Capture into excited states in proton-helium collisions

Abstract

An approximate integral form of the close-coupling formalism is used to calculate the cross sections for capture of electrons from helium atoms by protons. Results for the ground-state and excited-$2s$-state capture cross sections are obtained with the effect of the proton-nucleus interaction included, and compared with experimental and other theoretical results. The effects of the post and prior forms of interaction on the cross sections are studied in detail. The effect of the exchange integral on the capture cross sections is also reported. It is found that the inclusion of the ground-state transition in calculating $2s$-state capture cross section enhances the cross section values only in the low-energy region. The present values of the capture cross sections for the ground and excited $2s$ states are in very good agreement with the experimental observations at high as well as low energies. In the low-energy region the nature of the experimental curve has been correctly reproduced for both cases. Results for the differential capture cross sections in the forward direction and the total elastic cross sections are also reported.