Monte-Carlo Shell Model

本课题旨在研究量子多体系统中不稳定原子核的未知结构，探索原子核中核力的隐藏效应。此外，我们还旨在揭示在不稳定区域可能出现的新的多体机制。为此，我们基于蒙特卡罗壳模型方法和其他相关方法，对核图中包括不稳定核在内的广泛区域的核进行了统一的系统研究。我们获得了一个由232个cpu组成的大型并行计算机系统，用于量子多体系统的数值模拟。蒙特卡罗壳模型使我们能够进行各种计算，这是其他传统方法无法实现的。结果，在质子数(Z)约为10的原子核区域，我们发现了使中子幻数N=20消失而出现新的幻数N=16的机制。定量评价了这一机制对能量谱和电磁矩的影响，并给出了幻数变化的精确预测。我们首次成功地对pf壳层核进行了统一描述，评估了Gamow-Teller跃迁强度，并将其应用于天体物理学。我们对质量在130左右的重核进行了微观研究，进行了能级、电磁跃迁概率和矩的理论计算，与实验值吻合较好。我们还发现了由张量力产生的壳演化，呈现出主要由壳演化引起的不稳定原子核结构的奇异特征。此外，人们还取得了许多其他的成就，例如发现了原子核的三角形。目前已发表原创论文70篇。该项目促进了与包括日本以外的许多研究小组的合作，并为国际会议做出了重大贡献，其中包括78次特邀演讲。随着学科的迅速发展和研究对象的多样化，我们聘请了年轻的物理学家，并在学期末举行了一次国际研讨会。少

The purpose of this project was to study unknown structure of unstable nudei which are quantum many-body systems, and to explore hidden effects of the nuclear force in nuclei. Moreover we aimed to reveal new many-body mechanisms which may appear in the unstable regions. For these purposes, we performed unified systematic studies of the nuclei in broad regions of the nuclear chart including unstable nuclei, based on the Monte-Carlo Shell Model method and other relevant approaches. We acquired a massive parallel computer system consisting of 232 CPUs for the numerical simulation of a quantum many-body system. The Monte-Carlo Shell Model enables us to perform various calculations which had not yet been made possible by other conventional methods.As a result, in the region of nuclei whose proton number (Z) is around 10, we found the mechanism which makes the neutron magic number N=20 disappears and a new magic number N=16 emerges. We also evaluated quantitatively how the mechanism affects … More the energy spectra and the electromagnetic moments, and provided with the precise predictions of the places where the magic number will be changed. We succeeded in the unified description of the pf shell nuclei, for the first time, evaluating the Gamow-Teller transition strength, and applying it to astrophysics. We have carried out microscopic studies of heavy nuclei whose masses are around 130, performing the theoretical calculation of energy levels, electromagnetic transition probabilities and moments, in good agreement with the experimental values. We also discovered the shell evolution emerged by the tensor force, presenting exotic features of the structure of the unstable nuclei, caused primarily by the shell evolution. Inaddition, much other achievement has been done such as the discovery of the triangular shape of nuclei. So far, 70 original papers have been published.This project promoted collaborations with many research groups including those outside Japan, and made significant contributions to international conferences including 78 invited talks. With the rapid developments and the diversity of the studied subjects, we employed young physicists, and held an international symposium at the end of the term. Less