Crystal-Assisted Beam Extraction and Collimation at the U-70 Circular   Accelerator
  New crystal technique - array of bent strips and a fan-type reflector, based on thin straight plates - have been used for research of extraction and collimation a circulating beam in the U-70 accelerator at the energy 50 GeV and 1.3 GeV. It is shown, that new devices can effectively steer a beam in a wide energy range. For protons with energy 50 GeV efficiency of extraction and collimation about 90 % has been achieved which is record for this method. Reduction of particle losses in 2-3 times was observed also in accelerator at application of different crystals in comparison with the usual one-stage collimation scheme of beam with a steel absorber. 
A.G.Afonin, V.T.Baranov, S.Bellucci, S.A.Belov, S.Bini, V.N.Gorlov, G.   Giannini, A.D.Ermolaev, I.V.Ivanova, D.M.Krylov, V....
physics.acc-ph