Transition of axial to planar channeling

Abstract

The transition from axial to planar channeling involves an angular region, where dechanneling is maximum. It is caused by the intermediate strong effect of the discrete atomic structure of lattice planes on the guidance of charged swift projectiles. The width of the transition region depends on the initial axial direction and the chosen tilt plane. Experimental evidence is presented in the change of the energy loss spectra of 100-MeV sulfur ions transmitted through 24-μm silicon along (110) with tilt in {112}. Computer simulations are performed with 40-MeV sulfur ions through 4.8-μm silicon along (110) with tilt in {112}. An universal analytical relation is derived to calculate the minimum tilt angle required for planar channeling to be effective. The relation is checked by comparison with a wide variety of experimental results. Finally, the experimental dechanneling length of 100-MeV sulfur ions transmitted through silicon along {112} planes is found to be about 13 μm, in agreement with estimates from the diffusion model of dechanneling.