Establishment of the nuclear energy-density functional method for a microscopic and systematic calculation of beta-decay rate

2023 Fiscal Year Final Research Report

• Project/Area Number: 19K03824
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 15010:Theoretical studies related to particle-, nuclear-, cosmic ray and astro-physics
• Research Institution: Osaka University (2022-2023); Kyoto University (2019-2021)
• Principal Investigator: Yoshida Kenichi 大阪大学, 核物理研究センター, 准教授 (00567547)
• Project Period (FY): 2019-04-01 – 2024-03-31
• Keywords: 中性子過剰核 / ベータ崩壊 / 元素合成 / 密度汎関数理論

Outline of Final Research Achievements

We have developed computational codes based on the nuclear energy-density-functional method to calculate the beta decay rates of unstable nuclei across a wide range of mass numbers. By taking not only allowed transitions but also first-forbidden transitions into account in deformed nuclei, this framework has become one of the most advanced. We formulated an approach that can be applied to beta decay in heavy neutron-rich nuclei where the Coulomb force is strong. Additionally, we analyzed excitation modes corresponding to higher-order forbidden transitions and compared them with experimental data to validate the adequacy of the energy-density functional employed in our current codes and calculations.

Free Research Field

原子核理論

Academic Significance and Societal Importance of the Research Achievements

重い元素の起源とされるr-過程元素合成では，中性子ドリップ線近傍に至る広い質量数領域にある不安定核の種々の反応が起きている。その中でもベータ崩壊は原子番号を大きくする過程であり，ベータ崩壊率はr-過程を記述する上で最も重要な反応率である。実験では到達できない重い中性子過剰核のベータ崩壊率を理論的に予言することが求められている中で，本研究では密度汎関数理論に基づき微視的に評価する手法を開発した。