Isospin fluctuations in spinodal decomposition

Colonna, M.; Matera, F.

doi:10.1103/physrevc.71.064605

Cited by 20 publications

(36 citation statements)

References 37 publications

(66 reference statements)

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“…Indeed δI/I is quite lower than 1 in all cases. The effect is larger in the asy-stiff case, which is characterized by a steeper variation of the symmetry energy with the density, in agreement with previous studies [12,31]. The asymmetry δI is more sensitive to the symmetry energy parametrization (black vs. red lines) than to the introduction of pairing correlations (full vs. dashed lines).…”

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confidence: 91%

Pairing effects on spinodal decomposition of asymmetric nuclear matter

2014

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We investigate the impact of pairing correlations on the behavior of unstable asymmetric nuclear matter at low temperature. We focus on the relative role of the pairing interaction, coupling nucleons of the same type (neutrons or protons), with respect to the symmetry potential, which enhances the neutron-proton attraction, along the clusterization process driven by spinodal instabilities. It is found that, especially at the transition temperature from the normal to the superfluid phase, pairing effects may induce significant variations in the isotopic content of the clusterized matter. This analysis is potentially useful to gather information on the temperature dependence of nuclear pairing and, in general, on the properties of clusterised low-density matter, of interest also in the astrophysical context. Investigations of many-body interacting systems have always been an exciting and attractive field in different domains of physics. Indeed understanding the properties of complex systems in terms of their constituent particles and the interaction among them is a true challenge. The original (and unsolvable) quantal many-body problem, is often approached adopting the mean-field approximation, yielding a so-called effective interaction [1,2]. However, suitable extensions of mean-field models have been introduced to take explicitly into account the effects of relevant interparticle correlations. This is the case, for instance, of pairing correlations which occur, under suitable conditions, in fermionic systems [3].Many efforts are currently focused on the study of the properties of complex nuclei and infinite nuclear matter. It is well known that nucleons can form paired states, analogous to the way electrons pair in metals, yielding a superconducting phase [3]. Pairing effects on nuclear masses are widely investigated nowadays, also in connection with astrophysical applications requiring the knowledge of the mass of very neutron-rich nuclei, which play a crucial role in the r process of nucleosynthesis [4]. Moreover, the presence of neutron superfluidity in the crust and the inner part of neutron stars is considered well established in the physics of these compact stellar objects, and has a significant effect on cooling processes [5] and glitch phenomena [6,7].Complex many-body systems are also characterized by the possible occurence of different kinds of phase transitions. For nuclear matter at sub-saturation density and relatively low temperature (T 15M eV ) liquidgas phase transitions are expected to appear, driven by the unstable mean-field. Such a process is closely linked to the multifragmentation mechanism experimentally observed in nuclear reactions [8] and to the occurrence of clustering phenomena in the inner crust of neutron stars [9,10]. Owing to the two-component structure of nuclear matter, a central role in this mechanism pertains to the density behavior of the isovector part of the effective interaction and the corresponding term in the nuclear Equation of State, the symmetry energy [11,12], on wh...

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confidence: 91%

Pairing effects on spinodal decomposition of asymmetric nuclear matter

2014

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“…Understanding their origin is also important for studies on the symmetry energy [11][12][13], which can be linked to the isotopic distributions [14] if the latter are not too much perturbed by secondary decay [15,16].…”

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confidence: 99%

Reaction mechanisms and staggering in collisions

et al. 2011

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“…Here, in order to concentrate on isospin effects, we first consider that the Coulomb interaction is switched off. The use of such an idealized neutral system will additionally allow us to make connections with the expected behavior at the thermodynamic limit and to explore the link between isospin observables (isoscaling [16,22,25,26,27,28,29], isospin fluctuations [18,22,30,31,32]) and the low density finite temperature symmetry (free) energy of the equation of state. The robustness of measurements of the symmetry energy in both finite neutral systems and real nuclei under the effect of mass and charge conservation and Coulomb is finally addressed.…”

Section: Introductionmentioning

confidence: 99%

Isospin dependent thermodynamics of fragmentation

Raduta

Gulminelli

2007

Phys. Rev. C

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The thermal and phase properties of a multifragmentation model which uses clusters as degrees of freedom, are explored as a function of isospin. A good qualitative agreement is found with the phase diagram of asymmetric nuclear matter as established by different mean-field models. In particular, from the convexity properties of the nuclear entropy, we show that uncharged finite nuclei display first and second order liquid-gas-like phase transitions. Different quantities are examined to connect the thermal properties of the system to cluster observables. In particular we show that fractionation is only a loose indication of phase coexistence. A simple analytical formula is proposed and tested to evaluate the symmetry (free) energy from the widths of isotopic distributions. Assuming that one may restore the isotopic composition of break-up fragments, it is found that some selected isotopic observables can allow to quantitatively access the freeze-out symmetry energy in multifragmentation experiments.PACS numbers: 25.70.Pq Multifragment emission and correlations, 24.10.Pa Thermal and statistical models

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Isospin fluctuations in spinodal decomposition

Cited by 20 publications

References 37 publications

Pairing effects on spinodal decomposition of asymmetric nuclear matter

Pairing effects on spinodal decomposition of asymmetric nuclear matter

Reaction mechanisms and staggering in collisions

Isospin dependent thermodynamics of fragmentation

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