Inelastic collisions of positrons with positive ions: A coupled-static treatment with an application to e +-Be + and e +-Mg + scattering

Abstract

The inelastic collisions of positrons with positive ions are treated for the first time within the framework of the coupled-static and frozen-core approximations. The method is used for calculating partial and total cross sections of the inelastic scattering of positrons by beryllium and magnesium positive ions with the assumption that only two channels (the elastic and rearrangement ones), are opened. The calculations are carried out, in each case, for eight values of the total angular momentum l(0⩽ l⩽7), at 29 values of the incident energy lying above the positronium formation thresholds (i.e. above 11.32 eV in e +-Be + scattering and above 7.923 eV in e +-Mg + scattering). In both cases the effect of “switching on” the polarisation potential of the positroniums on their coupled-static cross sections is investigated. Although the resulting positronium formation cross sections are smaller than the elastic ones, their large values should draw the attention of experimental and theoretical physicists to the field of positron-ion collisions.