Keyword: emittance
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MOOCB03 A Novel Method for Quasi-non-interceptive Beam Profile Measurement in a Linac linac, coupling, diagnostics, beam-transport 50
 
  • A.V. Aleksandrov
    ORNL, Oak Ridge, Tennessee, USA
 
  Funding: SNS is managed by UT-Battelle, LLC, under contract DE-AC05-00OR22725 for the U.S. Department of Energy.
Beam profile diagnostics is an important tool for understanding beam dynamics in accelerators. Non-interceptive diagnostics have many great advantages but often are difficult in implementation. We suggest a method of measuring beam profiles that is not truly non-interceptive, because beam has to be intercepted at some point, preferably in the beginning of the linac. But significant difference from a conventional interceptive measurement is that beam is not intercepted at any of the points of measurement along the linac. One important application is measuring beam profiles within cryostats of a super-conducting linac. The equipment required for implementing this diagnostic is simple: a set of slits in the beginning of the accelerator, and a Beam Position Monitor (BPM) in the point of measurement. Beam profiles can be measured simultaneously at every BPM along the linac. In this paper we will discuss details of the method, its limitations, and effect of non-linearity, coupling and space charge. Results of a demonstration experiment at SNS will be presented and discussed.
 
slides icon Slides MOOCB03 [3.365 MB]  
 
MOODB01 Dynamics of the IFMIF Very High-intensity Beam rfq, space-charge, linac, cryomodule 53
 
  • P.A.P. Nghiem, R.D. Duperrier, A. Mosnier, D. Uriot
    CEA/DSM/IRFU, France
  • N. Chauvin, O. Delferrière, W. Simeoni
    CEA/IRFU, Gif-sur-Yvette, France
  • M. Comunian
    INFN/LNL, Legnaro (PD), Italy
  • C. Oliver
    CIEMAT, Madrid, Spain
 
  For the purpose of material studies for future nuclear fusion reactors, the IFMIF deuteron beams present a simultaneous combination of unprecedentedly high intensity (2x125 mA CW), power (2x5 MW) and space charge. Special considerations and new concepts have been developed in order to overcome these challenges. The global strategy for beam dynamics design in the 40 MeV IFMIF accelerators is presented, stressing on the control of micro-losses, and the possibility of on-line fine tuning. The obtained results are then analysed in terms of beam halo and emittance growth.  
slides icon Slides MOODB01 [3.807 MB]  
 
MOPC022 Development of a Compact C-band Photocathode RF Gun gun, electron, cathode, injection 116
 
  • X.H. Liu, H. Chen, W.-H. Huang, H.J. Qian, C.-X. Tang, Z. Zhang
    TUB, Beijing, People's Republic of China
 
  Funding: This work is supported by National Natural Science Foundation of China and National Basic Research Program of China (973 Program).
A C-band photocathode RF gun for a compact electron diffraction facility is developed in Tsinghua University, which is designed to work at the frequency of 5.712GHz. This paper presents the physics and structure design of this C-band RF gun, and the comparison on beam dynamics of S-band and C-band photoinjector has been done. Some new structure design will be adopted in this gun, including the optimized cavity length and elliptical iris, which is helpful to achieve lower emittance and larger mode separation.
 
 
MOPC033 The Status of a 1.6-cell Photocathode RF Gun at PAL gun, cavity, klystron, cathode 142
 
  • M.S. Chae, J.H. Hong, I.S. Ko, Y.W. Parc
    POSTECH, Pohang, Kyungbuk, Republic of Korea
  • S.J. Park
    PAL, Pohang, Kyungbuk, Republic of Korea
 
  The RF power conditioning of the photocathode RF gun with four holes at the side of the full cell named as 'Pohang gun' is in progress. The first goal of the conditioning is the operation of the gun with RF pulse width of 1.5 μm, repetition rate of 30 Hz, field gradient at the cathode of 130 MV/m. We operated the RF gun successfully with the conditions within last few months. It was first operational experience with such conditions in PAL. Now we have a plan to operate RF gun with higher repetition rate up to 60 Hz.  
 
MOPC040 The Measurement of Transversal Shunt Impedance of RF Deflector cavity, impedance, simulation, dipole 163
 
  • A.Yu. Smirnov, M.V. Lalayan, N.P. Sobenin
    MEPhI, Moscow, Russia
  • A.A. Zavadtsev
    Nano, Moscow, Russia
 
  This paper presents the results of transverse shunt impedance measurement performed using field perturbation technique and comparison with numerical MWS simulations. The structure under test is the S-band 3-cell deflecting cavity. The mentioned cavity operates with a dipole TM11-like mode with a phase shift of 120 deg per cell. The analyses were carried out with use of two types of perturbing beads: dielectric beads and metallic rings. The latter type perturbs the on-axis magnetic field much stronger than the electric field, which allows us calculating transversal shunt impedance using on-axis EM fields values.  
 
MOPC054 The LHC RF System - Experience with Beam Operation synchrotron, injection, klystron, damping 202
 
  • P. Baudrenghien, M. E. Angoletta, T. Argyropoulos, L. Arnaudon, J. Bento, T. Bohl, O. Brunner, A.C. Butterworth, E. Ciapala, F. Dubouchet, J. Esteban Muller, D.C. Glenat, G. Hagmann, W. Höfle, D. Jacquet, M. Jaussi, S. Kouzue, D. Landre, J. Lollierou, P. Maesen, P. Martinez Yanez, T. Mastoridis, J.C. Molendijk, C. Nicou, J. Noirjean, G. Papotti, A.V. Pashnin, G. Pechaud, J. Pradier, J. Sanchez-Quesada, M. Schokker, E.N. Shaposhnikova, D. Stellfeld, J. Tückmantel, D. Valuch, U. Wehrle, F. Weierud
    CERN, Geneva, Switzerland
 
  The LHC RF system commissioning with beam and physics operation for 2010 and 2011 are presented. It became clear in early 2010 that RF noise was not a lifetime limiting factor: the crossing of the much feared 50 Hz line for the synchrotron frequency did not affect the beam. The broadband LHC RF noise is reduced to a level that makes its contribution to beam diffusion in physics well below that of Intra Beam Scattering. Capture losses are also under control, at well below 0.5%. Longitudinal emittance blow-up, needed for ramping of the nominal intensity single bunch, was rapidly commissioned. In 2011, 3.5 TeV/beam physics has been conducted with 1380 bunches at 50 ns spacing, corresponding to 55% of the nominal current. The intensity per bunch (1.3 ·1011 p) is significantly above the nominal 1.15 ·1011. By August 2011 the LHC has accumulated more than 2 fb-1 integrated luminosity, well in excess of the 1 fb-1 target for 2011.  
 
MOPC057 Loss of Landau Damping in the LHC damping, injection, acceleration, impedance 211
 
  • E.N. Shaposhnikova, T. Argyropoulos, P. Baudrenghien, T. Bohl, A.C. Butterworth, J. Esteban Muller, T. Mastoridis, G. Papotti, J. Tückmantel, W. Venturini Delsolaro, U. Wehrle
    CERN, Geneva, Switzerland
  • C.M. Bhat
    Fermilab, Batavia, USA
 
  Loss of Landau damping leading to a single bunch longitudinal quadrupole instability has been observed in the LHC during the ramp and on the 3.5 TeV flat top for small injected longitudinal emittances. The first measurements are in good agreement with the threshold calculated for the expected longitudinal reactive impedance budget of the LHC as well as with the threshold dependence on beam energy. The cure is a controlled longitudinal emittance blow-up during the ramp which for constant threshold through the cycle should provide an emittance proportional to the square root of energy.  
 
MOPC058 Upgrade of the 200 MHz RF System in the CERN SPS cavity, impedance, extraction, acceleration 214
 
  • E.N. Shaposhnikova, E. Ciapala, E. Montesinos
    CERN, Geneva, Switzerland
 
  The 200 MHz RF system, used in the SPS to accelerate all beams including those for the LHC, has four travelling wave structure cavities of different length. To stabilize the future higher intensity LHC beams in the SPS a larger (than now) controlled longitudinal emittance blow-up and therefore larger bucket and voltage amplitude will be necessary. However less voltage will be available in the existing system (which has a maximum peak RF power of 1 MW per cavity) due to the increased beam loading, in particular in the long cavities. This issue will be critical for beam acceleration but especially for beam transfer into the 400 MHz RF system of the LHC. The proposed solution is to shorten the two long cavities and use the freed sections together with spare sections to make two extra cavities and install two new power plants of 1.3 MW each. After this upgrade, which is a major part of the more general SPS upgrade for high luminosity LHC to be completed during 2017, the performance of the SPS RF system with high intensity beams will be significantly improved and at the same time the total impedance of the system will be reduced.  
 
MOPC109 Suppression of Coupler Kicks in 7-Cell Main Linac Cavities for Cornell's ERL cavity, linac, resonance, simulation 331
 
  • N.R.A. Valles, M. Liepe, V.D. Shemelin
    CLASSE, Ithaca, New York, USA
 
  Funding: Supported by NSF award DMR-0807731
Cornell is developing a 5 GeV Energy Recovery Linac operating at 100 mA with very small emittances (~30 pm at 77 pC bunch charge) in the horizontal and vertical directions. We investigate the effect of the fundamental RF power couplers of the main linac SRF cavities on the beam using the ACE3P software package. The cavities in the ERL main linac will be operated at very high loaded quality factors of up to 6.5·107, corresponding to a full bandwidth of only 20 Hz. Cavity microphonics will detune the cavities by more than one bandwidth during operation, thereby causing a time dependent change of the coupler kick in addition to its fast oscillation at the RF frequency. In order to investigate the dependence of the coupler kick on the cavity frequency, we calculate the coupler kick given to the beam for the case of a detuned RF cavity. We show that a compensation stub geometry located opposite to the input coupler port can be optimized to reduce the overall kick given to the beam and the emittace growth caused by its time dependence.
 
 
MOPO013 Suppression of Emittance Growth by Excited Magnet Noise with the Transverse Damper in LHC in Simulations and Experiment pick-up, feedback, betatron, simulation 508
 
  • W. Höfle, G. Arduini, R. De Maria, G. Kotzian, D. Valuch
    CERN, Geneva, Switzerland
  • V.A. Lebedev
    Fermilab, Batavia, USA
 
  The LHC transverse dampers initially build to control transverse instabilities are also a good remedy to suppress the oscillations causing emittance growth excited by electro-magnetic noises at the frequencies of betatron sidebands. To prevent the emittance growth excited by magnet noise using the damper this system has to have extremely low noise properties. The paper discusses simulation results on the effectiveness of the transverse feedback system to suppress such oscillations and the experimental results from a damper point of view as they were gained during the 2010 LHC run. Possible improvements in the damper system to enhance its effectiveness with respect to the suppression of emittance blow-up are also discussed.  
 
MOPO042 Photonic Crystal Fibre Laser for Electron Beam Emittance Measurement* laser, electron, diagnostics, extraction 577
 
  • L. Corner, L.J. Nevay, R. Walczak
    Oxford University, Physics Department, Oxford, Oxon, United Kingdom
 
  We discuss the recent progress in the development of a high repetition rate, high energy fibre laser for intratrain laser-wire scans of transverse electron beam sizes. A commercial fibre laser (1uJ, 6.49MHz) is amplified in rod type photonic crystal fibre using a burst mode format, which has the advantage of allowing us to exploit very high transient gain while reducing the heat load deposited in the amplifier. The amplified pulses are over 180uJ spaced at 154ns, suitable for intratrain scanning at the ATF2. The spatial beam quality is excellent (M2 = 1.07), indicating that it will be possible to focus the laser to a spot size of ~ λ, enabling us to reach high intensities. The amplified pulse duration is 200ps, which can be compressed to less than the electron bunch length to increase the laser-wire signal to noise ratio. The performance of the laser system is analysed with respect to the demands of the laser-wire experiment.  
 
MOPS008 Simulation of Longitudinal Emittance Control in J-PARC RCS for 400 MeV Injection extraction, injection, simulation, bunching 607
 
  • M. Yamamoto, M. Nomura, A. Schnase, T. Shimada, F. Tamura
    JAEA/J-PARC, Tokai-mura, Japan
  • E. Ezura, K. Hara, K. Hasegawa, C. Ohmori, A. Takagi, K. Takata, M. Toda, M. Yoshii
    KEK, Ibaraki, Japan
 
  The injection energy upgrade of the J-PARC RCS from 181 MeV to 400 MeV is scheduled, this is necessary to achieve the design beam intensity. The high intensity beam is delivered to the MR, and the space charge effect at the MR injection should be alleviated by optimizing the longitudinal beam emittance at RCS extraction. This is realized by matching the shape of the beam emittance between the RCS and the MR. We describe the results of particle tracking simulation with the longitudinal emittance control during the whole acceleration period of the RCS.  
 
MOPS009 Probing Intensity Limits of LHC-type Bunches in the CERN SPS with Nominal Optics injection, single-bunch, optics, extraction 610
 
  • B. Salvant, G. Adrian, D.J. Allen, O. Andujar, T. Argyropoulos, J. Axensalva, J. Baldy, H. Bartosik, S. Cettour Cave, F. Chapuis, J.F. Comblin, K. Cornelis, D.G. Cotte, K. Cunnington, H. Damerau, M. Delrieux, J.L. Duran-Lopez, A. Findlay, J. Fleuret, F. Follin, P. Freyermuth, H. Genoud, S.S. Gilardoni, A. Guerrero, S. Hancock, K. Hanke, O. Hans, R. Hazelaar, W. Höfle, L.K. Jensen, J. Kuczerowski, Y. Le Borgne, R. Maillet, D. Manglunki, S. Massot, E. Matli, G. Metral, B. Mikulec, E. Métral, J.-M. Nonglaton, E. Ovalle, L. Pereira, F.C. Peters, A. Rey, J.P. Ridewood, G. Rumolo, J.L. Sanchez Alvarez, E.N. Shaposhnikova, R.R. Steerenberg, R.J. Steinhagen, J. Tan, B. Vandorpe, E. Veyrunes
    CERN, Geneva, Switzerland
 
  Some of the upgrade scenarios of the high-luminosity LHC require large intensity per bunch from the injector chain. Single bunch beams with intensities of up to 3.5 to 4·1011 p/b and nominal emittances were successfully produced in the PS Complex and delivered to the SPS in 2010. This contribution presents results of studies with this new intense beam in the SPS to probe single bunch intensity limitations with nominal gamma transition. In particular, the vertical Transverse Mode Coupling Instability (TMCI) threshold with low chromaticity was observed at 1.6·1011 p/b for single nominal LHC bunches in the SPS. With increased vertical chromaticity, larger intensities could be injected, stored along the flat bottom and accelerated up to 450 GeV/c. However, significant losses and/or transverse emittance blow up were then observed. Longitudinal and transverse optimization efforts in the PSB, PS and SPS were put in place to minimize this beam degradation and succeeded to obtain single 2.3·1011 p/b LHC type bunches with satisfying parameters at extraction of the SPS.  
 
MOPS010 Experimental Studies with Low Transition Energy Optics in the SPS optics, injection, single-bunch, damping 613
 
  • H. Bartosik, T. Argyropoulos, T. Bohl, S. Cettour Cave, K. Cornelis, J. Esteban Muller, Y. Papaphilippou, G. Rumolo, B. Salvant, E.N. Shaposhnikova, J. Wenninger
    CERN, Geneva, Switzerland
 
  The optics of the SPS can be tuned to lower transition energy such that the slippage factor at injection is raised by a factor of almost 3. From theory, an increase of the intensity thresholds for transverse mode coupling, longitudinal coupled bunch and longitudinal instabilities due to the loss of Landau damping can be expected. In this paper, experimental studies in the SPS with single bunches of protons with intensities of up to 3.5·1011 p/b on the flat bottom and at 450 GeV/c are presented. Longitudinal instabilities were studied with LHC-type beams with 50~ns spacing and injected intensities up to 1.8·1011 p/b. The measurements address the increase of intensity thresholds and the achievable transverse emittances in the new low gamma transition optics with respect to the nominal SPS optics. The obtained results are compared with numerical simulations.  
 
MOPS011 Impact of Low Transition Energy Optics to the Electron Cloud Instability of LHC Beams in the SPS electron, optics, simulation, synchrotron 616
 
  • H. Bartosik, E. Benedetto, K.S.B. Li, Y. Papaphilippou, G. Rumolo
    CERN, Geneva, Switzerland
 
  One of the main limitations for high intensity multi-bunch LHC proton beams in the SPS is imposed by electron cloud instabilities. A new optics of the SPS with lower transition energy was implemented and successfully tested in machine studies. The significant increase of the slippage factor that it provides at injection energy results in the expected increase of the single bunch instability thresholds. In this paper, the impact of this new optics on the electron cloud instability threshold is estimated by using numerical simulations, taking into account the change of the optics functions and the faster synchrotron motion due to the reduced transition energy.  
 
MOPS012 Optics Considerations for Lowering Transition Energy in the SPS optics, injection, resonance, lattice 619
 
  • H. Bartosik, G. Arduini, Y. Papaphilippou
    CERN, Geneva, Switzerland
 
  Beam stability for high intensity LHC beams in the SPS can be improved by increasing the slippage factor, i.e. reducing the transition energy. In this paper, possible ways of modifying the optics of the SPS for lower transition energy are reviewed. In particular, a threefold increase of the slippage factor at injection can be achieved by decreasing the integer part of the tunes by 6 units. The properties of this new low-transition optics are compared with the nominal SPS optics, including working point and resonance behavior. Possible limitations are discussed.  
 
MOPS014 Tune and Space Charge Studies for High-brightness and High-intensity Beams at CERN PS resonance, space-charge, injection, beam-losses 625
 
  • S.S. Gilardoni, S. Aumon, J. Brenas, P. Freyermuth, A. Huschauer, R. Maillet, E. Matli, R.R. Steerenberg, B. Vandorpe
    CERN, Geneva, Switzerland
  • E. Benedetto
    National Technical University of Athens, Zografou, Greece
 
  The current 1.4 GeV CERN PS injection energy limits the maximum intensity required by the future High-Luminosity LHC. The bare-machine large chromaticity combined with the non-linear space charge forces make high-brightness and high-intensity beams crossing betatron resonances along the injection flat bottom, inducing transverse emittance blow-up and beam losses. A scan of the working point plane {Qx,Qy} was done in order to identify beam destructive resonances, in the framework of a possible 2 GeV injection energy upgrade which would reduce the space charge effect on the tune. Experiments were carried out in order to review the maximum space charge tune shift for which no transverse emittance blow-up is observed. The results of measurements and simulations will be presented in this paper.  
 
MOPS018 Simulation and Measurement of Half Integer Resonance in Coasting Beams on the ISIS Ring resonance, simulation, injection, space-charge 637
 
  • C.M. Warsop
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • D.J. Adams, B. Jones, B.G. Pine, H. V. Smith, R.E. Williamson
    STFC/RAL/ISIS, Chilton, Didcot, Oxon, United Kingdom
 
  ISIS is the spallation neutron source at the Rutherford Appleton Laboratory in the UK. Operation centres on an 800 MeV rapid cycling synchrotron (RCS), which provides 3·1013 protons per pulse at 50 Hz, corresponding to a beam power of 0.2 MW. In common with many lower energy, high intensity proton rings, a key loss mechanism on ISIS is half integer resonance under space charge. This paper summarises experimental and simulation work studying half integer resonance in a “2D” coasting beam in the ISIS ring: understanding this is an essential prerequisite for explaining the more complicated case of RCS operation. For coasting beam experiments, the ring is reconfigured to storage ring mode with RF off and main magnets powered on DC current only. A 70 MeV beam is injected, painted appropriately, and manipulated so as to approach resonance. Understanding how the resonant condition develops is central to explaining observations, so realistic simulations of resonance, including injection, ramping of intensity and tunes are being developed. Results from the ORBIT code are presented and compared with experimental and theoretical results. Finally, future plans are summarized.  
 
MOPS023 An Analytical Lagrangian Model for Analyzing Temperature Effects in Intense Non-neutral Beams* simulation, focusing, controls, space-charge 646
 
  • E.G. Souza, A. Endler, R. Pakter, F.B. Rizzato
    IF-UFRGS, Porto Alegre, Brazil
 
  High-intensity charged-particle beams are used in several areas of physics. We can mention as an illustration, high-energy colliders, particle accelerators and vacuum electron devices. In all cases quoted above, the beam lose particles in the acceleration process, between its production to its fi nal destination. These ejected particles, generally, produce a surrounding structure around the beam core, called halo. This undesirable structure is seen in simulation as well as in actual linacs, and its formation has been one of the main sources of energy loss in the acceleration devices. For this reason, the need for an advance in understand the mechanism that produce the halo becomes necessary. In view of the whole problem, we contruct a 1D Lagrangian warm-fluid model for describe the behavior of inhomogeneous charged-particle beam in solenoidal focusing magnetic field. The equations of motion are derived for an adiabatic process with a state equation originated from the ideal gas law. In the end, the model is compared with self-consistent simulation and is used to explain emittance growth and jets of particle, even when the system is out of equilibrium.  
 
MOPS025 Studies of Emittance Measurement by Quadrupole Variation for the IFMIF-EVEDA High Space Charge Beam quadrupole, space-charge, simulation, beam-transport 652
 
  • P.A.P. Nghiem, E. Counienc
    CEA/DSM/IRFU, France
  • N. Chauvin
    CEA/IRFU, Gif-sur-Yvette, France
  • C. Oliver
    CIEMAT, Madrid, Spain
 
  For the high-power (1 MW) beam of the IFMIF-EVEDA prototype accelerator, emittance measurements at nearly full power are only possible in a non-interceptive way. The method of quadrupole variation is explored here. Due to the high space charge regime, beam transport is strongly non-linear, and the classical matrix inversion is no more relevant. Inverse calculations using a multiparticle code is mandatory. In this paper, such emittance measurements are studied, aiming at checking its feasibility and evaluating its precision, taking into account the constraints of losses and quadrupole limitations.  
 
MOPS027 Stability Charts for the IFMIF SRF-Linac linac, resonance, SRF, space-charge 658
 
  • W. Simeoni, N. Chauvin
    CEA/IRFU, Gif-sur-Yvette, France
  • A. Mosnier, P.A.P. Nghiem, D. Uriot
    CEA/DSM/IRFU, France
 
  Among the most recent projects, the IFMIF-EVEDA accelerators break the record of high intensity, leading to a multi-MW beam power at relatively low energy. The concern for such accelerated beams is the predominance of the self-field energy upon the beam energy. In these conditions, the space charge effect is at its maximum, which triggers different nonlinear mechanisms implying emittance growth, halo formation and sudden particle lost. In this proceeding we show the stability charts constructed for the IFMIF SRF-Linac, with which are identified the collective space charge resonances responsible of transverse-longitudinal emittance exchange and emittance growth.  
 
MOPS028 An Ion Beam Matching to a Linac Accelerating-focusing Channel rfq, linac, ion, simulation 661
 
  • A. Orzhekhovskaya, W.A. Barth, G. Clemente, L.A. Dahl, P. Gerhard, L. Groening, M. Kaiser, M.T. Maier, S. Mickat, B. Schlitt, H. Vormann, S.G. Yaramyshev
    GSI, Darmstadt, Germany
  • U. Ratzinger
    IAP, Frankfurt am Main, Germany
 
  Funding: Work supported by HIC for FAIR
A modern linear accelerator of ions is a long chain of different accelerating-focusing structures. The design of new linacs, as well as an upgrade and optimization of operating facilities, requires precise and reliable beam matching with the subsequent sections. Proper matching of the beam to the channel allows to improve the performance of the whole linac and to reduce the specific costs. Additionally it helps to avoide particle loss in high energy high intensity linacs. Generally a matching algorithm combines precisely measured or calculated accelerating-focusing external fields and experimentally obtained details of the beam parameters with an advanced code for beam dynamics simulations including space charge effects. Experimental results are introduced into a code as input data. The described algorithm has already been successfully implemented for several GSI projects: an upgrade of the GSI heavy ion linac UNILAC, an ion linac for the cancer therapy, the proton linac for the FAIR facility, a facility for laser acceleration of ions and others. Measured data and results of beam dynamics simulations leading to an achieved improvement of the linac performance are presented.
 
 
MOPS031 Beam Dynamics Redesign of IFMIF-EVEDA RFQ for a Larger Input Beam Acceptance rfq, focusing, solenoid, optics 670
 
  • M. Comunian, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
 
  For the IFMIF-EVEDA RFQ, a very challenging project of a deuteron CW RFQ at 175 MHz from 0.1 MeV to 5 MeV with 125 mA of current, the input beam characteristics are very important. A lower focusing force in the first part of the RFQ as beam implemented in order to reduce the requirements of the input beam. In the article a full description of the new design will be reported with the changes in the RFQ performances.  
 
MOPS034 Progress on Space Charge Compensation Study in Low Energy High Intense H+ Beam* electron, injection, ion, space-charge 676
 
  • P.N. Lu, Z.Y. Guo, S.X. Peng, Z.X. Yuan, J. Zhao
    PKU/IHIP, Beijing, People's Republic of China
  • H.T. Ren
    Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China
 
  This article lays emphasis on the relationship between the Space Charge Compensation (SCC) and the beam quality in different conditions. Ar and Kr are used to compensate a 35keV/90mA H+ beam with the gas pressure from 3.7×10-4 Pa to 6×10-3 Pa. Experiments are conducted in different compensation states with three approaches. With an energy spectrometer, we have got the energy spectra of Extra Compensation Gas Ions (ECGI). By a beam profile meter, the beam profiles are obtained when the injection of compensation gas is gradually rising. In the meantime, the beam emittance is measured under different compensation conditions. After measurements of the above data, the potential and the rest charge distributions in the beam are calculated by analyzing the ECGI energy spectra and beam profiles. All experiments performed aimed to seek out the best circumstance for SCC dominated low energy high intensity ion beams.together to calculate the potential distribution are calculated by analyzing the energy spectra and beam profiles. All experiments performed aimed to seeking for the best circumstances in SCC dominated low energy high intensity ion beams.  
 
MOPS039 High Power Proton Linac Front-End: Beam Dynamics Investigation and Plans for the ESS rfq, solenoid, injection, proton 688
 
  • A. Ponton
    ESS, Lund, Sweden
 
  Beam availibility is one of the major concerns for the designer of high power proton linacs. Since the Radio-Frequency Quadrupole (RFQ) will shape and accelerate the beam in the early stage of its propagation it will have a significant impact on the particle dynamics throughout the rest of the linac. The key role of the RFQ is consequently to deliver high quality beams with optimal transmission. Furthermore understanding the space charge compensation mechanism in the Low Energy Beam Transport line (LEBT) is mandatory if one wants to perform calculations with realistic beams. The European Spallation Source (ESS) has put important R&D efforts in designing the linac front-end and deep beam dynamics studies have been undertaken. Results of the investigation work will be presented. We will then deal with the future plans for the ESS and we will finally give a full description of the RFQ and LEBT scheme.  
 
