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Hartin, A.F.

Paper Title Page
MOPLS122 Design of the ILC Prototype FONT4 Digital Intra-train Beam-based Feedback System 849
 
  • P. Burrows
    Queen Mary University of London, London
  • G.B. Christian, H. Dabiri Khah, A.F. Hartin, G.R. White
    JAI, Oxford
  • C.C. Clarke, C. Perry
    OXFORDphysics, Oxford, Oxon
  • A. Kalinin
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • D.J. McCormick, S. Molloy, M.C. Ross
    SLAC, Menlo Park, California
 
  We report on the design and initial testing of the 4th generation Feedback on Nanosecond Timescales (FONT) prototype intra-train beam-based feedback system for beam control and luminosity optimisation at the International Linear Collider (ILC). FONT4 comprises a fast-analogue front-end BPM signal processor, with an FPGA-based digital feedback processor and a fast-risetime kicker-driver amplifier. The system is being designed with a total latency budget (including signal propagation delays) of about 140ns. FONT4 will be deployed at the Accelerator Test Facility (ATF) at KEK, where it will be tested with the electron bunchtrain extracted from the ATF damping ring. The bunches will have a spacing of c. 150ns, chosen to match the ILC design. We report the results of initial beam tests of the system components. We aim to demonstrate feedback, with delay-loop operation, on this ILC-like bunchtrain.  
MOPLS123 Performance of the FONT3 Fast Analogue Intra-train Beam-based Feedback System at ATF 852
 
  • P. Burrows
    Queen Mary University of London, London
  • G.B. Christian, A.F. Hartin, H.D. Khah, G.R. White
    JAI, Oxford
  • C.C. Clarke, C. Perry
    OXFORDphysics, Oxford, Oxon
  • A. Kalinin
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • D.J. McCormick, S. Molloy, M.C. Ross
    SLAC, Menlo Park, California
 
  We report on the design and testing of the 3rd generation Feedback On Nanosecond Timescales (FONT) prototype intra-train beam-based feedback system for beam control and luminosity optimisation at the International Linear Collider (ILC). The all-analogue FONT3 electronics was designed to have an ultra-short latency of c. 10ns. We describe the design of the BPM signal processor, feedback circuit and kicker-driver amplifier. We report on deployment of FONT3 at the Accelerator Test Facility (ATF) at KEK, where it was tested with the 56ns-long electron bunchtrain extracted from the ATF damping ring. Feedback, with delay-loop operation, on the beam was demonstrated with a latency close to design. We comment on the applicability of this technology to ILC, as well as future warm-RF based linear colliders, such as CLIC.  
MOPLS076 The Stimulated Breit-Wheeler Process as a Source of Background e+e- Pairs at the ILC 727
 
  • A.F. Hartin, A.F. Hartin
    OXFORDphysics, Oxford, Oxon
 
  Passage of beamstrahlung photons through the bunch fields at the interaction point of the ILC determines background pair production. The number of background pairs per bunch crossing due to the Breit-Wheeler, Bethe-Heitler and Landau-Lifshitz processes is well known. However the Breit-Wheeler process also takes place in and is modified by the bunch fields. A full QED calculation of this Stimulated Breit-Wheeler process reveals cross section resonances due to the virtual particle reaching the mass shell. The one loop Electron Self energy in the bunch field is also calculated and included as a radiative correction. The bunch field is considered to be a contant crossed electromagnetic field with associated bunch field photons. Resonance is found to occur whenever the energy of contributed bunch field photons is equal to the beamstrahlung photon energy. The Stimulated Breit-Wheeler cross section exceeds the ordinary Breit-Wheeler cross section by several orders of magnitude and a significantly different pair background may result.  
MOPLS076 The Stimulated Breit-Wheeler Process as a Source of Background e+e- Pairs at the ILC 727
 
  • A.F. Hartin, A.F. Hartin
    OXFORDphysics, Oxford, Oxon
 
  Passage of beamstrahlung photons through the bunch fields at the interaction point of the ILC determines background pair production. The number of background pairs per bunch crossing due to the Breit-Wheeler, Bethe-Heitler and Landau-Lifshitz processes is well known. However the Breit-Wheeler process also takes place in and is modified by the bunch fields. A full QED calculation of this Stimulated Breit-Wheeler process reveals cross section resonances due to the virtual particle reaching the mass shell. The one loop Electron Self energy in the bunch field is also calculated and included as a radiative correction. The bunch field is considered to be a contant crossed electromagnetic field with associated bunch field photons. Resonance is found to occur whenever the energy of contributed bunch field photons is equal to the beamstrahlung photon energy. The Stimulated Breit-Wheeler cross section exceeds the ordinary Breit-Wheeler cross section by several orders of magnitude and a significantly different pair background may result.  
THPCH089 The Electromagnetic Background Environment for the Interaction-point Beam Feedback System at the International Linear Collider 2997
 
