DIFFERENTIAL CROSS-SECTIONS AND ELECTRON-IMPACT COHERENCE PARAMETERS FOR ELECTRON-SCATTERING FROM HELIUM-ATOMS

We have applied the R-matrix with pseudo-states method (RMPS) to study electron-helium scattering at intermediate energies. Differential cro ss sections for elastic and inelastic collisions and electron-impact c oherence parameters for excitation of the 1(1)S --> 2(1)P(o) transitio n are presented for incident energies of 30, 50 and 80 eV. Excellent a greement with experiment and with the predictions of the convergent cl ose-coupling calculation by Fursa and Bray is obtained. Since correlat ion effects and target continuum states are both accurately represente d in a completely general way by this method, the associated program p ackage can now be used to obtain reliable results at intermediate ener gies for arbitrary complex atomic and ionic targets of importance in a pplications.