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对清华大学在束γ谱实验组近年来在A=135缺中子核区N=79的同中异位素135Ba,137Ce和139Nd的高自旋态实验研究进行了介绍。实验是在中国原子能科学研究院HI-13串列加速器上用在束γ的实验技术、分别通过重离子核反应130Te(9Be,4n),124Sn(18O,5n),128Te(16O,5n)进行的。实验结果扩展了这3个核的高自旋态能级纲图。研究表明,这3个核的低自旋态结构均起源于νh1-1/12空穴与其偶偶核芯的耦合。用粒子-转子模型对其结构进行了计算,得到这3个核的形变参量γ值均稍大于30°,为偏向于扁椭的三轴形变,从而可看出Ba,Ce和Nd3个同位素链在低自旋态下由长椭边到扁椭边的形状转变都发生在中子数N=77—79之间。对于中等自旋态下一些能级的组态进行了指定与系统学比较。在高自旋态下,在137Ce中发现一条γ≈-60°的扁椭形变带,在139Nd中则发现3条这样的扁椭形变带,对这些扁椭形变带的起源及结构特性进行了讨论。
Tsinghua University in beam γ spectroscopy experimental group in recent years in the A = 135 neutrino nucleus N = 79 of the same isotopes of isotopes 135Ba, 137Ce and 139Nd high spin state experimental study is introduced. The experiments were performed on the HI-13 tandem accelerator of China Institute of Atomic Energy using the experimental technique of beam γ, respectively by heavy ion nuclear reaction 130Te (9Be, 4n), 124Sn (18O, 5n), 128Te (16O, 5n) . The experimental results extend the high-spin energy levels of these three cores. The results show that the low-spin structures of these three nuclei all originate from the coupling of vh1-1 / 12 holes with their even-numbered cores. The particle-rotor model is used to calculate the structure. The deformation parameters γ of the three nuclei are all slightly larger than 30 °, which is the triaxial deformation that is inclined to the flat ellipse. Thus we can see that there are three isotopic chains of Ba, Ce and Nd The shape transition from ellipsoid to oblate edge in the low spin state occurs between neutrons N = 77-79. The configurations of some energy levels under intermediate spin states were specified and compared systematically. In the high spin state, a flat oval band of γ≈-60 ° was found in 137Ce, and three such flat oval bands were found in 139Nd. The origin and structural characteristics of these flat oval bands were discussed.