Liquid-gas phase transition in the nuclear equation of state

Abstract

A canonical ensemble model is used to describe a caloric curve of nuclear liquid-gas phase transition. Allowing a discontinuity in the freeze out density from one spinodal density to another for a given initial temperature, the nuclear liquid-gas phase transition can be described as first order. Averaging over various freeze out densities of all the possible initial temperatures for a given total reaction energy, the first order characteristics of liquid-gas phase transition is smeared out to a smooth transition. Two experiments, one at low beam energy and one at high beam energy show different caloric behaviors and are discussed.Typeset using REVT E X 1

Nuclear multifragmentation and phase transition for hot nuclei

“…However it is a good approximation for hot nuclei when one is not interested in an event-by-event analysis and only wants to calculate mean values at very high excitation energies (≥6-7 MeV/nucleon) where the number of particles associated to deexcitation is large [37,107,108,109,110] (see subsection 2.2). A second ensemble, the canonical ensemble, is used to describe a system with a fixed number of particles in contact with a heat reservoir at fixed temperature [106,134,135]. Here the total energy fluctuates from partition to partition and only the mean value of the total energy is fixed.…”

Liquid-gas phase transitions in a multicomponent nuclear system with Coulomb and surface effects

“…Inclusion of surface tension may allow for a zero pressure isobaric phase transition and may simulate the situation of an equilibrated state of multifragmentation having zero internal pressure of stable finite nuclei with non-zero gas pressure as discussed in Ref. [9]. The effect of the Coulomb interaction makes the coexistence curve smaller.…”

“…For a given A = N + Z stability is determined by Coulomb and symmetry energy effects. Since a stable finite nucleus has zero internal pressure while the gas phase having positive pressure [9], we also need to consider surface effects. In this paper we consider the effects of Coulomb interaction and surface tension by considering uniform spherical finite nuclear system.…”

Liquid-gas phase transition in strange hadronic matter

“…One is that we can apply equilibrium thermodynamics for such a small system of only few hundred constituents at the most. The other is that a thermalized uniform system is formed in heavy ion collision before the multi-fragmentation takes place [39]. Although the equilibrium analysis oversimplifies the study of the SHM, we still follow the thermodynamic approach in the reason that this can give some concrete descriptions of the phase structure of the SHM and characterize certain aspects of the evolution.…”