Second-order Born model for two-electron atomic ionization by fast charged-particle impact

The second-order Born theoretical model developed for describing simultaneous ionization excitation and double ionization of a two-electron atomic shell by a fast charged-particle impact, was discussed. The model measured the projectile-target interaction to the second order, whereas the interaction of the two target electrons ejected into continuum was treated nonperturbatively by the convergent close-coupling (CCC) method. The model was used to describe two-electron ionization processes with large projectile velocity, small momentum transfer, and small to intermediate energy of the ejected electrons. The model was also applied to ionization excitation and double ionization of He by electron and positron impact in kinematics.