improvement of the injection efficiency and the lifetime is achieved. Furthermore, at the SPring-8 storage ring, it is observed that the error magnetic field of a particular insertion device (ID) excites the higher nonlinear coupling resonance of the skew octupoles, which remarkably deteriorates the injection efficiency. In order to correct the coupling resonance, we have installed the octupole magnets at the ID, by which we restore the injection efficiency.  
slides icon Slides TUAB1 [3.275 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUAB1  
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TUAB3 Chromaticity Effects for Space Charge Dominated Beams in the CERN PS Booster space-charge, simulation, emittance, sextupole 1335
 
  • V. Forte
    Université Blaise Pascal, Clermont-Ferrand, France
  • E. Benedetto, F. Schmidt
    CERN, Geneva, Switzerland
  
  In view of the LHC Injectors Upgrade (LIU) project, an extensive campaign is on-going in the CERN PS Booster (PSB) to study collective effects for the future operation with the 160 MeV injection from Linac4. In operation, the machine is running with uncorrected natural chromaticity. This paper focuses on the study of the effects of chromaticity on losses and beam blow-up.  
slides icon Slides TUAB3 [4.887 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUAB3  
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TUPWA039 Transverse Gradient Undulator-Based High-Gain-FELs - a Parameter Study undulator, laser, electron, FEL 1502
 
  • A. Bernhard, V. Afonso Rodríguez, E. Burkard, A.-S. Müller, C. Widmann
    KIT, Karlsruhe, Germany
  
  Transverse gradient undulators (TGU) have recently been discussed as sources for High Gain Free Electron Lasers (FEL) driven by electron beams with an elevated energy spread as for example generated in storage rings or wakefield accelerators. In this contribution we present the results of a parameter study based on the one-dimensional TGU-FEL theory making realistic assumptions on the key parameters achievable for the transverse gradient undulator. We show for which parameter areas LWFA-driven TGU-FELs are virtually technically feasible today and which technical improvements would be required to employ the concept for a laboratory-scale X-Ray FEL.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWA039  
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TUPJE033 A Research on the Reverse Tapering Method to Gain High Power Polarized Photon Beam with Fixed Wavelength undulator, radiation, electron, simulation 1678
 
  • C.H. Shim, I.S. Ko
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • J.H. Han, Y.W. Parc
    PAL, Pohang, Kyungbuk, Republic of Korea
  
  Polarization of soft X-ray photon can be controlled with combination between planar undulators and helical ones. We need to give a reverse tapering to the planar undulators to make microbunching in the electron beam while the linearly polarized radiation power is depressed. In this case, however, resonance wavelengths in each planar undulator are different each other. Therefore, proper initial undulator parameter and tapering strength parameter have to be chosen to obtain high power polarized photon beam with fixed wavelength. In this research, method for deciding suitable reverse tapering is presented using simulation results of PAL-XFEL soft X-ray case with 10 GeV electron beam energy.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE033  
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TUPJE050 Design of a Resonant Transition Radiation Source in the soft X-ray Range photon, radiation, electron, vacuum 1735
 
  • P. Wang, K.C. Leou
    NTHU, Hsinchu, Taiwan
  • N.Y. Huang, W.K. Lau, A.P. Lee
    NSRRC, Hsinchu, Taiwan
  
  Resonant transition radiation (RTR) can be generated from multi-layer structures when they are driven by relativistic electron beams. In consideration of using the NSRRC 90 MeV photoinjector as driver, we examined the feasibility of generating narrow-band soft x-rays from various multi-layer structures. Based on analytical theory, the expected angular-spectral distribution and photon yield of these radiators are calculated and compared.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE050  
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TUPJE070 Preliminary Experimental Investigation of Quasi Achromat Scheme at Advanced Photon Source lattice, emittance, operation, optics 1800
 
  • Y. Sun, H. Shang
    ANL, Argonne, Ilinois, USA
  
  Funding: Work supported by the U.S. Department of Energy, Office of Science, under Contract No. DE-AC02-06CH11357.
Next generation storage rings require weaker dipole magnets and stronger quadrupole focusing to achieve very low emittance. To suppress the geometric and chromatic optics aberrations introduced by the strong sextupoles, achromat and quasi achromat schemes are applied in the lattice design to improve the beam dynamics performance. In this paper, some preliminary experimental investigation of the quasi achromat scheme at the Advanced Photon Source (APS) are presented. Three different operation lattices are compared on their beam dynamics performance. Although none of these operation lattices achieve ideal quasi achromat condition, they have certain relevant features. It is observed that fewer resonances are present in the nominal operation lattice which is most close to quasi achromat required conditions. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPJE070  
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TUPHA013 Skew-Quad Parametric-Resonance Ionization Cooling: Theory and Modeling coupling, betatron, emittance, focusing 1993
 
