Theoretical Study of Phase-Coexistence Phenomena in Rapidly Rotating Nuclei

快速旋转原子核中相共存现象的理论研究

• 批准号: 10640275
• 负责人: SHIMIZU Yoshifumi
• 金额: $ 1.28万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 1999
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10640275/
• 关键词: nuclear rotation; high-spin state; cranking model; tilted axis cranking; shape coexistence; high-spin isomer; superdeformation; effective mass; 核分光学; 傾向クランキング

Nucleus is a finite quantal system and there observed many phenomena, which can be understand by an interplay between the collective and independent degrees of freedoms. Especially interesting phenomena are those observed recently at high-spin and highly excited extreme states. In this research we have studied various kinds of such phenomena related to the "phase-transitions" or "phase-coexistences"caused by the nuclear-shape and rotation degrees of freedoms by using a simple tunneling model.The first one is the decay-out of superdeformed rotational bands. This phenomenon is a transition of extremely deformed states to normally deformed states. Performing systematic calculations, we have found that the potential energy surfaces are considerably different in various observed regions of superdeformed bands. Furthermore, we have extended the previously invented tunneling model to excited states, and have successfully reproduced the number of excited superdeformed bands by including the ef … More fect ofdecay-out.The second research is the tunneling in the tilting-angle degrees of freedom of rotaitonal axis. It has been observed that the high-spin isomers, which are rotating around the symmetry-axis, decay to the yrast rotational bands, which are rotating around axis perpendicular to the symmetry-axis. Such decays can be understood as transitions either in the triaxial-deformation degrees or in the tilting-angle degrees of freedoms. We have successfully developed a method to calculate the potential energy surface with respect to these degrees of freedoms, and been studying two degrees of freedoms on the same footing.Finally, we have also investigated the nucleon effective mass, which is important to study the high-spin and highly excited extreme states, taking into account of the coupling effects of collective shape degrees of freedoms. We have found that the coupling effects reduces very much at high-spin limits, and it causes an important change to, for example, the nuclear level-density. Less

原子核是一个有限的量子系统，在那里观察到许多现象，这些现象可以通过集体自由度和独立自由度之间的相互作用来理解。特别有趣的现象是最近在高自旋和高激发极端状态下观察到的。本研究利用简单的隧道模型研究了与核形状和旋转自由度引起的“相变”或“相共存”有关的各种现象：第一种是超变形旋转带的衰变。这种现象是极端变形状态向正常变形状态的转变。通过系统的计算，我们发现在超形变带的不同观测区域，势能面有很大的不同。此外，我们还将先前发明的隧穿模型推广到激发态，并通过引入ef，成功地再现了激发态超形变带的数目。 ...更多信息 第二个研究的是旋转轴倾角自由度的隧穿。已经观察到，高自旋的异构体，这是旋转轴周围的自旋轴，衰变到yraast旋转带，这是旋转轴垂直于自旋轴。这种衰减可以理解为三轴变形度或倾斜角自由度的过渡。我们成功地发展了一种计算与这些自由度有关的势能面的方法，并在同一基础上研究了两个自由度，最后，我们还考虑了集体形状自由度的耦合效应，研究了对研究高自旋高激发极端态很重要的核子有效质量。我们发现，在高自旋极限下，耦合效应大大减小，并引起核能级密度等重要变化。少

项目成果

M. Sato: "Test of Validity of the Hemitian Treakment of the Dyson Boson Mapping"Prog. Of Theor. Phs.. 102. 287-296 (1999)

M. Sato：“戴森玻色子映射的赫米特处理的有效性检验”Prog。

M. Sato: "Test of Validity of the Hermitian Treatment of the Dyson Boson Mapping"Prog. of Theor. Phys. Vol. 102, No.2. 287-296 (1999)

M. Sato：“戴森玻色子映射的埃尔米特处理的有效性测试”Prog。

M.Sato: "Test of Validity of the Hermitian Treatment of the Dyson Boson Mapping"Progress of Theoretical Physics. 102・2. 287-296 (1999)

M.Sato：“戴森玻色子映射的埃尔米特处理的有效性检验”理论物理学进展102・2（1999）。

T.Hayakawa: "Rotational Bands of 155Gd"Nuclear Physics. Vol. A657, No.1. 3-18 (1999)

T.Hayakawa：“155Gd 的旋转带”核物理。

P.Donati: "A Complex Integration Technique to Remove Spurious States Associated with Spontaneously Broken Symmetries in RPA Calculations" Nuclear Physics A. 発表予定.

P.Donati：“一种复杂的积分技术，用于消除 RPA 计算中与自发破缺对称性相关的杂散态”核物理 A. 待提交。