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Observing the electron bridge process of the Th-229 isomer utilizing ion-molecule reactions

Research Project

Project/Area Number 20K14500
Research Category

Grant-in-Aid for Early-Career Scientists

Allocation TypeMulti-year Fund
Review Section Basic Section 15020:Experimental studies related to particle-, nuclear-, cosmic ray and astro-physics
Research InstitutionInstitute 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, 特別研究員 (60845626)

Project Period (FY) 2020-04-01 – 2023-03-31
Project Status Completed (Fiscal Year 2022)
Budget Amount *help
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2022: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2021: ¥1,300,000 (Direct Cost: ¥1,000,000、Indirect Cost: ¥300,000)
Fiscal Year 2020: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
Keywordsトリウム229 / 電子架橋遷移 / 核異性体 / イオントラップ / RFカーペット / ガスセル / イオン分子反応 / 原子核時計 / 電子架橋
Outline of Research at the Start

Th-229m(Th-229原子核の第一励起準位)は8.3 eV程度の極端に低い励起エネルギーを持つため,「電子架橋遷移」という特異な過程により脱励起する可能性が予測されている.電子架橋遷移では,原子核の励起エネルギーの一部が軌道殻電子の電子遷移に費やされ,余剰分のエネルギーが光子として放出される.本研究では,世界で初めて電子架橋遷移を明確に観測し,電子架橋遷移の性質を解明することを目指す.そのために様々な電子状態のTh-229mイオンをイオンー分子反応によりイオントラップ中で生成・制御する技術を開発し,電子架橋遷移由来の光子を放出するTh-229mイオンを探索する.

Outline of Final Research Achievements

The first excited state of the Th-229 nucleus, Th-229m, has an excitation energy of 8.3 eV. This extremely low isomeric energy would allow the deexcitation by the electronic bridge process, which is a higher order process than the gamma-ray emission and the internal conversion process. In this project, we aim to observe the electronic bridge process for the first time using singly charged Th-229m ions produced by the reaction between doubly charged Th-229m ions and reactive gaseous molecules. We first developed an ion-extraction and ion-trap apparatus, and then we successfully extracted and trapped doubly charged Th-229m ions recoiling out of a U-233 source. Moreover, we were able to produce singly charged Th-229m ions by the chemical reaction in the ion trap.

Academic Significance and Societal Importance of the Research Achievements

本研究課題では、2価や3価のTh-229mイオンの引き出しと、イオン分子反応を利用した1価のTh-229mイオンの生成に成功した。1価のTh-229mイオンでは電子架橋遷移によって壊変する可能性が高いと理論的に予測されているため、本研究で開発した装置を用いることで、近日中に新規の核現象である電子架橋遷移を世界で初めて観測できる期待が高まる。一方、本研究で開発された多価のTh-229イオン引き出し技術は、超高精密なTh-229原子核時計の実現に極めて重要である。本技術を利用して原子核時計を開発できれば、基礎物理学や測地学などの発展に大きく貢献できると期待される。

Report

(4 results)
  • 2022 Annual Research Report   Final Research Report ( PDF )
  • 2021 Research-status Report
  • 2020 Research-status Report
  • Research Products

    (33 results)

All 2023 2022 2021 2020

All Journal Article (18 results) (of which Int'l Joint Research: 3 results,  Peer Reviewed: 18 results,  Open Access: 8 results) Presentation (15 results) (of which Int'l Joint Research: 3 results,  Invited: 3 results)

  • [Journal Article] Tumor Targeting of 211At-Labeled Antibody under Sodium Ascorbate Protection against Radiolysis2023

    • Author(s)
      Takashima Hiroki、Ohnuki Kazunobu、Manabe Shino、Koga Yoshikatsu、Tsumura Ryo、Anzai Takahiro、Wang Yang、Yin Xiaojie、Sato Nozomi、Shigekawa Yudai、Nambu Akihiro、Usuda Sachiko、Haba Hiromitsu、Fujii Hirofumi、Yasunaga Masahiro
    • Journal Title

      Molecular Pharmaceutics

      Volume: 20 Issue: 2 Pages: 1156-1167

    • DOI

      10.1021/acs.molpharmaceut.2c00869

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Estimation of radiative half-life of 229mTh by half-life measurement of other nuclear excited states in 229Th2022

    • 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
    • Journal Title

      RIKEN Accel. Prog. Rep.

      Volume: 55

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Development of RF carpet gas cell for extracting 229mTh ions2022

    • Author(s)
      Y. Shigekawa, K. Tokoi, A. Yamaguchi, N. Sato, M. Wada, and H. Haba
    • Journal Title

      RIKEN Accel. Prog. Rep.

