Abstract
In the course of this work transfer ionization (TI), radiative electron capture (REC), and single
ionization (SI) in fast ion-helium collisions have been studied. For this purpose, two experimental
techniques, a 4π coincident ion-electron momentum spectrometer, namely a Reaction
Microscope (REMI) and the heavy ion storage ring TSR, providing excellent beam properties,
have been combined.
In TI, i.e. the ejection of one plus the capture of a second target electron, the role of electronelectron
correlations is of particular interest. In order to unravel different correlated as well as
uncorrelated mechanisms, differential data has been recorded for different perturbations (projectile
charge to speed ratio). For the first time strong evidence of a recently proposed, correlated
TI process was found experimentally.
In a second, pioneering experiment it has been attempted to perform the first kinematically
complete measurement on REC. Here, an electron from the target is captured by the projectile
simultaneously emitting a photon. In order to observe the emerging photons, a detector
covering a large solid angle has been designed and implemented in the REMI. Although three
particle coincidences have been recorded between recoil ions, projectile ions, and photons, experimental
proof of the acquisition of REC coincidences was prevented due to limited statistics.
Finally, in studies on SI, the influence of the projectile beam coherence properties on the collision
dynamics has been investigated. The pronounced differences to earlier data taken with
a projectile beam with much smaller coherence length provide evidence for its influence on
the ionization dynamics, which is generally neglected in theoretical calculations. These results
could pave the way to a final resolution of the long standing question on the origin of the
discrepancies between theory and experiment in fully differential cross sections
