Generalized oscillator strengths for the ionization of helium by protons, calculated with the classical three-body collision theory

Differential cross sections and generalized oscillator strengths fE(q) for ionization of helium by 100 and 300 keV protons have been calculated, using a classical three-body collision theory, in which the momentum transfer to the atomic nucleus has been eliminated. Comparisons are made with the results of the scaled first Born approximation and the binary encounter theory. The calculated generalized oscillator strengths depend upon the energy of the incident proton. There is a marked difference between the present results and the other two theories for small energy transfers.