# X-ray pumping of the 229Th nuclear clock isomer

@article{Masuda2019XrayPO,
title={X-ray pumping of the 229Th nuclear clock isomer},
author={Takahiko Masuda and Akihiro Yoshimi and Akira Fujieda and Hiroyuki Fujimoto and Hiromitsu Haba and Hideaki Hara and Takahiro Hiraki and Hiroyuki Kaino and Yoshitaka Kasamatsu and Shinji Kitao and Kenji Konashi and Yuki Miyamoto and Koichi Okai and S. Okubo and Noboru Sasao and Makoto Seto and Thorsten Schumm and Yudai Shigekawa and Kenta Suzuki and Simon Stellmer and Kenji Tamasaku and Satoshi Uetake and Makoto Watanabe and Tsukasa Watanabe and Yuki Yasuda and Atsushi Yamaguchi and Yoshitaka Yoda and Takuya Yokokita and Motohiko Yoshimura and Koji Yoshimura},
journal={Nature},
year={2019},
volume={573},
pages={238-242}
}
• Published 13 February 2019
• Physics
• Nature
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…
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
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.
DFT calculation of 229thorium-doped magnesium fluoride for nuclear laser spectroscopy
• Physics, Materials Science
Journal of physics. Condensed matter : an Institute of Physics journal
• 2020
Using the Vienna Ab-initio Simulation Package (VASP), density functional theory (DFT) calculations of the electronic and optical properties of Th:MgF2 determine whether Thorium will be accepted as a dopant and identify the charge compensation mechanism and geometry, and indicate, that the band gap of Th-doped M gF2 will be significantly reduced compared to undoped Mgf2, below the expected229Th isomer energy.
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
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,
Measurement of the ^{229}Th Isomer Energy with a Magnetic Microcalorimeter.
• Physics
Physical review letters
• 2020
A measurement of the low-energy (0-60 keV) γ-ray spectrum produced in the α decay of ^{233}U using a dedicated cryogenic magnetic microcalorimeter and four complementary evaluation schemes is presented.
Estimation of radiative half-life of Th229m by half-life measurement of other nuclear excited states in Th229
• Physics
Physical Review C
• 2021
We perform coincidence measurements between α particles and γ rays from a U source to determine the half-lives of the excited state in a Th nucleus. We first prove that the half-lives of 42.43and
Development of a recoil ion source providing slow Th ions including 229(m)Th in a broad charge state distribution
• Physics
Hyperfine Interactions
• 2020
Ions of the isomer 229mTh are a topic of high interest for the construction of a “nuclear clock” and in the field of fundamental physics for testing symmetries of nature. They can be efficiently

## References

SHOWING 1-10 OF 56 REFERENCES
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.
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.
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
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
Nuclear resonant scattering experiment with fast time response: Photonuclear excitation of 201 Hg
• Physics
• 2018
Nuclear resonant excitation of the 29.19-keV level in $^{229}$Th with high-brilliance synchrotron- radiation and detection of its decay signal, are proposed with the aim of populating the extremely
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.
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
Experimental search for the low-energy nuclear transition in 229Th with undulator radiation
• Physics, Chemistry
• 2015
To search for the lowest energy nuclear isomeric transition in 229Th in solid samples, a novel adsorption technique which prepares 229Th atoms on a surface of CaF2 is developed. Adsorbed 229Th is
Attempt to optically excite the nuclear isomer in Th229
• Physics
Physical Review A
• 2018
We aim to perform direct optical spectroscopy of the $^{229}\mathrm{Th}$ nuclear isomer to measure its energy and lifetime, and to demonstrate optical coupling to the nucleus. To this end, we develop