Keyword: emittance
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MOI1B01 High Intensity Issues at FAIR ion, heavy-ion, synchrotron, ion-source 11
 
  • O.K. Kester
    GSI, Darmstadt, Germany
  • O.K. Kester
    IAP, Frankfurt am Main, Germany
  
  Funding: Supported by the BMBF and Helmholtz International Center for FAIR
The facility for antiproton and ion research - FAIR - will produce secondary beams of unprecedented intensities [1]. In order to produce such intense secondary beams and to provide intense beams for the CBM [2] and APPA [3] collaboration, primary heavy ion beams of highest intensities will be required. The main driver accelerator of FAIR will be the SIS100 synchrotron. The GSI heavy ion accelerator facility will be the injector of ion beams for SIS100. In order to reach the final intensities above 1011 ions per cycle, the injector chain has to be modified accordingly and the SIS100 has to be tailored to the needs. Therefore an intensity upgrade program of the GSI accelerator facility has been started, which comprises improvements of ion sources, of the injector linacs and of the heavy ion synchrotron SIS18. In addition, high energy beam transport and the SIS100 need to have a dedicated design, in order to handle beam losses. The issues of the upgrade programme and of the SIS100 design will be addressed.
[1] FAIR Green Paper- The Modularized Start Version, Oct.2009
[2] B.Friman et al.,The CBM physics Book, Series: Lecture Notes in Physics, Vol.814,2011
[3] http://www.fair-center.de/de/oeffentlichkeit/experimenteprogramm/appa-physics.html 		 
slides icon Slides MOI1B01 [15.662 MB]  
 
MOI1C01 Intense-beam Issues in CSNS and C-ADS Accelerators linac, cavity, lattice, simulation 25
 
  • S. Fu, S.X. Fang, Z. Li, J. Peng, J.Y. Tang, S. Wang, F. Yan
    IHEP, Beijing, People's Republic of China
  
  In 2011 construction of two intense-beam accelerators were launched for China Spallation Neutron Source (CSNS) project and China Accelerator Driven System (C-ADS) project. CSNS uses a pulsed accelerator with an H− linac and a rapid cycling synchrotron, and C-ADS has a CW proton linac with superconducting cavities. In both cases, the beam power is high and beam loss control is a key issue in beam dynamics. Beam emittance growth and beam halo formation must be carefully studied in beam dynamics and well controlled in machine design. This paper will present a brief introduction to the physics design of the two intense-beam accelerators, especially on the issue of beam instability. In their linac design equapartitioning focusing scheme is adopted to avoid coupling instability. Some beam halo formation experimental results due to mismatching will be compared with simulations. Beam halo generation due to the quench of superconducting cavity and magnet is investigated in detail and compensation scheme is also proposed. Beam loss study for the error effects and orbit correction will be presented.  
slides icon Slides MOI1C01 [3.747 MB]  
 
MOI1C02 Challenges in Benchmarking of Simulation Codes against Real High Intensity Accelerators simulation, space-charge, resonance, linac 30
 
  • I. Hofmann
    GSI, Darmstadt, Germany
  
  Benchmarking of simulation codes for linear or circular accelerators involves several levels of complexity, which will be revisited and discussed in this talk. As ultimate goal of benchmarking it is hoped that a predictive capacity and a practical control over emittance growth and/or beam loss can be obtained. We first give some examples of how simulation codes can be used to gain as much understanding of the underlying physics mechanisms as possible, which is an almost inevitable first step. With more and more experimental data from running high intensity accelerators having become available in recent years more questions need to be raised: Besides the proper physics, can we feed our codes with an accurate enough model of the real machine? What actually is the required accuracy, and does a specific accelerator have enough diagnostics to enable this accuracy? In the paper we explore these questions by discussing several examples of benchmarking efforts, their achievements as well as the limits and difficulties that have been encountered.  
slides icon Slides MOI1C02 [2.838 MB]  
 
MOP207 Planning for Experimental Demonstration of Transverse Emittance Transfer at the GSI UNILAC through Eigen-emittance Shaping quadrupole, coupling, simulation, scattering 57
 
  • C. Xiao, O.K. Kester
    IAP, Frankfurt am Main, Germany
  • L. Groening
    GSI, Darmstadt, Germany
  
  The minimum transverse emittances achievable in a beam line are determined by the two transverse eigen-emittances of the beam. For vanishing interplane correlations they are equal to the well-know rms-emittances. Eigen-emittances are constants of motion for all symplectic beam line elements, i.e. (even tilted) linear elements. To allow for rms-emittance transfer, the eigen-emittances must be changed by applying a non-symplectic action to the beam, preferably preserving the 4d-rms-emittance. This contribution will introduce the concept for eigen-emittance shaping and rms-emittance transfer at an ion linac. A path towards the experimental demonstration of the concept at the GSI UNILAC is presented.  
 
MOP211 1-MW Beam Operation Scenario in the J-PARC RCS injection, quadrupole, lattice, controls 68
 
  • H. Hotchi, H. Harada, N. Hayashi, M. Kinsho, P.K. Saha, Y. Shobuda, F. Tamura, K. Yamamoto, M. Yamamoto, M. Yoshimoto
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  • Y. Irie
    KEK, Ibaraki, Japan
  
  The injection energy of the J-PARC RCS will be upgraded from 181 MeV to 400 MeV in the 2013 summer-autumn period. With this upgraded injection energy, we are to aim for 1 MW design output beam power. In this paper, we discuss beam dynamics issues for the 1 MW beam operation and their possible solutions.  
 
MOP217 MEBT2 Design for the C-ADS Linac linac, focusing, space-charge, proton 93
 
  • Z. Guo, H. Geng, Z. Li, J.Y. Tang
    IHEP, Beijing, People's Republic of China
  
  The C-ADS linac is composed by two parallel injectors and a main linac, a section of Medium Energy Beam Line (MEBT2) is designed to guide and match beams from two injectors to the main linac. The two injectors are hot-spare for each other in order to satisfied the requirement of high availability and reliability. The beam in online operation mode will be directed to the main linac from one injector, while the beam in the offline mode with low repetition frequency from the other injector, will be directed to a beam dump through an auxiliary beam line. With a long drift distance and in the presence of space charge force for 10 mA 10 MeV proton beam, the debunching effect is very strong and it requires very strict control over beam losses and emittance growth. It is difficult to obtain satisfactory longitudinal matching without bunchers in the bending section. An analytical study using transfer matrix shows that with two bunchers of same voltage in the bending section the achromatism can be maintained if the effective voltage is inversely proportional to the distance between the two bunchers. It is also under consideration if and how a beam collimation can be implanted in MEBT2.  
 
