Angular correlation parameters for the electron impact excitation of the 21 P and 31 P states of helium using first-order many-body theory

A simplified form of the first-order many-body theory was used for the calculation of the coherence and correlation parameters for the excitation of the 2¹ P and 3¹ P states of helium. The excited state wave functions were calculated numerically in the fixed core Hartree-Fock(HF) approximation. The ground state wave function was used in the HF approximation. Scattering orbitals were calculated numerically in the static exchange approximation. Calculations were performed forE=29.6, 40, 50, 60 and 80 eV impact energies for the 2¹ P state, and forE=50 eV and 80 eV for the 3¹ P state. Results for the coherence and correlation parameters are compared with the experimental values obtained from electronphoton coincidence experiments, and with other theoretical results.