MECHANISMS OF DOUBLE-IONIZATION OF ATOMS BY ELECTRON-IMPACT

Recent high-energy (e,3e) experiments indicate that the one-step mecha nism (shake-off process) is insufficient. We have performed an ab init io calculation that takes into account all the two-step mechanisms of double ionization. This calculation uses the second Born approximation and correlated wave functions for the initial bound state. We show th at the two-step processes are not negligible and must be added to the one-step process with the production of interference terms.