• 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