Secondary electrons ejected from He by protons and electrons

Abstract

Experimental data on the energy distribution of secondary electrons ejected from He by fast protons and electrons are shown to exhibit the following features expected from the Rutherford theory and the Born approximation: (a) the energy distribution of slow secondary electrons resembles in shape that deduced from the photoionization cross-section. (b) The energy distribution for fast secondary electrons converges to that predicted by the Rutherford theory for proton impact and by the Mott theory for electron impact. (c) The cross-sections for fast protons are very similar to those for electrons with the same velocity as the protons. Comparison with the optical data indicates that some minor but systematic corrections on the experimental data are necessary. The corrected experimental data are consistent with the total ionization cross-section.