Projectile and electron spectra resulting from positron-argon collisions

Abstract

A three-body classical trajectory Monte-Carlo calculation is used to evaluate the differential cross sections for the ejected electron, as well as the projectile scattering for 50, 100 and 150 eV e++Ar0 electron removal collisions. In the ionized electron spectra both the electron capture to the continuum (ECC) and binary peak structures are observed. The theoretical ECC peak is diffuse and shifted to lower energies than expected from simple arguments. The calculated double differential cross sections for electron ejection have been compared to experiment. When the experimental apparatus function of Moxom et al. (1992) is used to convolute the theoretical spectra, good agreement with their data is found that confirms a sharp ECC structure is not present in this system. Moreover, comparisons made at non-zero angles show substantial agreement between theory and experiment. The scattered positrons agree well with measurements made at 3 degrees by Kover et al. (1993), but differ at larger angles. In addition, the differential cross section for positronium formation is presented; no evidence of an observable Thomas peak is present.