Probing the neutron-proton asymmetry dependence of the nuclear source temperature with light charged particles

Abstract

The dependence of the nuclear temperature on the source neutron-proton ($N/Z$) asymmetry has been experimentally investigated with the light charged particles (LCPs) generated from 13 reaction systems with different $N/Z$ asymmetries, $^{64}\mathrm{Zn}$ on $^{112}\mathrm{Sn}$, and $^{70}\mathrm{Zn}$, $^{64}\mathrm{Ni}$ on $^{112,124}\mathrm{Sn}$, $^{58,64}\mathrm{Ni}$, $^{197}\mathrm{Au}$, and $^{232}\mathrm{Th}$ at 40 MeV/u. A rather weak $N/Z$ asymmetry dependence of the source temperature has been qualitatively inferred from the extracted $N/Z$ asymmetry dependence of the apparent temperature and that of the relative temperature change by the sequential decay effects with the help of the theoretical simulations. Comparing the present result with those from our previous work and other available experimental results, a weak $N/Z$ asymmetry dependence of nuclear temperature is commonly observed in different independent experiments and with different thermometers, except for the result reported by McIntosh et al. [Phys. Lett. B 719, 337 (2013)]. The origin of the difference between the conclusion of the former group and that of McIntosh et al. is addressed, using statistical multifragmentation model (SMM) simulations.