MOPS042 One-Dimensional Adiabatic Child-Langmuir Flow simulation, electron, gun, plasma 694
 
  • C. Chen
    MIT, Cambridge, Massachusetts, USA
  • R. Pakter, F.B. Rizzato
    IF-UFRGS, Porto Alegre, Brazil
 
  Funding: Research supported in part by US Department of Energy, Grant No. DE-FG02-95ER40919, CNPq, FAPERGS, INCTFCx of Brazil, and US Air Force Office of Scientific Research, Grant No. FA9550-09-1-0283.
A theory is presented that describes steady-state one-dimensional Child-Langmuir flow at a self-consistent finite temperature distribution. In particular, warm-fluid equations and adiabatic equation of state are used to derive the self-consistent Poisson equation. The profiles of the charged-particle density, the velocity, the electrostatic potential, the pressure and the temperature are computed. Results are compared with self-consistent simulations.
 
 
MOPS043 Beam Performance in H Injector of LANSCE simulation, space-charge, beam-transport, ion-source 697
 
  • Y.K. Batygin, C. Pillai, L. Rybarcyk
    LANL, Los Alamos, New Mexico, USA
 
  During beam development time in 2010 we performed a series of beam emittance and beam profile scans along 750-keV H beam transport and 800-MeV linac. The purpose of the measurements was to determine the effects of space charge, slow-wave intensity modulation or chopping, RF buncher fields, and vacuum conditions on beam performance. As previously reported*, from our observation and analysis we concluded that the 750 keV H beam transport is space-charge uncompensated. This presentation will look at the relative importance of space-charge, chopping, and RF-buncher on the observed emittance growth for beam in the short and long pulse regime as well as the effects of beam line vacuum degradation on beam size and emittance at the end of the linac.
* Y. Batygin et al., “Space-charge effects in H Low-Energy Beam Transport of LANSCE,” to be published in Proc. of the 2011 Particle Accelerator Conference, March 28-April 1, 2011, New York, NY.
 
 
MOPS047 Studies of Transverse Single-pass Beam Breakup in E-Linac HOM, cavity, linac, dipole 706
 
  • D. Kaltchev, R.A. Baartman, Y.-C. Chao, P. Kolb, S.R. Koscielniak, L. Merminga, A.K. Mitra, V. Zvyagintsev
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
 
  Time-domain simulations of single-pass transverse beam-breakup (BBU) effects in E-linac are described. We use dipole-HOM parameters for the 9-cell cavity obtained with Particle Studio to evaluate the rms bunch orbit offsets at linac exit. Finding the multi-bunch orbit contribution to machine emittance as a function of the average beam current allows to evaluate the performance of two cavity models for two different modes of machine operation.  
 
MOPS050 Electron Beam Dynamics in the 50 MeV ThomX Compact Storage Ring electron, scattering, photon, collective-effects 715
 
  • C. Bruni, J. Haissinski
    LAL, Orsay, France
  • A. Loulergue, R. Nagaoka
    SOLEIL, Gif-sur-Yvette, France
 
  ThomX is a high flux compact X-ray source based on Compton back scattering between a relativistic electron beam and an intense laser pulse. To increase the repetition rate, the electron beam is stored in a ring. The main drawback of such a scheme is the low energy of the electrons regarding collective effects and intrabeam scattering. These effects tend to enlarge or even disrupt the stored bunch and they limit its charge, especially in a system where damping plays a negligible role. Thus such collective effects reduce the maximum X-ray flux and it is important to investigate them to predict the performance of this type of X-ray source. In addition, the Compton back scattering acts on the electron beam by increasing its energy spread. This presentation will show firstly the impact of collective effects on the electron beam, essentially during the first turns when they are the most harmful. Then, the reduction of the X-ray flux due to Compton back scattering and intrabeam scattering will be investigated on a longer time scale.  
 
MOPS055 Observation of Intensity Dependent Single Bunch Effects at the Synchrotron Light Source PETRA III impedance, synchrotron, single-bunch, electron 730
 
  • R. Wanzenberg, K. Balewski
    DESY, Hamburg, Germany
 
  At DESY the PETRA ring is operated as a synchrotron radiation facility with a very low emittance of 1 nm. Regular user operation has started in summer 2010. A summary of observations and measurements of intensity dependent single bunch effects is presented in this report. The longitudinal impedance of the ring is estimated from the measured bunch length versus beam intensity. The results are compared with predictions from the impedance model. Furthermore measurements of the single bunch intensity limit due to the transverse mode coupling instability (TMCI) are reported. The tune and phase shift around the ring has been measured as a function of the beam intensity. At PETRA III tune spectra have been observed with some characteristics which have been observed at other storage rings in connection with electron cloud effects. The present status of the observations of potential electron cloud effects is also discussed.  
 
MOPS058 KEKB Linac Wakefield Studies of Comparing Theoretical Calculation, Simulation and Experimental Measurement* wakefield, linac, injection, simulation 739
 
  • L. Zang, N. Iida, Y. Ogawa, M. Satoh, M. Yoshida, D.M. Zhou
    KEK, Ibaraki, Japan
 
  For superKEKB, in order to achieve aiming luminosity machine need to run with a nano-beam scheme so that a small beam emittance is critical important. During the beam propagation, the short-range wake field in the accelerating structure will cause the beam instability and emittance growth. In practical, injecting beam with certain offset could compensate wakfield. And beam emittance could be measured by tuning the quadruple known as quadscan method. In this paper, wakefield theoretical calculation, simulation results will be presented. And then the wakefield impact to beam emittance and wakefield compensation will be discussed. Finally, we will show the comparison of the results getting from theoretical calculation and experimental measurement.  
 
MOPS069 Review of Beam Instabilities in the Presence of Electron Clouds in the LHC electron, injection, simulation, luminosity 760
 
  • K.S.B. Li, G. Rumolo
    CERN, Geneva, Switzerland
 
  Recent observations at the LHC indicate the build-up of electron clouds when 50 ns spaced beams are injected into the machine at nominal intensity. These electron clouds are a source of coherent beam instabilities and incoherent emittance growth and limit the achievable luminosity. To better understand the influence of electron clouds on the beam dynamics, simulations have been carried out to study both the coherent and the incoherent effects on the beam. The simulations are performed with the HeadTail tracking code; the usage of new post-processing software allows determining not only the beam intensity thresholds in terms of the central electron cloud density but also the footprint of the beam in tune space. In this paper we review instability thresholds and tune footprints for beams with different emittances and interacting with an electron cloud in field-free or dipole regions.  
 
MOPS074 Stabilization of the LHC Single-bunch Transverse Instability at High-energy by Landau Octupoles octupole, simulation, beam-losses, single-bunch 775
 
  • E. Métral, B. Salvant
    CERN, Geneva, Switzerland
  • N. Mounet
    EPFL, Lausanne, Switzerland
 
  When the first ramp was tried on Saturday 15/05/2010 with a single bunch of about nominal intensity (i.e. ~ 1011 p/b), the bunch became unstable in the horizontal plane at ~ 2 TeV. The three main observations were: (i) a “Christmas tree” in the transverse tune measurement application (with many synchrotron sidebands excited), (ii) beam losses (few tens of percents) in IR7, and (iii) an increase of the bunch length. This transverse coherent instability has been stabilized successfully with Landau octupoles. Comparing all the measurements performed during this first year of LHC commissioning with the theoretical and simulation predictions reveals a good agreement.  
 
MOPS086 Beam Breakup Simulation for the PEP-X ERL HOM, cavity, simulation, recirculation 805
 
  • Y. Jiao, Y. Cai, A. Chao
    SLAC, Menlo Park, California, USA
 
  Funding: The work is supported by the U.S. Department of Energy under contract No. DE-AC02-76SF00515.
The transverse beam breakup (BBU) is one of the dominant factors in ERL for the available beam current. A tracking code built in Matlab is developed and benchmarked by comparing with the analytical solutions with the simple model. Study on the threshold current and emittance growth due to the transverse BBU for PEP-X ERL are presented in this paper.
 
 
MOPS088 Simulation of Electron Cloud Beam Dynamics for CesrTA simulation, electron, betatron, positron 808
 
  • K.G. Sonnad, G. Dugan, M.A. Palmer, G. Ramirez, H.A. Williams
    CLASSE, Ithaca, New York, USA
  • K.R. Butler
    Cornell University, Ithaca, New York, USA
  • M.T.F. Pivi
    SLAC, Menlo Park, California, USA
 
  This presentation provides a comprehensive set of results obtained using the simulation program CMAD. CMAD is being used for studying electron cloud induced beam dynamics issues for CesrTA, which is a test facility for studying physics associated with electron and positron damping rings. In particular, we take a closer look at electron cloud induced effects on positron beams, including head-tail motion, emittance growth and incoherent tune shifts for parameters specific to ongoing experimental studies at CesrTA. The correspondence between simulation and experimental results will also be discussed.
Work supported by US Department of Energy grant number DE-FC02-08ER41538
and the National Science Foundation grant number PHY-0734867
 
 
MOPS090 Observation of Beam Ion Instability in SPEAR3 ion, vacuum, single-bunch, quadrupole 814
 
  • L. Wang, Y. Cai, W.J. Corbett, T.O. Raubenheimer, J.A. Safranek, J.F. Schmerge, J.J. Sebek
    SLAC, Menlo Park, California, USA
  • D. Teytelman
    Dimtel, San Jose, USA
 
  Weak vertical coupled bunch instability with oscillation amplitude at μm level has been observed in SPEAR3. The instability becomes stronger when there is a vacuum pressure rise by partially turning off vacuum pumps and it becomes weaker when the vertical beam emittance is increased by turning off the skew quadrupole magnets. These confirmed that the instability was driven by ions in the vacuum. The threshold of the beam ion instability when running with a single bunch train is just under 200 mA. This paper presents the comprehensive observations of the beam ion instability in SPEAR3. The effects of vacuum pressure, beam current, beam filling pattern, chromaticity, beam emittance and bunch-by-bunch feedback are investigated in great detail.pattern, chromaticity, beam emittance and bunch-by-bunch feedback are investigated in great detail.  
 
MOPS091 Study of Electron Cloud for MEIC electron, simulation, luminosity, dipole 817
 
  • S. Ahmed, J.D. Dolph, G.A. Krafft, T. Satogata, B.C. Yunn
    JLAB, Newport News, Virginia, USA
 
  Funding: Authored by Jefferson Science Associates, LLC under U.S. DOE Contract No. DE-AC05-06OR23177.
The Medium Energy Electron Ion Collider (MEIC) at Jefferson Lab has been envisioned as a future high energy particle accelerator beyond the 12 GeV upgrade of the existing Continuous Electron Beam Accelerator Facility (CEBAF). Synchrotron radiation from the closely spaced proton bunches in MEIC can generate photoelectrons inside the vacuum chamber and cause secondary emission due to multipacting in the presence of beam's electric field. This phenomenon can lead to fast build up of electron density, known as electron cloud effect – resulting into beam instability coupled to multi-bunches in addition to a single bunch. For MEIC, the estimated threshold value of the electron-cloud density is approximately 5 x 1012 m-3. In this paper, we would like to report the self-consistent simulation studies of electron cloud formation for MEIC. The code has been benchmarked against the published data of electron cloud effects observed in LHC. Our first simulations predict increase of electron clouds with the increase of repetition rate. The detailed simulations are under progress and will be reported.
 
 
MOPZ002 MICE Beamline dipole, solenoid, beam-losses, target 823
 
  • Y. Karadzhov
    DPNC, Genève, Switzerland
 
  The muon ionization cooling experiment (MICE) is under development at the Rutherford Appleton Laboratory (UK). The goal of the experiment is to build a section of a muon cooling channel that can demonstrate the principle of Ionization cooling over a range of emittances and momenta. The MICE beam line must generate several matched muon beams with different momenta and optical parameters at the entrance of the cooling channel. This is done exploiting a titanium target dipping into the ISIS proton beam, a 5T superconducting pion decay solenoid, two dipole magnets and a mech­a­nism for in­flation of the ini­tial emit­tance called diffuser. First mea­sure­ments of muon rates and beam emit­tance per­formed using two TOF hodoscopes detectors will be presented.  
 
MOPZ013 MAUS: MICE Analysis User Software simulation, controls, extraction, factory 850
 
  • C.D. Tunnell
    JAI, Oxford, United Kingdom
  • C.T. Rogers
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
 
  The Muon Ionization Cooling Experiment (MICE) is unique because it measures accelerator physics quantities using particle physics methods. It follows that the software that forms the theoretical model of MICE needs to be able to not only propagate beam envelopes and optical parameters but also model detector responses and matter effects for cooling. MICE addresses this dichotomy with the software framework MAUS in order to maximize its physics sensitivity whilst providing the conveniences of, for example, a common data structure. The diversity of challenges that MICE provides from the analysis perspective means that appropriately defining the software scope and layout is critical to the correctness and maintainability of the final accelerator physics analyses. MICE has structured its code into a Map-Reduce framework to enable better parallelization whilst also introducing unit, functional, and integration tests to ensure code reliability and correctness. These methods can apply to other experiments.  
 
MOPZ016 MICE Step I: First Measurement of Emittance with Particle Physics Detectors* simulation, quadrupole, collider, factory 853
 
  • L. Coney
    UCR, Riverside, California, USA
  • M. Popovic
    Fermilab, Batavia, USA
  • M.A. Rayner
    DPNC, Genève, Switzerland
 
  The muon ionization cooling experiment (MICE) is a strategic R&D project intending to demonstrate the only practical solution to prepare high brilliance beams necessary for a neutrino factory or muon colliders. MICE is under development at the Rutherford Appleton Laboratory (UK). It comprises a dedicated beam line to generate a range of input emittance and momentum, with time-of-flight and Cherenkov detectors to ensure a pure muon beam. The emittance of the incoming beam is measured in the upstream magnetic spectrometer with a sci-fiber tracker. A cooling cell will then follow, alternating energy loss in Li-H absorbers and RF acceleration. A second spectrometer identical to the first and a second muon identification system measure the outgoing emittance. In the 2010 run the beam and most detectors have been fully commissioned and a first measurement of the emittance of a beam with particle physics (time-of-flight) detectors has been performed. The analysis of these data should be completed by the time of the Conference. The next steps of more precise measurements, of emittance and emittance reduction (cooling), that will follow in 2011 and later, will also be outlined.
Abstract is submitted by the MICE Speakers Bureau.
If accepted, most likely Dr. Kaplan will present it.
As a first result in a novel sector, we propose it for an oral presentation
 
 
MOPZ024 Muon Ionization Cooling Experiment: Controls and Monitoring EPICS, controls, monitoring, target 856
 
  • P.M. Hanlet
    IIT, Chicago, Illinois, USA
  • C.N. Booth
    Sheffield University, Sheffield, United Kingdom
 
  Funding: NSF PHY0842798
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 and Data monitoring systems. A description of this system, its implementation, and performance during recent muon beam data collection will be discussed.
For the MICE collaboration.
 
 
MOPZ028 Solid Absorber Program Status for MICE Step IV status, simulation, insertion, cavity 859
 
  • P. Snopok
    IIT, Chicago, Illinois, USA
  • J.H. Cobb
    JAI, Oxford, United Kingdom
  • G.T. Kafka
    Illinois Institute of Technology, Chicago, Illinois, USA
  • C.T. Rogers
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
 
  Funding: Work is supported by the Science and Technology Facilities Council and the U.S. Department of Energy.
In the Muon Ionization Cooling Experiment (MICE), muons are cooled by passing through material and then through RF cavities to compensate for the energy loss, which reduces the transverse emittance. In addition to demonstrating the transverse emittance reduction using flat solid absorbers, it is also planned to demonstrate longitudinal emittance reduction via emittance exchange in MICE by using a solid wedge-shaped absorber in MICE Step IV. The current status of the simulation and design effort for both flat and wedge-shaped solid absorbers is summarized.
 
 
MOPZ034 Proton Contamination Studies in the MICE Muon Beam Line proton, lattice, quadrupole, positron 871
 
  • S.D. Blot, Y.K. Kim
    University of Chicago, Chicago, Illinois, USA
  • R.R.M. Fletcher
    UCR, Riverside, California, USA
  • D.M. Kaplan
    Illinois Institute of Technology, Chicago, Illinois, USA
  • C.T. Rogers
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
 
  The Muon Ionization Cooling Experiment (MICE) aims to demonstrate transverse beam emittance reduction for a muon beam. To create these muons, a titanium target is dipped into the ISIS proton accelerator at Rutherford Appleton Laboratory (UK) to create pions, which are transported and decay to muons in the MICE beamline. Beam particle identification and triggering is performed using time of flight (ToF) detectors. When running the MICE beamline with positive polarity, protons produced in the target contaminate the muon beam with a sufficiently high rate to saturate the TOF detectors. Polyethylene sheets of varying thicknesses were installed to absorb the proton impurities in the beam. Studies with pion beams at momenta of 140, 200, and 240MeV/c were performed with different proton absorber thicknesses. The results of these studies show good agreement with theoretical range plots and will be presented.  
 
MOPZ036 Ionization Cooling in MICE Step IV scattering, simulation, solenoid, factory 877
 
  • T. Carlisle, J.H. Cobb
    JAI, Oxford, United Kingdom
  • R.R.M. Fletcher
    UCR, Riverside, California, USA
 
  The international Muon Ionization Cooling Experiment (MICE), under construction at RAL, will test and characterize a prototype cooling channel for a future Neutrino Factory or Muon Collider. The cooling channel aims to achieve, using liquid hydrogen absorbers, a 10% reduction in transverse emittance. The change in 4D emittance will be determined with a relative accuracy of 1% by measuring muons individually. These include two scintillating fibre trackers embedded within 4 T solenoid fields, TOF counters and a muon ranger. Step IV of MICE will begin in 2012, producing the experiment's first precise emittance-reduction measurements. Multiple scattering in candidate Step IV absorber materials was studied in G4MICE, based on GEANT4. Equilibrium emittances for low-Z materials from hydrogen to aluminium can be studied experimentally in Step IV of MICE, and compared with simulations.  
 
TUODA01 Vertical Emittance Reduction and Preservation at the ESRF Electron Storage Ring coupling, quadrupole, feedback, storage-ring 928
 
  • A. Franchi, J. Chavanne, F. Ewald, L. Farvacque, T.P. Perron, K.B. Scheidt
    ESRF, Grenoble, France
 
  In 2010 a campaign for the reduction and preservation of low vertical emittance at the ESRF electron storage ring was undertaken: values between 20 and 30 pm have been dramatically reduced to 3.5-4.5 pm, even during beam delivery. This improvement is the result of an increased measurement precision provided by the recently upgraded beam position monitoring system, a new correction algorithm, a larger number of correctors and two independent schemes for the automatic compensation of coupling induced by a few insertion devices whenever their gaps are moved by users during beam delivery. This paper summarizes the campaign's milestones and the results updated to the first half of 2011.  
slides icon Slides TUODA01 [5.297 MB]  
 
TUODA02 Status of Sirius – a New Brazilian Synchrotron Light Source dipole, permanent-magnet, lattice, synchrotron 931
 
  • L. Liu, R. Basílio, J.F. Citadini, R.H.A. Farias, R.J.F. Marcondes, X.R. Resende, F. Rodrigues, A.R.D. Rodrigues, P.P. Sanchez, R.M. Seraphim, G. Tosin, F. H. de Sá
    LNLS, Campinas, Brazil
 
  We present an overview of the new synchrotron light source project Sirius, currently being designed at the Brazilian Synchrotron Light Laboratory (LNLS) in Campinas, São Paulo. Sirius will consist of a 480 m circumference, 3.0 GeV, 20 TBA cells, 1.7 nm.rad emittance storage ring. The dipoles will be based on the use of permanent magnet technology and will combine low field magnets (0.5 T) for the main beam deflection with a short slice of high field magnet (2.0 T) to generate photons of 12 keV critical energy with modest total energy loss. There will be 18 straight sections for insertion devices. In this report we describe the current status for the magnet lattice design and some of the subsystems.  
slides icon Slides TUODA02 [2.434 MB]  
 
TUXB01 Methods and Tools to Simulate and Analyse Non-linear Dynamics in Electron Storage Rings storage-ring, lattice, sextupole, quadrupole 937
 
  • L.S. Nadolski
    SOLEIL, Gif-sur-Yvette, France
 
  This talk will present the different approaches and tools that have been recently developed while trying to understand or predict the non-linear dynamics of electron storage rings. Different algorithms have been recently used at different places to optimize the sextupole tunings, while the refinement of the models of existing machines together with more accurate measurement techniques enable now to fully understand the limitations of such facilities specially in the presence of insertion devices.  
slides icon Slides TUXB01 [7.624 MB]  
 
TUOAB01 Lattice Design of a Very Low-emittance Storage Ring for SPring-8-II lattice, dynamic-aperture, alignment, resonance 942
 
  • Y. Shimosaki, K.K. Kaneki, T. Nakamura, H. Ohkuma, J. Schimizu, K. Soutome, M. Takao
    JASRI/SPring-8, Hyogo-ken, Japan
 
  The design work for an upgrade project of the SPring-8, the SPring-8-II, is in progress. Its ultimate goal is to provide a superior brilliance of photons by reducing emittance of electrons until a diffraction limit. A multi-bend lattice has been adopted for the emittance reduction; a double-bend lattice (natural emittance of 2000 pmrad at 6 GeV), a triple-bend lattice (400 pmrad) and a quadruple-bend lattice (170 pmrad) were designed step by step for studying its feasibility*. For an additional emittance reduction, beam dynamic issues for a sextuple-bend lattice have been examined for the first candidate. In this case, the natural emittance is about 70 pmrad. The dynamic aperture has been enlarged by studying beam dynamic phenomena caused by nonlinear dispersion, nonlinear chromaticity, nonlinear resonance, etc., and by optimizing linear and nonlinear optics. The lattice design for the coming upgrade of SPring-8 will be presented in detail.
* K. Soutome et al., "Design Study of a very Low-emittance Storage Ring for the Future Upgrade Plan of SPring-8", Proc. of IPAC10, WEPEA032, p. 2555 (2010).
 
slides icon Slides TUOAB01 [4.812 MB]  
 
TUYB02 The Challenges of Ultra-low Emittance Damping Rings damping, electron, quadrupole, coupling 956
 
  • D. L. Rubin
    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.
In this paper we review the state of the art of the design of damping rings for linear colliders, as supported by the experimental data from ATF and CESR test damping rings. We consider implications of measurements of electron cloud dynamics and mitigation in a radiation dominated ring. The techniques developed for tuning for ultra-low emittance in these rings are summarized. Other dynamics manifested in the ultra-low emittance regime where collective effects are important are discussed.
 
slides icon Slides TUYB02 [7.198 MB]  
 
TUYB03 CLIC Conceptual Design and CTF3 Results linac, target, damping, luminosity 961
 
  • D. Schulte
    CERN, Geneva, Switzerland
 
  An international collaboration is carrying out an extensive R&D programme to prepare CLIC, a multi-TeV electron-positron collider. In this concept, the colliding beams will be accelerated in very high gradient normal conducting 12 GHz accelerating structures. The necessary RF power is extracted from a high-current, low-energy drive beam that runs parallel to the colliding beams and is generated in a central complex. This year the collaboration will produce a conceptual design report to establish the feasibility of the technology. The CLIC concept will be introduced and the status of key studies of critical issues will be reviewed. A focus will be on the CLIC Test Facility 3 (CTF3), which is a test facility to produce and use high current a drive beam.  
slides icon Slides TUYB03 [13.204 MB]  
 
TUPC004 The Luminosity for the ILC Travelling Focus Regime with Offsets and Angle Scans* luminosity, simulation, collider, wakefield 991
 
  • L.I. Malysheva, O.S. Adeyemi, V.S. Kovalenko, A. Ushakov
    University of Hamburg, Hamburg, Germany
  • K. Buesser, A.F. Hartin, G.A. Moortgat-Pick, N.J. Walker
    DESY, Hamburg, Germany
  • S. Riemann, F. Staufenbiel
    DESY Zeuthen, Zeuthen, Germany
 
  One of the crucial challenges of a future linear collider is to provide high luminosity. In the current ILC design a luminosity of 2x1034 is foreseen. In order to enhance the luminosity, use of the “travelling focus” scheme is under discussion. Within this regime the hourglass effect at the interaction point can be effectively overcome by judiciously arranging for the head and tail of the bunches to be focused at a proportionally displaced longitudinal position. The effect is further enhanced by the strong beam-beam interaction which continuously focuses the bunches during collision. In principle travelling focus could provide an additional 30% luminosity. Nevertheless the regime is highly sensitive to beam-beam transverse and angular offsets at the collision point. The study of the luminosity stability for various ILC parameters using traveling focus will be presented.  
 
TUPC020 Alignment and Wake Field Issues in the CLIC RTML linac, lattice, wakefield, cavity 1039
 
  • F. Stulle, S. Döbert, A. Latina, D. Schulte
    CERN, Geneva, Switzerland
 
  At main linac injection the particle beams need to stay within tight tolerances for the transverse emittances and the pointing stability. We study how these tolerances influence alignment requirements for the RTML components and the stability of the beams entering the RTML. An emphasize is put on the booster linac and the RF cavities of the second bunch compression stage since short and long range wake fields might strongly influence beam dynamics in these parts of the RTML.  
 
TUPC022 Design of the CLIC Drive Beam Recombination Complex linac, injection, sextupole, synchrotron 1045
 
  • J. Barranco, P.K. Skowroński, F. Tecker
    CERN, Geneva, Switzerland
  • C. Biscari
    INFN/LNF, Frascati (Roma), Italy
 
  The CLIC Drive Beam Recombination Complex (DBRC) is designed to compress beam pulses from a current of 4.1 A to 100 A before using them to produce RF power in the deceleration lines. The beam is transported isochronously through a complex system consisting of a delay loop, two combiner rings and final turn around. The system is designed to preserve transverse and longitudinal emittances. During the optics design, chromaticity and non-linear dispersion were identified as the main single particle dynamics causes for transverse emittance increase. Different sextupole families are used to compensate these chromatic effects while keeping isochronicity. The bunch length is also adjusted to minimize coherent synchrotron radiation effects on bunch length, energy spread and transverse emittance. Finally, the injection scheme of the combiner rings was improved making the time variable bump created with help of the RF deflectors truly achromatic.  
 