MOP218 Dynamics of Particles in a Tilted Solenoidal Focusing Channel focusing, linac, solenoid, alignment 97
 
  • H. Jiang, S. Fu
    IHEP, Beijing, People's Republic of China
  
  We use the paraxial ray approximation equations to analysis the dynamics of particles in a tilted solenoidal focusing channel. In this case, the particles' initial canonical angular momentum is nonzero, so we need to add the term of centrifugal potential to the dynamics equation of particles. And in the dynamics equation this centrifugal potential term is nonlinear, which results in the emittance growth. In practice, we also need to consider the spherical aberration's effect on emittance growth and the linear part of the space-charge force of a Kapchinskij-Vladimirskij distribution beam in the dynamics equation of particles.  
 
MOP219 Error Analysis and Correction Scheme in C-ADS Injector-I linac, cavity, simulation, solenoid 99
 
  • C. Meng, Z. Li, J.Y. Tang
    IHEP, Beijing, People's Republic of China
  
  Funding: Supported by the China ADS Project (XDA03020000)
C-ADS Injector-I is a 10 mA 10 MeV CW proton linac. It uses a 3.2MeV normal conducting 4-Vane RFQ and 12 superconducting single-Spoke cavities. According to the detailed sensitivity analysis of alignment and RF errors, the error tolerance of both static and dynamic ones for Injector-I are presented. The simulation results show that with the error tolerance there are beam losses, the residual orbit is too large which will produce significant emittance growth, so the correction is necessary for Injector-I. After detailed numerical studies, a correction scheme and monitor distributions are proposed. After correction the RMS residual orbit can be controlled within 0.4mm and RMS emittance growth can be controlled within 10%, but it still has 1.7×10-6 beam loss, which comes from the RF errors and low longitudinal acceptance. According to detailed analysis and simulations with 108 macro particles, as a consequence, longitudinal emittance control and longitudinal distribution control as well as large longitudinal acceptance are the key to minimizing beam losses in low energy section. To minimize beam loss, a short period Injector-I lattice with larger longitudinal acceptance have been designed and performance very good error tolerance. 		 
 
MOP220 Local Compensation-rematch for Major Element Failures in the C-ADS Accelerator cavity, solenoid, quadrupole, focusing 102
 
  • B. Sun, Z. Li, J.Y. Tang, F. Yan
    IHEP, Beijing, People's Republic of China
  
  In order to achieve the required reliability and availability for the C-ADS accelerator, a fault tolerance design is pursued. The effects of cavity failure in different locations have been studied and the schemes of compensation by means of local compensation have been investigated. After one cavity failure, by adjusting the settings of the neighboring cavities and the focusing elements to make sure that the Twiss parameters and energy are approximately recovered to that of the nominal ones at the matching point. We find the normalized RMS emittance and emittances including 99.9% and 100% particles have no obvious growth after applying the compensation with the RMS rematching in each section of the main linac. However, the conclusions above are drawn from the simulation results with the TraceWin code, which doesn't consider the phase difference. A code based on Matlab is under developing. By applying the code on the cavity failure in the middle part of spoke021 section, a fully compensated scheme with good dynamics results is obtained. The space charge effect is still not implanted in the code, and further study and optimization of the code will be performed in the next step.  
 
MOP221 Physics Design of the C-ADS Main Linac Based on Two Different Injector Design Schemes linac, simulation, lattice, cavity 107
 
  • F. Yan, Z. Li, C. Meng, J.Y. Tang
    IHEP, Beijing, People's Republic of China
  
  Funding: Supported by Advanced Research Project of the Chinese Academy of Science
Two design schemes for the main linac of C-ADS (China Accelerator Driven Subcritical system) are presented in this paper. They are corresponding to two different injector schemes. Injector-II scheme makes use of room-temperature RFQ and superconducting HWR cavities with the RF frequency of 162.5 MHz; Injector-I scheme makes use of higher-energy RFQ and superconducting spoke cavities with the RF frequency of 325 MHz. At the first choice, a relatively smaller longitudinal emittance is adopted for the RFQ designs with both the injector schemes to obtain more efficient acceleration. However, compared with the injector-I scheme, with the injector-II scheme, bunch current will be doubled in the main linac due to the half RF frequency in the injector-II. This means stronger space charge effects. Alternate design for the main linac with the injector-II scheme is to increase the longitudinal emittance by 50% so that the space charge effects will be alleviated. However, totally 30 cavities more and 36 m longer in the main linac have to be paid for this design scheme. The design considerations, the lattice designs, the simulation results including halo information are presented. 		 
 
MOP229 Design of the MEBT1 for C-ADS Injector II quadrupole, DTL, rfq, simulation 115
 
  • H. Jia, Y. He, S.C. Huang, C.L. Luo, M.T. Song, Y.J. Yuan, X. Zhang
    IMP, Lanzhou, People's Republic of China
  
  The MEBT1 of Chinese ADS Injector II is described. It transports a 2.1 MeV, 10 mA CW proton beam through a series of 7 quadruples and two buncher cavities from the RFQ to the superconducting DTL. For emittance preservation, a compact mechanical design is required. Details of the beam dynamics and mechanical design will be given.  
 
