Partial Ionization Cross Sections for Noble Gases Bombarded with 0.8–3.75-MeV Protons

Abstract

The partial cross sections for the production of noble-gas ions in their various charge states were determined for He, Ne, Ar, and Kr bombarded by protons in the energy range from 0.8 to 3.75 MeV. The slow ions formed in the collisions of the swiftly moving hydrogen ions with the isolated noble-gas atoms were extracted in a direction at right angles to the proton beam. Their charge and intensity were analyzed by means of a portable mass spectrometer with special constructional features. These data were combined with values of the total ionization cross sections determined by Hooper et al. to evaluate the partial cross section for the formation of each species. The cross sections are compared with those previously obtained by others for proton projectiles with energies between 5 and 180 keV.