Isospin Diffusion in ${}^{58}$Ni-Induced Reactions at Intermediate Energies

Abstract

Isospin diffusion is probed as a function of the dissipated energy by studying two systems ${}^{58}$Ni+${}^{58}$Ni and ${}^{58}$Ni+${}^{197}$Au, over the incident energy range 52-74\AM. Experimental data are compared with the results of a microscopic transport model with two different parameterizations of the symmetry energy term. A better overall agreement between data and simulations is obtained when using a symmetry term with a potential part linearly increasing with nuclear density. The isospin equilibration time at 52 \AM{} is estimated to 130$\pm$10 fm/$c$.