• V.D. Shiltsev, G. Annala, R.A. Carrigan, A.I. Drozhdin, T.R. Johnson, A.M. Legan, N.V. Mokhov, R.E. Reilly, D.A. Still, R. Tesarek, J.R. Zagel
  Fermilab, Batavia
• R.W. Assmann, V.P. Previtali, W. Scandale
  CERN, Geneva
• Y.A. Chesnokov, I.A. Yazynin
  IHEP Protvino, Protvino, Moscow Region
• V. Guidi
  INFN-Ferrara, Ferrara
• Yu.M. Ivanov
  PNPI, Gatchina, Leningrad District
• S. Peggs
  BNL, Upton, Long Island, New York

The T980 crystal collimation experiment is underway at the Tevatron to study various crystal types and parameters and evaluate if this technique would increase TeV beam-halo collimation efficiency at high-energy hadron colliders such as the Tevatron and the LHC. The setup has been substantially enhanced during the Summer 2009 shutdown by installing a new O-shaped crystal in the horizontal goniometer, adding a vertical goniometer with two alternating crystals (O-shaped and multi-strip) and additional beam diagnostics. First measurements with the new system are quite encouraging, with channeled and volume-reflected beams observed on the secondary collimators as predicted. Investigation of crystal collimation efficiencies with crystals in volume reflection and channeling modes are described in comparison with an amorphous primary collimator. Results on the system performance are presented for the end-of-store studies and for entire collider stores. Planning is underway for dedicated studies during a Tevatron post-collider physics running period.

Slides

• V. Guidi, E. Bagli, A. Mazzolari
  INFN-Ferrara, Ferrara
• A.G. Afonin, Y.A. Chesnokov, V.A. Maisheev, I.A. Yazynin
  IHEP Protvino, Protvino, Moscow Region
• S. Baricordi, P. Dalpiaz, M. Fiorini, D. Vincenzi
  UNIFE, Ferrara
• D. Bolognini, S. Hasan, M. Prest
  Università dell'Insubria & INFN Milano Bicocca, Como
• G. Della Mea, R. Milan
  INFN/LNL, Legnaro (PD)
• A.S. Denisov, Yu.A. Gavrikov, Yu.M. Ivanov, L.P. Lapina, L.G. Malyarenko, V. Skorobogatov, V.M. Suvorov, S.A. Vavilov
  PNPI, Gatchina, Leningrad District
• S. Golovatyuk, A.D. Kovalenko, A.M. Taratin
  JINR, Dubna, Moscow Region
• A. Mattera
  INFN MIB, MILANO
• W. Scandale
  CERN, Geneva
• S. Shiraishi
  Enrico Fermi Institute, University of Chicago, Chicago, Illinois
• E. Vallazza
  INFN-Trieste, Trieste
• A. V. Vomiero
  INFM-CNR, Istituto Nazionale di Fisica della Materia - Consiglio Nazionale delle Ricerche, Brescia

New results in coherent interaction of negatively-charged particles with bent crystals showed unprecedentedly and significantly high efficiency to manipulate such beams, in the same way as for positively charged particles. Key feature under experimental attainment was the usage of high-quality suitably thin silicon crystals. We experimentally tested crystals Vs. 150 GeV negative pions at external lines of CERN SPS. We observed planar channeling at full deflection angle 30% high single-pass efficiency and large acceptance (about 20μrad). Moreover in the axial case, we reached more than 90% deflection efficiency and larger acceptance (about 60μrad). We also observed volume reflection in a bent crystal, at more than 70% single-pass efficiency with such a wide acceptance as the bending angle. At last, volume reflection by several planes in a single bent crystal was successfully tested with very high efficiency (about 80%). In summary both channeling and volume reflection modes appear to be useful technique for the manipulation of negatively charged beams, e.g. for collimation in the new generation of high intensity accelerators.

The UA9 collaboration