Positron–Hydrogen Scattering at Intermediate Energies

Abstract

Calculations of positron–hydrogen scattering at intermediate energies up to a maximum energy of 10 Ryd are performed using the close coupling (CC) approach. A large L² basis of positron–hydrogen channels (28 states) is supplemented by the Ps(1s), Ps(2s) and Ps(2p) channels. The inclusion of the positronium states in the CC expansion leads to a model which can describe most of the physics of the positron–hydrogen system with a reasonable degree of accuracy. In particular, the positronium formation cross section, the total reaction cross section and the ionisation cross section are all in agreement with experiment. The elastic scattering cross section and the cross sections for positron impact excitation of the H(2s) and H(2p) levels are also reported.