Keyword: emittance
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MOOBS1 Beam Dynamics Issues in the SNS Linac linac, laser, ion, optics 12
 
  • A.P. Shishlo
    ORNL, Oak Ridge, Tennessee, USA
 
  Funding: This research is supported by UT-Battelle, LLC for the U. S. Department of Energy under contract No. DE-AC05-00OR22725
A review of the Spallation Neutron Source (SNS) linac beam dynamics is presented. It describes transverse and longitudinal beam optics, losses, activation, and comparison between the initial design and the existing accelerator. The SNS linac consists of normal conducting and superconducting parts. The peculiarities in operations with the superconducting part of the SNS linac (SCL), estimations of total losses in SCL, the possible mechanisms of these losses, and the progress in the transverse matching are discussed.
 
slides icon Slides MOOBS1 [1.270 MB]  
 
MOOCS4 Time-Dependent Phase-Space Measurements of the Longitudinally Compressing Beam in NDCX-I target, plasma, ion, electron 61
 
  • S.M. Lidia, G. Bazouin, P.A. Seidl
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
The Neutralized Drift Compression Experiment (NDCX-I) generates high intensity ion beams to explore Warm Dense Matter physics. A ~150 kV, ~500 ns ramped voltage pulse is applied to a ~300 keV, 5-10 μs, 25 mA K+ ion beam across a single induction gap. The velocity modulated beam compresses longitudinally during ballistic transport along a space-charge-neutralizing plasma transport line, resulting in ~3A peak current with ~2-3 ns pulse durations (FWHM) at the target plane. Transverse final focusing is accomplished with a ~8 T, 10 cm long pulsed solenoid magnet. Time-dependent focusing in the induction gap, and chromatic aberrations in the final focus optics limit the peak fluence at the target plane for the compressed beam pulse. We report on time-dependent phase space measurements of the compressed pulse in the ballistic transport beamline, and measurement of the time-dependent radial impulses derived from the interaction of the beam and the induction gap voltage. We present results of start-to-end simulations to benchmark the experiments. Fast correction strategies are discussed with application to both NDCX-I and to the new NDCX-II accelerator.
 
slides icon Slides MOOCS4 [7.432 MB]  
 
MOOCS5 Space-charge Effects in H Low-energy Beam Transport of LANSCE space-charge, beam-transport, simulation, vacuum 64
 
  • Y.K. Batygin, C. Pillai, L. Rybarcyk
    LANL, Los Alamos, New Mexico, USA
 
  The 750-keV low-energy beam transport of the Los Alamos Neutron Science Center (LANSCE) linac consists of two independent beam lines for simultaneous injection of H+ and H beams into the linear accelerator. While transport of the H+ beam is seriously affected by uncompensated space charge forces, the same effect for H is hidden by presence of multiple beam collimators and beam chopping. Recent results from beam development experiments indicate a significant influence of space charge on H beam dynamics in the low-energy beam transport. Measurements of beam emittance along beam transport show the formation of S-shaped filamentation in the particle distribution phase space, typical with the presence of non-linear space charge forces. Results are supported by particle tracking simulations with the PARMILA, BEAMPATH, and TRACE codes.  
slides icon Slides MOOCS5 [6.304 MB]  
 
MOODN1 Results of Head-on Beam-beam Compensation Studies at the Tevatron antiproton, electron, proton, simulation 67
 
  • A. Valishev, G. Stancari
    Fermilab, Batavia, USA
 
  Funding: Work supported by the Fermi Research Alliance, LLC under Contract DE-AC02-07CH11359 with the United States Department of Energy, and by the DOE through the US LHC Accelerator Research Program (LARP).
At the Tevatron collider, we studied the feasibility of suppressing the antiproton head-on beam-beam tune spread using a magnetically confined 5-keV electron beam with Gaussian transverse profile overlapping with the circulating beam. When electron cooling of antiprotons is applied in regular Tevatron operations, the head-on beam-beam effect on antiprotons is small. Therefore, we first focused on the operational aspects, such as beam alignment and stability, and on fundamental observations of tune shifts, tune spreads, lifetimes, and emittances. We also attempted two special collider stores with only 3 proton bunches colliding with 3 antiproton bunches, to suppress long-range forces and enhance head-on effects. We present here the results of this study and a comparison between numerical simulations and observations, in view of the planned application of this compensation concept to RHIC.
 
slides icon Slides MOODN1 [2.680 MB]  
 
MOODS1 Space-Charge Effects in Bunched and Debunched Beams focusing, space-charge, electron, linac 85
 
  • B.L. Beaudoin, S. Bernal, K. Fiuza, I. Haber, R.A. Kishek, T.W. Koeth, P.G. O'Shea, M. Reiser, D.F. Sutter
    UMD, College Park, Maryland, USA
 
  Funding: This work is funded by the US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office
The University of Maryland Electron Ring (UMER) is a machine designed to study high-intensity beam physics. With the application of axial fields to the bunch ends, we are able to keep a beam with an injected tune shift of 1.0, bunched over multiple turns. This is feasible with the application of tailored fields to optimally match the space-charge self-fields while minimizing the excitation of longitudinal space-charge waves. With this scheme, we have been able to extend the number of turns at the University of Maryland Electron Ring (UMER) by a factor of ten. Without the use of longitudinal focusing, head and tail effects begin to dominate, especially with the higher current beams. Time resolved measurements of the peak correlated energy spread have shown in some cases a change in the overall spread of 1.8% for the 0.6 mA beam, from the injected beam energy.
 
slides icon Slides MOODS1 [2.834 MB]  
 
MOODS3 Studies of RF Noise Induced Bunch Lengthening at the LHC background, proton, ion, cavity 91
 
  • T. Mastoridis, J.D. Fox, C.H. Rivetta
    SLAC, Menlo Park, California, USA
  • P. Baudrenghien, A.C. Butterworth, J.C. Molendijk
    CERN, Geneva, Switzerland
 
  Funding: Work supported by the U.S. Department of Energy under contract # DE-AC02-76SF00515 and the US LHC Accelerator Research Program (LARP).
Radio Frequency noise induced bunch lengthening can strongly affect the Large Hadron Collider performance through luminosity reduction, particle loss, and other effects. Models and theoretical formalisms demonstrating the dependence of the LHC longitudinal bunch length on the RF station noise spectral content have been presented*,**. Initial measurements validated these studies and determined the performance limiting RF components. For the existing LHC LLRF implementation the bunch length increases with a rate of 1 mm/hr, which is higher than the intrabeam scattering diffusion and leads to a 27% bunch length increase over a 20 hour store. This work presents measurements from the LHC that better quantify the relationship between the RF noise and longitudinal emittance blowup. Noise was injected at specific frequency bands and with varying amplitudes at the LHC accelerating cavities. The experiments presented in this paper confirmed the predicted effects on the LHC bunch length due to both the noise around the synchrotron frequency resonance and the noise in other frequency bands aliased down to the synchrotron frequency by the periodic beam sampling of the accelerating voltage.
*T. Mastorides et.al., "RF system models for the LHC with Application to Longitudinal Dynamics,"
**T. Mastorides et.al., "RF Noise Effects on Large Hadron Collider Beam Diffusion"
 
slides icon Slides MOODS3 [0.644 MB]  
 
MOODS6 Beam Dynamics Simulations on the ESS Bilbao RFQ rfq, simulation, cavity, acceleration 100
 
  • D. de Cos, I. Bustinduy, O. Gonzalez, J.L. Munoz, A. Velez
    ESS Bilbao, Bilbao, Spain
  • F.J. Bermejo
    Bilbao, Faculty of Science and Technology, Bilbao, Spain
  • V. Etxebarria, J. Portilla
    University of the Basque Country, Faculty of Science and Technology, Bilbao, Spain
  • J. Feuchtwanger
    ESS-Bilbao, Zamudio, Spain
  • S. Jolly, P. Savage
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  • A.P. Letchford
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  Funding: European Spallation Source - Bilbao
The Bilbao Accelerator RFQ is aimed to accelerate a 75 mA proton beam from 75 keV to 3 MeV, while keeping the beam both transversely and longitudinally focused, and presenting a minimum emittance growth. We report on the current status of the project, mainly focusing on the Beam Dynamics aspects of the design. Several particle simulations are carried out with RFQSIM, GPT and TRACK codes, in order to study the particle transmission of the RFQ under several circumstances, such as different current levels, vane geometry changes due to thermal stress, and different input beam characteristics obtained by changing the LEBT operation settings.
 
slides icon Slides MOODS6 [3.264 MB]  
 
MOP001 Charge Separation for Muon Collider Cooling solenoid, collider, simulation, acceleration 103
 
  • R. B. Palmer, R.C. Fernow
    BNL, Upton, Long Island, New York, USA
 
  Most schemes for six dimensional muon ionization cooling work for only one sign. It is then necessary to have charge separation prior to that cooling. Schemes of charge separation using bent solenoids are described, and their simulated performances reported. It is found that for efficient separation, it should take place at somewhat higher momenta than commonly used for the cooling.  
 
MOP002 Tapered Six-Dimensional Cooling Channel for a Muon Collider collider, solenoid, simulation, lattice 106
 
  • R. B. Palmer, R.C. Fernow
    BNL, Upton, Long Island, New York, USA
 
  A high-luminosity muon collider requires a reduction of the six-dimensional emittance of the captured muon beam by a factor of approximately 106. Most of this cooling takes place in a dispersive channel that simultaneously reduces all six phase space dimensions. We describe a tapered 6D cooling channel that should meet the requirements of a muon collider. The parameters of the channel are given and preliminary simulations are shown of the expected performance.  
 
MOP003 Six-Dimensional Bunch Merging for Muon Collider Cooling wiggler, kicker, simulation, collider 109
 
  • R. B. Palmer, R.C. Fernow
    BNL, Upton, Long Island, New York, USA
 
  A muon collider requires single, intense, muon bunches with small emittances in all six dimensions. It is most efficient to initally phase-rotate the muons into many separate bunches, cool these bunches in six dimensions (6D), and, when cool enough, merge them into single bunches (one of each sign). Previous studies only merged in longitudinal phase space (2D). In this paper we describe merging in all six dimensions (6D). The scheme uses rf for longitudinal merging, and kickers and transports with differing lengths (trombones) for transverse merging. Preliminary simulations, including incorporation in 6D cooling, is described.  
 
MOP015 An X-band Gun Test Area at SLAC gun, optics, quadrupole, cavity 133
 
  • C. Limborg-Deprey, C. Adolphsen, T.S. Chu, M.P. Dunning, C. Hast, R.K. Jobe, E.N. Jongewaard, A.E. Vlieks, D.R. Walz, F. Wang
    SLAC, Menlo Park, California, USA
  • S.G. Anderson, F.V. Hartemann, T.L. Houck, R.A. Marsh
    LLNL, Livermore, California, USA
 
  Funding: Work supported by the U.S. DOE Contract No. DE-AC03-76SF00515
The XTA (X-Band Test Area) is being assembled in the NLCTA tunnel of the SLAC National Laboratory to serve as a test facility for new RF guns. The first gun to be tested will be an upgraded version of the 5.6 cell, 200MV/m peak field X-band designed at SLAC in 2003 for the Compton Scattering experiment run in ASTA. This new version includes some features implemented in 2006 on the LCLS gun such as racetrack couplers, increased mode separation and elliptical irises. These upgrades were discussed in collaboration with LLNL since the same gun will be used as a driver for the LLNL Gamma-ray Source. Our beamline includes an X-band accelerating section which takes the electron beam up to 100 MeV and an electron beam measurement station. Other X-Band guns such as the UCLA Hybrid gun will be characterized at our facility.
 
 
MOP016 Preliminary Simulations of Plasma Wakefield Accelerator Experiments at FACET plasma, electron, simulation, wakefield 136
 
  • W. An, C. Joshi, W. Lu, W.B. Mori
    UCLA, Los Angeles, California, USA
  • M.J. Hogan
    SLAC, Menlo Park, California, USA
  • C. Huang
    LANL, Los Alamos, New Mexico, USA
 
  Funding: This work is supported by USDoE under DE-FC02-07ER41500, DE-FG02-92ER40727 and NSF under NSF PHY-0904039, PHY-0936266.
Recent experiments on former facility FFTB at SLAC has demonstrated that a single electron beam driven Plasma Wakefield Accelerator (PWFA) can be produced with an accelerating gradient of 52 GeV/m over a meter-long scale*. If another electron bunch is properly loaded into such a wakefield, it will obtain a high energy gain in a short distance as well as a small energy spread. Such PWFA experiment with two bunches will be performed in FACET, which is a new facility at SLAC**. Simulation results show that with possible beam parameters in FACET the first electron bunch (with less current than that in the FFTB experiment) can still produce a meter-long plasma column with a density of 5x1016 cm-3 via field ionization when we use a gas with a lower ionization energy. The second electron bunch can have a 10 GeV energy gain with a very narrow energy spread. If a pre-ionized plasma is used instead of the neutral gas, the energy gain of the second bunch can be enhanced to 30 GeV.
* I. Blumenfeld et al., Nature 445, 741 (2007).
** M. J.Hogan, et al.,NewJ. Phys.12, 055030(2010).
 
 
MOP019 Performance of the Bucked Coils Muon Cooling Lattice for the Neutrino Factory lattice, factory, simulation, cavity 145
 
  • A. Alekou
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  • J. Pasternak
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  • C.T. Rogers
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
 
  Ionization cooling is essential to the Neutrino Factory in order to decrease the large emittance of the tertiary muon beam. Strong focusing and a large RF gradient in the cooling channel are required for efficient cooling; however, the presence of a strong magnetic field inside the RF cavities limits their performance by lowering the breakdown limit. In order to mitigate this problem a new lattice configuration, the Bucked Coils, is proposed: two solenoidal coils of different radius and opposite polarities are placed along the channel at the same z-positions. The Bucked Coils lower the magnetic field in the RF cavities while also providing strong focusing. This paper presents the results of the beam dynamics simulations in the new lattice, using the G4MICE code. The comparison of the achieved cooling performance and transmission between the currently proposed Neutrino Factory baseline lattice (FSIIA) and the new configuration is provided in detail.  
 
MOP021 The MICE Muon Beamline and Induced Host Accelerator Beam Loss target, factory, synchrotron, injection 148
 
  • A.J. Dobbs, A. Alekou, K.R. Long
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
 
  Funding: Science and Technology Facilities Council
The international Muon Ionisation Cooling Experiment (MICE) is designed to provide a proof of principle of ionisation cooling to reduce the muon beam phase space at a future Neutrino Factory and Muon Collider. The MICE Muon Beam is generated by the decay of pions produced by dipping a cylindrical titanium target into the proton beam of the 800 MeV ISIS synchrotron at the Rutherford Appleton Laboratory, U.K. Studies of the particle rate in the MICE Muon Beamline and its relationship to induced beam loss in ISIS are presented, using data taken in Summer 2010. Using time-of-flight to perform particle identification estimates of muon rates are presented and related to induced beam loss.
 
 
MOP022 The Expected Performance of MICE Step IV optics, scattering, solenoid, lattice 151
 
  • T. Carlisle, J.H. Cobb
    JAI, Oxford, United Kingdom
 
  Funding: STFC
The international Muon Ionization Cooling Experiment (MICE), under construction at the Rutherford Appleton Laboratory in Oxfordshire (UK), is a test of a prototype cooling channel for a future Neutrino Factory. The experiment aims to achieve, using liquid hydrogen absorbers, a 10% reduction in transverse emittance, measured to an accuracy of 1% by two scintillating fibre trackers within 4 T solenoid fields. Step IV of MICE will begin in 2012, producing the experiment's first cooling measurements. Step IV uses an absorber focus coil module, placed between the two trackers, to house liquid hydrogen or solid absorbers. The performance of Step IV using various absorber materials was simulated. Multiple scattering in high Z absorbers was found to mismatch the beam with the lattice optics, which was largely corrected by re-tuning the MICE lattice accordingly.
 
 
MOP023 Particle Tracking and Beam Matching Through the New Variable Thickness MICE Diffuser solenoid, factory, collider, target 154
 
  • V. Blackmore, J.H. Cobb, M. Dawson, J. Tacon, M. Tacon
    Oxford University, Physics Department, Oxford, Oxon, United Kingdom
 
  The Muon Ionisation Cooling Experiment (MICE) aims to demonstrate the transverse cooling of muons for a possible future Neutrino Factory or Muon Collider. The diffuser is an integral part of the MICE cooling channel. It aims to inflate the emittance of the incoming beam such that cooling can later be measured in the MICE channel. A novel new diffuser design is currently in development at Oxford, consisting of a high density scatterer of variable radiation lengths. Simulations have been carried out in order to fully understand the physics processes involved with the new diffuser design and to enable a proper matching of the beam to the MICE channel.  
 
MOP037 Muon Ionization Cooling Experiment: Controls and Monitoring controls, monitoring, EPICS, target 166
 
  • P.M. Hanlet
    IIT, Chicago, Illinois, USA
 
  Funding: NSF
The Muon Ionization Cooling Experiment (MICE) is a demonstration experiment to prove the viability of cooling a beam of muons for use in a Neutrino Factory and Muon Collider. The MICE cooling channel is a section of a modified Study II cooling channel which will provide a 10% reduction in beam emittance. In order to ensure a reliable measurement, we intend to measure the beam emittance before and after the cooling channel at the level of 1%, or an absolute measurement of 0.001. This renders MICE as a precision experiment which requires strict controls and monitoring of all experimental parameters in order to control systematic errors. The MICE Controls and Monitoring system is based on EPICS and integrates with the DAQ, detector, environment, and data monitoring systems. A description of this system, its implementation, and performance during recent muon beam data collection will be discussed.
 
 
MOP040 Fast Time-of-Flight System for Muon Cooling Experiments simulation, cathode, scattering, collider 172
 
  • R.J. Abrams, C.M. Ankenbrandt, G. Flanagan, S.A. Kahn, M. Notani, T.J. Roberts
    Muons, Inc, Batavia, USA
  • H.J. Frisch
    Enrico Fermi Institute, University of Chicago, Chicago, Illinois, USA
 
  Funding: Supported in part by SBIR Grant DE-SC0005445.
A new generation of large-area, low cost time-of-flight detectors with time resolutions ≤ 10 ps and space resolutions ≤ 1 mm is being developed for use in nuclear and particle physics experiments, as well as for medical and industrial applications. Such detectors are being considered for use in muon cooling channel tests. Designs and fabrication of prototype planes and associated readout electronics are described. Results of simulations of time and space resolutions are presented.
 
