Backscattering study and theoretical investigation of planar-channeling processes. II. The unperturbed-oscillator model

Abstract

Particle trajectories in planar channeling are investigated theoretically in the continuum potential approximation neglecting all statistical effects. The choice of the planar potential used is discussed. The flux distributions in the planar channels are calculated in detail; they appear to exhibit, at distances $y$ of the channel center, strong maxima which vary in number, position, and intensity with penetration depths $x$. The flux near the channel center oscillates strongly with depth. The backscattering yields as a function of depth are calculated for beams entering the crystal with various incident angles ${\ensuremath{\phi}}_{0}$ with respect to the planes. The effect of beam angular divergence is taken into account and discussed. The oscillating calculated backscattering yields are in good qualitative and, in some cases, semiquantitative agreement with the experimental results obtained in a preceding paper. Angular scans were plotted for various depth intervals; they also compare favorably with the experimental results. However, some quantitative discrepancies observed between the calculations and the experimental results set a limit to the validity of the unperturbed oscillator model and illustrate the roles of the thermal effects and of the competition between correlated and uncorrelated scattering events.