Coupled-channel calculations of fully differential cross sections for ionization in 75-keV collisions
Phys. Rev. A 112, 032806 – Published 12 September, 2025
DOI: https://doi.org/10.1103/czd2-865z
Abstract
The fully differential cross section is the most detailed quantity that can be measured or calculated to study ionization in few-body systems. For 75 keV proton collisions with helium, various experimental data are available. However, previous theoretical calculations found significant discrepancies across the entire range of data. In this work the wave-packet convergent close-coupling method is extended to calculating these cross sections for electrons ejected with energies from 1 to 75.4 eV. The approach utilizes a two-center expansion and correlated two-electron helium wave functions to describe the four-body proton-helium system. While there is good agreement with the experiment for electrons ejected with energies near the matching-velocity point, elsewhere, the results overall do not support the picture provided by the available measurements. Hence, further investigations, both theoretical and experimental, are necessary to resolve the intermediate-energy proton-helium differential ionization problem.
