Single ionization of He by energetic protons in a parabolic quasi-Sturmians approach

Fully differential cross sections for single ionization of helium induced by 1 MeV proton impact are calculated using a parabolic convoluted quasi-Sturmian (CQS) method. In the framework of this approach the transition amplitude is extracted directly from the asymptotic behavior of the solution of an inhomogeneous Schrödinger equation for the Coulomb three-body system (e^-, He⁺, p⁺). The driven equation is solved numerically by expanding in convolutions of quasi-Sturmians for the two-body proton-He⁺ and electron-He⁺ systems. It is found, at least in the high energy limit, that the calculated cross sections within the proposed CQS method converge pretty fast as the number of terms in the expansions is increased, and are in reasonable agreement with experimental data and other theoretical results.