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中国科学院大学学报 ›› 2007, Vol. 24 ›› Issue (2): 167-173.DOI: 10.7523/j.issn.2095-6134.2007.2.005

• 论文 • 上一篇    下一篇

原子核的中子皮厚度与非对称核物质态方程

刘 敏 李祝霞   

  1. 1. 中国原子能科学研究院 北京 102413
  • 收稿日期:1900-01-01 修回日期:1900-01-01 发布日期:2007-03-15

The neutron skin thickness and the equation of state for asymmetric nuclear matter

LIU Ming, LI Zhu-Xia   

  1. 1 China Institute of Atomic Energy, Beijing 102413
  • Received:1900-01-01 Revised:1900-01-01 Published:2007-03-15

摘要: 挑选47组常用的Skyrme参数,采用Skyrme能量密度泛函结合拓展的Thomas-Fermi展开,用约束的密度变分法,我们计算了208Pb、112~124Sn 、 48Ca 、 96Zr、18O 等丰中子核的中子皮厚度并与实验数据分析抽取的中子皮厚度比较,研究了中子皮厚度与非对称核物质态方程中同位旋相关的对称能项之间的关系。我们发现中子皮厚度随对称能系数 a s 以及对称能在饱和密度附近的斜率L、曲率Ksym的增大呈现近似的线性增大的趋势,对称能越硬的核势确定的中子皮越厚。以反质子湮灭法拟合的参考实验值作为标准,我们给出对称能系数,对称能在饱和密度附近的斜率和曲率的参考范围分别为:as = 30 ~ 35MeV ,L = 20 ~ 100MeV,Ksym = -256 ~ 70MeV。满足这个条件的Skyrme 参数有:SLy0-SLy10、SkM*、SkP、SLy230a、SkMP、SKT1-3、SkI3、MSk1-2、SII 。

关键词: 非对称核物质态方程, 对称能, 中子皮厚度

Abstract: Based on the Skyrme energy density functional and the Thomas-Fermi expressions of the kinetic energy density, we use the restricted density variational method to calculate the neutron skin thickness for 208Pb, 112~124Sn, 48Ca, 96Zr, 18O with 47 Skyrme interactions available up to now. Comparing our calculated results with the experiment data, we explore the relations between the neutron skin thickness and the symmetry energy term of the equation of state(EOS) of nuclear matter. We find that the neutron skin thickness is sensitive to the nucleon-nucleon interaction and increases with the stiffness of the symmetry energy. Our study indicates that the model independent neutron skin thickness data are especially important for providing accurate information of the density dependence of the symmetry energy of nuclear matter. By calculating the neutron skin thickness of nuclei in the range of Z = 8 ~ 120, A = 5Z/3 ~ 3Z ,we find a linear relation between the neutron skin thickness and the isospin asymmetry degree δ: , which is in agreement with the result extracted from the measurements by antiproton annihilation method i.e.: . Using the data from antiproton annihilation method, we get the ranges of the slope , curvature of the symmetry energy near the saturated density (L, Ksym )and the symmetry energy coefficient as : L = 20 ~ 100MeV,Ksym =-256 ~ 70MeV, as = 30 ~ 35MeV. The Skyrme parameters SLy0-SLy10,SkM*,SkP,SLy230a,SkMP,SKT1-3,SkI3,MSk1-2,SII are in the above ranges.

Key words: Equation of State, Asymmetry Energy, Neutron Skin Thickness

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