The scattering of s-wave positrons by helium

Abstract
An attempt is made to reproduce theoretically the results of recent measurements of low-energy positron-helium total cross sections by Kauppila et al. (1976) which disagree with the earlier experimental results of Canter et al. (1973) for positron energies below 6 eV. Positron-helium s-wave phaseshifts are calculated for a 14-term helium wavefunction. The results are only very slightly different from those obtained by Humberston (1978) for a less accurate helium wavefunction, and give cross sections in good agreement with the values of Canter et al. A significant discrepancy therefore remains between the theoretical cross sections presented here and the experimental results of Kauppila et al. which, it is claimed, cannot be resolved by further improvements in the theoretical results.

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