Abstract
A strong enhancement at low -ray energies has recently been discovered in the -ray strength function of . In this work, we have for the first time obtained theoretical decay spectra for states up to in excitation for . We find large values for low -ray energies that provide an explanation for the experimental observations. The role of mixed transitions for the low-energy enhancement is addressed theoretically for the first time, and it is found that they contribute a rather small fraction. Our calculations clearly show that the high- diagonal terms are most important for the strong low-energy transitions. As such types of transitions are expected for all nuclei, our results indicate that a low-energy enhancement should be present throughout the nuclear chart. This could have far-reaching consequences for our understanding of the strength function at high excitation energies, with profound implications for astrophysical reaction rates.
- Received 11 September 2014
DOI:https://doi.org/10.1103/PhysRevLett.113.252502
© 2014 American Physical Society