Nuclear-resonant electron scattering

We investigate nuclear-resonant electron scattering as occurring in the two-step process of nuclear excitation by electron capture (NEEC) followed by internal conversion. The nuclear excitation and decay are treated by a phenomenological collective model in which nuclear states and transition probabilities are described by experimental parameters. We present capture rates and resonant strengths for a number of heavy-ion collision systems considering various scenarios for the resonant electron-scattering process. The results show that for certain cases resonant electron scattering can have significantly larger resonance strengths than NEEC followed by the radiative decay of the nucleus. We discuss the impact of our findings on the possible experimental observation of NEEC.

Figure 1

(Color online) NEEC recombination mechanism of a continuum electron into the $K$ shell of an initially bare ion, followed by IC of the excited nucleus. The nuclear transition from the ground state $G$ to the first excited state $E$ is pictured schematically on the right-hand side of each panel.

Figure 2

(Color online) NEEC recombination mechanism of a continuum electron into the $L$ shell of an initially bare ion, followed by fast x-ray emission from the electronic decay to the $K$-shell ground state. The process is completed by IC of the excited nucleus. See text for further explanations.