X-ray pumping of the 229Th nuclear clock isomer

Takahiko Masuda, Akihiro Yoshimi, Akira Fujieda, Hiroyuki Fujimoto, Hiromitsu Haba, Hideaki Hara, Takahiro Hiraki, Hiroyuki Kaino, Yoshitaka Kasamatsu, Shinji Kitao, Kenji Konashi, Yuki Miyamoto, Koichi Okai, Sho Okubo, Noboru Sasao, Makoto Seto, Thorsten Schumm, Yudai Shigekawa, Kenta Suzuki, Simon StellmerKenji Tamasaku, Satoshi Uetake, Makoto Watanabe, Tsukasa Watanabe, Yuki Yasuda, Atsushi Yamaguchi, Yoshitaka Yoda, Takuya Yokokita, Motohiko Yoshimura, Koji Yoshimura

Research output: Contribution to journalLetter

3 Citations (Scopus)

Abstract

The metastable first excited state of thorium-229, 229mTh, is just a few electronvolts above the nuclear ground state1–4 and is accessible by vacuum ultraviolet lasers. The ability to manipulate the 229Th nuclear states with the precision of atomic laser spectroscopy5 opens up several prospects6, from studies of fundamental interactions in physics7,8 to applications such as a compact and robust nuclear clock5,9,10. However, direct optical excitation of the isomer and its radiative decay to the ground state have not yet been observed, and several key nuclear structure parameters—such as the exact energies and half-lives of the low-lying nuclear levels of 229Th—remain unknown11. Here we present active optical pumping into 229mTh, achieved using narrow-band 29-kiloelectronvolt synchrotron radiation to resonantly excite the second excited state of 229Th, which then decays predominantly into the isomer. We determine the resonance energy with an accuracy of 0.07 electronvolts, measure a half-life of 82.2 picoseconds and an excitation linewidth of 1.70 nanoelectronvolts, and extract the branching ratio of the second excited state into the ground and isomeric state. These measurements allow us to constrain the 229mTh isomer energy by combining them with γ-spectroscopy data collected over the past 40 years.

Original languageEnglish
Pages (from-to)238-242
Number of pages5
JournalNature
Volume573
Issue number7773
DOIs
Publication statusPublished - Sep 12 2019

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Lasers
X-Rays
Thorium
Synchrotrons
Vacuum
Half-Life
Spectrum Analysis
Radiation

ASJC Scopus subject areas

  • General

Cite this

X-ray pumping of the 229Th nuclear clock isomer. / Masuda, Takahiko; Yoshimi, Akihiro; Fujieda, Akira; Fujimoto, Hiroyuki; Haba, Hiromitsu; Hara, Hideaki; Hiraki, Takahiro; Kaino, Hiroyuki; Kasamatsu, Yoshitaka; Kitao, Shinji; Konashi, Kenji; Miyamoto, Yuki; Okai, Koichi; Okubo, Sho; Sasao, Noboru; Seto, Makoto; Schumm, Thorsten; Shigekawa, Yudai; Suzuki, Kenta; Stellmer, Simon; Tamasaku, Kenji; Uetake, Satoshi; Watanabe, Makoto; Watanabe, Tsukasa; Yasuda, Yuki; Yamaguchi, Atsushi; Yoda, Yoshitaka; Yokokita, Takuya; Yoshimura, Motohiko; Yoshimura, Koji.

In: Nature, Vol. 573, No. 7773, 12.09.2019, p. 238-242.