 
MOP050 EPIC Muon Cooling Simulations using COSY INFINITY ion, resonance, dipole, quadrupole 190
 
  • J.A. Maloney, B. Erdelyi
    Northern Illinois University, DeKalb, Illinois, USA
  • A. Afanasev, R.P. Johnson
    Muons, Inc, Batavia, USA
  • S.A. Bogacz, Y.S. Derbenev
    JLAB, Newport News, Virginia, USA
  • V.S. Morozov
    ODU, Norfolk, Virginia, USA
 
  Next generation magnet systems needed for cooling channels in both neutrino factories and muon colliders will be innovative and complicated. Designing, simulating and optimizing these systems is a challenge. Using COSY INFINITY, a differential algebra-based code, to simulate complicated elements can allow the computation and correction of a variety of higher order effects, such as spherical and chromatic aberrations, that are difficult to address with other simulation tools. As an example, a helical dipole magnet has been implemented and simulated, and the performance of an epicyclic parametric ionization cooling system for muons is studied and compared to simulations made using G4Beamline, a GEANT4 toolkit.  
 
MOP051 End-to-End Simulation of an Inverse Cyclotron for Muon Cooling cyclotron, simulation, injection, collider 193
 
  • K. Paul, E. Cormier-Michel
    Tech-X, Boulder, Colorado, USA
  • T. Hart, D.J. Summers
    UMiss, University, Mississippi, USA
 
  Funding: DOE Office of High-Energy Physics, SBIR DE-FG02-08ER85044
Neutrino factories and muon colliders require significant cooling of the muon beam. Most muon cooling channels are long and expensive single-pass structures, due to the difficulty injecting very large emittance beams into a circular device. Inverse cyclotrons can potentially solve the injection problems associated with other circular cooling channels, and they can potentially provide substantial initial cooling of the beam. We present the first end-to-end (injection to extraction) simulations of an inverse cyclotron for muon cooling, performed with the particle-in-cell code VORPAL. We study the cooling capability of the device as well as potential limitations due to space charge effects and material interactions with the beam.
 
 
MOP055 Robust 6D Muon Cooling in Four-sided Ring Cooler using Solenoids and Dipoles for a Muon Collider collider, dipole, solenoid, lattice 205
 
  • X.P. Ding, D.B. Cline
    UCLA, Los Angeles, California, USA
  • J.S. Berg, H.G. Kirk
    BNL, Upton, Long Island, New York, USA
  • A.A. Garren
    Particle Beam Lasers, Inc., Northridge, California, USA
 
  Funding: DOE Grant No. DE-FG02-92ER40695
We present a four-sided ring cooler that employs both dipoles and solenoids to provide robust 6D muon cooling of large emittance beams in order to design and build a muon collider. Our studies show strong 6D cooling adequate for components of a muon collider front end.
 
 
MOP058 Particle Production in the MICE Beamline target, collider, electron, quadrupole 214
 
  • L. Coney
    UCR, Riverside, California, USA
  • A.J. Dobbs
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
 
  Funding: NSF
The Muon Ionization Cooling Experiment (MICE) will test transverse cooling of a muon beam, satisfying a crucial demonstration step along the path toward creating high intensity muon beams in a Neutrino Factory or Muon Collider. In the last year, MICE has taken a record amount of data to commission the beamline and calibrate the particle identification (PID) detectors. Studies of the MICE beamline and target timing will be discussed, including the use of Time-of-Flight (TOF) detectors to understand the MICE beam content.
 
 
MOP059 Simulations of the Tapered Guggenheim 6d Cooling Channel for the Muon Collider simulation, lattice, collider, extraction 217
 
  • P. Snopok
    IIT, Chicago, Illinois, USA
  • G.G. Hanson
    UCR, Riverside, California, USA
  • R. B. Palmer
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work is supported by the U.S. Department of Energy.
Recent progress in six-dimensional (6D) cooling simulations for the Muon Collider based on the RFOFO ring layout is presented. In order to improve the performance of the cooling channel a tapering scheme is studied that implies changing the parameters such as cell length, magnetic field strength, RF frequency, and the amount of the absorbing material along the cooling channel. This approach allows us to keep the cooling rates high throughout the process. The results of the simulations carried out in G4beamline are presented.
 
 
MOP060 Wedge Absorber Design and Simulation for MICE Step IV simulation, lattice, controls, scattering 220
 
  • C.T. Rogers
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • L. Coney, G.G. Hanson
    UCR, Riverside, California, USA
  • P. Snopok
    IIT, Chicago, Illinois, USA
 
  Funding: Work is supported by the Science and Technology Facilities Council, the U.S. Department of Energy and the U.S. National Science Foundation.
In the Muon Ionization Cooling Experiment (MICE), muons are cooled by passing through material, then through RF cavities to compensate for the energy loss; which reduces the transverse emittance. It is planned to demonstrate longitudinal emittance reduction via emittance exchange in MICE by using a solid wedge absorber in Step IV. Based on the outcome of previous studies, the shape and material of the wedge were chosen. We address here further simulation efforts for the absorber of choice as well as engineering considerations in connection with the absorber support design.
 
 
MOP061 Stability of the MICE Muon Beam Line proton, target, radio-frequency, quadrupole 223
 
  • S.D. Blot
    University of Chicago, Chicago, Illinois, USA
 
  Funding: University of Chicago
The international Muon Ionization and Cooling Exper- iment (MICE) aims to demonstrate transverse beam emit- tance reduction for a muon beam. During the summer of 2010, data was taken using different configurations of the upstream beam line magnets to measure the optical pa- rameters of the muon beam and study the functionality of the beam line itself. Throughout this period of data taking, reference runs were taken with a fixed target configuration, and magnet settings which provide a muon beam with 200 MeV/c momentum and 6π 4D transverse emittance. Time of flight (TOF) detectors were used to measure many of the beam properties including emittance, particle identifi- cation, and profile. Analysis of these reference runs was carried out in order to determine the stability and repro- ducibility of the beam line data. This overall data quality check is essential to ensure the validity of measurements made so that further analysis can be carried out and that the muon beam is suitable for the MICE cooling channel.
 
 
MOP062 Usage of Li-rods for Ionization Cooling of Muons simulation, plasma, collider, focusing 226
 
  • A.N. Skrinsky
    BINP SB RAS, Novosibirsk, Russia
  • T.V. Zolkin
    University of Chicago, Chicago, Illinois, USA
 
  Four different schemes of final ionization cooling are discussed. The first scheme is the straight channel based on lithium rods, which can provide only 4D cooling, but which can be modified to obtain 6D cooling. The helical orbit scheme with decrement redistribution is one such modification. Two other modifications use emittance redistribution and emittance exchange procedures, respectively, to transfer phase-space volume from longitudinal to transverse degrees of freedom (where the transverse degrees of freedom alternate for each successive exchange or redistribution). By emittance redistribution is meant a arbitrary redistribution of phase-space volume from one degree of freedom to another and by emittance exchange is meant a symplectic operation of emittance swap. Estimates of the final emittance, calculations of the technical parameters and simulations of beam movement are presented for each scheme. The study focused on the scheme with emittance exchange because it looks the most promising and simple, both conceptually and in terms of implementation, and it can also extend the cooling process to handle a larger initial emittance relative to the basic straight channel scheme.  
 
MOP087 A Laser-Driven Linear Collider: Sample Machine Parameters and Configuration laser, focusing, collider, linear-collider 262
 
  • E.R. Colby, R.J. England, R.J. Noble
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by Department of Energy contracts DE-AC03-76SF00515 (SLAC) and DE-FG03-97ER41043-III (LEAP).
We present a design concept for an e+ e- linear collider based on laser-driven dielectric accelerator structures, and discuss technical issues that must be addressed to realize such a concept. With a pulse structure that is quasi-CW, dielectric laser accelerators potentially offer reduced beamstrahlung and pair production, reduced event pileup, and much cleaner environment for high energy physics and. For multi-TeV colliders, these advantages become significant.
 
 
MOP113 High Quality Electron Beams Generated in a Laser Wakefield Accelerator electron, laser, plasma, wakefield 307
 
  • W.A. Gillespie
    University of Dundee, Nethergate, Dundee, Scotland, United Kingdom
  • M.P. Anania, C. Aniculaesei, E. Brunetti, S. Cipiccia, B. Ersfeld, M.R. Islam, R.C. Issac, D.A. Jaroszynski, G.G. Manahan, R.P. Shanks, G.H. Welsh, S.M. Wiggins
    USTRAT/SUPA, Glasgow, United Kingdom
  • S.P. Jamison
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • A. MacLeod
    UAD, Dundee, United Kingdom
 
  Funding: The U.K. EPSRC, the EC's Seventh Framework Programme (LASERLAB-EUROPE / LAPTECH, grant agreement no. 228334) and the Extreme Light Infrastructure (ELI) project.
The Advanced Laser-Plasma High-Energy Accelerators towards X-rays (ALPHA-X) programme is developing laser-plasma accelerators for the production of ultra-short electron beams as drivers of incoherent and coherent radiation sources from plasma and magnetic undulators. Here we report on the latest laser wakefield accelerator experiments on the University of Strathclyde ALPHA-X accelerator beam line looking at narrow energy spread electron beams. ALPHA-X uses a 26 TW Ti:sapphire laser (energy 900 mJ, duration 35 fs) focused into a helium gas jet (nozzle length 2 mm) to generate high quality monoenergetic electron beams with central energy in the range 80-180 MeV. The beam is fully characterised in terms of the charge, transverse emittance, energy spread and bunch length. In particular, the energy spectrum (with less than 1% measured energy spread) is obtained using a high resolution magnetic dipole imaging spectrometer.
 
 
MOP121 Experimental Studies on Coherent Synchrotron Radiation in the Emittance Exchange Line at the Fermilab A0 Photoinjector radiation, synchrotron, dipole, synchrotron-radiation 322
 
  • J.C.T. Thangaraj, M.D. Church, H.T. Edwards, A.S. Johnson, A.H. Lumpkin, P. Piot, J. Ruan, J.K. Santucci, Y.-E. Sun, R.M. Thurman-Keup
    Fermilab, Batavia, USA
 
  Future accelerators will employ advanced beam conditioning systems such as emittance exchangers to manipulate high brightness beams. Coherent synchrotron radiation (CSR) in the dipoles could limit the performance of the emittance exchanger. In this paper, we report the experimental and simulation studies on measuring coherent synchrotron radiation and its effects on the beam at the A0 photoinjector in the emittance exchange line. We show how CSR can be used to measure bunch length of the beam. We also report on the diagnostic scheme based on a weak skew quad in the emittance exchange line to study the CSR effects on the beam and other beam dynamics.  
 
MOP128 An Optimized X-band Photoinjector Design for the LLNL MEGa-Ray Project gun, laser, electron, simulation 334
 
  • S.G. Anderson, F. Albert, C.P.J. Barty, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, T.L. Houck, R.A. Marsh
    LLNL, Livermore, California, USA
  • C. Adolphsen, A.E. Candel, E.N. Jongewaard, Z. Li, C. Limborg-Deprey, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou
    SLAC, Menlo Park, 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.
We present an optimized 5 + ½ cell, X-band photoinjector designed to produce 7 MeV, 250 pC, sub-micron emittance electron bunches for the LLNL Mono-Energetic Gamma-Ray (MEGa-Ray) light source. This LLNL/SLAC collaboration modifies a design previously demonstrated to sustain 200 MV/m on-axis accelerating fields*. We discuss the photoinjector operating point, optimized by scaling beam dynamics from S-band photo-guns and by evaluation of the MEGa-Ray source requirements. The RF structure design is presented along with the current status of the photoinjector construction and testing.
*A.E. Vlieks, et al., High Energy Density and High Power RF: 6th Workshop, AIP, CP691, p. 358 (2003).
 
 
MOP132 Wakefield Generation in Compact Rectangular Dielectric-Loaded Structures Using Flat Beams wakefield, simulation, electron, focusing 340
 
  • D. Mihalcea, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • B.M. Cowan, P. Stoltz
    Tech-X, Boulder, Colorado, USA
 
  Funding: This work was supported by the Defense Threat Reduction Agency, Basic Research Award # HDTRA1-10-1-0051, to Northern Illinois University
Wakefields with amplitude in the 10's MV/m range can be routinely generated by passing electron beams through dielectric-loaded structures. The main obstacle in obtaining high field amplitude (in the GV/m range) is the ability to focus the high-peak-current electron beam in the transverse plane to micron level, and to maintain the focusing all the way along the dielectric structure. In this paper we explore the use of a flat, high-peak current, electron beams to be produced at the Fermilab's NML facility to drive dielectric loaded structures. Based on beam dynamics simulation we anticipate that we can obtain flat beams with very small vertical size (under 100 microns) and peak current is in excess of 1 kA. We present simulations of the wakefield generation based on theoretical models and PIC simulations with VORPAL.
 
 
MOP137 Predictive Design and Interpretation of Colliding Pulse Injected Laser Wakefield Experiments laser, plasma, electron, simulation 349
 
  • E. Cormier-Michel, D.L. Bruhwiler, B.M. Cowan, V.H. Ranjibar
    Tech-X, Boulder, Colorado, USA
  • M. Chen, E. Esarey, C.G.R. Geddes, W. Leemans, C.B. Schroeder
    LBNL, Berkeley, California, USA
 
  Funding: Work supported by DOE, NA-22, and Office of Science, HEP via the SciDAC-2 project ComPASS, grant No DE-FC02-07ER41499. Resources of NERSC were used (DOE contract No DE-AC02-05CH11231).
The use of colliding laser pulses to control the injection of plasma electrons into the plasma wake of a laser-plasma accelerator is a promising approach to obtain reproducible and tunable electron bunches with low energy spread and emittance. We present recent particle-in-cell simulations of colliding pulse injection for parameters relevant to ongoing experiments at LBNL. We perform parameter scans in order to determine the best conditions for the production of high quality electron bunches, and compare the results with experimental data. We also evaluate the effect of laser focusing in the plasma channel and of higher order laser mode components on the bunch properties.
 
 
MOP147 Experimental Study of Magnetically Confined Hollow Electron Beams in the Tevatron as Collimators for Intense High-Energy Hadron Beams electron, luminosity, antiproton, gun 370
 
  • G. Stancari, G. Annala, V.D. Shiltsev, D.A. Still, A. Valishev, L.G. Vorobiev
    Fermilab, Batavia, USA
 
  Funding: Fermi Research Alliance, LLC operates Fermilab under Contract DE-AC02-07CH11359 with the US Department of Energy. This work was partially supported by the US LHC Accelerator Research Program (LARP).
Magnetically confined hollow electron beams for controlled halo removal in high-energy colliders such as the Tevatron or the LHC may extend traditional collimation systems beyond the intensity limits imposed by tolerable material damage. They may also improve collimation performance by suppressing loss spikes due to beam jitter and by increasing capture efficiency. A hollow electron gun was designed and tested at Fermilab for this purpose. It was installed in one of the Tevatron electron lenses in the summer of 2010. We present the results of the first tests of the hollow-beam collimation concept on individual 980-GeV antiproton bunches in the Tevatron.
 
 
MOP158 Numerical Study of Plasma Wakefields Excited by a Train of Electron Bunches plasma, wakefield, simulation, electron 391
 
  • Y. Fang, P. Muggli
    USC, Los Angeles, California, USA
  • C. Huang
    LANL, Los Alamos, New Mexico, USA
  • W.B. Mori
    UCLA, Los Angeles, California, USA
 
  Funding: Work supported by the US department of Energy
We study numerically the excitation of plasma wakefields by a train of electron bunches using the UCLA particle-in-cell code Quickpic*. We aim to find an optimal regime that combines both the advantages of linear and non-linear plasma wakefield accelerator. On one hand, the longitudinal electric field excited by individual bunches add as in the linear region, and the transformer ratio can be maximized (i.e. much larger than 2) by adjusting the number of particles in the bunches as well as their distance. On the other hand, the bunches create large wakefield independent of transverse sizes evolution while propagating through the plasma as in the non-linear region. In principle, such a scheme can multiply the energy of the witness bunch following the drive bunch train in a single plasma wakefield accelerating stage. The parameters for electron bunches are chosen based on the current experiment at the Brookhaven National Laboratory Accelerator Test Facility (ATF), where this scheme can be tested. Detailed simulation results will be presented.
* C. Huang, J. Comp. Phys.
 
 
MOP161 Undulator-based Laser Wakefield Accelerator Electron Beam Diagnostic undulator, electron, quadrupole, laser 397
 
  • M.S. Bakeman, E. Esarey, W. Leemans, K. Nakamura, J. Osterhoff, K.E. Robinson, C.B. Schroeder, C. Tóth, J. van Tilborg
    LBNL, Berkeley, California, USA
  • F.J. Grüner, R. Weingartner
    LMU, Garching, Germany
 
  Funding: This work is supported by DTRA and DOE-HEP.
The design and current status of experiments to cou- ple the Tapered Hybrid Undulator (THUNDER) to the Lawrence Berkeley National Laboratory (LBNL) laser plasma accelerator (LPA) to measure electron beam energy spread and emittance are presented.
* W.P. Leemans et al., Nature Physics, Volume 2, Issue 10, pp. 696-699 (2006).
** C.B. Schroeder et al., Proceedings AAC08 Conference (2008).
*** F. Grüner et al., Appl. Phys. B, 86(3):431–435 (2007).
 
 
MOP169 Optical Beam Diagnostics at ELSA synchrotron, quadrupole, diagnostics, sextupole 408
 
  • S. Zander, F. Frommberger, P. Haenisch, W. Hillert, S. Patzelt
    ELSA, Bonn, Germany
 
  Funding: Funded by the DFG within the SFB / TR 16.
The Electron Stretcher Facility ELSA consists of several accelerator stages, the last one being a storage ring providing a beam of polarized electrons of up to 3.5 GeV. At ELSA various diagnostic devices based on synchrotron radiation are installed or planned. A new beamline at the storage ring designed for high resolution diagnostics in the transversal plane will be presented. The measurement setup is sensitive at the UV range of the synchrotron light spectrum. Upgrade measures aiming to extend the diagnostic possibilities to the longitudinal direction will be detailed. In the external beamlines beam currents below 1 nA are delivered to photo production experiments. Beam profiles are detected using dedicated synchrotron light monitors optimized for low intensities. The characteristics of the monitors will be described. In addition, beam parameters derived from the measured profiles at different resonance extraction setups will be shown.
 
 
MOP176 Design of Cavity Beam Quadrupole Moment Monitor at HLS quadrupole, cavity, diagnostics, electron 417
 
  • Q. Luo, Q.K. Jia, B.G. Sun, Z.R. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  Funding: Work supported by the Natural Science Foundation of China, National “985 Project”, China Postdoctoral Science Foundation and “the Fundamental Research Funds for the Central Universities”
Traditional ways to get beam emittance of linacs, such as multi-slits method, are destructive and then not able to be used in on-line beam diagnostics. To meet the requirements of XFEL equipments and improve the quality of electron beam, non-destructive on-line beam emittance measurement methods basing on getting the quadrupole moment of a beam non-destructively are then required. An advanced way to pick up beam information non-destructively with great precision is making use of eigenmodes of resonant cavities. High brightness injector at Hefei light source is used to study FEL based on photocathode RF electron gun. Cavity beam quadrupole moment monitor system designed for the high brightness injector consists of a square pill-box cavity used to pick up quadrupole signal, a cylindrical pill-box reference cavity, a waveguide coupling network that can suppress monopole and dipole signal, and a superheterodyne receiver used as front-end signal processing system. The whole system works at 5.712 GHz. Strength of quadupole magnets is adjust to construct a matrix which can be used to work out beam parameters.
 
