03 Linear Colliders, Lepton Accelerators and New Acceleration Techniques

T19 Collimation and Targetry

Paper Title Page
WEPP157 Lithium Lens for Positron Production System 2856
 
  • A. A. Mikhailichenko
    Cornell University, Department of Physics, Ithaca, New York
  
  We represent optimized parameters for undulator-based positron production scheme for ILC-type machine. In particular we describe details of Lithium lens design suggested for usage in collection optics.  
WEPP158 Simulation of beam Halo in CLIC Collimation Systems 2859
 
  • G. A. Blair, S. Malton
    Royal Holloway, University of London, Surrey
  • I. V. Agapov, A. Latina, D. Schulte
    CERN, Geneva
  
  Full simulation of the CLIC and ILC collimation systems are performed to take account of collimator wakefield effects from the core beam on the halo. In addition full simulation of the interaction of the halo with the collimator material is performed to study the effect of multiple scattering and also the production of neutrons in the electromagnetic showers. The effect of beam-gas scattering downstream of the collimators is also included.  
WEPP161 Preliminary Experiments on a Fluidised Powder Target 2862
 
  • O. Caretta, C. J. Densham
    STFC/RAL, Chilton, Didcot, Oxon
  • T. W. Davies
    Exeter University, Exeter, Devon
  • R. M. Woods
    Gericke LTD, Ashton-under-Lyne
  
  In order to achieve higher resolutions the next generation of accelerator facilities is designed to operate with beam powers orders of magnitude higher than that handled by the current technology. So it is believed that the existing target and beam dump designs will be unsuitable to survive beam interactions depositing powers in the order of several megawatts. Good target design is important for the physics yield from experiments and crucial to the reliable operation of the facility. Furthermore the choice of target is strongly associated with the safety and cost of design (i.e., economic viability) of the entire facility. This article proposes a new target technology based on fluidised powder believed to be suitable for application at higher beam powers whilst avoiding some of the problems associated with other technologies. A conceptual system design for the application of the fluidised powder target to the requirements of a future neutrino facility, is presented. The preliminary experimental results presented, show the effect of some of the parameters which are expected to determine the performance, physics yields and reliability of operation of the new powder system.  
WEPP162 Beam Impact Studies on ILC Collimators 2865
 
  • G. Ellwood
    STFC/RAL, Chilton, Didcot, Oxon
  • J.-L. Fernandez-Hernando, J. K. Jones
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • M. Slater, N. K. Watson
    Birmingham University, Birmingham
  
  Spoilers in the ILC Beam Delivery System are required to survive without failure a minimum of 1-2 direct impacts of 250 GeV-500 GeV bunch of electrons or positrons, in addition to maintaining low geometric and resistive wall wake fields. Simulations were completed to determine the energy deposition of an ILC bunch to a set of different spoiler designs. These shower simulations were used as inputs to thermal and mechanical studies using ANSYS. This paper presents the results of testing carried out at the Accelerator Test Facility at KEK used to validate the simulations. Results from the first phase of testing, in which electron bunches of varying charge were incident on TI-6Al-4V foils, are presented and compared with simulations.  
WEPP163 Measurements of Collimator Wakefields at End Station A 2868
 
  • J.-L. Fernandez-Hernando
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • S. Molloy
    SLAC, Menlo Park, California
  • J. D.A. Smith
    Cockcroft Institute, Warrington, Cheshire
  • N. K. Watson
    Birmingham University, Birmingham
  
  The angular kicks imparted to an electron beam with energy of 28.5 GeV when it passes through a collimator jaw with a certain offset, generating a wakefield, were measured in End Station A (ESA) in SLAC for fifteen different collimator configurations of geometry and material. Some configurations were chosen in order to compare with previous measurements while others served to study the effect of geometry and taper angles (geometrical contribution to the wakefield) and the effect of the material resistivity (resistive contribution) to the kick. This paper summarises the final experimental results. The reconstructed kick factor is compared to analytical calculations and simulations.  
WEPP164 Beam Collimation Studies for the ILC Positron Source 2871
 
