Evidence for the virtual beta-gamma transition in 59Ni

TL;DR

This paper provides experimental evidence for a virtual beta-gamma transition in 59Ni decay, supported by a new theoretical analysis that matches observed gamma spectra and reveals a 4% virtual component.

Contribution

It introduces a novel theory for radiative electron capture in second forbidden non-unique transitions and applies it to confirm the virtual beta-gamma transition in 59Ni decay.

Findings

Gamma spectrum distorted at high energy end.

Virtual beta-gamma transition constitutes about 4% of total gamma intensity.

Theoretical predictions match experimental data well.

Abstract

A novel theory of radiative electron capture in second forbidden non-unique transition, is applied to reanalyze experimental data obtained previously for the decay of 59Ni. The measured gamma spectrum is shown to be distorted at the high-energy end, presenting the first direct evidence for the virtual beta-gamma transition through the excited state in 59Co. The complete theoretical predictions, including both the direct and the virtual decay channels, as well as the interference between them, reproduce very well the experimental spectrum. The virtual nuclear component amounts to about 4% of the total gamma intensity.