 
MOP210 Residual Gas Fluorescence Monitor at RHIC ion, vacuum, injection, heavy-ion 492
 
  • T. Tsang, D.M. Gassner
    BNL, Upton, Long Island, New York, USA
 
  Funding: This work was supported by U.S. Department of Energy under Contract No. DE-AC02-98CH10886.
A residual gas fluorescence beam profile monitor at the relativistic heavy ion collider (RHIC) has successfully recorded vertical beam sizes of Au-ion beams from 3.85 to 100 GeV/n during the 2010 beam runs. Although the fluorescence cross section of Au-ion is sufficiently large, the low residual gas in a typical vacuum chamber of <10-9 torr produces necessary weak fluorescence photons. However, with adequate CCD exposure time, the vertical beam profiles are captured to provide an independent measurement of the RHIC beam size and emittance. This beam diagnostic technique, utilizing the Au-ion beam induced fluorescence from residual gas where hydrogen is still the dominant constituent in nearly all vacuum system, represents a step towards the realization of a truly noninvasive beam monitor for high-energy particle beams.
 
 
MOP219 Initial Beam-Profiling Tests with the NML Prototype Station at the Fermilab A0 Photoinjector radiation, optics, diagnostics, target 510
 
  • A.H. Lumpkin, M.D. Church, R.H. Flora, A.S. Johnson, J. Ruan, J.K. Santucci, V.E. Scarpine, Y.-E. Sun, R.M. Thurman-Keup, M. Wendt
    Fermilab, Batavia, USA
 
  Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Beam-profile diagnostics are being developed for a superconducting (SC) radiofrequency (RF) Test Accelerator that is currently under construction at the New Muon Lab (NML) at Fermilab. The facility’s design goals include the replication of the pulse train proscribed for the International Linear Collider (ILC). An RF photoelectric gun based on the DESY design will generate the beam. In test-beam mode a low-power beam will be characterized with intercepting radiation converter screens: either a 100-micron thick YAG:Ce single crystal scintillator or a 1-micron thin Al optical transition radiation (OTR) foil. This prototype station was constructed by RadiaBeam Technologies under a contract with Fermilab. In both cases the screen surface was normal to the beam direction followed by a downstream 45-degree mirror that directed the radiation into the optical system. The optical system has better than 20 (10) micron rms spatial resolution when covering a vertical field of view of 18(5) mm. These initial tests were performed at the A0 Photoinjector at a beam energy of ~15 MeV and with micropulse charges from 25 to 500 pC for beam sizes of 45 to 250 microns. Example results will be presented.

 
 
MOP224 A Data Acquisition System for Longitudinal Beam Properties in a Rapid Cycling Synchrotron booster, acceleration, synchrotron, instrumentation 522
 
  • J. Steimel, C.-Y. Tan
    Fermilab, Batavia, USA
 
  Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
A longitudinal beam properties, data acquisition system has been commissioned to operate in the Fermilab booster ring. This system captures real time information including beam synchronous phase, bunch length, and coupled bunch instability amplitudes as the beam is accelerated from 400MeV to 8GeV in 33ms. The system uses an off-the-shelf Tektronix oscilloscope running Labview software and a synchronous pulse generator. This paper describes the hardware configuration and the software configuration used to optimize the data processing rate.
 
 
MOP225 Initial Characterization of a Commercial Electron Gun for Profiling High Intensity Proton Beams in Project X electron, proton, gun, solenoid 525
 
  • R.M. Thurman-Keup, A.S. Johnson, A.H. Lumpkin, J.C.T. Thangaraj, D.H. Zhang
    Fermilab, Batavia, USA
  • W. Blokland
    ORNL, Oak Ridge, Tennessee, USA
 
  Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
Measuring the profile of a high intensity proton beam is problematic in that traditional invasive techniques such as flying wires don't survive the encounter with the beam. One alternative is the use of an electron beam as a probe of the charge distribution in the proton beam as was done at the Spallation Neutron Source at ORNL. Here we present an initial characterization of the beam from a commercial electron gun from Kimball Physics, intended for use in the Fermilab Main Injector for Project X.
 
 
MOP226 Transverse Emittance and Phase Space Program Developed for Use at the Fermilab A0 Photoinjector controls, vacuum, background, cavity 528
 
  • R.M. Thurman-Keup, A.S. Johnson, A.H. Lumpkin, J. Ruan
    Fermilab, Batavia, USA
 
  Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The Fermilab A0 Photoinjector is a 16MeV high intensity, high brightness electron Linac developed for advanced accelerator R&D. One of the key parameters for the electron beam is the transverse beam emittance. Here we report on a newly developed MATLAB based GUI program used for transverse emittance measurements using the multi-slit technique. This program combines the image acquisition and post-processing tools for determining the transverse phase space parameters with uncertainties.
 
 
MOP250 NSLS-II High Level Application Infrastructure and Client API Design EPICS, controls, quadrupole, monitoring 582
 
  • G. Shen, K. Shroff, L. Yang
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work performed under auspices of the U.S. Department of Energy under Contract No. DE-AC02-98CH10886 with Brookhaven Science Associates, LLC.
The beam commissioning software framework of NSLS-II project adopts a client/server based architecture to replace the more traditional monolithic high level application approach. It is an open structure platform, and we try to provide a narrow API set for client application. With this narrow API, existing applications developed in different language under different architecture could be ported to our platform with small modification. This paper describes a detailed client API design, and latest progress.
 
 
MOP252 Server Development for NSLS-II Physics Applications and Performance Analysis EPICS, controls, synchrotron, synchrotron-radiation 585
 
  • G. Shen, M.R. Kraimer
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work performed under auspices of the U.S. Department of Energy under Contract No. DE-AC02-98CH10886 with Brookhaven Science Associates, LLC.
The beam commissioning software framework of NSLS-II project adopts a client/server based architecture to replace the more traditional monolithic high level application approach. The server development is ongoing, and adopts a sourceforge open project so-called epics-pvdata, which consists of pvData, pvAccess, pvEngine, and pvService. Some services have being demonstrated as one service under pvService module such as itemFinder service, gather service, and lattice manager, and each service runs as one standalone server using pvData to store in-memory transient data, pvService to transfer data over network, and pvEngine as service engine. This paper describes a detailed development, latest progress, and performance analysis.
 
 
TUOAN1 SuperB: Next-Generation e+e B-factory Collider solenoid, luminosity, quadrupole, collider 690
 
  • A. Novokhatski, K.J. Bertsche, A. Chao, Y. Nosochkov, J.T. Seeman, M.K. Sullivan, U. Wienands, W. Wittmer
    SLAC, Menlo Park, California, USA
  • M.A. Baylac, O. Bourrion, N. Monseu, C. Vescovi
    LPSC, Grenoble, France
  • S. Bettoni
    CERN, Geneva, Switzerland
  • M.E. Biagini, R. Boni, M. Boscolo, T. Demma, A. Drago, M. Esposito, S. Guiducci, M.A. Preger, P. Raimondi, S. Tomassini, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  • A.V. Bogomyagkov, E.B. Levichev, S.A. Nikitin, P.A. Piminov, D.N. Shatilov, S.V. Sinyatkin, P. Vobly
    BINP SB RAS, Novosibirsk, Russia
  • B. Bolzon, L. Brunetti, A. Jeremie
    IN2P3-LAPP, Annecy-le-Vieux, France
  • A. Chancé
    CEA, Gif-sur-Yvette, France
  • P. Fabbricatore, S. Farinon, R. Musenich
    INFN Genova, Genova, Italy
  • S.M. Liuzzo, E. Paoloni
    University of Pisa and INFN, Pisa, Italy
  • I.N. Okunev
    BINP, Novosibirsk, Russia
  • F. Poirier, C. Rimbault, A. Variola
    LAL, Orsay, France
 
  Funding: Work supported by the U.S. Department of Energy under contract DE-AC02-76SF00515.
The SuperB international team continues to optimize the design of an electron-positron collider, which will allow the enhanced study of the origins of flavor physics. The project combines the best features of a linear collider (high single-collision luminosity) and a storage-ring collider (high repetition rate), bringing together all accelerator physics aspects to make a very high luminosity of 1036 cm-2 s-1. This asymmetric-energy collider with a polarized electron beam will produce hundreds of millions of B-mesons at the Y(4S) resonance. The present design is based on extremely low emittance beams colliding at a large Piwinski angle to allow very low ßy* without the need for ultra short bunches. Use of crab-waist sextupoles will enhance the luminosity, suppressing dangerous resonances and allowing for a higher beam-beam parameter. The project has flexible beam parameters, improved dynamic aperture, and spin-rotators in the Low Energy Ring for longitudinal polarization of the electron beam at the Interaction Point. Optimized for best colliding-beam performance, the facility may also provide high-brightness photon beams for synchrotron-radiation applications.
 
slides icon Slides TUOAN1 [9.378 MB]  
 
TUOAS1 Tutorial on Accelerator-Based Light Sources radiation, electron, dipole, undulator 702
 
  • M. Borland
    ANL, Argonne, 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.
Accelerator-based light sources are some of the largest and most successful scientific user facilities in existence, serving tens of thousands of users each year. These important facilities enable research in diverse fields, including biology, pharmaceuticals, energy conservation and production, data storage, and archaeology. In this tutorial, we briefly review the history of accelerator-based light sources. We present an overview of the different types of accelerator-based light sources, including a description of their various operating principles, as well as a discussion of measures of performance. Technical challenges of current and future light sources are also reviewed.
 
slides icon Slides TUOAS1 [1.421 MB]  
 
TUOBS2 Cornell ERL Research and Development electron, FEL, linac, gun 729
 
  • C.E. Mayes, I.V. Bazarov, S.A. Belomestnykh, D.H. Bilderback, M.G. Billing, J.D. Brock, E.P. Chojnacki, J.A. Crittenden, L. Cultrera, J. Dobbins, B.M. Dunham, R.D. Ehrlich, M. P. Ehrlichman, E. Fontes, C.M. Gulliford, D.L. Hartill, G.H. Hoffstaetter, V.O. Kostroun, F.A. Laham, Y. Li, M. Liepe, X. Liu, F. Löhl, A. Meseck, A.A. Mikhailichenko, H. Padamsee, S. Posen, P. Quigley, P. Revesz, D.H. Rice, D. Sagan, V.D. Shemelin, E.N. Smith, K.W. Smolenski, A.B. Temnykh, M. Tigner, N.R.A. Valles, V. Veshcherevich, Y. Xie
    CLASSE, Ithaca, New York, USA
  • S.S. Karkare, J.M. Maxson
    Cornell University, Ithaca, New York, USA
 
  Funding: Supported by NSF award DMR-0807731.
Energy Recovery Linacs (ERLs) are proposed as drivers for hard X-ray sources because of their ability to produce electron bunches with small, flexible cross sections and short lengths at high repetition rates. The advantages of ERL lightsources will be explained, and the status of plans for such facilities will be described. In particular, Cornell University plans to build an ERL light source, and the preparatory research for its construction will be discussed. This will include the prototype injector for high current CW ultra-low emittance beams, superconducting CW technology, the transport of low emittance beams, halo formation from intrabeam scattering, the mitigation of ion effects, the suppression of instabilities, and front to end simulations. Several of these topics could become important for other modern light source projects, such as SASE FELs, HGHG FELs, and XFELOs.
 
slides icon Slides TUOBS2 [5.632 MB]  
 
TUOBS4 Challenge of MAX IV Towards a Multi-Purpose Highly Brilliant Light Source linac, lattice, storage-ring, vacuum 737
 
  • M. Eriksson, J. Ahlbäck, Å. Andersson, M.A.G. Johansson, D. Kumbaro, S.C. Leemann, C. Lenngren, P. Lilja, F. Lindau, L.-J. Lindgren, L. Malmgren, J.H. Modéer, R. Nilsson, M. Sjöström, J. Tagger, P.F. Tavares, S. Thorin, E.J. Wallén, S. Werin
    MAX-lab, Lund, Sweden
  • B. Anderberg
    AMACC, Uppsala, Sweden
  • L.O. Dallin
    CLS, Saskatoon, Saskatchewan, Canada
 
  A design study of the MAX-IV light source complex in Sweden has been completed. One of MAX-IV's main light sources, a 3 GeV storage ring, is designed to achieve a natural emittance of ~0.2 nm rad. The facility will also provide SASE-XFEL using a 3 GeV high performance linear accelerator. The speaker will discuss facility targets, the concept and accelerator design, and show some possibilities approaching two-dimensional diffraction-limited X-ray generation at MAX-IV.  
slides icon Slides TUOBS4 [6.719 MB]  
 
TUOCN3 Application of the Eigen-Emittance Concept to Design Ultra-Bright Electron Beams electron, cathode, laser, free-electron-laser 752
 
  • L.D. Duffy, K. Bishofberger, B.E. Carlsten, S.J. Russell, N.A. Yampolsky
    LANL, Los Alamos, New Mexico, USA
  • A. Dragt
    UMD, College Park, Maryland, USA
  • R.D. Ryne
    LBNL, Berkeley, California, USA
 
  Funding: We acknowledge the support of the U.S. Department of Energy through the LANL/LDRD Program.
Using correlations at the cathode to tailor the beam’s eigen-emittances is a recent concept made useful by the symplectic nature of Hamiltonian systems. While introducing correlations does not change the overall 6-dimensional phase space volume, it can change the partitioning of this volume into the longitudinal and two transverse emittances, which become the eigen-emittances if the initial correlations are removed. In principle, this technique can be used to generate beams with highly asymmetric emittances, such as those needed for the next generation of very hard X-ray free-electron lasers. Based on linear correlations, the applicability of this approach is limited by the magnitude of nonlinear effects in photoinjectors. We review the eigen-emittance concept and present a linear eigen-emittance design leading to a highly partitioned, and transversely ultra-bright, electron beam. We also present numerical tools to examine the evolution of the eigen-emittances in realistic accelerator structures and results indicating how much partitioning is practical.
 
slides icon Slides TUOCN3 [0.530 MB]  
 
TUOCN4 Subpicosecond Electron Bunch Train Production Using a Phase-Space Exchange Technique quadrupole, dipole, electron, cavity 755
 
  • Y.-E. Sun, A.S. Johnson, A.H. Lumpkin, J. Ruan, R.M. Thurman-Keup
    Fermilab, Batavia, USA
  • T.J. Maxwell, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
 
  Funding: The work was supported by the Fermi Research Alliance, LLC under the DOE Contract No. DE-AC02-07CH11359, and by Northern Illinois University under the DOE Contract No. DE-FG02-08ER41532.
Our recent experimental demonstration of a photoinjector electron bunch train with sub-picosecond structures is reported in this paper. The experiment is accomplished by converting an initially horizontal beam intensity modulation into a longitudinal phase space modulation, via a beamline capable of exchanging phase-space coordinates between the horizontal and longitudinal degrees of freedom. The initial transverse modulation is produced by intercepting the beam with a multislit mask prior to the exchange. We also compare our experimental results with numerical simulations.
 
slides icon Slides TUOCN4 [1.761 MB]  
 
TUOCN5 Theoretical Study of Transverse-Longitudinal Emmittance Coupling lattice, coupling, focusing, plasma 758
 
  • H. Qin, R.C. Davidson
    PPPL, Princeton, New Jersey, USA
  • J.J. Barnard
    LLNL, Livermore, California, USA
  • M. Chung
    Handong Global University, Pohang, Republic of Korea
  • T.-S.F. Wang
    LANL, Los Alamos, New Mexico, USA
 
  Funding: Research supported by the U.S. Department of Energy.
The effect of a weakly coupled periodic lattice in terms of achieving emittance exchange between the transverse and longitudinal directions is investigated using the generalized Courant-Snyder theory for coupled lattices.
* H. Qin, M. Chung, and R. C. Davidson, PRL. 103, 224802 (2009).
** H. Qin and R. C. Davidson, PRST-AB 12, 064001 (2009).
 
slides icon Slides TUOCN5 [2.995 MB]  
 
TUOCS3 Status of the ALS Upgrade lattice, brightness, insertion, insertion-device 769
 
  • C. Steier, B.J. Bailey, A. Biocca, A.T. Black, D. Colomb, N. Li, A. Madur, S. Marks, H. Nishimura, G.C. Pappas, G.J. Portmann, S. Prestemon, D. Robin, S.L. Rossi, F. Sannibale, T. Scarvie, D. Schlueter, C. Sun, W. Wan
    LBNL, Berkeley, California, USA
 
  Funding: Work supported by the U.S. Department of Energy under Contract No. DE-AC02-05CH11231
The Advanced Light Source (ALS) at Berkeley Lab is one of the earliest 3rd generation light sources. Over the years substantial upgrades have been implemented to keep the facility at the forefront of soft x-ray sources. The most recent one is a multi-year upgrade, that includes new and replacement x-ray beamlines, a replacement of many of the original insertion devices and many upgrades to the accelerator. The accelerator upgrade that affects the ALS performance most directly is the ALS brightness upgrade, which will reduce the horizontal emittance from 6.3 to 2.2 nm. This will result in a brightness increase by a factor of three for bend magnet beamlines and at least a factor of two for insertion device beamlines and will keep the ALS competitive with newer sources.
 
slides icon Slides TUOCS3 [4.970 MB]  
 
TUOCS4 Upgrade of Accelerator Complex at Pohang Light Source Facility (PLS-II) storage-ring, linac, vacuum, insertion 772
 
  • K.R. Kim, H.-S. Kang, C. Kim, D.E. Kim, S.H. Kim, S.-C. Kim, H.-G. Lee, J.W. Lee, S.H. Nam, C.D. Park, S.J. Park, S. Shin
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  Funding: This upgrade project of PLS-II is supported by MEST, in Korea
In order to meet the domestic Korean synchrotron user’s requirements demanding high beam stability and extended photon energies, PLS-II upgrade program has been launched in January 2009 through a 3-year project plan. PLS-II storage ring is newly designed a modified achromatic version of Double Bend Achromat (DBA) to achieve almost twice as many straight sections as the current PLS (TBA) with a design goal of the natural emittance of 5.8 nm·rad, 3.0 GeV beam energy and 400 mA beam current. In the PLS-II, the top-up injection using full energy linac of 3.0 GeV beam energy will be routinely operated for higher stable photon beam as well and therefore the production of hard x-ray undulator radiation of 8 to13 keV is anticipated to allow for more competitive scientific research activities namely x-ray bio-imaging and protein crystallography.
 
slides icon Slides TUOCS4 [17.914 MB]  
 
TUOCS7 Design of an Ultimate Storage Ring for Future Light Source storage-ring, resonance, FEL, dynamic-aperture 781
 
