Theory of detour transitions in radiative electron capture

Radiative orbital electron capture by the atomic nucleus

“…The measured intensity of the REC spectrum [11] was found to be smaller by a factor of 4 than the value predicted by the model of Zon leaving no room for the nuclear contribution, in contradiction with results of Ref. [9].…”

“…Following the generally adopted convention [3,4,9], we calculate the ratio of radiative to nonradiative capture rate. Then, the resulting photon spectrum accompanying the 1S capture is given by…”

Radiative electron capture in the first-forbidden unique decay ofKr81

“…It was argued that such a nuclear contribution is particularly significant in the case of 1u decays, where the combination of an allowed GT EC decay with a nuclear E1 γ transition, may compete with the direct nuclear 1u transition accompanied by an IB photon. Apparently, for the case of 41 Ca this hypothesis could fully account for the missing intensity found by the experiment [5,6]. Surprisingly, in another case of 1u REC-the decay of 204 Tl [8]-the opposite situation was observed.…”

“…To explain this finding, a hypothesis of the so-called detour transitions was considered by Kalinowski and co-workers [5,6] following an idea of Ref. [7].…”

Evidence for the virtualβ−γtransition inNi59decay

“…The experiment delivers the absolute value of this ratio as a function of the photon energy, which is compared without any normalization to the theoretical prediction which does not have any adjustable parameters. Kalinowski et al [26,27] made an attempt to extend the Zon and Rapoport model by adding the "detour" transitions via virtual nuclear states following ideas of Ford and Martin [16], but repeated the same invalid approximations as Zon and Rapoport. He was able to reproduce the spectrum of 41 Ca at the cost of adding a phenomenological parameter [26], but his model failed in case of 204 Tl [25].…”