Symmetry energy from nuclear multifragmentation

TL;DR

This paper investigates how to accurately determine the symmetry energy coefficient from nuclear fragmentation data, emphasizing the importance of using fragment yields at the reaction's breakup stage and the grand canonical model for reliable results.

Contribution

It demonstrates that the symmetry energy coefficient can be reliably extracted using the grand canonical model at the breakup stage, highlighting the limitations of using cold fragment yields.

Findings

Theoretical calculations agree with experimental data for $C_{sym}/T$ values.

Using fragment yields at breakup improves symmetry energy estimation.

Cold fragment yields can lead to incorrect symmetry energy conclusions.

Abstract

The ratio of symmetry energy coefficient to temperature $C_{sym}/T$ is extracted from different prescriptions using the isotopic as well as the isobaric yield distributions obtained in different projectile fragmentation reactions. It is found that the values extracted from our theoretical calculation agree with those extracted from the experimental data but they differ very much from the input value of the symmetry energy used. The best possible way to deduce the value of the symmetry energy coefficient is to use the fragment yield at the breakup stage of the reaction and it is better to use the grand canonical model for the fragmentation analysis. This is because the formulas that are used for the deduction of the symmetry energy coefficient are all derived in the framework of the grand canonical ensemble which is valid only at the break-up (equilibrium) condition. The yield of "cold" fragments either from the theoretical models or from experiments when used for extraction of the symmetry energy coefficient using these prescriptions might lead to the wrong conclusion.