  • Y.C. Jing, S.-Y. Lee
    IUCEEM, Bloomington, Indiana, USA
  • P.E. Sokol
    IUCF, Bloomington, Indiana, USA
 
  Ultimate storage ring (USR) with natural emittance comparable to diffractive limit is becoming a compatible candidate for next generation hard X-ray light source. When FEL technique is employed, it can deliver a high quality beam with very high brightness compared to 3rd generation light sources and transverse coherence which facilitates the power growth. In this paper, we propose a design of a 5GeV USR with emittance at 10pm for both planes. A lattice of nBA type is used and combined function magnet is employed to make a compact storage ring.  
slides icon Slides TUOCS7 [1.746 MB]  
 
TUODN3 Beam Dynamics Studies of Parallel-Bar Deflecting Cavities cavity, simulation, electron, extraction 790
 
  • S. Ahmed, J.R. Delayen, A.S. Hofler, G.A. Krafft, M. Spata, M.G. Tiefenback
    JLAB, Newport News, Virginia, USA
  • K.B. Beard
    Muons, Inc, Batavia, USA
  • K.A. Deitrick
    RPI, Troy, New York, USA
  • S.D. Silva
    ODU, Norfolk, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
We have performed three-dimensional simulations of beam dynamics for parallel-bar transverse electromagnetic mode (TEM) type RF separators: normal- and superconducting. The compact size of these cavities as compared to conventional TM110 type structures is more attractive particularly at low frequency. Highly concentrated electromagnetic fields between the parallel bars provide strong electrical stability to the beam for any mechanical disturbance. An array of eight 2-cell normal conducting cavities or a one- or two-cell superconducting structure are enough to produce the required vertical displacement at the Lambertson magnet. Both the normal and superconducting structures show very small emittance dilution due to the vertical kick of the beam.
 
slides icon Slides TUODN3 [1.558 MB]  
 
TUODN4 Dynamic Aperture Optimization using Genetic Algorithms lattice, dynamic-aperture, sextupole, storage-ring 793
 
  • C. Sun, H. Nishimura, D. Robin, C. Steier, W. Wan
    LBNL, Berkeley, California, USA
 
  Genetic Algorithm is successfully applied to optimize dynamic aperture of lattices for ALS future upgrades. It is demonstrated that the optimization using total diffusion rate as objective has a better performance than the one using dynamic aperture area. The linear and non-linear properties of the lattice are optimized simultaneously, and trade-offs are found among the small emittance, low-beta function and large dynamic aperture. These trade-offs can provide us a guideline to choose a candidate lattice for ALS future upgrades.  
slides icon Slides TUODN4 [1.781 MB]  
 
TUODS1 MaRIE X-Ray Free-Electron Laser Pre-Conceptual Design electron, photon, undulator, cathode 799
 
  • B.E. Carlsten, C.W. Barnes, K. Bishofberger, L.D. Duffy, C.E. Heath, Q.R. Marksteiner, D.C. Nguyen, S.J. Russell, R.L. Sheffield, E.I. Simakov, N.A. Yampolsky
    LANL, Los Alamos, New Mexico, USA
  • R.D. Ryne
    LBNL, Berkeley, California, USA
 
  Funding: This work is supported by the U.S. Department of Energy through the LANL/LDRD and MaRIE programs.
The proposed Matter-Radiation Interactions in Extremes (MaRIE) facility at the Los Alamos National Laboratory will include a 50-keV X-Ray Free-Electron Laser (XFEL), a significant extension from planned and existing XFEL facilities. To prevent an unacceptably large energy spread arising from energy diffusion, the electron beam energy should not exceed 20 GeV, which puts a significant constraint on the beam emittance. To achieve a sufficiently high gradient of 50 MV/m, an rf frequency of 11.424 GHz is considered. A 100-pC baseline design is presented along with advanced technology options to increase the photon flux and to generate longitudinal coherency through single-bunch optical seeding, pre-bunching the electron beam, and combinations of these techniques.
 
slides icon Slides TUODS1 [0.751 MB]  
 
TUP009 A Computational Model for Muons Passing Gas and Plasma Targets: Beam Emittance. target, scattering, simulation, collective-effects 823
 
  • A. Samolov, A.L. Godunov
    ODU, Norfolk, Virginia, USA
 
  A good understanding of interaction of muon beams with gas targets is crucial for attaining high acceleration gradients in gas pressured RF cavities. This physics includes a number of challenging problems. Our objective has been to develop a computational model for studying the most important effects within the same level of accuracy. The computational model simulates scattering of a bunch of charged particles on multiple atomic, molecular and ionic centers. The interaction potentials have been calculated using Hartree-Fock method for atomic targets, and Molecular Orbital method for molecular targets. Target particles are populated randomly to simulate either a gas in a pressured RF cavity with a particular material density, or liquid hydrogen. In the present work the following effects on beam emittance have been studied: effect of multiple scattering (comparing to single particle tracking models), effect of various degree of target ionization (beam-plasma interaction), space charge screening in plasma, effect of strong magnetic fields. Our preliminary results demonstrate that the degree of plasma ionization has a strong effect of the beam emittance.  
 
TUP014 Broad-band Beam Chopper for a CW Proton Linac at Fermilab kicker, coupling, rfq, linac 838
 
  • N. Solyak, E. Gianfelice-Wendt, V.A. Lebedev, S. Nagaitsev, D. Sun
    Fermilab, Batavia, USA
 
  The specifications and the initial conceptual ides for a broad-band proton chopper for a Fermilab Project X linac will be presented. The chopper will form bunch patterns required by physics experiments and will work with downstream beam splitter, allowing for a variable bunch pattern to be delivered to up to three experiment concurrently.  
 
TUP018 Design of a S-Band 4,5 Cells RF Gun gun, simulation, electron, booster 850
 
  • R. Roux, C. Bruni, H. Monard
    LAL, Orsay, France
 
  Most of radio-frequency (RF) photo-injectors operating in the world are made of 1,5 or 2,5 cells. Although excellent qualities of electron beam have been obtained there are few cases where the extension of the number of cells could be interesting. For instance, the small accelerators with energy in the range of 10-20 MeV which are mostly based on the operation of a RF gun with a booster. One single RF gun fulfilling both functions would simplify the construction and the cost of such machines. The inherent simplicity would also ensure a better reliability. We will present 2D and 3D RF simulations of this 4,5 cells RF photo-injector. In addition we will compare through beam dynamics simulations, with the PARMELA and ASTRA codes, the performances of this gun with respect of classical design based on the couple RF gun plus booster.  
 
TUP023 X-Band RF Photoinjector Research and Development at LLNL electron, cathode, coupling, simulation 859
 
  • R.A. Marsh, S.G. Anderson, C.P.J. Barty, G.K. Beer, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, T.L. Houck
    LLNL, Livermore, California, USA
  • C. Adolphsen, A.E. Candel, T.S. Chu, E.N. Jongewaard, Z. Li, C. Limborg-Deprey, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou
    SLAC, Menlo Park, 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, and funded by DHS Domestic Nuclear Detection Office
In support of Compton scattering gamma-ray source efforts at LLNL, a multi-bunch test station is being developed to investigate accelerator optimization for future upgrades. This test station will enable work to explore the science and technology paths required to boost the current mono-energetic gamma-ray (MEGa-Ray) technology a higher effective repetition rate, potentially increasing the average gamma-ray brightness by two orders of magnitude. The test station will consist of a 5.5 cell X-band rf photoinjector, single accelerator section, and beam diagnostics. Beam quality must be exceedingly high in order to produce narrow-bandwidth gamma-rays, requiring a robust state of the art photoinjector. The photoinjector will be a high gradient (200 MV/m cathode field) standing wave structure, featuring a dual feed racetrack coupler, elliptical irises, and an optimized first cell length. Detailed design of the rf photoinjector for this test station is complete, and will be presented with modeling simulations, and layout plans.
 
 
TUP074 Experiments on HOM Spectrum Manipulation in a 1.3 GHz ILC SC Cavity HOM, cavity, linac, resonance 958
 
  • T.N. Khabiboulline, N. Solyak, V.P. Yakovlev
    Fermilab, Batavia, USA
 
  Superconducting cavities with high operating Q will be installed in the Project-X, a superconducting linac, which is under development at Fermilab. Possibility of cavity design without HOM couplers considered. Rich spectrum of the beam and large number of cavities in ProjectX linac can result to resonance excitation of some high order modes with high shunt impedance. Under scope of study of High Order Modes (HOM) damping the manipulation with HOM spectrum in cold linac is considered. Results of detuning HOM spectrum of 1.3 GHz cavities at 2K in Horizontal Test Station of Fermilab are presented. Possible explanation of the phenomena is discussed.  
 
TUP132 50 MW X-Band RF System for a Photoinjector Test Station at LLNL klystron, electron, linac, high-voltage 1082
 
  • T.L. Houck, S.G. Anderson, C.P.J. Barty, G.K. Beer, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, R.A. Marsh
    LLNL, Livermore, California, USA
  • C. Adolphsen, A.E. Candel, T.S. Chu, E.N. Jongewaard, Z. Li, T.O. Raubenheimer, S.G. Tantawi, A.E. Vlieks, F. Wang, J.W. Wang, F. Zhou
    SLAC, Menlo Park, 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, and funded by DHS Domestic Nuclear Detection Office.
In support of x-band photoinjector development efforts at LLNL, a 50 MW test station is being constructed to investigate structure and photocathode optimization for future upgrades. A SLAC XL-4 klystron capable of generating 50 MW, 1.5 microsecond pulses will be the high power RF source for the system. The timing of the laser pulse on the photocathode with the applied RF field places very stringent requirements on phase jitter and drift. To achieve these requirements, the klystron will be powered by a state of the art, solid-state, high voltage modulator. The 50 MW of RF power will be divided between the photoinjector and a traveling wave accelerator section. A high power phase shifter is located between the photoinjector and accelerator section to adjust the phasing of the electron bunches with respect to the accelerating field. A variable attenuator is included on the input of the photoinjector. The distribution system including the various x-band components is being designed and constructed. In this paper, we will present the design, layout, and status of the RF system.
 
 
TUP173 Progress on the Modeling and Modification of the MICE Superconducting Spectrometer Solenoids solenoid, radiation, simulation, focusing 1151
 
  • S.P. Virostek, M.A. Green, T.O. Niinikoski, S. Prestemon, M.S. Zisman
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the Office of Science, U.S. Department of Energy under DOE contract number DE-AC02-05CH11231.
The Muon Ionization Cooling Experiment (MICE) is an international effort sited at Rutherford Appleton Laboratory (RAL) in the UK that will demonstrate ionization cooling in a section of realistic cooling channel using a muon beam. The spectrometer solenoids are an identical pair of five-coil superconducting magnets that will provide a 4-tesla uniform field region at each end of the cooling channel. Scintillating fiber trackers within each of the 400-mm diameter magnet bore tubes will measure the emittance of the beam as it enters and exits the cooling channel. Each of the 3-meter long magnets incorporates a three-coil spectrometer magnet section and a two-coil section that matches the solenoid uniform field into the MICE cooling channel. The cold mass, radiation shield and leads are kept cold by means of a series of two-stage cryocoolers and one single-stage cryocooler. Various thermal, electrical and magnetic analyses are being carried out in order to develop design improvements related to magnet cooling and reliability. The key features of the spectrometer solenoid magnets are presented along with some of the details of the analyses.
 
 
TUP200 Spatial and Temporal Shaping of Picoseconds Drive Laser in Photocathode RF Gun laser, gun, polarization, electron 1196
 
  • Z.G. He, Q.K. Jia
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  In this paper, we present experimental spatial and temporal drive laser shaping results by using of a pi-shaper sample and an interferometer setup pulse stacking system. Based on the spatial and temporal shaping results, a scheme for quasi-ellipsoidal shaping and the evolution of critical parameters are also studied.  
 
TUP240 Coil Energizing Patterns for an Electromagnetic Variably Polarizing Undulator polarization, undulator, wiggler, radiation 1277
 
  • R.J. Dejus, M.S. Jaski, E.R. Moog
    ANL, Argonne, USA
  • S. Sasaki
    HSRC, Higashi-Hiroshima, Japan
 
  Funding: The submitted manuscript has been created by UChicago Argonne, LLC, Operator of Argonne National Laboratory (“Argonne”).
A new electromagnetic insertion device optimized for producing intense soft x-rays of variable polarization is under construction at the Advanced Photon Source. Most of the coil packs are powered by a main power supply; a few are powered separately so that magnetic fields at certain pole positions can be different. The undulator radiation depends sensitively on the chosen magnetic field pattern, and higher spectral harmonics may be shifted in energy. For some beamline experiments, it is important to reduce the so-called higher-order contamination to increase the signal-to-noise ratio. We present spectra and power densities calculated directly from realistic magnetic fields and discuss coil energizing patterns.
Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
 
 
TUP241 End-Field Analysis and Implementation of Correction Coils for a Short-Period NbTi Superconducting Undulator undulator, simulation, photon, alignment 1280
 
  • C.L. Doose, M. Kasa, S.H. Kim
    ANL, Argonne, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357.
A short period superconducting undulator (SCU) is being developed at the Advanced Photon Source (APS). The on-axis field of the prototype 1.6-cm period 42-pole SCU0 was measured with a cryogenic Hall probe system. Typical permanent magnet undulators provide end-field correction by decreasing the strength of the magnets on both ends of each jaw. In the case of the SCU0, a set of correction coils was wound on the two end grooves of each of the steel cores along with the main coils to provide the required end fields. These correction coils were connected in series and energized with one power supply to provide simple and symmetrical operation. The measured phase errors of the SCU0 were below 2 degrees rms without any local magnetic tuning of the device.
 
 
TUP293 ESTB: A New Beam Test Facility at SLAC kicker, hadron, electron, linac 1373
 
  • M.T.F. Pivi, H. Fieguth, C. Hast, R.H. Iverson, J. Jaros, R.K. Jobe, L. Keller, D.R. Walz, S.P. Weathersby, M. Woods
    SLAC, Menlo Park, California, USA
 
  End Station Test Beam (ESTB) is an end beam line at SLAC using a small fraction of the 13.6 GeV electron beam from the Linac Coherent Light Source (LCLS), restoring test beam capabilities in the large End Station A (ESA) experimental hall. In the past, 18 institutions participated in the ESA program at SLAC. The ESTB program will provide one of a kind test beams essential for developing accelerator instrumentation and accelerator R&D, performing particle and astroparticle physics detector research, linear collider machine and detector interface (MDI) R&D, developing of radiation-hard detectors and material damage studies with several distinctive features. At this stage, 4 new kicker magnets are added to divert 5 Hz of LCLS beam to the A-line, a new beam dump is installed and a new PPS system is built in ESA. In a second stage, a secondary hadron target will be installed, able to produce pions up to about 12 GeV/c at 1 particle/pulse. In summary, ESTB provides a new test facility for LHC detector upgrades, Super B Factory detector development, and Linear Collider accelerator and detector R&D with the first beam expected by June and users starting operations by July 2011.  
 
WEOBS5 Status of the Short-Pulse X-ray Project (SPX) at the Advanced Photon Source (APS) cavity, feedback, cryomodule, impedance 1427
 
  • R. Nassiri, N.D. Arnold, G. Berenc, M. Borland, D.J. Bromberek, Y.-C. Chae, G. Decker, L. Emery, J.D. Fuerst, A.E. Grelick, D. Horan, F. Lenkszus, R.M. Lill, V. Sajaev, T.L. Smith, G.J. Waldschmidt, G. Wu, B.X. Yang, A. Zholents
    ANL, Argonne, USA
  • J.M. Byrd, L.R. Doolittle, G. Huang
    LBNL, Berkeley, California, USA
  • G. Cheng, G. Ciovati, J. Henry, P. Kneisel, J.D. Mammosser, R.A. Rimmer, L. Turlington, H. Wang
    JLAB, Newport News, Virginia, USA
 
  Funding: Work at Argonne is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11354.
The Advanced Photon Source Upgrade project (APS-U) at Argonne includes implementation of Zholents’* deflecting cavity scheme for production of short x-ray pulses. This is a joint project between Argonne National Laboratory, Thomas Jefferson National Laboratory, and Lawrence Berkeley National Laboratory. This paper describes performance characteristics of the proposed source and technical issues related to its realization. Ensuring stable APS storage ring operation requires reducing quality factors of these modes by many orders of magnitude. These challenges reduce to those of the design of a single-cell SC cavity that can achieve the desired operating deflecting fields while providing needed damping of all these modes. The project team is currently prototyping and testing several promising designs for single-cell cavities with the goal of deciding on a winning design in the near future.
*A. Zholents et al., NIM A 425, 385 (1999).
 
slides icon Slides WEOBS5 [1.730 MB]  
 
WEOCN1 Laser Based Diagnostics for Measuring H- Beam Parameters laser, diagnostics, ion, linac 1433
 
  • Y. Liu, A.V. Aleksandrov, W. Blokland, C. Deibele, C.D. Long, A.A. Menshov, J. Pogge, A. Webster, A.P. Zhukov
    ORNL, Oak Ridge, Tennessee, USA
  • R.A. Hardin
    ORNL RAD, Oak Ridge, Tennessee, USA
 
  Funding: sponsored by the Division of Materials Science, U.S. Department of Energy, under contract number DE-AC05-96OR22464 with UT-Battelle Corporation for Oak Ridge National Laboratory
In recent years, a number of laser based H- beam diagnostics systems have been developed in the Spallation Neutron Source (SNS). This talk reviews three types of laser based diagnostics at SNS: the laser wire profile monitors at superconducting linac (SCL), the laser transverse emittance scanner at high energy beam transport (HEBT), and the laser bunch shape monitor at medium energy beam transport (MEBT). Measurement performance will be reported and major technical challenges in the design, implementation, and operation of laser based diagnostics at accelerator facilities will be addressed.
 
slides icon Slides WEOCN1 [4.710 MB]  
 
WEODN2 KEK ATF Beam Instrumentation Program laser, feedback, cavity, kicker 1480
 
  • N. Terunuma
    KEK, Ibaraki, Japan
 
  The Accelerator Test Facility (ATF) in KEK is a research center for studies on issues concerning the injector, damping ring, and beam delivery system for the ILC. It comprises a multibunch-capable RF gun, a 1.3 GeV electron linac, a damping ring, and a test beam line for ILC final focus system (ATF2). Goals of ATF/ATF2 are the achievement of 2 pm vertical emittance, demonstration of a ILC like multi-bunch extraction, achievement of the 37 nm vertical beam size, and stabilization of such beam in a few nano meter level. These targets are supported by R&Ds, such as upgrade of DR BPMs, fast kicker, cavity BPMs, laser-wire, intra-train feedback system (FONT) and a Laser-fringe beam size monitor. To continue providing vital opportunities for accelerator development with the world community, the international collaboration was established.  
slides icon Slides WEODN2 [7.631 MB]  
 
WEODN4 NSLS-II Fast Orbit Feedback with Individual Eigenmode Compensation feedback, controls, EPICS, storage-ring 1488
 
  • Y. Tian, L.-H. Yu
    BNL, Upton, Long Island, New York, USA
 
  This paper presents the NSLS-II fast orbit feedback system with individual eigenmode compensation. The fast orbit feedback system is a typical multiple-input and multiple-output (MIMO) system. Traditional singular value decomposition (SVD) based fast orbit feedback systems treat each eigenmode the same and the same compensation algorithm is applied to all the eigenmodes. In reality, a MIMO system will have different frequency responses for different eigenmodes and thus it is desirable to design different compensation for each eigenmode. The difficulty with this approach comes from the large amount of computation that needs to be done within the time budget of the orbit feedback system. We designed and implemented the NSLS-II fast orbit feedback (FOFB) system with individual eigenmode compensation by taking advantage of the parallel computation capability of field programmable gate array (FPGA) chips.  
slides icon Slides WEODN4 [1.064 MB]  
 
WEP006 Study of Effects of Failure of Beamline Elements & Their Compensation in CW Superconducting Linac cavity, linac, solenoid, beam-losses 1513
 
  • A. Saini, K. Ranjan
    University of Delhi, Delhi, India
  • C.S. Mishra, N. Solyak, V.P. Yakovlev
    Fermilab, Batavia, USA
 
  Project-X is the proposed high intensity proton facility to be built at Fermilab, US. The first stage of the Project-X consists of superconducting Linac which will be operated in continuous wave (CW) mode to accelerate the beam from 2.5 MeV to 3 GeV. The operation at CW mode puts high tolerances on the beam line components, particularly on radiofrequency (RF) cavity. The failure of beam line elements at low energy is very critical as it results in mis-match of the beam with the following sections due to different beam parameters than designed parameter. It makes the beam unstable which causes emittance dilution, and ultimately results in beam losses. In worst case, it could affect the reliability of the machine and may lead to the shutdown of the Linac to replace the failed elements. Thus, it is important to study these effects and their compensation to get smooth beam propagation in Linac. This paper describes the results of study performed for the failure of RF cavity & solenoid in SSR0 section.  
 
