Ionization excitation of helium by the (e,2e) reaction

The (e,2e) cross sections for transitions to the n=1, 2, and 3 final state of He+ have been measured at impact energies of 1000 and 1600eV by using a newly developed energy and momentum dispersive spectrometer. Binding energy spectra in the range of 8to86eV and momentum profiles for the transitions to the ground and excited ion states of He+ are reported at different impact energies, and the experimental results are compared with plane wave impulse approximation calculations. The impact energy dependence of cross section ratios for the He+n=1, 2, and 3 final states are obtained. Some discrepancies are observed between experimental data and theoretical calculations.