  • G.B. Christian, P. Burrows, G.B. Christian, C.C. Clarke, A.F. Hartin, C. Swinson, G.R. White
    OXFORDphysics, Oxford, Oxon
  • R. Arnold, C. Hast, S. Smith, M. Woods
    SLAC, Menlo Park, California
  • A. Kalinin
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
 
  The Interaction Point (IP) feedback system is essential for maintaining the luminosity at the International Linear Collider (ILC). It is necessary to demonstrate the performance of the feedback beam position monitor (BPM) in an electron-positron pair background similar to that expected in the ILC interaction region (IR). We have simulated the ILC beam-beam interactions and used a GEANT model of the IR to evaluate the pair and photon flux incident on the BPM, for both the 2 mrad and 20 mrad crossing angle geometries. We present results as a function of the proposed machine parameter schemes, as well as for various system layouts within the IR. We plan to study the degradation of BPM resolution, and the long term survivability, in beam tests at End Station A at SLAC. To simulate the background environment of the ILC a 'spray beam' will be produced, which will scatter from a mechanical mock-up of the forward region of the IR, and irradiate the BPM with realistic flux of secondary pairs. We present the proposed experimental layout and planned beam tests.  
MOPLS067 Test Beam Studies at SLAC's End Station A, for the International Linear Collider 700
 
  • M. Woods, C. Adolphsen, R. Arnold, G.B. Bowden, G.R. Bower, R.A. Erickson, H. Fieguth, J.C. Frisch, C. Hast, R.H. Iverson, Z. Li, T.W. Markiewicz, D.J. McCormick, S. Molloy, J. Nelson, M.T.F. Pivi, M.C. Ross, S. Seletskiy, A. Seryi, S. Smith, Z. Szalata, P. Tenenbaum
    SLAC, Menlo Park, California
  • D. Adey, M.C. Stockton, N.K. Watson
    Birmingham University, Birmingham
  • M. Albrecht, M.H. Hildreth
    Notre Dame University, Notre Dame, Iowa
  • W.W.M. Allison, V. Blackmore, P. Burrows, G.B. Christian, C.C. Clarke, G. Doucas, A.F. Hartin, B. Ottewell, C. Perry, C. Swinson, G.R. White
    OXFORDphysics, Oxford, Oxon
  • D.A.-K. Angal-Kalinin, C.D. Beard, J.L. Fernandez-Hernando, F. Jackson, A. Kalinin
    CCLRC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • R.J. Barlow, A. Bungau, G.Yu. Kourevlev, A. Mercer
    UMAN, Manchester
  • S.T. Boogert
    Royal Holloway, University of London, Surrey
  • D.A. Burton, J.D.A. Smith, R. Tucker
    Lancaster University, Lancaster
  • W.E. Chickering, C.T. Hlaing, O.N. Khainovski, Y.K. Kolomensky, T. Orimoto
    UCB, Berkeley, California
  • C. Densham, R.J.S. Greenhalgh
    CCLRC/DL, Daresbury, Warrington, Cheshire
  • V. Duginov, S.A. Kostromin, N.A. Morozov
    JINR, Dubna, Moscow Region
  • G. Ellwood, P.G. Huggard, J. O'Dell
    CCLRC/RAL, Chilton, Didcot, Oxon
  • F. Gournaris, A. Lyapin, B. Maiheu, S. Malton, D.J. Miller, M.W. Wing
    UCL, London
  • M.B. Johnston
    University of Oxford, Clarendon Laboratory, Oxford
  • M.F. Kimmitt
    University of Essex, Physics Centre, Colchester
  • H.J. Schriber, M. Viti
    DESY Zeuthen, Zeuthen
  • N. Shales, A. Sopczak
    Microwave Research Group, Lancaster University, Lancaster
  • N. Sinev, E.T. Torrence
    University of Oregon, Eugene, Oregon
  • M. Slater, M.T. Thomson, D.R. Ward
    University of Cambridge, Cambridge
  • Y. Sugimoto
    KEK, Ibaraki
  • S. Walston
    LLNL, Livermore, California
  • T. Weiland
    TEMF, Darmstadt
  • M. Wendt
    Fermilab, Batavia, Illinois
  • I. Zagorodnov
    DESY, Hamburg
  • F. Zimmermann
    CERN, Geneva
 
  The SLAC Linac can deliver to End Station A a high-energy test beam with similar beam parameters as for the International Linear Collider for bunch charge, bunch length and bunch energy spread. ESA beam tests run parasitically with PEP-II with single damped bunches at 10Hz, beam energy of 28.5 GeV and bunch charge of (1.5-2.0)·1010 electrons. A 5-day commissioning run was performed in January 2006, followed by a 2-week run in April. We describe the beamline configuration and beam setup for these runs, and give an overview of the tests being carried out. These tests include studies of collimator wakefields, prototype energy spectrometers, prototype beam position monitors for the ILC Linac, and characterization of beam-induced electro-magnetic interference along the ESA beamline.