• W. Scandale, R. Losito
  CERN, Geneva
• A.M. Taratin
  JINR, Dubna, Moscow Region

The probability of inelastic nuclear interaction in crystals well aligned to the incoming beam is considerably smaller than for its amorphous orientation. Tests performed with 400 GeV/c protons of the CERN SPS and a short bent silicon crystal confirm this behavior: channeled protons interact with crystal nuclei at a rate more that 20 times smaller than protons with randomly oriented trajectories. On the other hand, the quasi parallel beam halo in a collider has a large probability of being channeled in a bent silicon crystals. Tests performed with 120 GeV stored protons in the SPS show that the inelastic nuclear losses decrease by more than five times when the silicon crystal is well oriented respect to the beam envelope. These observations suggest that bent silicon crystals used as a primary collimator in a hadron collider, such as the LHC, will produce a considerably reduced flux of nuclear losses respect to an amorphous material.