Doubly differential cross section for electron ejection in the plane-wave Born approximation: a hydrogenic case study

A study of the cross section for electron loss from He+ on H, which sums over all final states o the target atom (both bound and continuum) is presented. This study is used as a basis for the comparison of several closure approximations which effect an approximate sum over target final states. The qualitative structure of the doubly differential cross section depends strongly upon the specification of average energy of excitation of the target atom. Doubly differential cross sections due to electrons ejected from both the projectile and the target are presented and regions of velocity space where interference between these two processes may occur are identified. (author)