MOP231 Study of Non-equi-partitioning Lattice Setting and IBS Effects for J-PARC Linac Upgrade lattice, linac, simulation, DTL 118
 
  • Y. Liu
    IMP, Lanzhou, People's Republic of China
  • M. Ikegami
    JAEA/J-PARC, Tokai-Mura, Naka-Gun, Ibaraki-Ken, Japan
  
  For the coming upgrade of J-Parc, the peak power of linac will be greatly increased. This may open many interesting questions. For instance, for efficient acceleration from 19 0MeV to 400 MeV the annular coupled structure (ACS) was applied with frequency jump from 324 MHz to 972 MHz. Upstream part of J-PARC linac from the frequency jump is set with the equi-partitioning (EP) condition, which prevents from the coherent resonances. If EP condition is kept for the downstream part, due to the frequency jump, the transverse focusing should also ‘jump' 3 times with shrink of envelop. The increased beam-density affects the interactions between particles, including the intra-beam stripping (IBS) effect in the H− beam. The temperature ratio between transverse and longitudinal planes is used as a knob for studying the beam behavior for the cases away from equi-partitioning. The IBS effects, as well as strategies for setting downstream non-equi-partitioning lattice due to frequency jump are studied. The matching and beam evolution in the transition section from EP to non-EP (MEBT2) are also studied. The results help to reach an optimum with least risks from resonances and IBS effects and so on.  
 
MOP232 Optimization of the Superconducting Section of Injector Ⅱ for C-ADS solenoid, simulation, lattice, linac 122
 
  • S.H. Liu, Y. He, Z.J. Wang
    IMP, Lanzhou, People's Republic of China
  
  Abstract: The China Accelerator driven System (C-ADS) project which includes a high current SC proton linac is being studied under Chinese Academy of Science. Injector II, one of parallel injectors, is undertaken by Institute of Modern Physics (IMP). The lattice design of Injector II has been done. While in most case, the elements, such as SC cavities and SC solenoids, have different weight to the final beam parameters. What is more, in the real operation process of the machine, the optimized mode is hard to find. In the paper, Latin sampling method specified in DAKOTA code combined with TRACK is adopted to build hundreds of virtual machines to analyse the sensitivity of the SC section and to find optimization operation mode.  
 
MOP233 Error and Tolerance Studies for Injector II of C-ADS linac, simulation, solenoid, alignment 125
 
  • W.S. Wang, Y. He, Z.J. Wang
    IMP, Lanzhou, People's Republic of China
  
  The proposed Chinese Accelerator Driven System (C-ADS) driver linac is being designed by Chinese Academic Science (CAS). Injector II is designed and fabricated in Institute of Modern Physics (IMP). Injector II will accelerate 10 mA proton beams to 10 MeV. Because of the high final beam power (100 kW) specified for the linac operation, beam loss must be limited to 10-5 level to avoid radiation damage. Misalignment and RF error simulation for cavities and focusing elements after RFQ were performed and the correction schemes developed using the computing code TRACK. Error and tolerance studies for Injector II are presented.  
 
MOP247 Beam Stability and Tail Population at SPS Scrapers injection, extraction, controls, diagnostics 166
 
  • L.N. Drøsdal, K. Cornelis, B. Goddard, V. Kain, M. Meddahi, O. Mete, B. Mikulec, E. Veyrunes
    CERN, Geneva, Switzerland
  
  Before injection into the LHC the beams are scraped in the SPS to remove the tails of the transverse particle distributions. Without scraping the tail population is large enough to create losses above the beam abort thresholds of the LHC beam loss monitor system when injecting. The scrapers are only effective if correctly set up. This paper shows the results of periodical scraper scans. The beam position and beam size at the scraper is changing with time. The scraper settings hence need to follow accordingly. The scans also give insight into the transverse tail population and could therefore provide useful beam quality diagnostics. The impact on new scraper designs and setting up strategy are discussed.  
 
MOP248 Brightness Evolution for LHC Beams during the 2012 Run brightness, injection, luminosity, extraction 170
 
  • M. Kuhn
    Uni HH, Hamburg, Germany
  • G. Arduini, J.F. Comblin, A. Guerrero, V. Kain, B. Mikulec, F. Roncarolo, M. Sapinski, M. Schaumann, R. Steerenberg
    CERN, Geneva, Switzerland
  
  One of the reasons for the remarkable achievements of the LHC is the excellent performance of the LHC injector chain. The evolution of the brightness in the injectors and at LHC collision in 2011 and 2012 is discussed. During certain run periods, the brightness from the beam provided by the injectors was lower than usual. Some of the issues have been identified so far and will be reported. The latest results on emittance blow-up investigations through the 2012 LHC cycle will also be presented and compared to the 2011 data. Possible implications for LHC upgrade scenarios will be mentioned.  
 
MOP249 Tune Spread Studies at Injection Energies for the CERN Proton Synchrotron Booster injection, linac, space-charge, proton 175
 
  • B. Mikulec, A. Findlay, V. Raginel, G. Rumolo, G. Sterbini
    CERN, Geneva, Switzerland
  
  In the near future, a new H− injector, Linac4, will replace the current proton injector of the CERN Proton Synchrotron Booster (PSB), Linac2. The new charge-exchange injection at 160 MeV will yield higher brightness beams compared to the conventional 50 MeV multi-turn injection of Linac2. To make full use of the higher injection energy, space-charge effects will need to be understood and mitigated to optimize the intensity versus transverse emittance reach. This includes an optimization of longitudinal acceptance and distribution with a two-harmonic rf system, careful selection of the working point to accommodate the large Laslett tune-shift of approximately -0.5 and compensation of resonances within their stopbands. This paper will present calculations of the tune spread, based on measurements of longitudinal parameters and transverse emittances, for energies up to 160 MeV, different bunch densities and varying beam intensities. It should provide valuable information on the expected tune spread after the connection of Linac4 with the PSB and input for the study of resonance compensation techniques.  
 
MOP250 Colliding High Brightness Beams in the LHC brightness, beam-beam-effects, proton, luminosity 180
 
  • T. Pieloni, X. Buffat, R. Giachino, W. Herr, E. Métral, G. Papotti
    CERN, Geneva, Switzerland
  
  The CERN-LHC is a high energy particle collider, where intense proton bunches are brought into collision. In order to achieve optimum performance, the bunches must have a high brightness, leading to strong and significant beam-beam effects. Experimental tests during the first two years of its operation have shown that beams with very high brightness can be collided head-on without detrimental effects on the beam dynamics. Such head-on collisions are therefore not expected to limit the LHC performance. Long range beam-beam interactions dominate the adverse effects on the dynamics but can profit from an increased beam brightness, in particular from small emittances. We summarize the experimental results and compare with the theoretical expectations. This allows to optimize the performance for future operation and a definition of promising upgrade scenarios.  
 
