ELECTRON CAPTURE CROSS SECTIONS

Abstract

Electron capture cross sections are calculated in the first Born approximation for alpha particles passing through hydrogen and singly charged helium ions passing through helium using the complete interaction Hamiltonian. Estimations of captures into excited states are made with the help of the partial cross sections obtained in a simple closed form using only the (incident ion)−(electron) interaction. The results indicate that the first Born approximation, using the complete interaction, is quite adequate in the velocity range given by [Formula: see text]. An impact parameter calculation for protons in hydrogen shows that the cross section obtained using only the (incident ion)–(electron) interaction gives unphysical results at low velocities [Formula: see text], and that most of the contribution to the cross section arises from impact parameters p > a0, where a0 is the radius of the first Bohr orbit in hydrogen.