Magnetic character of the low-energy enhancement in $^{70}$Zn

E. K. Ronning

Published Nature (2026)

The transition of an atomic nucleus from an excited state to a state of lower energy is typically accompanied by the emission of photons. The likelihood of photon emission is a function of the photon energy and of properties of the initial and final nuclear states and is known as the photon (or γ-ray) strength function (γSF). Of the features present in the γSF, an enhancement in the low-energy region has been observed in some nuclei, but the electromagnetic nature of this enhancement remains an open question. This low-energy enhancement in the γSF significantly impacts our understanding of how elements are created in stars and the structure of the nucleus. Here we present the results from an experiment on the γSF of 70Zn that show that the enhancement in the γSF of this nucleus is of magnetic nature. This observation helps address a long-open question about γSFs in atomic nuclei and directly impacts our predictive capabilities in nuclear science.