  • A. Afanasev
    GWU, Washington, USA
  • Y.S. Derbenev, V.S. Morozov, A.V. Sy
    JLab, Newport News, Virginia, USA
  • R.P. Johnson
    Muons, Inc, Illinois, USA
  
  Funding: This work was supported in part by U.S. DOE STTR Grants DE-SC0005589 and DE-SC0007634.
Muon beam ionization cooling is a key component for the next generation of high-luminosity muon colliders. To reach adequately high luminosity without excessively large muon intensities, it was proposed previously to combine ionization cooling with techniques using a parametric resonance (PIC). Practical implementation of PIC proposal is a subject of this report. We show that an addition of skew quadrupoles to a planar PIC channel gives enough flexibility in the design to avoid unwanted resonances, while meeting the requirements of radially-periodic beam focusing at ionization-cooling plates, large dynamic aperture and an oscillating dispersion needed for aberration corrections. Theoretical arguments are corroborated with models and a detailed numerical analysis, providing step-by-step guidance for the design of Skew-quad PIC (SPIC) beamline. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPHA013  
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TUPTY070 Strong-Strong Simulations of Beta star Levelling for Flat and Round Beams luminosity, emittance, simulation, detector 2192
 
  • M.P. Crouch, R.B. Appleby
    UMAN, Manchester, United Kingdom
  • B.D. Muratori
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  
  Funding: STFC HL-LHC
The HL-LHC project aims to reach larger peak luminosities, however this can lead to a high pile up in the detectors. To control the pile up, luminosity levelling has been suggested. One proposed method is β*-luminosity levelling, in which beams collide at a larger than nominal β*. The β* is then reduced in steps as the beam intensity decays. This allows the luminosity to be kept constant over part of a physics fill. The use of round or flat optics will change the beam-beam effect of the head on collisions as well as the long range interactions. Here simulations of β* levelling are presented for the case of flat and round beam optics and the difference in terms of the beam-beam effect is highlighted. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY070  
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TUPTY077 Strong-Strong Beam-Beam Simulation of Bunch Length Splitting at the LHC simulation, emittance, synchrotron, beam-beam-effects 2210
 
  • J. Qiang, S. Paret
    LBNL, Berkeley, California, USA
  • K. Ohmi
    KEK, Ibaraki, Japan
  • T. Pieloni
    CERN, Geneva, Switzerland
  
  Longitudinal bunch length splitting was observed for some LHC beams. In this paper, we will report on the study of the observation using strong-strong beam-beam simulations. We explore a variety of factors including initial momentum deviation, collision crossing angle, synchroton tune, chromaticity, working points and bunch intensity that contribute to the beam particle loss and the bunch length splitting, and try to understand the underlying mechanism of the observed phenomena.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPTY077  
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TUPWI049 Polarized Proton Beam for eRHIC polarization, emittance, proton, booster 2360
 
  • H. Huang, F. Méot, V. Ptitsyn, T. Roser
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
RHIC has provided polarized proton collisions from 31 GeV to 255 GeV in past decade. To preserve polarization through numerous depolarizing resonances through the whole accelerator chain, harmonic orbit correction, partial snakes, horizontal tune jump system and full snakes have been used. In addition, close attentions have been paid to betatron tune control, orbit control and beam line alignment. The polarization of 60% at 255 GeV has been delivered to experiments with 1.8×1011 bunch intensity. For the eRHIC era, the beam brightness has to be maintained to reach the desired luminosity. Since we only have one hadron ring in the eRHIC era, existing spin rotator and snakes can be converted to six snake configuration for one hadron ring. With properly arranged six snakes, the polarization can be maintained at 70% at 250 GeV. This paper summarizes the effort and plan to reach high polarization with small emittance for eRHIC. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI049  
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TUPWI053 Polarization Simulations in the RHIC Run 15 Lattice optics, polarization, simulation, lattice 2372
 
  • F. Méot, H. Huang, Y. Luo, V.H. Ranjbar, G. Robert-Demolaize
    BNL, Upton, Long Island, New York, USA
  • S.M. White
    ESRF, Grenoble, France
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
RHIC polarized proton Run 15 uses a new acceleration ramp optics, compared to RHIC Run~14 and earlier runs, in relation with electron-lens beam-beam compensation developments. The new optics induces different strengths in the depolarizing snake resonance sequence, from injection to top energy. As a consequence, polarization transport along the new ramp has been investigated, based on spin tracking simulations. Sample results are reported and discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPWI053  
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WEXB3 Realization of Pseudo Single Bunch Operation with Adjustable Frequency kicker, experiment, operation, timing 2396
 
