Roles of system size and excitation energy in probing nuclear dissipation with giant dipole resonanceγrays

Abstract

Using the stochastic Langevin model, we calculate the evolution of postsaddle giant dipole resonance (GDR) $\ensuremath{\gamma}$-ray multiplicity (${M}_{\ensuremath{\gamma}}$) as a function of the postsaddle friction strength ($\ensuremath{\beta}$) with excitation energy for ${}^{240}$Cf, ${}^{224}$Th, and ${}^{200}$Pb systems. It is found that with raising the excitation energy the sensitivity of the postsaddle $\ensuremath{\gamma}$ emission to friction is substantially increased. We further find that ${M}_{\ensuremath{\gamma}}$ shows a greater sensitivity to $\ensuremath{\beta}$ with increasing size of the fissioning nucleus. The results suggest that on the experimental side, populating those fissioning systems with a large size and a high energy favors better determination of the postsaddle friction strength by measuring the GDR $\ensuremath{\gamma}$ multiplicity emitted in the fission process.