Simultaneous ionization and excitation of helium by electron impact

We present numerical results for He (1s²) (e, 2e) He⁺ reaction process for transitions to the n = 1, 2 and 3 states of He⁺ for noncoplanar symmetric geometry at incident energies of 1000 and 1600 eV. The calculations are performed using the plane wave impulse approximation (PWIA) and the 3C method (also called the Brauner, Briggs and Klar (BBK) model) that includes post collision interaction and multiple scattering effects. In both the methods we have used the highly correlated configuration interaction wave function for the ground state of helium. A comparison of the present theoretical cross sections with the recent measured data of Ren et al. [X.G. Ren, C.G. Ning, J.K. Deng, G.L. Su, S.F. Zhang, Y.R. Huang, G.Q. Li, Phys. Rev. A 72 (2005) 042718] shows reasonably good agreement.