Total scattering cross sections for intermediate-energy positrons in the molecular gases H2, O2, N2, CO2and CH4

Abstract
A slow positron beam time-of-flight system employing a localised scattering cell has been used to measure total cross sections for positrons in the energy range 15-600 eV in H2, O2, N2, CO2 and CH4. The values obtained are higher than the measurements of Coleman et al. (1974, 1975 and 1976 private communication) at all energies. This confirms that those results were not fully corrected for forward scattering and are therefore superseded by the present data. There is now good agreement between the new data and those of Kauppila et al. (1977) for H2, N2 and CO2 in the region where there is an energy overlap between the two experiments.