Coulomb correlations in electron and positron impact ionization of hydrogen at intermediate and higher energies

Investigating the relation between the asymptotic condition and the dynamic Coulomb correlation for single and multiple ionization the authors discuss a complete set of spatially separable N-electron final-state wavefunctions, satisfying multiple ionization boundary conditions. They apply these results to electron and positron impact ionization of atomic hydrogen in the energy range 54.4 and 250 eV on the basis of a parameter-free model formulated within the scope of the multiple scattering approach. A comparison between their results and available experimental data and alternative theoretical calculations are made and discussed. The role of exchange is also investigated. The contribution of exchange in the triple differential cross section is found to be virtually negligible whereas the asymmetry parameter A is significantly affected.