MOP252 Measurements of the LHC Longitudinal Resistive Impedance with Beam impedance, electron, synchrotron, synchrotron-radiation 183
 
  • J.F. Esteban Müller, T. Argyropoulos, T. Bohl, T. Mastoridis, N. Mounet, G. Papotti, B. Salvant, E.N. Shaposhnikova, D. Valuch
    CERN, Geneva, Switzerland
  
  The resistive part of the longitudinal impedance contributes to the heat deposition on different elements in the LHC ring including the beam screens, where it has to be absorbed by the cryogenic system and can be a practical limitation for the maximum beam intensity. In this paper, we present the first measurements of the LHC longitudinal resistive impedance with beam, done through synchronous phase shift measurements during Machine Development sessions in 2012. Synchronous phase shift is measured for different bunch intensities and lengths using the high-precision LHC Beam Phase Module and then data are post-processed to further increase the accuracy. The dependence of the energy loss per particle on bunch length is then obtained and compared with the expected values found using the LHC impedance model.  
 
MOP254 Design of a Photo-detachment Emittance Instrument for FETS laser, dipole, diagnostics, simulation 192
 
  • C. Gabor
    STFC/RAL/ASTeC, Chilton, Didcot, Oxon, United Kingdom
  • G.E. Boorman, A. Bosco
    Royal Holloway, University of London, Surrey, United Kingdom
  • A.P. Letchford
    STFC/RAL, Chilton, Didcot, Oxon, United Kingdom
  • P. Savage
    Imperial College of Science and Technology, Department of Physics, London, United Kingdom
  
  Photo detachment is a possibility to diagnose non-destructively H− ion beams. For emittance measurements, the produced neutrals are more suitable then the photo-detached electrons. Such a Photo-Detachment Emittance Measurement Instrument (PD-EMI) is planned for the Front End Test Stand (FETS) at Rutherford Appleton Laboratory (RAL/ UK). FETS comprises a Penning ion source of 60 mA beam current with up to 2 ms pulse length at 50pps, a Low Energy Beam Transport (LEBT), a four-vane RFQ with 3 MeV and a Medium Energy Beam Transport (MEBT) with a chopper system. The PD-EMI will be integrated at the end of the MEBT to commission the RFQ which is currently under construction. The introduction gives an overview some results reached so far and explains the conceptual design. Beam simulations show how to implement this to the MEBT being under construction. The remaining paper concentrates then on the hardware which is the dipole magnet, the laser and optics. The design and and engineering of the magnet chamber needs special attention to both satisfy beam transportation and diagnostics purpose. First measurements about the laser and its parameters will be presented.  
 
TUO1A01 The High Intensity/High Brightness Upgrade Program at CERN: Status and Challenges linac, injection, space-charge, extraction 226
 
  • S.S. Gilardoni, G. Arduini, T. Argyropoulos, S. Aumon, H. Bartosik, E. Benedetto, N. Biancacci, T. Bohl, J. Borburgh, C. Carli, F. Caspers, H. Damerau, J. Esteban Müller, V. Forte, R. Garoby, M. Giovannozzi, B. Goddard, S. Hancock, K. Hanke, A. Huschauer, G. Iadarola, M. Meddahi, G. Métral, B. Mikulec, E. Métral, Y. Papaphilippou, S. Persichelli, G. Rumolo, B. Salvant, F. Schmidt, E.N. Shaposhnikova, R. Steerenberg, G. Sterbini, M. Taborelli, H. Timko, M. Vretenar, R. Wasef, C. Yin Vallgren, C. Zannini
    CERN, Geneva, Switzerland
  • G. Franchetti
    GSI, Darmstadt, Germany
  • M. Migliorati
    University of Rome "La Sapienza", Rome, Italy
  • A.Y. Molodozhentsev
    J-PARC, KEK & JAEA, Ibaraki-ken, Japan
  • M.T.F. Pivi
    SLAC, Menlo Park, California, USA
  • V.G. Vaccaro
    Naples University Federico II, Mathematical, Physical and Natural Sciences Faculty, Napoli, Italy
  
  The future beam brilliance and intensities required by the HL-LHC (High-Luminosity LHC) project and for possible new neutrino production beams triggered a deep revision of the LHC injector performances. The analysis, progressing in the framework of the LHC Injectors Upgrade (LIU) projects, outlined major limitations mainly related to collective effects - space charge in PSB and PS, electron cloud driven and TMCI instabilities in the SPS, longitudinal coupled bunch instabilities in the PS for example - but also to the existing hardware capability to cope with beam instabilities and losses. A summary of the observations and simulation studies carried out so far, as well as the future ones, will be presented. The solution proposed to overcome the different limitations and the plans for their implementation will be also briefly reviewed.  
slides icon Slides TUO1A01 [12.748 MB]  
 
TUO3A01 Dynamical Aspects of Emittance Coupling in Intense Beams resonance, linac, coupling, simulation 240
 
  • I. Hofmann
    GSI, Darmstadt, Germany
  • I. Hofmann
    HIJ, Jena, Germany
  
  In this paper we study in an idealized lattice model the dynamical behavior of non-equipartitioned beams and of approach to equipartition. It is shown that emittance transfer depends on times scales of tune change, but also the direction of crossing the stopbands of space charge resonances. This provides additional information to support the stability charts suggested previously as design tool for high current linacs.  
slides icon Slides TUO3A01 [4.897 MB]  
 
TUO3A03 Equipartition, Reality or Swindle? resonance, coupling, linac, space-charge 250
 
  • J.-M. Lagniel
    GANIL, Caen, France
  
  By way of introduction to a general discussion on space-charge induced energy equipartition (EQP), the following questions will be tackled: Why the formula presently used to define EQP is wrong? Why energy exchanges can occur although the EQP rule is respected? Why safe tunings can be find although the EQP rule is not respected? Why EQP is a swindle for a large majority of our accelerated beams? Why LINAC designers nevertheless like to use the EQP rule?  
slides icon Slides TUO3A03 [1.537 MB]  
 
