Development of an experimental method to determine the nuclear radii of isomeric states through reaction cross sections and its application to astrophysics

2019 Fiscal Year Final Research Report

• Project/Area Number: 16H03905
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Quantum beam science
• Research Institution: Osaka University
• Principal Investigator: Fukuda Mitsunori 大阪大学, 理学研究科, 准教授 (50218939)
• Co-Investigator(Kenkyū-buntansha): 西村 太樹 東京都市大学, 共通教育部, 准教授 (30612147) ; 武智 麻耶 新潟大学, 自然科学系, 助教 (40570172)
• Project Period (FY): 2016-04-01 – 2019-03-31
• Keywords: 核半径 / アイソマー状態 / 反応断面積 / 元素合成 / リングイメージングチェレンコフ検出器

Outline of Final Research Achievements

The isomeric state, which is the excited state of nuclei, is not only a very interesting research subject in nuclear physics, but its importance is pointed out also in astrophysics, but due to its short life, nuclear radius measurement was difficult. Therefore, we aimed to establish a method to measure the radius of the isomeric-state nucleus using a physical quantity called the reaction cross section, which corresponds to the probability of nuclear collision. As a result, we found that the 16N(0-) isomeric state with a half-life of only 5 μs seems to have a nuclear radius that is significantly different from that of the ground state by measuring reaction cross sections. This result is expected to contribute to a more accurate estimation of the rate of nucleosynthesis by nuclear reactions in the universe, especially in the process of the big bang.

Free Research Field

実験原子核物理学

Academic Significance and Societal Importance of the Research Achievements

16N(0-)アイソマー状態の核半径についての情報が得られたことは、この状態の原子核構造に対する重要な知見が得られたというだけでなく、宇宙環境における元素合成の理解に大いに寄与する。開発した新しいアイソマー状態の核半径決定法は、同様な宇宙物理で興味が持たれるアイソマー状態の核構造決定に利用できる。また、研究の過程で開発した新しい粒子検出器群、例えば重イオン用リング・イメージング・チェレンコフ検出器（速度分解能 0.05 %）は、他の実験核物理分野の多くの研究に利用できる。