On the electron impact ionization of H (1s) in coplanar asymmetric geometry

Abstract

Coupled-pseudostate calculations of the triple differential cross section are reported at an incident energy of 150 eV. These are compared with previous experimental data and with a new approximation of Brauner et al. (1989) which employs an ansatz of Garibotti et al. (1980) for the three-body final state. The normalization of the experimental data has been criticized because it is obtained by extrapolation of the measurements to unphysical zero momentum transfer. It is pointed out that this only affects the overall normalization for a given ejection energy. The relative normalization for different scattering angles of the fast electron, at a fixed ejection energy, is in fact determined directly by experiment and is therefore not open to this criticism. Some previous comparisons of experiment and theory have ignored this important point. It is shown that both theories have some significant disagreements with the relative normalization of the measurements and with each other.