Approximate first Born descriptions of high-energy asymmetric (e,2e) cross sections for helium

Abstract

The absolute experimental (e,2e) cross sections for electron impact single ionisation of helium atoms at an incident electron energy of about 8 keV were measured by Lahmam-Bennani et al. (1983) using an asymmetric geometry. These results are utilised to test various wavefunctions describing the ejected electron when employed in the factorised plane-wave first Born approximation. The results indicate that the use of a Coulomb wavefunction, constructed to be orthogonal to the wavefunction describing the ejecting orbital and assuming an effective charge of +1.05 for the ion formed by the collision, is adequate to describe quantitatively all the important features of the absolute experimental results.