Total cross sections are presented for the production of various stages of multiple ionization of the target in coincidence with the final projectile charge state for collisions of F6+ with Ne at 10 and 15 MeV. In particular, the current measurements are compared with the results of a new classical trajectory Monte Carlo method in which electrons are included explicitly on both target and projectile ( ~C T M C ) and with those based on the conventional independent electron model ( I E M ) . It is shown by the good agreement with experiment that the n C T M C model simultaneously represents well the ionization, charge transfer and excitation channels for both target and projectile. Further, it is demonstrated that the I E M is in clear disagreement with the present experiment and is inadequate to predict the outcome of such multi-electronic transition processes. However, the IEM is shown to provide a reasonable estimate of the free electron production, that is, the cross section summed over charge states weighted by the number of electrons liberated. The I E M is also used to illustrate a process in cusp electron production where electrons are interchanged between the target and projectile.

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Multiple ionisation cross sections u (q) for the production of recoil ions in charge state q by 120 MeV U-' U90+ impact have been measured for Ne, Ar and Kr targets using a recoil-ion-projectile-electron triple-coincidence technique. The data are compared with previously measured cross sections for U-ion impact in the projectile energy (E,) range from 1.4 to 420 MeV U-'. For low recoil-ion charge states a (q) decreases over the whole E , range somewhat more slowly than l/E,, whereas for higher recoil-ion charge states a (q) reaches a maximum at about 10-15 MeVu-'. The data are nicely described by parameter-free n-body Classical Trajectory Monte Carlo (~C T M C) calculations. The calculations indicate the importance of accounting for the Auger events in the description of the multiple ionisation process. Because of the smooth E , dependence of "(4) towards high E , , the development of a recoil-ion source using a primary U-ion beam in a storage ring for the production of high charge state recoil-ions appears to be feasible.

Abstract. For the collision systems 1.4MeVu-' U3'+ and 5.9 MeVu-' U65+ on Ne, transverse (with respect to the beam axis) momentum distributions of recoiling target atoms have been measured applying a time-of-flight technique. In the case of isotropic electron emission, the transverse momenta of the recoil ion pRL and the projectile ppl after the collision are identical. This allows the transformation of measured pRl distributions into projectile related differential scattering cross sections du/d8. Using such an analysis, we have measured differential cross sections in the scattering angle regime of 1 x r a d s 8 G 4 x rad. The shape, as well as the absolute magnitude of the derived experimental d a / d 8 is in reasonable agreement with Rutherford differential cross sections at large 8 using a projectile nuclear charge of 2, = qp and a target nuclear charge of Z, = 5. For 8 6 1 x rad, n-body classical trajectory Monte Carlo (nCTMC) calculations predict that the balance between pRl and ppI is strongly influenced by the momenta of anisotropically emitted ionised electrons. From the comparison between the derived experimental cross sections d a / d 8 with the theoretical values, as well as from the agreement between experimental and theoretical transverse recoil-ion momentum distributions, we conclude that the momenta of the ejected electrons have a considerable influence on the scattering dynamics of the heavy nuclei. Furthermore, the calculations indicate that the projectile is scattered to negative angles at impact parameters of b 3 3a0 due to anisotropic electron emission and strong polarisation of the target electron cloud by the Coulomb potential of the projectile. The possibility of rainbow scattering at 8 = 1 x rad is predicted.