      Volume: 55 Pages: 127-127

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Development of a photon measurement apparatus for observing the radiative decay of 229mTh produced from 229Pa2022

    • Author(s)
      Y. Shigekawa, Y. Wang, X. Yin, A. Nambu, T. Yokokita, and H. Haba
    • Journal Title

      RIKEN Accel. Prog. Rep.

      Volume: 55 Pages: 124-124

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Surface ionization of protactinium toward implanting 229Pa into a CaF2 crystal2022

    • Author(s)
      Y. Shigekawa, and H. Haba
    • Journal Title

      RIKEN Accel. Prog. Rep.

      Volume: 55 Pages: 126-126

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Probing Optimal Reaction Energy for Synthesis of Element 119 from <sup>51</sup>V+<sup>248</sup>Cm Reaction with Quasielastic Barrier Distribution Measurement2022

    • Author(s)
      M. Tanaka and Y. Shigekawa (34人中29番目) et al.
    • Journal Title

      Journal of the Physical Society of Japan

      Volume: 91 Issue: 8 Pages: 084201-084201

    • DOI

      10.7566/jpsj.91.084201

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Coprecipitation with samarium hydroxide using multitracer produced through neutron-induced fission of 235U toward chemical study of heavy elements2022

    • Author(s)
      Kasamatsu Yoshitaka、Nagase Masahiro、Ninomiya Hidemi、Watanabe Eisuke、Shigekawa Yudai、Kondo Narumi、Takamiya Koichi、Ohtsuki Tsutomu、Shiohara Naoya、Shinohara Atsushi
    • Journal Title

      Applied Radiation and Isotopes

      Volume: 179 Pages: 110006-110006

    • DOI

      10.1016/j.apradiso.2021.110006

    • Related Report
      2022 Annual Research Report
    • Peer Reviewed / Open Access
  • [Journal Article] Estimation of radiative half-life of 229mTh by half-life measurement of other nuclear excited states in 229Th2021

    • Author(s)
      Shigekawa Y.、Yamaguchi A.、Suzuki K.、Haba H.、Hiraki T.、Kikunaga H.、Masuda T.、Nishimura S.、Sasao N.、Yoshimi A.、Yoshimura K.
    • Journal Title

      Physical Review C

      Volume: 104 Issue: 2 Pages: 024306-024306

    • DOI

      10.1103/physrevc.104.024306

    • Related Report
      2021 Research-status Report
    • Peer Reviewed
  • [Journal Article] Production and photon measurement of 229Pa toward the observation of radiative decay of 229mTh2021

    • Author(s)
      Y. Shigekawa, T. Yokokita, Y. Komori, and H. Haba
    • Journal Title

      RIKEN Accel. Prog. Rep.

      Volume: 54 Pages: 143-144

    • Related Report
      2021 Research-status Report
    • Peer Reviewed
  • [Journal Article] Measurement of Extraction Time and E&#64259;ciency of 220Rn Ions Using a Cryogenic RF-Carpet Gas Cell for the Chemistry of Superheavy Elements2021

    • Author(s)
      Y. Shigekawa, A. Yamaguchi, N. Sato, A. Takamine, M. Wada, and H. Haba
    • Journal Title

      RIKEN Accel. Prog. Rep.

      Volume: 54 Pages: 145-146

    • Related Report
      2021 Research-status Report
    • Peer Reviewed
  • [Journal Article] Anion- and cation-exchange studies of Zr, Hf, and Th using ion-exchange resin and fiber in H2SO4 media for chemical characterization of sulfate complex of Rf2021

    • Author(s)
      E. Watanabe, Y. Kasamatsu, T. Yokokita, S. Hayami, K. Tonai, H. Ninomiya, N. Kondo, Y. Shigekawa, H. Haba, Y. Kitagawa, M. Nakano, and A. Shinohara
    • Journal Title

      Solvent Extr. Ion Exch.

      Volume: 未定 Issue: 6 Pages: 1-16

    • DOI

      10.1080/07366299.2021.2020956

    • Related Report
      2021 Research-status Report
    • Peer Reviewed
  • [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
    • Journal Title

      NATURE CHEMISTRY

      Volume: 13 Issue: 3 Pages: 226-230

    • DOI

      10.1038/s41557-020-00634-6

    • Related Report
      2020 Research-status Report
    • Peer Reviewed
  • [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
    • Journal Title

      Journal of Synchrotron Radiation

      Volume: 28 Issue: 1 Pages: 111-119

    • DOI

      10.1107/s1600577520014526

    • NAID

      120006956810

    • Related Report
      2020 Research-status Report
    • Peer Reviewed / Open Access / Int'l Joint Research
  • [Journal Article] Development of a retarding-field type magnetic bottle spectrometer for studying the internal-conversion process of 235mU2020

    • Author(s)
      Shigekawa Y.、Kasamatsu Y.、Yamakita Y.、Yasuda Y.、Watanabe E.、Kondo N.、Haba H.、Shinohara A.
    • Journal Title

      Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment

      Volume: 976 Pages: 164207-164207

    • DOI

      10.1016/j.nima.2020.164207

    • Related Report
      2020 Research-status Report
    • Peer Reviewed
  • [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
    • Journal Title

      RIKEN Accel. Prog. Rep.

