Date of Award


Degree Name

Master of Arts



First Advisor

Dr. John A. Tanis

Access Setting

Masters Thesis-Open Access


Single and double ionization of helium by highly charged sulfur projectiles is investigated over an energy range of 0.16 to 1.6 MeV/u. Absolute cross sections for the processes of pure ionization, ionization associated with single capture, and ionization associated with single loss by S6,13+ projectiles were experimentally determined and compared with previous results and theories. Ratios of double-tosingle ionization for each outgoing projectile charge state were also determined and compared with theory. The pure ionization ratios for S6+ at the highest energies investigated show the q2/E dependence predicted by Knudsen et al. (1984). For S13+ the charge and velocity range studied lies outside the perturbative two-step regime so that double ionization cannot be described satisfactorily within the existing theories. Furthermore, it has been found that for both charge states double ionization is significantly enhanced when target ionization is accompanied by projectile electron capture or loss.