Progess of Crystal Channeling Technique for Beam Extraction and Collimation at IHEP

We report progress achieved in crystal-assisted slow extraction and collimation of the 70-GeV proton beam in the U-70 accelerator at IHEP-Protvino. We recently obtained an extraction efficiency of 85.3±2.8% for a beam of ∼1012 proton directed towards very short crystals of ∼2 mm length in spills of ∼2 s duration. The experimental data follow very well the theoretical predictions obtained with Monte Carlo simulations. This success is important to devise a more efficient use of the U-70 accelerator in Protvino and suggests a possible way of implementingcrystal-assisted slow extraction and collimation in other machines, such as the Tevatron, RHIC, the AGS, the SNS, COSY, and the LHC.