TUPC030 Recommendation for Mitigations of the Electron Cloud Instability in the ILC electron, vacuum, positron, quadrupole 1063
 
  • M.T.F. Pivi, L. Wang
    SLAC, Menlo Park, California, USA
  • L.E. Boon, K.C. Harkay
    ANL, Argonne, USA
  • J.A. Crittenden, G. Dugan, M.A. Palmer
    CLASSE, Ithaca, New York, USA
  • T. Demma, S. Guiducci
    INFN/LNF, Frascati (Roma), Italy
  • M.A. Furman
    LBNL, Berkeley, California, USA
  • K. Ohmi, K. Shibata, Y. Suetsugu, J. Urakawa
    KEK, Ibaraki, Japan
  • C. Yin Vallgren
    Chalmers University of Technology, Chalmers Tekniska Högskola, Gothenburg, Sweden
 
  Funding: Work supported by the Director, Office of Science, High Energy Physics, U.S. DOE under Contract No. DE-AC02-76SF00515.
Electron cloud has been identified as one of the highest priority issues for the ILC Damping Rings (DR). A working group has evaluated the electron cloud effect and instability, and mitigation solutions for the electron cloud formation. Working group deliverables include recommendations for the baseline and alternate solutions for the electron cloud mitigation in various regions of the ILC Positron DR, which is presently assumed to be the 3.2km design. Detailed studies of a range of mitigation options including coatings, clearing electrodes, grooves and novel concepts, were carried out over the previous several years by nearly 50 researchers, and the results of the studies form the basis for the recommendation. The assessments of the benefits or risks associated with the various options were based on a systematic ranking scheme. The recommendations are the result of the working group discussions held at numerous meetings and during a dedicated workshop. The mitigation choices will be also presented in a more detailed report later in 2012. In addition, a number of items requiring further investigation were identified and studies will be carried out at CesrTA and other institutions.
 
 
TUPC031 Advanced Research Electron Accelerator Laboratory Based on Photocathode RF Gun gun, electron, laser, controls 1066
 
  • B. Grigoryan, G.A. Amatuni, V.S. Avagyan, A. Grigoryan, M. Ivanyan, V.G. Khachatryan, E.M. Laziev, K. Manukyan, I.N. Margaryan, V. Sahakyan, A. Sargsyan, A. Tarloyan, A.V. Tsakanian, V.M. Tsakanov, A. Vardanyan
    CANDLE, Yerevan, Armenia
  • T. Vardanyan
    YSU, Yerevan, Armenia
 
  The low energy sub-picosecond duration electron bunches with extremely small beam emittance have wide applications in advanced research of new accelerator concepts, radiation physics, time-resolved pulse radiolysis and electron diffraction. The conceptual design and experimental program of the Advanced Research Electron Accelerator Laboratory (AREAL) at CANDLE based on photocathode RF gun are presented. The AREAL design implies single and multibunch operation modes with variable beam energy of 5-20 MeV and 10-100 pC bunch charge. The design is based on 3 GHz 1.6 cells RF gun followed by S-Band accelerating linac.  
 
TUPC032 Beam Phase-Space Study for AREAL RF Photogun Linac gun, space-charge, electron, linac 1069
 
  • B. Grigoryan, G.A. Amatuni, I.N. Margaryan, A.V. Tsakanian, V.M. Tsakanov, A. Vardanyan
    CANDLE, Yerevan, Armenia
 
  In order to produce high brightness electron beams with sub-picosecond bunch duration, the creation of Advanced Research Electron Accelerator Laboratory (AREAL) at CANDLE based on photocathode RF gun is under consideration. For several experimental setup purposes the linac will operate in single and multibunch modes with final beam energy 5-20 MeV and the bunch charge 10 –100 pC. The study of beam phase space evolution along the linac is performed to optimize the beam main characteristics: emittance, bunch length and energy spread. The dependence of longitudinal and transverse distribution of electrons in photocathode region on RF cavity performances is analyzed.  
 
TUPC034 Design Studies on 100 MeV/100 kW Electron Linac for NSC KIPT Neutron Source on the Base of Subcritical Assembly Driven by Linac linac, electron, gun, target 1075
 
  • Y.L. Chi, J. Cao, X.W. Dai, C.D. Deng, M. Hou, X.C. Kong, R.L. Liu, W.B. Liu, C. Ma, G. Pei, H. Song, S.H. Wang, G. Xu, J. Zhao, Z.S. Zhou
    IHEP Beijing, Beijing, People's Republic of China
  • M.I. Ayzatskiy, I.M. Karnaukhov, V.A. Kushnir, V.V. Mytrochenko, A.Y. Zelinsky
    NSC/KIPT, Kharkov, Ukraine
  • S. Pei
    IHEP Beijng, Beijing, People's Republic of China
 
  In NSC KIPT, Kharkov, Ukraine, a neutron source on the base of subcritical assembly driven by 100 MeV/100 kW electron linear accelerator is under design and development. To provide neutron flux value of about 1013 neutron/s the electron linear accelerator with 100 MeV beam and average beam power of 100 kW will be used. Construction and manufacture of the linear accelerator of such high beam intensity with low emittance and beam losses is a challenging task. In the report the project of the electron linear accelerator of the required beam energy and intensity is described. The accelerator structure and main technical solutions are presented. To overcome the BBU effect of this high average beam current, several effective measures are adopt, such as using constant gradient structure to spread the HOMs frequencies different cells, larger inner radius and shorter section length make the higher group velocity and optimize the structure geometry to keep the shunt impedance as good as possible. After the beam bunching system, a chicane is followed to chopper the beam to avoid the beam lost in the higher energy part.  
 
TUPC046 Alignment Tolerances for Vertical Emittance quadrupole, lattice, closed-orbit, dipole 1102
 
  • K.P. Wootton, R.P. Rassool, G. Taylor
    The University of Melbourne, Melbourne, Australia
  • M.J. Boland, R.T. Dowd, G. LeBlanc, Y.E. Tan
    ASCo, Clayton, Victoria, Australia
  • Y. Papaphilippou
    CERN, Geneva, Switzerland
 
  Alignment tolerances for the CLIC main damping ring magnetic lattice elements are presented. Tolerances are defined by the design equilibrium vertical emittance of 1 pm rad. The sensitivity of the uncorrected lattice to magnet misalignments is presented. Misalignments considered included quadrupole vertical offsets and rolls, sextupole vertical offsets, and main dipole rolls. Seeded simulations were conducted in MAD-X, and compared with expectation values calculated from theory. The lattice was found to be sensitive to betatron coupling as a result of sextupole vertical offsets in the arcs. Alignment tolerances, BPM and corrector requirements are presented also. For the same misalignment types, the equilibrium emittance of the corrected lattice is simulated. These are compared with expectation values calculated from theory. The vertical alignment tolerance of arc sextupoles is again demanding.  
 
TUPC049 Optics considerations for the Delay Loop in the CLIC Damping Rings Complex dipole, quadrupole, optics, damping 1108
 
  • P. Zisopoulos, F. Antoniou, H. Bartosik, Y. Papaphilippou
    CERN, Geneva, Switzerland
 
  For the recombination of the two trains coming from the CLIC damping rings, a delay loop will be used in order to obtain the nominal 0.5~ns bunch spacing. The optics design of the loop is based upon an isochronous ring, in order to preserve the longitudinal beam distribution. Analytical expressions for achieving isochronous conditions in high order for Theoretical Minimum Emittance cells are obtained. A parametrisation of the quadrupole settings for achieving these conditions is presented, along with general considerations regarding the choice of bending magnet characteristics.  
 
TUPC052 Normal Mode BPM Calibration for Ultralow-Emittance Tuning in Lepton Storage Rings quadrupole, coupling, alignment, simulation 1114
 
  • A. Wolski
    The University of Liverpool, Liverpool, United Kingdom
  • D. L. Rubin, D. Sagan, J.P. Shanks
    CLASSE, Ithaca, New York, USA
 
  BPMs capable of high-resolution turn-by-turn measurements offer the possibility of new techniques for tuning for ultra-low beam emittance. In this paper, we describe how signals collected from individual buttons during resonant beam excitation can be used to calibrate BPMs to read the beam position in a normal mode coordinate system. This allows for rapid minimization of the mode II emittance, simply by correcting the mode II dispersion. Simulations indicate that the technique is effective and robust, and has the benefit of being insensitive to BPM gain and alignment errors that can limit the effectiveness of other techniques.  
 
TUPC054 LHeC ERL Design and Beam-dynamics Issues linac, optics, HOM, cavity 1120
 
  • S.A. Bogacz, I. Shin
    JLAB, Newport News, Virginia, USA
  • D. Schulte, F. Zimmermann
    CERN, Geneva, Switzerland
 
  We discuss machine and beam parameter choices for a Linac-Ring option of the Large Hadron electron Collider (LHeC) based on the LHC. With the total wall-plug power limited to 100 MW and a target current of about 6 mA the desired luminosity of 1033 cm-2 s-1 can be reached, providing one exploits unique features of the Energy Recovery Linac (ERL). Here, we describe the overall layout of such ERL complex located on the LHC site. We present an optimized multi-pass linac optics enabling operation of the proposed 3-pass Recirculating Linear Accelerator (RLA) in the Energy Recovery mode. We also describe emittance preserving return arc optics architecture; including layout and optics of the arc switch-yard. Furthermore, we discuss importance of collective effects such as: beam breakup in the RLA, as well as ion accumulation, with design-integrated mitigation measures, and the electron-beam disruption in collision. Finally, a few open questions are highlighted.  
 
TUPC057 Femtosecond Photoinjector and Relativistic Electron Microscopy gun, electron, laser, cathode 1126
 
  • J. Yang, K. Kan, Y. Murooka, N. Naruse, K. Tanimura, Y. Yoshida
    ISIR, Osaka, Japan
  • J. Urakawa
    KEK, Ibaraki, Japan
 
  A new rf gun driven by a femtosecond laser has been developed successfully for the relativistic electron diffraction in Osaka University for the study of ultrafast dynamics of intricate molecular and atomic processes in materials. The beam dynamics of femtosecond electron bunch in the rf gun were investigated to achieve a low-emittance and low-energy-spread; i.e. 0.1 mm-mrad and 10-4. A time-resolved relativistic electron microscopy is being developed to reveal the hidden dynamics on the femtosecond and nanometer scales. The same demonstrations of the MeV electron diffraction/imaging measurements were reported.  
 
TUPC064 Transverse Phase Space Tomography in TRIUMF Injection Beamline space-charge, TRIUMF, quadrupole, injection 1144
 
  • Y.-N. Rao, R.A. Baartman
    TRIUMF, Canada's National Laboratory for Particle and Nuclear Physics, Vancouver, Canada
 
  Funding: TRIUMF receives funding via a contribution agreement through the National Research Council of Canada.
By tomography is meant the reconstruction of a 2-dimensional distribution from a number of 1-dimensional projections. In the case of transverse phase space, one records many profiles while varying a focusing device such as a quadrupole. Our aim was to investigate the two transverse phase space distributions in our 300keV H-minus beamline. We performed a series of measurements of beam profiles as a function of the voltage of an electrostatic quadrupole and used these along with the corresponding calculated transfer matrices in an iterative program based upon the Maximum Entropy algorithm, to find the phase space distributions. As well, we made measurements using an Allison-type emittance scanner to scan both planes. In this paper we present the details of these measurements, calculations, and we compare the two techniques.
 
 
TUPC073 Emittance Variation Dependence on Resonance Extraction Parameters at ELSA extraction, resonance, sextupole, septum 1168
 
  • S. Zander, O. Boldt, F. Frommberger, W. Hillert, O. Preisner
    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 stretcher ring providing a beam of polarized electrons with an energy of up to 3.5~GeV. In order to guarantee a high duty cycle, a slow extraction via a third integer resonance is applied to the stretcher ring. The emittance of the extracted beam as well as the efficiency of the extraction process depend on different parameters as the sextupole strength being necessary for the excitation of the third integer resonance or the adjusted tune. In order to optimize the quality of the extracted beam, an accurate comprehension of the influence of these parameters is indispensable. Beam profiles are detected using dedicated synchrotron light monitors optimized for low intensities. The emittance was investigated by the method of quadrupole scan. The experimental studies are accompanied by numerical simulation studies. The results of the change of the emittance depending on different resonance extraction setups obtained by the experimental as well as by the theoretical studies will be presented.
 
 
TUPC092 Transverse C-band Deflecting Structure for Longitudinal Phase Space Diagnostics in the XFEL/SPring-8 “SACLA” laser, vacuum, coupling, diagnostics 1221
 
  • H. Ego
    RIKEN/SPring-8, Hyogo, Japan
  • T. Hashirano, S. Miura
    MHI, Hiroshima, Japan
  • H. Maesaka, Y. Otake
    RIKEN Spring-8 Harima, Hyogo, Japan
  • T. Sakurai
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
 
  In SPring-8, the 8 GeV compact XFEL “SACLA” is under commissioning. A single bunch of electrons is compressed down to about 30 fs for brilliant SASE X-ray lasing. It is an important key of stable lasing to investigate the longitudinal phase space and the sliced emittance of a lasing part of the bunch by using a transverse RF deflector. We developed a high gradient C-band deflecting structure operated at 5712 MHz for the bunch diagnosis with a resolution of femtosecond regime at a limited space in the SACLA. The backward travelling-wave of the HEM11-5pi/6 mode is excited in the cylindrical structure periodically loaded with racetrack-shaped irises. The featuring irises suppress rotation of the deflection plane and generate strong cell-to-cell coupling for stable resonance. Two 1.8m-long structures were fabricated and installed in the SACLA. They successfully generated a deflection voltage over 40 MV and pitched the bunch at the zero-crossing RF phase. In this paper, we present the details of the fabrication and the deflecting performance of the structures applied to the diagnosis.  
 
TUPC095 Bucket-by-bucket On/Off-axis Injection with Variable Field Fast Kicker kicker, injection, dipole, quadrupole 1230
 
  • T. Nakamura
    JASRI/SPring-8, Hyogo-ken, Japan
 
  Dynamic aperture of ultra-low emittance storage rings is expected to be as small as a few mm; one order smaller than that of current rings, because of their high nonlinearity. The conventional injection scheme with bump formation may not be applied for such small aperture. On-axis injection with fast magnet is one of the solutions, however, it requires the injection beam of long trains of bunches, which impose serious limitation on the injector and the filling pattern. We propose a bucket-by-bucket on-axis/off-axis injection scheme, which manipulates the injection and stored beams bucket-by-bucket with a variable field fast kicker. For on-axis injection, this scheme eliminates the limitation on injectors and filling pattern, and also it can reject the contaminated electrons from the injector to keep the bunch purity. Those advantages allow the SPring-8 XFEL low emittance linac to be an injector matched with ultra-low emittance rings like the SPring-8 II: upgrade plan of SPring-8. By changing the drive power to the kicker, it can also produce position dependent kick required for the off-axis injection, with minimal perturbation on the stored beam achieved by bucket-by-bucket scheme.  
 
TUPC098 Beam Profile Measurement using Flying Wire Monitors at the J-PARC Main Ring* injection, simulation, space-charge, proton 1239
 
  • S. Igarashi, K. Ohmi, Y. Sato, M.J. Shirakata, M. Tejima, T. Toyama
    KEK, Ibaraki, Japan
  • Y. Hashimoto, K. Satou
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
 
  Transverse beam profiles have been measured using flying wire monitors at the main ring of the Japan Proton Accelerator Research Complex (J-PARC). The flying wire is a beam profile monitor using a thin carbon fiber as a target. The beam is scanned with the wire target at the maximum speed of 5 m/s. The secondary particles from the beam-wire scattering are detected using a scintillation counter as a function of the wire position. The measurement has revealed a characteristic temporal change of the beam profile during the injection period of 120 ms. A multiparticle tracking simulation program, SCTR, taking account of space charge effects has successfully reproduced the beam profiles.  
 
TUPC106 Courant-Snyder Invariant Density Screening Method for Emittance Analysis hadron, beam-transport, background, ion-source 1263
 
  • J.L. Sun, H.T. Jing, J. Tang
    IHEP Beijing, Beijing, People's Republic of China
 
  The emittance is an important characteristic of describing charged particle beams. In hadron accelerators, we often meet irregular beam distributions that are not appropriate to be described with a single rms or 95% or total emittance. In many cases beam halo should be described with very different Courant-Snyder parameters from the ones for beam core. A new method – Courant-Snyder invariant density screening method is developed for analyzing emittance data clearly and accurately. The method treats emittance data from both measurements and numerical simulations. The method uses the statistical distribution of the beam around each particle in phase space to mark its local density parameter, and then uses the density distribution to calculate the beam parameters such as Courant-Snyder parameters and emittance for different beam boundary definitions. The method has been used in the calculations for the beams from difference sources, and shows its advantages over other methods. An application code based on the method including the graphic interface has also been designed using the Matlab software.  
 
TUPC109 Electron Bunch Slice Emittance Measurement with the Space Charge Effects* solenoid, space-charge, electron, simulation 1272
 
  • C. Li, Y.-C. Du, W.-H. Huang, C.-X. Tang, L.X. Yan
    TUB, Beijing, People's Republic of China
 
  Funding: supported by the National Natural Science Foundation of China (Grant Nos. 10735050, 10805031, 10875070 and 10925523), and the National Basic Research Program of China (Grant No. 2007CB815102).
Since slice transverse emittance of the electron beam is critical to a high-gain short-wavelength FEL, its characterization is very important. For space charge dominated electron beam, conventional emittance measurement techniques, such as solenoid scanning and quadruple scanning, without considering space charge forces lead to large errors of emittance evaluations. This essay introduces a modified solenoid-scan method of slice emittance measurement for space charge dominated beam, and simulations show that the new method brings the emittance evaluations much closer to actual values.
 
 
TUPC110 Ultrashort Bunch Train Longitudinal Diagnostics using RF Deflecting Structure cavity, diagnostics, laser, betatron 1275
 
  • Y. Yang, H. Chen, Y.-C. Du, W.-H. Huang, C. Li, L.X. Yan
    TUB, Beijing, People's Republic of China
 
  Ultrashort electron bunch train has been produced using UV laser stacking in Tsinghua University. With an S-band deflecting cavity inserted into the Tsinghua Thomson Scattering beamline, it is possible to characterize the bunch train longitudinal property. This paper briefly introduced the measurement layout in our lab and reported the recent experiment results, including bunch train profile measurement and longitudinal phase space. The main sources of error are also discussed.  
 
TUPC111 Design of Cavity Beam Monitor at HLS cavity, quadrupole, gun, dipole 1278
 
  • 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”
X-FEL requires precious control of beam position and transverse emittance. Non-destructive on-line beam diagnostic methods are required. During the upgrading of HLS a high brightness injector based on photocathode RF electron gun, which can also be used to study FEL, is installed. The cavity beam monitor system designed for the HLS photocathode RF electron gun consists of a cavity beam position monitor and a beam quadrupole moment monitor system. The cavity beam position monitor uses a re-entrant position cavity tuned to TM110 mode as position cavity and cut-through waveguides to suppress the monopole signal. Cold test results showed that position resolution of prototype BPM is better than 3 μm. Beam quadrupole moment monitor system consists of a square pill-box quadrupole moment cavity, a cylindrical pill-box reference cavity, a waveguide coupling network and a superheterodyne receiver used as front-end signal processing system. The whole system works at 5.712 GHz. Strength of quadrupole magnets is adjust to construct a matrix which can be used to work out beam parameters.
 
 
TUPC124 Laser Wire Emittance Measurement Line at CLIC* laser, photon, collider, electron 1308
 
  • H. Garcia, Yu.A. Kubyshin
    UPC, Barcelona, Spain
  • T. Aumeyr, G.A. Blair
    JAI, Egham, Surrey, United Kingdom
  • D. Schulte, F. Stulle
    CERN, Geneva, Switzerland
 
  A precise measurement of the transverse beam size and beam emittances upstream of the final focus is essential for ensuring the full luminosity at future linear colliders. A scheme for the emittance measurements at the RTML line of the CLIC using laser-wire beam profile monitors is described. A lattice of the measurement line is discussed and results of simulations of statistical and machine-related errors and of their impact on the accuracy of the emittance reconstruction are given. Modes of operation of the laser wire system and its main characteristics are discussed.  
 
TUPC127 Optical Transition Radiation System for ATF2 target, coupling, simulation, radiation 1317
 
  • J. Alabau-Gonzalvo, C. Blanch Gutierrez, A. Faus-Golfe, J.J. García-Garrigós
    IFIC, Valencia, Spain
  • J. Cruz, D.J. McCormick, G.R. White, M. Woodley
    SLAC, Menlo Park, California, USA
 
  Funding: Funding Agency: FPA2010-21456-C02-01 Work supported in part by Department of Energy Contract DE-AC02-76SF00515
In this paper we present the first measurements performed during the fall 2010 and early 2011 runs. Software development, simulations and hardware improvements to the Multi-Optical Transition Radiation System installed in the beam diagnostic section of the Extraction (EXT) line of ATF2 are described. 2D emittance measurements have been performed and the system is being routinely used for coupling correction. Realistic beam simulations have been made and compared with the measurements. A 4D emittance procedure, yet to be implemented, is also discussed. A demagnifier lens system to improve the beam finding procedure has been designed and will be implemented in a future run. Finally, we discuss further verification work planned for the next run period of ATF.
 
 
TUPC132 Imaging of the MAX III Electron Beam Profile Using Visible Synchrotron Radiation electron, diagnostics, synchrotron, lattice 1332
 
  • A. Hansson, Å. Andersson, E.J. Wallén
    MAX-lab, Lund, Sweden
 
  The recently assembled MAX III diagnostic beam line utilizes the bending magnet synchrotron radiation (SR) in the visible to ultraviolet range to form images of the transverse electron beam profile. Computer simulations model the generation and propagation of the SR through the beam line, taking into account effects such as diffraction, the longitudinally distributed source point and the curvature of the electron orbit. Using the diagnostic beam line, the electron beam size and the emittance in the MAX III synchrotron light source has been determined.  
 
TUPC142 The Particle Identification System for the MICE Beamline Characterization beam-losses, electron, laser, solenoid 1356
 
  • M. Bonesini
    INFN MIB, MILANO, Italy
  • Y. Karadzhov
    DPNC, Genève, Switzerland
 
  The International Muon Ionization Cooling Experiment (MICE) will carry out a systematic investigation of a ionization cooling section of a muon beam, for the future Neutrino Factory and the future Muon Collider. As the emittance measurement will be done on a particle-by-particle basis, a sophisticated beam instrumentation is needed to measure both particle coordinates and timing vs RF in a harsh environment due to high particle rates, fringe magnetic fields and RF backgrounds. A PID system, based on three time-of-flight stations (with resolutions up to 50-60 ps), two Aerogel Cerenkov counters and a KLOE-like calorimeter (KL) has been constructed and has allowed the commissioning of the MICE muon beamline in 2010. It will be complemented in 2011 by an Electron Muon Ranger to determine the muon range at the downstream end of the cooling section. Detector performances, as obtained in the 2010 run, will be shown and the use of PD detectors for the beamline characterization, including a preliminary measure of emittance, fully illustrated.  
 
TUPC148 Measuring Emittance with the MICE Scintillating Fibre Trackers photon, simulation, alignment, factory 1374
 
  • D. Adey
    University of Warwick, Coventry, United Kingdom
 
  The Muon Ionization Cooling Experiment (MICE) aims to measure a 10% reduction in a muon beam emittance to within 0.1%. To achieve this two scintillating fibre trackers will be placed within a 4T solenoidal field. The trackers utilize fibres with a diameter of 350 microns to provide a position resolution of less than 0.5 mm. Details of the tracker hardware, electronics and its calibration and reconstruction methods will be presented, along with the measured performance under cosmic ray tests and the simulated performance in MICE.  
 
TUPC149 Measurements at the ALICE Tomography Section quadrupole, injection, simulation, background 1377
 
  • M.G. Ibison, K.M. Hock, D.J. Holder, B.D. Muratori, A. Wolski
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • M. Korostelev
    The University of Liverpool, Liverpool, United Kingdom
 
  Funding: STFC
This paper reports the results of tomography measurements of the electron beam transverse phase space distribution in the ALICE accelerator at Daresbury Laboratory. These measurements have two main aims. The first is to give a detailed picture of the phase space distribution of the electron beam injected from ALICE into the EMMA prototype non-scaling FFAG accelerator. The second is to provide data for the development and testing of a variety of techniques for tomographic reconstruction. We summarize the measurement results which we have obtained and discuss the advantages and disadvantages of some different tomography methods.
 
 
TUPC150 The Effect of Space-Charge on the Tomographic Measurement of Transverse Phase-Space in the EMMA Injection Line space-charge, quadrupole, injection, simulation 1380
 
  • M.G. Ibison, M. Korostelev
    The University of Liverpool, Liverpool, United Kingdom
  • K.M. Hock, D.J. Holder, B.D. Muratori, A. Wolski
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: STFC
Phase-space tomography for particle beams depends upon detailed knowledge of the particle transport through specified sections of a beam line. In the simplest case, only the effects of magnets (such as quadrupoles) and drift spaces need to be taken into account; however, in certain parameter regimes (high charge density and low energy) space charge forces may play a significant role. The ALICE accelerator is the electron source for EMMA, a prototype ns-FFAG machine. Results are presented of investigations into these effects on phase-space tomography in the injection line between ALICE and EMMA. The application of suitable correction techniques* to the EMMA injection line tomography measurements in the presence of space-charge is also discussed.
* D. Stratakis et al., Phys. Rev. ST Accel. Beams 9, 112801 (2006).
 
 
TUPC168 Results from the LHC BRAN Luminosity Monitor at Increased Luminosities luminosity, radiation, injection, simulation 1428
 
  • R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  • E. Bravin
    CERN, Geneva, Switzerland
  • H.S. Matis, A. Ratti, W.C. Turner, H. Yaver, T. stezelberger
    LBNL, Berkeley, California, USA
 
  Funding: This work supported by the US Department of Energy through the US LHC Accelerator Research Program (LARP).
The LHC BRAN luminosity monitors are used to monitor and optimize the luminosity at the LHC high luminosity interaction points IP1 and IP5. The Argon gas ionization chambers detect showers produced in the TAN absorbers by neutral particles emerging from pp collisions. The detectors have been operated during the 2010 run by counting the shower rate. As the current 2011 run has the multiplicity of proton-proton collisions per bunch crossing near ten, the detector sees more than one collision per bunch crossing. Therefore, the operation of the detector has been switched to pulse height mode to detect the average shower flux. This paper presents results from recent pulse height mode measurements, including the total and bunch-by-bunch luminosity as well as a determination of the crossing angle at these IPs. Comparisons with luminosity measurements from ATLAS and CMS are also presented.
 
 
TUPO008 Electron Linac Optimization for Driving Bright Gamma-ray Sources based on Compton Back-scattering electron, photon, linac, laser 1461
 
  • L. Serafini, F. Broggi, C. De Martinis, D. Giove
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • D. Alesini, P. Antici, A. Bacci, M. Bellaveglia, R. Boni, E. Chiadroni, G. Di Pirro, A. Esposito, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, E. Pace, A.R. Rossi, B. Spataro, P. Tomassini, C. Vaccarezza
    INFN/LNF, Frascati (Roma), Italy
  • A. Cianchi
    Università di Roma II Tor Vergata, Roma, Italy
  • C. Maroli, V. Petrillo
    Universita' degli Studi di Milano, Milano, Italy
  • M. Migliorati, A. Mostacci, L. Palumbo
    Rome University La Sapienza, Roma, Italy
 
  We study the optimal lay-out and RF frequency for a room temperature GeV-class Electron Linac aiming at producing electron beams that enhance gamma-ray sources based on Compton back-scattering. These emerging novel sources, generating tunable, mono-chromatic, bright photon beams in the range of 5-20 MeV for nuclear physics as well as nuclear engineering, rely on both, high quality electron beams and J-class high repetition-rate synchronized laser systems in order to achieve the maximum spectral density of the gamma-ray beam (# photons/sec/eV). The best option among the conventionally used RF linac-bands (S, C, X) and possible hybrid schemes will be analyzed and discussed, focusing the study in terms of best performances for the gamma-ray source, its reliability and compactness. We show that the best possible candidates for a Gamma-ray driver are quite similar to those of FEL Linacs.  
 
