Single and double ionisation of He and Ar by far H0 and H- projectiles

Abstract

Cross sections for single and double ionisation of He and Ar by impact of H0 and H- projectiles have been measured in the energy range 0.5-2 MeV. By a coincidence technique, the authors differentiated between all possible final charge states of the projectile. The total cross sections for single ionisation compare reasonably well with predictions of the free-collision model. Further, the ratio between the total double- and single-ionisation cross sections is in good agreement with predictions of the free-collision model, which is based on known cross section ratios for proton and electron impact. Thus, to a large extent, ionisation processes involving fast structured projectiles (H0 and H-) can be understood on the basis of collision properties of the constituent particles (e- and p+) of the projectile.