MULTIELECTRON PROCESSES IN HEAVY ION-ATOM COLLISIONS AT INTERMEDIATE VELOCITY

Using high resolution x-ray spectroscopy, we have measured projectile electron single and multiple cross sections when a two-electron Ar16ion collides with neutral target atoms. For a fixed impact velocity (u psilon(p) = 23 a.u.), but using various targets from He to Xe, a range from the perturbative regime to the strong interaction regime has bee n investigated. Double excitation cross sections are found to be well reproduced by an independent electron model. First measurements of cap ture-ionization cross sections are also reported and show the importan ce of this often-neglected process. [S0031-9007(97)04505-5].