Hannover 2013 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 30: Poster: Interaction with VUV and X-ray light

A 30.5: Poster

Mittwoch, 20. März 2013, 16:00–18:30, Empore Lichthof

Isomer depletion via photons and electrons generated by an XFEL pulse — •Jonas Gunst, Adriana Pálffy, and Christoph H. Keitel — Max-Planck Institut für Kernphysik, Heidelberg

Long-lived nuclear excited states also known as isomers can store large amounts of energy over long periods of time. Much interest arises from a number of fascinating potential applications related to the controlled release of nuclear energy on demand, such as nuclear batteries. Here we investigate the controlled depletion of the 2.4 MeV ^93mMo isomer via the excitation of a 4.8 keV transition to an above lying triggering level that then decays via a fast cascade to the ground state.

As excitation mechanisms we consider the competition between photoexcitation and the coupling to the atomic shell in the process of nuclear excitation by electron capture (NEEC). A brilliant x-ray free electron laser (XFEL) source delivers the resonant photons for photoexcitation and simultaneously produces the electron plasma [1] which provides the free electrons and charged ions necessary for NEEC. Based on the semi–classical Maxwell–Bloch equations and perturbation theory we present numerical results for reaction rates of isomer depletion. While the photoexcitation cross section is typically two orders of magnitude smaller than the NEEC one for the 4.8 keV transition [2], we show that the efficiency of the NEEC process is in our case limited by the available charge states and the electron temperature in the plasma.

[1] S. M. Vinko et al., Nature 482, 59 (2012).

[2] A. Pálffy, J. Evers and C. H. Keitel, Phys. Rev. Lett. 99, 172502 (2007).