A ten-channel eikonal treatment of differential and integral cross sections and of the (lambda, chi) parameters for the n=2 and 3 excitations of helium by electron impact

A ten-channel eikonal treatment of the n=2 and 3 collisional excitations of helium by incident electrons with energy E(eV) in the range 40<=E<=500 is performed. Differential and integral inelastic cross sections are obtained, together with theoretical predictions of the (lambda, chi) parameters which provide, as functions of scattering angle theta and E, the orientation and alignment vectors and the circular polarization fraction of the radiation emitted from the n1P levels. The results are in satisfactory agreement with recent measurements. (author)