Density reorganization in hot nuclei

Abstract

The density profile of a hot nuclear system produced in intermediate-energy heavy ion collisions is studied in a microcanonical formulation with a momentum and density dependent finite range interaction. The caloric curve and density evolution with excitation are calculated for a number of systems for the equilibrium mononuclear configuration; they compare favorably with the recent experimental data. The studied density fluctuations are seen to build up rapidly beyond an excitation energy of ∼8 MeV/u indicating the instability of the system toward nuclear disassembly. Explicit introduction of deformation in the expansion path of the heated nucleus, however, shows that the system might fragment even earlier. We also explore the effects of the nuclear equation of state and of the mass and isospin asymmetry on the nuclear equilibrium configuration and the relevant experimental observables.

Temperature dependence of the symmetry energy of finite nuclei

“…6 for A = 56. The chosen nuclear pairs (Z 1 , Z 2 ) are (24,26), (24,28), and (26,28). The upper panel displays the temperature dependence of e sym and the lower panel shows the same for f sym .…”

“…The details for obtaining the density in this method for the SkM * force are given in Ref. [15]; for the SBM interaction, they have also been presented earlier [14,24]. However, for completeness, we present the salient features below.…”

Density dependence of the symmetry free energy of hot nuclei

“…At the same excitation, both C E and C F are larger for the stiffer EOS. This is understood from the fact that at the same excitation, the equilibrium configuration is more compact for the stiffer EOS [29]. As a whole, the symmetry coefficients are found to be not too sensitive to the choice of the EOS we have made.…”

“…8 of the symmetry coefficient C F for the more asymmetric nucleus 150 Cs can be traced to the fact that isobars with higher asymmetry have effectively softer EOS [29]. It is seen that the results for the symmetry coefficients for the pair 197 Au and 150 Sm are practically indistinguishable.…”

“…In addition to its simplicity, there is no a priori justification for this choice; however, it has been shown that with a harmonic oscillator potential, at relatively small temperatures, the scaled density profiles and those generated self-consistently in a constrained Thomas-Fermi [25] procedure are equivalent [29]. One further needs to account properly for the effect of collectivity, as the coupling of the single-particle motion with the collective degrees of freedom [30] is not included in the FTTF procedure.…”