Differential Elastic Scattering of Positrons from Argon Atoms at Low Energies

Abstract
We have measured relative cross sections in the angular range of 26° to 65° at 8.5 and 30 eV. Our 30-eV data show a monotonic increase with decreasing scattering angle, in disagreement with three theoretical calculations which predict a structure of the cross section in this range, but in qualitative agreement with a prediction of Joachain and Potvliege, derived from optical-potential calculations at and above 100 eV. At 8.5 eV, below all inelastic thresholds, our data agree very well with the theoretical results of McEachran and Stauffer as well as Nakanishi and Schrader but disagree with other calculations.