Collisional double ionization of H-

Abstract

We have measured the laboratory double-differential cross sections for electrons from the double ionization of 0.5-MeV ${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$ in collisions with He. These data have been transformed into the projectile (${\mathrm{H}}^{\mathrm{\ensuremath{-}}}$) frame and the angular distributions of electrons (with a given energy in the projectile frame) were generated. It was found that, for all energies above 0.1 eV in the projectile frame, the angular distributions were anisotropic with a maxima at 0\ifmmode^\circ\else\textdegree\fi{} and 180\ifmmode^\circ\else\textdegree\fi{} and a minimum in between. We have also integrated these angular distributions over the solid angle and show an overall energy distribution of electrons produced by this double-ionization process.