^(235,237)Np高自旋态的理论研究  

Theoretical Investigation of the High-spin States in ^(235,237)Np

作　　者：陈思怡 刘硕一 张振华[1] CHEN Siyi;LIU Shuoyi;ZHANG Zhenhua(Mathematics and Physics Department,North China Electric Power University,Beijing 102206,China)

机构地区：[1]华北电力大学数理学院,北京102206

出　　处：《原子核物理评论》2022年第4期413-420,共8页Nuclear Physics Review

基　　金：国家自然科学基金资助项目(11875027,11975096)。

摘　　要：锕系核的转动性质对于揭示A≈250质量区原子核的顺排机制、对关联性质、能级结构等十分重要,研究这些核的高自旋结构一方面可以对现有的理论模型进行检验,另一方面有助于深入认识超重核。本工作.采用基于推转壳模型的粒子数守恒方法研究了实验上观测到的^(235)Np和^(237)Np中转动带的性质,计算得到的转动惯量、角动量顺排等与实验符合。首先,通过描述转动谱的ab公式确定了235Np中观测到的转动带的带头自旋。随后,通过对比理论与实验上的转动惯量,确定了其组态为π5/2-[523]。此外,也讨论了高阶形变ε6对中子j_(15/2)顺排的作用,探索了在计算中出现而在实验上未观测到中子j_(15/2)顺排的原因,从而解释了^(235,237)Np的转动带中产生.上弯的机制。最后,还讨论了237INp的转动带π5/2-[523]中出现旋称劈裂的原因,发现可能是由于这个转动带的两个旋称分支。上弯以后高阶形变ε6不同所导致的。The rotational properties of the actinides are quite important for revealing the alignment mechanism,pairing correl-ations,level structure etc.,of the nuclei in A≈250 mass region.On the one hand,investigation of the high-spin structures of these nuclei can provide benchmark for testing various theoretical models.On the other hand,it can help us to get more in-formation about the superheavy nuclei.In this work,the particle-number conserving method based on the cranked shell model is adopted to investigate the rotational bands observed in ^(235)Np and ^(237)Np.The moments of inertia,alignments etc.,are repro-duced by the calculations.Firstly,the ab formula which is used to investigate the rotational spectra,is adopted to determine the bandhead spin of the rotational bands observed in ^(235)Np.Secondly,by comparing the experimental and calculated mo-ments of inertia,the configuration for this signature partner band is assigned asπ5/2[523].Moreover,the influence of higher-order deformation ε6 on the alignments of neutron j_(15/2) is discussed.The appearance of the neutron j_(15/2) alignment in the cal-culations,which is non-existent in experiment,is explored.The upbending mechanism in 235.237Np is investigated.Finally,the possible reason for the signature splitting of the rotational bandπ5/2[523]in ^(237)Np is explored,which may due to the differ-ent higher-order deformationε6 in these two signature branches of this band after upbending.

关 键 词：锕系核 转动谱 推转壳模型 粒子数守恒方法 

分 类 号：O571.53[理学—粒子物理与原子核物理]