Isotopic dependence of the fragments' internal temperatures observed in multifragment emission

Abstract

The internal temperatures of fragments produced by an excited nuclear source are investigated using the microcanonical version of the Statistical Multifragmentation Model, with discrete energy. We focus on the fragments' properties at the breakup stage, before they have time to deexcite by particle emission. Since the adopted model provides the excitation energy distribution of these primordial fragments, it allows one to calculate the temperatures of different isotope families and infer on the sensitivity to their isospin composition. It is found that, due to the functional form of the nuclear density of states and the excitation energy distribution of the fragments, proton rich isotopes are hotter than neutron rich ones. This property has been taken to be an indication of earlier emission of the former from a source that cools down as it expands and emits fragments. Although this scenario is incompatible with the prompt breakup of a thermally equilibrated source, our results reveal that the latter framework also provides the same qualitative features just mentioned. Therefore they suggest that this property cannot be taken as evidence for non-equilibrium emission. We also found that this sensitivity to the isotopic composition of the fragments depends on the isospin composition of the source, and that it is weakened as the excitation energy of the source increases.

5 pages, 3 figures

References in corpus (8)

• Nuclear multifragmentation and phase transition for hot nuclei
• Asymmetry Dependence of the Nuclear Caloric Curve
• A novel determination of density, temperature and symmetry energy for nuclear multi-fragmentation through primary fragment yield reconstruction
• Experimental reconstruction of primary hot isotopes and characteristic properties of the fragmenting source in the heavy ion reactions near the Fermi energy
• Reconstructed primary fragments and symmetry energy, temperature and density of the fragmenting source in ${}^{64}$Zn + ${}^{112}$Sn at 40 MeV/nucleon
• Cooling Dynamics in Multi-fragmentation processes
• Fragments' internal and kinetic temperatures in the framework of a Nuclear Statistical Multifragmentation Model
• Dynamical and many-body correlation effects in the kinetic energy spectra of isotopes produced in nuclear multifragmentation