Coupled-Sturmian and perturbative treatments of electron transfer and ionization in high-energyp-He+collisions

Cross sections have been determined for electron transfer and ionization in collisions between protons and ${\mathrm{He}}^{+}$ ions at proton energies from several hundred kilo-electron-volts to 2 MeV. A coupled-Sturmian approach is taken, extending the work of Winter [Phys. Rev. A 35, 3799 (1987)] and Stodden et al. [Phys. Rev. A 41, 1281 (1990)] to high energies where perturbative approaches are expected to be valid. An explicit connection is made with the first-order Born approximation for ionization and the impulse version of the distorted, strong-potential Born approximation for electron transfer. The capture cross section is shown to be affected by the presence of target basis functions of positive energy near ${\mathit{v}}^2$/2, corresponding to the Thomas mechanism.