TUO3B01 Beam Dynamics Design of ESS Warm Linac linac, rfq, DTL, proton 274
 
  • M. Comunian, F. Grespan, A. Pisent
    INFN/LNL, Legnaro (PD), Italy
  • I. Bustinduy
    ESS Bilbao, Bilbao, Spain
  • L. Celona, S. Gammino, L. Neri
    INFN/LNS, Catania, Italy
  • R. De Prisco
    Lund University, Lund, Sweden
  • M. Eshraqi, R. Miyamoto, A. Ponton
    ESS, Lund, Sweden
  
  In the present design of the European Spallation Source (ESS) accelerator, the Warm Linac will accelerate a pulsed proton beam of 50 mA peak current from source at 0.075 MeV up to 80 MeV. Such Linac is designed to operate at 352.2 MHz, with a duty cycle of 4% (3 ms pulse length, 14 Hz repetition period).In this paper the main design choices and the beam dynamics studies for the source up to the end of DTL are shown.  
slides icon Slides TUO3B01 [17.664 MB]  
 
TUO3B02 Beam Dynamics of the ESS Superconducting Linac linac, cavity, proton, quadrupole 278
 
  • M. Eshraqi, H. Danared, R. Miyamoto
    ESS, Lund, Sweden
  
  The European Spallation Source, ESS, uses a linear accelerator to deliver the high intensity proton beam to the target station. The nominal beam power is 5 MW at an energy of 2.5 GeV. The superconducting part covers more than 95\% of the energy gain and 90\% of the length. The beam dynamics criteria applied to the design of the superconducting part of the linac including the frequency jump at a medium energy of 200 MeV as well as the beam dynamics performance of this structure are described in this paper.  
slides icon Slides TUO3B02 [4.406 MB]  
 
TUO3B03 Linac4 Beam Commissioning Strategy linac, space-charge, DTL, diagnostics 283
 
  • J.-B. Lallement, A.M. Lombardi, P.A. Posocco
    CERN, Geneva, Switzerland
  
  Linac4 is a 160 MeV H− ion linear accelerator, presently under construction, which will replace the 50 MeV Linac2 as injector of the CERN proton complex. Linac4 is a 90 m long normal-conducting Linac made of a 3 MeV Radio Frequency Quadrupole (RFQ) followed by a 50 MeV Drift Tube Linac (DTL), a 100 MeV Cell-Coupled Drift Tube Linac (CCDTL) and a Pi-Mode Structure (PIMS). Starting in 2013, five commissioning stages, interlaced with installation periods, are foreseen at the energies of 3, 12, 50, 100 and 160 MeV. In addition to the diagnostics permanently installed in the Linac, temporary measurement benches will be located at the end of each structure and will be used for beam commissioning. Comprehensive beam dynamics simulations were carried out through the Linac and the diagnostic benches to define a commissioning procedure, which is summarised in this paper. In particular, we will present a method for emittance reconstruction from profile measurements which keeps into account the effects of space charge and finite diagnostics resolution.  
slides icon Slides TUO3B03 [2.951 MB]  
 
TUO1C03 The Beam Diagnostics of CSNS diagnostics, linac, injection, neutron 302
 
  • T.G. Xu, J.N. Bai, C. Chen, L.X. Han, F. Li, P. Li, M. Meng, J.L. Sun, J.M. Tian, A.X. Wang, B. Wang, M.H. Xu, Zh.H. Xu, X.Y. Yang, L. Zeng
    IHEP, Beijing, People's Republic of China
  
  CSNS project is in the construction stage. The overview of CSNS beam diagnostics is presented which includes linac, RCS and both transport beam line. also some predevelopment of CSNS beam diagnostics is presented.  
slides icon Slides TUO1C03 [8.366 MB]  
 
TUO1C04 Detection of Unidentified Falling Objects at LHC simulation, proton, beam-losses, injection 305
 
  • E. Nebot Del Busto, T. Baer, F.V. Day, B. Dehning, E.B. Holzer, A. Lechner, R. Schmidt, J. Wenninger, C. Zamantzas, M. Zerlauth, F. Zimmermann
    CERN, Geneva, Switzerland
  • M. Hempel
    BTU, Cottbus, Germany
  
  About 3600 Ionization Chambers are located around the LHC ring to detect beam losses that could damage the equipment or quench superconducting magnets. The BLMs integrate the losses in 12 different time intervals (from 40 μs to 83.8 s) allowing for different abort thresholds depending on the duration of the loss and the beam energy. The signals are also recorded in a database at 1 Hz for offline analysis. Since the 2010 run, a limiting factor in the machine availability occurred due to unforeseen sudden losses appearing around the ring on the ms time scale. Those were detected exclusively by the BLM system and they are the result of the interaction of macro-particles, of sizes estimated to be 1-100 microns, with the proton beams. In this document we describe the techniques employed to identify such events as well as the mitigations implemented in the BLM system to avoid unnecessary LHC downtime.  
slides icon Slides TUO1C04 [6.812 MB]  
 
WEO1A04 Longitudinal Instabilities in the SPS and Beam Dynamics Issues with High Harmonic RF Systems beam-loading, synchrotron, damping, controls 358
 
  • E.N. Shaposhnikova, T. Argyropoulos, T. Bohl, J. Esteban Müller, H. Timko
    CERN, Geneva, Switzerland
  
  Even after a successful impedance reduction programme which eliminated the microwave instability in the SPS another longitudinal instability is still one of the main intensity limitations. It is observed during acceleration ramp for both single bunch and multibunch beams at intensities below the nominal LHC intensity. With the lower transition energy of the new SPS optics, under intensive studies now, the thresholds are increased. However, even in this case the operation of the 4th harmonic RF system is required for stability of the nominal beams. To cope with the higher intensity beams required for the future High Luminosity LHC an upgrade program for both RF systems is under way. The results of studies of the parameter space required for beam stability are presented and compared with operation modes of double RF systems in other accelerators.  
slides icon Slides WEO1A04 [6.135 MB]  
 
