Gamma-widths, lifetimes and fluctuations in the nuclear quasi-continuum

Abstract

Statistical ${\hat{I}}^3$-decay from highly excited states is determined by the nuclear level density (NLD) and the ${\hat{I}}^3$-ray strength function (${\hat{I}}^3$SF). These average quantities have been measured for several nuclei using the Oslo method. For the first time, we exploit the NLD and ${\hat{I}}^3$SF to evaluate the ${\hat{I}}^3$-width in the energy region below the neutron binding energy, often called the quasi-continuum region. The lifetimes of states in the quasi-continuum are important benchmarks for a theoretical description of nuclear structure and dynamics at high temperature. The lifetimes may also have impact on reaction rates for the rapid neutron-capture process, now demonstrated to take place in neutron star mergers.

CGS16, Shanghai 2017, Proceedings, 5 pages, 3 figures