Positron-helium scattering cross sections at low energies

Experimental determinations of the elastic scattering cross sections for 2-18 eV positrons in helium have been made using a time-of-flight system specifically designed to achieve statistically accurate low-energy measurements. The cross sections are in close agreement with those of Kauppila et al. (1976) but differ at positron energies below 6 eV from the earlier measurements of Canter et al. (1972) and from the recent theoretical results of Campeanu et al. (1977).