  • C. Sun, G.J. Portmann, D. Robin, C. Steier
    LBNL, Berkeley, California, USA
  
  Funding: This work is supported by the Director Office of Science of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
We present the concept and results of pseudo-single-bunch (PSB) operation–a new operational mode at the advanced light source–that can greatly expand the capabilities of synchrotron light sources to carry out dynamics and time-of-flight experiments. In PSB operation, a single electron bunch is displaced transversely from the other electron bunches using a short-pulse, high-repetition-rate kicker magnet. Experiments that require light emitted only from a single bunch can stop the light emitted from the other bunches using a collimator. Other beam lines will only see a small reduction in flux due to the displaced bunch. As a result, PSB allows to run timing experiments during the multibunch operation. Furthermore, the time spacing of PSB pulses can be adjusted from milliseconds to microseconds with a novel “kick-and-cancel” scheme, which can significantly alleviate complications of using high-power choppers and substantially reduce the rate of sample damage. 		 
slides icon Slides WEXB3 [128.794 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEXB3  
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WEYB1 Benchmarking and Application of Space Charge Codes for Rings space-charge, simulation, lattice, experiment 2402
 
  • S. Machida
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  
  This presentation should present an overview of efforts for benchmarking and application of space charge codes for rings. After briefly recalling the historical background of the simulation efforts of space charge effects in rings, we will overview the present benchmarking efforts against experimental results.  
slides icon Slides WEYB1 [6.541 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEYB1  
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WEYB3 Interplay of Beam-Beam, Lattice Nonlinearity, and Space Charge Effects in the SuperKEKB Collider lattice, luminosity, space-charge, quadrupole 2413
 
  • D. Zhou, H. Koiso, A. Morita, K. Ohmi, Y. Ohnishi, K. Oide, H. Sugimoto
    KEK, Ibaraki, Japan
  • Y. Zhang
    IHEP, Beijing, People's Republic of China
  
  The SuperKEKB B-factory adopts nanobeam scheme for the collision, which consists of large crossing angle and very small vertical beta function at the interaction point. Simulations have revealed that the luminosity of SuperKEKB will be very sensitive to perturbations from various sources. This paper discusses various beam dynamics issues involved in the SuperKEKB collider, including beam-beam, lattice nonlinearity, and space charge effects, as well as their interplay and planned mitigations.  
slides icon Slides WEYB3 [11.722 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEYB3  
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WEAB2 Beam and Spin Dynamics for Storage Ring Based EDM Search dipole, simulation, storage-ring, experiment 2454
 
  • A. Lehrach
    FZJ, Jülich, Germany
  
  Funding: On behalf of the JEDI collaboration and JARA-FAME (Jülich Aachen Research Alliance)
Permanent EDMs (electric dipole moment) of fundamental particles violate both time invariance T and parity P. Assuming the CPT theorem this implies CP violation. The Standard Model (SM) predicts non-vanishing EDMs, their magnitudes, however, are expected to be unobservably small with current techniques. Hence, the discovery of a non-zero EDM would be a signal for “new physics”. As a first step towards EDM searches of charged particles in storage rings, R&D work at the Cooler Synchrotron COSY is pursued. On a longer time scale, the design and construction of a dedicated storage ring will be carried out. Spin-tracking simulations are absolutely crucial to explore the feasibility of the planned storage ring EDM experiments and to investigate systematic limitations. For a detailed study during the storage and buildup of the EDM signal, one needs to track a large sample of particles for billions of turns. Benchmarking experiments are performed at the Cooler Synchrotron COSY to check and to further improve the simulation tools and prototype accelerator components are tested. Finally, the layout of a dedicated storage ring has to be optimized by a full simulation of spin motion. 		 
slides icon Slides WEAB2 [1.459 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEAB2  
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WEPWA014 Low Temperature Properties of 20 K Cooled Test Cavity for C-band 2.6-cell Photocathode RF Gun cavity, experiment, cryogenics, gun 2519
 
  • T. Tanaka, M. Inagaki, K. Nakao, K. Nogami, T. Sakai
    LEBRA, Funabashi, Japan
  • M.K. Fukuda, T. Takatomi, J. Urakawa, M. Yoshida
    KEK, Ibaraki, Japan
  • D. Satoh
    TIT, Tokyo, Japan
  • T.S. Shintomi
    Nihon University, Tokyo, Japan
  
  Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT).
A cryogenic C-band 2.6-cell photocathode RF gun, which operates at 20 K, is under development at Nihon University for future possibility of use in a compact linac-driven X-ray source. The cavity material is 6N8 high purity copper, the RRR of which being expected to be higher than 3000. A 2.6-cell pi-mode test cavity was fabricated for investigation of the properties under low temperature of 20 K*. Ultraprecision machining and diffusion bonding of the cavity were carried out in KEK. The operating frequency of the RF gun cavity is 5712 MHz. The machining dimensions of the test cavity were determined by taking into account the contraction of copper from room temperature to 20 K by approximately 0.33 %. The resonant frequency observed at around 21 K was 5711.761 MHz, which is 185 kHz higher than the expected value that was deduced from the resonant frequency obtained at 23.5 degree C in vacuum and the linear expansion coefficient data for OFC copper by NIST**. The unloaded Q-value of 64500 obtained at 21 K is in agreement with the SUPERFISH calculation when the surface resistance of the RRR=3000 copper was specified with taking the anomalous skin effect into account.
* T. Tanaka et al., Proceedings of IPAC2014, 658-660, http://accelconf.web.cern.ch/AccelConf
/IPAC2014/papers/mopri030.pdf
** http://cryogenics.nist.gov/MPropsMAY/OFHC%20Copper/OFHCCopperrev.htm 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA014  
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WEPWA015 RF Input Coupler for 20 K Cooled C-band 2.6-cell Photocathode RF Gun cavity, simulation, gun, network 2522
 
  • T. Tanaka, M. Inagaki, K. Nakao, K. Nogami, T. Sakai
    LEBRA, Funabashi, Japan
  • M.K. Fukuda, T. Takatomi, J. Urakawa, M. Yoshida
    KEK, Ibaraki, Japan
  • D. Satoh
    TIT, Tokyo, Japan
  • T.S. Shintomi
    Nihon University, Tokyo, Japan
  
  Funding: Work supported by the Photon and Quantum Basic Research Coordinated Development Program of the Japanese Ministry of Education, Culture, Sports, Science, and Technology (MEXT).
For future use in a compact linac-driven X-ray source, a cryo-cooled C-band photocathode RF gun is under development. The RF experiment on the basic 2.6-cell test cavity has shown that the unloaded Q-value of the cavity at 20 K can be explained by the surface resistance based on the anomalous skin effect. Since the cavity was intended for preliminary experiments of the low temperature RF properties*, a new test cavity with an RF input coupler has been designed. The basic structure of the accelerating cells has not been changed from the previous cavity. Avoiding an element with a low cooling efficiency such as the inner electrode in a coaxial coupler, a simpler cylindrical input coupler has been designed. The coupler consists of a cylindrical TM01 mode waveguide and a mode converter from a rectangular TE10 mode, with both elements placed on the accelerating axis. The structure and the dimensions of the coupler have been determined using the 3-D simulation code CST Studio so that the resonant frequency of the whole system and the coupling coefficient of the coupler meet the specifications of the RF gun. The new test cavity will be completed early in 2015 at KEK.
* T. Tanaka et al., Proceedings of IPAC2014, 658-660, http://accelconf.web.cern.ch/AccelConf
/IPAC2014/papers/mopri030.pdf 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA015  
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WEPWA041 Plans for a Linear Paul Trap at Rutherford Appleton Laboratory multipole, quadrupole, plasma, ion 2590
 
  • D.J. Kelliher, S. Machida, D.C. Plostinar, C.R. Prior, S.L. Sheehy
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  
  For over a decade, Linear Paul Traps (LPT) have been used in the study of accelerator beam dynamics. LPT studies exploit the similarity of the Hamiltonian with that of a beam in a quadrupole channel while having advantages in the flexibility of parameter choice, compactness and low cost. In collaboration with Hiroshima University, LPT research planned at STFC Rutherford Appleton Laboratory in the UK aims to investigate a range of topics including resonance crossing, halo formation, long-term stability studies and space-charge effects. Initially, a conventional quadrupole-based LPT will be built at RAL and used for a variety of experiments. In parallel, a design for a more advanced LPT that incorporates higher order multipoles will be pursued and later constructed. This multipole trap will allow non-linear lattice elements to be simulated and so broaden considerably the range of experiments that can be conducted. These will include the investigation of resonance crossing in non-linear lattices, a more detailed study of halo formation and the effect of detuning with amplitude. In this paper we report on progress made in the project to date and future plans.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA041  
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WEPWA043 Progress on the Design of the Racetrack FFAG Decay Ring for nuSTORM lattice, factory, detector, closed-orbit 2594
 
  • J.-B. Lagrange, J. Pasternak
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  • R.B. Appleby, J.M. Garland, H.L. Owen, S.C. Tygier
    UMAN, Manchester, United Kingdom
  • R.B. Appleby
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • Y. Mori
    Kyoto University, Research Reactor Institute, Osaka, Japan
  