WEO1B01 Low Gamma Transition Optics for the SPS: Simulation and Experimental Results for High Brightness Beams optics, injection, electron, extraction 381
 
  • H. Bartosik, G. Arduini, T. Argyropoulos, T. Bohl, K. Cornelis, J. Esteban Müller, K.S.B. Li, Y. Papaphilippou, G. Rumolo, B. Salvant, F. Schmidt, E.N. Shaposhnikova, H. Timko
    CERN, Geneva, Switzerland
  • A.Y. Molodozhentsev
    KEK, Ibaraki, Japan
  
  The single bunch transverse mode coupling instability (TMCI) at injection is presently one of the main intensity limitation for LHC beams in the SPS. A new optics for the SPS with lower transition energy yields an almost 3-fold increase of the slip factor at injection energy and thus a significantly higher TMCI threshold, as demonstrated both in simulations and in experimental studies. It is observed furthermore that the low gamma transition optics yields better longitudinal stability throughout the entire acceleration cycle. In addition, simulations predict a higher threshold for the electron cloud driven single bunch instability, which might become an important limitation for high intensity LHC beams with the nominal 25 ns bunch spacing. This contribution gives a summary of the experimental and simulation studies, addressing also space charge effects and the achievable brightness with high intensity single bunch beams.  
 
WEO1B02 Optics Design Optimization for IBS Dominated Beams optics, scattering, ion, damping 386
 
  • F. Antoniou, H. Bartosik, Y. Papaphilippou
    CERN, Geneva, Switzerland
  • T. Demma
    LAL, Orsay, France
  • N. Milas, A. Streun
    PSI, Villigen PSI, Switzerland
  • M.T.F. Pivi
    SLAC, Menlo Park, California, USA
  
  Intra-beam scattering is a small angle multiple Coulomb scattering effect, leading to emittance growth. It becomes important for high brightness beams in low emittance lepton rings, but also hadron synchrotrons and ring colliders. Several theoretical models have been developed over the years, however, when the IBS becomes predominant, the divergence between the models becomes important. In addition, the theoretical models are based on the consideration of Gaussian beams and uncoupled transverse motion. Recently, two multi-particle tracking codes have been developed, in order to enable the understanding of the IBS influence on the beam distribution and the inclusion of coupling. The comparison between theoretical models in different lattices and different regimes is discussed here and the benchmarking of the theoretical models with the tracking codes is presented. Finally, first measurement results are presented in low emittance rings and hadron synchrotrons.  
slides icon Slides WEO1B02 [2.389 MB]  
 
WEO1B03 Circular Modes for Flat Beams in LHC optics, space-charge, luminosity, injection 391
 
  • A.V. Burov
    Fermilab, Batavia, USA
  
  Benefits and problems for operation with flat beams are discussed.  
slides icon Slides WEO1B03 [0.192 MB]  
 
WEO1B04 On Scaling Properties of Third-order Resonance Crossing in Particle Accelerators resonance, simulation, betatron, booster 394
 
  • S.-Y. Lee
    Indiana University, Bloomington, Indiana, USA
  • K.Y. Ng
    Fermilab, Batavia, USA
  
  Funding: Work supported by the US DOE under contract DEFG02-92ER40747, DE-AC02-07CH11359, and the NSF under contract PHY-0852368 with NSF.
The effects of resonances on high power hadron accelerators are explored. These resonances include systematic space-charge resonances, third-order resonance, and other weak random resonances that are often present in FFAG and other RCS accelerators. The distortion of invariant torus during resonance crossing is used to set limit on emittance growth or fraction of particle trapped. The critical resonance strength in the ring lattice is determined from a simple scaling law derived as a function of the tune-ramp rate and initial emittance. Such scaling law can be useful in the evaluation of the performance in high power accelerators. 		 
slides icon Slides WEO1B04 [1.074 MB]  
 
WEO1B05 PTC-Orbit Studies for the CERN LHC Injectors Upgrade Project booster, resonance, space-charge, injection 399
 
  • A.Y. Molodozhentsev, E. Forest
    KEK, Ibaraki, Japan
  • G. Arduini, H. Bartosik, E. Benedetto, C. Carli, M. Fitterer, V. Forte, S.S. Gilardoni, M. Martini, N. Mounet, E. Métral, F. Schmidt, R. Wasef
    CERN, Geneva, Switzerland
  
  The future improvement of the beam brilliance and intensities required in the frame of the LIU (LHC Injectors Upgrade) project to reach the demands of the HL-LHC (High-Luminosity LHC) project triggered a comprehensive study of the combined effects of the space charge and the machine resonances for the CERN synchrotrons, which are the injector chain for LHC. In frame of this report we will summarize new features of the PTC-ORBIT code which allow the beam dynamics modeling in the LHC injectors taking into account the time variation of the machine parameters during the injection process. The measurements, obtained during recent MD companies, and simulations for the low-energy high-intensity beams, will be discussed.  
slides icon Slides WEO1B05 [3.063 MB]  
 
WEO3B02 Acceleration and Transportation of Multiple Ion Species at Ebis-based Preinjector ion, rfq, linac, booster 409
 
  • D. Raparia
    BNL, Upton, Long Island, New York, USA
  
  A new heavy ion pre-injector at Brookhaven National Laboratory consist of an electron Beam Ion Source (EBIS), RFQ and IH Linac and a short transport line. This pre-injector provide any ion Helium to Uranium at energy of 2 MeV/u for Relativistic Heavy Ion Collider (RHIC) and the NASA Space Radiation Laboratory (NSRL). EBIS produces multiple charge states of an ion of interested. These charge states are accelerated through RFQ (300 keV/u) and IH Linac (2 MeV/u) and transported to booster. Charge desecration occurs just before the injection into the booster. This paper discusses implication of acceleration and transports of multiple charge state ions.  
slides icon Slides WEO3B02 [5.825 MB]  
 
WEO1C03 Longitudinal Beam Loss Studies of the CERN PS-to-SPS Transfer cavity, simulation, injection, impedance 439
 
  • H. Timko, T. Argyropoulos, T. Bohl, H. Damerau, J. Esteban Müller, S. Hancock, E.N. Shaposhnikova
    CERN, Geneva, Switzerland
  
