Effects of symmetry energy in $^{132}\rm {Sn}+^{124}\rm {Sn}$ reaction at 300 MeV/nucleon

TL;DR

This study uses an updated transport model to analyze how symmetry energy influences neutron/proton and pion ratios in a specific nuclear reaction at 300 MeV/nucleon, revealing their sensitivity to different density regions.

Contribution

It demonstrates that the n/p and $\pi^{-}/\pi^{+}$ ratios can probe symmetry energy at specific nuclear densities, with potential to explore higher densities through kinematic restrictions.

Findings

n/p ratio probes symmetry energy at 1-1.5 times saturation density

$\pi^{-}/\pi^{+}$ ratio can probe above 1.5 times saturation density with restrictions

symmetry energy effects are significant in central $^{132} m {Sn}+^{124} m {Sn}$ reactions

Abstract

Based on the recently updated Isospin-dependent Boltzmann-Uehling-Uhlenbeck (IBUU) transport model, we studied the effects of symmetry energy on the neutron to proton n/p ratio and the $\pi^{-}/\pi^{+}$ ratio in central $^{132}\rm {Sn}+^{124}\rm {Sn}$ reaction at 300 MeV/nucleon. It is found that the n/p ratio and the $\pi^{-}/\pi^{+}$ ratio in central $^{132}\rm {Sn}+^{124}\rm {Sn}$ reaction at 300 MeV/nucleon mainly probe the symmetry energy in the density region 1-1.5 times saturation density. However, the $\pi^{-}/\pi^{+}$ ratio may be able to probe the density-dependent symmetry energy above 1.5 times saturation density by making some kinematic restrictions such as the azimuthal angle and kinetic energy cuts of emitting pions.