High-resolution, low-energy positron scattering from helium: measurements of the total scattering cross section

Abstract

We present high-resolution (80 meV FWHM) measurements of the positron-helium total cross section in the energy range between 1 and 15 eV. The absolute magnitude of the cross section is in excellent agreement with recent state-of-the-art theoretical calculations and with previous absolute measurements (e.g. Mizogawa et al). Specific scans in the 1-3 eV and 5-8 eV energy regions reveal no evidence of the structures in the cross section reported by Karwasz et al.