| Project/Area Number |
18K18759
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| Research Category |
Grant-in-Aid for Challenging Research (Exploratory)
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| Allocation Type | Multi-year Fund |
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| Review Section |
Medium-sized Section 15:Particle-, nuclear-, astro-physics, and related fields
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| Research Institution | Tohoku University |
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Principal Investigator |
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| Project Period (FY) |
2018-06-29 – 2022-03-31
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| Project Status |
Completed (Fiscal Year 2021)
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| Budget Amount *help |
¥6,240,000 (Direct Cost: ¥4,800,000、Indirect Cost: ¥1,440,000)
Fiscal Year 2020: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2019: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2018: ¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
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| Keywords | 核異性体 / トリウム / 核励起 / Th-229 |
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| Outline of Final Research Achievements |
Thorium with a mass number of 229, has a metastable state (Th-229m) with the lowest excitation energy of any nucleus known to date. The energy is reported to be 7.8 eV, which is about 1/1000 of the excitation energies of other nuclei. Our research is exploring the possibility of direct excitation of Th-229 using electron beams or lasers. In this study, we isolated Th-229 from several U-233 samples and investigated the possibility of using them for Th-229 excitation studies. In addition, we developed an apparatus to measure absorption spectra in the vacuum ultraviolet region and attempted to prepare samples for direct excitation experiments.
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| Academic Significance and Societal Importance of the Research Achievements |
本研究には，数eVの励起エネルギーを持つ特異な原子核状態であるTh-229mの直接励起の観測を目指すという基礎科学的な意義がある。今回，新たに入手することができたTh-229試料は原子核時計を含むTh-229研究に用いられるだけで無く，娘核種に核医学分野で注目されるAc-225など有用RIを含むため，本研究以外にも利用価値は大きい。また，本研究で開発された真空紫外照射・測定装置は，固体試料の真空紫外領域の吸光を簡便に測定することができ，今後目指していくTh-229直接励起研究のための基礎データ取得に役立つ。
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