TRANSFER AND IONIZATION PROCESSES DURING THE COLLISION OF FAST H+, HE-2+ NUCLEI WITH HELIUM

Total cross sections for single electron capture, single ionization, resonant double capture and transfer ionization processes during the collision of H+, He-2+ nuclei with helium are calculated within the continuum distorted wave approximation for the energy range 100-1600 keV amu-1. The semiclassical independent-event model of the collision is adopted, while the effect of electron correlation in the helium atom is explicitly accounted for by the use of a two-electron model of the helium ground state developed by Pluvinage. For all but the lowest energies considered, results for single capture, single ionization and resonant double capture are typically one-third to two-thirds those of experiment. The discrepancies may be attributed to contributions from capture into excited states and from simultaneous capture/ionization and excitation processes, which have not been included in the calculations. Results for transfer ionization however are considerably larger than those of experiment, indicating the inadequacy of the rather simplistic model used to describe this process. Corrections to results for single and resonant double capture presented by Crothers and McCarroll in an earlier paper are also given.