Wobbling Motion in the Even-even Nucleus  

偶偶原子核中的摇摆运动

作　　者：SUN Bowen JI Yingzhi CHEN Qibo 孙博文;纪瑛芝;陈启博(华东师范大学物理与电子科学学院,上海200241)

机构地区：[1]Department of Physics,East China Normal University,Shanghai 200241,China

出　　处：《原子核物理评论》2024年第1期200-206,共7页Nuclear Physics Review

基　　金：国家自然科学基金资助项目(12205103);华东师范大学本科生创新创业训练项目(202310269091X,202410269133S)。

摘　　要：The recent progresses on the wobbling motion are briefly introduced.So far 17 wobbling candidates have been reported in odd-A and even-even nuclei that spread over A≈100,130,160 and 190 mass regions.The two-quasiparticle configuration wobbling in ^(130)Ba and the wobbling motion in a triaxial rotor are taken as examples in this paper to show the wobbling motion in even-even nuclei.For the ^(130)Ba,the wobbling are investigated based on the combination of the covariant density functional theory(CDFT)and the particle rotor model(PRM).The CDFT provides crucial information on the configuration and deformation parameters of observed bands,serving as input for PRM calculations.The corresponding experimental energy spectra and electromagnetic transition probabilities are reproduced.An analysis of the angular momentum geometry reveals the enhanced stability of transverse wobbling of a two-quasiparticle configuration compared to a single-quasiparticle one.For the triaxial rotor,the time evolution of wobbling motion is explored through the solution of Euler equations.This investigation yields valuable insights into the evolution of orientation angles(φ and θ)and angular momentum components.Notably,the study reveals that low-energy states of a triaxial rotor predominantly exhibit wobbling motion around the intermediate axis.Moreover,an increase in excitation energy corresponds to a prolonged period of intermediate axis wobbling motion.Conversely,a contrasting trend is observed in the case of long axis wobbling,where an increase in excitation energy leads to a decrease in the wobbling period.本工作简要介绍了摇摆运动的近期研究进展。目前在质量数为100,130,160,190核区的奇A核与偶偶核中已报导了17个摇摆候选核。以^(130)Ba中的两准粒子组态摇摆及三轴转子的摇摆运动为例说明偶偶核中的摇摆运动。对于^(130)Ba,采用协变密度泛函理论(CDFT)和粒子转子模型(PRM)来进行研究。CDFT为观察到的能带的组态和变形参数提供了关键信息,并为PRM计算提供了输入量。在^(130)Ba中,理论计算再现了实验能谱和电磁跃迁概率。角动量几何的分析揭示了两准粒子组态的横向摇摆相比单准粒子组态的横向摇摆更加稳定。对于三轴转子,利用欧拉方程来研究时间演化问题,给出了方位角(φ和θ)以及角动量分量随时间的演化图像。研究表明,三轴转子的低能激发态主要展示围绕中间轴的摇摆运动。随着激发能量的增加,中间轴摇摆运动的周期延长。相反,在长轴摇摆的情况下呈现出一种截然不同的趋势,即激发能量的增加导致摇摆周期减少。

关 键 词：wobbling motion even-even nucleus two-quasiparticle time evolution 

分 类 号：O571.2[理学—粒子物理与原子核物理]