New Aspects of Nuclear Deformation

本课题从动态和静态两方面对核四极和八极变形进行了新的研究。我们使用的理论工具是相互作用玻色子模型（IBM）。已知的伽马不稳定变形是质量数为130的Xe和Ba核。我们特别研究了^<130>Xe的结构，以便研究在这个核中O(6)动力学对称性保持到什么程度。Koeln组采集的数据非常清楚地表明了O(6)动力学对称性。O(6)动态对称是一个完美的描述，但似乎相当抽象。大冢对其结构进行了新的诠释。O(6)动力对称可以看作是形变平衡中的声子激发。有了这种观点，就可以对伽马不稳定核的结构有更直观的认识。从转动阻尼和宽度两个方面对量子混沌进行了研究。O(6)核的磁跃迁异常增强，并对Koeln组最近采集的数据进行了分析。用相互作用玻色子-费米子模型- 2分析了Koeln群对奇a核的Ml激发数据。用玻色子-费米子相互作用模型- 2研究了^<125,127>Xe的原子核，实验结果与计算结果吻合较好。

In this research project, nuclear quadruple and octupole deformations have been studied from various new aspects, including both dynamical and static deformations. The theoretical tool we have used is the Interacting Boson Model (IBM). The gamma-unstable deformation is known for Xe and Ba nuclei with the mass number-130. We studied the structure of ^<130>Xe, in particular, in order to investigate to what extent the O(6) dynamical symmetry holds in this nucleus. The data taken by Koeln group indicates very clearly the O(6) dynamical symmetry properties. The O(6) dynamical symmetry is a perfect description, but appears to be rather abstract. Otsuka developed a new interpretation of its structure. The O(6) dynamical symmetry can be viewed as the phonon excitation from a deformed equilibrium. With this view, a more intuitive understanding of the structure of gamma-unstable nuclei can be obtained. The quantum chaos has been studied in terms of the rotational damping and the width. The magnetic transitions are enhanced anomalously in the O(6) nuclei, and data taken recently by the Koeln group have been analyzed. The Interacting Boson-Fermion Model - 2 has been used to analyze the Ml excitation data by the Koeln group for odd-A nuclei. The nuclei ^<125,127>Xe have been studied in terms of the Interacting Boson-Fermion Model - 2, and a good agreement between experiment and calculation has been obtained.