Nuclear lifetime prolongation in resonant electron recombination processes

A. Pálffy1, Z. Harman1, C. Kozhuharov2, C. Brandau2, C. H. Keitel1, W. Scheid3, and T. Stöhlker2,4 1Max-Planck-Institut für Kernphysik, Heidelberg; 2GSI, Darmstadt, Germany; 3Justus-Liebig-Universität, Giessen; 4Ruprecht-Karls-Universität, Heidelberg The population and lifetime of nuclear excited states are affected by the electronic shells, especially in nuclear processes which directly involve electrons [1]. In particular, the lifetime of low-lying excited nuclear states can be increased by the process of nuclear excitation by electron capture (NEEC) followed by fast x-ray emission (NEECX) in highly-charged heavy ions. In the resonant process of NEEC, the collision of an ion with a free electron leads to resonant capture into an atomic orbital with simultaneous excitation of the nucleus [2]. For some heavy nuclei, NEEC into the K shell is energetically forbidden. In this case, NEEC into the L shell of bare ions will be followed by a stabilizing x-ray decay that suppresses the internal conversion channel and limits the nuclear decay rate to the γ rate, thus modifying the lifetime and population of the nuclear excited state.