  The neutrino beam produced from muons decaying in a storage ring would be an ideal tool for precise neutrino cross section measurements and search for sterile neutrinos due to its precisely known flavour content and spectrum. In the proposed nuSTORM facility pions would be directly injected into a storage ring, where circulating muon beam would be captured. The racetrack FFAG (Fixed Field Alternating Gradient) option for nuSTORM decay ring offers a very good performance due to a large dynamic and momentum acceptance. Machine parameters, linear optics design, beam dynamics and injection system for nuSTORM FFAG ring are discussed in this paper.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWA043  
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WEPJE015 Muon Tracking Studies in a Skew Parametric Resonance Ionization Cooling Channel coupling, quadrupole, betatron, focusing 2705
 
  • A.V. Sy, Y.S. Derbenev, V.S. Morozov
    JLab, Newport News, Virginia, USA
  • A. Afanasev
    GWU, Washington, USA
  • R.P. Johnson
    Muons, Inc, Illinois, USA
  
  Funding: This work was supported in part by U.S. DOE STTR Grant DE-SC0005589. This manuscript has been authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Skew Parametric-resonance Ionization Cooling (SPIC) is an extension of the Parametric-resonance Ionization Cooling (PIC) framework that has previously been explored as the final 6D cooling stage of a high-luminosity muon collider. The addition of skew quadrupoles to the PIC magnetic focusing channel induces coupled dynamic behavior of the beam that is radially periodic. The periodicity of the radial motion allows for the avoidance of unwanted resonances in the horizontal and vertical transverse planes, while still providing periodic locations at which ionization cooling components can be implemented. A first practical implementation of the magnetic field components required in the SPIC channel is modeled in MADX. Dynamic features of the coupled correlated optics with and without induced parametric resonance are presented and discussed. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPJE015  
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WEPMA035 Low- and High-Beta SRF Elliptical Cavity Stiffening cavity, simulation, proton, SRF 2835
 
  • E.N. Zaplatin
    FZJ, Jülich, Germany
  • A. Kanareykin
    Euclid TechLabs, LLC, Solon, Ohio, USA
  • V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  Elliptical SRF cavities are the main accelerating structures in many accelerators worldwide. Different types of external loads on the resonator walls predetermine the main working conditions of the SC cavities. The most important of them are very high electromagnetic fields that result in strong Lorentz forces and the pressure on cavity walls from the helium tank that also deforms the cavity shape. Also mechanical eigen resonances of cavities are the main source of the microphonics. To withstand any kind of external loads on the resonator walls different schemes of the cavity stiffening were applied. In the paper we report the basic investigations of the cavity stiffening using FNAL 650 MHz β=0.92 and 0.61 as an example. The single-cell investigation results were used as the reference to develop the ultimate scheme of the helium vessel structure to ensure the best resonator stability.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMA035  
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WEPMN033 The Fabrication of Prototype Normal Conducting Rebuncher for the MEBT in RISP cavity, linac, controls, operation 3000
 
  • H.J. Kim, M.O. Hyun, B.-S. Park
    IBS, Daejeon, Republic of Korea
  
  The Medium Energy Beam Transport (MEBT) system of RAON consists of several quadrupole magnets for controlling the transverse beam parameter at the entrance of the low energy linac, three normal-conducting (NC) re-bunchers to match the longitudinal beam ellipse into the acceptance of the low energy linac and several diagnostic devices. The NC QWR re-buncher, which has a frequency of 81.25 MHz, a geometric beta factor of 0.032, and an effective length of 24 cm, has been fabricated and tested to demonstrate the frequency tuning by using slug tuner, power transmission and reflection with low input power, and pulsed high power transmission with cooling channels. In this presentation, we show the design and fabrication criteria for the high power, ~ 10 kW, re-buncher and its test results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPMN033  
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WEPHA023 Ferrite-tuner Development for 80 MHz Single-Cell RF-Cavity Using Orthogonally Biased Garnets cavity, coupling, simulation, operation 3159
 
  • C. Vollinger, F. Caspers
    CERN, Geneva, Switzerland
  
  In the frame of the LHC Injector Upgrade program involving the existing 80 MHz cavities in the CERN PS accelerator, an orthogonally biased ferrite tuner is foreseen to complement the current motor-driven piston tuner. This ferrite tuner shall provide the possibility of a fast frequency shift of about 200 kHz on the fundamental mode, to allow a fast switching between proton and ion frequencies. In order to avoid water cooling and related issues, the challenge was to bring magnetic losses in the tuner to a minimum such that a forced air cooling scheme will be sufficient. The tuner was first designed with simulation tools, a prototype was built and low-power RF testing was performed on the tuner-cavity combination to evaluate tuning range, bandwidth, and stability. These tests were carried out on a single-cell copper RF cavity mock-up with a resonance frequency of 88 MHz, where the ferrite tuner is connected via a tuning loop and the perpendicular magnetic bias for ferrite tuner is provided by a DC bias supply. Simulations and test data will be presented.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA023  
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WEPHA024 Preliminary Design of a Perpendicular Biased Ferrite Loaded Accelerating Cavity cavity, simulation, operation, factory 3163
 
