化学不稳定性和同位素分布的同位旋效应

CHEMICAL INSTABILITY AND ISOSPIN EFFECTS IN ISOTOPIC DISTRIBUTIONS

采用同位旋相关的量子分子动力学模型 ,研究了在轰击能量为 40MeV u和 10 0MeV u时 ,1 1 2 Sn +1 1 2 Sn和1 2 4Sn +1 2 4Sn反应产物的同位素分布 .发现在 40MeV u时 ,同位素分布与入射体系的同位旋密切相关 ;而在 10 0MeV u时 ,对这两种不同同位旋体系给出几乎相同的同位素分布 .

Within the framework of isospin-dependent quantum molecular dynamics model,isotopic distributions in the reactions of Sn-112 + Sn-112 and Sn-124 + Sn-124 at 40 and 100 MeV/u are investigated. It is found that the isotopic distribution has a significant isospin effect at 40 MeV/u,but the isospin effect disppears at 100 MeV/u. By investigating mechanical and chemical instabilities at different energies,we find that the energy dependence of isospin effects on isotopic distributions results from the competition between mechanical instabilities and chemical instabilities at different energies.