The Nuclear Matter Symmetry Energy at $0.03\le \ddot{I}/\ddot{I}{}_0\le 0.2$

Abstract

Measurements of the density dependence of the free symmetry energy in low density clustered matter have been extended using the NIMROD multi-detector at Texas A&M University. Thermal coalescence models were employed to extract densities, $\ddot{I}$, and temperatures, $T$, for evolving systems formed in collisions of 47 $A$ MeV ${}^{40}$Ar + ${}^{112}$Sn,${}^{124}$Sn and ${}^{64}$Zn + ${}^{112}$Sn, ${}^{124}$Sn. Densities of $0.03\le \ddot{I}/\ddot{I}{}_0\le 0.2$ and temperatures in the range 5 to 10 MeV have been sampled. The free symmetry energy coefficients are found to be in good agreement with values calculated using a quantum statistical model. Values of the corresponding symmetry energy coefficient are derived from the data using entropies derived from the model.

6 pages, 6 figures