  • J. Eberhardt, F. Caspers, C. Vollinger
    CERN, Geneva, Switzerland
  
  A ferrite loaded accelerating cavity with a frequency sweep of 18 to 40 MHz is studied for a possible upgrade of the CERN accelerator complex. The resonance frequency of a ferrite loaded cavity shifts by applying an external magnetic bias field to the ferrite material by means of changing the relative permeability. We present the electromagnetic design of such a cavity with a special emphasis on the modeling of the nonlinear, anisotropic and dispersive characteristics of the ferrite’s relative permeability above magnetic saturation. For experimental crosscheck, a ferrite loaded resonant test setup was built which provides results for the material performance in a magnetic bias field. A comparison of numerical simulations and experimental measurements is shown and calculations are benchmarked by measurement data. Based on this study a preliminary design of a ferrite loaded accelerating cavity is described.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA024  
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WEPHA053 Surface Resistance RF Measurements of Materials Used for Accelerator Vacuum Chambers cavity, coupling, factory, network 3235
 
  • P. Goudket, L. Gurran, O.B. Malyshev, M.D. Roper, R. Valizadeh, S. Wilde
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • G. Burt, L. Gurran
    Cockcroft Institute, Lancaster University, Lancaster, United Kingdom
  • P. Goudket, O.B. Malyshev, R. Valizadeh
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • S. Wilde
    Loughborough University, Loughborough, Leicestershire, United Kingdom
  
  The RF surface resistance of accelerator vacuum chamber walls can have a significant impact on the beam quality. There is a need to know how the use of a new material, surface coating or surface treatment can affect the RF surface resistance. ASTeC and Lancaster University have designed and built two test cavities where one face can be replaced with a sample in the form of a flat plate. The measurements are performed with a network analyser at the resonant frequency of approximately 7.8 GHz.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPHA053  
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WEPTY017 Development of 650 MHz β=0.9 5-cell Elliptical Cavities for PIP-II cavity, proton, linac, controls 3296
 
  • M.H. Awida, M.H. Foley, I.V. Gonin, C.J. Grimm, T.N. Khabiboulline, A. Lunin, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  
  5-cell 650 MHz elliptical cavities are being developed for the Proton Improvement Plan II (PIP-II) of Fermilab. The cavities are designed to accelerate protons of relative group velocity β=0.9 at the high energy part of the linear particle accelerator. In this paper, we report the status of these cavities and summarize the results of the quality control measurements performed on four initial prototypes.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY017  
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WEPTY018 Analysis of a Quasi-waveguide Multicell Resonator for SPX cavity, wakefield, higher-order-mode, niobium 3299
 
  • M.H. Awida, I.V. Gonin, T.N. Khabiboulline, A. Lunin, V.P. Yakovlev
    Fermilab, Batavia, Illinois, USA
  • A. Zholents
    ANL, Argonne, Ilinois, USA
  
  A compact deflecting cavity is needed for the Short Pulse X-rays (SPX) at the Advanced Photon Source (APS) of Argonne national laboratory. The deflecting cavity has to quite efficient providing a 2 MV kick voltage and satisfying stringent requirements on aperture size and total cavity length. Meanwhile, the cavity should allow operation up to 100 mT peak surface magnetic field before quenching. In this paper, we report on the latest analysis carried out on the cavity structure to investigate frequency sensitivity to pressure fluctuations, frequency sensitivity to tuning forces, modal frequency, and wakefield losses.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY018  
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WEPTY036 Progress at FNAL in the Field of the Active Resonance Control for Narrow Bandwidth SRF Cavities. cavity, feedback, operation, controls 3355
 
  • W. Schappert, J.P. Holzbauer, Y.M. Pischalnikov
    Fermilab, Batavia, Illinois, USA
  
  Funding: Fermi Research Alliance, LLC under Contract N. DE-AC02-07CH11359 with U.S. Department of Energy.
Recent efforts at FNAL to actively compensate microphonics in narrow bandwidth cavities are discussed. Feed-forward compensation of Lorentz force detuning in combination with feedback of the forward/probe phase difference to a piezo actuator successfully stabilized the resonance of a 325 MHz spoke resonator to within 11 mHz of the frequency of the open-loop CW RF drive over a two hour interval. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPTY036  
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WEPWI007 TTF3 Power Coupler Thermal Analysis for LCLS-II CW Operation simulation, operation, cavity, SRF 3503
 
  • L. Xiao, C. Adolphsen, Z. Li, C.D. Nantista, T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
  • I.V. Gonin, N. Solyak
    Fermilab, Batavia, Illinois, USA
  
