The effect of forward-angle scattering on positronium-gas total cross sections

Abstract

An investigation into forward-angle scattering of Ps atoms from atomic and molecular targets is reported. This effect has been evaluated by varying the angular acceptance of the detector. theta, in the range +/-1.5 degrees to +/-6.4 degrees. By assuming an average differential cross section over this range, values of the total cross section (extrapolated to theta --> 0) for Ps-He, Ar and H-2 have been obtained. Where possible, the data are compared with available theoretical calculations.