Energy dependence of zero-degree focusing of channeled ions

We analyze here the energy dependence of the effect of zero-degree focusing of Ne10+ ions transmitted through the [100] channels of a Si crystal. The thickness of the crystal is 1 mu m and the ion energy is varied from 1.0 to 37 MeV per nucleon. The angular distributions of the transmitted ions were obtained by the computer simulation method using the numerical solution of the equations of motion of the ion, and two continuum interaction potentials of the ion and the crystal - Lindhards potential, and the corresponding catastrophic potential. We demonstrate that the effect of zero-degree focusing is periodic with the respect to variable E-1/2, where E is the ion energy, and that it decays with this variable. This periodicity is explained by the harmonic part of the continuum interaction potential, and the decay is attributed to the anharmonic part of the potential.3rd International Conference on Computer Simulation of Radiation Effects in Solids (COSIRES), Jul 22-26, 1996, Univ Surrey, Guildford, Englan