  The TESLA 9-cell SRF cavity design has been adopted for use in the LCLS-II SRF Linac. Its TTF3 coaxial Fundamental Power Coupler (FPC), developed for pulsed operation in the European XFEL and ILC, requires modest changes to make it suitable for LCLS-II CW operation, in which it must be able to handle up to 7 kW of average power with the maximum temperature rise not to exceed 150 C. In order to improve TTF3 FPC cooling, an increased copper plating thickness will be used on the inner and outer conductor stainless steel RF surfaces. Fully 3D FPC thermal analysis with copper plating was performed using the SLAC developed parallel finite element code suite ACE3P with integrated electromagnetic, thermal and mechanical multi-physics simulation capabilities. In this paper, we present TTF3 FPC thermal analysis simulation results obtained using ACE3P as well as a comparison with measurement results.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI007  
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WEPWI010 Results from the First Single Cell Nb3Sn Cavity Coatings at JLab cavity, niobium, network, accelerating-gradient 3509
 
  • G.V. Eremeev
    JLab, Newport News, Virginia, USA
  
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Nb3Sn is a promising superconducting material for SRF applications and has the potential to exceed the limitations of niobium. We have used the recently commissioned Nb3Sn coating system to investigate Nb3Sn coatings on several single cell cavities by applying the same coating procedure on several different single cells with different history and pre-coating surface preparation. We report on our findings with four 1.5 GHz CEBAF-shape single cell and one 1.3 GHz ILC-shape single cavities that were coated, inspected, and tested. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI010  
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WEPWI061 Design of Normal Conducting 704 MHz and 2.1 GHz Cavities for LEReC Linac cavity, impedance, electron, simulation 3634
 
  • B. P. Xiao, S.A. Belomestnykh, I. Ben-Zvi, J.C. Brutus, A.V. Fedotov, G.T. McIntyre, K.S. Smith, J.E. Tuozzolo, Q. Wu, W. Xu, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
  • S.A. Belomestnykh, I. Ben-Zvi
    Stony Brook University, Stony Brook, USA
  • V. Veshcherevich
    Cornell University (CLASSE), Cornell Laboratory for Accelerator-Based Sciences and Education, Ithaca, New York, USA
  
  Funding: Work is supported by Brookhaven Science Associates, LLC under contract No. DE-AC02-98CH10886 with the US DOE.
To improve RHIC luminosity for heavy ion beam energies below 10 GeV/nucleon, the Low Energey RHIC electron Cooler (LEReC) is currently under development at BNL. Two normal conducting cavities, a single cell 704 MHz cavity and a 3 cell 2.1 GHz third harmonic cavity, will be used in LEReC for bunch stretching and energy spread correction. In this paper we report the design of these two cavities. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-WEPWI061  
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THPF002 Space Charge Effect Estimation for Synchrotrons with Third-order Resonant Extraction space-charge, extraction, proton, injection 3677
 
  • M.T.F. Pivi, A. Garonna
    EBG MedAustron, Wr. Neustadt, Austria
  
  In proton and ion storage rings using the third-order resonance extraction mechanism, beam particles are slowly extracted from the ring when reaching the resonance stop-band. Typically at beam injection, the horizontal tune is set to a value close to the resonance value. The tune is then moved towards the resonance value to trigger beam extraction in a controlled way. The tune shift generated by space charge forces needs to be taken into account. For this, the incoherent space-charge tune shift for protons of the MedAustron accelerator main ring has been evaluated. This has been performed by multi-particle tracking using an optics model based on MADX, considering a realistic Gaussian beam distribution and exact non-linear space charge electric field forces. The MedAustron accelerator is in the beam commissioning phase and is planned to start medical commissioning at the end of 2015.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF002  
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THPF019 Status and First Measurement Results for a High Gradient CH-Cavity cavity, linac, ion, operation 3724
 
  • A. Almomani, U. Ratzinger
    IAP, Frankfurt am Main, Germany
  
  Funding: BMBF, contract no. 05P12RFRB9
This pulsed linac activity aims on compact designs and on a considerable increase of the voltage gain per meter. A high gradient CH-cavity operated at 325 MHz was developed at IAP-Frankfurt. The mean effective accelerating field for this cavity is expected well above 10 MV/m at β = 0.164. This cavity is developed within a funded project. The results might influence the rebuilt of the UNILAC-Alvarez section, aiming to achieve the beam intensities specified for the GSI - FAIR project (15 mA U28+). Another motivation is the development of an efficient pulsed ion accelerator for significantly higher energies like 60 AMeV. The new GSI 3 MW Thales klystron test stand will be used for the cavity RF power tests. Detailed studies on two different types of copper plating will be performed with this cavity. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF019  
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THPF021 Structural, Mechanical and RF Measurements on the Superconducting 217 MHz CH Cavity for the CW Demonstrator at GSI cavity, simulation, niobium, operation 3730
 
