  The studies of crystal collimation in the experiments at Relativistic Heavy
Ion Collider and Tevatron and in computer simulations reveal strong coherent
effects observed in a very broad angular range. Our theory explains the effects
by coherent scattering on the potential of bent crystal atomic planes, which
amplifies beam diffusion in accelerator by orders of magnitude. This coherent
scattering in bent crystal is being studied in a CERN SPS experiment. We
present Monte Carlo predictions for the SPS and Tevatron experiments, and show
the implications of the coherent scattering effect for crystal collimation in
the Large Hadron Collider.