TUPO009 HiSOR-II, Compact Light Source with an Innovative Lattice Design lattice, focusing, synchrotron, radiation 1464
 
  • A. Miyamoto, S. Sasaki
    HSRC, Higashi-Hiroshima, Japan
 
  Funding: This work is partially supported by Cooperative and Supporting Program for Researches and Educations in University sponsored by KEK
We proposed a ring that a beam orbit is not closed with one turn and return to starting point after multiple turns around the ring. The idea of this new accumulation ring was inspired based on the torus knot theory. This ring has a long length of the total closed orbit in comparison with a conventional ring which has the orbit of one turn. Therefore this ring can have many straight sections and is advantageous to installation of insertion devices. We are designing a new ring based on the shape of a (3,11) torus knot for our future plan ‘HiSOR-II’. This ring has 11 long straight sections and can place undulators effectively by placing elements such as quadrupole magnets at the place near bending magnet, outside of the orbit crossing section. Furthermore, this ring has about 3 times longer circumference in comparison with the conventional ring, the diameter of the ring is as compact as 15 m, but its circumference is as long as 130 m. On the other hand, this ring must achieve low emittance to operate as the 3rd generation light source ring. Therefore we designed lattice of this ring in reference to MAX-III and achieved low emittance by using bending magnets with combined function.
 
 
TUPO023 Narrow Spectral Bandwidth Optimization of Compton Scattering Sources electron, laser, scattering, simulation 1488
 
  • F. Albert, S.G. Anderson, S.M. Betts, R.R. Cross, G.A. Deis, C.A. Ebbers, D.J. Gibson, F.V. Hartemann, T.L. Houck, R.A. Marsh, M. J. Messerly, C. Siders, S.S.Q. Wu
    LLNL, Livermore, California, USA
 
  We will be presenting the theoretical and numerical design and optimization of Mono-Energetic Gamma-Ray (MEGa-Ray) Compton scattering sources. A new precision source with up to 2.5 MeV photon energies, enabled by state of the art laser and x-band linac technologies, is currently being built at LLNL. Various aspects of the theoretical design, including dose and brightness optimization, will be presented. We will review the potential sources of spectral broadening, in particular due to the electron beam properties. While it is also known that nonlinear effects occur in such light sources when the laser normalized potential is close to unity, we show that these can appear at lower values of the potential. A three dimensional analytical model and numerical benchmarks have been developed to model the source characteristics based on given laser and electron beam distributions, including nonlinear spectra. Since MEGa-ray sources are being developed for precision applications such as nuclear resonance fluorescence, assessing spectral broadening mechanisms is essential.
This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
 
 
TUPO028 Emittance Compensation Scheme for the BERLinPro Injector space-charge, solenoid, linac, booster 1497
 
  • A.V. Bondarenko, A.N. Matveenko
    HZB, Berlin, Germany
 
  Following funding approval late 2010, Helmholtz-Zentrum Berlin officially started Jan. 2011 the design and construction of the Berlin Energy Recovery Linac Project BERLinPro. The initial goal of this compact ERL is to develop the ERL accelerator physics and technology required to accelerate a high-current (100 mA) low emittance beam (1 mm•mrad normalized), as required for future ERL-based synchrotron light sources. Given the flexibility ERLs provides, a short bunch operation mode will also be investigated. The space charge is the main reason of emittance degradation in injector due to rather low injection energy (7 MeV). The implementation of emittance compensation scheme in the injector is necessary to achieve such low emittance. Since injector’s optics is axially non-symmetric, the 2D- emittance compensation scheme* is proposed to be used. Other sources of emittance growth are also discussed.
* S.V. Miginsky, "Emittance compensation of elliptical beam", NIM A 603 (2009) 32.
 
 
TUPO029 Status of the BERLinPro Optics Design linac, vacuum, optics, electron 1500
 
  • A.N. Matveenko, M. Abo-Bakr, A.V. Bondarenko, A. Jankowiak, J. Knobloch, B.C. Kuske, Y. Petenev
    HZB, Berlin, Germany
 
  Following funding approval late 2010, Helmholtz-Zentrum Berlin officially started Jan. 2011 the design and construction of the Berlin Energy Recovery Linac Project BERLinPro. The initial goal of this compact ERL is to develop the ERL accelerator physics and technology required to accelerate a high-current (100 mA) low emittance beam (1 mm•mrad normalized), as required for future ERL-based synchrotron light sources. Given the flexibility ERLs provides, a short bunch operation mode will also be investigated. Current optics was designed to allow of low emittance and short bunch operation modes. Optics is flexible to suppress BBU and minimize CSR effects. Estimation of impact of ion accumulation, wake fields, halo and chromatic aberrations is given. Requirements for beam diagnostic system, alignment accuracy and power supply stability are investigated.  
 
TUPO033 Emittance Minimization by Courant-Snyder Parameter Scan in Merger Section at the Compact Energy Recovery Linear Accelerator. space-charge, betatron, SRF, dipole 1506
 
  • J.G. Hwang
    Kyungpook National University, Daegu, Republic of Korea
  • E.-S. Kim
    KNU, Deagu, Republic of Korea
  • T. Miyajima
    KEK, Tsukuba, Japan
 
  The project of compact-Energy Recovery Linac(c-ERL) at Photon Factory in KEK is a test facility for the 5 GeV ERL, which is one of the candidates of next generation light source. It consists of injector system, merger section, main SRF section, return arc, long straight section and beam dump. The injector system produces beams with a low-energy of 5 MeV and low-emittance less than 1 mm-mrad. It causes the large emittance growth by space charge force in merger section, which consists of two rectangular type dipole magnets and one sector type magnet. Dispersion also causes the displacement of bunch sllice on horizontal plane. The displacement of bunch slice is laid on the kick angle induced by space charge force. Also, each slice has the orientation of the phase ellipse on horizontal phase space. Therefore, the emittance growth due to the displacement of bunch sllice induced by space charge force in the horizontal phase space can be minimized by matching the displacement to the orientation of the phase ellipse at the exit of merger. We present the results of the emittance minimization performed by mathcing of the angle of the phase ellipse by scan of CS (Courant-Snyder) parameter.  
 
TUPS009 SEY of Al Samples from the Dipole Chamber of PETRA III at DESY electron, simulation, synchrotron, synchrotron-radiation 1533
 
  • D. R. Grosso, R. Cimino, M. Commisso
    INFN/LNF, Frascati (Roma), Italy
  • R. Flammini
    CNR-IMIP, Monterotondo Stazione RM, Italy
  • R. Larciprete
    ISM-CNR, Rome, Italy
  • R. Wanzenberg
    DESY, Hamburg, Germany
 
  At the synchrotron radiation facility PETRA III, tune spectra have been measured with some characteristics which are typically observed at other storage rings in connection with electron cloud effects. For some bunch filling patterns, an increase of the vertical emittance has been observed. To estimate such effects with the available e-cloud simulation codes, the detailed knowledge of the SEY (Secondary Electron Yield) of the Al chamber, is required. To the purpose, representative PETRA III Al samples, were studied in detail at the INFN-LNF Surface Science Laboratory. XPS (X-ray photoelectron spectroscopy) and SEY measurements were performed as a function of electron and argon ion conditioning. The SEY of the as received samples shows a maximum value of δmax ≅ 2.8. Electron conditioning at 500 eV kinetic energy, reduces the SEY to values between δmax ≅ 1.8 to 1.4 (depending on the actual sample analyzed). The XPS characterization of the sample surface, after several cycles of argon ion sputtering, shows clearly that the SEY variation is closely related to the oxidation state of the Al sample, reaching a δmax value as low as 1.3 for our cleanest surface.  
 
TUPS036 High Energy Beam Impacts on Beam Intercepting Devices: Advanced Numerical Methods and Experimental Set-up simulation, impedance 1614
 
  • A. Bertarelli, V. Boccone, F. Carra, F. Cerutti, A. Dallocchio, N. Mariani, M.A. Timmins
    CERN, Geneva, Switzerland
  • L. Peroni, M. Scapin
    Politecnico di Torino, Torino, Italy
 
  Funding: This work has been carried out through of the European Coordination for Accelerator Research and Development (EuCARD), co-sponsored by EU 7th Framework Program.
Beam Intercepting Devices are potentially exposed to severe accidental events triggered by direct impacts of energetic particle beams. State-of-the-art numerical methods are required to simulate the behavior of affected components. A review of the different dynamic response regimes is presented, along with an indication of the most suited tools to treat each of them. The consequences on LHC Tungsten Collimators of a number of beam abort scenarios were extensively studied, resorting to a novel category of numerical explicit methods, named Hydrocodes. Full shower simulations were performed providing the energy deposition distribution. Structural dynamics and shock wave propagation analyses were carried out with varying beam parameters, identifying important thresholds for collimator operation, ranging from onset of permanent damage up to catastrophic failure. Since the main limitation of these tools lies in the limited information available on constitutive material models under extreme conditions, a dedicated experimental program is proposed, relying on the HiRadMat test facility at CERN. Experimental aspects such as sample-holder design and test set-up are described.
 
 
TUPS078 Electron Beam Ion Sources – A New Access for Particle Acceleration ion, electron, ion-source, injection 1719
 
  • F. Ullmann, F. Grossmann, V.P. Ovsyannikov, A. Schwan
    DREEBIT GmbH, Dresden, Germany
  • G. Zschornack
    Technische Universität Dresden, Institut für Angewandte Physik, Dresden, Germany
 
  Electron Beam Ion Sources (EBISs) produce highly charged ions in a high density electron beam. Due to their operational principle EBISs have a lot of advantages although limited in ion output. Since the radial source region is given by a narrow electron beam the extracted ion beam features a very low transversal emittance. Moreover, the ions are ionized by a monoenergetic electron beam resulting in a small variation of the ion energy distribution, and thus in a very low longitudinal emittance. Together with a low basis pressure of less than 10-9 mbar this result in a high quality ion beam. The ions can be extracted as continuous beam as well as ion pulses with distinct pulse shapes. Providing almost any element with any charge state of up to completely ionized ions gives a large number of different projectiles and kinetic energies. The use of EBISs whether based on permanent magnets or on cryogen-free superconducting magnets has been proven in a variety of fields and applications. In addition, their compact design makes them transportable, low in operational costs, and guarantee easy handling.  
 
TUPZ002 90 m β* Optics for ATLAS/ALFA optics, luminosity, scattering, quadrupole 1798
 
  • S. Cavalier, P.M. Puzo
    LAL, Orsay, France
  • H. Burkhardt
    CERN, Geneva, Switzerland
  • A. Peskov
    NNGU, Nizhny Novgorod, Russia
 
  We describe a high β* optics developed for the ATLAS detector at the LHC interaction regions (IR1), Roman Pots have been installed 240 m left and right of IR1 to allow to measure the absolute luminosity and the total elastic cross section for ATLAS with ALFA (Absolute Luminosity for ATLAS). Ultimately, it is planned to preform these measurements at a very high β* of 2625 m. Here we describe a new, intermediate β* = 90 m optics, which has been optimized for compatibility with the present LHC running conditions. We described the main features and expected performance of this optics for ALFA.  
 
TUPZ006 Aperture Determination in the LHC Based on an Emittance Blowup Technique with Collimator Position Scan beam-losses, injection, optics, storage-ring 1810
 
  • R.W. Assmann, R. Bruce, M. Giovannozzi, G.J. Müller, S. Redaelli, F. Schmidt, R. Tomás, J. Wenninger, D. Wollmann
    CERN, Geneva, Switzerland
  • M. Alabau
    IFIC, Valencia, Spain
 
  A new method to determine the LHC aperture was proposed. The new component is a collimator scan technique that refers the globally measured aperture limit to the shadow of the primary collimator, expressed in σs of rms beam size. As a by-product the BLM response to beam loss is quantified. The method is described and LHC measurement results are presented.  
 
TUPZ009 LHC Machine Protection against Very Fast Crab Cavity Failures cavity, optics, luminosity, betatron 1816
 
  • T. Baer, R. Tomás, J. Tückmantel, J. Wenninger, F. Zimmermann
    CERN, Geneva, Switzerland
  • T. Baer
    Uni HH, Hamburg, Germany
  • R. Calaga
    BNL, Upton, Long Island, New York, USA
 
  For the high-luminosity LHC upgrade program (HL-LHC), the installation of crab cavities (CCs) is essential to compensate the geometric luminosity loss due to the crossing angle. The baseline is a local scheme with CCs around the ATLAS and CMS experiments. In a failure case (e.g. a CC quench), the voltage and/or phase of a CC can change significantly with a fast time constant of the order of a LHC turn. This can lead to large, global betatron oscillations of the beam. Against the background of machine protection, the influence of a CC failure on the beam dynamics is discussed. The results from dedicated tracking studies, including the LHC upgrade optics, are presented. Necessary countermeasures to limit the impact of CC failures to an acceptable level are proposed.  
 
TUPZ010 Longitudinal Emittance Blow-up in the LHC synchrotron, damping, feedback, acceleration 1819
 
  • P. Baudrenghien, A.C. Butterworth, M. Jaussi, T. Mastoridis, G. Papotti, E.N. Shaposhnikova, J. Tückmantel
    CERN, Geneva, Switzerland
 
  The LHC relies on Landau damping for longitudinal stability. To avoid decreasing the stability margin at high energy, the longitudinal emittance must be continuously increased during the acceleration ramp. Longitudinal blow-up provides the required emittance growth. The method was implemented through the summer of 2010. We inject band-limited RF phase-noise in the main accelerating cavities during the whole ramp of about 11 minutes. Synchrotron frequencies change along the energy ramp, but the digitally created noise tracks the frequency change. The position of the noise-band, relative to the nominal synchrotron frequency, and the bandwidth of the spectrum are set by pre-defined constants, making the diffusion stop at the edges of the demanded distribution. The noise amplitude is controlled by feedback using the measurement of the average bunch length. This algorithm reproducibly achieves the programmed bunch length of about 1.2 ns (4 σ) at flat top with low bunch-to-bunch scatter and provides a stable beam for physics coast.  
 
TUPZ013 Calculation Method for Safe Beta* in the LHC luminosity, optics, collimation, injection 1828
 
  • R. Bruce, R.W. Assmann, W. Herr, D. Wollmann
    CERN, Geneva, Switzerland
 
  One way of increasing the peak luminosity in the LHC is to decrease the beam size at the interaction points by squeezing to smaller values of beta*. The LHC is now in a regime where safety and stability determines the limit in beta*, as opposed to traditional optics limits. In this paper, we derive a calculation model to determine the safe beta*-values based on collimator settings and operational stability of the LHC. This model was used to calculate the settings for the LHC run in 2011. It was found that beta* could be decreased from 3.5 m to 1.5 m, which has now successfully been put into operation.  
 
TUPZ014 Luminosity Optimization for a Higher-Energy LHC luminosity, damping, radiation, proton 1831
 
  • C.O. Domínguez, F. Zimmermann
    CERN, Geneva, Switzerland
 
  A Higher-Energy Large Hadron Collider (HE-LHC) is an option to further push the energy frontier of particle physics beyond the present LHC. A beam energy of 16.5 TeV would require 20-T dipole magnets in the existing LHC tunnel, which should be compared with 7 TeV and 8.33 T for the nominal LHC. Since the synchrotron radiation power increases with the fourth power of the energy, radiation damping becomes significant for the HE-LHC. It calls for transverse and longitudinal emittance control vis-à-vis beam-beam interaction and Landau damping. The heat load from synchrotron radiation, gas scattering, and electron cloud also increases with respect to the LHC. In this paper we discuss the proposed HE-LHC beam parameters; the time evolution of luminosity, beam-beam tune shifts, and emittances during an HE-LHC store; the expected heat load; and luminosity optimization schemes for both round and flat beams.  
 
TUPZ015 Electron Cloud Parameterization Studies in the LHC electron, vacuum, simulation, beam-losses 1834
 
  • C.O. Domínguez, G. Arduini, V. Baglin, G. Bregliozzi, J.M. Jimenez, E. Métral, G. Rumolo, D. Schulte, F. Zimmermann
    CERN, Geneva, Switzerland
 
  During LHC beam commissioning with 150, 75 and 50-ns bunch spacing, important electron-cloud effects, like pressure rise, cryogenic heat load, beam instabilities or emittance growth, were observed. The main strategy to combat the LHC electron cloud relies on the surface conditioning arising from the chamber-surface bombardment with cloud electrons. In a standard model, the conditioning state of the beam-pipe surface is characterized by three parameters: 1. the secondary emission yield; 2. the incident electron energy at which the yield is maximum; and 3. the probability of elastic reflection of low-energy primary electrons hitting the chamber wall. Since at the LHC no in-situ secondary-yield measurements are available, we compare the relative local pressure-rise measurements taken for different beam configurations against simulations in which surface parameters are scanned. This benchmark of measurements and these simulations is used to infer the secondary-emission properties of the beam-pipe at different locations around the ring and at various stages of the surface conditioning. In this paper we present the methodology and first results from applying the technique to the LHC.  
 
TUPZ017 Luminosity and Beam Parameter Evolution for Lead Ion Beams in the LHC luminosity, simulation, ion, heavy-ion 1840
 
  • J.M. Jowett, R. Bruce, T. Mertens
    CERN, Geneva, Switzerland
 
  Heavy ion beams in the LHC are subject to strong blow-up and debunching effects from intra-beam scattering and luminosity-driven beam losses. The large nuclear charge is at the origin of these effects, both in the cross sections for simple Coulomb scattering and the ultraperipheral interactions occurring in the collisions. We compare predictions from our models with data on luminosity, beam size and intensity evolution from the first heavy ion run of the LHC. This analysis has to take account of the varying capabilities of the LHC beam instrumentation between injection and collision energies.  
 
TUPZ019 Transverse Emittance Preservation through the LHC Cycle injection, luminosity, extraction, controls 1843
 
  • V. Kain, B. Goddard, B.J. Holzer, J.M. Jowett, M. Meddahi, T. Mertens, F. Roncarolo
    CERN, Geneva, Switzerland
 
  The preservation of the transverse emittance is crucial for luminosity performance. At the LHC design stage the total allowed emittance increase was set to 7% throughout the LHC cycle. The proton run in 2010 showed that the injectors can provide beams with smaller emittances than nominal and higher bunch intensities. The LHC parameters are well under control and the emittances are kept below nominal until physics. The LHC luminosity goals for the first year of running could therefore be achieved with fewer bunches than initially foreseen. This paper will report on the measured emittance growth at injection from the SPS and the evolution of the emittance through the entire LHC cycle. Sources and possible cures for the observed emittance growth will be discussed.  
 
TUPZ022 Longitudinal Beam Measurements at the LHC: The LHC Beam Quality Monitor injection, pick-up, controls, damping 1852
 
  • G. Papotti, T. Bohl, F. Follin, U. Wehrle
    CERN, Geneva, Switzerland
 
  The LHC Beam Quality Monitor is a system that measures individual bunch lengths and positions, similarly to the twin system SPS Beam Quality Monitor, from which it was derived. The pattern verification that the system provides is vital during the injection process to verify the correctness of the injected pattern, while the bunch length measurement is fedback to control the longitudinal emittance blow up performed during the energy ramp. In 2010 the system could for example clearly detect instances of longitudinal instabilities and beam excitation due to excess RF noise. The algorithms used, the hardware implementation and the system integration in the LHC control infrastructure are presented in this paper, along with possible improvements.  
 
TUPZ023 Observation of Bunch to Bunch Differences due to Beam-beam Effects luminosity, injection, kicker, dynamic-aperture 1855
 
  • G. Papotti, R. Alemany-Fernandez, R. Giachino, W. Herr, T. Pieloni, M. Schaumann, G. Trad
    CERN, Geneva, Switzerland
 
  Due to the bunch filling schemes in the LHC the bunches experience a very different collision schedule and therefore different beam-beam effects. These differences and the effect on the performance have been observed and compared with the expectations. Possible limitations due to these effects are discussed.  
 
TUPZ025 Experience with Offset Collisions in the LHC luminosity, target, beam-losses, controls 1858
 
  • G. Papotti, R. Alemany-Fernandez, F. Follin, R. Giachino, W. Herr, T. Pieloni, M. Schaumann
    CERN, Geneva, Switzerland
  • R. Calaga, R. Miyamoto
    BNL, Upton, Long Island, New York, USA
 
  To keep the luminosity under control, some experiments require the adjustment of the luminosity during a fill, so-called luminosity leveling. One option is the separate the beams transversely and adjust the separation to the desired collision rate. The results from controlled experiments are reported and interpreted. The feasibility of this method for ultimate luminosities is discussed.  
 
TUPZ026 Alternative Working Point(s) at Injection for the LHC injection, coupling, optics, quadrupole 1861
 
  • R. Calaga, R. Miyamoto
    BNL, Upton, Long Island, New York, USA
  • R. Tomás
    CERN, Geneva, Switzerland
  • G. Vanbavinckhove
    NIKHEF, Amsterdam, The Netherlands
 
  Funding: This work partially supported by the US Department of Energy through the LHC Accelerator Research Program (LARP).
At present, the LHC operates with a different fractional tunes at injection and at collision energy due to improved dynamic aperture indicated by tracking studies. Therefore, a tune swing crossing the 10th order resonance is needed during the beta-squeeze. A new proposal to alter the working point to collision tunes already at injection and during an energy ramp is foreseen to avoid the tune jump. Simulations and measurements of the optics along with the beam emittances and lifetime are compared to the nominal injection tunes. Feasibility for a working point close to the 1/2 integer is also attempted.
 
 
TUPZ029 Observation of Coherent Beam-beam Effects in the LHC simulation, damping, beam-beam-effects, collider 1870
 
  • X. Buffat
    EPFL, Lausanne, Switzerland
  • R. Calaga, S.M. White
    BNL, Upton, Long Island, New York, USA
  • R. Giachino, W. Herr, G. Papotti, T. Pieloni
    CERN, Geneva, Switzerland
 
  Early collisions in the LHC with a very limited number of bunches with high intensities indicated the presence of coherent beam-beam driven oscillations. Here we discuss the experimental results and compare with the expectations.  
 
TUPZ032 LHC Luminosity Upgrade with Large Piwinski Angle Scheme: A Recent Look luminosity, collider, simulation, single-bunch 1879
 
  • C.M. Bhat
    Fermilab, Batavia, USA
  • F. Zimmermann
    CERN, Geneva, Switzerland
 
  Funding: Work is supported by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the U.S. Department of Energy and US LARP.
Luminosity upgrade at the LHC collider using bunches with constant line charge density (longitudinally flat bunches) but with same beam-beam tune shift at collision, the so called large Piwinski angle scheme* is being studied with renewed interest in recent years**. By design the total beam-beam tune shift at the LHC is less than 0.015. But the initial operational experience at the LHC indicates the possibility of operating with beam-beam tune shifts as high as 0.02. In view of this development we have revisited the requirements for the Large Piwinski Angle scheme at the LHC. In this paper we present a new parameter list supported by 1) calculations on the luminosity gain, 2) reduction of e-cloud issues on nearly flat bunches and 3) longitudinal beam dynamics simulations. We also make some remarks on the needed upgrades on the LHC injector accelerators.
* F. Ruggiero and F. Zimmermann, PRST-AB 5, 061001 (2002).
** C. M. Bhat, CERN-2009-004, pp. 106-114.
Thanks to O.Bruning, E.Shaposhnikova, H.Damerau, E.Mahner, F.Caspers & CERN BE/ABP & RF Depts.
 
 
TUPZ033 Measurements of Transverse Beam Diffusion Rates in the Fermilab Tevatron Collider antiproton, background, collider, electron 1882
 
  • G. Stancari, G. Annala, T.R. Johnson, D.A. Still, A. Valishev
    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).
The transverse beam diffusion rate vs. particle oscillation amplitude was measured in the Tevatron using collimator scans. All collimator jaws except one were retracted. As the jaw of interest was moved in small steps, the local shower rates were recorded as a function of time. By using a diffusion model, the time evolution of losses could be related to the diffusion rate at the collimator position. Preliminary results of these measurements are presented.
 
poster icon Poster TUPZ033 [1.036 MB]  
 
TUPZ035 RHIC Polarized Proton Status and Operation Highlights polarization, resonance, feedback, controls 1888
 
  • H. Huang, L. A. Ahrens, I.G. Alekseev, E.C. Aschenauer, G. Atoian, M. Bai, A. Bazilevsky, M. Blaskiewicz, J.M. Brennan, K.A. Brown, D. Bruno, A. Dion, K.A. Drees, W. Fischer, J.W. Glenn, X. Gu, L.T. Hoff, C. Liu, Y. Luo, W.W. MacKay, Y. Makdisi, G.J. Marr, A. Marusic, F. Méot, M.G. Minty, C. Montag, J. Morris, A. Poblaguev, V. Ptitsyn, G. Robert-Demolaize, T. Roser, W.B. Schmidke, V. Schoefer, D. Smirnov, S. Tepikian, J.E. Tuozzolo, G. Wang, K. Yip, A. Zaltsman, A. Zelenski, S.Y. Zhang
    BNL, Upton, Long Island, New York, USA
  • D. Svirida
    ITEP, Moscow, Russia
 
  RHIC op­er­a­tion as the po­lar­ized pro­ton col­lid­er pre­sents unique chal­lenges since both lu­mi­nos­i­ty and spin po­lar­iza­tion are im­por­tant. A lot of up­grades and mod­i­fi­ca­tions have been made since last po­lar­ized pro­ton op­er­a­tion. A 9 MHz rf sys­tem has been in­stalled to im­prove lon­gi­tu­di­nal match at in­jec­tion and to in­crease lu­mi­nos­i­ty. A ver­ti­cal sur­vey of RHIC was per­formed be­fore the run to get bet­ter mag­net align­ment. The orbit con­trol has also been im­proved this year. AGS po­lar­iza­tion trans­fer ef­fi­cien­cy is improved by a horizontal tune jump system. To pre­serve po­lar­iza­tion on the ramp, a new work­ing point was cho­sen with the ver­ti­cal tune near a third order res­o­nance. The orbit and tune control are essential for polarization preservation. To calibrate the polarization level at 250 GeV, polarized protons were accelerated up to 250GeV and decelerated back to 100GeV. The tune, orbit and chromaticity feedback is essential for this operation. The new record of luminosity was achieved with higher polarization at 250 GeV in this run. The overview of the changes and op­er­a­tion re­sults are pre­sent­ed in this paper.  
 
