English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

A strong enhancement at low $\gamma$-ray energies has recently beendiscovered in the $\gamma$-ray strength function of $^{56,57}$Fe. In this work,we have for the first time obtained theoretical $\gamma$ decay spectra forstates up to $\approx 8$ MeV in excitation for $^{56,57}$Fe. We find large$B(M1)$ values for low $\gamma$-ray energies that provide an explanation forthe experimental observations. The role of mixed $E2$ transitions for thelow-energy enhancement is addressed theoretically for the first time, and it isfound that they contribute a rather small fraction. Our calculations clearlyshow that the high-$\ell$ ($=f$) diagonal terms are most important for thestrong low-energy $M1$ transitions. As such types of $0\hbar\omega$ transitionsare expected for all nuclei, our results indicate that a low-energy $M1$enhancement should be present throughout the nuclear chart. This could havefar-reaching consequences for our understanding of the $M1$ strength functionat high excitation energies, with profound implications for astrophysicalreaction rates.

Large low-energy $M1$ strength for $^{56,57}$Fe within the nuclear shell model