Extraction of the Proton Beam from the 70 GeV IHEP Accelerator
  This paper presents the physical background for particle extraction from IHEP accelerator using short bent silicon crystals, analyses the results of the studies, considers in detail the regime of simultaneous work of crystal extraction and several internal targets. It is experimentally shown that the use of short crystals allows the extraction of beams with intensity of 10e12 proton/cycle with efficiency of 85%. 
A.G. Afonin, V.T. Baranov, V.M. Biryukov, I.M. Ivanov, A.A. Kardash,   V.I. Kotov, V.A. Maisheev, V.I.Terekhov, E.F. Troyano...