  Bunch-to-bucket transfer between the Proton Synchrotron (PS) and the Super Proton Synchrotron (SPS) is required before beams can enter the Large Hadron Collider. The overall beam loss at this transfer is currently around 5-10 %, and is increased for higher intensities or larger longitudinal emittances. Previous attempts to reduce the losses with additional RF voltage from spare cavities in the PS were unsuccessful. In this paper, we modelled the complete PS flat-top bunch splitting and rotation manipulations, PS-to-SPS transfer, SPS flat bottom and acceleration ramp using end-to-end simulations. Starting from the measured bunch distributions, the simulations provide an accurate insight into the problem and allow direct benchmarking with experiments. As a result, it was understood and confirmed by measurements that shorter bunches do not necessarily lead to better transmission. The particle distribution in longitudinal phase space at PS extraction should be optimised instead. A significant loss reduction of up to 50 % is expected from simulations; experimental studies are on-going to verify these theoretical findings.  
slides icon Slides WEO1C03 [3.903 MB]  
 
WEO1C06 Measurement and Simulation of Luminosity Leveling in LHC via Beam Separation luminosity, simulation, beam-beam-effects, target 451
 
  • S. Paret, J. Qiang
    LBNL, Berkeley, California, USA
  • R. Alemany-Fernandez, R. Calaga, R. Giachino, W. Herr, D. Jacquet, G. Papotti, T. Pieloni, L. Ponce, M. Schaumann
    CERN, Geneva, Switzerland
  • R. Miyamoto
    ESS, Lund, Sweden
  
  Funding: This work supported by the US LHC Accelerator Research Program and the National Energy Research Scientific Computing Center of the U.S. Department of Energy under Contract No. DE-AC02-05CH11231.
Leveling of the luminosity in LHC by means of separating the beams colliding at an interaction point is examined. An experiment in which the separation of the beams was stepwise increased to up to 2.5 times the beam width is presented. The luminosity at all IPs and emittance of the beams were measured to detect possible side effects of the collision with an offset. Strong-strong simulations that closely follow the experimental setup are discussed and compared with the measurements. Finally, potential alternatives for luminosity leveling are briefly described. 		 
slides icon Slides WEO1C06 [1.031 MB]  
 
WEO3C03 Beam Halo Dynamics and Control with Hollow Electron Beams electron, collimation, collider, controls 466
 
  • G. Stancari, G. Annala, A. Didenko, T.R. Johnson, I.A. Morozov, V. Previtali, G.W. Saewert, V.D. Shiltsev, D.A. Still, A. Valishev, L.G. Vorobiev
    Fermilab, Batavia, USA
  • R.W. Aßmann, R. Bruce, S. Redaelli, A. Rossi, B. Salvachua, G. Valentino
    CERN, Geneva, Switzerland
  • D.N. Shatilov
    BINP SB RAS, Novosibirsk, Russia
  
  Funding: Fermilab is operated by Fermi Research Alliance, LLC under Contract DE-AC02-07CH11359 with the US Department of Energy. Partial support was provided by the US LHC Accelerator Research Program (LARP).
Experimental measurements of beam halo diffusion dynamics with collimator scans are reviewed. The concept of halo control with a hollow electron beam collimator, its demonstration at the Tevatron, and its possible applications at the LHC are discussed. 		 
slides icon Slides WEO3C03 [5.139 MB]  
 
THO1A01 Beam-beam Effects in RHIC proton, electron, resonance, simulation 479
 
  • Y. Luo, M. Bai, W. Fischer, C. Montag, S.M. White
    BNL, Upton, Long Island, New York, USA
  
  Funding: Work supported by Brookhaven Science Associates, LLC under Contract No. DE-AC02-98CH10886 with the U.S. Department of Energy.
In this article we will review the beam-beam effects in the Relativistic Heavy Ion Collider (RHIC). We will cover the experimental observations, beam-beam simulation techniques and results, and head-on beam-beam compensation with electron lenses. The next luminosity goal in the RHIC polarized proton operation is to double the luminosity with a higher proton bunch intensity. After the upgrade, the beam-beam parameter will reach 0.03. Head-on beam-beam compensation is aimed to reduce the beam-beam tune spread and non-linear beam-beam resonance driving terms. 		 
slides icon Slides THO1A01 [1.355 MB]  
 
THO3A02 Beam Dynamics of China ADS Linac linac, cavity, rfq, lattice 502
 
  • Z. Li
    Private Address, Beijing, People's Republic of China
  • P. Cheng, H. Geng, Z. Guo, C. Meng, B. Sun, J.Y. Tang, F. Yan
    IHEP, Beijing, People's Republic of China
  
  Funding: Supported by China ADS Program(XDA03020000), National Natural Science Fundation of China (10875099) and IHEP Special Fundings(Y0515550U1)
An ADS study program is approved by Chinese Academy of Sciences at 2011, which aims to design and built an ADS demonstration facility with the capability of more than 1000 MW thermal power within the following 25 years. The 15 MW driver accelerator will be designed and constructed by the Institute of High Energy Physics (IHEP) and Institute of Modern Physics (IMP) of China Academy of Sciences. This linac is characterized by the 1.5 GeV energy, 10 mA current and CW operation. It is composed by two parallel 10 MeV injectors and a main linac integrated with fault tolerance design. The superconducting acceleration structures are employed except the RFQ. The general considerations and the beam dynamics design of the driver accelerator will be presented. 		 
slides icon Slides THO3A02 [5.822 MB]  
 
THO3A03 Simulations and Measurements in High Intensity LEBT with Space Charge Compensation simulation, injection, space-charge, rfq 507
 
  • N. Chauvin
    CEA/IRFU, Gif-sur-Yvette, France
  • O. Delferrière, R. Gobin, P.A.P. Nghiem, D. Uriot
    CEA/DSM/IRFU, France
  • R.D. Duperrier
    ESS, Lund, Sweden
  
