A systematic theoretical study is carried out for the electron and positron impact excitation of the 31,3P and 31,3D states of helium from the ground 11S 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.