WEP016 Evaluating the Dynamic Aperture for the New RHIC 250-GeV Polarized Proton Lattice dynamic-aperture, lattice, proton, luminosity 1528
 
  • X. Gu, W. Fischer, H. Huang, Y. Luo, S. Tepikian
    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.
To increase luminosity in the Relativistic Heavy Ion Collider’s (RHIC’s) polarized proton 250 GeV operations, we are considering reducing beta* to 0.65 m at the interaction points (IPs), and increasing bunch intensity. The new working point near the 2/3 integer will used on the ramp to preserve polarization. In addition, we plan to adjust the betatron-phase advances between IP6 and IP8 to (k+1/2)*PI so to lower the dynamic beta-beat from the beam-beam interaction. The effects of all these changes will impact the dynamic aperture, and hence, it must be evaluated carefully. In this article, we present the results of tracking the dynamic aperture with the proposed lattices.
 
 
WEP022 Status of Low Emittance Tuning at CesrTA coupling, simulation, betatron, quadrupole 1540
 
  • J.P. Shanks, M.G. Billing, R.E. Meller, M.A. Palmer, M.C. Rendina, N.T. Rider, D. L. Rubin, D. Sagan, C.R. Strohman, Y. Yanay
    CLASSE, Ithaca, New York, USA
 
  Funding: Work supported by the National Science Foundation and by the US Department of Energy under contract numbers PHY-0734867 and DE-FC02-08ER41538.
We report on the status of emittance tuning techniques at the CESR Test Accelerator CesrTA. The CesrTA experimental program requires the capability to operate in a variety of machine lattices with the smallest possible emittance. We have attempted to minimize the turn-around time of our low emittance tuning procedure. We utilize high bandwidth BPM electronics for fast, precision measurements of orbit, betatron phase, transverse coupling, and dispersion. Turn by turn data is used to measure BPM button electrode gains to a under a percent. Gain-corrected coupling data is utilized to determine BPM tilts to 10mrad, allowing for measurement of vertical dispersion at the level of 10mm. Measurement and analysis of the data for characterizing BPM response takes 5 minutes. Beam based measurement of machine functions, data analysis, and implementing corrections in the machine takes another 5 minutes. An x-ray beam size monitor provides a real time check on the effectiveness of the procedure. A typical correction results in an emittance less than 20pm at 2.1GeV in 1-2 iterations. Sub 15pm has been achieved with adjustment of closed coupling/vertical dispersion bumps and betatron tunes.
 
 
WEP024 Near-ideal Emittance Exchange at the Fermilab Photoinjector cavity, diagnostics, electron, coupling 1543
 
  • A.S. Johnson, H.T. Edwards, A.H. Lumpkin, J. Ruan, J.K. Santucci, R.M. Thurman-Keup
    Fermilab, Batavia, USA
 
  The A0 Photoinjector at Fermilab is presently home to an emittance exchange (EEX) experiment. The emittance exchange beamline consists of a 3.9 GHz normal conducting deflecting mode cavity flanked by two doglegs. Electron bunches with charges of 250 pC and energy of 14.3 MeV are routinely sent through the exchanger. Here we present results of a 1:1 transverse and longitudinal emittance exchange.  
 
WEP031 Low-Emittance Lattice Designs for ALS Ultimate Upgrade dipole, lattice, storage-ring, quadrupole 1549
 
  • C. Sun, H. Nishimura, D. Robin, C. Steier, W. Wan
    LBNL, Berkeley, California, USA
 
  Based upon the Theoretical Minimum Emittance (TME) technique, a new method has been developed to optimize low-emittance and low-beta lattices for further brightness upgrades at the Advanced Light Source (ALS). The study provides us a different perspective on the lattice design, and confirms results earlier found using both Global Scan of All Stable Settings (GLASS) and Genetic Algorithms (GA) techniques. Since the optimal low-beta lattice may have a dynamic aperture too small to allow off-axis injection, to overcome this problem, an alternating high-low beta lattice could be used for the upgrade. Several options of these high-low beta lattices are investigated using Genetic Algorithms.  
 
WEP032 Beam Transport in a Compact Dielectric Wall Accelerator for Proton Therapy proton, beam-transport, accelerating-gradient, focusing 1552
 
  • Y.-J. Chen, D.T. Blackfield, G.J. Caporaso, S.D. Nelson, B. R. Poole
    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-AC52-07NA2A27344.
To attain the highest accelerating gradient in the compact dielectric wall (DWA) accelerator, the accelerating voltage pulses should have the shortest possible duration. To do so, the DWA will be operated in the “virtual” traveling mode*. Since only a short section of HGI wall would be excited, the accelerating field’s axial profile could be non-uniform and time dependent, especially near the entrance and exit of the DWA, which could lead to dispersion in beam acceleration and transport, and eventually emittance growth. The dispersive transverse kick on a short proton bunch at the DWA entrance and its impact on acceptable input proton bunch length will be discussed. Without using any external lenses, the dispersive transverse kicks on the beam can be mitigated. Implementing the mitigations into the transport strategy, we have established a baseline transport case. Results of simulations using 3-D, EM PIC code, LSP** indicate that the DWA transport performance meets the medical specifications for intensity modulation proton treatment. Sensitivity of the transport performance to the switch timing will be presented.
* G. J. Caporaso, Y-J Chen and S. E. Sampayan, "The Dielectric Wall Accelerator", Rev. of Accelerator Science and Technology, vol. 2, p. 253 (2009).
** Alliant Techsystems Inc., http://www.lspsuite.com/.
 
 
WEP033 Using an Emittance Exchanger as a Bunch Compressor cavity, optics, coupling, simulation 1555
 
  • B.E. Carlsten, K. Bishofberger, L.D. Duffy, Q.R. Marksteiner, S.J. Russell, N.A. Yampolsky
    LANL, Los Alamos, New Mexico, USA
 
  Funding: This work is supported by the U.S. Department of Energy through the LANL/LDRD program.
An Emittance EXchanger (EEX), like a chicane, can be used for bunch compression. However, it offers a unique characteristic: the R56 term in an EEX vanishes, which decouples the final longitudinal position from the particles’ energies, thereby suppressing the microbunch instability. Also, it can provide simultaneous compression in both the longitudinal and one transverse dimensions, where, for example, the final longitudinal size is smaller than the initial horizontal size and the final horizontal size is smaller than the initial longitudinal size. In this scheme, there is no dependence on an energy slew needed for compressing the beam, simplifying the rf requirements. A bunch-compression scheme using two EEXs is presented, including CSR calculations.
 
 
WEP036 Start-to-End Beam Dynamics Simulations for the SRF Accelerator Test Facility at Fermilab simulation, quadrupole, cavity, focusing 1561
 
  • C.R. Prokop, P. Piot
    Northern Illinois University, DeKalb, Illinois, USA
  • M.D. Church, Y.-E. Sun
    Fermilab, Batavia, USA
 
  Funding: LANL Laboratory Directed Research and Development program 20110067DR. U.S. DoE contract No. DE-FG02-08ER41532 Northern Illinois University. Fermi Research Alliance, LLC Contract No. DE-AC02-07CH11359.
Fermilab is currently building a superconducting RF (SCRF) linear-accelerator test facility. In addition to testing ILC-spec SCRF accelerating modules for ILC and Project-X, the facility will be capable of supporting a variety of advanced accelerator R&D experiments. The accelerator facility includes a 40-MeV photoinjector capable of producing bunches with variable parameters. In this paper, we present start-to-end simulations of the accelerator beamline.
 
 
WEP042 FACET Emittance Growth simulation, plasma, wakefield, acceleration 1573
 
  • J.T. Frederico, M.J. Hogan, M.D. Litos, Y. Nosochkov, T.O. Raubenheimer
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by the U.S. Department of Energy under contract number DE-AC02-76SF00515.
FACET, the Facility for Advanced Accelerator and Experimental Tests, is a new facility being constructed in sector 20 of the SLAC linac primarily to study beam driven plasma wakefield acceleration. The FACET beamline consists of a chicane and final focus system to compress the 23 GeV, 3 nC electron bunches to ~20μm long and ~10μm wide. Simulations of the FACET beamline indicate the short-duration and large, 1.5% rms energy spread beams may suffer a factor of four emittance growth from a combination of chromaticity, incoherent synchrotron radiation (ISR), and coherent synchrotron radiation (CSR). Emittance growth is directly correlated to head erosion in plasma wakefield acceleration and is a limiting factor in single stage performance. Studies of the geometric, CSR, and ISR components are presented. Numerical calculation of the rms emittance can be overwhelmed by long tails in the simulated phase space distributions; more useful definitions of emittance are given. A complete simulation of the beamline is presented as well, which agrees with design specifications.
 
 
WEP044 Emittance and Phase Space Exchange cavity, quadrupole, lattice, optics 1576
 
  • D. Xiang, A. Chao
    SLAC, Menlo Park, California, USA
 
  Funding: This work was supported by the US DOE under Contract No. DE-AC02-76SF00515.
Alternative chicane-type beamlines are proposed for exact emittance exchange between horizontal phase space (x,x') and longitudinal phase space (z, delta). Methods to achieve exact phase space exchanges, i.e. mapping x to z, x' to delta, z to x and delta to x' are suggested. Some applications of the phase space exchanger and the feasibility of an emittance exchange experiment with the proposed beamline at SLAC are discussed.
 
 
WEP067 Cornell ERL Tolerance Simulations lattice, undulator, simulation, quadrupole 1603
 
  • C.E. Mayes
    CLASSE, Ithaca, New York, USA
 
  Funding: Supported by NSF award DMR-0807731
Cornell University is planning to build an Energy Recovery Linac (ERL) hard x-ray lightsource operating at 5 GeV. Simulations of its approximately 3 km of electron beamline that incorporate a host of reasonable alignment and field errors, and their compensation by an orbit correction scheme, are presented. These simulations start with realistic particle distributions just after injection and track them through acceleration, the production of undulator radiation, deceleration (energy recovery), and finally transport to the beam stop. To this realistic model, single error sources are further added with increasing magnitudes in order to establish alignment and field tolerance estimates.
 
 
WEP072 Control of Chaotic Particle Motion Using Adiabatic Thermal Beams focusing, resonance, plasma, quadrupole 1609
 
  • H. Wei, C. Chen
    MIT, Cambridge, Massachusetts, USA
 
  Funding: This work was supported by US Department of Energy, Grant No. DE-FG02-95ER40919 and Grant No. DE-FG02-05ER54835.
Charged-particle motion is studied in the self-electric and self-magnetic fields of a well-matched, intense charged-particle beam and an applied periodic solenoidal magnetic focusing field. The beam is assumed to be in a state of adiabatic thermal equilibrium. The phase space is analyzed and compared with that of the well-known Kapchinskij-Vladimirskij (KV)-type beam equilibrium. It is found that the widths of nonlinear resonances in the adiabatic thermal beam equilibrium are narrower than those in the KV-type beam equilibrium. Numerical evidence is presented, indicating almost complete elimination of chaotic particle motion in the adiabatic thermal beam equilibrium.
 
 
WEP073 Adiabatic Thermal Beam Equilibrium in Periodic Focusing Fields focusing, quadrupole, lattice, plasma 1612
 
  • C. Chen
    MIT, Cambridge, Massachusetts, USA
 
  Funding: This work was supported by US Department of Energy, Grant No. DE-FG02-95ER40919 and Grant No. DE-FG02-05ER54835.
Adiabatic thermal equilibrium is an important state of a charged-particle beam. The rigid-rotor thermal beam equilibrium in a uniform magnetic focusing field is established. The equivalent kinetic and warm-fluid theories of adiabatic thermal beam equilibrium in a periodic solenoidal magnetic focusing field are discussed. Good agreement between theories and experiment is found. The warm-fluid theory of adiabatic thermal beam equilibrium in an alternating-gradient quadrupole magnetic focusing field is discussed. For the periodic solenoidal magnetic focusing field, charged-particle dynamics in the adiabatic thermal beam equilibrium are studied numerically and compared with those in the Kapchinskij-Vladimirskij (KV) type beam equilibrium. Numerical evidence is presented, indicating almost complete elimination of chaotic particle motion in the adiabatic thermal beam equilibrium.
 
 
WEP082 Crab Crossing Consideration for MEIC cavity, electron, proton, betatron 1627
 
  • S. Ahmed, Y.S. Derbenev, G.A. Krafft, Y. Zhang
    JLAB, Newport News, Virginia, USA
  • A. Castilla, J.R. Delayen, S.D. Silva
    ODU, Norfolk, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
Crab crossing of colliding electron and ion beams is essential for accommodating the ultra high bunch repetition frequency in the conceptual design of MEIC – a high luminosity polarized electron-ion collider at Jefferson Lab. The scheme eliminates parasitic beam-beam interactions and avoids luminosity reduction by restoring head-on collisions at interaction points. In this paper, we report simulation studies of beam dynamics with crab cavities for MEIC design. The detailed study involves full 3-D simulations of particle tracking through the various configurations of crab cavities for evaluating the performance. To gain insight, beam and RF dominated fields with other parametric studies will be presented in the paper.
 
 
WEP090 Simulation Study of Intrabeam Scattering in Low Emittance Ring scattering, simulation, lattice, storage-ring 1639
 
  • W. Fan, G. Feng, D.H. He, W. Li, L. Wang, S.C. Zhang, T. Zhou
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  HALS(Hefei Advanced Light Source) is under designing dedicated to good coherence and high brightness at 1.5GeV. Low emittance is required to reach the design request. Due to the low energy and emittance with relative high bunch charge, intrabeam scattering effect will be very strong. It is worth accurately calculating to check if the design goal can be reached. Theoretic calculation based on Gaussian beam distribution doesn't warrant in strong IBS regime. In this paper we present the results of particle simulation study of intrabeam scattering effect on a temporary design lattice of HALS ring.  
 
WEP094 Space Charge Measurements with a High Intensity Bunch at the Fermilab Main Injector proton, simulation, space-charge, injection 1648
 
  • K. Seiya, B. Chase, J.E. Dey, P.W. Joireman, I. Kourbanis
    Fermilab, Batavia, USA
  • A. Yagodnitsyna
    NSU, Novosibirsk, Russia
 
  Fermilab Main Injector will be required to operate with 3 times higher bunch intensity than today for Project X. The plan to study the space charge effects at the injection energy with intense bunches will be discussed.  
 
WEP096 Simulations of Space Charge in the Fermilab Main Injector space-charge, simulation, proton, lattice 1654
 
  • E.G. Stern, J.F. Amundson, P. Spentzouris
    Fermilab, Batavia, USA
  • J. Qiang, R.D. Ryne
    LBNL, Berkeley, California, USA
 
  The Fermilab Project X plan for future high intensity running relies on the Main Injector as the engine for delivering protons in the 60-120 GeV energy range. Project X plans call for increasing the number of protons per Main Injector bunch from the current value of 1.0× 1011 to 3.0× 1011. Space charge effects at the injection energy of 8 GeV have the potential to seriously disrupt operations. We report on ongoing simulations with Synergia, our multi-physics process accelerator modeling framework, to model space charge effects in the Main Injector combined with the effects of magnet fringe fields and apertures.  
 
WEP101 Smooth Approximation of Dispersion with Strong Space Charge space-charge, beam-transport, heavy-ion, focusing 1665
 
  • S. Bernal, B.L. Beaudoin, T.W. Koeth, P.G. O'Shea
    UMD, College Park, Maryland, USA
 
  Funding: This work is funded by the US Dept. of Energy Offices of High Energy Physics and High Energy Density Physics, and by the US Dept. of Defense Office of Naval Research and Joint Technology Office.
We apply the Venturini-Reiser envelope-dispersion equations* to a continuous beam in a uniform focusing/bending lattice to study the combined effects of linear dispersion and space charge. Within this simple model we investigate the scaling of average dispersion and the effects on beam dimensions; we also introduce a generalization of the space-charge intensity parameter and apply it to the University of Maryland Electron Ring (UMER) and other machines. In addition, we present results of calculations to test the smooth approximation by solving the Venturini-Reiser original equations and also through simulations with the code ELEGANT.
*M. Venturini and M. Reiser, Phys. Rev. Lett. 81, 1, p. 96, 6 July 1998
 
 
WEP103 Ion Instability Study for the ILC 3 km Damping Ring ion, damping, simulation, vacuum 1671
 
  • G.X. Xia
    MPI-P, München, Germany
 
  The ILC GDE is currently pushing the cost reduction for all subsystems of the ILC project for the Technique Design Phase 1. A short damping ring with circumference of 3.2 km was developed for this purpose. Based on this lattice, we performed a weak-strong simulation study of the ion instability in the electron damping ring for various beam parameters and vacuum pressures. The simulation results are given in this paper.  
 
