Structure change of 156Yb at high-spin states

High-spin states of ¹⁵⁶Yb have been studied via the ¹⁴⁴Sm(¹⁶O,4n)¹⁵⁶Yb fusion-evaporation reaction at beam energy 102~MeV. The positive-parity yrast band and negative-parity cascade have been extended up to higher-spin states, respectively. The characteristics of the negative-parity sequence above the 25^－ state may related to the excitation from the nucleon in the Z=64, N=82 core. The E-GOS curve for the positive-parity yrast sequence in ¹⁵⁶Yb indicate that this nucleus may undergo an evolution from quasivibrational to quasirotational structure with increasing angular momentum. The Cranked Woods-Saxon-Strutinsky calculations by means of Total-Routhian-Surface (TRS) methods has been made to understand this structure change.     

Triaxiality of High-K Isomers in A~130 Region

Remarkable triaxiality is found in the high-K isomeric states of A-130 nuclei using the configuration-constrained calculations of potential-energy surfaces. The triaxiality gives the further understanding of the decay properties of the isomers. The calculation with triaxiality can well explain the measured quadrupole moment of the K^z=7^- isomer in ^130Ce.     

130Ce的Kπ=7－同核异能态的形状研究

用组态限制的方法研究了¹³⁰Ce的K^π=7^－同核异能态的形状. 计算的激发能与实验值很好地符合. 计算得到的形变表明这个同核异能态具有大小和基态大致一样的长椭球形状. 不过, 它的势能面在γ自由度上非常软, 这很可能是导致其K混合的原因.     

140Tb和141Dy的β缓发质子衰变以及143Dy的自旋宇称

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.     

152Gd核高自旋态的研究

利用¹⁴⁸Nd(⁹Be, 5n)¹⁵²Gd重离子熔合蒸发反应, 对¹⁵²Gd(Z=64, N=88)核的高自旋态进行了研究. 在¹⁵²Gd核中发现了10多个新的高自旋能级和一个新的S带结构. 实验中首次观察到¹⁵²Gd核完整的第一个带交叉, 与推转壳模型计算结果和邻近核实验结果的比较显示带交叉是由一对i_13/2中子的顺排造成的. 通过对¹⁵²Gd核运动学转动惯量的分析, 得到¹⁵²Gd核的形状随着自旋变化的实验证据.     

Oblate Superdeformed High-K States in Superheavy Nuclei

Configuration-constrained calculations of potential -energy surfaces for292122 show the occurrence of multiquasiparticle high-K isomeric state at oblate superdeformation. Such state could play a unique role in superheavy nuclei,with possible long life time from enhanced difculty in fission due to additional barrier at oblate deformation, retardation in α decay due to unpaired nucleons, and hindrance in γ-ray transition due to K forbiddenness.     

133Sm和149Yb的β缓发质子衰变

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^－.     

Shape coexistence of high-spin isomeric states in proton-rich A~190 nuclei

High-spin isomeric states in proton-rich A~190 nuclei have been investigated using configuration-constrained calculations of potential-energy surfaces. The calculations reproduce reasonably the experimental data, and predict shape coexistence of high-spin isomeric states in light Po isotopes.