EXCITATION OF HELIUM BY FAST ELECTRONS

A six-parameter ground-state wave function and modified hydrogenic excited-state wave functions are used to calculate the first Born approximation cross section for electron excitation of the ground state of helium to the n1P (n = 2 to 6) and n1D (n = 3 to 6) states. Calculations are carried out using both the length and velocity formulations of the Born approximation integrals and these show that the total cross sections are accurate to about 4%. The total and differential cross sections are compared with other calculations and with experiment. At large electron impact energies the theoretical and experimental total cross sections do not agree.