Sn同位素的能级密度和熵

Level Densities and Entropy of Sn Isotopes

能级密度在研究核物理的动力学、热力学性质中具有重要的物理意义。本文利用壳模型和截断算法计算了Sn同位素的最低10000个状态。^(116)Sn在Sn同位素中空穴数和粒子数都为8,能级最为复杂,根据^(116)Sn能级密度研究了能级密度与角动量的关系和体系的微正则熵。研究发现在偶宇称时的最低平均能级出现明显的角动量奇偶效应,用泡利不相容原理得到合理解释。进一步,又研究了Sn同位素的此性质,得到相同的结论。^(116)Sn的微规范熵在低能量段受奇宇称的波动,这与中子对的断裂有关。

Energy level density plays an important role in the study of kinetic and thermodynamic properties of nuclear physics.In this paper,shell model and the truncation algorithm are used to calculate the lowest 10000 states of Sn isotopes.The number of holes and the number of particles in the ^(116)Sn isotope of Sn is 8,and the energy level is the most complex.According to the ^(116)Sn energy level density,the relationship between energy level density and angular momentum and the microcanonical entropy of the system are studied.It is found that the lowest average energy level under even parity has an obvious odd-even effect of angular momentum,which can be reasonably explained by Pauli exclusion principle.Furthermore,the properties of different Sn isotopes are studied and a similiar conclusion is obtained.The microcanonical entropy of ^(116)Sn is fluctuated by odd parity in the low energy band,which is related to the fracture of neutron pairs.