Double- and single-differential and total ionization cross sections for electron-impact ionization of a helium atom.

Abstract

Double, single, and total ionization cross sections have been calculated for the single ionization process of an electron-helium atom system for the incident energy range (50{endash}300 eV) including the electron exchange effect. The final-state wave function involves a correlated three-body Coulomb continuum, and satisfies the three-body asymptotic boundary condition. The electron exchange effect is found to play a dominant role for near-symmetric and symmetric geometries. All results have been compared with available experiments, and reasonably good agreement has been noted except for low incident energies (e.g., 50 eV) and low ejected energies (in the double-differential or single-differential cross-section level). {copyright} {ital 1996 The American Physical Society.}