  • A. I. Drozhdin
    Fermilab, Batavia, Illinois
  • Y. Nosochkov, F. Zhou
    SLAC, Menlo Park, California
  
  The results of collimation studies for the ILC positron source beam line are presented. The calculations of primary positron beam loss are done using the ELEGANT code. The secondary positron and electron beam loss, synchrotron radiation along the beam line and bremsstrahlung radiation in the collimators are simulated using the STRUCT code. The first part of the system, located right after the positron source target at 0.125 GeV, is used for protection of super-conducting RF Linac from heating and radiation. The second part of the system is used for final collimation of the beam before injection to the Damping Ring at 5 GeV. The calculated power loss in the collimation region is about 100 W/m, with loss in the collimators of 0.2-5 kW. The beam transfer efficiency from target to the Damping Ring is 13.5%.  
WEPP165 GdfidL Simulations of International Linear Collider Candidate Collimator Assemblies 2874
 
  • J. D.A. Smith
    Cockcroft Institute, Warrington, Cheshire
  
  Collimator performance is critical to the successful operation of any collider. Building on previous GdfidL simulations of collimator jaws, this paper describes simulations where STL files of the complete assembly are investigated and wakefield performance is determined and optimised.  
WEPP166 Comparison of Collimator Wakefields Formulae 2877
 
  • A. M. Toader, R. J. Barlow
    UMAN, Manchester
  
  There is an extensive literature on transverse wakefield kick factors in collimators. We present a compendium of the formulae and discuss their agreement and disagreement with each other and with experimental results.  
WEPP167 Effect of Collimator Wakefields in the Beam Delivery System of the International Linear Collider 2880
 
  • A. M. Toader, R. J. Barlow
    UMAN, Manchester
  • D. Angal-Kalinin, F. Jackson
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  
  The collimators in the design of the International Linear Collider (ILC) Beam Delivery System (BDS) may be a significant source of wakefields and significantly degrade luminosity. New simulations are used to predict the effect of BDS collimator wakefields, and compared with previous analytical methods. BDS lattices optimised for improved collimation performance are also examined.  
WEPP168 Mechanical Design of Collimators for the ILC 2883
 
  • B. D. Fell, D. Angal-Kalinin, S. C. Appleton, J.-L. Fernandez-Hernando, F. Jackson, O. B. Malyshev
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • N. Bliss
    STFC/DL, Daresbury, Warrington, Cheshire
  • G. Ellwood, R. J.S. Greenhalgh
    STFC/RAL, Chilton, Didcot, Oxon
  • J. D.A. Smith
    Cockcroft Institute, Warrington, Cheshire
  • N. K. Watson
    Birmingham University, Birmingham
  
  Much attention has been paid to the optimisation of the geometry and material of collimators in the ILC to mitigate the effects of both short-range transverse wakefields and errant beam impacts. We discuss the competing demands imposed by realistic engineering constraints and present a preliminary engineering design for adjustable jaw spoilers for the ILC.  
WEPP169 The MERIT High-power Target Experiment at the CERN PS 2886
 
  • H. G. Kirk, H. Park, T. Tsang
    BNL, Upton, Long Island, New York
  • J. R.J. Bennett
    STFC/RAL/ISIS, Chilton, Didcot, Oxon
  • O. Caretta, P. Loveridge
    STFC/RAL, Chilton, Didcot, Oxon
  • A. J. Carroll, V. B. Graves, P. T. Spampinato
    ORNL, Oak Ridge, Tennessee
  • I. Efthymiopoulos, A. Fabich, F. Haug, J. Lettry, M. Palm, H. Pereira
    CERN, Geneva
  • K. T. McDonald
    PU, Princeton, New Jersey
  • N. V. Mokhov, S. I. Striganov
    Fermilab, Batavia, Illinois
  
  The MERIT experiment was designed as a proof-of-principle test of a target system based on a free mercury jet inside a 15-T solenoid that is capable of sustaining proton beam powers of up to 4MW. The experiment was run at CERN in the fall of 2007. We describe the results of the tests and their implications.