首次建立缺中子核素^(209)Fr的分支比很弱的(EC+β^+)衰变纲图  

First Study of Weak(EC+β +)Decay Branch for the Neutron-Deficient Isotoep 209 Fr

作　　者：谢元祥[1] 徐树威[1] 郭应祥[1] 马瑞昌[1] 葛元秀[1] 李占奎[1] 王春芳[1] 郭斌[1] 邢建萍[1] 张天梅[1] 朱少飞[1] 徐望 

机构地区：[1]中国科学院近代物理研究所

出　　处：《高能物理与核物理》1997年第4期289-291,共3页High Energy Physics and Nuclear Physics

基　　金：中国科学院和国家自然科学基金

摘　　要：用１６Ｏ束轰击１９７Ａｕ靶，通过熔合蒸发４ｎ反应产生了２０９Ｆｒ，借助于氦喷嘴带传输系统对其衰变性质进行了研究．由－ｔ，Ｘ－－ｔ，－－ｔ符合及－延迟符合测量得到的结果，首次建立了２０９Ｆｒ的（ＥＣ＋β＋）衰变纲图．它包含了２０条射线．２０９Ｒｎ的５个低位态的成员可以用［（２１０Ｒｎ２＋）（νｆ５／２）－１］多重态结构来解释．实验估计２０９Ｆｒ（ＥＣ＋β＋）衰变的分支比为（３．０±１．５）％．Fr has been produced by irradiation of 197 Au with 16 O from SFC accelarator uia the fusion evaporation 4n channel.The (EC+β +)decay of 209 Fr has been studied by a He jet tape transport system.The decay scheme is proposed for the first time based on -t,X--t,--t coincidece and - delay coincidence measurements,which takes account of 20 observed  ray.Five members of low lying states in 209 Rn can be explained by the multiplet [( 210 Rn 2 +)(νf 5/2 ) -1 ].The branching ratio for (EC+β +)decay of 209 Fr has been estimated experimentally to be (3.0±1.5)%.

关 键 词：衰变纲图 分支比 多重态结构 钫209 

分 类 号：O614.116[理学—无机化学] O571.3[理学—化学]