Origin of the Anomalous Enhancement of 180° Backscattering Yields for Light Ions in Solid Targets

Abstract

The origin of the enhancement of the near-surface yield of backscattered projectiles at angles close to 180° for swift light ions in solid targets is shown to be a correlation between outgoing and incoming paths which occurs when an ion scatters by almost 180° in one of its collisions in a solid. The theory does not invoke the crystal structure, or the disturbance of the medium by the ion. Calculations agree with experiment for 1-MeV ${\mathrm{He}}^{++}$ in Pt.