Electron excitation functions for the 23S, 21S, 23P and 21P states of helium between the n=2 and n=3 excitation thresholds

The differential cross sections for excitation of the ground state of helium to the 2 3 S, 2 1 S 2 3 P and 2 1 P states is calculated using the R-matrix method of Berrington et al. (see ibid., vol.8, p.1459 (1975)). Results are presented at electron scattering angles of 30, 60, 90 and 120 degrees from the excitation threshold up to about 22.4 eV. The calculations are compared with the absolute differential cross section measurements of Pichou et al. (see ibid., vol.9, p.933 (1976)).