# Direct detection of the 229Th nuclear clock transition

@article{Wense2016DirectDO,
title={Direct detection of the 229Th nuclear clock transition},
author={Lars von der Wense and Benedict Seiferle and Mustapha Laatiaoui and J{\"u}rgen B. Neumayr and Hans-J{\"o}rg Maier and H-F. Wirth and Ch. Mokry and J{\"o}rg Runke and Klaus Eberhardt and Christoph Emanuel D{\"u}llmann and Norbert Trautmann and Peter G. Thirolf},
journal={Nature},
year={2016},
volume={533},
pages={47-51}
}
• Published 5 May 2016
• Physics
• Nature
Today’s most precise time and frequency measurements are performed with optical atomic clocks. However, it has been proposed that they could potentially be outperformed by a nuclear clock, which employs a nuclear transition instead of an atomic shell transition. There is only one known nuclear state that could serve as a nuclear clock using currently available technology, namely, the isomeric first excited state of 229Th (denoted 229mTh). Here we report the direct detection of this nuclear…
Energy of the 229Th nuclear clock transition
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Nature
• 2019
The method combines nuclear and atomic physics measurements to advance precision metrology, and the findings are expected to facilitate the application of high-resolution laser spectroscopy on nuclei and to enable the development of a nuclear optical clock of unprecedented accuracy.
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Direct detection of the thorium-229 nuclear-clock transition is achieved, placing new limits on the transition energy and measuring the state's half-life, and these results suggest that nuclear quantum optics and nuclear lasers based on this transition may be plausible possibilities.
Direct Search for Low Energy Nuclear Isomeric Transition of Th-229m With TES Detector
• Physics
IEEE Transactions on Applied Superconductivity
• 2021
Precise knowledge of the energy and lifetime of 229mTh isomeric state has notable importance as a basis for a nuclear clock. Such a clock would be capable to extend precision on the oscillator
The 229-thorium isomer: doorway to the road from the atomic clock to the nuclear clock
• Physics
Journal of Physics B: Atomic, Molecular and Optical Physics
• 2019
The elusive ‘thorium isomer’, i.e. the isomeric first excited state of 229Th, has puzzled the nuclear and fundamental physics communities for more than 40 years. With an exceptionally low excitation
Charge exchange of 229(m)Th ions in carbon foils
The most precise time measurements at present are achieved with atomic clocks. However, it has been proposed that they could be outperformed by nuclear clocks, using a nuclear transition instead of
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• Physics
2017 Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFC)
• 2017
Recently, the first direct detection of the long-searched low-lying isomeric first excited state of 229Th could be realized via its internal conversion decay branch, which confirms the isomer's
X-ray pumping of the 229Th nuclear clock isomer
• Physics
Nature
• 2019
Active optical pumping is presented using narrow-band 29-kiloelectronvolt synchrotron radiation to resonantly excite the second excited state of 229Th, which then decays predominantly into the isomer, enabling accurate determination of the 229mTh isomer’s energy, half-life and excitation linewidth.
Nuclear clocks for testing fundamental physics
• Physics
Quantum Science and Technology
• 2021
The low-energy, long-lived isomer in 229Th, first studied in the 1970s as an exotic feature in nuclear physics, continues to inspire a multidisciplinary community of physicists. It has stimulated
Concepts for direct frequency-comb spectroscopy of 229mTh and an internal-conversion-based solid-state nuclear clock
• Physics
• 2020
A new concept for narrow-band direct nuclear laser spectroscopy of 229m Th is proposed, using a single comb mode of a vacuum ultraviolet frequency comb generated from the 7th harmonic of an Yb-doped
Alternative approach to populate and study the Th229 nuclear clock isomer
• Physics
Physical Review C
• 2019
A new approach to observe the radiative decay of the $^{229}$Th nuclear isomer, and to determine its energy and radiative lifetime, is presented. Situated at a uniquely low excitation energy, this

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