Differential cross sections for electron impact 11S-23S excitation in helium

Abstract

Differential cross sections are calculated for the electron impact excitation of 11S-23S transitions in helium at incident energies of 100 and 200 eV. A distorted wave approximation is used with the effect of target polarization taken into account. The results are compared with the experimental data of Sakai et al. (1991) and with the R-matrix method calculation of Nakazaki et al. (1991). The present cross section is in general agreement with the R-matrix calculation. However, the present calculation cannot reproduce the very large cross section obtained by Sakai et al. in the forward direction at 200 eV.