  Strong effect of beam coherent scattering ("reflection") in a field of bent
crystal is observed in crystal collimation experiments performed with heavy
ions and protons at RHIC and started at Tevatron collider. Detailed simulation
using Monte Carlo code CATCH is done in order to understand the observations
and relate them to the physics of beam coherent scattering in crystal. A.M.
Taratin and S.A. Vorobiev predicted the effect of beam "volume reflection" in
bent crystals in 1987. The presented data is the first manifestation of this
new physical phenomenon in experiment.
