Theoretical triple differential cross section of the helium atom ionization with excitation to the n=2 ion state

The (e,2e) triple differential cross section and generalized oscillator strengths of the helium atom ionization with simultaneous excitation have been calculated for the kinematic arrangements of the recent measurements and calculations of Dupre et al. [J. Phys. B 25, 259 (1992)]. The first Born calculation has been performed with an initial correlated multiconfiguration Hartree-Fock helium atom ground state and a coupled-channel final state of the ion and ejected ''slow'' electron. We find generally good agreement with the experiment, which is a substantial improvement on the previous calculations