Transverse emission of isospin ratios as a probe of high-density symmetry energy in isotopic nuclear reactions

摘要

Transverse emission of preequilibrium nucleons, light clusters (complexparticles) and charged pions from the isotopic $^{112,124}$Sn+$^{112,124}$Snreactions at a beam energy of 400\emph{A} MeV, to extract the high-densitybehavior of nuclear symmetry energy, are investigated within an isospin andmomentum dependent transport model. Specifically, the double ratios ofneutron/proton, triton/helium-3 and $\pi^{-}/\pi^{+}$ in the squeeze-out domainare analyzed systematically, which have the advantage of reducing the influenceof the Coulomb force and less systematic errors. It is found that thetransverse momentum distribution of isospin ratios strongly depend on thestiffness of nuclear symmetry energy, which would be a nice observable toextract the high-density symmetry energy. The collision centrality and the masssplitting of neutron and proton in nuclear medium play a significant role onthe distribution structure of the ratios, but does not change the influence ofsymmetry energy on the spectrum.