Energy and Angular Distributions of Electrons from Ionization Excitation of Helium by Proton Bombardment

Double-differential cross sections (ddcs), relative to ejection energy and angle, have been calculated for electrons emitted from helium by proton bombardment for all excited states of the resulting helium ion through the third hydrogenic shell. Comparable calculations were made by using both a 12-term correlated wave function and a product of one-electron wave functions for the initial state of the helium atom. Results are presented for an incident proton energy of 300 keV with various ejection energies and angles. The effect of the correlated wave function was significant for cases involving excitation to the $P$ states. The contribution from these states represented an appreciable percentage of the total ddcs over all states for low and intermediate ejection energies, which was not indicated by the corresponding results from the uncorrelated wave function.