# Energy of the 229Th nuclear clock transition

@article{Seiferle2019EnergyOT,
title={Energy of the 229Th nuclear clock transition},
author={Benedict Seiferle and Lars von der Wense and Pavlo V. Bilous and Ines Amersdorffer and Christoph Lemell and Florian Libisch and Simon Stellmer and Thorsten Schumm and Christoph Emanuel D{\"u}llmann and Adriana P{\'a}lffy and Peter G. Thirolf},
journal={Nature},
year={2019},
volume={573},
pages={243-246}
}
• Published 10 May 2019
• Physics
• Nature
Owing to its low excitation energy and long radiative lifetime, the first excited isomeric state of thorium-229, 229mTh, can be optically controlled by a laser1,2 and is an ideal candidate for the creation of a nuclear optical clock3, which is expected to complement and outperform current electronic-shell-based atomic clocks4. A nuclear clock will have various applications—such as in relativistic geodesy5, dark matter research6 and the observation of potential temporal variations of fundamental…
88 Citations
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.
The thorium-229 low-energy isomer and the nuclear clock
• Physics
Nature Reviews Physics
• 2021
The 229Th nucleus has an isomeric state at an energy of about 8 eV above the ground state, several orders of magnitude lower than typical nuclear excitation energies. This has inspired the
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
Extending Our Knowledge about the 229Th Nuclear Isomer
• Physics, Chemistry
Atoms
• 2022
The first nuclear excited state in 229Th possesses the lowest excitation energy of all currently known nuclear levels. The energy difference between the ground- and first-excited (isomeric) state
Low-lying energy levels of 229Th35+ and the electronic bridge process
• Physics
• 2021
The nuclear transition between the ground and the low-energy isomeric state in the 229Th nucleus is of interest due to its high sensitivity to a hypothetical temporal variation of the fundamental
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
Energy of the ^{229}Th Nuclear Clock Isomer Determined by Absolute γ-ray Energy Difference.
• Physics
Physical review letters
• 2019
The low-lying isomeric state of ^{229}Th provides unique opportunities for high-resolution laser spectroscopy of the atomic nucleus and is determined by taking the absolute energy difference between the excitation energy required to populate the 29.2-keV state and the energy emitted in its decay to the isomersic excited state.
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
Detection of metastable electronic states by Penning trap mass spectrometry
• Physics
Nature
• 2020
The observation of a long-lived metastable electronic state in an HCI is reported by measuring the mass difference between the ground and excited states in rhenium, providing a non-destructive, direct determination of an electronic excitation energy.
The theory of direct laser excitation of nuclear transitions
• Physics
• 2020
A comprehensive theoretical study of direct laser excitation of a nuclear state based on the density matrix formalism is presented. The nuclear clock isomer $^{229\text{m}}$Th is discussed in detail,

## References

SHOWING 1-10 OF 62 REFERENCES
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.
Laser spectroscopic characterization of the nuclear-clock isomer 229mTh
• Physics
Nature
• 2018
The laser spectroscopic investigation of the hyperfine structure of the doubly charged 229mTh ion and the determination of the fundamental nuclear properties of the isomer, namely, its magnetic dipole and electric quadrupole moments, as well as its nuclear charge radius are presented.
Direct detection of the 229Th nuclear clock transition
• Physics
Nature
• 2016
The direct detection of this nuclear state of 229mTh is reported, which is further confirmation of the existence of the isomer and lays the foundation for precise studies of its decay parameters.
Towards a precise determination of the excitation energy of the Thorium nuclear isomer using a magnetic bottle spectrometer
• Physics
Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms
• 2020
Toward an energy measurement of the internal conversion electron in the deexcitation of the Th229 isomer
• Physics
Physical Review C
• 2018
The first excited isomeric state of Th-229 has an exceptionally low energy of only a few eV and could form the gateway to high-precision laser spectroscopy of nuclei. The excitation energy of the
Lifetime Measurement of the ^{229}Th Nuclear Isomer.
• Physics
Physical review letters
• 2017
The measurement of the internal-conversion decay half-life of neutral ^{229m}Th has been measured, which is in the range of theoretical predictions and gives further support for an internal conversion coefficient of ≈10^{9}, thus constraining the strength of a radiative branch in the presence of internal conversion.
Constraining the evolution of the fundamental constants with a solid-state optical frequency reference based on the 229Th nucleus.
• Physics
Physical review letters
• 2010
It is argued that the 229Th optical nuclear transition may be driven inside a host crystal with a high transition Q to allow for the construction of a solid-state optical frequency reference that surpasses the short-term stability of current optical clocks, as well as improved limits on the variability of fundamental constants.
Nuclear laser spectroscopy of the 3.5 eV transition in Th-229
• Physics
• 2003
We propose high-resolution laser spectroscopy of the 3.5 eV nuclear transition in Th-229 in isolated atoms. Laser excitation of the nucleus can be detected efficiently in a double-resonance method by
Prospects for measuring the 229Th isomer energy using a metallic magnetic microcalorimeter☆
• Physics
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment
• 2014
Energy splitting of the ground-state doublet in the nucleus 229Th.
• Physics
Physical review letters
• 2007
The energy splitting of the 229Th ground-state doublet is measured to be 7.6+/-0.5 eV, significantly greater than earlier measurements. Gamma rays produced following the alpha decay of 233U (105