Differential Scattering of Helium Ions on Targets of He, Ne, and Ar at Energies from 120 to 830 keV

The scattering of He⁺ projectiles by impact on the noble gases He, Ne, and Ar was investigated in the energy range 120-830 keV under single-collision conditions. Specifically, the experiment measured, as a function of angle in the range 1^∘{} -8^∘{}, the total differential scattering cross section as well as the differential cross sections for scattering without change of charge, for scattering with charge transfer, and for scattering with electron stripping. The total differential scattering cross section was found to be in agreement with a theoretical differential scattering cross section calculated classically using a screened Coulomb potential. Thus, the scattering of the particles in these close encounters is determined primarily by the mutual nuclear repulsion and may be adequately described by classical mechanics. The fraction of particles in a particular charge state was independent of the scattering angle, a result consistent with theory and with previous experiments at slightly lower energies. For the resonant case He⁺ + He, it was found that the fraction of scattered particles which had picked up an electron during the collision could be prediced by a semiempirical equation. Good agreement was also found when comparing relative charge-state populations with the predictions of a statistical theory.