Cross Sections for Singly Differential and Total Ionization of Helium by Electron Impact

Published

March 1, 2000

Author(s)

Yong Sik Kim, W R. Johnson, M E. Rudd

Abstract

The Binary-Encounter Dipole (BED) model for electron-impact ionization is applied to helium using the continuum dipole oscillator strength calculated from the relativistic random-phase approximation. The resulting total ionization cross section agrees with available experimental data within the quoted experimental uncertainties. The singly differential (=energy distribution of ejected electrons) cross section agrees well in shape with available experiments. Because of the remarkable agreement with experiment at all incident and ejected electron energies and the compact analytic form of the cross sections, we propose that the BED cross sections for helium serve as a normalization standard with an accuracy of {plus or minus}5% from the threshold to 1 keV the primary electron energy.

Citation

Physical Review A (Atomic, Molecular and Optical Physics)

Volume

61

Issue

No. 3

Pub Type

Journals

Keywords

differential ionization cross section, helium atom, total ionization cross section

Citation

, Y. , Johnson, W. and Rudd, M. (2000), Cross Sections for Singly Differential and Total Ionization of Helium by Electron Impact, Physical Review A (Atomic, Molecular and Optical Physics) (Accessed April 19, 2024)