Chaos and damped collective motions in highly excited nuclei

在本研究中，我们研究了原子核在非常高自旋和有限但中等温度下的旋转运动阻尼。特别是，我们重点研究了旋转阻尼现象与复合态形成之间的关系，这是高激发核的最基本特征之一。复合阻尼宽度是对高激发能级波函数复杂性的动态度量。我们澄清了这个量在与阻尼旋转运动相关的准连续统伽马射线的能量相关谱中以双组分结构出现。这首次指出了在实验中探测复合阻尼宽度的可能性。我们还研究了旋转阻尼现象的系统学，阐明了与壳结构效应相关的重要质量数依赖性。并对最近的实验数据进行了分析。提出了一种新的方法来分析与阻尼集体运动有关的强度函数中的一般波动和精细结构。为此，我们引入了局部尺度维的新概念，并通过实例说明了其适用性。

In the present research, we investigated the damping of rotational motion in nuclei at very high spin and at finite but moderate temperature. Especially, we focused on studies to clarify a relation between the rotational damping phenomena and the formation of compound states, which is one of the most basic features in the highly excited nuclei.The compound damping width is a dynamical measure of complexity of the wavefunctions of highly excited levels. We clarified that this quantity emerges as a two-component structure in the energy correlation spectra of quasi-continuum gamma rays associated with the damped rotational motion. This points out for the first time a possibility of probing the compound damping width in the experiments.We also studied the systematics of the rotational damping phenomena, clarifying a significant mass number dependence associated with a shell structure effect. An analysis of recent experimental data is also performed.A new method is proposed to analyze in a general manner fluctuations and fine structures in the strength function associated with the damped collective motions. For this purpose, we introduced a new concept of the local scaling dimension, and demonstrated its applicability for some examples.