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Nosochkov, Y.

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TUPMS051 Low Alpha Mode for SPEAR3 1308
  • X. Huang, W. J. Corbett, Y. Nosochkov, J. A. Safranek, J. J. Sebek, A. Terebilo
    SLAC, Menlo Park, California
  In the interest of obtaining shorter bunch length for shorter X-ray pulses, we have developed a low-alpha operational mode for SPEAR3. In this mode the momentum compaction factor is reduced by a factor of 21 or more from the usual achromat mode by introducing negative dispersion at the straight sections. We successfully stored 100~mA with the normal fill pattern at a lifetime of 30hrs. The bunch length was measured to be 6.9ps, compared to 17ps in the normal mode. In this paper we report our studies on the lattice design and calibration, orbit stability, higher order alpha measurement, lifetime measurement and its dependence on the sextupoles, injection efficiency and bunch lengths.  
TUPAS070 Optimization of Chromatic Optics Near the Half Integer in PEP-II 1814
  • G. Yocky, Y. Cai, F.-J. Decker, Y. Nosochkov, U. Wienands
    SLAC, Menlo Park, California
  • P. Raimondi
    INFN/LNF, Frascati (Roma)
  Measurements of the W-function in PEP-II during Run 5 revealed that the chromatic beta functions in both the HER and LER were not optimized. Through a process of measurement, offline analysis and modelling, and high-current run implementation the PEP-II collider luminosity performance was increased by at least 10% by reconfiguring the strengths of sextupoles near the IP to take advantage of a minimized W and increased IP bandwidth.  
WEOCAB01 Design of the Beam Delivery System for the International Linear Collider 1985
  • A. Seryi, J. A. Amann, R. Arnold, F. Asiri, K. L.F. Bane, P. Bellomo, E. Doyle, A. F. Fasso, L. Keller, J. Kim, K. Ko, Z. Li, T. W. Markiewicz, T. V.M. Maruyama, K. C. Moffeit, S. Molloy, Y. Nosochkov, N. Phinney, T. O. Raubenheimer, S. Seletskiy, S. Smith, C. M. Spencer, P. Tenenbaum, D. R. Walz, G. R. White, M. Woodley, M. Woods, L. Xiao
    SLAC, Menlo Park, California
  • I. V. Agapov, G. A. Blair, S. T. Boogert, J. Carter
    Royal Holloway, University of London, Surrey
  • M. Alabau, P. Bambade, J. Brossard, O. Dadoun
    LAL, Orsay
  • M. Anerella, A. K. Jain, A. Marone, B. Parker
    BNL, Upton, Long Island, New York
  • D. A.-K. Angal-Kalinin, C. D. Beard, J.-L. Fernandez-Hernando, P. Goudket, F. Jackson, J. K. Jones, A. Kalinin, P. A. McIntosh
    STFC/DL/ASTeC, Daresbury, Warrington, Cheshire
  • R. Appleby
    UMAN, Manchester
  • J. L. Baldy, D. Schulte
    CERN, Geneva
  • L. Bellantoni, A. I. Drozhdin, V. S. Kashikhin, V. Kuchler, T. Lackowski, N. V. Mokhov, N. Nakao, T. Peterson, M. C. Ross, S. I. Striganov, J. C. Tompkins, M. Wendt, X. Yang
    Fermilab, Batavia, Illinois
  • K. Buesser
    DESY, Hamburg
  • P. Burrows, G. B. Christian, C. I. Clarke, A. F. Hartin
    OXFORDphysics, Oxford, Oxon
  • G. Burt, A. C. Dexter
    Cockcroft Institute, Warrington, Cheshire
  • J. Carwardine, C. W. Saunders
    ANL, Argonne, Illinois
  • B. Constance, H. Dabiri Khah, C. Perry, C. Swinson
    JAI, Oxford
  • O. Delferriere, O. Napoly, J. Payet, D. Uriot
    CEA, Gif-sur-Yvette
  • C. J. Densham, R. J.S. Greenhalgh
    STFC/RAL, Chilton, Didcot, Oxon
  • A. Enomoto, S. Kuroda, T. Okugi, T. Sanami, Y. Suetsugu, T. Tauchi
    KEK, Ibaraki
  • A. Ferrari
    UU/ISV, Uppsala
  • J. Gronberg
    LLNL, Livermore, California
  • Y. Iwashita
    Kyoto ICR, Uji, Kyoto
  • W. Lohmann
    DESY Zeuthen, Zeuthen
  • L. Ma
    STFC/DL, Daresbury, Warrington, Cheshire
  • T. M. Mattison
    UBC, Vancouver, B. C.
  • T. S. Sanuki
    University of Tokyo, Tokyo
  • V. I. Telnov
    BINP SB RAS, Novosibirsk
  • E. T. Torrence
    University of Oregon, Eugene, Oregon
  • D. Warner
    Colorado University at Boulder, Boulder, Colorado
  • N. K. Watson
    Birmingham University, Birmingham
  • H. Y. Yamamoto
    Tohoku University, Sendai
  The beam delivery system for the linear collider focuses beams to nanometer sizes at the interaction point, collimates the beam halo to provide acceptable background in the detector and has a provision for state-of-the art beam instrumentation in order to reach the physics goals. The beam delivery system of the International Linear Collider has undergone several configuration changes recently. This paper describes the design details and status of the baseline configuration considered for the reference design.  
slides icon Slides  
THPMS060 Transport Optics Design and Multi-particle Tracking for the ILC Positron Source 3124
  • F. Zhou, Y. K. Batygin, Y. Nosochkov, J. Sheppard, M. Woodley
    SLAC, Menlo Park, California
  • W. Liu
    ANL, Argonne, Illinois
  Funding: U. S. DOE Contract DE-AC02-76SF00515

