三轴形变核^(131)Ba中的奇异集体激发模式  

Exotic collective excitation patterns in triaxially deformed^(131)Ba

作　　者：韦锐 周厚兵[1,2] 王思成 丁兵[3,4] 强赟华 贾晨旭[3,4] 陈红星 郭松[3,4] C.M.Petrache D.Mengoni A.Astier E.Dupont[5] 吕冰锋 D.Bazzacco A.Boso A.Goasduff F.Recchia D.Testov F.Galtarossa G.Jaworski D.R.Napoli S.Riccetto M.Siciliano J.J.Valiente-Dobon C.Andreoiu F.H.Garcia K.Ortner K.Whitmore A.Ataç-Nyberg T.Bäck B.Cederwall E.A.Lawrie I.Kuti D.Sohler T.Marchlewski J.Srebrny A.Tucholski Wei Rui;Zhou Hou-Bing;Wang Si-Cheng;Ding Bing;Qiang Yun-Hua;Jia Chen-Xu;Chen Hong-Xing;Guo Song;C.M.Petrache;D.Mengoni;A.Astier;E.Dupont;Lv Bing-Feng;D.Bazzacco;A.Boso;A.Goasduff;F.Recchia;D.Testov;F.Galtarossa;G.Jaworski;D.R.Napoli;S.Riccetto;M.Siciliano;J.J.Valiente-Dobon;C.Andreoiu;F.H.Garcia;K.Ortner;K.Whitmore;A.Ataç-Nyberg;T.Bäck;B.Cederwall;E.A.Lawrie;I.Kuti;D.Sohler;T.Marchlewski;J.Srebrny;A.Tucholski(College of Physical Science and Technology,Guangxi Normal University,Guilin 541004,China;Guangxi Key Laboratory of Nuclear Physics and Technology,Guilin 541004,China;Institute of Modern Physics,Chinese Academy of Sciences,Lanzhou 730000,China;University of Chinese Academy of Sciences,Beijing 100049,China;University Paris-Saclay,CNRS/IN2P3,IJCLab,Orsay 91405,France;Dipartimento di Fisica e Astronomia,Universitédegli Studi di Padova,Padova I-35131,Italy;NFN,Sezione di Padova,I-35131 Padova,Italy;INFN,Laboratori Nazionali di Legnaro,Legnaro(Padova),I-35020,Italy;Dipartimento di Fisica e Scienze della Terra,Universitédi Ferrara,Ferrara,Italy;Department of Chemistry,Simon Fraser University,Burnaby,BC V5A 1S6,Canada;KTH Department of Physics,Stockholm S-10691,Sweden;iThemba LABS,National Research Foundation,PO Box 722,Somerset West 7123,South Africa;Department of Physics&Astronomy,University of the Western Cape,P/B X17,Bellville ZA-7535,South Africa;HUN-REN Institute of Nuclear Research,ATOMKI,Debrecen 4001,Hungary;University of Warsaw,Heavy Ion Laboratory,Pasteura 5a,Warsaw 02-093,Poland)

机构地区：[1]广西师范大学物理科学与技术学院,桂林541004 [2]广西核物理与核技术重点实验室,桂林541004 [3]中国科学院近代物理研究所,兰州730000 [4]中国科学院大学,北京100049 [5]巴黎萨克雷大学,CNRS/IN2P3,IJCLab,奥赛91405 [6]帕多瓦大学物理和天文学系,帕多瓦I-35131 [7]意大利国家核物理研究所帕多瓦分部,帕多瓦I-35131 [8]意大利国家核物理研究所莱尼亚罗国家实验室,莱尼亚罗(帕多瓦)I-35020 [9]费拉拉大学理学与自然科学院,费拉拉 [10]西蒙菲莎大学化学系,本拿比BC V5A 1S6 [11]皇家理工学院物理系,斯德哥摩尔S-10691 [12]国家研究基金会iThemba加速器科学实验室,西萨默塞特7123 [13]西开普大学物理与天文系,贝尔维尔ZA-7535 [14]HUN-REN原子核研究所,德布勒森4001 [15]华沙巴斯德拉大学重离子实验室,华沙02-093

出　　处：《物理学报》2024年第11期89-100,共12页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:12365016);广西自然科学基金(批准号:2023GXNSFAA026016)资助的课题。

摘　　要：利用意大利Legnaro实验室串列静电加速器提供的65 MeV^(13)C束流与122Sn靶的熔合蒸发反应布居了^(131)Ba的高自旋态,并搭建了新的能级纲图.新的能级纲图由15条转动带组成,包括三对手征双重带,其中两对正宇称手征带为赝自旋-手征四重带.正负宇称手征带通过一系列增强的E1跃迁连接,表明它们之间存在八极关联.在低自旋区域搭建了一条新的转动带,通过一系列γ跃迁向νh1_(1/2)晕带退激.这种能级结构与摇摆带相似,但基于现有的实验证据还难以将它确认为摇摆带,不能排除其他集体激发机制,如γ振动的影响.In the last two decades,several unique phenomena in triaxially deformed nuclei,such as chiral doublet bands and wobbling motion have been revealed.Up to now,there are still many open questions which require further experimental and theoretical studies.To explore the collective motion in ^(131)Ba,an experiment was performed using the XTU Tandem accelerator in the Legnaro laboratory,Italy.High-spin states of ^(131)Ba have been populated via the heavy-ion fusion-evaporation ^(122)Sn(^(13)C,4n)reaction.γ-rays,charged particles and neutrons emitted from the residues were detected by the GALILEO array,EUCLIDES silicon ball,and the Neutron Wall,respectively.A total of 1.2×10^(9) triple-or higher-fold events were collected by the GALILEO data acquisition system.Theγ-γ-γcoincidence events were sorted into a three-dimensional histogram(cube)and the analysis was carried out with the RADWARE and GASPWARE software packages.Through analysis of the coincidences betweenγ-rays,the most comprehensive level schemes of~(131)Ba to date was deduced from the present work.The extended level-scheme consists of 15 rotational bands,and newly observed transitions are marked in red.Three nearly degenerate pairs of doublet bands(Band 3–8)are identified in^(131)Ba.Two pairs of chiral doublets(Band 3–6)with configurationπh_(11/2(g7/2,d5/2))■νh_(11/2)are interpreted as a set of pseudospin-chiral quartet bands.The quartet bands are fed by another pair of chiral doublet bands(Band 7–8)built on aπh_(11/2)^(2)■νh11/2 configuration via a series of enhanced E1 transitions.We extracted the energy displacementδE and the B(E1)/B(E2)branching ratios between the positive-parity band 3 and the negative-parity band 7 in~(131)Ba and in comparison with those in 124Ba,224Th,133Ce and 135Nd.The energy displacementδE and the B(E1)/B(E2)branching ratios in~(131)Ba are comparable with those in 124Ba but deviate appreciably from those in~(224)Th which has been reported to have stable octupole deformation.The results indicate the existence of oc

关 键 词：高自旋态 手征带 赝自旋 八极关联 摇摆运动 

分 类 号：O57[理学—粒子物理与原子核物理]