Study of reduction of multiple scattering of positively charged particles during channeling in (111) crystallographic silicon planes

The article proposes an analytical model to describe a recently discovered phenomenon of reduction of multiple scattering of positively charged particles during channeling in (111) crystallographic silicon planes. The phenomenon represents a strong suppression of the mean square angle of multiple scattering of such particles in a plane perpendicular to the channeling plane (in comparing with the non channeling particles). The proposed model is based on the development of our previously considered approximate description of the diffusion process in short crystals. Using successive reductions, we extended this description to fairly long crystals. Our analytical model explains the phenomenon observed in the experiments and allows us to calculate the behavior of the root mean-square angle of channeling particles as a function of the crystal thickness.