Collisional electron detachment ofH−by He: A target effect

Detailed measurements of the collisionally induced electron detachment of ${\mathrm{H}}^{-}$ during collisions with He at an ion energy of 0.5 MeV are reported for $\theta =0-173\mathrm{}°$. These data are compared to similar measurements using Ar as the target and to electron elastic scattering from He. These comparisons reveal that, while some characteristics of the electron energy spectra are similar for both targets, one feature shows a marked target dependence. Further experiments, in the forward direction only, using other ${\mathrm{H}}^{-}$ energies in the range 0.35-1.35 MeV, as well as ${\mathrm{D}}^{-}$ at 1.0 MeV, indicate that the results have no simple interpretation in the rest frame of the projectile.