Performance Evaluation of a Crystal-Enhanced Collimation System for the LHC

The Large Hadron Collider (LHC) has been constructed at CERN (Conseil Europeen pour la Recherche Nucleaire, Geneva, Switzerland), and recently started up. The LHC beams, currently accelerated to 3.5 TeV, are meant to reach the nominal energy of 7 TeV, and a total stored energy, in nominal conditions, of 360 MJ per beam [1, 2]. The contrast between the huge stored power and the delicate cryogenic environment calls for a sophisticated collimation system [3]. For overcoming the limitations of the actual collimation system, different upgrade solutions have been considered [4, 5, 6]; this Ph.D. work gives a first performance evaluation of a crystal-enhanced collimation system by analytical, experimental and simulation investigations. In this work, two crystal collimation experiments are described: the T980 (Tevatron, Chicago, U.S.) and the UA9 (SPS, CERN, Geneva, Switzerland). The data are analyzed and actual crystal performances are measured. These experimental results and their cross-check with dedicated simulations constitute the foundations of a weighted, critical prediction for the LHC. Different scenarios for a possible LHC crystal-enhanced collimation system have been simulated. Here the results are described and optimal parameters for a possible crystal collimator are proposed.

[1]  Frank Zimmermann,et al.  Electron cloud simulations: beam instabilities and wakefields , 2002 .

[2]  A R Plummer,et al.  Introduction to Solid State Physics , 1967 .

[3]  Y. Chesnokov,et al.  Crystal Channeling and Its Application at High-Energy Accelerators , 1997 .

[4]  A. Ferrari,et al.  FLUKA: A Multi-Particle Transport Code , 2005 .

[5]  J. Jeanneret.  Optics of a two-stage collimation system , 1998 .

[6]  G. Robert-Demolaize,et al.  Design and Performance Optimization of the LHC Collimation System , 2006 .

[7]  C. Bracco.  Commissioning scenarios and tests for the LHC collimation system , 2009 .

[8]  S. Redaelli,et al.  LHC APERTURE AND COMMISSIONING OF THE COLLIMATION SYSTEM , 2005 .

[9]  V. Golovatyuk,et al.  F Fermi National Accelerator Laboratory FERMILAB-Pub-99 / 186-E Beam Extraction Studies at 900 GeV Using a Channeling Crystal , 1999 .

[10]  A. Valishev,et al.  PROSPECTS FOR INTEGRATING A HOLLOW ELECTRON LENS INTO THE LHC COLLIMATION SYSTEM , 2009 .

[11]  G. Martinelli,et al.  Tailoring of silicon crystals for relativistic-particle channeling , 2005 .

[12]  F. Schmidt,et al.  Tools for predicting cleaning efficiency in the LHC , 2003, Proceedings of the 2003 Particle Accelerator Conference.

[13]  S. Fartoukh,et al.  LHC ABORT GAP FILLING BY PROTON BEAM , 2004 .

[14]  K. Elsener,et al.  On the energy dependence of proton beam extraction with a bent crystal , 1998 .

[15]  V. Shiltsev,et al.  FAST PIN-DIODE BEAM LOSS MONITORS AT TEVATRON , 1997 .

[16]  N. S. Barnett,et al.  Private communication , 1969 .

[17]  F. Cerutti,et al.  The FLUKA code: Description and benchmarking , 2007 .

[18]  V. Scarpine,et al.  Tevatron Electron Lenses: Design and Operation , 2008, 0808.1542.

[19]  M. Jonker,et al.  Beam loss response measurements with a LHC prototype collimator in the SPS , 2007, 2007 IEEE Particle Accelerator Conference (PAC).

[20]  R. Fliller.  The Crystal Collimation System of the Relativistic Heavy Ion Collider , 2004 .

[21]  K. Wille.  The Physics of Particle Accelerators: An Introduction , 2001 .

[22]  C. Luci,et al.  Volume reflection dependence of 400 GeV/c protons on the bent crystal curvature. , 2008, Physical review letters.

[23]  R. Guinand,et al.  First results on proton extraction from the CERN SPS with a bent crystal , 1993 .

[24]  What did we learn from the extraction experiments with bent crystals at the CERN SPS , 1998 .

[25]  J. Jeanneret,et al.  The Principles of Two Stage Betatron and Momentum Collimation in Circular Accelerators , 1995 .

[26]  Donald S. Gemmell,et al.  Channeling and related effects in the motion of charged particles through crystals , 1974 .

[27]  Maslov,et al.  The SSC beam scraper system , 1991 .

[28]  K. Goulianos.  Diffractive interactions of hadrons at high energies , 1983 .

[29]  Raymond P. Fliller,et al.  Channeling collimation studies at the Fermilab Tevatron , 2006, International Conference on Charged and Neutral Particles Channeling Phenomena.

[30]  C. Luci,et al.  Observation of multiple volume reflection of ultrarelativistic protons by a sequence of several bent silicon crystals. , 2009, Physical review letters.

[31]  C. Luci,et al.  High-efficiency deflection of high-energy protons through axial channeling in a bent crystal. , 2008, Physical review letters.

[32]  B. Goddard,et al.  Requirements for the LHC collimation system , 2002 .

[33]  R Losito,et al.  The UA9 Experiment at the CERN-SPS , 2009 .

[34]  S. Redaelli,et al.  Optics study for a possible crystal-based collimation system for the LHC , 2006 .

[35]  D. Leroy,et al.  Quench levels and transient beam losses in LHC magnets , 1996 .

[36]  Paolo Valente,et al.  High-efficiency volume reflection of an ultrarelativistic proton beam with a bent silicon crystal. , 2007, Physical review letters.

[37]  M. Oriunno,et al.  First results on the SPS beam collimation with bent crystals , 2010 .

[38]  V. Golovatyuk,et al.  First observation of luminosity-driven extraction using channeling with a bent crystal , 1998 .

[39]  G. Martinelli,et al.  Apparatus to study crystal channeling and volume reflection phenomena at the SPS H8 beamline. , 2008, The Review of scientific instruments.

[40]  Gert Moliere,et al.  Theorie der Streuung schneller geladener Teilchen I. Einzelstreuung am abgeschirmten Coulomb-Feld , 1947 .

[41]  B. Szeless,et al.  Thermal modelling of the LHC dipoles functioning in superfluid helium , 1994 .

[42]  A. Petrunin,et al.  Observation of the elastic quasi-mosaicity effect in bent silicon single crystals , 2005 .

[43]  W. Scandale.  CRYSTAL-BASED COLLIMATION IN MODERN HADRON COLLIDERS , 2010 .

[44]  S. Redaelli,et al.  A New Version of Sixtrack with Collimation and Aperture Interface , 2005, Proceedings of the 2005 Particle Accelerator Conference.

[45]  Ralph Wolfgang Assmann,et al.  Accelerator physics concept for upgraded LHC collimation performance , 2009 .

[46]  G. V. Chester,et al.  Solid State Physics , 2000 .