Total cross sections for positron scattering from H2 at low energies

Abstract

This paper revisits positron scattering from molecular hydrogen, in an attempt to provide accurate total cross-section data against which theoretical calculations might be benchmarked. The present data were measured over the energy range 0.1–50 eV and, where possible, are compared to results from previous experiments and calculations. Agreement with the earlier data was typically very good at energies above 10 eV but becomes progressively more marginal as we go to lower energies. None of the current theories quantitatively reproduce our measurements over the entire energy range, although at a qualitative level the main features driving the scattering dynamics are apparent.