Single and double ionization of He by 0.5-8 MeV/q Liq+ (q = 1, 2, 3) ions

Single and double ionization of He by Liq+ projectiles (q = 1,2,3) have been investigated in the energy range 0.5-8 MeV/q. Target ionization associated with specific outgoing projectile charge states was identified using time-of-flight techniques. The primary goal of this work was to investigate the ionization of He by `structured' projectiles and to determine the effect of the projectile electrons on the ionization process. For all energies investigated, the double-to-single ionization ratios associated with electron capture and loss are significantly larger than those for direct ionization (no projectile charge change). The direct double-to-single ionization ratios are largely independent of the incoming projectile charge state, apparently depending only on the nuclear charge. For single-electron capture and single-electron loss, the ratios depend quite strongly on the incoming projectile charge state, however.