Electron impact double ionization of Ba and Ba+

Electron impact double ionization cross-sections for Ba and Ba⁺ have been calculated in the binary encounter approximation. Hartree-Fock velocity distribution has been used for the first ejected electron and a hydrogenic velocity distribution for the second. For Ba⁺ the focusing effects of the target ion on the incident electron have been incorporated in the calculations. Contributions from ionization-autoionization to the ionization cross-sections, as observed in experiments, have been included in the present work. The calculated results show structures as observed in recent experiments.