ABSOLUTE TRIPLE DIFFERENTIAL CROSS-SECTION MEASUREMENTS IN ENERGY SHARING KINEMATICS AND A COPLANAR ASYMMETRIC GEOMETRY AT 100 AND 200 EV ON HE

Results of measurements for electron impact ionization of atomic helium are reported for energy-sharing kinematics in a coplanar asymmetric geometry. Incident energies of 100 eV and 200 eV are considered and comparison with previous experiments in fully symmetric kinematics allows the results to be put on an absolute scale. The cross-sections are compared with those obtained from two variants of the distorted wave Born approximation (DWBA) model. Good general agreement is obtained for the form of the angular distributions. The absolute magnitude of the cross sections is however not compatible with the choice of half-on-shell Coulomb T-Matrix currently used in the distorted wave impulse and related approximations.