Occurrence of a chiral-like pair band and a six-nucleon noncollective oblate isomer in I-120
Occurrence of a chiral-like pair band and a six-nucleon noncollective oblate isomer in I-120
复制标题
I-120 中出现手性对带和六核子非集体扁圆异构体
DOI：
10.1016/j.physletb.2018.06.008
复制
发表时间：
2018
影响因子：
4.4
通讯作者：
Hong B.
中科院分区：
文献类型：
--
作者：
Moon B.;Moon C.-B.;Dracoulis G.D.;Bark R.A.;Byrne A.P.;Davidson P.A.;Lane G.J.;Kibédi T.;Wilson A.N.;Yuan C.;Hong B.
首次报道了奇-奇核120 I的两个显著特征：一对二重态带和一个建立在π h 11/2 ν h 11/2组态上的高自旋同质异能态.为了产生120 I的激发态，采用了E= 1a B 48 MeV的118 Sn（6 Li，4 n）聚变蒸发反应。该束由澳大利亚国立大学重离子加速器设施的14 UD串列加速器提供。在正宇称态上观察到的双重结构是第一种情况，在Z= 53的同位素中是唯一的。新出现的性质表明了已知的手征特征，导致π h 11/2 ν h 11/2组态的态加倍。相比之下，在自旋宇称J π= 25+时半衰期为49（2）ns的高自旋异构体可以用非集体扁圆结构来解释，该结构在114 Sn核外有六个价核子完全排列：三个质子（g 7/2）1（d 5/2）1（h 11/2）1和三个中子（h 11/2）3。这是一个突出的情况下，揭示了一个纯粹的单粒子结构，包括相等数量的价质子和中子的半双壳层封闭的114锡与Z= 50和N= 64。
We report for the first time two distinctive features in the odd–odd nucleus 120 I: a pair of doublet bands and a high-spin isomer built on the π h 11/2 ν h 11/2 configuration. For producing the excited states of 120 I, a fusion-evaporation reaction 118 Sn (6 Li, 4n) at E= l a b 48 MeV was employed. The beam was provided by the 14UD tandem accelerator of the Heavy Ion Accelerator Facility at the Australian National University. The observed doublet structure built on the positive-parity states is the first case and unique in isotopes with Z= 53. The emerging properties are indicative of the known chiral characteristics, leading to a doubling of states for the π h 11/2 ν h 11/2 configuration. In contrast, the high-spin isomer with a half-life of 49 (2) ns at spin-parity J π= 25+ can be explained in terms of a noncollective oblate structure with the full alignment of six valence nucleons outside the 114 Sn core: three protons (g 7/2) 1 (d 5/2) 1 (h 11/2) 1 and three neutrons (h 11/2) 3. This is an outstanding case that reveals a pure single-particle structure consisting of equal numbers of valence protons and neutrons outside the semi-double shell closure of 114 Sn with Z= 50 and N= 64.