      Volume: 53 Pages: 51-51

    • Related Report
      2020 Research-status Report
    • Peer Reviewed
  • [Journal Article] Development of an RF-carpet gas cell for the chemistry of superheavy elements2020

    • Author(s)
      Y. Shigekawa, A. Yamaguchi, N. Sato, A. Takamine, M. Wada, and H. Haba
    • Journal Title

      RIKEN Accel. Prog. Rep.

      Volume: 53 Pages: 168-168

    • Related Report
      2020 Research-status Report
    • Peer Reviewed
  • [Journal Article] Solvent Extraction of Zr and Hf from HCl by Aliquat 336 using a Flow-Type Extraction Apparatus Toward Online Chemical Studies of Element 104, Rutherfordium2020

    • Author(s)
      Kasamatsu Yoshitaka、Kondo Narumi、Nakamura Kouhei、Kuboki Yuki、Ninomiya Hidemi、Shigekawa Yudai、Watanabe Eisuke、Yasuda Yuki、Toyomura Keigo、Nagase Masahiro、Yokokita Takuya、Komori Yukiko、Haba Hiromitsu、Yoshimura Takashi、Itabashi Hideyuki、Shinohara Atsushi
    • Journal Title

      Solvent Extraction and Ion Exchange

      Volume: 38 Issue: 3 Pages: 318-327

    • DOI

      10.1080/07366299.2020.1726075

    • Related Report
      2020 Research-status Report
    • Peer Reviewed
  • [Journal Article] Production of Bh266 in the Cm248(Na23,5n)Bh266 reaction and its decay properties2020

    • Author(s)
      Haba H.他(Shigekawa Y. 19番目)
    • Journal Title

      Physical Review C

      Volume: 102 Issue: 2 Pages: 024625-024625

    • DOI

      10.1103/physrevc.102.024625

    • Related Report
      2020 Research-status Report
    • Peer Reviewed / Int'l Joint Research
  • [Presentation] Progress toward observing γ-rays emitted from 229mTh by doping fluoride crystals with 229Pa2023

    • Author(s)
      Yudai Shigekawa, Wang Yang, Yin Xiaojie, Akihiro Nambu, Hiromitsu Haba
    • Organizer
      5th International Conference on Application of RadiotraCers and Energetic Beams in Sciences (ARCEBS 2023)
    • Related Report
      2022 Annual Research Report
    • Int'l Joint Research
  • [Presentation] トリウム229アイソマー状態からの脱励起真空紫外光の探索2023

    • Author(s)
      平木貴宏, Kjeld Beeks, 藤本弘之, 福永優太, 管明, 羽場宏光, 笠松良崇, 北尾真司, 小無健司, 増田孝彦, 永澤延元, 岡井晃一, 笹尾登, Fabian Schaden, Thorsten Schumm, 瀬戸誠, 重河優大, 高取沙悠理, 玉作賢治, 植竹智, 渡部司, 渡部信, 山口敦史, 安田勇輝, 依田芳卓, 吉見彰洋, 吉村浩司, 吉村太彦
    • Organizer
      日本物理学会2023年春季大会
    • Related Report
      2022 Annual Research Report
  • [Presentation] 固体原子核時計の実現へ向けた放射光X線を用いたトリウム229結晶の特性評価2023

    • Author(s)
      高取沙悠理, Kjeld Beeks, 藤本弘之, 福永優太, 管明, 羽場宏光, 平木貴宏, 笠松良崇, 北尾真司, 小無健司, 増田孝彦, 永澤延元, 岡井晃一, 笹尾登, Fabian Schaden, Thorsten Schumm, 瀬戸誠, 重河優大, 玉作賢治, 植竹智, 渡部司, 渡部信, 山口敦史, 安田勇輝, 依田芳卓, 吉見彰洋, 吉村浩司, 吉村太彦
    • Organizer
      日本物理学会2023年春季大会
    • Related Report
      2022 Annual Research Report
  • [Presentation] トリウム229アイソマー準位探索のための核共鳴散乱標的の開発2023

