Diffraction in heavy-particle channeling as a probe for correlated lattice vibrations

A quantum theory of heavy-particle channeling is used to make predictions of channeling effects for a realistic model of a vibrating crystal. The quantum theory requires the total wave function for a screened-Coulomb potential, which is developed using an eikonal method. The shapes of predicted back-scattering dips are shown to depend on two-body effects due to blocking of Fresnel diffraction peaks, and thus to depend sensitively on spatial correlations between the vibrating lattice atoms; corresponding classical calculations contain no analogous effect. Using a Debye model, calculations are compared with data on back-scattering of 300 keV protons in silicon, with limited success. Proposals are made for similar experiments, in which the effects of correlations should be considerably enhanced. (author)