WEP109 Simulations of Electron Cloud Induced Instabilities and Emittance Growth for CesrTA simulation, electron, positron, synchrotron 1683
 
  • K.G. Sonnad, K.R. Butler
    Cornell University, Ithaca, New York, USA
  • G. Dugan, M.A. Palmer
    CLASSE, Ithaca, New York, USA
  • M.T.F. Pivi
    SLAC, Menlo Park, California, USA
 
  Funding: US Department of Energy DE-FC02-08ER41538, National Science Foundation PHY-0734867
We present results of a series of studies obtained using the simulation code CMAD to study how electron clouds affect the dynamics of positron beams in CesrTA. The study complements ongoing experiments dedicated for studying the same phenomena. The simulation involves tracking positrons through the CesrTA lattice and simultaneously computing the force exerted due to space charge of the electrons on each of the tracked positrons. The electrons themselves are allowed to evolve under the influence of the positrons. Several results bear a close resemblance to what has been observed experimentally.
 
 
WEP114 Transverse Instability of the Antiproton Beam In the Recycler Ring antiproton, extraction, damping, bunching 1698
 
  • L.R. Prost, C.M. Bhat, A.V. Burov, J.L. Crisp, N. Eddy, M. Hu, A.V. Shemyakin
    Fermilab, Batavia, USA
 
  Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy.
The brightness of the antiproton beam in Fermilab’s 8 GeV Recycler ring is limited by a transverse instability. This instability has occurred during the extraction process to the Tevatron for large stacks of antiprotons even with dampers in operation. This paper describes observed features of the instability, introduces the threshold phase density to characterize the beam stability, and finds the results to be in agreement with a resistive wall instability model. Effective exclusion of the longitudinal tails from Landau damping by decreasing the depth of the RF potential well is observed to lower the threshold density by up to a factor of two.
 
 
WEP136 Modelling of the EMMA ns-FFAG Ring Using GPT space-charge, injection, quadrupole, electron 1734
 
  • R.T.P. D'Arcy
    UCL, London, United Kingdom
  • J.K. Jones, B.D. Muratori
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  EMMA (Electron Machine with Many Applications) is a prototype non-scaling Fixed-Field Alternating Gradient (ns-FFAG) accelerator whose construction at Daresbury Laboratory, UK, was completed in Aug 2010. The energy recovery linac ALICE will serve as an injector for EMMA, within an energy range of 10-20 MeV. The injection line consists of a dogleg to extract the beam from ALICE, a matching section, and tomography section for transverse emittance measurements. This is followed by a transport section to the injection point of the EMMA ring. The ring is composed of forty two cells, each containing one focusing and one defocusing quadrupole. Commissioning of the EMMA ring started in late 2010. A number of different injection energy and bunch charge regimes are planned; for some of the regimes the effects of space charge may be significant. It is therefore necessary to model the electron beam transport in the injection line and the ring using a code capable of both calculating the effect of and compensating for space charge. Therefore the General Particle Tracer (GPT) code has been used. A range of injection beam parameters have been modelled for comparison with experimental results.  
 
WEP139 Comparison of 1D and 2D CSR Models with Application to the Fermi@Elettra Bunch Compressors dipole, electron, synchrotron, synchrotron-radiation 1743
 
  • G. Bassi
    BNL, Upton, New York, USA
  • J.A. Ellison, K.A. Heinemann
    UNM, Albuquerque, New Mexico, USA
 
  Funding: Work partially supported by DOE grant DE-FG02-99ER41104
We compare our 2D mean field (Vlasov-Maxwell) treatment of coherent synchrotron radiation (CSR) effects with 1D approximations of the CSR force which are commonly implemented in CSR codes. In our model we track particles in 4D phase space and calculate 2D forces*. The major cost in our calculation is the computation of the 2D force. To speed up the computation and improve 1D models we also investigate approximations to our exact 2D force. Preliminary results are encouraging**. As an application, we present numerical results for the LCLS bunch compressors, where recently detailed measurements of the CSR-induced energy loss and transverse emittance growth have been performed and compared with numerical calculations***.
* Phys. Rev. ST Accel. Beams 12, 080704 (2009)
** http://www.lnf.infn.it/conference/uBI10/
*** Phys. Rev. ST Accel. Beams 12, 030704 (2009)
 
 
WEP140 Benchmarking Stepwise Ray-Tracing in Rings in Presence of Radiation Damping damping, radiation, lattice, synchrotron 1746
 
  • F. Méot
    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.
A number of recent machine designs, including ‘‘nano-beams'', sub-millimeter ‘‘low-beta'' IRs, etc., require high accuracy on beam orbit and beam size, reliable evaluation of machine parameters, dynamic apertures, etc. This can only be achieved using high precision simulation tools. Stepwise ray-tracing methods are in this category of tools, stochastic synchrotron radiation and its effects on an electron beam in a storage ring are simulated here in that manner. Benchmarking of the method against analytical model expectations, using a Chasman-Green cell, is presented.
 
 
WEP154 Direct Numerical Modeling of E-Cloud Driven Instability of a Bunch Train in the CERN SPS electron, simulation, feedback, proton 1776
 
  • J.-L. Vay, M.A. Furman, M. Venturini
    LBNL, Berkeley, California, USA
 
  Funding: Supported by the US-DOE under Contract DE-AC02-05CH11231, the SciDAC program ComPASS and the US-LHC Accelerator Research Program (LARP). Used resources of NERSC and the Lawrencium cluster at LBNL.
Electron clouds impose limitations on current accelerators that may be more severe for future machines, unless adequate measures of mitigation are taken. It has been proposed recently to use feedback systems operating in the GHz range to damp single-bunch transverse coherent electron cloud driven instabilities that may occur in relatively long, ns scale, proton bunches such as those in the CERN SPS. The simulation package WARP-POSINST was recently upgraded for handling multiple bunches and modeling concurrently the electron cloud buildup and its effect on the beam, allowing for direct self-consistent simulation of bunch trains generating, and interacting with, electron clouds. We have used the WARP-POSINST package on massively parallel supercomputers to study the growth rate and frequency patterns in space-time of the electron cloud driven transverse instability for a proton bunch train in the CERN SPS accelerator with, or without, feedback models (with various levels of idealization) for damping the instability. We will present our latest simulation results, contrast them with actual measurements and discuss the implications for the design of the actual feedback system.
 
 
WEP160 Inclusion of Surface Roughness Effects in Emission Modeling With the MICHELLE Code cathode, electron, space-charge, brightness 1788
 
  • J.F. DeFord
    STAAR/AWR Corporation, Mequon, USA
  • N.J. Dionne, S.G. Ovtchinnikov, J.J. Petillo
    SAIC, Burlington, Massachusetts, USA
 
  High-brightness electron beams are needed in millimeter-wave tubes and other high-power RF applications. Cathode surface roughness at the micron scale, commonly due to machining or other effects, can lead to broadening of the velocity distribution of electrons downstream, increasing emittance and lowering beam brightness. In this paper we investigate methods of including surface roughness effects in the MICHELLE code*. Modeling of typical surface imperfections over an entire cathode is not feasible, since it requires representation of features that are 3 to 5 orders of magnitude smaller than the cathode. Moreover, the actual surface imperfections for a given cathode are unknown without a prohibitive microscopic investigation of the surface, and these details vary between cathodes with the same machining history. To avoid these problems we investigated modifications to emission models that can account for these effects in an average sense, allowing the use of a smooth emission surface in a model while retaining the essential effects of the rough surface on the beam. We present the results of this investigation, along with representative solutions for sample structures.
*John Petillo, et al., “Recent Developments in the MICHELLE 2D/3D Electron Gun and Collector Modeling Code”, IEEE Trans. Electron Devices Sci., vol. 52, no. 5, May 2005, pp. 742-748.
 
 
WEP206 An Accumulator/Pre-Booster for the Medium-Energy Electron Ion Collider at JLab booster, ion, injection, proton 1873
 
  • B. Erdelyi, S. Abeyratne
    Northern Illinois University, DeKalb, Illinois, USA
  • Y.S. Derbenev, G.A. Krafft, Y. Zhang
    JLAB, Newport News, Virginia, USA
  • S.L. Manikonda, P.N. Ostroumov
    ANL, Argonne, USA
 
  Future nuclear physics facilities such as the proposed electron ion collider (MEIC) will need to achieve record high luminosities in order to maximize discovery potential. Among the necessary ingredients is the ability to generate, accumulate, accelerate, and store high current ion beams from protons to lead ions. One of the main components of this ion accelerator complex for MEIC chain is the accumulator that also doubles as a pre-booster, which takes 200 MeV protons from a superconducting linear accelerator, accumulates on the order of 1A beam, and boosts its energy to 3GeV, before extraction to the next accelerator in the chain, the large booster. This paper describes its design concepts, and summarizes some preliminary results, including linear optics, space charge dynamics, and spin polarization resonance analysis.  
 
WEP210 Low Energy Beam Measurements Using PHIL Accelerator at LAL, Comparison with PARMELA Simulations solenoid, simulation, laser, gun 1885
 
  • J. Brossard, F. Blot, C. Bruni, S. Cavalier, J-N. Cayla, A. Gonnin, M. Joré, P. Lepercq, S.B. Letourneur, B.M. Mercier, H. Monard, C. Prevost, R. Roux, A. Variola
    LAL, Orsay, France
 
  PHIL (“PHoto-Injector at LAL") is a new electron beam accelerator at LAL. This accelerator is dedicated to test and characterize electron RF-guns and to deliver electron beam to users. This machine has been designed to produce and characterise low energy (E<10 MeV), small emittance (e<10 p.mm.mrad), high brilliance electrons bunch at low repetition frequency (n<10Hz). The first beam has been obtained on the 4th of November 2009. The current RF-gun tested on PHIL is the AlphaX gun, a 2.5 cell S-band cavity designed by LAL for the plasma accelerator studies performed at the Strathclyde university. This paper will present the first AlphaX RF-gun characterizations performed at LAL on PHIL accelerator, and will show comparisons between measurements and PARMELA simulations.  
 
WEP213 New Development of a RFQ Beam Matching Section rfq, ion-source, ion, linac 1891
 
  • M. Baschke, N. Müller, A. Schempp, J.S. Schmidt
    IAP, Frankfurt am Main, Germany
 
  Funding: BMBF
Funneling is a method to increase low energy beam currents in multiple stages. The Frankfurt Funneling Experiment is a model of such a stage. The experiment is built up of two ion sources with electrostatic lens systems, a Two-Beam-RFQ accelerator, a funneling deflector and a beam diagnostic system. The two beams are bunched and accelerated in a Two-Beam RFQ. A funneling deflector combines the bunches to a common beam axis. Current work is the construction and beam tests of a new beam transport system between RFQ accelerator and deflector. With extended RFQ-electrodes the drift between the Two-Beam-RFQ and the rf-deflector will be minimized and therefore unwanted emittance growth reduced. First rf-measurements with the improved Two-Beam-RFQ will be presented.
 
 
WEP222 Low Energy Beam Diagnostic for APEX, the LBNL VHF Photo-injector diagnostics, gun, electron, cathode 1903
 
  • D. Filippetto, J.M. Byrd, M.J. Chin, C.W. Cork, S. De Santis, L.R. Doolittle, J. Feng, W.E. Norum, C. F. Papadopoulos, G.J. Portmann, D.G. Quintas, F. Sannibale, M.E. Stuart, R.P. Wells, M.S. Zolotorev
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231
A high-repetition rate (MHz-class), high-brightness electron beam photo-gun is under construction at Lawrence Berkeley National Laboratory in the framework of the Advanced Photo-injector EXperiment (APEX). The injector gun is based on a normal conducting 187 MHz RF cavity operating in CW mode. In its first operational phase it will deliver short bunches (~ 1 to tens of picoseconds) with energy of 750keV, and bunch charges ranging from 1pC to 1nC. Different high efficiency cathode materials will be tested, and the beam quality will be studied as a function of parameters as charge, initial bunch length and transverse size, focusing strength. Both the laser and electron beam diagnostics have been designed to assure the needed flexibility. In particular a high-resolution electron diagnostic section after the photo-gun provides the necessary dynamical range for scanned beam parameters: energy and energy spread, charge and current, transverse and longitudinal phase spaces, slice properties. The photo-gun electron beam diagnostic layout is presented, and the hardware choices, resolution and achievable dynamical ranges are also discussed.
 
 
WEP226 Commissioning Results of the ReA RFQ at MSU* rfq, ion, cryomodule, acceleration 1912
 
  • D. Leitner, C. Benatti, S.W. Krause, D. Morris, S. Nash, J. Ottarson, G. Perdikakis, M. Portillo, R. Rencsok, T. Ropponen, L. Tobos, N.R. Usher, D. Wang
    NSCL, East Lansing, Michigan, USA
  • J. Haeuser
    Kress GmbH, Biebergemuend, Germany
  • O.K. Kester
    GSI, Darmstadt, Germany
  • F. Marti, E. Tanke, X. Wu, Q. Zhao
    FRIB, East Lansing, Michigan, USA
  • A. Schempp, J.S. Schmidt, H. Zimmermann
    IAP, Frankfurt am Main, Germany
 
  Funding: Project funded by Michigan State University
The Facility for Rare Isotope Beams (FRIB) is currently in the preliminary design phase at Michigan State University (MSU). FRIB consists of a driver LINAC for the acceleration of heavy ion beams, followed by a fragmentation target station and a ReAccelerator facility (ReA3). ReA3 comprises gas stopper systems, an Electron Beam Ion Trap (EBIT) charge state booster, a room temperature radio frequency quadrupole (RFQ), a LINAC using superconducting quarter wave resonators and an achromatic beam transport and distribution line to the new experimental area. Beams from ReA3 will range from 3 MeV/u for heavy ions to about 6 MeV/u for light ions. The ReA3 RFQ, which is of the 4 rod type, is designed to accelerate ions with an Q/A of 0.2 to 0.5 from 12 keV/u to 600 keV/u. The RFQ operates at a frequency of 80.5 MHz and power levels up to 120 kW at 10% duty factor. In this paper we will report on commissioning results from the ReA3 RFQ using a H2+ and He+ beam from an auxiliary ion source.
 
 
WEP231 TRIUMF Cyclotron Beam Quality Improvement cyclotron, extraction, TRIUMF, beam-losses 1921
 
  • I.V. Bylinskii, R.A. Baartman, F.W. Bach, J.F. Cessford, G. Dutto, Y.-N. Rao, L.W. Root, R. Ruegg
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
 
  TRIUMF cyclotron for decades operated at 500 MeV. Recently, the two primary beamlines 1A and 2A, have been reconfigured for running at 480 MeV. The objective was to reduce beam losses caused by the electromagnetic stripping by 30%. The radiation losses reduction was confirmed with both online measurements and residual activation field mapping after 8 month of beam production. In order to improve stability of both primary beams, one of the harmonic coils was configured in Bz-mode to compensate for the beam split ratio fluctuations. Br-mode of this coil and two outer radius trim coils was utilized to correct the beam vertical position at extraction. Moreover, to make the beam spot position on the target stable and insensitive to any uncontrolled movement of the stripper foil due to heat distortion, the beamline front end optics was tuned to compensate the cyclotron's inherent dispersion. Details of these developments and improvements are discussed in the paper.  
 
WEP245 Optimization of DC Photogun Electrode Geometry cathode, focusing, gun, solenoid 1945
 
  • J.M. Maxson
    Cornell University, Ithaca, New York, USA
  • I.V. Bazarov, B.M. Dunham, K.W. Smolenski
    CLASSE, Ithaca, New York, USA
 
  DC photoguns that employ electrostatic focusing to obtain lower beam emittance must inherently trade off between focusing strength and the field at the photocathode, and are traditionally pushed to the limits of breakdown voltage. In this paper, we numerically investigate a highly parametrized electrostatic geometry exploring the trade-off between the voltage breakdown condition and electrostatic focusing. We then compare the results to DC gun designs where the focusing is introduced via embedded solenoidal fields. Finally, we present investigations for a multi-anode gun design that seeks to simultaneously achieve both high electric field at the photocathode and high gun voltage without violating the empirical voltage breakdown condition. In the most feasible cases, the electrode geometry is optimized via genetic algorithms. Designs on the optimal front are compared with the current performance of the Cornell ERL prototype DC photogun.  
 
WEP263 A Multiple Cathode Gun Design for the eRHIC Polarized Electron Source cathode, cavity, gun, electron 1969
 
  • X. Chang, I. Ben-Zvi, J. Kewisch, V. Litvinenko, A.I. Pikin, V. Ptitsyn, T. Rao, B. Sheehy, J. Skaritka, Q. Wu
    BNL, Upton, Long Island, New York, USA
  • E. Wang
    PKU/IHIP, Beijing, People's Republic of China
  • T. Xin
    Stony Brook University, Stony Brook, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The future electron-ion collider eRHIC requires a high average current (~50 mA), short bunch (~3 mm), low emittance (~20 μm) polarized electron source. The maximum average current of a polarized electron source so far is more than 1 mA, but much less than 50 mA, from a GaAs:Cs cathode [1]. One possible approach to overcome the average current limit and to achieve the required 50 mA beam for eRHIC, is to combine beamlets from multiple cathodes to one beam. In this paper, we present the feasibility studies of this technique.
 
 
WEP268 Changes in LEBT/MEBT at the BNL 200 MeV Linac linac, polarization, solenoid, rfq 1978
 
  • D. Raparia, J.G. Alessi, J.M. Fite, O. Gould, V. LoDestro, M. Okamura, J. Ritter, A. Zelenski
    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.
After reconfiguration of the low energy (35 keV) and the medium energy (750 keV) transport lines in 2009-10, the Brookhaven linac is now delivering the highest intensity beam since it was built in 1970 (~120 μA average current of H to the Brookhaven Linac Isotope Producer). It is also now delivering lower emittance polarized H ion beam for the polarized program at RHIC. To increase the intensity further, we are replacing the buncher in the 750 keV line with one with higher Q value, to allow operation at higher power. Also, to improve polarization, we are replacing the magnetic solenoid before the RFQ in the 35 keV line by a solenoid-einzel lens combination. The paper will report on the results of these changes.
 
 
WEP279 Improvements on the Design of an Ultra-Low Emittance Injector for a Future X-ray FEL Oscillator cathode, gun, electron, cavity 2002
 
  • X.W. Dong, K.-J. Kim
    ANL, Argonne, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DEAC02-06CH11357.
The concept of an ultra-low transverse emittance injector for the X-ray Free-Electron Laser Oscillator* was discussed at PAC09**. Two problems come to mind. A dual-frequency rf chopper for reducing the beam rate from 100 MHz to 1 ~ 3 MHz would limit our choice of the beam repetition rate. The electron back-bombardment could be solved by embedding a three-pole wiggler*** in the nose cone of the gun cavity, but that results in increased emittance. Inspired by the concept of a triode gun, the injector now includes a gated 100 MHz rf gun with thermionic cathode to avoid those limitations. The design has been studied and is capable of producing 40 pC bunches with 0.1 micrometer effective transverse rms emittance.
* K.-J. Kim et al., Phys. Rev. Lett. 100, 244802 (2008).
** P.N. Ostroumov et al., Proc. of PAC09, p.461 (2009).
*** M. Borland et al., Proc. of LINAC10, to be published.
 