Undulator-based positron source is adopted as the International Linear Collider baseline design. Complete optics to transport the positron beam having large angular divergence and large energy spread from a thin Ti target to the entrance of the 5 GeV damping ring injection line is developed. Start-to-end multi-particle tracking through the beamline is performed including the optical matching device, capture accelerator system, transport system, superconducting booster linac, spin rotators, and energy compressor. Positron capture efficiency of different schemes (immersed vs shielded target, and flux concentrator vs quarter wave transformation for the optics matching system) is compared. For the scheme of a shielded target and quarter wave transformation, the simulation shows that 15.1% of the positrons from the target are captured within the damping ring 6-D acceptance at the entrance of the damping ring injection line.

THPMS091 The Superconducting Magnets of the ILC Beam Delivery System 3196
  • B. Parker, M. Anerella, J. Escallier, P. He, A. K. Jain, A. Marone
    BNL, Upton, Long Island, New York
  • Y. Nosochkov, A. Seryi
    SLAC, Menlo Park, California
  Funding: Work supported by the US Department of Energy under contract DE-AC02-98CH10886.

A wide variety of superconducting magnets are needed in the ILC Beam Delivery System (BDS) to maximize luminosity and minimize experimental backgrounds. Compact final focus quadrupoles and multifunction correction coils are used with 14 mr total crossing angle to focus incoming beams to few nanometer spot sizes while focusing outgoing disrupted beams into a separate extraction beam line. Large aperture anti-solenoids correct deleterious nonlinear effects that arise due to the overlap of focusing fields with the main detector solenoid. Far from the interaction point (IP) sets of strong small aperture octupoles help minimize backgrounds at the IP due to beam halo particles while weak large aperture dipoles integrated with the experimental detector reduce backgrounds due to beamstrahlung pairs generated at the IP. The physics requirements and magnetic design solutions for these magnets are reviewed in this paper.

THPAS057 Significant Lifetime and Background Improvements in PEP-II by Reducing the 3rd Order Chromaticity in LER with Orbit Bumps 3618
  • F.-J. Decker, Y. Nosochkov, M. K. Sullivan, G. Yocky
    SLAC, Menlo Park, California
  Funding: *Work supported by Department of Energy contract DE-AC03-76SF00515.

Orbit bumps in sextupoles are routinely used for tuning the luminosity in the PEP-II B-Factory. Anti-symmetric bumps in a sextupole pair generate dispersion, while symmetric bumps induce a tune shift and beta beat. By coming two of these symmetric bumps with opposite signs where the second pair is 90 degree away, the tune shift cancels and the beta beat doubles. In the low energy ring (LER) we have four sextupole pairs per arc, where pair 1 and 3 are at the same betatron phase and pair 2 and 4are 90 degree away. By making two symmetric bumps with opposite sign in pair 1 and 3 the tune shift and the beta beat outside this region cancel, BUT the LER lifetime improved by a factor of three, losses by a factor of five, and the beam-beam background in the drift chamber of the BaBar detector by 20%. Simulations showed that the phase change at the second sextupole pair introduced by the beta beat can completely cancel the third order chromaticity.

THPAS058 Lowering the Vertical Emittance in the LER Ring of PEP-II 3621
  • F.-J. Decker, Y. Cai, Y. Nosochkov, Y. T. Yan, G. Yocky
    SLAC, Menlo Park, California
  Funding: *Work supported by Department of Energy contract DE-AC03-76SF00515.

The low energy ring (LER) in PEP-II has a design emittance of 0.5 nm-rad in the vertical, compared to nearly 0.1 nm-rad for the HER ring. This was thought to come from the "vertical step" of about 1 m in the interaction straight, where the LER beam after horizontal separation gets bend vertical so it sits on top of the HER in the rest of the ring. Since the program MAD does not easily reveal the location of the major emittance contribution, a program was written to calculate the coupled "curly H" parameter of mode 2 (mainly vertical) along z. Weighting it with the magnet bending revealed that the weak long bends inside the "vertical step" did less than 20% of the emittance growth. More than 80% comes from the ends of the adjacent arcs with strong bends. This is caused by the coupling cancellation of the solenoid starting already there with the skew quadrupoles SK5 and 6. By introducing additional skews in the straight instead of SK5 and 6 the emittance could be reduced by a factor of ten in simulations, but with very strong skews. Reasonable strong magnets might generate a workable compromise, since a factor of two in emittance promises 50% more luminosity in beam-beam simulations.