Positronium collisions with rare-gas atoms

TL;DR

This paper calculates elastic and ionization scattering cross sections of positronium colliding with rare-gas atoms, especially xenon, using a pseudopotential and binary-encounter methods, and compares results with experimental data.

Contribution

It introduces a combined pseudopotential and binary-encounter approach for Ps-atom scattering, providing new insights into ionization cross sections and velocity-dependent cross section behavior.

Findings

Total scattering dominated by elastic and ionization processes

Ionization cross sections agree with previous impulse approximation calculations

Total cross section matches experimental data at higher velocities

Abstract

We calculate elastic scattering of positronium (Ps) by the Xe atom using the recently developed pseudopotential method [I. I. Fabrikant and G. F. Gribakin, Phys. Rev. A 90, 052717 (2014)] and review general features of Ps scattering from heavier rare-gas atoms: Ar, Kr, and Xe. The total scattering cross section is dominated by two contributions: elastic scattering and Ps ionization (breakup). To calculate the Ps ionization cross sections we use the binary-encounter method for Ps collisions with an atomic target. Our results for the ionization cross section agree well with previous calculations carried out in the impulse approximation. Our total Ps-Xe cross section, when plotted as a function of the projectile velocity, exhibits similarity with the electron-Xe cross section for the collision velocities higher than 0.8 a.u., and agrees very well with the measurements at Ps velocities above 0.5 a.u.