  • F.D. Dziuba, M. Amberg, M. Basten, M. Busch, H. Podlech
    IAP, Frankfurt am Main, Germany
  • M. Amberg, K. Aulenbacher, W.A. Barth, S. Mickat
    HIM, Mainz, Germany
  • K. Aulenbacher
    IKP, Mainz, Germany
  • W.A. Barth, S. Mickat
    GSI, Darmstadt, Germany
  
  Funding: Work supported by HIM, GSI, BMBF Contr. No. 05P12RFRBL
Together with the new horizontal cryomodule and two superconducting (sc) 9.5 T solenoids the sc 217 MHz Crossbar-H-mode (CH) cavity represents the continuous wave (cw) demonstrator and brings sc rf technology to GSI. A reliable operability of the sc CH cavity is one major goal of the demonstrator project. Furthermore, the successful beam operation of the demonstrator will be a milestone on the way to a new sc cw linac at GSI for a competitive production of Super Heavy Elements (SHE) in the future. The production of the cryomodule and the solenoids is almost finished while the cavity has been completed except for the helium vessel. In this paper structural mechanical as well as related rf measurements on the sc 217 MHz CH cavity are presented. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF021  
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THPF031 Towards an RF Wien-Filter for EDM Experiments at COSY dipole, polarization, betatron, storage-ring 3761
 
  • S. Mey, R. Gebel
    FZJ, Jülich, Germany
  
  Funding: The work is supported within the framework of the Helmholtz Association’s Accelerator Research and Development (ARD) program.
The JEDI Collaboration (Jülich Electric Dipole Moment (EDM) Investigations) is developing tools for the measurement of permanent EDMs of charged, light hadrons in storage rings. The Standard Model predicts unobservably small values for the EDM, but a non-vanishing EDM can be detected by measuring a tiny build-up of vertical polarization in a beforehand horizontally polarized beam. This technique requires a spin tune modulation by an RF Dipole without any excitation of beam oscillations. In the course of 2014, a prototype RF ExB-Dipole has been successfully commissioned and tested. To determine the characteristics of the device, the force of a radial magnetic field is canceled out by a vertical electric one. In this configuration, the dipole fields form a Wien-Filter that directly rotates the particles' polarization vector. We verified that the device can be used to continuously flip the vertical polarization of a 970 MeV(c deuteron beam without exciting any coherent beam oscillations. For a first EDM Experiment, the RF ExB-Dipole in Wien-Filter Mode is going to be rotated by 90° around the beam axis and will be used for systematic investigations of sources for false EDM signals. 		 
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF031  
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THPF032 Spin Tracking Simulations Towards Electric Dipole Moment Measurements at COSY quadrupole, solenoid, polarization, distributed 3764
 
  • M. Rosenthal, A. Lehrach
    FZJ, Jülich, Germany
  • A. Lehrach, M. Rosenthal
    RWTH, Aachen, Germany
  
  A strong hint for physics beyond the Standard Model would be achieved by direct measurements of charged particles' Electric Dipole Moments (EDMs). Measurements in magnetic storage rings using a resonant spin interaction of a radiofrequency Wien filter are proposed and needs to be scrutinized. Therefore, the calculation of phase space transfer maps for time-varying fields has been implemented into an extensions for the software framework COSY INFINITY. Benchmarking with measured data and analytical estimates for rf solenoid induced spin resonances are in good agreement. The dependence of polarization oscillation damping on the solenoid frequency could be confirmed. First studies of the rf Wien filter method reveal systematic limitations: Uncorrected Gaussian distributed misalignments of the COSY lattice quadrupoles with a standard deviation of 0.1 mm generate a similar buildup as an EDM of 5·10-19 e cm using this method.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF032  
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THPF062 CADS 650 MHz β=0.63 Elliptical Cavity Study cavity, HOM, linac, proton 3836
 
  • L.J. Wen, Y. He, Y.M. Li, S.H. Zhang
    IMP/CAS, Lanzhou, People's Republic of China
  
  The China Accelerator Driven Sub-critical System (CADS) is a high intensity proton facility to dispose of nuclear waste and generate electric power. CADS is based on 1.5 GeV, 10mA CW superconducting (SC) linac as a driver. The high-energy section of the linac is composed of two families of SC elliptical cavities which are designed for the geometrical beta 0.63 and 0.82. In this paper, the 650 MHz β=0.63 SC elliptical cavity was studied, including cavity optimization, multipacting, high order modes (HOM) and generator RF power calculation.  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-THPF062  
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