Research output: Contribution to journalLetter

Masuda, T, Yoshimi, A, Fujieda, A, Fujimoto, H, Haba, H, Hara, H, Hiraki, T, Kaino, H, Kasamatsu, Y, Kitao, S, Konashi, K, Miyamoto, Y, Okai, K, Okubo, S, Sasao, N, Seto, M, Schumm, T, Shigekawa, Y, Suzuki, K, Stellmer, S, Tamasaku, K, Uetake, S, Watanabe, M, Watanabe, T, Yasuda, Y, Yamaguchi, A, Yoda, Y, Yokokita, T, Yoshimura, M & Yoshimura, K 2019, 'X-ray pumping of the 229Th nuclear clock isomer', Nature, vol. 573, no. 7773, pp. 238-242. https://doi.org/10.1038/s41586-019-1542-3
Masuda, Takahiko ; Yoshimi, Akihiro ; Fujieda, Akira ; Fujimoto, Hiroyuki ; Haba, Hiromitsu ; Hara, Hideaki ; Hiraki, Takahiro ; Kaino, Hiroyuki ; Kasamatsu, Yoshitaka ; Kitao, Shinji ; Konashi, Kenji ; Miyamoto, Yuki ; Okai, Koichi ; Okubo, Sho ; Sasao, Noboru ; Seto, Makoto ; Schumm, Thorsten ; Shigekawa, Yudai ; Suzuki, Kenta ; Stellmer, Simon ; Tamasaku, Kenji ; Uetake, Satoshi ; Watanabe, Makoto ; Watanabe, Tsukasa ; Yasuda, Yuki ; Yamaguchi, Atsushi ; Yoda, Yoshitaka ; Yokokita, Takuya ; Yoshimura, Motohiko ; Yoshimura, Koji. / X-ray pumping of the 229Th nuclear clock isomer. In: Nature. 2019 ; Vol. 573, No. 7773. pp. 238-242.
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abstract = "The metastable first excited state of thorium-229, 229mTh, is just a few electronvolts above the nuclear ground state1–4 and is accessible by vacuum ultraviolet lasers. The ability to manipulate the 229Th nuclear states with the precision of atomic laser spectroscopy5 opens up several prospects6, from studies of fundamental interactions in physics7,8 to applications such as a compact and robust nuclear clock5,9,10. However, direct optical excitation of the isomer and its radiative decay to the ground state have not yet been observed, and several key nuclear structure parameters—such as the exact energies and half-lives of the low-lying nuclear levels of 229Th—remain unknown11. Here we present active optical pumping into 229mTh, achieved using narrow-band 29-kiloelectronvolt synchrotron radiation to resonantly excite the second excited state of 229Th, which then decays predominantly into the isomer. We determine the resonance energy with an accuracy of 0.07 electronvolts, measure a half-life of 82.2 picoseconds and an excitation linewidth of 1.70 nanoelectronvolts, and extract the branching ratio of the second excited state into the ground and isomeric state. These measurements allow us to constrain the 229mTh isomer energy by combining them with γ-spectroscopy data collected over the past 40 years.",
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T1 - X-ray pumping of the 229Th nuclear clock isomer

AU - Masuda, Takahiko

AU - Yoshimi, Akihiro

AU - Fujieda, Akira

AU - Fujimoto, Hiroyuki

AU - Haba, Hiromitsu

AU - Hara, Hideaki

AU - Hiraki, Takahiro

AU - Kaino, Hiroyuki

AU - Kasamatsu, Yoshitaka

AU - Kitao, Shinji

AU - Konashi, Kenji

AU - Miyamoto, Yuki

AU - Okai, Koichi

AU - Okubo, Sho

AU - Sasao, Noboru

AU - Seto, Makoto

AU - Schumm, Thorsten

AU - Shigekawa, Yudai

AU - Suzuki, Kenta

AU - Stellmer, Simon

AU - Tamasaku, Kenji

AU - Uetake, Satoshi

AU - Watanabe, Makoto

AU - Watanabe, Tsukasa

AU - Yasuda, Yuki

AU - Yamaguchi, Atsushi

AU - Yoda, Yoshitaka

AU - Yokokita, Takuya

AU - Yoshimura, Motohiko

AU - Yoshimura, Koji

PY - 2019/9/12

Y1 - 2019/9/12

N2 - The metastable first excited state of thorium-229, 229mTh, is just a few electronvolts above the nuclear ground state1–4 and is accessible by vacuum ultraviolet lasers. The ability to manipulate the 229Th nuclear states with the precision of atomic laser spectroscopy5 opens up several prospects6, from studies of fundamental interactions in physics7,8 to applications such as a compact and robust nuclear clock5,9,10. However, direct optical excitation of the isomer and its radiative decay to the ground state have not yet been observed, and several key nuclear structure parameters—such as the exact energies and half-lives of the low-lying nuclear levels of 229Th—remain unknown11. Here we present active optical pumping into 229mTh, achieved using narrow-band 29-kiloelectronvolt synchrotron radiation to resonantly excite the second excited state of 229Th, which then decays predominantly into the isomer. We determine the resonance energy with an accuracy of 0.07 electronvolts, measure a half-life of 82.2 picoseconds and an excitation linewidth of 1.70 nanoelectronvolts, and extract the branching ratio of the second excited state into the ground and isomeric state. These measurements allow us to constrain the 229mTh isomer energy by combining them with γ-spectroscopy data collected over the past 40 years.

AB - The metastable first excited state of thorium-229, 229mTh, is just a few electronvolts above the nuclear ground state1–4 and is accessible by vacuum ultraviolet lasers. The ability to manipulate the 229Th nuclear states with the precision of atomic laser spectroscopy5 opens up several prospects6, from studies of fundamental interactions in physics7,8 to applications such as a compact and robust nuclear clock5,9,10. However, direct optical excitation of the isomer and its radiative decay to the ground state have not yet been observed, and several key nuclear structure parameters—such as the exact energies and half-lives of the low-lying nuclear levels of 229Th—remain unknown11. Here we present active optical pumping into 229mTh, achieved using narrow-band 29-kiloelectronvolt synchrotron radiation to resonantly excite the second excited state of 229Th, which then decays predominantly into the isomer. We determine the resonance energy with an accuracy of 0.07 electronvolts, measure a half-life of 82.2 picoseconds and an excitation linewidth of 1.70 nanoelectronvolts, and extract the branching ratio of the second excited state into the ground and isomeric state. These measurements allow us to constrain the 229mTh isomer energy by combining them with γ-spectroscopy data collected over the past 40 years.

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