Direct detection of the 229Th nuclear clock transition

Wense, Lars von der; Seiferle, Benedict; Laatiaoui, M.; Neumayr, J. B.; Maier, H.; Wirth, H.‐F.; Mokry, C.; Runke, J.; Eberhardt, Κ.; Düllmann, Ch. E.; Trautmann, Ν.; Thirolf, P. G.

doi:10.1038/nature17669

Cited by 238 publications

(208 citation statements)

References 58 publications

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“…This low-energy isomeric state has attracted considerable attention a) Electronic mail: yoshimi@okayama-u.ac.jp not only from the perspective of nuclear and atomic physics but also because of applications to other research fields 1,2 . An important characteristic of 229m Th is that it is the only excited nuclear level that is optically accessible among known isotopes.…”

Section: Introductionmentioning

confidence: 99%

Nuclear resonant scattering experiment with fast time response: Photonuclear excitation of Hg201

Yoshimi¹,

Hara²,

Hiraki³

et al. 2018

Phys. Rev. C

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Nuclear resonant excitation of the 29.19-keV level in229 Th with high-brilliance synchrotron-radiation and detection of its decay signal, are proposed with the aim of populating the extremely low-energy isomeric state of 229 Th. The proposed experiment, known as nuclear resonant scattering (NRS), has the merit of being free from uncertainties about the isomer level energy. However, it requires higher time resolution and shorter tail in the response function of the detector than that of conventional NRS experiments because of the short lifetime of the 29.19-keV state. We have fabricated an X-ray detector system which has a time resolution of 56 ps and a shorter tail function than the previously reported one. We have demonstrated an NRS experiment with the 26.27-keV nuclear level of 201 Hg for feasibility assessment of the 229 Th experiment. The NRS signal is clearly distinct from the prompt electronic scattering signal by the implemented detector system. The half-life of the 26.27-keV state of 201 Hg is determined as 629 ± 18 ps which is better precision by a factor three than that reported to date.

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Section: Introductionmentioning

confidence: 99%

Nuclear resonant scattering experiment with fast time response: Photonuclear excitation of Hg201

Yoshimi¹,

Hara²,

Hiraki³

et al. 2018

Phys. Rev. C

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“…During IC decay, the nuclear excitation energy is transferred to the atomic shell, leading to the ejection of a shell electron. The IC decay channel of 229m Th has recently been experimentally observed [19,20] and is known to be the dominant decay channel under the considered experimental conditions. This approach corresponds to laser-based conversion electron Mössbauer spectroscopy (CEMS) in the optical region [21] and is found to be advantageous compared to earlier proposals that make use of a potential radiative decay for isomer detection.…”

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confidence: 99%

A Laser Excitation Scheme for Th229m

et al. 2017

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Direct laser excitation of the lowest known nuclear excited state in 229 Th has been a longstanding objective. It is generally assumed that reaching this goal would require a considerably reduced uncertainty of the isomer's excitation energy compared to the presently adopted value of (7.8 ± 0.5) eV. Here we present a direct laser excitation scheme for 229m Th, which circumvents this requirement. The proposed excitation scheme makes use of already existing laser technology and therefore paves the way for nuclear laser spectroscopy. In this concept, the recently experimentally observed internal-conversion decay channel of the isomeric state is used for probing the isomeric population. A signal-to-background ratio of better than 10 4 and a total measurement time of less than three days for laser scanning appear to be achievable.Direct nuclear laser excitation has come closer into reach within the past years, partly due to the development of free-electron-laser technology. Such ideas are typically dealing with the excitation of nuclear states in the energy range of at least a few keV or above [1,2]. However, there is one exceptional nuclear state known for the last 40 years with a significantly lower energy of presumably below 10 eV [3,4]. An excitation energy of (7.8 ± 0.5) eV, corresponding to (159 ± 11) nm wavelength or ∼ 1900 THz, is by today the most accepted value for the isomeric first excited state of 229 Th [5,6]. This state conceptionally allows for direct nuclear laser excitation using solid-state laser technology and was proposed for the development of a nuclear clock of extremely high stability, due to an expected high resilience against external influences and a radiative lifetime in the range of minutes to hours [7][8][9][10]. It is generally assumed that direct nuclear laser excitation of 229m Th requires a considerably improved knowledge of the isomeric transition energy (see e.g. Ref.[11] and references therein). The reasons are that, first, the present uncertainty in the knowledge of the isomeric energy value is still rather large. The currently best energy value of 7.8±0.5 eV leads to an energy range of at least 1 eV (corresponding to 2.4·1014 Hz) to be scanned when searching for the isomeric excitation. Second, the radiative lifetime of 229m Th was theoretically predicted to be in the range of hours [12][13][14], leading to long required detection times when searching for a radiative decay channel. This has led to the assumption that the required time for laserbased scanning of the large energy range of 1 eV would be prohibitively long. In order to shorten the required scanning times, there are worldwide efforts ongoing to decrease the uncertainty of the transition energy, which would bring the isomeric state into realistic reach of direct laser excitation (see e.g. Refs. [15-18]). A recent review is found in Ref. [11].Here we propose a different approach, which allows for a direct laser excitation of 229m Th without the requirement of an improved knowledge of the transition energy. As the requi...

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“…Three excellent experiments, Refs. [1,4,16], which gave us the knowledge on the existence of the low-lying isomeric state and provided with estimations of its energy, demonstrate the variety of experimental methods needed for the characterization of this state. The experimental technique gradually evolves from traditional methods of nuclear spectroscopy [1,3,4] to those used in low energy physics: solid state physics, optics, etc.…”

Section: Introductionmentioning

confidence: 99%

“…The experimental technique gradually evolves from traditional methods of nuclear spectroscopy [1,3,4] to those used in low energy physics: solid state physics, optics, etc. [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

“…The low lying 3/2 + (7.8 ± 0.5 eV) state [1,2] of the 229 Th nucleus has been the subject of intense experimental [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] and theoretical research [17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34] in the past decades. The interest is caused by new possibilities which are emerging in the study of such unusual nuclear level.…”

Section: Introductionmentioning

confidence: 99%

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Magnetic hyperfine structure of the ground-state doublet in highly charged ionsTh89+,87+229and the Bohr-Weisskopf effect

Tkalya

Николаев

2016

Phys. Rev. C

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Magnetic hyperfine structure of the ground-state doublet in highly charged ions 229 The magnetic hyperfine (MHF) structure of the 5/2 + (0.0 eV) ground state and the low-lying 3/2 + (7.8 eV) isomeric state of the 229 Th nucleus in highly charged ions Th 89+ and Th 87+ is calculated. The distribution of the nuclear magnetization (the Bohr-Weisskopf effect) is accounted for in the framework of the collective nuclear model with the wave functions of the Nilsson model for the unpaired neutron. The deviations of the MHF structure for the ground and isomeric states from their values in the model of point-like nuclear magnetic dipole are calculated. The influence of the mixing of the states with the same quantum number F on the energy of sublevels is studied. Taking into account the mixing of states, the probabilities of the transitions between the components of MHF structure are found.

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Direct detection of the 229Th nuclear clock transition

Cited by 238 publications

References 58 publications

Nuclear resonant scattering experiment with fast time response: Photonuclear excitation of Hg201

Nuclear resonant scattering experiment with fast time response: Photonuclear excitation of Hg201

A Laser Excitation Scheme for Th229m

Magnetic hyperfine structure of the ground-state doublet in highly charged ionsTh89+,87+229and the Bohr-Weisskopf effect

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