Positronium formation in positron-hydrogen scattering

Calculations, using the Kohn variational method, have been made of the d-wave contributions to the elastic scattering and positronium formation cross sections for positron scattering by atomic hydrogen in the Ore gap, 6.8-10.2 eV. Very elaborate trial functions were used and it is believed that the results have converged to within 10% of their exact values. These results have been combined with others by the present authors for s- and p-wave scattering in an investigation of the behaviour of the total elastic scattering cross section in the vicinity of the positronium formation threshold and, also, of the angular distribution of the positronium. The findings of both investigations suggest a possible explanation of the discrepancy between the experimental measurements of the positronium formation cross section by Charlton et al. (1983) and Fornari et al. (1983).