Normal or abnormal isospin-fractionation as a qualitative probe of nuclear symmetry energy at supradensities

TL;DR

This paper investigates how the behavior of isospin-fractionation in energetic nucleons can qualitatively indicate the nature of nuclear symmetry energy at supradensities, using transport models.

Contribution

It introduces a qualitative method to probe supradensity nuclear symmetry energy through isospin-fractionation patterns of energetic nucleons.

Findings

Positive symmetry potential leads to higher neutron/proton ratios in free nucleons.

Negative symmetry potential results in lower neutron/proton ratios in free nucleons.

Normal or abnormal isospin-fractionation serves as a qualitative indicator of symmetry energy behavior.

Abstract

Within two different frameworks of isospin-dependent transport model, effect of nuclear symmetry energy at supradensities on the isospin-fractionation (IsoF) was investigated. With positive/negative symmetry potential at supradensities (i.e., values of symmetry energy increase/decrease with density above saturation density), for energetic nucleons, the value of neutron to proton ratio of free nucleons is larger/smaller than that of bound nucleon fragments. Compared with extensively studied quantitative observables of nuclear symmetry energy, the normal or abnormal isospin-fractionation of energetic nucleons can be a qualitative probe of nuclear symmetry energy at supradensities.