Autoionizing Double Capture in N 7+ on Helium Collisions at Low Energies

We have studied the branching ratios between the single-electron capture and the double-electron capture for the N 7+ -He collision at the keV a.m.u. -1 impact energy range. A good agreement has been found with the experiments for these ratios as well as for the differential cross-sections corresponding to the various processes which occur during the collision. The present study does not support the conclusions of another theoretical work concerning the mechanism leading to the single-electron capture. As for the populations of the N 5+ (3 l , 3 l ') substates formed by double capture, there is a fairly good agreement between both theory and experiments.