Asymmetry parameters and differential cross sections for photoionization-excitation of helium

Asymmetry parameter beta (2) for photoionization of helium leaving the Heion in the n = 2 level and differential cross sections(DCSs) in the n = 2, 3, 4 levels with photon emission angle theta = 90 degrees are provided at p hoton energies 69 - 76.8eV employing the R-matrix method with a 20-term tar get representation, in which five polarization orbitals 6l are included. Th e asymmetry parameter beta (2) and the DCS, in the n = 2 level in the regio n of 69 - 73 eV, are in good agreement with available experimental and theo retical results. Above the n = 3 threshold, we present new theoretical resu lts along with measurements. No theoretical and experimental results can be used to compare with the present calculations of the DCSs for photoionizat ion into the He+ ion in the n = 3, 4 levels.