Mapping of the Bethe surface in single-ionization ion-atom collisions

The three-body Coulomb problem is explored using classical-trajectory Monte Carlo and continuum distorted-wave methods that include all interactions, including the nuclear-nuclear term. Calculations for low-energy electron emission as a function of projectile deflection, the Bethe surface, are compared with experiment for single ionization of He by 100 MeV u-1 C6+ and 3.6 MeV u-1 Au53+. Good agreement is realized for the C6+ system. For Au53+ poor agreement with experiment is obtained, indicating that the proposed lack of the nuclear-nuclear interaction is not the source of the discrepancy. The calculations further show that significant cross sections at large projectile deflections are only realized for double ionization, not single ionization. (author). Letter-to-the-editor