2025/06/21 by Guo, Yuan-Qing, Zhang, Ya-Peng, Feng, Zhao-Qing
#FOS: Physical sciences #Nuclear Theory (nucl-th)
paper · doi:10.48550/arxiv.2506.17571
Within the framework of Lanzhou quantum molecular dynamics transport model, the correlation of initial deformation and isospin diffusion is systematically investigated in collisions of 238U + 238U. The impacts of the collision centrality, symmetry energy and initial configuration on the collective flows, neutron/proton and π-/π+ 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 ρ0 (the normal nuclear density ρ0=0.165 fm-3) formed in the 238U + 238U 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 π-/π+ ratios in the density regime of 1.2≤ ρ/ρ0≤1.8 are enhanced by the soft symmetry energy with the slope parameter of L=42 MeV.