MCSAD: Monte Carlo simulations of atom displacements induced by fast electrons in solids

Abstract

Present contribution deals with Monte Carlo simulation of atom displacements rates resulting in solids based on a calculation algorithm supporting the description of the conditions favouring the occurrence of single fast electron elastic scattering in solids, leading to the displacement of atoms from their crystalline sites. Firstly, a McKinley-Feshbach differential cross-section renormalization is introduced by considering single elastic scattering events with scattering angles only within the interval [θ l , π], where θ l is the limiting angle, under which multiple scattering events with relative low scattering angles prevails over the single ones. On this basis, a Monte Carlo simulation code (MCSAD) of atom displacements induced by electrons and photons was implemented. In particular, total atom displacements produced along an electron travelling path were sampled in different solids matrix and compared with Oen-Holmes-Cahn theory predictions at different electron initial energies. As a result, it was concluded that Oen-Holmes-Cahn calculations overestimate normalized atom displacements rates in comparison with present MCSAD ones in a range up to between 10 to 73% rate, where maximum deviation were observed in YBCO for heaviest atom. It was also found that Oen-Holmes-Cahn absolute atom displacements distributions overestimated in about 30 to 40 times at the maximum of the AD rate simulated by MCSAD code.