Atomic charge exchanges in close collisions between Nsup(+q) ions and gas targets in the MeV energy range

Charge state distributions of nitrogen ions after small impact-parameter collisions with nitrogen, neon, argon, krypton and xenon gases were studied. The projectiles with kinetic energies between 1.5 and 3.0 MeV and incident charge states between 1sup(+) and 5sup(+) were detected after scattering under single-collision conditions to angles between 0.2 degrees and 4.0 degrees. Details of the experimental set-up established in a 1.1-m diameter off-set scattering chamber are described. The results indicate that after a single close collision, the outgoing charge distributions are rather insensitive to the value of the incoming charge, the scattering angle and the target gas. Comparison with the prediction of the statistical 'compound atom' model indicates that the good agreement for the observed shapes of the outgoing charge state distributions and their average values for lower energies worsens for higher energies and heavier targets. This can be qualitatively accounted for by the possibility that under the latter conditions the randomization assumed by the model was not achieved