Double-differential cross sections for single ionization of helium by bare ion impact

Double-differential cross sections (DDCS) for single ionization of helium by impact of proton and highly charged carbon ion have been calculated in the framework of four-body formalism using the three-Coulomb wave model (3C-4B) and first Born approximation (FBA-4B), respectively. The correlated motion of the particles interacting through long-range Coulomb potential is properly taken into account in the final state. In this paper, the energy and angular distributions of DDCS of low- and high-energy electron emission for ground-state helium atoms have been investigated. The ejected electrons are affected by the two-center field of the target and the projectile ion. The two-center effects are confined to comparison with other theoretical results. The results obtained, both from the 3C-4B and FBA-4B models, are compared with other theoretical and experimental findings. The present results are found to reproduce the peak structure of the experimental observations. Large discrepancy occurs between the present two theories at forward and backward angles except about the emission angle 90°. The present computed results obtained by the 3C-4B model are in good agreement with the available experimental findings.