偶偶Ra同位素的八极形变研究

Octupole deformation in even-even Ra isotopes

用反射不对称的相对论平均场理论(RAS-RMF)对偶偶Ra同位素的八极形变进行了系统研究,并与实验数据和有限力程小液滴模型(FRDM)结果进行了比较.结果表明:RAS-RMF理论很好地描述了Ra同位素的基态性质,计算的结合能、双中子分离能和形变与实验数据和FRDM一致.RAS-RMF理论获得的中子、质子密度分布清晰地展现出偶偶Ra同位素由球形逐渐转变为八极形变,到四极形变的过程,与实验观察的八极形变不稳定现象一致.

The octupole deformation of even-even Raisotopes has been investigated systematically by the reflection asymmetric relativistic mean field（RAS-RMF） theory.The results are compared with the experimental data together with the results from FRDM.It is shown that RAS-RMF theory gives a good description for Ra isotopes.The calculated binding energy,two neutron separation energy and deformation agree with the experimental data well.In particular,RAS-RMF theory provides the neutron and proton densities which show clearly the shape evolution of these nuclei from nearly spherical to well-developed octupole and finally back to quadrupole deformation shapes.This is in accordance with experimental observation.