^(140)Tb和^(141)Dy的β缓发质子衰变以及^(143)Dy的自旋宇称  

β-Delayed Proton Decays of ^(140)Tb and ^(141)Dy as Well as the Spin and Parity of ^(143)Dy

作　　者：徐树威[1] 谢元祥[1] 邢烨炳[1] 许甫荣[2] 刘红亮[2] 李占奎[1] 

机构地区：[1]中国科学院近代物理研究所,兰州730000 [2]北京大学技术物理系,北京100087

出　　处：《高能物理与核物理》2006年第6期526-529,共4页High Energy Physics and Nuclear Physics

基　　金：国家自然科学基金(10375078;10475002)资助~~

摘　　要：利用40Ca+106Cd融合蒸发反应产生了近质子滴线核140Tb和141Dy,配合氦喷嘴带传输系统采用“质子-γ”符合方法观测了它们的β缓发质子衰变,其中包括半衰期、质子能谱和衰变到第二代子核不同低位态的分支比．通过统计理论拟合提取了140Tb和141Dy的基态自旋宇称分别为7±和9／2±．另一方面,用Woods-Saxon Strutinsky方法计算了这两种核限制组态的势能面,由此得到140Tb和141Dy的基态自旋宇称分别为7+和9／2-．此外用同一方法还计算了143Dy的核势能面,从中看出143Dy存在有自旋宇称为1／2+的基态和一个激发能为198keV的11／2-的同质异能态．该结果与2003年Eur．Phys．J． A16:347-351中的143Dy衰变实验数据相符．^140Tb and ^141Dy were produced via fusion evaporation in the reaction ^40Ca-^106Cd. Their B-delayed proton decays were studied by means of ＂P-γ＂ coincidence in combination with a He-jet tape transport system, including half-lives, proton energy spectra, γ-transitions following the proton emissions, and the branching ratios to the low-lying states in the grand-daughter nuclei. The ground-state spins and parities of ^140Tb and ^141Dy were extracted as 7^± and 9/2^± , respectively, by fitting the experimental data with a statistical model calculation. The configuration-constrained nuclear potential energy surfaces （NPES） of ^140Tb and ^141Dy were calculated by using the Woods-Saxon Strutinsky method, which indicate the ground-state spins and parities of ^140Tb and ^141Dy to be 7^＋and 9/2^-, respectively. In addition, the configuration-constrained NPES of ^143Dy was also calculated by using the same method. From the NPES a 1/2^＋ ground state and a 11/2^- isomer with the excitation energy of 198keV were found. The calculated results are consistent with our experimental data on the decay of 14SDy reported in Eur. Phys. J., 2003, A16： 347-351.

关 键 词：Β缓发质子衰变 自旋宇称 核势能面 

分 类 号：O571.3[理学—粒子物理与原子核物理]