Single and Double Ionization of He by Fast Light Ions

The cross sections for single and double ionization of He by H, He, Li, B, C and O ions were measured. The ion velocity ranged from ~ 2 vo to ~ 10 vo. The Bethe-Born results of Gillespie and Inokuti are found to be in good agreement with the data for single ionization at low projectile charges. The breakdown of the perturbation region is discussed and in the strong interaction region the experimental single ionization data are compared with results of Bohr and Janev. The double ionization data are presented and a theoretical estimate based on an independent electron model is discussed.