WEXA01 Challenges of 4th Generation Light Sources FEL, electron, undulator, photon 3798
 
  • C. Pellegrini
    SLAC, Menlo Park, California, USA
  • C. Pellegrini
    UCLA, Los Angeles, California, USA
 
  In the last few years Free Electron Lasers (FELs) have emerged as exceptionally exciting tools for new science. The results from FLASH (Hamburg) on biological imaging, LCLS (Stanford) which generated the first hard X-ray lasing and the projects proposed or in costruction around the world are rapidly moving the scientific community to the so called “fast science” which demands ultrashort pulses, fs synchronization, high brightness, high coherence X-rays. The basic SASE FEL process used so far converts energy jitter into jitter of the centralwavelength. Processes based on seeding and HGHG seem to offer a number of advantages in terms of bandwidth, coherence, stability and undulator length. This talk will present an overview of the 4th generation light sources, discussing the main challenges afforded in the construction of the operating facilities and considering the trends for the development of future facilities.  
slides icon Slides WEXA01 [10.640 MB]  
 
WEOAA03 Approach to a Start-to-end Simulation of 2-loop Compact Energy Recovery Linac electron, simulation, linac, optics 1909
 
  • M. Shimada, K. Harada, Y. Kobayashi, T. Miyajima, N. Nakamura, S. Sakanaka
    KEK, Ibaraki, Japan
  • R. Hajima
    JAEA, Ibaraki-ken, Japan
 
  Transport of an extreme low emittance electron beam is critical issue in an energy recovery linac. In particlar, the space charge effect on an electron bunch in the injector with lower than 5 - 10 MeV induces a large emittance growth. To suppress the emittance growth by such as an optimization of the solenoid magnets, a nonlinear effect should be clarified by a three dimensional tracking simulation. The cons is that it consumes a enormous simulation time. The approach is not suitable for a double loop circulation because the simulation time depends on the transport length. Therefore the beam dynamics and optics are calculated by a start-to-end (S2E) simulation, in which the simulation code is switched after the full acceleration. We used 'general particle tracking (GPT)' for injector electron beam and 'elegant' for a circulator electron beam.  
slides icon Slides WEOAA03 [3.951 MB]  
 
WEZA02 Colliders for B Factories quadrupole, luminosity, sextupole, factory 1931
 
  • H. Koiso
    KEK, Ibaraki, Japan
 
  Two new B factories, SuperB in Frascati and SuperKEKB in Tsukuba, aim at unprecedented luminosities close to 1036/cm2/s. The designs, status, challenges, and differences between the two machines are reported. Emphasis should be put on recent developments for the B factories. The presentation should include a realistic outlook.  
slides icon Slides WEZA02 [6.796 MB]  
 
WEODA01 Observations of Beam-beam Effects at High Intensities in the LHC luminosity, beam-beam-effects, dynamic-aperture, brightness 1936
 
  • W. Herr, R. Alemany-Fernandez, R. Giachino, G. Papotti, T. Pieloni
    CERN, Geneva, Switzerland
  • R. Calaga
    BNL, Upton, Long Island, New York, USA
  • E. Laface
    ESS, Lund, Sweden
  • M. Schaumann
    RWTH, Aachen, Germany
 
  First observations with colliding beams in the LHC with bunch intensities close to nominal and above are reported. In 2010 the LHC initially operated with few bunches spaced around the circumference. Beam-beam tune shifts exceeding significantly the design value have been observed. In a later stage crossing angles were introduced around the experiments to allow the collisions of bunch trains. We report the first experience with head-on as well as long range interactions of high intensity bunches and discuss the possible performance reach.  
slides icon Slides WEODA01 [0.409 MB]  
 
WEOAB03 The Production of High Quality Electron Beams in the ALPHA-X Laser Wakefield Accelerator electron, laser, plasma, radiation 1956
 
  • S.M. Wiggins, 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
    USTRAT/SUPA, Glasgow, United Kingdom
  • W.A. Gillespie
    University of Dundee, Nethergate, Dundee, Scotland, 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 high quality 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 characterized in terms of the charge, bunch length, energy spread and transverse emittance. The energy spectrum (with less than 1% measured energy spread) is obtained using a high resolution magnetic dipole imaging spectrometer while pepper-pot mask measurements show that the normalized transverse emittance is as low as 1.1 pi mm mrad (resolution limited). The conditions needed to obtain this high quality are discussed.
 
slides icon Slides WEOAB03 [2.904 MB]  
 
WEYB01 Diagnostics for Ultra-low Emittance Beams laser, polarization, radiation, optics 1959
 
  • J.W. Flanagan
    KEK, Ibaraki, Japan
 
  The achievement in recent years of beams with vertical emittance of a few pico-meters in a number of electron storage rings has presented challenges for diagnostics capable of beam size measurements in this regime. A number of different approaches have been developed for various machines (e.g. laser wire; interferometer; Shintake monitor; coded aperture; compound refractive lens). This presentation will review and compare the different methods, and discuss their strengths, weaknesses, ultimate limitations, and the situations where they might be appropriate; and consider possible future directions.  
slides icon Slides WEYB01 [2.553 MB]  
 
WEPC005 Concept for Controlled Transverse Emittance Transfer within a Linac Ion Beam ECR, solenoid, linac, quadrupole 2007
 
  • L. Groening
    GSI, Darmstadt, Germany
 
  Generally the two transverse emittances of a linac beam are quite similar in size (round beam). However, injection into subsequent rings often imposes stronger limits for the upper allowed value to one of these emittances. Provision of flat linac beams (different transverse emittances) thus can considerable increase the injection efficiency into rings. Round-to-flat transformation has been already demonstrated for electron beams. It was also proposed for angular momentum dominated beams from Electron-Cyclotron-Resonance sources. We introduce a concept to extend the transformation to ion beams that underwent charge state stripping without requiring their extraction from an ECR source. The concept is of special interest for beams from low-charge-state / high-particle-current sources. It can be also applied to stripping of H to proton beams.  
 
WEPC010 Investigations into Efficient Extraction and Acceleration of Beams from Ion Traps antiproton, extraction, ion, injection 2022
 
  • O. Karamyshev, G.A. Karamysheva
    MPI-K, Heidelberg, Germany
  • O. Karamyshev, A.I. Papash
    JINR, Dubna, Moscow Region, Russia
  • M.R.F. Siggel-King, C.P. Welsch
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
 
  Funding: Work supported by STFC, the Helmholtz Association and GSI under contract VH-NG.328
A number of exotic ion species, such as for example radioactive isotopes or antiprotons, are highly desirable at very low energies of some tens of keV for fundamental studies. In order to obtain cooled beams with low emittance and low momentum spread, these particles are often first captured in an ion trap, cooled and then extracted and accelerated before being used in experiments. The extraction mechanism and subsequent beam handling impacts critically on the final beam quality. In this contribnution, an optimized scheme for efficient beam extraction and acceleration from ion traps is presented. Field maps from different existing ion trap setups, such as for example the Musashi trap at CERN, are used as a basis for simulation studies into the beam dynamics. Input and final beam emittances are analyzed as a function of the extraction and acceleration field geometries and the performance of different possible scenarios is directly compared.
 
 
WEPC013 Tests for Low Vertical Emittance at Diamond using LET Algorithm coupling, quadrupole, simulation, lattice 2031
 
  • S.M. Liuzzo, M.E. Biagini, P. Raimondi
    INFN/LNF, Frascati (Roma), Italy
  • R. Bartolini
    JAI, Oxford, United Kingdom
 
  We present measurements recently performed at the Diamond Light Source, aimed at the achievement of low vertical emittance using the Low Emittance Tuning (LET) algorithm developed for a SuperB factory project presently in progress. The tests have been focused on the comparison between this method and the LOCO algorithm currently used at Diamond. Beam position monitor tilts estimate and multiple coupling response matrices have been introduced in the algorithm in order to optimize the procedure. After few iterations using vertical correctors and skew quadrupoles, very low vertical dispersion and emittance coupling, comparable to those obtained by LOCO, have been measured.  
 
WEPC017 Vertical Beam Size Correction at the SSRF Storage Ring coupling, quadrupole, betatron, simulation 2043
 
  • M.Z. Zhang, J. Hou, B.C. Jiang, H.H. Li, S.Q. Tian
    SINAP, Shanghai, People's Republic of China
 
  Vertical beam size is an important parameter for 3rd generation light source. Correcting the vertical beam size is a realistic way to increase brightness or beam lifetime without any additional equipments in a machine under operation. The main sources of vertical beam size are betatron coupling and vertical dispersion. At the SSRF storage ring, LOCO is used for vertical dispersion and coupling measurements and corrections. The betatron coupling and vertical dispersion is corrected by skew quadrupoles that calculated by LOCO. Vertical beam size can be changed from 10s um to several um for different purposes. Touschek lifetime is also measured to testify the vertical beam size. Simulations show that if smaller vertical beam size is required, more skew quadrupoles are needed.  
 
WEPC023 Beam Dynamics Simulations for the ESS-Bilbao H Ion Source extraction, ion, simulation, ion-source 2052
 
  • I. Bustinduy, F.J. Bermejo, D. Fernandez-Cañoto, J.L. Munoz, I. Rodríguez
    ESS Bilbao, Bilbao, Spain
  • M. Eguiraun, J. Feuchtwanger, Z. Izaola
    ESS-Bilbao, Zamudio, Spain
 
  Simulations are performed for the Ion Source Test Stand (ITUR) of the ESS-Bilbao research accelerator facility. The beam dynamics is investigated as a function of the extraction voltages, the ion current, and the inclination angle of the ion source. The ITUR Penning H− ion source has the plasma aperture plate and extraction electrode inclined a certain angle with respect to the vertical axis to compensate for the Penning magnets field. The negative charged particles are extracted through a rectangular slit of 10×6 mm2. The extraction system is mainly composed of two devices, a rectangular extraction electrode and a refrigerated trumpet shaped device acting as an Einzel lens to focus the beam, and also, as a trap for neutral cesium atoms exiting from the source. Results are calculated and analyzed at the DC Current Transformer and pepperpot positions located at 245 mm and 882 mm from the ion source.  
 
WEPC025 Modeling Results of the ALBA Booster booster, dipole, injection, quadrupole 2058
 
  • G. Benedetti, D. Einfeld, U. Iriso, J. Marcos, Z. Martí, M. Muñoz, M. Pont
    CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
 
  The 3rd generation light source ALBA is in the process of being commissioned. The full energy 3 GeV booster synchrotron was commissioned in the during 2010, ramping the beam from extracted from the LINAC from an energy of 110 MeV to the 3 GeV required for injection in the storage ring. The lattice is based in combined function bending magnets, providing a small emittance beam (< 12 nmrad) at extraction. This paper reviews the agreement between the optics modeling and the measures performed during the commissioning, with special regard to the optics measurement during the ramping process. The results from the magnetic measurement for the combined magnets while ramping are included in the model to explain the movement of the tunes during the ramp.  
 
WEPC035 Double Mini-Betay Lattice for TPS Storage Ring lattice, dynamic-aperture, multipole, quadrupole 2082
 
  • M.-S. Chiu, H.-P. Chang, C.-T. Chen, C.C. Chiang, C.-C. Kuo, Y.C. Lee, H.-J. Tsai, C.H. Yang
    NSRRC, Hsinchu, Taiwan
 
  Based on our previous design of double mini-betay optics in one 12-m straight section, NSRRC plan to implement the double mini-betay lattice in three 12-m straight sections in TPS storage ring. Those three locations chosen for double mini-betay lattice still retain the symmetry of accelerator lattice. The two symmetric minima of the vertical beta function will be created in the center of three 12-m straight sections, respectively. We strived to obtain a linear lattice such that there is no significant increase in the natural emittance. Efforts were devoted to optimize the nonlinear beam dynamics with various simulation tools. Preliminary results will be reported.  
 
WEPC039 Modelling of the FETS MEBT Line using GPT simulation, rfq, ion, linac 2094
 
  • D.C. Plostinar
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • R. Enparantza, M. Larrañaga
    Fundación TEKNIKER, Eibar (Gipuzkoa), Spain
 
  The Front End Test Stand project (FETS) currently under construction at Rutherford Appleton Laboratory (RAL) will accelerate a 60 mA, 2 ms, 50 pps H beam up to 3 MeV. It consists of an H ion source, a three-solenoid low energy beam transport line (LEBT), an RFQ and a medium energy beam transport line (MEBT) with a fast-slow beam chopping system. As part of the MEBT development, a GPT simulation model has been prepared. The aim is to analyse and understand the transport of intense beams and the beam behaviour in the space-charge dominated regime. The beam quality is then evaluated in terms of RMS emittance growth, beam loss, chopping efficiency and halo development. Results previously obtained with different simulation codes are discussed throughout the paper.  
 
WEPC043 Beam Transport in a Dielectric Wall Accelerator for Intensity Modulated Proton Therapy proton, focusing, beam-transport, accelerating-gradient 2106
 
  • Y.-J. Chen, D.T. Blackfield, 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.
We are developing a compact dielectric wall accelerator (DWA) for intensity modulated proton therapy (IMPT) with a goal of fitting the compact proton DWA in a single room*. To make the accelerator compact, the DWA needs to have a very high accelerating gradient. Also, beam transport in the DWA should be done with as few external lenses as possible. We have developed a transport scheme to transport the proton bunch in the DWA and to focus the charge bunch on the patient without using any external focusing lenses. The transport scheme would allow us change the proton beam spot size on the patient easily and rapidly. Results of simulations using 3-D, EM PIC code, LSP** will be presented.
* G. J. Caporaso, Y-J Chen and S. E. Sampayan, Rev. of Accelerator Science and Technology, vol. 2, p. 253 (2009).
** Alliant Techsystems Inc., http://www.lspsuite.com/.
 
 
WEPC045 Transverse Emittance Reduction with Tapered Foil scattering, electron, target, simulation 2112
 
  • Y. Jiao, Y. Cai, A. Chao
    SLAC, Menlo Park, California, USA
 
  Funding: The work is supported by the U.S. Department of Energy under contract No. DE-AC02-76SF00515.
The idea of reducing transverse emittance with tapered energy-loss foil is proposed by J.M. Peterson in 1980s and recently by B. Carlsten. In present paper, we present the physical model of tapered energy-loss foil and analyze the emittance reduction using the concept of eigen emittance. The study shows that, to reduce transverse emittance, one should collimate at least 4% of particles which has either much low energy or large transverse divergence. The multiple coulomb scattering is not trivial, leading to a limited emittance reduction ratio.
 
 
WEPC055 Beam Orbit and Power Converter Stability at the CR dipole, power-supply, antiproton, closed-orbit 2139
 
  • A. Dolinskii, C. Dimopoulou, O.E. Gorda, S.A. Litvinov, F. Nolden, M. Steck, H. Weick
    GSI, Darmstadt, Germany
 
  For the isochronous mode operation of the CR with reference to have good properties of the mass measurements we study the sources of the beam orbit fluctuation and as consequence power converter requirements for the CR operated at BR=13 Tm. This papaer presents a summary of the different factors causing beam orbit variation, which leads to reduction of the mass measurements precision. The requirements to the power converters have been addressed.  
 
WEPC067 The Spin Aberration of Polarized Beam in Electrostatic Rings cavity, simulation, lattice, dipole 2175
 
  • Y. Senichev, A. Lehrach, R. Maier, D. Zyuzin
    FZJ, Jülich, Germany
 
  For a beam with nonzero transverse emittance and momentum spread passing through an electric field, for example an electric focusing lens or deflector, the orientation of a spin vector becomes a function of 6D initial phase coordinates that leads to spin aberrations. We investigate this process analytically and numerically.  
 
WEPC078 Non-linear Chromaticity Studies of the LHC at Injection octupole, dipole, injection, optics 2199
 
  • E.H. Maclean, M. Giovannozzi, F. Schmidt, R.J. Steinhagen, E. Todesco, R. Tomás, G. Vanbavinckhove
    CERN, Geneva, Switzerland
  • R. Bartolini
    JAI, Oxford, United Kingdom
 
  The non-linear chromaticity of the LHC has been studied. Measurements of variation in tune with dp/p on both beams at injection optics are being compared with Q'' and Q''' as calculated with the LHC effective model. This model uses the best currently available measurements of magnetic field harmonics. An attempt is being made to optimize the b4 and b5 pool-pieces corrections in view of the corresponding chromaticity terms.  
 
WEPC080 Non-linear Dynamics Optimization of the CLIC Damping Rings resonance, dynamic-aperture, lattice, quadrupole 2205
 
  • Y. Renier, F. Antoniou, H. Bartosik, Y. Papaphilippou
    CERN, Geneva, Switzerland
  • K.P. Wootton
    The University of Melbourne, Melbourne, Australia
 
  Non-linear dynamics studies are undertaken in order to optimize the dynamic aperture of the CLIC damping rings. In this respect, advanced methods such as frequency map and resonance driving term analysis are used in order to explore the working point space with respect to single particle stability. The impact of magnet errors and misalignments, and in particular, the effect of the super-conducting damping wigglers is evaluated. Additional considerations for the working point choice are presented.  
 
WEPC101 Simulation of the Interaction of an Electron Beam with Ionized Residual Gas ion, simulation, electron, space-charge 2250
 
  • G. Pöplau, U. van Rienen
    Rostock University, Faculty of Computer Science and Electrical Engineering, Rostock, Germany
  • A. Meseck
    HZB, Berlin, Germany
 
  Funding: Supported by BMBF under contract number 05K10HRC
Light sources of the next generation such as ERLs require minimal beam losses as well as a stable beam position and emittance over the time. Instabilities caused by ion accumulation have to be avoided. In Rostock the tracking code MOEVE PIC Tracking has been developed for the simulation of space charge influenced beam dynamics, which is recently applied for simulations of the interaction beam - e-cloud. In this paper we apply MOEVE PIC Tracking for simulation of the interaction of the ionized residual gas with an electron bunch. We demonstrate numerical results with parameters planed for the ERL BERLinPro.
 
 
WEPC105 Multiparticle Simulation of Intrabeam Scattering for SuperB simulation, damping, scattering, lattice 2259
 
  • T. Demma, M.E. Biagini, M. Boscolo
    INFN/LNF, Frascati (Roma), Italy
  • K.L.F. Bane, A. Chao, M.T.F. Pivi
    SLAC, Menlo Park, California, USA
 
  Intrabeam scattering (IBS) is associated with multiple small angle scattering events leading to emittance growth. In most electron storage rings, the growth rates arising from IBS are much longer than damping times due to synchrotron radiation, and the effect on emittance growth is negligible. However, IBS growth rates increase with increasing bunch charge density, and for storage rings such as SuperB, that operate with high bunch charges and very low vertical emittance, the IBS growth rates can be large enough to produce significant emittance increase. Several formalisms have been developed for calculating IBS growth rates in storage rings*. However these models, based on Gaussian bunch distributions, cannot investigate some interesting aspects of IBS such as its evolution during the damping process and its effect on the beam distribution. We developed a multiparticle tracking code, based on the Binary Collision Model**, to investigate these effects. In this communication we present the structure of the code and simulation results obtained with particular reference to the SuperB parameters. Simulation results are compared with those of conventional IBS theories.
* A. Piwinski, Lect. Notes Phys. 296 (1988); J.D. Bjorken and S.K. Mtingwa, Part. Accel. 13 (1983); K. Kubo et al., Phys. Rev. ST-AB 8 (2005).
** Peicheng Yu et al., Phys. Rev. ST–AB 12 (2009).
 
 
WEPC109 Emittance Optimization Using Particle Swarm Algorithm* lattice, quadrupole, storage-ring, synchrotron 2271
 
  • Z. Bai, W. Li, L. Wang
    USTC/NSRL, Hefei, Anhui, People's Republic of China
 
  In this paper we use a swarm intelligence algorithm, particle swarm optimization (PSO), to optimize the emittance directly. Some constraint conditions such as beta functions, fractional tunes and dispersion function, are considered in the emittance optimization. We optimize the strengths and positions of quadrupoles to search low emittances. Here an FBA lattice studied in the design of the Hefei Advanced Light Source storage ring is used as the testing lattice. The PSO is shown to be beneficial in the optimization.  
 
WEPC168 Implementation of a Workflow Model to Store and Analyze Measured Data at the ESS-Bilbao Ion Source Test Stand ion, ion-source, diagnostics, controls 2376
 
  • Z. Izaola, M. Eguiraun, M. del Campo
    ESS-Bilbao, Zamudio, Spain
  • I. Bustinduy
    ESS Bilbao, Bilbao, Spain
 
  Funding: The present work is supported by the Basque Government and Spanish Ministry of Science and Innovation.
In order to fully characterize the experimentally measured beam in any accelerator facility, both diagnostics measurements and operating parameters need to be stored and correlated. Generating thus, a substantial amount of data. To address this problem in the ESS-Bilbao Ion Source Test Stand (ITUR), we have developed a software toolkit. This software stores Pepperpot, Faraday-Cup, Retarding Potential Analyzer, ACCT and DCCT measurements in a relational database associated with the operating parameter values at the time of measurement. Furthermore, the toolkit stores in the same database the beam transverse dynamics parameters processed from the pepperpot device. This allows to connect easily the beam physics with the accelerator running parameters. MySQL has been used as database backend and Matlab as programming language.
 
 
WEPO033 Update on the Modification and Testing of the MICE Superconducting Spectrometer Solenoids* solenoid, radiation, magnet-design, focusing 2469
 
  • S.P. Virostek, M.A. Green, N. Li, T.O. Niinikoski, H. Pan, S. Prestemon, M.S. Zisman
    LBNL, Berkeley, California, USA
  • A. Langner
    CERN, Geneva, Switzerland
 
  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, which will demonstrate ionization cooling in a segment of a realistic cooling channel using a muon beam. A pair of identical, 3-m long spectrometer solenoids will provide a 4-tesla uniform field region at each end of the cooling channel. The emittance of the beam as it enters and exits the cooling channel will be measured within the 400 mm diameter magnet bores. The magnets incorporate 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. Previous testing of the magnets had revealed several operational issues related to heat leak and quench protection. A quench analysis using Vector Fields software and detailed heat leak calculations have been carried out in order to assess and improve the magnet design. Details of the analyses and resulting magnet design modifications along with an update of the magnet assembly and testing progress will be presented here.
 
 
WEPS018 The Proposed CERN Proton-Synchrotron Upgrade Program injection, cavity, space-charge, electron 2520
 
  • S.S. Gilardoni, S. Bart Pedersen, W. Bartmann, S. Bartolome, O.E. Berrig, C. Bertone, A. Blas, D. Bodart, J. Borburgh, R.J. Brown, A.C. Butterworth, M.C.L. Buzio, C. Carli, P. Chiggiato, H. Damerau, T. Dobers, R. Folch, R. Garoby, B. Goddard, M. Gourber-Pace, S. Hancock, M. Hourican, P. Le Roux, L.A. Lopez Hernandez, A. Masi, G. Metral, Y. Muttoni, E. Métral, M. Nonis, J. Pierlot, S. Pittet, C. Rossi, I. Ruehl, G. Rumolo, L. Sermeus, R.R. Steerenberg, M. Widorski
    CERN, Geneva, Switzerland
 
  In the framework of the High-Luminosity LHC project, the CERN Proton Synchrotron would require a major upgrade to match the future beam parameters requested as pre-injector of the collider. The different beam dynamics issues, from space-charge limitations to longitudinal instabilities are discussed, as well as the proposed technical solutions to overcome them, covering the increase of the injection energy to RF related improvements.  
 
WEPS020 Study of an Energy Upgrade of the CERN PS Booster booster, injection, power-supply, extraction 2526
 
  • K. Hanke, O. Aberle, M. E. Angoletta, W. Bartmann, S. Bartolome, C. Bertone, A. Blas, J. Borburgh, D. Bozzini, A.C. Butterworth, C. Carli, P. Dahlen, T. Dobers, A. Findlay, R. Folch, N. Gilbert, J. Hansen, T. Hermanns, S. Jensen, P. Le Roux, L.A. Lopez Hernandez, E. Mahner, A. Masi, B. Mikulec, Y. Muttoni, A. Newborough, D. Nisbet, M. Nonis, S. Olek, M.M. Paoluzzi, S. Pittet, B. Puccio, V. Raginel, I. Ruehl, J. Tan, B. Todd, W.J.M. Weterings, M. Widorski
    CERN, Geneva, Switzerland
 
  CERN’s LHC injector chain will have to deliver beams with ultimate brilliance as the LHC is heading for increased luminosity in the coming years. In order to overcome bottlenecks in the injector chain, an increase of the beam transfer energy from the CERN Proton Synchrotron Booster (PSB) to the Proton Synchrotron (PS) has been investigated as a possible upgrade scenario. This paper gives an overview of the technical solutions and summarizes the conclusions of the feasibility study.  
 
WEPS035 Beam Measurements with the New RFQ Beam Matching Section at the Frankfurt Funneling Experiment rfq, ion, ion-source, diagnostics 2562
 
  • M. Baschke, A. Schempp, J.S. Schmidt
    IAP, Frankfurt am Main, Germany
  • H. Zimmermann
    Accelerator Services, Oberursel, 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. A new beam transport system between RFQ accelerator and deflector has been constructed and mounted. With these extended RFQ-electrodes the drift between the Two-Beam-RFQ and the rf-deflector will be minimized and therefore unwanted emittance growth reduced. After first rf measurements current work are beam tests with the improved Two-Beam-RFQ. First results will be presented.
 
 
WEPS043 From EUROTRANS to MAX: New Strategies and Approaches for the Injector Development rfq, DTL, cavity, linac 2583
 
  • C. Zhang, H. Klein, D. Mäder, H. Podlech, U. Ratzinger, A. Schempp, R. Tiede
    IAP, Frankfurt am Main, Germany
 
  Funding: The research leading to these results has received funding from the European Atomic Energy Community’s (Euratom) Seventh Framework Programme FP7/2007-2011 under grant agreement n° [269565].
As the successor of the EUROTRANS project, the MAX project is aiming to continue the R&D effects for a European Accelerator-Driven System and to bring the conceptual design to reality. The layout of the driver linac for MAX will follow the reference design made for the XT-ADS phase of the EUROTRANS project. For the injector part, new design strategies and approaches, e.g. half resonant frequency, half transition-energy between the RFQ and the CH-DTL, and using the 4-rod RFQ structure instead of the originally proposed 4-vane RFQ, have been conceived and studied to reach a more reliable CW operation at reduced costs. In this paper, the design and simulation results of the MAX injector are presented.
 
 
WEPS044 Status of the Ion Source and RFQ Test Bench at the Heidelberg Ion Beam Therapy Centre ion, rfq, ion-source, extraction 2586
 
  • R. Cee, E. Feldmeier, M. Galonska, Th. Haberer, J.M. Mosthaf, B. Naas, A. Peters, S. Scheloske, J. Schreiner, T. Winkelmann
    HIT, Heidelberg, Germany
 
  The possibility of cancer treatment with proton and carbon beams provides HIT (Heidelberg Ion Beam Therapy Centre) with an exceptional feature and gives it a unique position in Europe. In the future, the variety of available ions will be extended towards helium and oxygen. To allow fast switching between three of these ion species an additional ion-source / spectrometer combination will be installed in the LEBT. For comprehensive tests of the new components a dedicated test bench including a beam emittance analyzer has been set up at the HIT facility. It opens up the opportunity to perform detailed investigations of the improved ECR ion source with its enhanced extraction system and the redesigned RFQ of the HIT injector. Parallel to the measurements, the beam optical model of the assembly could be refined to better reproduce the beam diagnostic results. Since August 2010 the test bench has been in operation in different configurations. Behind the RFQ a beamline comprising a phase-probe-based time-of-flight system and beam current measurement devices is set up. The aim is to determine the RFQ working point and to validate the optimizations in terms of particle transmission.  
 
