摘要:
在Skyrme-Hartree-Fock-Bogoliubov (SHFB)理论框架下,利用SkOP1,SkOP2,SKC和SKD 4套新的Skyrme相互作用参数系统地研究了Ca,Ni,Sn和Pb同位素链上原子核的结合能、电荷半径等基态性质,并重点讨论了丰中子Ca核的新中子幻数以及Pb的同位素位移现象.通过与实验数据和SLy5相互作用参数的结果对比,发现这4套相互作用参数都能很好地再现结合能的实验数据,其预言精度比SLy5要高.对于丰中子Ca核,只有SKC和SKD相互作用参数能够再现N=-28处的壳效应,而对于实验上发现的新幻数Ⅳ=32和34,所有的相互作用参数均不能再现这一结果.对于电荷半径,发现所有的相互作用参数均不能很好地预言Ca同位素链电荷半径的演化规律以及Pb的同位素位移现象.另外,还将这些相互作用参数推广至远离β稳定线原子核的单粒子能级结构研究,发现其不适用于描述其随同位旋的演化行为.因此,为了更好地描述远离β稳定线原子核的宏观性质及单粒子能级,建议在拟合Skyrme相互作用参数时,除自旋—轨道耦合项包括合理的同位旋依赖外,还要考虑张量力成分.
Abstract:
The nuclear ground state properties of Ca,Ni,Sn and Pb isotopes,such as the binding energies,the charge radii,are studied systematically by 4 sets of new Skyrme parametrizations SKC,SKD,SkOP1 and SkOP2 in the framework of the Skyrme-Hartree-Fock-Bogoliubov (SHFB) method.The new magic numbers of neutronrich Ca isotopes and the isotopic shift of Pb isotopes are discussed emphatically.By the comparisons between the calculations and the experimental data and results from the SLy5 interaction parametrization,it is found that the experimental binding energies can be reproduced accurately by all parametrizations.The calculated accuracies of SKC,SKD SkOP1 and SkOP2 parametrizations are higher than the ones of SLy5 parametrization.For the neutron-rich Ca nuclei,the shell effect of N=28 can be reproduced by the SKC and SKD parametrizations,but the magic numbers at N=32 and 34 are not found by the calculations of all the parametrizations.For the charge radii,the experimental evolution tendency of Ca isotopes and isotopic shift of Pb isotopes can not be reproduced by all the parametrizations.In addition,all Skyrme parametrizations are extended to study the structure of the nuclei far from the β stability line,it is shown that the single-particle energy evolutions with the isospin are not suitable for being studied by these parametrizations.Thus the tensor force component should be considered besides the isospin dependence in spin-orbit coupling term when the Skyrme interaction parametrizations are fitted.
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