Single-electron–removal processes in collisions of positrons and protons with helium at intermediate velocities

This is the authors' abstract. We don't add key points for this paper.

Total cross sections for single ionization and charge transfer have been calculated using the classical-trajectory Monte Carlo (CTMC) technique for collisions of both positrons and protons with helium. Analysis of the classical trajectories has helped to explain the differences in the collision mechanisms responsible for the observed relative magnitudes of the positron and proton electron-removal cross sections. In the intermediate collision velocity range (1.5 a.u. 4.5 a.u.) positrons and protons are found to be equally likely to singly ionize helium, but positrons remain at least half an order of magnitude more likely to remove an electron by charge transfer.