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

¹ Department of Physics, University of Oslo, N-0316 Oslo, Norway
² Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA

^* e-mail: magne.guttormsen@fys.uio.no
^** e-mail: a.c.larsen@fys.uio.no

Published online: 16 May 2018

Abstract

Statistical γ-decay from highly excited states is determined by the nuclear level density (NLD) and the γ-ray strength function (γSF). These average quantities have been measured for several nuclei using the Oslo method. For the first time, we exploit the NLD and γSF to evaluate the γ-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.