^(130)Ba中的集体运动  

Collective Motion in ^(130)Ba

作　　者：郭松[1,2] 周厚兵 Petrache CM[5] 强赟华 GUO Song;ZHOU Houbing;Petrache CM;QIANG Yunhua(Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China;University of Chinese Academy of Sciences,Beijing 100049,China;Department of Physics,Guangxi Normal University,Guilin 541004,Guangxi,China;Guangxi Key Laboratory of Nuclear Physics and Technology,Guangxi Normal University,Guilin 541004,Guangxi,China;Centre de Sciences Nucléaires et Sciences de la Matière,CNRS/IN2P3,UniversitéParis-Saclay,Bât.104-108,91405Orsay,France)

机构地区：[1]中国科学院近代物理研究所,兰州730000 [2]中国科学院大学,北京100049 [3]广西师范大学物理科学与技术学院,广西桂林541004 [4]广西核物理与核技术重点实验室,广西桂林541004 [5]巴黎-萨克雷大学原子核与材料科学中心,法国奥赛91405

出　　处：《原子核物理评论》2020年第3期530-535,共6页Nuclear Physics Review

基　　金：国家自然科学基金资助项目(11965003,11505035,11675266);广西自然科学基金资助项目(2017GXNSFAA198160,2017GXNSFGA198001);广西高等学校高水平创新团队及卓越学者计划资助。

摘　　要：为探索原子核中的集体运动,一项在意大利Legnaro实验室XTU串列加速器上开展的在束γ谱学实验研究大幅拓展了^(130)Ba的能级结构。实验以能量为65 MeV的^(13)C束流轰击^(120)Sn薄靶,布居^(130)Ba的激发态。从激发态退激的γ射线由GALILEO阵列探测,而与之关联的蒸发粒子由带电粒子阵列EUCLIDES和中子墙NWALL探测。分析符合数据鉴别了一系列新的转动带,其中一部分布居9.4 ms同核异能态。结合已知的电四极矩和磁矩信息,提取了该同核异能态的g因子。分析多条转动带,发现^(130)Ba可能处于长椭形变,也可能处于扁椭形变,而其集体转动方向可能沿主轴,也可能沿主轴以外的倾斜方向。这是首次在^(130)核区发现沿倾斜方向的集体转动。理论分析建议将部分新发现的结构解释为基于二准粒子组态的摇摆运动,这是实验上在偶偶核中观测到的首例基于两准粒子组态的摇摆带结构。An in-beam γ spectroscopic study,based on the XTU Tandem accelerator of the Laboratori Nazionali di Legnaro in Italy,has been performed to explore the collective motion in ^(130) Ba.A significantly extended level scheme of ^(130) Ba has been built in the present work.High-spin states of ^(130) Ba were populated via the 122 Sn(13 C,5 n)reaction at a beam energy of 65 MeV.The γ rays were detected by the GALILEO spectrometer,while the neutrons and charged particles were detected by the Neutron Wall array and the EUCLIDES silicon apparatus,respectively.A series of new rotational bands in ^(130) Ba have been identified,among which there is a new structure populating to the previously known 9.4 ms isomer.With the help of previously reported intrinsic quadrupole moment and magnetic moment,we extracted precise value of the g factors of this isomer.According to the band structure analysis,the coexistence of prolate and oblate shapes has been observed in ^(130) Ba,while the orientation of collective rotation can be either along or away from the principal axes.It is the first time to identify a tilted band in the A=^(130) mass region.Theoretical analysis suggests that a new band can be interpreted as the wobbling motion built on two-quasiparticle configuration,which is the first wobbling band observed in an even-even nucleus.

关 键 词：集体运动 顺排 摇摆运动 同核异能态 

分 类 号：O571.5[理学—粒子物理与原子核物理]