Giant dipole resonance width and the universality of a fluctuation model including critical temperature

Abstract

The universality of the critical-temperature-included fluctuation model (CTFM) in explaining the evolution of the giant dipole resonance (GDR) width as a function of angular momentum is examined in light of recent experimental data on ${}^{144}$Sm and ${}^{152}$Gd. We compare both data sets with the phenomenological formula based on the CTFM and the thermal shape fluctuation model (pTSFM). The CTFM describes both data sets reasonably well using the actual ground state GDR width (${\ensuremath{\Gamma}}_{0}$), whereas the pTSFM describes the ${}^{144}$Sm data well but is unable to explain the ${}^{152}$Gd data using a single value of ${\ensuremath{\Gamma}}_{0}$ for the two excitation energies. These interesting results clearly indicate that the phenomenological CTFM can be used universally to describe the evolution of the GDR width with both angular momentum and temperature in the entire mass region. Moreover, it should provide insights into the modification of the TSFM.