WEPS050 The MEBT Design for the China Accelerator Driven System rfq, cavity, diagnostics, quadrupole 2604
 
  • H. Geng, H.F. Ouyang, J. Tang
    IHEP Beijing, Beijing, People's Republic of China
  • Z. Li, S. Pei, F. Yan
    IHEP Beijng, Beijing, People's Republic of China
 
  The Medium Eneryg Beam Transport (MEBT) line plays an important role in transporting and matching the beam from the RFQ exit to the entrance to the next type of acceleration structures while provides enough beam diagnostics for beam commissing and tuning. The beam dynamics design for the 1GeV China Accelerator Driven System (CADS) is making great progress. In this paper, we will describe the design–both element choosing and beam dynamics study of the 3MeV MEBT for the CADS project.  
 
WEPS054 The Comparison of ADS Injector II with HWR Cavity and CH Cavity cavity, linac, proton, simulation 2616
 
  • Z.J. Wang, Y. He
    IMP, Lanzhou, People's Republic of China
 
  High current superconducting proton linac is being studied for Accelerator-driven System (ADS) Project hold by the Chinese Academic of Sciences (CAS). The injector II, which will accelerate proton beam from 2.1 MeV to 10 MeV, will be operated with superconducting cavity. At low energy part, there are two alternative choose, one is HWR cavity, the other is CH cavity. In this paper, the comparison of design with the two type cavities will be presented in view of beam dynamics.  
 
WEPS056 First Beam Test of 81.5 MHz RFQ for ITEP-TWAC rfq, simulation, ion, proton 2622
 
  • V. Andreev, N.N. Alexeev, A. Kolomiets, B. Kondratyev, V.A. Koshelev, A.M. Kozodaev, V.G. Kuzmichev, Y. Orlov, V. Stolbunov, T. Tretyakova
    ITEP, Moscow, Russia
 
  The 4 vane RFQ resonator with magnetic coupling windows as initial part of high-current Heavy Ion Linac for ITEP TWAC Facility is presently under commissioning at ITEP. It was constructed for acceleration of ions with 1/3 charge-to-mass ratio to the energy of 1.57 MeV/u with beam current up to 100 mA. Additional beam dynamics simulations have been carried out for actual fields of the RFQ in order to determine both extreme output beam properties for different ion species with charge-to-mass ratio in the range of 1-0.25 and limitations for high-brightness of the high-current injector. The beam test of RFQ has been started with protons at relatively low electrode voltage for experimental studying the RFQ beam dynamics. First results of the beam test in comparison with beam dynamics simulations are presented.  
 
WEPS061 ESS LINAC, Design and Beam Dynamics linac, cavity, quadrupole, proton 2637
 
  • M. Eshraqi, H. Danared
    ESS, Lund, Sweden
 
  The European Spallation Source, {\sc ESS}, will use a linear accelerator delivering a high intensity proton beam with an average beam power of 5~MW to the target station at 2.5~GeV in long pulses of 2~msec. The ESS {\sc Linac} will use two types of superconducting cavities, spoke resonators at low energy and elliptical cavities at high energies. The possibilities to upgrade to a higher power {\sc Linac} at fixed energy are considered. This paper will present a review of the superconducting {\sc Linac} design and the beam dynamics studies.  
 
WEPS076 Straight Scaling FFAG linac, vacuum, closed-orbit, instrumentation 2682
 
  • J.-B. Lagrange, Y. Ishi, Y. Kuriyama, Y. Mori, T. Planche, B. Qin, T. Uesugi, E. Yamakawa
    KURRI, Osaka, Japan
  • K. Okabe
    University of Fukui, Faculty of Engineering, Fukui, Japan
  • A. Sardet, R. Wasef
    LPSC, Grenoble Cedex, France
 
  Recent developments in scaling fixed field alternating gradient (FFAG) accelerators have opened new ways for lattice design, with straight sections, and insertions like dispersion suppressors. An experiment to study straight sections and dispersion suppressors is under progress at KURRI.  
 
WEPS080 Development of High-quality Intense Proton Beam at the RCNP Cyclotron Facility proton, cyclotron, extraction, cavity 2694
 
  • M. Fukuda, K. Hatanaka, M. Kibayashi, S. Morinobu, K. Nagayama, T. Saito, H. Tamura, H. Ueda, H. Yamamoto, T. Yorita
    RCNP, Osaka, Japan
 
  A 2.45 GHz ECR proton source, equipped with a set of three permanent magnets, was developed to increase the intensity of a high-quality proton beam. A 15 keV proton beam with intensity of 0.6 mA was produced with a proton ratio of more than 80 %. Emittance of the proton beam with intensity of 50 to 100 micro-A in the LEBT system was around 50 pi-mm-mrad. Beam transmission, defined by the ratio of the beam intensity between a Faraday cup placed in the axial injection beam line and an inflector electrode of the AVF cyclotron, was improved from 25 % for a 70 micro-A proton beam to more than 90 % for 30 micro-A obtained by defining the injection beam with a beam slit of iris type. The result indicated that the beam transmission was limited by the acceptance of the axial injection beam line. Emittance of the 65 MeV proton beam accelerated by the K140 AVF cyclotron was a few pi-mm-mrad for beam intensity of several-micro-A. In this paper, development of the intense proton beam and evaluation of the proton beam quality will be mainly reported.  
 
WEPS088 Space Charge Studies of a 1 GeV Isochronous Non-scaling FFAG Proton Driver space-charge, acceleration, lattice, simulation 2715
 
  • S.L. Sheehy
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
 
  The production of very high power proton drivers in the 10 MW range is a considerable challenge to the accelerator community. Non-scaling FFAGs have gained interest in this field, as they may be able to provide smaller, cheaper accelerators than existing options. The recent development of an isochronous non-scaling FFAG is a promising advance, but must be shown to have stable beam dynamics in the presence of space charge. Simulations of this design including space charge are presented and the implications discussed.  
 
WEPS099 Physics Design of CSNS RCS Injection and Extraction System extraction, injection, kicker, septum 2739
 
  • J. Qiu, N. Huang, J. Tang, S. Wang
    IHEP Beijing, Beijing, People's Republic of China
 
  In this paper, the injection and extraction system design for CSNS RCS are discussed. The injection system is designed to place all the injection devices in one uninterrupted long drift in one of the four dispersion free straight sections. Painting bumper magnets are used for both horizontal and vertical phase space painting. The beam extraction process from the CSNS RCS is a single turn two step process, requiring a group of kickers and a Lambertson septum magnet.  
 
WEPS102 Latest News on the Beam Dynamics Design of SPL cavity, linac, quadrupole, lattice 2748
 
  • P.A. Posocco, M. Eshraqi, A.M. Lombardi
    CERN, Geneva, Switzerland
 
  SPL is a superconducting H− LINAC under study at CERN. The SPL is designed to accelerate the 160 MeV beam of LINAC4 to 5 GeV, and is composed of two fami¬lies of 704.4 MHz elliptical cavities with geometrical betas of 0.65 and 1.0. Two families of cryo-modules are considered: the low-beta cryo-module houses 3 low-beta cavities, whereas the high-beta one houses 8 cavities. The transverse focusing is performed with normal-conducting quadrupoles arranged in 2 different lattices: FD0 at lower and F0D0 at higher energies. The regular lattices are in-terrupted at the transition between low beta and high beta cryo-modules and for extracting medium energy beams at 1.4 and 2.5 GeV, where the change of the transverse lattice is performed. In this paper the latest beam dynamics studies will be presented together with the sensitivity of the SPL performance to RF errors, alignment tolerances and quadrupole high order components.  
 
WEPS107 Phase Space Coating in Synchrotrons: Some Applications* synchrotron, antiproton, brightness, simulation 2763
 
  • C.M. Bhat
    Fermilab, Batavia, USA
 
  Funding: Operated by Fermi Research Alliance, LLC under Contract No. DE-AC02-07CH11359 with the United States Department of Energy
Phase-space painting to produce very high intensity beam in synchrotrons is one of the widely studied topics in accelerator physics. A remarkable example of this is multi-turn beam injection by transverse phase-space painting in spallation sources. Use of barrier buckets at synchrotron storage rings has paved way for further advancements in this field. The Fermilab Recycler, antiproton storage ring, has been augmented with multipurpose broad-band barrier rf systems. Recently we have developed a longitudinal phase-space coating technique over already e-cooled high intensity low longitudinal antiproton beam and demonstrated with beam experiments. This method is extended to map the incoherent synchrotron tune of beam particles in a barrier bucket. Here I review various phase-space painting techniques being used in particle accelerators including some new schemes developed using barrier rf systems and possible new applications.
 
 
WEPZ002 Chromatic, Geometric and Space Charge Effects on Laser Accelerated Protons Focused by a Solenoid solenoid, proton, laser, ion 2766
 
  • H.Y. Al-Omari, U. Ratzinger
    IAP, Frankfurt am Main, Germany
  • I. Hofmann
    GSI, Darmstadt, Germany
 
  We studied numerically emittance and transmission effects by chromatic and geometric aberrations, with and without space charge, for a proton beam behind a solenoid in the laser proton experiment LIGHT at GSI. The TraceWin code was employed using a field map for the solenoid and an initial distribution with exponential energy dependence close to the experiment. The results show a strong effect of chromatic, and a relatively weak one of geometric aberrations as well as dependence of proton transmission on distance from the solenoid. The chromatic effect has an energy filtering property due to the finite radius beam pipe. Furthermore, a relatively modest dependence of transmission on space charge is found for p production intensity below 1011.  
 
WEPZ011 Fast Cooling of Bunches in Compton Storage Rings laser, electron, scattering, photon 2790
 
  • E.V. Bulyak
    NSC/KIPT, Kharkov, Ukraine
  • J. Urakawa
    KEK, Ibaraki, Japan
  • F. Zimmermann
    CERN, Geneva, Switzerland
 
  We propose an enhancement of laser radiative cooling by utilizing laser pulses of small spatial and temporal dimensions, which interact only with a fraction of an electron bunch circulating in a storage ring. We studied the dynamics of such electron bunch when laser photons scatter off the electrons at a collision point placed in a section with nonzero dispersion. In this case of ‘asymmetric cooling', the stationary energy spread is much smaller than under conditions of regular scattering where the laser spot size is larger than the electron beam; and the synchrotron oscillations are damped faster. Coherent oscillations of large amplitude may be damped within one synchrotron period, so that this method can support the rapid successive injection of many bunches in longitudinal phase space for stacking purposes. Results of extensive simulations are presented for the performance optimization of Compton gamma-ray sources and damping rings.  
 
WEPZ017 ESTB: A New Beam Test Facility at SLAC electron, kicker, hadron, linac 2808
 
  • M.T.F. Pivi, H. Fieguth, C. Hast, R.H. Iverson, J. Jaros, R.K. Jobe, L. Keller, T.V.M. Maruyama, D.R. Walz, M. Woods
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by the Director, Office of Science, High Energy Physics, U.S. DOE under Contract No. DE-AC02-76SF00515.
End Station A Test Beam (ESTB) is a beam line at SLAC using a small fraction of the bunches 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. ESTB will provide one of a kind test beam essential for developing accelerator instrumentation and accelerator R&D, performing particle and particle astrophysics detector research, linear collider machine and detector interface (MDI) R&D studies, development of radiation-hard detectors, and material damage studies with several distinctive features. In the past, 18 institutions participated in the ESA program at SLAC. In stage I, 4 new kicker magnets will be added to divert 5 Hz of the LCLS beam to ESA. A new beam dump is installed and a new Personnel Protection System (PPS) is built in ESA. In stage II, we plan to install a secondary hadron target, able to produce pions up to about 12 GeV/c at 1 particle/pulse. We report about the ESTB commissioning, status and plan for tests.
 
 
WEPZ027 Stabilization of the LWFA and its Application to the Single-shot K-edge Densitometry electron, scattering, laser, wakefield 2823
 
  • K. Koyama, H. Madokoro, Y. Matsumura
    University of Tokyo, Tokyo, Japan
  • R. Kuroda, K. Yamada
    AIST, Tsukuba, Ibaraki, Japan
  • H. Masuda, M. Uesaka
    The University of Tokyo, Nuclear Professional School, Ibaraki-ken, Japan
  • S. Masuda
    Osaka University, Suita, Osaka, Japan
 
  Funding: This work was supported in part by Global COE Program “Nuclear Education and Research Initiative,” MEXT, Japan
Injection of electrons into a laser wakefield accelerator (LWFA) via a wavebreaking process was investigated in order to obtain stable output of electron bunches. A density down ramp for occurring the wavebreaking was formed by an oblique shockwave, which was excited by setting a little flow-deflector on an edge of the supersonic nozzle of high-Mach number (M=5). Parameters of the jet were examined by using PIC code and evaluated by using an interferometer, the density was 1019cm-3, density ratio was 2, and the characteristic length was 70 microns. Injection experiments using 7-TW laser pulses suggested that electrons were injected in the density ramp. Since the all-optical Compton X-ray is attractive source for an accurate densitometry, a preliminary experiment of a single-shot K-edge densitometry was performed by using X-ray pulses generated by the laser-Compton scattering (LCS) device based on a compact S-band 40 MeV linac at AIST. The single-shot K-edge densitometry was also applicable to evaluate the transverse emittance of electron bunches.
 
 
WEPZ028 Status of Plasma Electron Hose Instability Studies in FACET plasma, electron, simulation, ion 2826
 
  • E. Adli
    University of Oslo, Oslo, Norway
  • W. An, W.B. Mori
    UCLA, Los Angeles, California, USA
  • R.J. England, J.T. Frederico, M.J. Hogan, S.Z. Li, M.D. Litos, Y. Nosochkov
    SLAC, Menlo Park, California, USA
 
  Funding: This work is supported by the Research Council of Norway, the Fulbright Visiting Scholar Program and US DOE contract DE-AC02-76SF00515.
In the FACET plasma-wakefield acceleration experiments a dense 23 GeV electron beam will interact with lithium and cesium plasmas, leading to plasma ion-channel formation. The interaction between the electron beam and the plasma sheath-electrons may lead to a fast growing electron hose instability. By using optics dispersion knobs to induce a controlled z-x tilt along the beam entering the plasma, we investigate the transverse behavior of the beam in the plasma as function of the tilt. We seek to quantify limits on the instability in order to further explore potential limitations on future plasma wakefield accelerators due to the electron hose instability.
 
 
WEPZ036 A Multi-Parameter Optimization of Plasma Density for an Advanced Linear Collider plasma, ion, focusing, electron 2841
 
  • P. Muggli
    USC, Los Angeles, California, USA
  • R.W. Assmann
    CERN, Geneva, Switzerland
  • S. Hillenbrand
    KIT, Karlsruhe, Germany
  • P. Muggli
    MPI, Muenchen, Germany
 
  Funding: Work supported by US DoE
Recent plasma wakefield accelerator (PWFA) experiments showed that an accelerating gradient as high as 50GV/m can be driven and sustained over a meter-long plasma*. Based on this result, a strawman design for a future, multi-stage, PWFA-based electron/positron collider with an energy gain of ~25GeV/stage has been generated**. However, the choice of plasma density remains open. On one hand, high density means large accelerating gradients and possibly a shorter collider. On the other it means that the accelerating structure dimensions become very small, on the order of the plasma wavelength (<100 microns in each dimension?). Operating at high gradient and with such small structure imposes very strong constraints on the particle bunches: small dimensions and spacing, large current or limited charge, etc. These constraints result in challenges in producing bunches (compression, shaping for optimum loading, etc.) and could limit the achievable collider luminosity (beam-beam effects, etc.). We explore the global implications of operating at a lower accelerating gradient with the goal of relaxing the beam and plasma parameters while meeting the requirements of the collider.
* P. Muggli and M.J. Hogan, Comptes Rendus Physique, 10(2-3), 116 (2009).
** A. Seryi, M.J. Hogan, T. Raubenheimer, private communication.
 
 
THYA01 Beam Dynamics in Positron Injector Systems for Next Generation B Factories positron, linac, injection, target 2857
 
  • N. Iida, H. Ikeda, T. Kamitani, M. Kikuchi, K. Oide, D.M. Zhou
    KEK, Ibaraki, Japan
 
  SuperKEKB, the upgrade plan of KEKB, aims to boost the luminosity up to 8x1035 /cm2/s. The beam energy of the Low Energy Ring (LER) is 4 GeV for positrons, and that of the High Energy Ring is 7 GeV for electrons. SuperKEKB is designed to produce low emittance beams. The horizontal and vertical emittances of the injection beams are 12.5 nm and 0.9 nm, respectively, which are one or two orders smaller than those of KEKB. The normal and maximum required charges are 4 nC and 8nC, respectively. The positron injector system consists of the source, capture systems, L-band and S-band linacs, collimators, an energy compression system (ECS), a 1.1-GeV damping ring, a bunch compression system (BCS), S-band and C-band linacs, another ECS and a beam transport line into the LER. For the low emittance beam with a huge amount of the positron charge like 8nC, some kinds of issues by the instabilities will be predicted due to such as Coherent Synchrotron Radiation (CSR), beam loading, beam-beam effects, and so on. This paper reports a design of the positron beam injection system for SuperKEKB. In addition, comparisons with SuperB are described.  
slides icon Slides THYA01 [7.572 MB]  
 
THOBA01 Electron Cloud Observations in LHC electron, vacuum, injection, simulation 2862
 
  • G. Rumolo, G. Arduini, V. Baglin, H. Bartosik, P. Baudrenghien, N. Biancacci, G. Bregliozzi, S.D. Claudet, R. De Maria, J. Esteban Muller, M. Favier, C. Hansen, W. Höfle, J.M. Jimenez, V. Kain, E. Koukovini, G. Lanza, K.S.B. Li, G.H.I. Maury Cuna, E. Métral, G. Papotti, T. Pieloni, F. Roncarolo, B. Salvant, E.N. Shaposhnikova, R.J. Steinhagen, L.J. Tavian, D. Valuch, W. Venturini Delsolaro, F. Zimmermann
    CERN, Geneva, Switzerland
  • C.M. Bhat
    Fermilab, Batavia, USA
  • U. Iriso
    CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
  • N. Mounet, C. Zannini
    EPFL, Lausanne, Switzerland
 
  Operation of LHC with bunch trains different spacings has revealed the formation of an electron cloud inside the machine. The main observations of electron cloud build-up are the pressure rise measured at the vacuum gauges in the warm regions, as well as the increase of the beam screen temperature in the cold regions due to an additional heat load. The effects of the electron cloud were also visible as a strong instability and emittance growth affecting the last bunches of longer trains, which could be improved running with higher chromaticity and/or larger transverse emittances. A summary of the 2010 and 2011 observations and measurements and a comparison with existing models will be presented. The efficiency of scrubbing and scrubbing strategies to improve the machine running performance will be also briefly discussed.  
slides icon Slides THOBA01 [2.911 MB]  
 
THYB01 Advanced Beam Manipulation Techniques at SPARC gun, linac, simulation, laser 2877
 
  • A. Mostacci, D. Alesini, P. Antici, A. Bacci, M. Bellaveglia, R. Boni, M. Castellano, E. Chiadroni, G. Di Pirro, A. Drago, M. Ferrario, A. Gallo, G. Gatti, A. Ghigo, E. Pace, A.R. Rossi, B. Spataro, C. Vaccarezza
    INFN/LNF, Frascati (Roma), Italy
  • A. Cianchi
    Università di Roma II Tor Vergata, Roma, Italy
  • B. Marchetti
    INFN-Roma II, Roma, Italy
  • M. Migliorati
    University of Rome "La Sapienza", Rome, Italy
  • L. Palumbo
    Rome University La Sapienza, Roma, Italy
  • V. Petrillo, L. Serafini
    Istituto Nazionale di Fisica Nucleare, Milano, Italy
  • C. Ronsivalle
    ENEA C.R. Frascati, Frascati (Roma), Italy
 
  SPARC in Frascati is a high brightness photo-injector used to drive Free Electron Laser experiments and explore advanced beam manipulation techniques. The R&D effort made for the optimization of the beam parameters will be presented here, together with the major experimental results achieved. In particular, we will focus on the generation of sub-picosecond, high brightness electron bunch trains via velocity bunching technique (the so called comb beam). Such bunch trains can be used to drive tunable and narrow band THz sources, FELs and plasma wake field accelerators.  
slides icon Slides THYB01 [20.772 MB]  
 
THPC002 Implementation of a Low-Emittance Optics for the LNLS UVX Storage Ring optics, quadrupole, lattice, storage-ring 2907
 
  • F. H. de Sá, L. Liu, X.R. Resende
    LNLS, Campinas, Brazil
 
  In this report we describe the theoretical optimization and implementation of a low-emittance optics for the LNLS UVX storage ring. The emittance is reduced by letting the dispersion be distributed everywhere while keeping the low vertical beta feature. The optimization strategy is based on a series of quadrupole strength scans and selection of points satisfying a number of criteria. The new mode reduces the emittance from 100 nm.rad to 40 nm.rad, including the effects of the already installed insertion devices, and keeps the working point in the same quadrant as the present operation BBY6T mode. Tests have shown a reduction of approximately 20% in the horizontal and vertical beam sizes in the middle of the dipoles, in agreement with the theoretical emittance reduction.  
 
THPC008 Touschek Lifetime and Momentum Acceptance Measurements for ESRF vacuum, scattering, synchrotron, electron 2921
 
  • B. Nash, F. Ewald, L. Farvacque, J. Jacob, E. Plouviez, J.-L. Revol, K.B. Scheidt
    ESRF, Grenoble, France
 
  The Touschek lifetime of a synchrotron results from electrons scattering off one another within the bunch and subsequently being lost. We have measured the Touschek lifetime for the major operating modes of the ESRF as a function of RF voltages. This includes multibunch and few bunch filling patterns with correspondingly different chromaticity values. Through calibration of the RF voltage and measurement of the other beam parameters such as bunch length and vertical emittance, we may understand the momentum acceptance in the regime where this is determined by non-linear dynamics effects.  
 
THPC009 Performance and Upgrade of the ESRF Light Source undulator, cavity, storage-ring, vacuum 2924
 
  • J.-L. Revol, J.C. Biasci, J-F. B. Bouteille, J. Chavanne, F. Ewald, L. Farvacque, A. Franchi, G. Gautier, L. Goirand, M. Hahn, L. Hardy, J. Jacob, J.M. Koch, M.L. Langlois, G. Lebec, J.M. Mercier, T.P. Perron, E. Plouviez, K.B. Scheidt, V. Serrière
    ESRF, Grenoble, France
 
  The European Synchrotron Radiation Facility (ESRF) is now fully engaged in a large Upgrade Programme of its infrastructure, beamlines and X ray source. In this context, a first set of 10 insertion device straight sections are being lengthened from five to six metres; a number of them will be operated with canted undulators. The insertion devices are themselves subject to an ambitious development programme to fulfil the scientific requirements. The Radio Frequency system upgrade has started with the replacement of the booster klystron-based transmitter by high power solid state amplifiers, and the development of HOM damped cavities operating at room temperature. A completely new DC-AC orbit stabilization system using 224 BPMs and 96 orbit steerers is currently being commissioned. The upgrade is conducted while keeping, and even improving, routine performance for the user service. In particular the recent installation of new skew quadrupole power supplies allows routine operation with ultra low vertical emittance. This paper reports on the present operation performance of the source, highlighting recent developments and those still to come.  
 
THPC023 Third Generation Light Source Project in Iran dipole, booster, lattice, radiation 2954
 
  • J. Rahighi, E. Salimi, R. safian
    IPM, Tehran, Iran
  • M. Jafarzadeh, Kh.S. Sarhadi
    ILSF, Tehran, Iran
 
  The Institute for Research in Fundamental Sciences (IPM) is in charge of the establishing the Iranian Light Synchrotron Source Facility (ILSF). This facility will be a 3rd generation 3 GeV storage ring with a circumference of roughly 300 m. The injector will consist of a 150 MeV Linac and a full energy booster synchrotron. The storage ring has a four-fold symmetry with 4 long (7.88m), 16 medium (4.0 m) and 12 short (2.8 m) straight sections. Within the medium straight section there are mini beta values in order to get an optimized flux density for the users. The emittance is in the range of 3 nmrad. The booster synchrotron has a circumference of roughly 192 m with an emittance of roughly 31 nmrad. It is a separated function machine in order to have the maximum flexibility. For both machine it is foreseen to use a 500 MHZ RF-system with normal conducting cavities. The machine will be build in an international collaboration, in which the main components have to be supplied from international market. The conceptual design report should be finished in 2012, the commissioning of the machine is expected to be in 2020.  
 
THPC024 Lattice Candidates for the ILSF Storage Ring storage-ring, lattice, dipole, synchrotron 2957
 
  • H. Ghasem
    IPM, Tehran, Iran
  • D. Einfeld
    CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
  • F. Saeidi
    ILSF, Tehran, Iran
 
  Iranian Light Source Facility (ILSF) is a new third generation synchrotron light source which is currently in design and will build in Iran. It will provide a high photon flux density to cover requirements of experimental science in several fields. Regarding to the proposed budget and in order to produce high quality X-ray pulses with several photon beamlines as a request of users, it is decided to design a very low emittance (ε<5nm-rad) storage ring with a typical beam intensity of 400 mA and circumference in the range of 280 m to 320 m. A number of design options with different lattice structure types, circumferences, etc., are explored and we present two designed lattice candidates of the ILSF storage ring. The associated Accelerator Physics issues are discussed.  
 
THPC026 Low Momentum Compaction Optics for Elettra optics, lattice, quadrupole, sextupole 2963
 
  • E. Karantzoulis, A. Carniel, S. Krecic
    ELETTRA, Basovizza, Italy
 
  The DBA optics lattice of Elettra, the third generation Italian light source is closer to DBA minimum emittance condition than any other similar lattice. At the same time, although the lattice is also optimized for large acceptance, it is very inflexible to any changes like the reduction of the momentum compaction (very desirable to the IR and SR-FEL beam lines). Nevertheless a solution has been found and consists in abandoning the achromat condition and reversing the polarity of some quadrupole and sextupole families. This special optics and its applications to Elettra are presented and discussed.  
 
