One- and two-electron-loss cross sections from fast He-ions in hydrogen, helium and argon

The single- and double-electron-loss cross section for He - ions passing through H 2 , He and Ar gas targets have been studied in the impact-energy range from 100 keV to 3 MeV. He - ions were formed from He + by charge transfer in a gas cell and the cross sections were determined by the initial-growth method. The experimental results for single-electron loss are compared with theoretical estimates based upon the semi-empirical classical impulse approximation of Bates and Walker (1966). For H 2 and Ar targets, theory and experiment agree well within experimental error while the present results for He targets are 20% higher than the theoretical values.