De-channeling in terms of instantaneous transition rates -- Computer simulations for 855 MeV electrons at (110) planes of diamond

TL;DR

This paper uses Monte Carlo simulations to analyze 855 MeV electron channeling in diamond (110) planes, focusing on transition rates and scattering processes, and improves the modeling of particle dynamics in the crystal.

Contribution

It introduces a detailed simulation approach incorporating scattering at bound electrons and derives improved drift and diffusion coefficients for the Fokker-Planck equation.

Findings

Channeling can be modeled by a single exponential after 15 μm.

Transition rates depend on penetration depth and reach equilibrium.

Enhanced drift and diffusion coefficients improve predictive modeling.

Abstract

Monte-Carlo simulation calculation have been performed for 855 MeV electrons channeling in (110) planes of a diamond single crystal. The continuum potential picture has been utilized. Both, the transverse potential and the angular distributions of the scattered electrons at screened atoms are based on the Doyle-Turner scattering factors which were extrapolated with the functional dependence of the Moli\`{e}re representation to large momentum transfers. Scattering cross-sections at bound electrons have been derived for energies less than 30 keV from the double differential cross-section as function of both, energy and momentum transfer, taking into account also longitudinal and transverse excitations. For energies above 30 keV the M{\o}ller cross-section is used. The dynamics of the particle in the continuum transverse potential has been described classically. Results of the channeling process are presented in terms of instantaneous transition rates as function of the penetration depth, indicating that channeling can be described by a single exponential function only after the equilibration phase has been reached after about 15 $\mu$m. As a byproduct, improved drift and diffusion coefficients entering the Fokker-Planck equation have been derived with which its predictive power can be improved.