Population Mechanisms of the (1s1/22p3/2) 1 P1 state of He-like Uranium Ions

The investigations of the atomic structure of He-like ions probe the understanding of the interplay of relativistic effects on the dynamics of the simple atomic few-electron systems. For two-electron high-Z ions, the formation of the excited states can be studied by the observation of the radiative decay of the excited levels to the ground state. This study can be done via different processes which give information about the population mechanism of the excited L-shell levels [1, 2]. For He-like uranium the energy difference between the two-components of the Kα1 line, the P1 and P2 states, is around 64 eV . Up to now, this energy could not be resolved experimentally due to the limited energy resolution of the germanium detectors. To populate the P1 state, two processes were studied, namely, the excitation of K-shell in He-like uranium ions and the electron capture into H-like uranium ions. For this, the measurements have been carried out using the internal gas-jet target of the experimental storage ring ESR at GSI. The x-ray emitted during the collisions of U and U with N2 atoms were detected at different observation angles with respect to the beam direction.