Elucidation of the nuclear decay property of Th-229m utilizing Ac-229
Project/Area Number |
19K23445
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Research Category |
Grant-in-Aid for Research Activity Start-up
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Allocation Type | Multi-year Fund |
Review Section |
0203:Particle-, nuclear-, astro-physics, and related fields
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Research Institution | Institute of Physical and Chemical Research |
Principal Investigator |
Shigekawa Yudai 国立研究開発法人理化学研究所, 仁科加速器科学研究センター, 基礎科学特別研究員 (60845626)
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Project Period (FY) |
2019-08-30 – 2021-03-31
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Project Status |
Completed (Fiscal Year 2020)
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Budget Amount *help |
¥2,860,000 (Direct Cost: ¥2,200,000、Indirect Cost: ¥660,000)
Fiscal Year 2020: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2019: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
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Keywords | トリウム229 / 原子核時計 / アクチニウム / プロトアクチニウム / Th-229m / 核異性体 / 真空紫外光 / 229mTh |
Outline of Research at the Start |
229mThは229Th原子核の第一励起準位であり,8 eV程度と極端に低い励起エネルギーを持つ.基底状態の229Thをレーザーにより229mThに核励起できれば,超高精密な原子核時計を実現できると期待されている.核励起に必要なレーザーの条件を決定するために,本研究では,229mThの励起エネルギーを0.1 eV程度の精度で決定し,229mThのγ線放出半減期を決定することを目的とする.それらを実現するために,229Acを用いた新しい手法によって229mThを適切な化学状態に制御した上で,229mThの内部転換電子分光測定およびγ線測定を行う.
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Outline of Final Research Achievements |
We aimed to inhibit the internal conversion process of Th-229m and observe its γ-ray emission process using the new method in which a fluoride crystal is doped with Ac-229 or Pa-229. We developed a method for producing a large amount of Pa-229 using an accelerator and separating it from a target and fission products with high efficiency. We also developed an apparatus for measuring γ rays (VUV photons) originating from the decay of Th-229m. Using a CaF2 crystal on which a Pa-229 solution was heated, we measured background photons originating from the decay of Pa-229. We will be able to clearly observe the γ rays of Th-229m by improving the method for introducing Pa-229 into a CaF2 crystal.
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Academic Significance and Societal Importance of the Research Achievements |
本研究課題では、今まで誰も観測に成功していないTh-229mのγ線放出過程の直接観測を目指して、Ac-229やPa-229を用いた手法を新しく開発した。手法をさらに改善することで、Th-229mのγ線を観測し、Th-229原子核時計を開発する上で重要なパラメータであるγ線放出の半減期を決定できると期待される。将来的に既存の原子時計よりも精度の高い原子核時計を実現できれば、基礎物理学や測地学などの発展に大きく貢献できる。
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Report
(3 results)
Research Products
(13 results)
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[Journal Article] Co-precipitation behaviour of single atoms of rutherfordium in basic solutions2021
Author(s)
Y. Kasamatsu, K. Toyomura, H. Haba, T. Yokokita, A. Kino, Y. Yasuda, Y. Komori, J. Kanaya, M.H. Huang, M. Murakami, H. Kikunaga, E. Watanabe, T. Yoshimura, K. Morita, T. Mitsugashira, K. Takamiya, T. Ohtsuki, A. Shinohara
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Journal Title
NATURE CHEMISTRY
Volume: 13
Issue: 3
Pages: 226-230
DOI
Related Report
Peer Reviewed
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[Journal Article] Absolute X-ray energy measurement using a high-accuracy angle encoder2021
Author(s)
Masuda Takahiko、Watanabe Tsukasa、Beeks Kjeld、Fujimoto Hiroyuki、Hiraki Takahiro、Kaino Hiroyuki、Kitao Shinji、Miyamoto Yuki、Okai Koichi、Sasao Noboru、Seto Makoto、Schumm Thorsten、Shigekawa Yudai、Tamasaku Kenji、Uetake Satoshi、Yamaguchi Atsushi、Yoda Yoshitaka、Yoshimi Akihiro、Yoshimura Koji
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Journal Title
Journal of Synchrotron Radiation
Volume: 28
Issue: 1
Pages: 111-119
DOI
NAID
Related Report
Peer Reviewed / Open Access / Int'l Joint Research
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[Journal Article] Half-life determination of nuclear excited states of 229Th by the coincidence measurement between α particles and γ rays from 233U2020
Author(s)
Y. Shigekawa, A. Yamaguchi, K. Suzuki, H. Haba, T. Hiraki, H. Kikunaga, T. Masuda, S. Nishimura, N. Sasao, A. Yoshimi, and K. Yoshimura
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Journal Title
RIKEN Accel. Prog. Rep.
Volume: 53
Pages: 51-51
Related Report
Peer Reviewed
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