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.
Categories: nucl-th nucl-ex