Time-dependent close-coupling studies of the electron-impact ionization of excited-state helium

The time-dependent close-coupling theory is applied to the study of the electron-impact ionization of helium from the excited $(1s2s)$ configuration. Calculations are made in an effort to resolve the discrepancy between theoretical calculations and existing experimental measurements for this cross section. We find good agreement with the existing convergent close-coupling calculations of Bray and Fursa [J. Phys. B 28, L197 (1995)], but are in substantial disagreement with the experimental measurements of this quantity by Dixon et al. [J. Phys. B 9, 2617 (1976)].