| Project/Area Number |
18H03703
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Review Section |
Medium-sized Section 15:Particle-, nuclear-, astro-physics, and related fields
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| Research Institution | Osaka University |
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Principal Investigator |
AOI Nori 大阪大学, 核物理研究センター, 教授 (00311647)
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| Project Period (FY) |
2018-04-01 – 2021-03-31
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| Project Status |
Completed (Fiscal Year 2022)
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| Budget Amount *help |
¥44,330,000 (Direct Cost: ¥34,100,000、Indirect Cost: ¥10,230,000)
Fiscal Year 2020: ¥13,000,000 (Direct Cost: ¥10,000,000、Indirect Cost: ¥3,000,000)
Fiscal Year 2019: ¥16,120,000 (Direct Cost: ¥12,400,000、Indirect Cost: ¥3,720,000)
Fiscal Year 2018: ¥15,210,000 (Direct Cost: ¥11,700,000、Indirect Cost: ¥3,510,000)
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| Keywords | 超変形 / 変形共存 / 変形混合 / 40Ca / 核構造 / ガンマ線核分光 / ハイパー変形 / ガンマ線トラッキング検出器 / 原子核物理 |
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| Outline of Final Research Achievements |
The electric monopole strength was determined by measuring the e+e- decay of calcium-40 from the superdeformed state (3rd-0+ state) to the spherical state (1st=0+ state). The obtained value is extremely small, the smallest among nuclei with mass numbers below 50. It was found that the spherical, normally deformed, and superdeformed states are not pure, but are mixed with each other and interfere with each other so as to weaken the transition from the superdeformed state to the spherical state.
To trace the deformation transition in the neutron-rich upper right region of the calcium-40 nucleus, the electric quadrupole transition strength, which is the physical quantity that reflects deformation most directly, was determined from the Coulomb excitation cross sections of 56Ti and 56Ti.
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| Academic Significance and Societal Importance of the Research Achievements |
古典的な液滴では常に球形が安定であるのに対し、原子核では量子効果によって変形状態が安定化することが多い。さらに、複数の異なる形状の状態が基底状態付近に現れそれらの状態が混合する変形混合現象が起こることもある。カルシウム-40原子核では球形と通常変形と超変形の状態が基底状態付近に存在するが、今回の研究では3つの状態が混合し合い、互いの状態の遷移強度に干渉効果をもたらしていることが分かった。球形状態と超変形状態という非常に異なる内部構造を持った状態が混合するという現象は核分裂などの量子多体系のダイナミクスを理解する上で重要な役割を果たす。
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