Exploring the neutron-star matter properties via the deformed nuclear reactions

TL;DR

This study uses the Lanzhou quantum molecular dynamics model to explore how initial deformation affects isospin diffusion and other observables in uranium-238 collisions, providing insights into neutron-star matter properties at sub-saturation densities.

Contribution

It systematically investigates the effects of initial deformation, collision centrality, and symmetry energy on reaction dynamics and neutron-star matter formation in uranium-238 collisions.

Findings

Broader neutron-rich regions form in body-body collisions.

Neutron-star matter may form at 0.2-0.5 times nuclear saturation density.

Symmetry energy influences neutron/proton and pion ratios.

Abstract

Within the framework of Lanzhou quantum molecular dynamics transport model, the correlation of initial deformation and isospin diffusion is systematically investigated in collisions of $^{238}$U + $^{238}$U. The impacts of the collision centrality, symmetry energy and initial configuration on the collective flows, neutron/proton and $\pi^{-}/\pi^{+}$ ratios have been systematically investigated. It is found that the broader neutron-rich region is formed in the body-body collisions in comparison with the ones in the tip-tip collisions. The neutron-star matter might be created in the density region of 0.2-0.5 $\rho_{0}$ (the normal nuclear density $\rho_{0}$=0.165 fm$^{-3}$) formed in the $^{238}$U + $^{238}$U reaction at the incident energy of 500 MeV/nucleon. The elliptic flows of protons are related to the incident energy, collision centrality, symmetry energy and collision orientation. The hard symmetry energy enables the larger free neutron/proton ratio at the beam energy of 500 MeV/nucleon. However, the neutron/proton and $\pi^{-}/\pi^{+}$ ratios in the density regime of $1.2\leq \rho/\rho_{0}\leq1.8$ are enhanced by the soft symmetry energy with the slope parameter of L=42 MeV.