Multiple ionization inHe+–rare-gas collisions

Absolute cross sections are presented for single and multiple ionization of He, Ne, Ar, and Kr resulting from ${\mathrm{He}}^{+}$ impact between 15 and 2000 keV. The cross sections are measured for collisions in which the projectile charge state is unchanged (direct ionization), decreases (single-electron capture), and increases (single-electron loss). From these data total cross sections for target-ion production, for free-electron production, and for single-electron capture are determined. The data are used to demonstrate the relative importance of the various ionization channels as they contribute to the production of free electrons. In addition, from the electron-loss data, it is deduced that electron loss by the projectile generally results in ionization of the target as well.