Grazing scattering of 1-2Â MeV HeH+ ions from KCl(0Â 0Â 1): Effect of surface track potential

Three dimensional (3D) distributions (energy E, scattering angle θ and azimuth angle φ) of the fragment protons dissociated from HeH+ during grazing angle scattering from a KCl(0 0 1) are measured using a magnetic spectrometer in order to study the effect of the surface track potential. The distributions of the fragment protons scattered from a SnTe(0 0 1) are also measured as a reference. Although the observed distributions for KCl(0 0 1) and SnTe(0 0 1) are basically the same, there is small differences, especially in the scattering angle distribution. While the fragment protons are scattered at the specular angle from SnTe(0 0 1), the protons are scattered at slightly larger angles from KCl(0 0 1). The observed angular shift is more pronounced for the trailing protons than the leading protons. It is also found that the angular shift increases with decreasing ion energy. The observed angular shift can be qualitatively explained by the surface track potential induced by the partner He ions using a simple model of the surface track potential.