Accurate first Born approximation cross sections for the excitation of helium by fast electrons

Abstract

Accurate first Born approximation cross sections are given for the electron impact excitation of the ground state of helium to the n1S (n = 2 to 7), n1P (n = 2 to 6) and n1D (n = 3 to 6) excited states. Many-parameter correlated wave functions for both the initial and final states have been employed in the length formulation of the Born approximation integrals to obtain cross sections for excitation to the n1S (n = 2 to 7), n1P (n = 2, 3, 4) and 3 1D states. Calculations have also been performed in both length and velocity formulations using a six-parameter ground-state wave function and unrestricted Hartree-Fock excited-state wave functions. The results are compared with other calculations and with experiment.