MULTIPLE-SCATTERING CALCULATION FOR IONIZATION OF HELIUM-ATOMS BY ELECTRONS AT INTERMEDIATE ENERGIES

The triple differential cross section for electron impact ionisation of helium atoms has been calculated in the coplanar asymmetric geometry following the multiple scattering approach of Das. The method has already been successfully employed to describe the electron impact ionisation problem for the hydrogen atom. Here the impact energy of the incident electron is taken to be 150 and 250 eV in an intermediate energy range where there are still some discrepancies between theory and experiment. Present results are compared with the available experimental data and with two of the most recent calculations in some cases, and are found to be in reasonable accord with experiment, particularly in the binary peak region. The present calculation for 250 eV incident energy reproduces the experimental results in some cases better than other theories.