Nuclear structure at extreme
Project/Area Number  10044339 
Research Category 
GrantinAid for International Scientific Research.

Section  Joint Research . 
Research Field 
素粒子・核・宇宙線

Research Institution  The University of Tokyo 
Principal Investigator 
YAZAKI Koichi The University of Tokyo, Graduate School of Science, Professor, 大学院・理学系研究科, 教授 (60012382)

CoInvestigator(Kenkyūbuntansha) 
RENZO Leonar 原子核理論及び関連領域における理論研究のためのヨーロッパセンター, 教授
MIZUSAKI Takahiro The University of Tokyo, Graduate School of Science, Research Associate, 大学院・理学系研究科, 助手 (50251400)
OTSUKA Takaharu The University of Tokyo, Graduate School of Science, Professor, 大学院・理学系研究科, 教授 (20201379)
LEONARDI Renzo European Center for Theoretical Studies in Nuclear Physics and Related Areas Pro

Project Fiscal Year 
1998 – 1998

Project Status 
Completed(Fiscal Year 1998)

Keywords  Isospin / beta stability line / stable nucleus / unstable nucleus / closed shell / 32Mg / magic number / Monte Carlo shell model / アイソスピン / ベータ安定線 / 安定核 / 不安定核 / 閉殻 / 魔法数 / モンテカルロ殻模型 / 高スピン状態 / 高アイソスピン状態 / 量子モンテカルロ対角化法 / トレント / ect / 極限状態 / 原子核構造 / 殻模型 
Research Abstract 
In this research project, the nuclear structure has been studied at variousextremes. We first investigated the structure of nuclei at high isospin. High isospin indicates situations that the neutron number is greater than theproton number or vice versa. The zcomponent of isospin is given by (ZN)/2 where Z and N mean the proton and neutron numbers, respectively. The magnitude of isospin, T, should be larger than or equal to Tz. In nuclei with equal numbers of neutrons and protons, Tz=0, and the ground and lowlying states are of T0. Lowisospin corresponds to the nuclei on and near the beta stability line (stable nuclei) where the proton and neutron numbers are equal or close to each other. On the other side, nuclei with large T are far from the beta stability line, being called unstable nuclei. It has been clarified during the past ten years that unstable nuclei have structure very different from the structure of stable nuclei. In this project, we studied 32Mg, which is an example of unstable nuclei, and its vicinity. The N20 is a magic number as well known. Therefore, on the standpoint of stable nuclei, 32Mg should be a neutronclosed nucleus, and should have a spherical ground state. This has been shown to be incorrect, experimentally and theoretically. On the contrary, studies on nuclei around 32Mg have hardly been done. We can now, however, carry out such studies by using the Monte Carlo shell model being developed by the group of the University of Tokyo. By such studies, it has been clarified that the change from stable nuclei does not occur suddenly at a certain nucleus but does occur gradually, and that the monopole component of the effective interaction plays a crucial role in this. In addition to the above studies, the sphericaldeformed transition has been studied including high spin states.

Report
(3results)
Research Output
(3results)