Charge-changing processes in small-impact-parameter collisions betweenO+qand rare gases

We have studied the charge distributions of oxygen ions after small-impact-parameter collisions with Ne, Ar, Kr, and Xe gases. Bombarding energies in the 10-30-MeV range and incoming charge states between $4^{+}$ and $7^{+}$ were scattered to angles between 5° and 8° in a single collision process. The measurements indicate that for the heavier gases an equilibrium charge distribution is obtained after a single collision. Interpretation of the experimental results on the basis of a statistical "compound-atom" model is suggested.