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Abstract

In the first part of this work the mutual ionization of target and projectile in collision of a He-target with an H--projectile at 200 keV was investigated in a kinematically complete experiment. The emitted electrons as well as the target ion were detected in coincidence with the ionized projectile. This experiment represents the most detailed measurement of fully di erential cross sections for mutual ionization. It could be shown in comparison with theoretical predictions and latest (e,2e) experiments, that the ionization of the target can be described in terms of a pure electron-electron interaction. On the other hand, the ionization of the H--projectile revealed large discrepancies between theories and the performed experiment. None of the existing theories can describe the properties of this four-body system in order to account for the behaviour of the electrons emitted from the H--projectile. In the second part of this work a target of cold atomic hydrogen was developed and built up. Since atomic hydrogen is the simplest atom, which can be described analytically, it is now possible for the rst time to study experimentally the dynamics of three-body systems in detail using ion-atom collisions.