Cross sections for elastic scattering of fast electrons and positrons by atoms

Abstract

In order to provide reliable cross section data needed for Monte Carlo simulation of high-energy electron and positron transport, a simple procedure to evaluate cross sections for elastic scattering of these particles by neutral atoms is described. Our approach starts from the exact Mott cross section for scattering by a bare point nucleus. Screening effects are accounted for by means of the Born approximation. A correction, for which we give a simple analytical expression, is introduced to compensate for the inaccuracies of the Born approximation at low energies. This correction has been determined from an extensive partial wave calculation involving 20 elements within the periodic system and electrons and positrons with kinetic energies from 1 keV to 10 MeV. Finite nuclear size effects are introduced by means of the Born approximation and a simple nuclear charge distribution. The resulting differential cross sections are adequate for describing multiple elastic scattering of electrons and positrons with kinetic energies above ∼ZkeV, where Z is the atomic number of the target atom.