  Over the last years, the interest of the international scientific community for high power accelerators in the megawatt range has been increasing. One of the major challenges is to extract and transport the beam while minimizing the emittance growth in the Low Energy Beam Transport line (LEBT). Consequently, it is crucial to perform precise simulations and cautious design of LEBT. In particular, the beam dynamics calculations have to take into account not only the space charge effects but also the space charge compensation of the beam induced by ionization of the residual gas. The code SOLMAXP has been developed in CEA-Saclay to perform self-consistent calculations taking into account space charge compensation. Extensive beam dynamics simulations have been done with this code to design the IFMIF LEBT (Deuteron beam of 125 mA at 100 keV, cw). The commissioning of the IFMIF injector started a few months ago and emmittance measurements of H+ and D+ beams have been done. The first experimental results will be presented and compared to simulation.  
slides icon Slides THO3A03 [3.165 MB]  
 
THO3A04 Beam Halo Definitions and its Consequences linac, beam-losses, injection, space-charge 511
 
  • P.A.P. Nghiem, N. Chauvin, D. Uriot
    CEA/DSM/IRFU, France
  • W. Simeoni
    CEA/IRFU, Gif-sur-Yvette, France
  
  In high-intensity accelerators, much attention is paid to the beam halo: formation, growth interaction with the beam core, etc. Indeed, beam losses, a critical issue for those high-power accelerators, directly depend on the beam halo behaviour. But in the presence of very strong space-charge forces, the beam distribution takes very different shapes along the accelerator, often very far from any regular distributions, with very varied halo extensions. The difficulty is then to find a general definition of the halo capable of describing any distribution type. This paper proposes a definition of the beam halo, studies its consequences and compares it to the most usual ones.  
slides icon Slides THO3A04 [9.030 MB]  
 
THO1B04 Space Charge Effects in the NICA Collider Rings ion, collider, luminosity, electron 522
 
  • O.S. Kozlov, S.A. Kostromin, I.N. Meshkov, A.O. Sidorin, A.V. Smirnov, G.V. Trubnikov
    JINR, Dubna, Moscow Region, Russia
  • A.V. Eliseev
    JINR/VBLHEP, Dubna, Moscow region, Russia
  • T. Katayama
    GSI, Darmstadt, Germany
  
  Accelerator complex NICA, developed at JINR, will provide an ion-ion (Au79+) collisions at energies of 1-4.5 GeV/u, as well as experiments on collisions of polarized proton-proton and deuteron-deuteron beams. The calculations of the optical properties of superconducting collider rings have been aimed to create appropriate conditions for the collisions of beams and obtaining the required luminosity parameters in the working range of energies. The collider characteristics and the beam dynamics have been worked out mainly for ion-ion mode of the complex. The main effects limiting luminosity are the space charge dominating at the range of 1-3 GeV/u and the intrabeam scattering dominating for 3-4.5 GeV/u beams. Application of both electron and stochastic cooling methods is essential feature of the project. That allows us to suppress these effects in the corresponding energy ranges.  
slides icon Slides THO1B04 [3.938 MB]  
 
THO3B04 Beam Dynamics Studies of H− Beam Chopping in a LEBT for Project X ion, solenoid, simulation, ion-source 546
 
  • Q. Ji, D.P. Grote, A.R. Lambert, D. Li, T. Schenkel, J.W. Staples
    LBNL, Berkeley, California, USA
  
  Funding: This work is supported by the Office of Science, United States Department of Energy under DOE contract DE-AC02-05CH11231.
Project X is proposed as a high intensity proton facility at Fermilab to support a world-leading program in neutrino and flavor physics over the next several decades. The front-end consists of an H− ion source, low-energy beam transport (LEBT), and 162.5 MHz CW Radio-Frequency-Quadrupole (RFQ) accelerator. The LEBT design, currently under study at LBNL, would comprise two solenoids, a dipole magnet and a chopper. The LEBT chopper is designed to achieve 1 MHz beam chopping of a partially neutralized 30 keV, 5 mA H− beam. Preliminary simulation studies show that chopping the beam before the second solenoid is more efficient in terms of chopper bias voltages. However, the space charge neutralization will be lost along the beam after the chopper and through the second solenoid. A beam dynamics study, using WARP 3D (a Particle-in-cell simulation code), has been carried out to investigate both the time-dependence of the partial neutralization in the segment after the chopper, as well as the beam stability and emittance growth. Benchmark experiments are ongoing and simulation and experimental results will be presented in this Workshop. 		 
slides icon Slides THO3B04 [1.868 MB]  
 
THO1C04 Performances and Future Plans of the LHC RF cavity, klystron, injection, impedance 565
 
  • P. Baudrenghien, T. Mastoridis
    CERN, Geneva, Switzerland
  
  The ramp-up of the LHC operation has been exceptionally fast: from the first acceleration of a single bunch at nominal intensity (1.1· E11 p) to 3.5 TeV/c on May 2010, to the accumulation of 11 fb-1 integrated luminosity two years later (June 2012). On the RF side this was made possible by a few key design choices and several developments, that allow reliable LHC operation with 0.35 A DC beam at 4 TeV/c (1380 bunches at 50 ns spacing, 1.5·1011 p per bunch). This paper reviews the RF design and presents its performance. Plans are also outlined that would allow operation with 25 ns bunch spacing (doubling the beam current) and even increased bunch intensity with the target of above 1A DC current per beam, without big modification to the existing RF power system.  
slides icon Slides THO1C04 [9.945 MB]  
 
FRO1A02 WG-B: Beam Dynamics In High Intensity Linacs linac, rfq, DTL, resonance 612
 
  • D. Raparia
    BNL, Upton, Long Island, New York, USA
  • Z. Li
    IHEP, Beijing, People's Republic of China
  • P.A.P. Nghiem
    CEA/DSM/IRFU, France
  
  Emittance coupling, equipartioning and losses were a few topics, which were discussed thoroughly during parallel session for beam dynamics in high intensity linacs (Group B). Linac designs for the future, under construction, upgrade and the existing linacs from around the world were presented in three working sessions. A total of 18 talks were presented. Five presentations are general beam dynamics in nature and twelve talks were project specific. The detail of each contribution can be found in these proceedings. Here we report the summary of the discussions and some concluding remarks of the general interest to all the projects presented in the working group.  
slides icon Slides FRO1A02 [14.464 MB]