  It is shown that a narrow plane cut near the crystal surface considerably
increases the probability of capture into the stable channeling motion of
positively charged particles entering a crystal at angles smaller than a
quarter of the critical channeling angle with respect to the crystal planes. At
smallest incidence angles the capture probability reaches 99 percent. A pair of
crystals with cuts bent in orthogonal planes allows to reach a 99.9 percent
efficiency of single-pass deflection of a proton beam with an ultra small
divergence. Conditions necessary for efficient single-pass deflection of
protons from the LHC beam halo are discussed.
