2023 Fiscal Year Final Research Report

Charge polarization of fission fragments connects microscopic theoretical research and applied research

Research Project

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Project/Area Number	20K03943
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	Saitama University
Principal Investigator	Ebata Shuichiro 埼玉大学, 理工学研究科, 助教 (40614920)
Co-Investigator(Kenkyū-buntansha)	吉永尚孝埼玉大学, 理工学研究科, 名誉教授 (00192427) 千葉敏東京工業大学, 科学技術創成研究院, 教授 (60354883)
Project Period (FY)	2020-04-01 – 2024-03-31
Keywords	核分裂 / 原子核構造 / 微視的平均場模型 / 原子核理論物理 / 核データ
Outline of Final Research Achievements	We focused on the charge polarization (CP) of nuclear fission fragments and performed the study based on the microscopic mean-field theory to investigate their configurations and densities. We found that the CP adiabatically deduced by the static method imposing the constraints on nuclear shape depends on the nuclear shell structure. However, the magnitude of the CP was insufficient to reproduce the neutron yields emitted at the fission, indicating other factors to form the large CP. Although we investigated the nuclear interaction and pairing correlation dependences for the CP, we especially considered the possibility of a dynamic effect. Thus, we developed and performed the time-dependent mean-field model to deduce the CP. The dynamic calculations were performed to calculate the configuration and CP of the fission fragments newly, using the adiabatically obtained configurations as the initial states. We showed this CP enlarges enough to reproduce the neutron yield.
Free Research Field	原子核物理
Academic Significance and Societal Importance of the Research Achievements	これまでにも微視的平均場模型を用いて、核分裂を研究する方法はあったが、質量数に関する核分裂片の収率に注目する方法が多く、原子核構造研究から分裂片の荷電偏極に注目する方法はこれまでに無かった。原子核の形状に関する拘束条件を課した断熱的な方法では、十分な荷電偏極は得られない事が分かった。一方で励起状態を取り入れた時間依存平均場模型による計算では、即発中性子収量の平均値を再現する十分な荷電偏極を得る事が出来た。微視的理論模型から原子力工学で利用されるデータにアプローチ出来る事を示した成果は、学術的な意義が大きいと考える。