Excitation of 31,3 P and 31,3 D states of helium from the ground 11 S state by electrons and positrons

A systematic theoretical study is carried out for the electron and positron impact excitation of the 3^1,3 P and 3^1,3 D states of helium from the ground 1¹ S state. The results are reported for the differential cross sections, Stokes parameters and alignment and orientation parameters. To calculate the scattering amplitude which relate these parameters, a distorted wave approximation theory with different choices of distortion potential has been used. The results are compared with available theoretical and experimental data in the energy range of 40–100eV.