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Alexahin, Y.

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TUOCKI03 Observations and Modeling of Beam-Beam Effects at the Tevatron Collider 725
  • A. Valishev, Y. Alexahin, V. A. Lebedev, R. S. Moore, V. D. Shiltsev
    Fermilab, Batavia, Illinois
  This report summarizes recent experience with beam-beam effects at the Tevatron collider. Improvements in the beam life time resulting from implementation of the new helical orbit are analyzed. Effects of second order chromaticity correction and beam-beam compensation with Electron Lenses are studied.  
slides icon Slides  
TUOCKI04 Experimental Demonstration of Beam-Beam Compensation by Tevatron Electron Lenses and Prospects for the LHC 728
  • V. D. Shiltsev, Y. Alexahin, V. Kamerdzhiev, G. F. Kuznetsov, X. Zhang
    Fermilab, Batavia, Illinois
  • K. Bishofberger
    LANL, Los Alamos, New Mexico
  We report the first experimental demonstration of compensation of beam-beam interaction effects with use of electron beams. Long-range and head-on interactions of high intensity proton and antiproton beams have been dominating sources of beam loss and lifetime limitations in the Tevatron in Collider Run II (2001-present). Electron lense acting on proton bunches has doubled their lifetime by compensating beam-beam interaction with antiprotons. We present results of the experiments, operational details and discuss possibilities of using electron lenses for beam-beam compensation in LHC.  
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TUPAS024 Experimental and Simulation Studies of Beam-Beam Compensation with Tevatron Electron Lenses 1703
  • V. Kamerdzhiev, Y. Alexahin, V. D. Shiltsev, A. Valishev, X. Zhang
    Fermilab, Batavia, Illinois
  • D. N. Shatilov
    BINP SB RAS, Novosibirsk
  Initially the Tevatron Electron Lenses (TELs) were intended for compensation of the beam-beam effect on the antiproton beam. Owing to recent increase in the number of antiprotons and reduction in their emittance, it is the proton beam now that suffers most from the beam-beam effect. We present results of beam studies, compare them with the results of computer simulations using LIFETRAC code and discuss possibilities of further improvements of the Beam-Beam Compensation efficiency in the Tevatron.  
THPMS090 A Complete Scheme of Ionization Cooling for a Muon Collider 3193
  • R. B. Palmer, J. S. Berg, R. C. Fernow, J. C. Gallardo, H. G. Kirk
    BNL, Upton, Long Island, New York
  • Y. Alexahin, D. V. Neuffer
    Fermilab, Batavia, Illinois
  • S. A. Kahn
    Muons, Inc, Batavia
  • D. J. Summers
    UMiss, University, Mississippi
  Funding: Work Supported by the United States Department of Energy, Contract No. DE-AC02-98CH10886.

We propose a complete scheme for cooling a muon beam for a muon collider. We first outline the parameters required for a multi-TeV muon collider. The cooling scheme starts with the front end of the Study 2a proposed Neutrino Factory. This yields bunch trains of both muon signs. Emittance exchange cooling in upward climbing helical lattices then reduces the longitudinal emittance until it becomes possible to combine the trains into single bunches, one of each sign. Further cooling is now possible in emittance exchange cooling rings. Final cooling to the required parameters is achieved in 50 T solenoids that use high temperature superconductor. Preliminary simulations of each element will be presented.

THPAN104 Coupled Optics Reconstruction from TBT Data using MAD-X 3471
  • Y. Alexahin, E. Gianfelice-Wendt
    Fermilab, Batavia, Illinois
  • V. V. Kapin
    MEPhI, Moscow
  • F. Schmidt
    CERN, Geneva
  Funding: Work supported by the Universities Research Assoc., Inc., under contract DE-AC02-76CH03000 with the U. S. Dept. of Energy

Turn-by-turn BPM data provide immediate information on the coupledoptics functions at BPM locations. In the case of small deviations from the known (design) uncoupled optics some cognizance of the sources of perturbation, BPM calibration errors and tilts can also be inferred without detailed lattice modelling. In practical situations, however, fitting the lattice model with the help of some optics code would lead to more reliable results. We present an algorithm for coupled optics reconstruction from TBT data on the basis of MAD-X and give examples of its application for the Fermilab Tevatron and Booster accelerators.

THPAN105 Effects of Space Charge and Magnet Nonlinearities on Beam Dynamics in the Fermilab Booster 3474
  • Y. Alexahin, A. I. Drozhdin, X. Yang
    Fermilab, Batavia, Illinois
  • N. Yu. Kazarinov
    JINR, Dubna, Moscow Region
  Funding: Work supported by the Universities Research Assoc., Inc., under contract DE-AC02-76CH03000 with the U. S. Dept. of Energy

Presently the Fermilab Booster can accomodate about half the maximum proton beam intensity which the Linac can deliver. One of the limitations is related to large vertical tuneshift produced by space-charge forces at injection energy. In the present report we study the nonlinear beam dynamics in the presence of space charge and magnet imperfections and analyze the possibility of space charge compensation with electron lenses.

THPAN106 6D Ionization Cooling Channel with Resonant Dispersion Generation 3477
  • Y. Alexahin, K. Yonehara
    Fermilab, Batavia, Illinois
  • R. B. Palmer
    BNL, Upton, Long Island, New York
  Funding: Work supported by the Universities Research Assoc., Inc., under contract DE-AC02-76CH03000 with the U. S. Dept. of Energy

For muons with preferable for ionization cooling momentum <300MeV/c the longitudinal motion is naturally undamped. In order to provide the longitudinal damping a correlation between muon momentum and transverse position - described in terms of the dispersion function - should be introduced. In the present report we consider the possibility of dispersion generation in a periodic sequence of alternating solenoids (FOFO channel) by choosing the tune in the second passband (i.e. above half-integer per cell) and tilting the solenoids in adjacent cells in the opposite direction. Analytical estimates as well as simulation results for equilibrium emittances and cooling rates are presented.

THPAN108 TBT Optics and Impedance Measurements at the Fermilab Main Injector 3480
  • E. Gianfelice-Wendt, Y. Alexahin
    Fermilab, Batavia, Illinois
  Funding: Work supported by the U. S. Department of Energy under Contract No. DE-AC02-76CH03000.

The Main Injector (MI) is a rapid cycling multipurpose accelerator. After completion of the Tevatron Run II, its primary application will be the acceleration of high intensity proton beams for neutrino experiments. To achieve the intensity goal a detailed knowledge of the optics and transverse impedances is necessary which can be obtained from Turn-By-Turn (TBT) beam position measurements. The recent MI Beam Position Monitor system upgrade made it possible to apply the TBT data analysis methods which were successfully used by the authors for the Tevatron. We present the results of MI optics measurements and the impedance estimates obtained from the betatron phase advance dependence on beam current.

FRPMS006 Optimization of the Helical Orbits in the Tevatron 3874
  • Y. Alexahin
    Fermilab, Batavia, Illinois
  Funding: Work supported by the Universities Research Assoc., Inc., under contract DE-AC02-76CH03000 with the U. S. Dept. of Energy

To avoid multiple head-on collisions the proton and antiproton beams in the Tevatron move along separate helical orbits created by 7 horizontal and 8 vertical electrostatic separators. Still the residual long-range beam-beam interactions can adversely affect particle motion at all stages from injection to collision. With increased intensity of the beams it became necessary to modify the orbits in order to mitigate the beam-beam effect on both antiprotons and protons. This report summarizes the work done on optimization of the Tevatron helical orbits, outlines the applied criteria and presents the achieved results.