 
WEP280 Development of an Ultra-Low-Emittance RF PhotoInjector for a Future X-Ray FEL Oscillator laser, cavity, gun, space-charge 2005
 
  • X.W. Dong, K.-J. Kim, N. Sereno, C.-X. Wang, A. Zholents
    ANL, Argonne, USA
 
  Funding: Work supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DEAC02-06CH11357.
The proposed x-ray free-electron laser oscillator* requires continuous electron bunches with ultra-low normalized transverse emittance of less than 0.1 micrometer, a bunch charge of 40 pC, an rms uncorrelated energy spread of less than 1.4 MeV, produced at a rate between 1 MHz to 10 MHz. The bunches are to be compressed to an rms length of ~1 ps and accelerated to the final energy of 7 GeV. In this paper, we discuss a design for an ultra-low-emittance injector based on a 325-MHz room-temperature rf cavity and a Cs2Te photocathode. The results of initial optimizations of the beam dynamics with a focus on extracting and preserving ultra-low emittance will be presented.
* K.-J. Kim et al., Phys. Rev. Lett. 100, 244802 (2008).
 
 
WEP282 Design of the NSLS-II Linac Front End Test Stand linac, gun, solenoid, bunching 2011
 
  • R.P. Fliller, M.P. Johanson, M. Lucas, J. Rose, T.V. Shaftan
    BNL, Upton, Long Island, New York, USA
 
  Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The NSLS-II operational parameters place very stringent requirements on the injection system. Among these are the charge per bunch train at low emittance that is required from the linac along with the uniformity of the charge per bunch along the train. The NSLS-II linac is a 200 MeV linac produced by RI Research Instruments GmbH. Part of the strategy for understanding to operation of the injectors is to test the front end of the linac prior to its installation in the facility. The linac front end consists of a 90 keV electron gun, 500 MHz subharmonic prebuncher, focusing solenoids and a suite of diagnostics. The diagnostics in the front end need to be supplemented with an additional suite of diagnostics to fully characterize the beam. In this paper we discuss the design of a test stand to measure the various properties of the beam generated from this section. In particular, the test stand will measure the charge, transverse emittance, energy, energy spread, and bunching performance of the linac front end under all operating conditions of the front end.
 
 
WEP283 Simulations of Transverse Stacking in the NSLS-II Booster booster, linac, simulation, lattice 2014
 
  • R.P. Fliller, T.V. Shaftan
    BNL, Upton, Long Island, New York, USA
 
  Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The NSLS-II injection system consists of a 200 MeV linac and a 3 GeV booster. The linac needs to deliver 15 nC in 80 - 150 bunches to the booster every minute to achieve current stability goals in the storage ring. This is a very stringent requirement that has not been demonstrated at an operating light source. We have developed a scheme to transversely stack two bunch trains in the NSLS-II booster in order to alleviate the charge requirements on the linac. This scheme has been outlined previously. In this paper we show particle tracking simulations of the tracking scheme. We show that the booster lattice has sufficient orbit correction and dynamic aperture at injection to maintain the charge and emittance of the first beam while it circulates waiting for the next train to arrive. We also show simulations of the booster ramp with a stacked beam for a variety of lattice errors and injected beam parameters. In all cases the performance of the proposed stacking method is sufficient to reduce the required charge from the linac. For this reason the injection system of the NSLS-II booster is being designed to include this feature.
 
 
WEP289 The Impact of Laser Polarization in Multiphoton Photoemission from a Copper Cathode laser, cathode, polarization, electron 2026
 
  • R.K. Li, J.T. Moody, P. Musumeci, C.M. Scoby, H.L. To, M.T. Westfall
    UCLA, Los Angeles, California, USA
 
  Multiphoton photoemission from a copper cathode has been recently demonstrated to be a simple and efficient method to generate high quality electron beams. To further improve this scheme to achieve higher charge yielding efficiency and lower intrinsic emittance, we explored the effects of laser polarization at oblique incidence. Charge yields of s and p polarization from coated and uncoated cathodes were measured. The vectorial photoelectric effect was observed on the uncoated cathode but much less evident on the coated one, suggesting that surface properties are critical to the vectorial effect and in general important in photoemission. The results not only are useful in the optimization of an rf photoinjector, but also allow deeper understanding of the photoemission physics.
* P. Musumeci et al., Phys. Rev. Lett. ZeHn4, 084801 (2010).
** P. Musumeci et al., Phys. Rev. Lett. ZeHn0, 244801 (2008).
 
 
WEP290 A Novel Electron Gun for Off-axis Beam Injection gun, electron, cathode, linac 2029
 
  • Yu.A. Kubyshin
    UPC, Barcelona, Spain
  • A.V. Aloev, N.I. Pakhomov, V.I. Shvedunov
    MSU, Moscow, Russia
 
  For certain type of electron accelerators injection from an off-axis cathode is required. This is the case of a race-track microtron (RTM), in which the beam passes several times through the accelerating structure, or of a high power standing wave electron linac, for which the lifetime of an on-axis cathode would be strongly reduced by the electron back-bombardment. The standard solution with the beam injection via a dipole magnet from an electron gun placed off-axis is too bulky, moreover in case of RTMs it requires special compensating dipoles. An annular ring cathode gun used in some accelerators leads to large beam emittance and divergence. As a new solution we describe a 3D on-axis electron gun with an off-axis cathode and a central hole for the beam passage. Results of the design optimization and performance of an electron gun built for a miniature 12 MeV RTM for medical applications are presented. We also discuss results of the beam parameters measurements and estimates of the beam emittance.  
 
THOAS1 On the Importance of Symmetrizing RF Coupler Fields for Low Emittance Beams gun, quadrupole, dipole, coupling 2044
 
  • Z. Li, C. Adolphsen, A.E. Vlieks, F. Zhou
    SLAC, Menlo Park, California, USA
 
  Funding: Work was supported by DOE Contract No. DE-AC02-76SF00515 and used computing resources at NERSC supported by DOE Contract No. DE-AC02- 05CH11231.
The input power of accelerator structure is normally fed through a coupling slot(s) on the outer wall of the accelerator structure via magnetic coupling. While providing perfect matching, the coupling slots may produce non-axial-symmetric fields in the coupler cell that can induce emittance growth as the beam is accelerated in such a field. This effect is especially important for low emittance beams at low energies such as in the injector accelerators for light sources. In this paper, we present studies of multipole fields of different rf coupler designs and their effect on beam emittance for an X-band photocathode gun, being jointly designed with LLNL, and the X-band accelerator structures. We will present symmetrized rf coupler designs for these components to preserve the beam emittance.
 
slides icon Slides THOAS1 [1.512 MB]  
 
THOAS4 Enhancement of RF Breakdown Threshold of Microwave Cavities by Magnetic Insulation cavity, electron, lattice, collider 2053
 
  • D. Stratakis
    UCLA, Los Angeles, California, USA
  • J.C. Gallardo, R. B. Palmer
    BNL, Upton, Long Island, New York, USA
 
  Funding: This work is funded by US Dept. of Energy grant number DE AC02-98CH10886.
Limitations on the maximum achievable accelerating gradient of microwave cavities can influence the performance, length, and cost of particle accelerators. Gradient limitations are widely believed to be initiated by electron emission from the cavity surfaces. Here, we show that field emission is effectively suppressed by applying a tangential magnetic field to the cavity walls, so higher gradients can be achieved. Numerical simulations indicate that the magnetic field prevents electrons leaving these surfaces and subsequently picking up energy from the electric field. Implementation of the proposed concept into prospective particle accelerator applications is studied by two specific examples - a multi TeV lepton-antilepton collider and a linear muon accelerator driver for an intense neutrino source.
 
slides icon Slides THOAS4 [1.441 MB]  
 
THOBN2 Muon Collider Final Cooling in 30-50 T Solenoids solenoid, acceleration, simulation, induction 2061
 
  • R. B. Palmer, R.C. Fernow
    BNL, Upton, Long Island, New York, USA
  • J.L. Lederman
    UCLA, Los Angeles, California, USA
 
  Muon ionization cooling to the required transverse emittance of 25 microns can be achieved with liquid hydrogen in high field solenoids, provided that the momenta are low enough. At low momenta, the longitudinal emittance rises because of the negative slope of energy loss versus energy. Assuming initial emittances that have been achieved in six dimensional cooling simulations, optimized designs are given using solenoid fields limited to 30, 40, and 50 T. The required final emittances are achieved for the two higher field cases.  
slides icon Slides THOBN2 [0.319 MB]  
 
THOBS2 Optimization of Magnet Stability and Alignment for NSLS-II alignment, storage-ring, damping, ion 2082
 
  • S.K. Sharma, L. Doom, A.K. Jain, P.N. Joshi, F. Lincoln, V. Ravindranath
    BNL, Upton, Long Island, New York, USA
 
  Funding: This work was supported by Department of Energy contract DE-AC02-98CH10886
The high-brightness design of NSLS-II requires uncorrelated vertical RMS motion of the multipole magnets on a girder to be less than 25 nm. Also, the highly nonlinear lattice requires alignment of the multipole magnets to 30 microns. The speaker will describe the stability of the girder-magnets assembly and the factors affecting it, such as ambient ground motion and temperature fluctuations in the storage ring. Technical solutions to achieve the desired stability will be presented as well.
 
slides icon Slides THOBS2 [4.431 MB]  
 
THOCN1 Cathodes for Photoemission Guns electron, laser, gun, vacuum 2099
 
  • L. Cultrera
    CLASSE, Ithaca, New York, USA
 
  The last decade has seen a considerable interest in pursuit and realization of novel light sources such as Free Electron Lasers and Energy Recovery Linacs that promise to deliver unprecedented quality x-ray beams. The performance of these machines is strongly related to the brightness of the electron beam generating the x-rays. The brightness of the electron beam itself is mainly limited by the physical processes by which electrons are generated. For laser based photoemission sources this limit is ultimately related to the properties of photocathodes. In this paper an overview of the recent progress on photocathode development for photoemission electron sources is presented.  
 
THP006 Status of High Current R&D Energy Recovery Linac at Brookhaven National Laboratory electron, gun, SRF, linac 2148
 
  • D. Kayran, Z. Altinbas, D.R. Beavis, I. Ben-Zvi, R. Calaga, D.M. Gassner, H. Hahn, L.R. Hammons, A.K. Jain, J.P. Jamilkowski, N. Laloudakis, R.F. Lambiase, D.L. Lederle, V. Litvinenko, G.J. Mahler, G.T. McIntyre, W. Meng, B. Oerter, D. Pate, D. Phillips, J. Reich, T. Roser, C. Schultheiss, B. Sheehy, T. Srinivasan-Rao, R. Than, J.E. Tuozzolo, D. Weiss, W. Xu, A. Zaltsman
    BNL, Upton, Long Island, New York, USA
 
  An ampere-class 20 MeV superconducting energy recovery linac (ERL) is under construction at Brookhaven National Laboratory (BNL) for testing of concepts relevant for high-energy coherent electron cooling and electron-ion colliders. One of the goals is to demonstrate an electron beam with high charge per bunch (~5 nC) and low normalized emittance (~5 mm-mrad) at an energy of 20 MeV. A flexible lattice for the ERL loop provides a test bed for investigating issues of transverse and longitudinal instabilities and diagnostics for CW beam. A superconducting 703 MHz RF photo-injector is considered as an electron source for such a facility. We will start with a straight pass (gun/cavity/beam stop) test for gun performance studies. Later, we will install and test a novel injection line concept for emittance preservation in a lower-energy merger. Here we present the status and our plans for construction and commissioning of this facility.  
 
THP043 High-performance Accelerators for Free-Electron Laser (FEL) and Security Applications FEL, gun, electron, wiggler 2196
 
  • A.M.M. Todd, H. Bluem, V. Christina, M.D. Cole, D. Dowell, K. Jordan, J.H. Park, J. Rathke, T. Schultheiss, L.M. Young
    AES, Princeton, New Jersey, USA
 
  We describe the status of two accelerators that Advanced Energy Systems has recently designed and built, and is presently commissioning. One system will drive the THz FEL at the Fritz Haber Institute of the Max Planck Society in Berlin, while the other will produce radiation for Homeland Security applications. A key aspect of the required FEL accelerator performance is low longitudinal emittance < 50 keV-psec at 200 pC bunch charge from a thermionic electron source. The other system is compact, robust and efficient since it must be transportable.
Consultants to AES
 
 
THP046 Characterization of an SRF Gun: A 3D Full Wave Simulation gun, simulation, electron, SRF 2205
 
  • E. Wang
    PKU/IHIP, Beijing, People's Republic of China
  • I. Ben-Zvi
    BNL, Upton, Long Island, New York, USA
  • J. Wang
    CST of America, Wellesley Hills, Massachusetts, USA
 
  Funding: Work supported by Brookhaven science Associates, LLC Contract No.DE-AC02-98CH10886 with the U.S.DOE
We characterized a BNL 1.3GHz half-cell SRF gun is tested for GaAs photocathode. The gun already was simulated several years ago via two-dimensional (2D) numerical codes (i.e., Superfish and Parmela) with and without the beam. In this paper, we discuss our investigation of its characteristics using a three dimensional (3D) full-wave code (CST STUDIO SUITE™).The input/pickup couplers are sited symmetrically on the same side of the gun at an angle of 180⁰. In particular, the inner conductor of the pickup coupler is considerably shorter than that of the input coupler. We evaluated the cross-talk between the beam (trajectory) and the signal on the input coupler compared our findings with published results based on analytical models. The CST STUDIO SUITE™ also was used to predict the field within the cavity; particularly, a combination of transient/eigenmode solvers was employed to accurately construct the RF field for the particles, which also includes the effects of the couplers. Finally, we explored the beam’s dynamics with a particle in cell (PIC) simulation, validated the results and compare them with 2D code result.
 
 
THP054 Medium Energy Heavy Ion Operations at RHIC luminosity, ion, heavy-ion, monitoring 2220
 
  • K.A. Drees, L. A. Ahrens, M. Bai, J. Beebe-Wang, I. Blackler, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, J.J. Butler, C. Carlson, R. Connolly, T. D'Ottavio, W. Fischer, W. Fu, D.M. Gassner, M. Harvey, T. Hayes, H. Huang, R.L. Hulsart, P.F. Ingrassia, N.A. Kling, M. Lafky, J.S. Laster, R.C. Lee, V. Litvinenko, Y. Luo, W.W. MacKay, M. Mapes, G.J. Marr, A. Marusic, K. Mernick, R.J. Michnoff, M.G. Minty, C. Montag, J. Morris, C. Naylor, S. Nemesure, F.C. Pilat, V. Ptitsyn, G. Robert-Demolaize, T. Roser, P. Sampson, T. Satogata, V. Schoefer, C. Schultheiss, F. Severino, T.C. Shrey, K.S. Smith, S. Tepikian, P. Thieberger, D. Trbojevic, N. Tsoupas, J.E. Tuozzolo, M. Wilinski, A. Zaltsman, K. Zeno, S.Y. Zhang
    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.
As part of the search for a phase transition or critical point on the QCD phase diagram, an energy scan including 5 different energy settings was performed during the 2010 RHIC heavy ion run. While the top beam energy for heavy ions is at 100 GeV/n and the lowest achieved energy setpoint was significantly below RHICs injection energy of approximately 10 GeV/n, we also provided beams for data taking in a medium energy range above injection energy and below top beam energy. This paper reviews RHIC experience and challenges for RHIC medium energy operations that produced full experimental data sets at beam energies of 31.2 GeV/n and 19.5 GeV/n.
 
 
THP067 Ambient Beam Motion and its Excitation by "Ghost Lines" in the Tevatron betatron, proton, quadrupole, focusing 2255
 
  • V.D. Shiltsev
    Fermilab, Batavia, USA
 
  Transverse betatron motion of the Tevatron proton beam is measured and analyzed. It is shown that the motion is coherent and excited by external sources of unknown origins. Observations of the time-varying "ghost lines" in the betatron spectrum are reported.  
 
THP073 Simulations of Emittance Measurement at CLIC collider, laser, simulation, quadrupole 2270
 
  • Yu.A. Kubyshin, H. Garcia
    UPC, Barcelona, Spain
  • E. Marin, D. Schulte, F. Stulle
    CERN, Geneva, Switzerland
 
  A proposal for a CLIC emittance measurement line using laser-wire beam profile monitors is presented. Results of simulations and optimizations are given. Estimates of the impact of beam size as well as statistical and machine-related errors on the measurement accuracy are discussed.  
 
THP079 Recent RHIC-motivated Polarized Proton Developments in the Brookhaven AGS resonance, polarization, quadrupole, proton 2282
 
  • V. Schoefer, L. A. Ahrens, M. Bai, S. Binello, M. Blaskiewicz, K.A. Brown, C.J. Gardner, J.W. Glenn, H. Huang, F. Lin, W.W. MacKay, J. Morris, S. Nemesure, T. Roser, S. Tepikian, N. Tsoupas, K. Yip, A. Zelenski, K. Zeno
    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 RHIC polarized proton physics program requires high luminosity and high polarization which depends directly on the intensity, emittances and polarization delivered to RHIC by the injector chain. In the AGS, two partial snakes create gaps in the realized spin-tune around the integers which allows an accelerating beam with sufficiently small vertical emittance and near-integer vertical tune to avoid the imperfection and vertical intrinsic resonances. The same strategy strengthens the many (82) weak horizontal intrinsic resonances crossed during AGS acceleration. A system speeding up these resonance crossings – the AGS JumpQuad system: 82 tiny (0.04) fast (100usec) betatron tune shifts – has been commissioned and evolved during RHIC Runs 09, 10, and 11. Subtle properties of the AGS geometry and lattice, magnified into relevance by the high vertical tune can result in polarization-damaging emittance growth when combined with the Jump Quad gymnastics. Orbit stability is critical. Some aspects of the JumpQuad system, of this commissioning effort and related developments will be described.
 
 
THP081 Beam Lifetime and Limitations during Low-Energy RHIC Operation space-charge, ion, collider, luminosity 2285
 
  • A.V. Fedotov, M. Bai, M. Blaskiewicz, W. Fischer, D. Kayran, C. Montag, T. Satogata, S. Tepikian, G. Wang
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work performed under contract No. DE-AC02-98CH10886 with the auspices of the DoE of United States.
The low-energy physics program at the Relativistic Heavy Ion Collider (RHIC), motivated by a search for the QCD phase transition critical point, requires operation at low energies. At these energies, large nonlinear magnetic field errors and large beam sizes produce low beam lifetimes. A variety of beam dynamics effects such as Intrabeam Scattering (IBS), space charge and beam-beam forces also contribute. All these effects are important to understand beam lifetime limitations in RHIC at low energies. During the low-energy RHIC physics run in May-June 2010 at beam γ=6.1 and γ=4.1, gold beam lifetimes were measured for various values of space-charge tune shifts, transverse acceptance limitation by collimators, synchrotron tunes and RF voltage. This paper summarizes our observations and initial findings.
 
