Simple model for the ionization of helium atoms by fully and partially stripped ions in the strong interaction region

Theoretical calculations employing the modified over-barrier model to investigate single and double ionization cross sections of helium in collisions with highly charged ions are presented in the strong perturbation region. It shows the velocity and charge state dependences of cross sections, which coincides with the available experimental data. In order to determine the reliability of this model for partially stripped projectiles, the cross-section ratios have been measured for CZp+, OZp+-He (Zp=1-4) by the coincidence technique in the velocity range of 1-4.5 a.u. The calculated results are approximately in agreement with the experimental data.