Investigation of Low-Density Symmetry Energy via Nucleon and Fragment Observables

TL;DR

This paper uses stochastic transport simulations to identify new observables in nuclear collisions that are sensitive to the symmetry energy at sub-normal densities, enhancing understanding of nuclear matter properties.

Contribution

It introduces novel observables, such as the isospin imbalance ratio and IMF asymmetry ratio, for probing low-density symmetry energy in nuclear reactions.

Findings

Isospin imbalance ratio correlates with isospin diffusion.

IMF to residue asymmetry ratio indicates isospin migration.

New observables improve sensitivity to symmetry energy below normal density.

Abstract

With stochastic transport simulations we study in detail central and peripheral collisions at Fermi energies and suggest new observables, sensitive to the symmetry energy below normal density. As such we identify on one hand the isospin imbalance ratio, i.e. the relative amount of isospin equilibration in binary, peripheral reactions of nuclei with different isospin, as a function of the energy loss, which is sensitive to isospin diffusion; on the other hand the isospin asymmetry of an intermediate mass fragment (IMF) in symmetric collisions in ternary reactions, or more particularly, the ratio of the IMF to the residue asymmetry, which is sensitive to isospin migration.