THPC029 Ultra-low Emittance Light Source Storage Ring Consisting of 5-Bend Achromat Cells with Four Long Straight Sections lattice, undulator, storage-ring, wiggler 2972
 
  • K. Tsumaki
    JASRI/SPring-8, Hyogo-ken, Japan
 
  The 6 GeV ultimate storage ring (USR) consisting of ten bend achromat cells has been proposed* and applied it to the SPring-8 Storage ring**. It has the same circumference as the SPring-8 storage ring, but does not have four long straight sections, where the SPring-8 storage ring does. The cell length is twice of that of the SPring-8 storage ring and the number of cell is half of the SPring-8. The photon beam line positions would deviate from those of the existing one. To avoid these problems, we designed a storage ring that has four long straight sections and same cell number. The cell is changed from ten bend achromat to five bend achromat and the cell length is shortened to 30 m which is the same length of the SPring-8 storage ring unit cell. The total ring consists of 44 five bend achromat cells and four long straight section cells. The emittance is 104 pm and it will reduce to less than 50 pm by radiation damping of wigglers and undulators. The brightness is expected to be more than 1022 phs/s/mm2/mrad2 in 0.1%BW with 200 mA beam current.
* K. Tsumaki, N. Kumagai, NIM A 565 (2006) 394.
** K. Tsumaki, N. Kumagai, Proc. of EPAC06, THPLS035, p. 3362 (2006).
 
 
THPC030 Design of a BeamTransport Line from the SACLA Linac to the SPring-8 Storage Ring lattice, linac, beam-transport, storage-ring 2975
 
  • K. Tsumaki, K. Fukami, T. Watanabe
    JASRI/SPring-8, Hyogo-ken, Japan
  • S. Itakura, N. Kumagai
    RIKEN/SPring-8, Hyogo, Japan
 
  The SPring-8 Angstrom Compact Free Electron Laser (SACLA) linac has high beam qualities. The normalized emittance is less than 1 mm.mrad and the bunch length is less than 100 fs. If this high quality beam is injected to the SPring-8 storage ring, many interesting experiments can be done. On the other hand, the upgrade of the SPring-8 storage ring is under contemplation. The dynamic aperture of the new storage ring is expected to be so small that the small emittance beam is required to keep high beam injection efficiency. The SACLA linac beam also fulfills this requirement. For these reasons, it was decided to connect the SACLA linac and the SPring-8 storage ring. Since there is already an injection transport line from the SPring-8 synchrotron to the storage ring, the new transport line from the linac to this transport line has been constructed*. We designed the three types of magnet lattice for the new transport line; FODO, Double Bend Achromat and Triple Bend Achromat lattice. Emittance growth and bunch lengthening are calculated for each lattice and the beam qualities are compared. In this paper, lattice design and the comparison of the beam quality for each lattice are described.
* C. Mitsuda et al., this conference.
 
 
THPC032 Current Status of SPring-8 Upgrade Plan lattice, electron, brilliance, injection 2981
 
  • T. Watanabe, T. Asaka, H. Dewa, H. Ego, T. Fujita, K. Fukami, M. Masaki, C. Mitsuda, A. Mochihashi, T. Nakamura, H. Ohkuma, Y. Okayasu, Y. Shimosaki, K. Soutome, M. Takao
    JASRI/SPring-8, Hyogo-ken, Japan
  • T. Tanaka
    RIKEN Spring-8 Harima, Hyogo, Japan
 
  The SPring-8 upgrade plan has been discussed. The main goal is to replace the storage ring in the existing tunnel so that the resulting emittance will get as close to the diffraction limit in hard x-ray region as possible. For 10 keV photons, for instance, the diffraction limit corresponds to the emittance of as small as 10 pm.rad. For the challenging goal, the new ring features a multi-bend lattice with damping wigglers, which presumably enables us to reduce an emittance by two orders of magnitudes or more compared with the current double-bend lattice without damping wigglers. Up to now, a six-bend lattice has been mainly studied, which is supposed to generate a natural emittance of 60–70 pm.rad for 6 GeV. In addition, damping wigglers and coupling control should assist to reduce the emittance even more for approaching the ultimate goal. The major modification requires not only an advanced lattice design via manipulation of non-linear beam dynamics but also extensive technological developments in almost every component such as magnets, monitors, and RF systems. The overall review of the upgrade plan, including some detailed discussions on the critical issues, will be presented.  
 
THPC045 Design of a Compact Storage Ring for the TTX cavity, injection, kicker, scattering 3005
 
  • H.S. Xu, W.-H. Huang, C.-X. Tang
    TUB, Beijing, People's Republic of China
  • S.-Y. Lee
    IUCEEM, Bloomington, Indiana, USA
 
  We study a compact storage ring with circumference 3-m, 4 dipoles, and two quadrupoles for the Tsinghua Thomson scattering X-ray (TTX) source. The effects of Touschek lifetime, rf system requirement, the Intra-beam scattering (IBS) and coherent synchrotron radiation (CSR) will be addressed. A top-up injection system will be designed to maximize the Photon flux. Conceptual laser cavity to enhance photon flux will be discussed. Expected performance of the compact X-ray source will be presented.  
 
THPC057 Operation of the ALBA Injector linac, booster, injection, storage-ring 3023
 
  • M. Pont, U. Iriso, R. Muñoz Horta, F. Pérez
    CELLS-ALBA Synchrotron, Cerdanyola del Vallès, Spain
 
  The ALBA injector made of a 100 MeV linac, operating at 110 MeV, and a full energy (3 GeV) booster synchrotron has been routinely in operation since October 2010. The stability of the linac and of the booster on reliability and performance is examined. Also results on the beam performance obtained with the installed diagnostic equipment will be discussed.  
 
THPC058 The MAX IV Synchrotron Light Source linac, lattice, storage-ring, vacuum 3026
 
  • M. Eriksson, J. Ahlbäck, Å. Andersson, M.A.G. Johansson, D. Kumbaro, S.C. Leemann, 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
 
  The MAX IV synchrotron radiation facility is currently being constructed in Lund, Sweden. It consists of a 3 GeV linac injector and 2 storage rings operated at 1.5 and 3 GeV respectively. The linac injector will also be used for the generation of short X-ray pulses. The three machines mentioned above will be descibed with some emphasis on the effort to create a very small emittance in the 3 GeV ring. Some unconventional technical solutions will also be presented.  
 
THPC062 SLS Vertical Emittance Tuning alignment, quadrupole, coupling, betatron 3035
 
  • M. Böge, M. Aiba, N. Milas, A. Streun
    PSI, Villigen, Switzerland
  • S.M. Liuzzo
    INFN/LNF, Frascati (Roma), Italy
 
  To establish ultra-small vertical emittances (<1pmrad @2.86GeV) is one important aim of future linear collider damping ring optimization studies* at the SLS. By utilizing various correction techniques the SLS is already close to this goal with emittances of <2pm.rad @2.4GeV under the constraint of maintaining user operation conditions. One of the limiting contributions is the remaining spurious vertical dispersion etay of ~1.4mm which can be reduced by careful re-alignment and the application of dispersion-free steering techniques. The latter require orbit manipulations which are only partially compatible with the user operation mode. A first application of dispersion-free steering techniques demonstrates that etay can be reduced to <1mm at the expense of large orbit excursions which require a simultaneous betatron-coupling correction by means of skew quadrupoles in order to benefit in terms of a further reduction of vertical emittance. Therefore possible girder and magnet misalignments are analyzed in simulation which allows to localize the sources of etay and to eliminate them by re-alignment. Following this path the goal to achieve emittances close to 1pmrad is within reach.
* In January 2011 the EU-project TIARA (Test Infrastructure and Accelerator Research Area) started with contributions from the SLS as part of the SVET (SLS Vertical Emittance Tuning) work package WP6.
 
 
THPC064 Design Study of Low Emittance Lattice for Taiwan Light Source at 1 GeV lattice, storage-ring, dynamic-aperture, wiggler 3041
 
  • C.Y. Lee
    NTHU, Hsinchu, Taiwan
  • C.C. Chiang, P.J. Chou
    NSRRC, Hsinchu, Taiwan
  • S.-Y. Lee
    IUCEEM, Bloomington, Indiana, USA
 
  We explored the possibility that the existing TLS storage ring to be operated at 1 GeV as a high brightness VUV light source after the completion of 3 GeV Taiwan Photon Source. To increase the spectral brightness, we need to reduce the beam emittance in the storage ring as much as possible. We first pursue the lowest emittance which is possible without altering the existing hardware configuration. The theoretical minimum emittance that could be achieved at 1 GeV for non-achromatic lattice is 3.8 nm-rad. However, this could not be achieved without introducing harmonic sextupoles. Preliminary results of low emittance lattice without harmonic sextupoles in TLS storage ring will be presented.  
 
THPC066 A Study of Emittance Growth in a Photoinjector Linac by using PWT as Pre-accelerator linac, booster, solenoid, focusing 3044
 
  • A. Sadeghipanah, S.B. Hung, W.K. Lau, A.P. Lee
    NSRRC, Hsinchu, Taiwan
  • N.Y. Huang
    NTHU, Hsinchu, Taiwan
 
  The NSRRC high brightness photoinjector for light source R&D is a 2998 MHz split configuration. Our goal is to produce 1 nC bunch charge from a photo-cathode rf gun with normalized emittance of 1 mm-mrad or less. However, limited by the available power from our klystron, previous studies showed that our linac has to be equipped with focusing solenoid to help emittance control during acceleration. In order to omit the bulky focusing solenoid from the booster linac system, we considered to use two high gradient (~26 MV/m) PWT standing-wave structures to accelerate the beam previous to the linac. Studies showed that this configuration can keep the emittance as low as 1 mm-mrad while also decreasing the energy spread to half of its initial amount. The only drawback is the growth of final beam radius, which can be compensated by using a setting of quadrupole magnets.  
 
THPC067 Tolerance Studies of the Max-IV Linac linac, quadrupole, dipole, sextupole 3047
 
  • P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • D. Angal-Kalinin, J.K. Jones, P.H. Williams
    Cockcroft Institute, Warrington, Cheshire, United Kingdom
  • M. Eriksson, S. Thorin, S. Werin
    MAX-lab, Lund, Sweden
 
  The MAX IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF) and an FEL (in phase 2). We briefly describe the layout, optics and bunch compression / linearization scheme of the linac. We then investigate the robustness of the design to element errors.  
 
THPC073 Study of Lower Emittance Lattices for SPEAR3 lattice, dynamic-aperture, sextupole, injection 3062
 
  • X. Huang, Y. Nosochkov, J.A. Safranek, L. Wang
    SLAC, Menlo Park, California, USA
 
  We study paths to significantly reduce the emittance of the SPEAR3 storage ring. Lattice possibilities are explored with the GLASS technique. New lattices are designed and optimized for practical dynamic aperture and beam lifetime. Various techniques are employed to optimize the nonlinear dynamics, including the Elegant-based genetic algorithm. Experimental studies are also carried out on the ring to validate the lattice design.  
 
THPC075 Lattice Design for PEP-X Ultimate Storage Ring Light Source wiggler, lattice, dipole, dynamic-aperture 3068
 
  • Y. Nosochkov, K.L.F. Bane, Y. Cai, R.O. Hettel, M.-H. Wang
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by the Department of Energy Contract DE-AC02-76SF00515.
SLAC expertise in designing and operating high current storage rings and the availability of the 2.2-km PEP-II tunnel present an opportunity for building a next generation light source – PEP-X – that would replace the SPEAR3 storage ring in the future. The "baseline" design for PEP-X, with 164 pm-rad emittance at 4.5 GeV beam energy and a current of 1.5 A, was completed in 2010. As a next step in the study, a so-called "ultimate" PEP-X lattice having another order of magnitude reduction in emittance from the baseline design has been investigated. The beam emittance approaches the diffraction limited photon emittance for multi-keV photons, providing near maximum photon brightness and high coherence. In this design, the ring arcs contain seven-bend achromat cells yielding 29 pm-rad natural emittance and up to 9 insertion device straights per arc. Another factor of two emittance reduction is achieved with an 89.3-m damping wiggler installed in one of the six long straights. Details of the lattice design, the sextupole correction scheme, dynamic aperture simulations, and calculation of the intra-beam scattering effect and Touschek lifetime at a nominal 200-mA current are presented.
 
 
THPC082 Properties of the Radiation from the European X-ray Free Electron Laser electron, FEL, undulator, radiation 3083
 
  • E. Schneidmiller, M.V. Yurkov
    DESY, Hamburg, Germany
 
  Recent success of the Linac Coherent Light Source (LCLS) demonstrated feasibility for reliable production, compression, and acceleration of electron beams with emittances significantly smaller than original baseline parameters. The same scenario can be applied to the European XFEL as well. Experimental results from the Photo Injector Test Facility in Zeuthen (PITZ) demonstrated the possibility to generate electron beams with small charge and emittance. Computer modeling of the beam formation system also indicate on the possibility to preserve electron beam quality during acceleration and compression. Recently these trends have been analyzed, and baseline parameters of the European XFEL have been revised. Parameter space has been significantly extended in terms of the bunch charge. As a result, different modes of FEL operation become possible with essentially different properties of the radiation. In this paper we present an overview of radiation properties of SASE FEL radiators driven by electron beam with new baseline parameters.  
 
THPC088 Performance of RF System for XFEL/SPring-8 Injector cavity, gun, electron, klystron 3101
 
  • T. Asaka
    RIKEN SPring-8 Center, Sayo-cho, Sayo-gun, Hyogo, Japan
  • T. Asaka, H. Ego, H. Hanaki, T. Kobayashi, S. Suzuki, T. Taniuchi
    JASRI/SPring-8, Hyogo-ken, Japan
  • T. Inagaki
    RIKEN/SPring-8, Hyogo, Japan
  • Y. Otake, T. Shintake, K. Togawa
    RIKEN Spring-8 Harima, Hyogo, Japan
 
  In the XFEL/SPring-8 accelerator, the RF processing of an injector for the 8-GeV accelerator were carried out during two months after the installation of all the main components of the accelerator was completed in January 2011. To realize stable bunch compression process without the emittance growth, the injector adopts the combination of an extremely low emittance thermionic gun and multi-stage RF cavities for velocity bunching. In addition, in order to reduce the emittance growth occurring at the transition from the velocity bunching to acceleration, the newly developed L-band APS type accelerating structures and a waveguide system were introduced in the injector. Since an intensity of beam current is affected by the slight variations of RF power and phase of these RF equipment, we have carried out thorough countermeasures to complete highly-stabilized RF systems. Consequently, the stability of RF power and phase in rated operating condition of each RF cavity achieved 20 ppm (std.) and 0.06˚ (std.), respectively. In this paper, we describe the stability performances and RF processing of these RF systems in the injector.  
 
THPC093 Beam Dynamics Simulations for the SwissFEL Injector Test facility laser, solenoid, simulation, gun 3107
 
  • S. Bettoni, M. Pedrozzi, S. Reiche, T. Schietinger
    PSI, Villigen, Switzerland
 
  The SwissFEL under study at PSI will produce 0.1 nm to 0.7 nm wavelength coherent x-ray. The design of the injector is based on the invariant envelope matching scheme, developed for other photoinjectors in the past years. According to this technique the emittance at the exit of the injector can be minimized if some conditions at the entrance of the booster are satisfied. A campaign of simulations has been carried out to verify the impact of the errors of the machine components (RF and magnetic) and laser shaping (transverse and longitudinal) on the final SwissFEL injector emittance. These results have to be used to define the tolerances on the machine and laser.  
 
THPC095 Commissioning Status of the SwissFEL Injector Test Facility laser, solenoid, gun, electron 3110
 
  • T. Schietinger, M. Aiba, S. Bettoni, B. Beutner, A. Falone, R. Ganter, R. Ischebeck, F. Le Pimpec, N. Milas, G.L. Orlandi, M. Pedrozzi, E. Prat, S. Reiche, C. Vicario
    PSI, Villigen, Switzerland
 
  The SwissFEL injector test facility at the Paul Scherrer Institute has been in operation since August 2010. Its primary goal is the demonstration of a high-brightness electron beam as it will be required to drive the SwissFEL main linac. The injector further serves as a platform for the development and validation of accelerator components needed for the SwissFEL project. We give an overview of recent commissioning activities at about 130 MeV beam energy, with particular emphasis on results from optics matching studies and emittance measurements, the latter obtained with different optics-based methods. A five-cell transverse-deflecting cavity allows studies of the longitudinal bunch charge distribution and slice emittance. Bunch length measurements will become the focus of interest after the installation of a magnetic compression chicane, currently scheduled for the summer of 2011.  
 
THPC097 Transverse Alignment Tolerances for the European XFEL Laser Heater laser, electron, FEL, undulator 3116
 
  • V.A. Goryashko
    NASU/IRE, Kharkov, Ukraine
  • M. Dohlus
    DESY, Hamburg, Germany
  • M. Hamberg, V.G. Ziemann
    Uppsala University, Uppsala, Sweden
 
  Funding: Supported by the KTH-SU-UU FEL Center.
We study the impact of misalignments between a laser beam and an electron bunch on the energy distribution function of the electron bunch in the laser heater. Transverse position and angular misalignment as well as different spot size of the laser and electron beam are considered. We find that the transverse misalignment makes the energy distribution function narrower compared to the case of ideal adjustment and a distinct peak in the distribution around the initial mean value of the energy appears. We demonstrate that despite these misalignments a uniform heating in terms of the energy spread can be achieved by appropriately adapting the transverse size and power of the laser beam such that the energy distribution function of the electron bunch at the end of the laser heater can be made similar to a Gaussian, thus providing more effective Landau damping against the micro-bunching instability. The laser power mainly determines the local energy spread while the laser spot size governs the shape of the energy distribution function. The transverse oscillations of electrons induced by the magnetic field in the laser heater are found to be non-essential for typical operation parameters.
 
 
THPC102 Production of Coherent Optical \vCerenkov Radiation in Silica Aerogel radiation, electron, scattering, photon 3125
 
  • F.H. O'Shea, J.B. Rosenzweig
    UCLA, Los Angeles, California, USA
 
  As a demonstration of the apposite properties of silica aerogel as an electron beam diagnostic we intend to use it to produce coherent optical Cˇ erenkov radation (COCR). In this paper we propose an experiment and provide details of the challenges to be overcome in producing COCR.  
 
THPC108 Commissioning of the 50 MeV Preinjector Linac for the BESSY II Facility linac, booster, radiation, injection 3140
 
  • T. Atkinson, M. Helmecke, D. Schüler, E. Weihreter
    HZB, Berlin, Germany
  • V. Dürr
    BESSY GmbH, Berlin, Germany
  • D. Jousse, J.-L. Pastre, A.S. Setty
    THALES, Colombes, France
 
  A turn key 50MeV linac manufactured by Thales has been installed in the BESSY II facility. This linac will replace the existing Microtron injector in the near future to provide more flexible bunch population patterns for the femto-slicing operation mode and a higher single bunch intensity for top-up injection. This paper describes the essential problems which have been faced during commissioning and presents the main results obtained in the site acceptance tests including the measurement of beam emittance and energy spread.  
 
THPC113 Slice Emittance Measurements for Different Bunch Charges at PITZ laser, solenoid, electron, booster 3149
 
  • Ye. Ivanisenko, H.-J. Grabosch, M. Gross, L. Hakobyan, G. Klemz, M. Krasilnikov, M. Mahgoub, D. Malyutin, A. Oppelt, M. Otevřel, B. Petrosyan, D. Richter, S. Rimjaem, A. Shapovalov, F. Stephan, G. Vashchenko, S. Weidinger
    DESY Zeuthen, Zeuthen, Germany
  • G. Asova
    INRNE, Sofia, Bulgaria
  • I.I. Isaev
    MEPhI, Moscow, Russia
  • M.A. Khojoyan
    YerPhI, Yerevan, Armenia
  • I.H. Templin, I. Will
    MBI, Berlin, Germany
 
  The successful operation of the Free electron LASer in Hamburg (FLASH) at DESY brings up the interest in further broadening the spectrum of possible applications also for the upcoming European XFEL. Hence the electron beam properties required for lasing should be tested and optimized for a broad range of values already on the level of the injector. The Photo Injector Test facility in Zeuthen (PITZ) at DESY characterizes the photo injectors for FLASH and the European XFEL. The main study involves the transverse projected emittance optimization for different beam conditions. Beside the projected emittance, the PITZ setup allows to measure the transverse emittance with a sub-bunch longitudinal resolution. This slice emittance diagnostics is based on the usage of bunches with an energy correlation of the longitudinal phase space components induced by the booster. Then the bunch is swept vertically with a dipole magnet. Part of the bunch that corresponds to a longitudinal slice is cut out by means of a vertical slit and the horizontal emittance is measured. This report presents the results of recent slice emittance measurements for different bunch charges.  
 
THPC114 High Brightness Photo Injector Upgrade and Experimental Optimization at PITZ laser, electron, gun, booster 3152
 
  • M. Krasilnikov, H.-J. Grabosch, M. Gross, Ye. Ivanisenko, G. Klemz, W. Köhler, M. Mahgoub, D. Malyutin, A. Oppelt, M. Otevřel, B. Petrosyan, S. Rimjaem, F. Stephan, G. Vashchenko, S. Weidinger, R.W. Wenndorff
    DESY Zeuthen, Zeuthen, Germany
  • G. Asova
    INRNE, Sofia, Bulgaria
  • L. Hakobyan, M.A. Khojoyan
    YerPhI, Yerevan, Armenia
  • M. Hoffmann, H. Schlarb
    DESY, Hamburg, Germany
  • I.I. Isaev, A. Shapovalov
    MEPhI, Moscow, Russia
  • M.A. Nozdrin
    JINR, Dubna, Moscow Region, Russia
  • D. Richter
    HZB, Berlin, Germany
  • I.H. Templin, I. Will
    MBI, Berlin, Germany
 
  The photo injector test facility at DESY in Zeuthen (PITZ) develops and optimizes electron sources for linac driven free electron lasers. The main goal of PITZ is to demonstrate a small electron beam emittance by tuning several main parameters of the injector - photo cathode laser pulse, rf gun with solenoids and booster cavity parameters. A slit scan technique is used to measure the transverse phase space of the electron beam and the projected normalized emittance. The photo injector is capable of pulse train production which can be measured with dedicated diagnostics at PITZ. This enables optimization of the beam emittance for a wide range of bunch charges from tens of pC to several nC while keeping high resolution of beam measurements. The results of the experimental optimization will be presented yielding a new benchmark of photo injector performance.  
 
THPC115 Emittance Optimization for Different Bunch Charges with Upgraded Setup at PITZ laser, gun, booster, electron 3155
 
  • G. Vashchenko, G. Asova, M. Gross, L. Hakobyan, I.I. Isaev, Ye. Ivanisenko, M.A. Khojoyan, M. Krasilnikov, M. Mahgoub, D. Malyutin, M. Otevřel, B. Petrosyan, S. Rimjaem, A. Shapovalov, F. Stephan, S. Weidinger
    DESY Zeuthen, Zeuthen, Germany
  • M.A. Nozdrin
    JINR, Dubna, Moscow Region, Russia
  • D. Richter
    HZB, Berlin, Germany
  • I.H. Templin, I. Will
    MBI, Berlin, Germany
 
  The Photo Injector Test facility at DESY, Zeuthen site, (PITZ) has the aim to develop and optimize high brightness electron sources for Free Electron Lasers like FLASH and the European XFEL. Photo electrons emitted from the Cs2Te cathode are accelerated by a 1.6-cell L-band RF gun cavity operated at 60 MV/m maximum accelerating gradient at the cathode. Cylindrically shaped laser pulses with a flat-top temporal profile of about 20 ps FWHM and 2 ps rise and fall time are used to produce electron beams with extremely low emittance. The PITZ beam line was upgraded in 2010. The new gun cavity (prototype number 4.1) was installed January 2010. The new booster cavity (CDS) with well-defined field distribution was installed in July 2010. The diagnostic system for characterization of the laser hitting the photocathode was upgraded in October 2010. Emittance measurements results for different charges: 2 nC, 1 nC, 0.25 nC, 0.1 nC and 0.02 nC, will be presented. The optimization was done for different parameters, e.g. gun solenoid current, gun phase, laser spot size on the cathode, booster gradient.  
 
THPC120 Experimental Investigation of Photocathode Thermal Emittance Components with a Copper Cathode* cathode, gun, laser, electron 3167
 
  • H.J. Qian, Y.-C. Du, Hua, J.F. Hua, W.-H. Huang, C. Li, C.-X. Tang, L.X. Yan
    TUB, Beijing, People's Republic of China
 
  With progress of photocathode RF gun technology, thermal emittance has become the primary limitation of electron beam brightness*. Extensive efforts have been devoted to study thermal emittance, but experiment results diverge between research groups and few can be well interpreted**. One possibility is the undefined online cathode surface conditions, which may cause difference of work functions, field enhancement factor and surface roughness, and lead to thermal emittance divergence. In this paper, we report an experiment of characterizing online photocathode work function, field enhancement factor and surface roughness effect by measuring electric field dependence of photoemission quantum efficiency (QE) and thermal emittance in a Cu-cathode RF gun. Preliminary experiment results reveal huge thermal emittance contributed by surface roughness for the first time, and are in reasonable consistency with theoretical model prediction***.
*Ivan V. Bazarov et al., Phys. Rev. Lett. 102, 104801(2009)
** D.H. Dowell et al, Nucl. Instrum. Methods Phys. Res., Sect. A 622, 685 (2010).
***D. Xinag et al, PAC’07, 1049 (2007)
 
 
THPC121 Design and Cold Tests of a Prototype photocathode RF Gun for Shanghai SXFEL Facility gun, cathode, coupling, vacuum 3170
 
  • H.J. Qian, H. Chen, Y.-C. Du, W.-H. Huang, C. Li, X.H. Liu, X. H. Lu, C.-X. Tang
    TUB, Beijing, People's Republic of China
 
  A soft X-ray (~9 nm) FEL (SXFEL) facility is going to be constructed in Shanghai, China, which requires high charge (>500 pC) electron beam with low transverse emittance (<1.5 mm-mrad) at photoinjector exit. One of the keys to achieve a low emittance with high charge is high gradient on the photocathode, so an S-band photocathode RF gun modified from BNL type gun is designed, which aims running 100 MV/m peak gradient at 10 Hz. By changing the cathode seal technique, removing the insertion RF tuner, and reducing the peak surface field, RF breakdown possibility is reduced. Besides, RF pulse width is also considered to be reduced to lower the RF breakdown possibility. Since zero mode and multipole field degrades the beam emittance, they are also suppressed in the new gun design. Design details and cold testing results are presented in this paper.  
 
THPC125 Study of some Design Concepts and Collective Effects in the MAX IV Linac linac, simulation, sextupole, wakefield 3176
 
  • F. Curbis, M. Eriksson, O.E. Karlberg, S. Thorin, S. Werin
    MAX-lab, Lund, Sweden
  • D. Angal-Kalinin, P.H. Williams
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  The MAX IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF) and an FEL (phase 2). Compression is done in two double achromats with positive R56. The natural second order momentum compaction, T566, from the achromats is used together with weak sextupoles to linearise longitudinal phase space, leaving no need for a harmonic cavity for linearization of longitudinal phase space. In this proceeding we present the design of the achromat compressors and results from particle tracking through the MAX IV linac in high brightness mode. We also investigate emittance dilution due to CSR, in the achromat compressors, and transverse wakefields in a high beta function lattice.  
 
