Rhg. Reid et al., INITIAL-STATE, FINAL-STATE AND HIGHER-ORDER EFFECTS IN ELECTRON-IMPACT IONIZATION OF HELIUM-ATOMS, Journal of physics. B, Atomic molecular and optical physics, 31(3), 1998, pp. 563-571
An approximate method to include second-order effects in the treatment
of electron impact ionization processes within a combined distorted w
ave Born approximation (DWBA)+R-matrix approach is presented. The sens
itivity of the results for tri?le differential cross sections for elec
tron impact ionization of helium to the description of the initial and
final states, and to the inclusion of second-order effects within the
R-matrix box, is analysed. It is found that changes in the representa
tion of the initial bound state have the strongest effect on the theor
etical predictions.