Electron-impact double ionization of magnesium

Theory and experiment are compared for the electron-impact double ionization of Mg. Direct ionization cross sections, involving the simultaneous ionization of both 3s electrons, are calculated using a non-perturbative time-dependent close-coupling method. Indirect ionization cross sections, involving the ionization of either a 2p or 2s electron followed by autoionization, are calculated using a perturbative time-independent distorted-wave method. At low energies the direct ionization cross sections are found to be in good agreement with experiments, while at the higher energies the indirect ionization cross sections are also found to be in good agreement with experiments. (Some figures in this article are in colour only in the electronic version)