THPC126 RF Gun Studies for the SwissFEL Injector gun, laser, solenoid, cathode 3179
 
  • A. Falone, A. Adelmann, J.-Y. Raguin, L. Stingelin
    PSI, Villigen, Switzerland
 
  The Paul Scherrer Institut (PSI) is planning a compact, high brightness hard X-ray free electron laser. For this purpose a new 2.5 cell RF gun has been designed at PSI and is now in production. The RF gun plays an important role in preserving beam emittance, and hence delivers a high quality beam to the injector. We present beam dynamic parametric studies on the effect of cell length variations using two different codes OPAL and ASTRA. Furthermore laser and other RF parameters are scanned to find the best working point of the injector. The simulations are showing that the SwissFEL injector requirements (ϵ<0.4 mm mrad normalized projected emittance) are achievable with a smooth dependence on the geometrical variation of the gun cell lengths confirming a robust RF design of the gun is possible.  
 
THPC127 Recent Results from a Combined Diode-RF Gun cathode, electron, laser, gun 3182
 
  • C.H. Gough, S. Ivkovic, M. Paraliev
    PSI, Villigen, Switzerland
 
  For the SwissFEL project, a novel combined diode-RF electron gun was tested at PSI, as a possible source for XFELs. Typically, electron bunches of 1-100 pC charge , 1-5 MeV energy and 2-0.3 um-rad emittance were produced and measured. The advantage of the combined gun is that diode geometry and emission surface can be changed readily. An optimum polishing procedure for magnesium photo cathodes was found, and various surfaces such as FEA's were tested in high gradient. Emittance changes for emission surface depression within the cathode, as well as laser spot size and anode hole size, were measured. Finally, the excellent performance of the gun permitted detailed study of the pepperpot EMSY (Emittance Measurement System) behaviour with changing beam parameters.  
 
THPC131 MAX-IV Linac Injector Simulations including Tolerance and Jitter Analysis linac, gun, simulation, laser 3191
 
  • J.W. McKenzie, B.L. Militsyn
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
  • S. Thorin, S. Werin
    MAX-lab, Lund, Sweden
 
  The MAX-IV linac will be used both for injection and top up into two storage rings, and as a high brightness injector for a Short Pulse Facility (SPF) and an FEL (in phase 2). 100 pC bunches of electrons are created from a 1.5 cell S-band photocathode gun and subsequently accelerated up to 3 GeV by S-band linac sections. Simulations of the dynamics of the space-charge dominated beam up to 100 MeV are presented including an analysis of the tolerances required and the effects of jitter sources.  
 
THPC132 A Velocity Bunching Scheme for Creating Sub-picosecond Electron Bunches from an RF Photocathode Gun cavity, gun, solenoid, laser 3194
 
  • J.W. McKenzie, B.L. Militsyn
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire, United Kingdom
 
  Sub-picosecond electron bunches are in demand for various applications including Free Electron Lasers and electron diffraction experiments. Typically, for Free Electron Lasers, a multiple picosecond scale bunch is produced from a photoinjector with compression achieved via one or more magnetic chicanes by providing an appropriate energy chirp to the bunch in the preceding linac sections. This approach is complex, requiring many components, often including a higher harmonic linac section to linearise the longitudinal phase-space, and careful tuning in order to minimise emittance blow-up due to coherent synchrotron radiation. We present a scheme to deliver sub-picosecond electron bunches, based on a normal conducting RF gun and two short linac sections, one for providing velocity bunching and the second to capture the compressed bunch and accelerate to tens of MeV where the beam properties are then essentially frozen.  
 
THPC133 Pre-Conceptual Design Requirements For The MaRIE Facility At LANL And The Resulting X-Ray Free Electron Laser Baseline Design photon, linac, electron, scattering 3197
 
  • R.L. Sheffield, B.E. Carlsten
    LANL, Los Alamos, New Mexico, USA
 
  The MaRIE (Matter-Radiation Interactions in Extremes) facility is being proposed to advance materials science by the concurrent utilization of a diverse set of highly penetrating probes. These probes will provide the basis for developing materials that will perform predictably and on demand with currently unattainable lifetimes in extreme environments. The MaRIE facilities, the Multi-Probe Diagnostic Hall (MPDH), the Fission and Fusion Materials Facility (F3), and the Making, Measuring, and Modeling Materials (M4) Facility will each have experimental needs for one or more high-energy x-ray beam probes, but all require a 50-keV coherent source of greater than 1010 photons in less than 1 ps. Because of space considerations at the facility, a high-gradient design is being investigated that will use a X-band RF systems to drive a 20-GeV normal-conducting linac. Experimental requirements drive a need for multiple photon bunches over time durations greater than 1 microsecond, as well as interleaving 0.1 nC very-low-emittance bunches with 2-nC electron bunches. This paper will cover an overview of the scientific requirements for the MaRIE XFEL and the baseline XFEL design.  
 
THPC134 LCLS RF Gun Copper Cathode Performance cathode, laser, gun, electron 3200
 
  • A. Brachmann, F.-J. Decker, P. Emma, R.H. Iverson, P. Stefan, J.L. Turner, F. Zhou
    SLAC, Menlo Park, California, USA
 
  Funding: Work supported by Department of Energy contract DE-AC03-76SF00515
We report on the performance and the operational experience of the LCLS RF gun copper photocathodes used during the LCLS run I, II, III and IV. We discuss the problems of cathode surface contamination and our experience with methods to remove such contamination. Techniques to obtain high quantum efficiency (QE) while preserving the low emittance quality are discussed. Furthermore, we will present the current status of the installed cathode, its quantum efficiency and the typical injector emittances of the extracted beam.
 
 
THPC137 Low Emittance Booster Design for CANDLE Storage Ring booster, injection, storage-ring, synchrotron 3209
 
  • G.S. Zanyan, B. Grigoryan, K. Manukyan, A. Sargsyan, V.M. Tsakanov
    CANDLE, Yerevan, Armenia
 
  The progress in synchrotron based research made the top up operation mode of storage rings as the most attractive option both from the beam lifetime and the user points of view. To provide reliable operation of the facility at top-up injection mode the full energy low emittance new booster ring for 3 GeV CANDLE storage ring is designed. The compact synchrotron magnets with integrated quadrupole and sextupole components are used. The new design provides 20 nm emittance at the top energy with sufficient dynamic aperture and optimal optical properties at straight section for effective extraction. The complete design of the new booster and beam dynamics issues during the energy ramping are presented.  
 
THPO032 Preliminary Design of an Inductive Adder for CLIC Damping Rings kicker, damping, collider, impedance 3409
 
  • J. Holma, M.J. Barnes
    CERN, Geneva, Switzerland
 
  The Compact Linear Collider (CLIC) study is exploring the scheme for an electron-positron collider with high luminosity and a nominal centre-of-mass energy of 3 TeV. The CLIC damping rings will produce ultra-low emittance, with high bunch charge, necessary for the luminosity performance of the collider. To limit the beam emittance blow-up due to oscillations, the pulse power modulators for the damping rings kickers must provide extremely flat, high-voltage pulses: specifications call for a 160 ns duration flattop of 12.5 kV, 250 A, with a combined ripple and droop of not more than ±0.02 %. A solid-state modulator, the inductive adder, is a very promising approach to meeting the demanding specifications; this topology allows the use of both digital and analogue modulation. To effectively use modulation techniques to achieve such low ripple and droop requires an in-depth knowledge of the behaviour of the solid-state switching components and their gate drivers, as well as a good understanding of the overall circuit behaviour. This paper describes the initial design of the inductive adder.  
 
THPS001 Experimental Studies of Beam Loss during Low Energy Operation with Electron Cooled Heavy Ions in the ESR ion, bunching, space-charge, resonance 3424
 
  • P.A. Görgen, O. Boine-Frankenheim
    TEMF, TU Darmstadt, Darmstadt, Germany
  • S. Appel, C. Dimopoulou, S.A. Litvinov, M. Steck
    GSI, Darmstadt, Germany
 
  At the ESR at GSI electron cooled heavy ion beams are decelerated to 4 MeV/u and extracted for the HITRAP experiment. We will report about cooling equilibrium measurements at 4 and 30 MeV/u for Ar18+ coasting beams. We compare the equilibrium beam parameters with results from beam dynamics simulations using the BETACOOL code and an analytic model of reduced complexity. The time slot in which HITRAP accepts beam is 2μs long. For optimum efficiency the beam has to be bunched to this length before extraction. The obtained bunch profiles are compared to longitudinal beam dynamics simulations. Our measurements show that at both energies bunching leads to severe beam loss. The estimated transverse space charge tune shifts during the rf bunching indicate that resonance crossing might be responsible for the observed the beam loss. The influence of the tune shift will be further evaluated through resonance measurements.  
 
THPS004 Beam Dynamics Simulation on Simultaneous use of Stochastic Cooling and Electron Cooling with Internal Target electron, target, simulation, proton 3433
 
  • T. Kikuchi, N. Harada, T. Sasaki, H. Tamukai
    Nagaoka University of Technology, Nagaoka, Niigata, Japan
  • T. Katayama
    GSI, Darmstadt, Germany
 
  The small momentum spread of proton beam has to be realized and kept in the storage ring during the experiment with a dense internal target. The stochastic cooling alone does not compensate the momentum spread increases due to the scattering at the internal target. The dense proton beam in the six dimensional phase space includes intra-beam scattering as one of emittance growth mechanisms. The numerical simulation is carried out using Fokker-Planck equation solver, and the results on the simultaneous use of stochastic cooling and electron cooling at COSY are indicated.  
 
THPS008 Bucked Coils Lattice for the Neutrino Factory lattice, cavity, factory, betatron 3439
 
  • A. Alekou, J. Pasternak
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  • C.T. Rogers
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
 
  In the Neutrino Factory muon front end, ionization cooling is used to reduce the very large initial transverse muon beam emittance. The current baseline cooling channel, FSIIA, performs well in simulations with respect to the transmission and cooling. However, recent studies indicate the RF voltage may be limited when external magnetic field is applied and therefore, as the FSIIA lattice has a large magnetic field at the position of the RF cavities, the feasibility of FSIIA may be questioned. Bucked Coils lattice, a new cooling lattice that uses different radius and opposite polarity coils placed at the same position along the beam-axis, aims to achieve low magnetic field at the position of the RF cavities while obtaining comparable transmission to FSIIA. The detailed comparison between FSIIA and different versions of the Bucked Coils configuration with respect to the magnetic field, beam dynamics and transmission are presented in this paper.  
 
THPS017 Simulation of Hollow Beam Formation at the Initial Part of RIB Transport Channel of SPIRAL2 ion, simulation, solenoid, focusing 3457
 
  • N.Yu. Kazarinov
    JINR, Dubna, Moscow Region, Russia
  • F.R. Osswald
    IPHC, Strasbourg Cedex 2, France
 
  The initial part of Radioactive Ion Beam (RIB) transport channel of SPIRAL2 consists of 2.45 GHz ECR Ion Source, focusing solenoid, triplet of quadrupole lenses and 90-degrees analyzing bending magnet. The supporting gas (Nitrogen) current of ECRIS used in RIB production has a value about 1 mA. The influence of the Nitrogen beam self-fields may leads to hollow beam formation in the transported ion species at the part of beam line placed after the focusing solenoid. This effect increases the RIB emittance and therefore complicates the RIB transport. In this report the numerical simulation of hollow beam formation is fulfilled. The threshold current of ECRIS supporting gas which gives a hollow beam formation of transported ions is defined. The influence of the beam neutralization is taking into account. The possible neutralization factor is found from results of simulation of GANIL Test Bench. The simulation of a variant of quadrupoles focusing system of the initial part of RIB transport channel is performed. The influence of the Nitrogen beam space charge on transport of 120+ ions with energy of 60 keV is studied.  
 
THPS021 Methods to Obtain High Intensity Proton Ion Beams with Low Emittance from ECR Ion Source at Peking University ion, plasma, ion-source, extraction 3463
 
  • H.T. Ren
    Graduate University, Chinese Academy of Sciences, Beijing, People's Republic of China
  • J.E. Chen, Z.Y. Guo, P.N. Lu, S.X. Peng, Z.Z. Song, J.X. Yu, M. Zhang, J. Zhao, Q.F. Zhou
    PKU/IHIP, Beijing, People's Republic of China
 
  Funding: Supported by the National Science Foundation of China 11075008.
With the development of accelerator technology, to obtain an ion beam with high intensity and low emittance is becoming one of the main goals of research for ion sources. At Peking University we have developed several 2.45 GHz electron cyclotron resonance (ECR) ion sources for different projects and we paid close attention to the beam intensity increasing as well as the beam emittance reduction. Methods are adopted to improve beam intensity by increasing the density of plasma inside the discharge chamber, optimizing the geometry pinch effect and the perveance at the extraction aperture. To suppress the emmitance increasing of an extracted beam, the shape of the electrodes as well as the voltage of suppression electrode are carefully selected With these efforts, a 120 mA total proton beam has been extracted from the permanent magnet ECR ion source at 50 kV, and the measured normalized rms emittance is less than 0.2 pi.mm.mrad. The beam current density at the extraction aperture is about 420 mA/cm2.
 
 
THPS022 Improvement of the 20 MeV Proton Accelerator at KAERI ion-source, ion, proton, linac 3466
 
  • H.-J. Kwon, Y.-S. Cho, J.-H. Jang, D.I. Kim, H.S. Kim, K.T. Seol, Y.-G. Song
    KAERI, Daejon, Republic of Korea
 
  Funding: This work is supported by the Ministry of Science and Technology of the Korean government.
The 20 MeV proton accelerator has been operating since 2007 when it got a operational license at Korea Atomic Energy Research Institute (KAERI) by Proton Engineering Frontier Project (PEFP). A microwave ion source was newly developed to satisfy the requirement of minimum 100 hour operation time without maintenance. After the long time operation test at test bench, it was installed to drive the 20 MeV proton accelerator. The beam profile and emittance were measured to check the characteristics of the accelerator both at the LEBT and at the end of the 20 MeV DTL. In this paper, the microwave ion source is presented and the measurement results of the beam property are discussed.
 
 
THPS033 Skew Quadrupole Effects on Multi-turn injection Efficiency in the SIS18 quadrupole, septum, injection, coupling 3490
 
  • W.M. Daqa, I. Hofmann, J. Struckmeier
    GSI, Darmstadt, Germany
 
  Funding: DAAD ( Deutscher Akademischer Austausch Dienst)
One goal of the SIS18 upgrade scheme is concerned about improving the multi-turn injection (MTI) efficiency, in order to reach the required intensities at the targets and to operate effectively as a booster for SIS100. To improve the limitation of the MTI scheme, there were successful attempts in AGS and PS boosters, to use the skew injection scheme and later it was suggested for SIS18. The strength of the skew quadrupoles is optimized together with the horizontal tune, the difference in horizontal to vertical tunes, the incoming beam parameters and the geometrical limitation of SIS lattice. A good optimization implies the emittance exchange, due to linear coupling, to take place partially and just before the return of the beamlet back to its original position at the septum. The present work was done by simulation using the code PARMTRA and compared with measurements. The results show that, depending on the working point, the skew injection scheme can improve the MTI efficiency from 2% up to 12%, taking into account the loss on the septum from inside and on the vertical acceptance.
 
 
THPS044 Study of Charge Exchange Injection in HITFiL injection, ion, synchrotron, dipole 3520
 
  • W.P. Chai, J. Shi, J.W. Xia, J.C. Yang
    IMP, Lanzhou, People's Republic of China
 
  A new accelerator complex dedicated to hadron cancer therapy, Heavy-Ion Therapy Facility in Lanzhou (HITFiL), is proposed and designed. Based on the operating experience and existing technology on HIRFL-CSR, a heavy-ion cyclotron is used as an injector instead of a linac. A heavy-ion synchrotron as main component is designed with special attention paid to compact structure, high reliability and low cost. HITFiL is designed to accommodate both proton and carbon-ion using the same injecting channel but different injecting points. Charge exchange injection scheme, which is more efficient compared with single-turn injection but less costly compared with multiple multi-turn injection aided by electron-cooling, is adopted. H2+ or C5+ beams, pre-accelerated by the cyclotron, are stripped into H+ or C6+ by a carbon foil at injection point, then injected and merged into synchrotron coasting orbit. The design of the injection system is presented in this paper. The whole injection process is simulated, optimization of parameters on injecting efficiency, painting scheme and emittance growth are performed. The resulting beam distribution in phase space after injection is achieved.  
 
THPS045 Beam Emittance Measurement in the Injection Beam Line for a Cyclotron Accelerator Mass Spectrometer cyclotron, injection, extraction, ion 3523
 
  • D.G. Kim, H.-C. Bhang
    SNU, Seoul, Republic of Korea
  • J.-W. Kim
    NCC, Korea, Kyonggi, Republic of Korea
 
  Funding: This work was supported by National Research Foundation of Korea (NRF) Grant No. 20110018946, and also by World Class University project of the NRF.
A carbon beam was extracted and measured in the injection beam line built for an accelerator mass spectrometer (AMS) based on a cyclotron. The cyclotron AMS has been designed to realize a compact AMS having a mass resolving power of around 4000 for a negative 14C beam. The beam line is a prototype to ensure the capability to match the beam phase space with the acceptance of the cyclotron. The injection beam line consists of an ion source, Einzel lens, rf buncher, 90 degree dipole magnet and a beam diagnostic box with a slit system. The ion source with a hot filament is a commercial product, and all other elements were designed and built in house. Some measurement results of the beam line components as well as beam emittance will be presented.
 
 
THPS052 Studies on Transverse Painting for H Injection into the PSB injection, linac, kicker, space-charge 3544
 
  • C. Bracco, C. Carli, T. Fowler, B. Goddard, G. Gräwer, J.-B. Lallement, M. Martini, M. Scholz, W.J.M. Weterings
    CERN, Geneva, Switzerland
 
  Linac4 will inject 160 MeV H− ions in to the CERN PS Booster (PSB). This will allow to reduce space charge effects and increase beam intensity but will require a substantial upgrade of the injection region, with the implementation of a charge-exchange multi-turn injection scheme. The PSB has to provide beam to several users with different requirements in terms of beam intensity and emittance. Four kicker magnets (KSW), which are already installed in the PSB lattice, will be used to accomplish painting in the horizontal phase space to match the injected beams to the required emittances. Double linear functions, with varying slopes for each user, have been defined for the KSW generators waveforms according to detailed beam dynamic studies for all target intensities and emittances. Effect of space charge, injection offsets, dispersion and betatron mismatch have been taken into account. Preliminary studies have been carried out to evaluate how to obtain the required vertical emittance and the option of a transverse painting, also in the vertical plane, is explored.  
 
THPS055 Controlling Beamloss at Injection into the LHC injection, beam-losses, kicker, shielding 3553
 
  • B. Goddard, F. Alessio, W. Bartmann, P. Baudrenghien, V. Boccone, C. Bracco, M. Brugger, K. Cornelis, B. Dehning, A. Di Mauro, L.N. Drosdal, E.B. Holzer, W. Höfle, R. Jacobsson, V. Kain, M. Meddahi, V. Mertens, A. Nordt, J.A. Uythoven, D. Valuch, S. Weisz, E.N. del Busto
    CERN, Geneva, Switzerland
  • R. Appleby
    UMAN, Manchester, United Kingdom
 
  Losses at injection into the superconducting LHC can adversely affect the machine performance in several important ways. The high injected beam intensity and energy mean that precautions must be taken against damage and quenches, including collimators placed close to the beam in the injection regions. Clean injection is essential, to avoid spurious signals on the sensitive beam loss monitoring system which will trigger beam dumps. In addition, the use of the two injection insertions to house downstream high energy physics experiments brings constraints on permitted beam loss levels. In this paper the sources of injection beam loss are discussed together with the contributing factors and various issues experienced in the first full year of LHC operation. Simulations are compared with measurement, and the implemented and planned mitigation measures and diagnostic improvements are described. An outlook for future LHC operation is given.  
 
THPZ003 The SuperB Project: Accelerator Status and R&D feedback, luminosity, quadrupole, injection 3684
 
  • M.E. Biagini, S. Bini, R. Boni, M. Boscolo, B. Buonomo, T. Demma, E. Di Pasquale, A. Drago, L.G. Foggetta, S. Guiducci, S.M. Liuzzo, G. Mazzitelli, L. Pellegrino, M.A. Preger, P. Raimondi, U. Rotundo, C. Sanelli, M. Serio, A. Stecchi, A. Stella, S. Tomassini, M. Zobov
    INFN/LNF, Frascati (Roma), Italy
  • M.A. Baylac, O. Bourrion, J.-M. De Conto, N. Monseu, C. Vescovi
    LPSC, Grenoble, France
  • K.J. Bertsche, A. Brachmann, Y. Cai, A. Chao, M.H. Donald, R.C. Field, A.S. Fisher, D. Kharakh, A. Krasnykh, K.C. Moffeit, Y. Nosochkov, A. Novokhatski, M.T.F. Pivi, J.T. Seeman, M.K. Sullivan, S.P. Weathersby, A.W. Weidemann, U. Wienands, W. Wittmer, G. Yocky
    SLAC, Menlo Park, California, USA
  • S. Bettoni
    PSI, Villigen, Switzerland
  • A.V. Bogomyagkov, I. Koop, E.B. Levichev, S.A. Nikitin, I.N. Okunev, P.A. Piminov, D.N. Shatilov, S.V. Sinyatkin, P. Vobly
    BINP SB RAS, Novosibirsk, Russia
  • B. Bolzon, M. Esposito
    CERN, Geneva, Switzerland
  • F. Bosi
    INFN-Pisa, Pisa, Italy
  • 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
  • E. Paoloni
    University of Pisa and INFN, Pisa, Italy
  • C. Rimbault, A. Variola
    LAL, Orsay, France
  • Y. Zhang
    IHEP Beijing, Beijing, People's Republic of China
 
  The SuperB collider project has been recently approved by the Italian Government as part of the National Research Plan. SuperB is a high luminosity (1036 cm-2 s-1) asymmetric e+e collider at the Y(4S) energy. The design is based on a “large Piwinski angle and Crab Waist” scheme already successfully tested at the DAΦNE Phi-Factory in Frascati, Italy. The project combines the challenges of high luminosity colliders and state-of-the-art synchrotron light sources, with two beams (e+ at 6.7 and e- at 4.2 GeV) with extremely low emittances and small beam sizes at the Interaction Point. As unique features, the electron beam will be longitudinally polarized at the IP and the rings will be able to ramp down to collide at the tau/charm energy threshold with one tenth the luminosity. The relatively low beam currents (about 2 A) will allow for low running (power) costs compared to similar machines. The insertion of beam lines for synchrotron radiation users is the latest feature included in the design. The lattice has been recently modified to accommodate insertion devices for X-rays production. A status of the project and a description of R&D in progress will be presented.  
 
THPZ007 Lattice Design of Low Emittance and Low Beta Function at Collision Point for SuperKEKB dipole, dynamic-aperture, luminosity, lattice 3693
 
  • Y. Ohnishi, H. Koiso, A. Morita, K. Oide, H. Sugimoto
    KEK, Ibaraki, Japan
 
  Extremely low beta function at the interaction point(IP) and low emittance are necessary to achieve the design luminosity of 8x1035 cm-2 s-1 for a SuperKEKB project. The low emittance with a large Piwinski angle makes this possible with longer bunch longitudinally compared with the vertical beta function at IP. We call this Nano-beam scheme. In this scheme, a beam-beam parameter is realized to be less than 0.09 for the design luminosity. The lattice features, chromaticity corrections, and dynamic aperture are discussed in this article.  
 
THPZ011 Optimization of Chromatic Sextupoles in Electron Storage Rings Using Genetic Algorithms sextupole, dynamic-aperture, storage-ring, resonance 3705
 
  • Z. Duan
    IHEP Beijng, Beijing, People's Republic of China
  • Q. Qin
    IHEP Beijing, Beijing, People's Republic of China
 
  Funding: Work supported by National Science Foundation of China contract 10725525.
In order to suppress the head-tail instability, strong chromatic sextupoles are used in modern electron storage rings to correct large chromaticities due to small emittance or strong insertion quadrupoles to squeeze the bunch size at some places. However, the introduction of strong chromatic sextupoles also brings severe nonlinearity and might reduce dynamic aperture drastically. In the case of several sextupole families, the genetic algorithms are applied to find suitable configurations of sextupole strengths, directly maximizing dynamic aperture. A GeneRepair operator is introduced into the algorithm to correct chromaticities and optimize the dynamic aperture simultaneously in electron storage rings.
 
 
THPZ021 Effect of Coherent Synchrotron Radiation at the SuperKEKB Damping Ring vacuum, damping, linac, wakefield 3732
 
  • H. Ikeda, T. Abe, M. Kikuchi, K. Oide, K. Shibata, M. Tobiyama, D.M. Zhou
    KEK, Ibaraki, Japan
 
  The longitudinal wake field dominated by the CSR is important at the SuperKEKB damping ring. The peak of the CSR wake field is 100 times higher than those of the vacuum chamber components. We calculated the CSR effect for different vacuum chamber cross-sections, and adopted one which reduced longitudinal instability.  
 
THPZ024 Updated Design of the Italian SuperB Factory Injection System injection, linac, positron, electron 3738
 
  • S. Guiducci, M.E. Biagini, R. Boni, M.A. Preger, P. Raimondi
    INFN/LNF, Frascati (Roma), Italy
  • J. Brossard, O. Dadoun, P. Lepercq, C. Rimbault, A. Variola
    LAL, Orsay, France
  • A. Chancé
    CEA, Gif-sur-Yvette, France
  • J.T. Seeman
    SLAC, Menlo Park, California, USA
 
  The ultra high luminosity B-factory (SuperB) project of INFN requires a high performance and reliable injection system, providing electrons at 4 GeV and positrons at 7 GeV, to fulfill the very tight requirements of the collider. Due to the short beam lifetime, continuous injection of electrons and positrons in both HER and LER rings is necessary to keep the average luminosity at a high level. An updated version of the injection system, optimized at higher repetition frequency is presented. This scheme includes a polarized electron gun, a positron production scheme with electron/positron conversion at low energy 0.6 GeV, and a 1 GeV damping ring to reduce the injected emittance of the positron beam.  
 
FRXCA01 First Years Experience of LHC Beam Instrumentation feedback, beam-losses, instrumentation, luminosity 3779
 
  • O.R. Jones
    CERN, Geneva, Switzerland
 
  The LHC is equipped with a full suite of sophisticated beam instrumentation which has been essential for rapid commissioning, the safe increase in total stored beam power and the understanding of machine optics and accelerator physics phenomena. This talk will comment on all of these systems and on their contributions to the various stages of beam commissioning. It will include details on: the beam position system and its use for real-time global orbit feedback; the beam loss system and its role in machine protection; total and bunch by bunch intensity measurements; tune measurement and feedback; synchrotron light diagnostics for transverse beam size measurements, abort gap monitoring and longitudinal density measurements. Issues and problems encountered along the way will also be discussed together with the prospect for future upgrades.  
slides icon Slides FRXCA01 [7.322 MB]