    • Author(s)
      福永優太, Kjeld Beeks, 藤本弘之, 平木貴宏, 管明, 羽場宏光, 笠松良崇, 北尾真司, 小無健司, 増田孝彦, 永澤延元, 岡井晃一, 笹尾登, Fabian Schaden, Thorsten Schumm, 瀬戸誠, 重河優大, 高取沙悠理, 玉作賢治, 植竹智, 渡部司, 渡部信, 山口敦史, 安田勇輝, 依田芳卓, 吉見彰洋, 吉村浩司, 吉村太彦
    • Organizer
      日本物理学会2023年春季大会
    • Related Report
      2022 Annual Research Report
  • [Presentation] 原子核時計実現にむけたトリウムイオンのトラップとレーザー分光2023

    • Author(s)
      山口敦史, 重河優大, 羽場宏光, 和田道治, 香取秀俊
    • Organizer
      レーザー学会学術講演会第43回年次大会
    • Related Report
      2022 Annual Research Report
    • Invited
  • [Presentation] 超低エネルギー励起核U-235mとTh-229mの核壊変特性に関する研究2022

    • Author(s)
      重河優大
    • Organizer
      電気学会2022年度第1回調査専門委員会
    • Related Report
      2022 Annual Research Report
    • Invited
  • [Presentation] Th-229mのγ線観測に向けたPa-229のフッ化物結晶への導入法及び光子測定装置の開発2022

    • Author(s)
      重河優大, Wang Yang, Yin Xiaojie, 南部明弘, 羽場宏光
    • Organizer
      日本放射化学会第66回討論会(2022)
    • Related Report
      2022 Annual Research Report
  • [Presentation] Laser spectroscopy of triply charged thorium ions towards a nuclear clock2022

    • Author(s)
      A. Yamaguchi, Y. Shigekawa, H. Haba, M. Wada, H. Katori
    • Organizer
      URSI-JRSM2022
    • Related Report
      2022 Annual Research Report
    • Int'l Joint Research / Invited
  • [Presentation] Development of an RF-carpet gas cell to obtain a low-energy thorium ion beam2022

    • Author(s)
      A. Yamaguchi, Y. Shigekawa, H. Haba, M. Wada, H. Katori
    • Organizer
      Second Workshop of the Center for Time, Constants and Fundamental Symmetries
    • Related Report
      2022 Annual Research Report
    • Int'l Joint Research
  • [Presentation] 229mThのγ線測定に向けた希ガスマトリックス単離装置の開発2022

    • Author(s)
      益田遼太郎, 安田勇輝, 澤村慶, 重河優大, 宮本祐樹, 吉村浩司, 篠原厚, 笠松 良崇
    • Organizer
      日本放射化学会第66回討論会(2022)
    • Related Report
      2022 Annual Research Report
  • [Presentation] トリウム229アイソマー状態からの脱励起に伴う真空紫外光の探索2022

    • Author(s)
      岡井晃一, Kjeld Beeks, 藤本弘之, 福永優太, 管明, 羽場宏光, 原秀明, 平木貴宏, 稲垣新, 小早川大貴, 笠松良崇, 北尾真司, 小無健司, 増田孝彦, 宮本祐樹, 笹尾登, Thorsten Schumm, 瀬戸誠, 重河優大, 高取沙悠理, 玉作賢治, 植竹智, 渡部司, 渡部信, 山口敦史, 安田勇輝, 依田芳卓, 吉見彰洋, 吉村浩司, 吉村太彦
    • Organizer
      日本物理学会 2022年秋季大会
    • Related Report
      2022 Annual Research Report
  • [Presentation] 原子核時計実現にむけたトリウムイオントラップ装置の開発2022

    • Author(s)
      山口敦史, 重河優大, 羽場宏光, 和田道治, 香取秀俊
    • Organizer
      日本物理学会2022年秋季大会
    • Related Report
      2022 Annual Research Report
  • [Presentation] Th-229mの壊変特性の解明に向けた高周波イオン収集・質量分離装置の開発2021

    • Author(s)
      重河優大, 床井健運, 山口敦史, Wang Yang, Yin Xiaojie, 南部明弘, 佐藤望, 和田道治, 羽場宏光
    • Organizer
      日本放射化学会第65回討論会(2021)
    • Related Report
      2021 Research-status Report
  • [Presentation] U-233のα-γ同時計数測定によるTh-229の原子核励起状態の半減期の決定2020

    • Author(s)
      重河優大, 山口敦史, 鈴木健太, 羽場宏光, 平木貴宏, 菊永英寿, 西村俊二, 笹尾登, 吉見彰洋, 吉村浩司
    • Organizer
      日本放射化学会第64回討論会(2020)
    • Related Report
      2020 Research-status Report
  • [Presentation] 核化学研究用高周波イオン収集システムの開発2020

    • Author(s)
      重河優大, 山口敦史, 佐藤望, 高峰愛子, 和田道治, 羽場宏光
    • Organizer
      日本放射化学会第64回討論会(2020)
    • Related Report
      2020 Research-status Report

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Published: 2020-04-28   Modified: 2024-01-30  

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