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

核是一个有限的量化系统，那里观察到许多现象，可以通过集体和独立的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旋转和高度激发的极端状态下观察到的现象。在这项研究中，我们研究了与使用简单的隧道模型引起的各种与“相变”或“相位折射”相关的现象。这种现象是极端变形状态向正常变形状态的过渡。进行系统的计算，我们发现势能表面被认为在超高频带的各个观察到的区域都不同。此外，我们已经将先前发明的隧道模型扩展到了激发态，并通过包括EF（更多的衰减事实）成功地重现了激发的超级型带的数量。第二项研究是旋转自由度的旋转自由度的隧道。已经观察到的是，高自旋异构体围绕对称轴旋转，衰减到yrast旋转带的衰减，它们围绕垂直于对称轴的轴旋转。这样的衰减可以理解为在三方形成度或自由的倾斜角度中的过渡。我们已经成功地开发了一种计算势能表面相对于这些自由度的方法，并一直在研究同一基础上的两个自由度。在本文中，我们还研究了核有效质量，这对于研究高旋转和极为激发的极端状态很重要，考虑到集体形状自由度的耦合效应。我们发现，耦合效应在高旋转极限下大大降低了，这会导致例如核水平密度的重要变化。较少的

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。