^(133)Sm和^(149)Yb的β缓发质子衰变  

β-Delayed Proton Decays of ^(133)Sm and ^(149)Yb

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

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,北京100871

出　　处：《高能物理与核物理》2006年第11期1067-1070,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+96Ru融合蒸发反应产生了近质子滴线核133Sm,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、第二代子核低位态之间的γ跃迁,并估计出衰变到第二代子核不同低位态的分支比．通过统计理论拟合上述实验数据,指认了133Sm的自旋宇称的可能范围．并用Woods-Saxon Strutinsky方法计算了限制组态的133Sm的核势能面,通过对比发现133Sm的自旋宇称可能有两种成分:5／2+和1／2-．这一结果与2001年发表的133Sm(EC+β+)衰变的简单衰变纲图是相容的．此外用同一方法分析了2001年Eur．Phys．J．A12: 1-4中发表的有关149Yb的β缓发质子衰变实验数据,由此指认了149Yb的基态自旋宇称为1／2-．^133Sm was produced via fusion evaporation in the reaction ^40Ca＋^96Ru. Its β-delayed proton decay was studied by means of ＂P-T＂ 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 possible spins and parities of ^133Sm were extracted by fitting the experimental data with a statistical model calculation. The configuration-constrained nuclear potential energy surfaces of ^133Sm were calculated by using the Woods-Saxon Strutinsky method. Comparing the experimental and calculated results, the spins and parities of ^133Sm were assigned to be 5/2^＋ and 1/2^-, which is reconciled with our published simple （EC＋β^＋） decay scheme of ^133Sm in 2001. In addition, our experimental data on the beta-delayed proton decay of ^149yb reported in Eur. Phys. J., 2001, A12：1-4 was also analyzed by using the same method. The spin and parity of ^149yb was assigned to be 1/2^-.

关 键 词：Β缓发质子衰变 核势能面 自旋 宇称 

分 类 号：O571.32[理学—粒子物理与原子核物理]