Article

The Isospin Dependence Of The Nuclear Equation Of State Near The Critical Point

Physical Review C (Impact Factor: 3.72). 02/2010; DOI: 10.1103/PhysRevC.81.044618
Source: arXiv

ABSTRACT We discuss experimental evidence for a nuclear phase transition driven by the different concentration of neutrons to protons. Different ratios of the neutron to proton concentrations lead to different critical points for the phase transition. This is analogous to the phase transitions occurring in 4He-3He liquid mixtures. We present experimental results which reveal the N/A (or Z/A) dependence of the phase transition and discuss possible implications of these observations in terms of the Landau Free Energy description of critical phenomena. Comment: 14 pages, 18 figures

0 Bookmarks
 · 
71 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: Thermal and isospin composition effects on the heat capacity of infinite nuclear matter are studied within the binodal coexistence region of the nuclear phase diagram. Assuming the independent conservation of both proton and neutron densities, a second-order phase transition is expected, leading to a discontinuous behavior of the heat capacity. This discontinuity is analyzed for the full range of the thermodynamical variables consistent with the equilibrium coexistence of phases. Two different effective models of the nuclear interaction are examined in the mean-field approximation: the nonrelativistic Skyrme force and the covariant QHD formulation. We found qualitative agreement between both descriptions. The discontinuity in the specific heat per particle is finite and decreases with both the density of particles and the isospin asymmetry. As a byproduct, the latent heat for isospin-symmetric matter is considered.
    Physical Review C 01/2012; 85(1). · 3.72 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Projectile fragmentation cross sections are calculated for reactions of 20Ne on the C, Al, Cu, Sn and Pb targets at 400 A MeV by using the improved quantum molecular dynamics model together with the statistical model code GEMINI. The improved quantum molecular dynamics model is applied to describe the dynamical process, and the GEMINI model is used to simulate the de-excitation process of excited primary fragments. It is found that the total cross sections increase as a function of the target mass, which is in good agreement with the experimental results and other theoretical predictions. The odd–even effect of the partial cross sections observed in experiments is well reproduced, which appears in the de-excitation process of the excited primary fragments as a result of pairing effect and is mainly formed in the grazing collisions. The results of isospin distributions demonstrate that the odd–even effect of partial cross sections mainly comes from the fragments with TZ = 0, ±0.5.
    Journal of Physics G Nuclear and Particle Physics 05/2012; 39(5). · 5.33 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: The critical phenomenon of the nuclear liquid-gas phase transition has been investigated in the reactions 64Zn+64Zn, 64Ni+64Ni and 70Zn+70Zn at beam energy of 35 MeV/nucleon. Yields of fragments arising from fragmenting quasi-projectiles (QPs) with different neutron-proton asymmetries were analyzed within the framework of the Landau free energy approach. Fits to the free energy of fragments as a function of fragment asymmetry showed three minima, indicating the system to be in a regime of a first-order phase transition. The QP temperature estimates were extracted from the analysis of N=Z fragment data. Additionally, we make use of a recent method based on quantum fluctuations of fermions to derive temperatures and densities of selected QPs. Critical scaling of these observables is found for systems which differ in neutron to proton asymmetry. The derived critical exponent β = 0.35 ± 0.01, belongs to the liquid-gas universality class.
    Journal of Physics Conference Series 03/2013; 420(1):2110-.

Full-text (2 Sources)

Download
34 Downloads
Available from
May 22, 2014