Double differential cross sections for electron impact ionization of helium at low energies

Abstract

The double differential cross sections for electron impact ionization of helium at incident energies of 50, 40 and 32.6 eV have been calculated in the DS3C model. The present results are compared with the absolute measurements and the theoretical ones of the convergent close-coupling (CCC) method. It has been found that by multiplying fixed factors for fixed incident energies, the present results are in good agreement with experiment, while for the CCC method different scaling factors are required for different secondary energies even if the incident energy is fixed. In addition, the present results at high incident energies are also given for comparison with those of CCC.