原子核的中子皮厚度与非对称核物质态方程  

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

作　　者：刘敏[1] 李祝霞[1] 

机构地区：[1]中国原子能科学研究院,北京102413

出　　处：《中国科学院研究生院学报》2007年第2期167-173,共7页Journal of the Graduate School of the Chinese Academy of Sciences

基　　金：国家自然科学基金(10235030;10235020)资助

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208^Pb、112-124^Sn、48^Ca、96^Zr、18^O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α,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：αs=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．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 208^Pb, 112-124^ Sn, 48^Ca,96^Zr,18^O 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 -3 Z,we find a linear relation between the neutron skin thickness and the isospin asymmetry degree δ： △rnp=0.053 ± 1.016δ, which is in agreement with the result extracted from the measurements by antiproton annihilation method i.e. ：△rnp = （ -0.04 ±0.03） ± （1.01 ± 0.25）8. 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 αs ： L = 20 - 100MeV, Ksym = - 256 - 70MeV, αs = 30 - 35MeV. The Skyrme parameters SLy0-SLy 10, SkM^＊, SkP, SLy230a, SkMP, SKT1-3, Ski3, MSk 1-2, SII are in the above ranges.

关 键 词：非对称核物质态方程 对称能 中子皮厚度 

分 类 号：O571[理学—粒子物理与原子核物理]