Speaker
Description
The behavior of nuclear level densities and gamma strength functions for many regions of the nuclear landscape are not well understood, especially for and not just away from stability. For example, in the Fe-Cd region, an unexpected increase in the gamma-decay probability is seen as an up-bend in the gamma strength function below ~4 MeV. This potentially has a significant influence on extracted neutron-capture rates. It is unknown how the gamma strength function behaves for neutron-rich nuclei. Nuclear level densities and gamma strength functions are critical for constraining neutron-capture rates. Rates are often crucial missing observables for models of the r and i-processes. For the i-process in particular, sensitivity studies indicate isotopes within ~3-7 mass units of stability are often critical isotopes in determining the abundance distributions produced. Currently, facilities such as the NSCL/FRIB and ANL can produce these neutron-rich isotopes. The up-bend was first observed in iron isotopes and we populated excited states via beta-decay for the neutron-rich iron nuclei including Fe-64, a candidate for the up-bend in the gamma strength function. Gamma decays within Fe-64 were recorded with the Summing Na(I) (SuN) segmented total absorption spectrometer, which allows us to simultaneously extract the level density and strength function. We will discuss the glimpse Fe-64 provides into the evolution of these properties with increasing neutron number.
