Calculations of the Energy and Angular Distribution of Electrons Ejected from Helium by Protons

Doubly differential cross sections (ddcs), for ejection of secondary electrons of various energies at various angles for helium bombarded by 50- 100-, and 150-keV protons, have been calculated and compared with the recent experimental results of Rudd and Jorgensen. Differential cross sections obtained by integrating the ddcs over all ejection angles are compared with similar results obtained from the experimental ddcs. The wave functions employed by Mapleton to calculate ionization cross sections are used in the Born approximation. General agreement between theory and experiment for the ddcs in found, but discrepancies are noted in the forward and backward directions. The integrated cross sections show good agreement over a large range of ejection energies.