 
THP082 Design Aspects of an Electrostatic Electron Cooler for Low-energy RHIC Operation electron, ion, luminosity, undulator 2288
 
  • A.V. Fedotov, I. Ben-Zvi, J. Brodowski, X. Chang, D.M. Gassner, L.T. Hoff, D. Kayran, J. Kewisch, B. Oerter, A. Pendzick, S. Tepikian, P. Thieberger
    BNL, Upton, Long Island, New York, USA
  • L.R. Prost, A.V. Shemyakin
    Fermilab, Batavia, USA
 
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
Electron cooling was proposed to increase the luminosity of RHIC operation for heavy ion beam energies below 10 GeV/nucleon. The electron cooling system needed should be able to deliver an electron beam of adequate quality in a wide range of electron beam energies (0.9-5 MeV). An option of using an electrostatic accelerator for cooling heavy ions in RHIC was studied in detail. In this paper, we describe the requirements and options to be considered in the design of such a cooler for RHIC, as well as the associated challenges. The expected luminosity improvement and limitations with such electron cooling system are also discussed.
 
 
THP114 Status of the PEP-X Light Source Design Study photon, FEL, linac, brightness 2336
 
  • R.O. Hettel, K.L.F. Bane, K.J. Bertsche, Y. Cai, A. Chao, X. Huang, Y. Jiao, C.-K. Ng, Y. Nosochkov, A. Novokhatski, T. Rabedeau, C.H. Rivetta, J.A. Safranek, G.V. Stupakov, L. Wang, M.-H. Wang, L. Xiao
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported in part by Department of Energy Contract DE-AC02-76SF00515 and Office of Basic Energy Sciences, Division of Chemical Sciences.
The SLAC Beam Physics group and collaborators continue to study options for implementing a near diffraction-limited ring-based light source in the 2.2-km PEP-II tunnel that will serve the SSRL scientific program in the future. The study team has completed the baseline design for a 4.5-GeV storage ring having 160-pm-rad emittance with stored beam current of 1.5 A, providing >1022 brightness for multi-keV photon beams from 3.5-m undulator sources. The team is now investigating possible 5-GeV ERL configurations which, similar to the Cornell and KEK ERL plans, would have ~30 pm-rad emittance with 100 mA current, and ~10 pm-rad emittance with 25 mA or less. In the next year, a diffraction-limited storage ring using on-axis injection in order to reach 30 pm-rad or less emittance will be investigated. An overview of the PEP-X design study and SSRL’s plans for defining the performance parameters that will guide the choice of implementation options is presented.
 
 
THP119 Potential Two-fold Reduction of Advanced Photon Source Emittance using Orbit Displacement lattice, quadrupole, sextupole, damping 2339
 
  • M. Borland
    ANL, Argonne, 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.
The Advanced Photon Source (APS) is a 7-GeV electron storage ring light source that operates with an effective emittance of 3.1 nm using optics with distributed dispersion. Lower emittance is desirable for some x-ray experiments, but is difficult using conventional optics adjustments because of the required strength of quadrupoles and sextupoles. Changing the damping partition number by changing the rf frequency is another approach, but is incompatible with distributed dispersion because it would require simultaneous realignment of all APS beamlines. In this paper, we evaluate a new approach to changing the damping partition number using a systematic orbit bump in all sectors.
 
 
THP120 Light Sources Optimized with Super Bends dipole, storage-ring, photon, brightness 2342
 
  • L. Emery
    ANL, Argonne, USA
  • C. Steier
    LBNL, Berkeley, California, USA
 
  Funding: Work at Argonne was supported by U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract No. DE-AC02-06CH11357
In the past small storage rings with dipole-magnet-only sources were called second-generation light sources (before insertion devices (IDs) were used). With today's technology, e.g. superconducting dipole magnet of 5 T (e.g., ALS's Superbend *), one could make a smaller ring (say, 60-m circumference) with substantial brightness for dipole-magnet beams. Without IDs, these optimized sources would be designated as between second and third generation. Such rings don't exist yet, but their concept can be compared with other types of compact light sources. Typical parameters of such ring would be 60-m circumference, 2 GeV, several 5-T dipole sources in TME-like cells, and 4x1013 photons/s/0.1% BW at 1 Angstrom. The number of beamlines is variable, but potentially very large, only limited by funding.
* D. Robin et al., NIM A 538, 1-3, (2005), 65-92.
 
 
THP129 Emittance Reduction Approaches for NSLS-II damping, lattice, wiggler, dipole 2363
 
  • W. Guo, F.J. Willeke
    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
NSLS-II is a third generation light source that is under construction at the Brookhaven National Laboartory. The 3GeV 792m long 30-cell storage ring will be commissioned in 2014. The emittance is lowered from 2nm to 1nm by three 7m damping wigglers. This paper will discuss the future emittance reduction approaches for NSLS-II. One option is installing more damping wigglers; an alternative solution is to manipulate the damping partition by shifting the chromatic quadrupoles horizontally. Both methods can lower the emittance effectively; however, the second method does not occupy the user straights. When the quarupoles are moved, the orbit and thus the vacuum chamber need to be redesigned, and beam dynamics could be affected. In the paper we will compare the lattice properties for the two options, and address the potential issues.
 
 
THP133 Modulation of Low Energy Beam to Generate Predefined Bunch Trains for the NSLS-II Top-off Injection linac, gun, kicker, storage-ring 2372
 
  • G.M. Wang, W.X. Cheng, R.P. Fliller, R. Heese, J. Rose, T.V. Shaftan
    BNL, Upton, Long Island, New York, USA
 
  Funding: Work supported by U.S. DOE, Contract No.DE-AC02-98CH10886
The NSLS II linac will produce a bunch train, 80-150 bunches long with 2 ns bunch spacing. Having the ability to tailor the bunch train can lead to the smaller bunch to bunch charge variation in the storage ring. A stripline is integrated into the linac baseline to achieve this tailoring. The stripline must have a fast field rise and fall time to tailor each bunch. The beam dynamics is minimally affected by including the extra space for the stripline. This paper discusses the linac beam dynamics with stripline, and the optimal design of the stripline.
 
 
THP144 FELs as X-ray Sources in ERL Facilities FEL, radiation, electron, linac 2390
 
  • A. Meseck
    HZB, Berlin, Germany
  • G.H. Hoffstaetter, F. Löhl, C.E. Mayes
    CLASSE, Ithaca, New York, USA
 
  Funding: This work has been supported by NSF award DMR-0807731.
Hard x-ray Energy Recovery Linacs (ERLs) operate with high-brightness electron beams, matching the requirements for X-ray FELs in terms of emittance and energy spread. We have analyzed in how far it is feasible to include X-ray FELs in ERL facilities. X-ray FEL Oscillators require comparatively low peak currents and are therefore good candidates for FEL sources in ERLs. However, also high-gain FELs do not seem out of reach when bunch-compression schemes for higher peak currents are utilized. Using the proposed Cornell ERL as an example, different FEL concepts are discussed and their suitability as X-ray sources are analyzed.
 
 
THP162 Design Studies of Coherent Prebunching and Emittance Reduction for the MaRIE XFEL bunching, electron, undulator, FEL 2414
 
  • Q.R. Marksteiner, K. Bishofberger, B.E. Carlsten, L.D. Duffy, N.A. Yampolsky
    LANL, Los Alamos, New Mexico, USA
 
  Funding: Supported by US Department of Energy Grant LDRD 20110067DR.
There are several schemes currently being investigated which use modulator and dispersive sections to step the coherent bunching of the electron beam up to higher harmonics. X-ray FELs generally operate in a regime where the FEL parameter ρ is equal to or less than the effective energy spread introduced from the emittance in the electron beam. Because of this large effective energy spread, the energy modulation introduced from harmonic generation schemes would seriously degrade FEL performance. This problem can be mitigated by incorporating the harmonic generation scheme at an electron kinetic energy lower than the energy at the final undulator. This will help because the effective energy spread from emittance is reduced at lower energies, and can be further reduced by making the beam transversely large. Then the beam can be squeezed down slowly enough in the subsequent accelerator sections so that geometric debunching is avoided. Here we show analytical results that demonstrate the feasibility of this harmonic pre-bunching scheme.
 
 
THP180 Studies of a Linac Driver for a High Repetition Rate X-ray FEL linac, FEL, simulation, laser 2450
 
  • M. Venturini, J.N. Corlett, L.R. Doolittle, D. Filippetto, C. F. Papadopoulos, G. Penn, D. Prosnitz, J. Qiang, M.W. Reinsch, R.D. Ryne, F. Sannibale, J.W. Staples, R.P. Wells, J.S. Wurtele, M.S. Zolotorev
    LBNL, Berkeley, California, USA
  • A. Zholents
    ANL, Argonne, USA
 
  Funding: Work carried out under Department of Energy contract No. DE-AC02-0SCK11231
We report on on-going studies of a superconducting CW linac driver intended to support a high repetition rate FEL operating in the soft x-rays spectrum. We present a point-design for a 1.8 GeV machine tuned for 300~pC bunches and delivering low-emittance, low-energy spread beams as needed for the SASE and seeded beamlines.
 
 
THP186 Lattice Design for ERL Options at SLAC linac, injection, lattice, extraction 2465
 
  • Y. Nosochkov, Y. Cai, X. Huang, M.-H. Wang
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by the U.S. Department of Energy under Contract number DE-AC02 76SF00515.
SLAC is investigating long-range options for building a high performance light source machine while reusing the existing linac and PEP-II tunnels. One previously studied option is the PEP-X low emittance storage ring. The alternative option is based on a superconducting Energy Recovery Linac (ERL) and the PEP-X design. The ERL advantages are the low beam emittance, short bunch length and small energy spread leading to better qualities of the X-ray beams. Two ERL configurations differed by the location of the linac have been studied. Details of the lattice design and the results of beam transport simulations with the coherent synchrotron radiation effects are presented
 
 
THP187 Design Concept for a Compact ERL to Drive a VUV/Soft X-Ray FEL FEL, quadrupole, linac, wiggler 2468
 
  • C. Tennant, D. Douglas
    JLAB, Newport News, Virginia, USA
 
  Funding: Support by US DOE contract #DE-AC05-060R23177
We explore possible upgrades of the existing Jefferson Laboratory IR/UV FEL driver to higher electron beam energy and shorter wavelength through use of multipass recirculation to drive an amplifier FEL. The system would require beam energy at the wiggler of 600 MeV with 1 mA of average current. The system must generate a high brightness beam, configure it appropriately, and preserve beam quality through the acceleration cycle - including multiple recirculations - and appropriately manage the phase space during energy recovery. The paper will discuss preliminary design analysis of the longitudinal match, space charge effects in the linac, and recirculator design issues, including the potential for the microbunching instability. A design concept for the recirculator and a lattice solution will be presented.
 
 
THP192 Effect of Surface Roughness on the Emittance from GaAs Photocathode electron, cathode, gun, extraction 2480
 
  • S.S. Karkare, I.V. Bazarov
    Cornell University, Ithaca, New York, USA
  • L. Cultrera, A. Iyer, X. Liu, W.J. Schaff
    CLASSE, Ithaca, New York, USA
 
  Funding: This work is supported by NSF under Grant No. DMR- 0807731 and DOE under Grant No. DE-SC0003965.
The surface roughness of GaAs photocathodes used in the injector prototype for the ERL at Cornell University was measured and compared to that of the atomically polished GaAs crystal surface using the atomic force microscopy (AFM) technique. The results show at least an order of magnitude rise in the GaAs surface roughness after subjecting it to heat cleaning, prior to activation. An analytical model for photoemission that takes into account the effect of surface roughness has been developed. This model predicts emittance values close to the experimental observations, explains the experimentally observed variation of emittance with incident light wavelength and reconciles the discrepancies in experimental data.
 
 
THP196 High Power Beam Test of a 1.6-cell Photocathode RF Gun at PAL gun, electron, coupling, simulation 2486
 
  • M.S. Chae, J.H. Hong, I.S. Ko, Y.W. Parc
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • C. Kim, S.J. Park
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  Funding: This work was supported by the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (MEST) (grant No. 2008-0059842)
The photocathode RF gun with four holes at the side of the full cell will be tested soon at the gun test stand which consists of a 1.6 cell cavity, a solenoid magnet, beam diagnostic components and auxiliary systems such as ICT, spectrometer, YAG scintillator and screens, Faraday cup, etc. Basic diagnostics such as the measurements of charge, energy and its spread, transverse emittance will be performed. It is expected that these diagnostics will confirm a successful fabrication of the RF gun. In this presentation, we will show the status of the RF gun aging in PAL and detail plan of measurements on various beam parameters. The results with the simulation code PARMELA will be presented to prepare measurement devices properly.
 
 
THP200 Photoinjector Beam Dynamics for a Next Generation X-Ray FEL space-charge, FEL, bunching, laser 2495
 
  • C. F. Papadopoulos, J.N. Corlett, D. Filippetto, G. Penn, J. Qiang, F. Sannibale, J.W. Staples, M. Venturini, R.P. Wells, M.S. Zolotorev
    LBNL, Berkeley, California, USA
 
  Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
In this paper, we will present the status of the beam dynamics simulations for a Next Generation Light Source (NGLS) injector, based on a high repetition rate (1 MHz), high brightness design. A multi-stage beam compression scheme is proposed, based on the concepts of velocity bunching and emittance compensation. For the optimization of the design parameters we use a genetic algorithm approach, and we focus on a mode providing charges of 300 pC, with normalized transverse emittance less than 0.6 microns, suitable to operate a next generation light source based on an X-ray FEL. In addition, we discuss the effects of bunch compression and linearity of the transverse and longitudinal phase space of the beam.
 
 
THP215 Performance of the Diagnostics for NSLS-II Linac Commissioning linac, booster, diagnostics, simulation 2525
 
  • R.P. Fliller, R. Heese, H.-C. Hseuh, M.P. Johanson, B.N. Kosciuk, D. Padrazo, I. Pinayev, J. Rose, T.V. Shaftan, O. Singh, G.M. Wang
    BNL, Upton, Long Island, New York, USA
 
  Funding: This manuscript has been authored by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
The National Synchrotron Light Source II (NSLS-II) is a state of the art 3 GeV third generation light source currently under construction at Brookhaven National Laboratory. The NSLS-II injection system consists of a 200 MeV linac and a 3 GeV booster synchrotron and associated transfer lines. The transfer lines not only provide a means to delivering the beam from one machine to another, they also provide a suite of diagnostics and utilities to measure the properties of the beam to be delivered. In this paper we discuss the suite of diagnostics that will be used to commission the NSLS-II linac and measure the beam properties. The linac to booster transfer line can measure the linac emittance with a three screens measurement or a quadrupole scan. Energy and energy spread are measured in a dispersive section. Total charge and charge uniformity are measured with wall current monitors in the linac and transformers in the transfer line. We show that the performance of the transfer line will be sufficient to ensure the linac meets its specifications and provides a means of trouble shooting and studying the linac in future operation.
 
 
THP222 Drive Laser System for the Advanced Photo-Injector Project at the LBNL laser, cathode, electron, controls 2537
 
  • J. Feng, D. Filippetto, H.A. Padmore, F. Sannibale, R.P. Wells
    LBNL, Berkeley, California, USA
  • M. J. Messerly, M.A. Prantil
    LLNL, Livermore, California, USA
 
  Funding: This work was supported by the Director of the Office of Science of the US Department of Energy under Contract no. DEAC02-05CH11231.
The electron photo-gun of the Advanced Photo-injector EXperiment project (APEX) at the LBNL will be driven by a compact fiber laser for different photo-cathode experiments during the initial phase of the project. The fiber laser, developed at the Lawrence Livermore National Laboratory, is designed to deliver μJ/pulse at 1064 nm system that is frequency doubled to deliver light at 532nm with 1MHz repetition rate and 1ps pulse length optimized for photo-emission with multi-alkali antimonide cathodes. For Cs2Te and diamond amplifier cathodes, the 4th harmonic will be generated by doubling frequency again in a non-linear crystal. Due to the requirement of small emittance for the electron beam, the laser pulse will be shaped in space and time for 532nm and UV lights, in general with a constant intensity in cross section with a sharp radial cutoff, and elliptical or rectangular distribution in the longitudinal plane. Diagnostics of the laser beam itself and of the cathode will be integrated with techniques such as cross- correlation, streak camera, and virtual cathode imaging, not only to monitor the laser pulse but also to provide automated feedbacks.
 
 
THP223 Laser Systems for Livermore's Mono-Energetic Gamma-Ray Source laser, electron, scattering, photon 2540
 
  • D.J. Gibson, F. Albert, C.P.J. Barty, A.J. Bayramian, C.A. Ebbers, F.V. Hartemann, R.A. Marsh, M. J. Messerly
    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.
A Mono-energetic Gamma-Ray (MEGa-Ray) source, based on Compton scattering of a high-intensity laser beam off a highly relativistic electron beam, requires highly specialized laser systems. To minimize the bandwidth of the gamma-ray beam, the scattering laser must have minimal bandwidth, but also match the electron beam depth of focus in length. This requires a ~1 J, 10 ps, fourier-transform-limited laser system. Also required is a high-brightness electron beam, best provided by a photoinjector. This electron source in turn requires a second laser system with stringent requirements on the beam including flat transverse and longitudinal profiles and fast rise times. Furthermore, these systems must be synchronized to each other with ps-scale accuracy. Using a novel hyper-dispersion compressor configuration, advanced fiber amplifiers, and diode-pumped Nd:YAG amplifiers, we have designed laser systems that meet these challenges for the x-band photoinjector and Compton-scattering source being built at Lawrence Livermore National Laboratory.
 
 
FROAN4 Femtosecond RF Gun Based MeV Electron Diffraction electron, gun, laser, cathode 2558
 
  • J. Yang, K. Kan, Y. Murooka, N. Naruse, K. Tanimura, Y. Yoshida
    ISIR, Osaka, Japan
  • J. Urakawa
    KEK, Ibaraki, Japan
 
  Ultrafast time-resolved electron diffraction based on a photocathode rf electron gun is being developed in Osaka University to reveal the hidden dynamics of intricate molecular and atomic processes in materials. A new structure rf gun has been developed to generates a low-emittance femtosecond-bunch electron beam, and has been used successfully for the single-shot MeV electron diffraction measurement. The transverse emittance, bunch length and energy spread were measured. The growths of the emittance, bunch length and energy spread due to the rf and the space charge effects in the rf gun were investigated by changing the laser injection phase, the laser pulse width and the bunch charge. The same demonstrations of the electron diffraction measurement were reported.  
slides icon Slides FROAN4 [5.097 MB]