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Scandale, W.

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TUODKI06 Observation of Proton Reflection on Bent Silicon Crystals at the CERN SPS 751
  • W. Scandale
    CERN, Geneva
  Funding: INTAS-CERN, contract number 05-96-7525 and CARE, contract number RII3-CT-2003-506395.

We report observations, performed by the H8-RD22 Collaboration*, of the so-called volume reflection effect with 400 GeV/c protons interacting with bent Silicon crystals in the H8 beam line at the CERN SPS. The volume reflection is closely related with particle channeling. This phenomenon occurs at the tangency point of a particle trajectory with the bent crystalline planes and consists in the reversal of the transverse component of the particle momentum. The measurements were collected with a high spatial resolution detector mainly based on Silicon strips. The proton beam was deviated in the direction opposite to that of channeling by ~12μrad, which is ~1.3 times the critical angle, with an efficiency larger than 97% in a range of the proton-to-crystal incident angle as large as the bending angle of crystallographic planes. This evidence opens new perspectives for manipulation of high-energy beams, e.g., for collimation and extraction in the new-generation of hadron colliders or as a method for high-energy experiments in the region near to the circulating beam.

* H8-RD22 collaboration: CERN, FNAL, INFN (Ferrara, Legnaro, Perugia, Roma, Milano, Trieste), IHEP, PNPI, JINR

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THPAN074 Space-Charge Compensation Options for the LHC Injector Complex 3390
  • F. Zimmermann, M. Aiba, M. Chanel, U. Dorda, R. Garoby, J.-P. Koutchouk, M. Martini, E. Metral, Y. Papaphilippou, W. Scandale
    CERN, Geneva
  • G. Franchetti
    GSI, Darmstadt
  • V. D. Shiltsev
    Fermilab, Batavia, Illinois
  Space-charge effects have been identified as the most serious intensity limitation in the CERN PS and PS booster, on the way towards ultimate LHC performance and beyond. We here explore the application of several previously proposed space-compensation methods to the two LHC pre-injector rings, for each scheme discussing its potential benefit, ease of implementation, beam-dynamics risk, and the R&D programme required. The methods considered include tune shift and resonance compensation via octupoles, nonlinear chromaticity, or electron lenses, and beam neutralization by an electron cloud, plasma or negative ions.  
FROAKI01 Magnet Acceptance and Allocation at the LHC Magnet Evaluation Board 3739
  • L. Bottura, P. Bestmann, N. Catalan-Lasheras, S. D. Fartoukh, S. S. Gilardoni, M. Giovannozzi, J. B. Jeanneret, M. Karppinen, A. M. Lombardi, K. H. Mess, D. P. Missiaen, M. Modena, R. Ostojic, Y. Papaphilippou, P. Pugnat, S. Ramberger, S. Sanfilippo, W. Scandale, F. Schmidt, N. Siegel, A. P. Siemko, D. Tommasini, T. Tortschanoff, E. Y. Wildner
    CERN, Geneva
  The normal- and superconducting magnets for the LHC ring have been carefully examined to insure that each of the more than 1800 assemblies is suitable for the operation in the accelerator. Magnet coordinators, hardware experts and accelerator physicists, joined in the LHC Magnet Evaluation Board, have contributed to this work that consists in the magnet acceptance, and the optimisation achieved by sorting magnets according to their geometry, field quality and quench level. This paper gives a description of the magnet approval mechanism that has been running since four years, reporting in a concise summary on the main results achieved. We take as specific indicators the computed mechanical aperture, the sorting efficiency with respect to systematic and random field errors in the magnets, and the case-by-case analysis necessary to accommodate hardware limitations such as quench limits and training.  
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