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Isospin dependent thermodynamics of fragmentation

Ad. R. Raduta·F. Gulminelli
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Abstract

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.

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Ad. R. Raduta, F. Gulminelli. 2008-06-09. Isospin dependent thermodynamics of fragmentation. https://doi.org/10.1103/physrevc.75.044605

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