Attempt to optically excite the nuclear isomer in 
<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mmultiscripts><mml:mi>Th</mml:mi><mml:mprescripts /><mml:none /><mml:mn>229</mml:mn></mml:mmultiscripts></mml:math>

Stellmer, Simon; Kazakov, G.; Schreitl, Matthias; Kaser, Hendrik; Kolbe, Michael; Schumm, Thorsten

doi:10.1103/physreva.97.062506

Cited by 54 publications

(51 citation statements)

References 42 publications

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“…All investigations mentioned above utilize α-decay of 233 U to produce 229m Th. Several experiments attempted a direct optical excitation with broad band ∼ 7.8 eV synchrotron radiation [12][13][14] ; all showed null results, suggesting that E is or its half-life might lie outside the commonly ex-pected range.…”

Section: Introductionmentioning

confidence: 99%

X-ray pumping of the 229Th nuclear clock isomer

Masuda

Yoshimi

Fujieda

et al. 2019

Nature

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Thorium-229 is a unique case in nuclear physics: it presents a metastable first excited state 229m Th, just a few electronvolts above the nuclear ground state. This so-called isomer is accessible by VUV lasers, which allows transferring the amazing precision of atomic laser spectroscopy to nuclear physics. Being able to manipulate the 229 Th nuclear states at will opens up a multitude of prospects, from studies of the fundamental interactions in physics to applications as a compact and robust nuclear clock. However, direct optical excitation of the isomer or its radiative decay back to the ground state has not yet been observed, and a series of key nuclear structure parameters such as the exact energies and half-lives of the low-lying nuclear levels of 229 Th are yet unknown. Here we present the first active optical pumping into 229m Th. Our scheme employs narrow-band 29 keV synchrotron radiation to resonantly excite the second excited state, which then predominantly decays into the isomer. We determine the resonance energy with 0.07 eV accuracy, measure a half-life of 82.2 ps, an excitation linewidth of 1.70 neV, and extract the branching ratio of the second excited state into the ground and isomeric state respectively. These measurements allow us to re-evaluate gamma spectroscopy data that have been collected over 40 years.

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Section: Introductionmentioning

confidence: 99%

X-ray pumping of the 229Th nuclear clock isomer

Masuda

Yoshimi

Fujieda

et al. 2019

Nature

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“…[96][97][98] Progress beyond the direct identification of the isomer's existence and decay via internal conversion (in an experimental approach that was not designed to perform conversion electron spectroscopy, thus resulting only in a coarse constraint of the isomeric excitation energy between the first and third ionization potential of thorium, i.e., 6.3-18.3 eV)-could be achieved by measuring the lifetime of the neutral thorium isomer 229m Th. Despite the conceptual elegancy of this approach and in-tense experimental efforts conducted in various groups toward detecting the VUV fluorescence from 229 Th-doped crystals, so far none of these studies was able to provide conclusive results.…”

Section: Experimental Efforts Toward Exciting the 229m Th Isomermentioning

confidence: 99%

Improving Our Knowledge on the ^229mThorium Isomer: Toward a Test Bench for Time Variations of Fundamental Constants

Thirolf

Wense

2019

Annalen der Physik

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For more than four decades, the lowest excitation in the whole landscape of atomic nuclei, the low-lying, isomeric state of 229 Th, the so-called thorium isomer, has challenged physicists of various disciplines. Being a solitaire with its uniquely low excitation energy of <10 eV, its predicted lifetime of a few hours results in an extremely sharp relative linewidth E/E as low as 10 -20 . While until recently the indication of its existence was based only on indirect evidence, its unique properties inspired a multitude of potential applications, like the use of the thorium isomer as a nuclear frequency standard, potentially able to outperform even the best atomic clocks and a sensitivity-enhanced access to potential temporal variations of fundamental constants. The various proposals to exploit the unique properties of 229m Th are presented herein, in particular focusing on its ability to serve as a test bench for time variations of fundamental constants like the fine structure constant.

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“…The polarization of the emitted radiation is linear horizontal to a high degree (Neumann et al, 2014). Besides the monochromator beamline described in this work, the undulator radiation can be used in a direct as well as a 10deflected beamline branch for measurements without need for further monochromatization beyond the natural undulator linewidth (Stellmer et al, 2018).…”

Section: Undulator Source Parametersmentioning

confidence: 99%

The U125 insertion device beamline at the Metrology Light Source

Gottwald

Kaser

Kolbe

2019

J Synchrotron Radiat

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At the Metrology Light Source, an electron storage ring dedicated to metrological applications, the U125 insertion device beamline utilizes undulator radiation for various applications over a broad spectral range. Using a hybrid normal-incidence and grazing-incidence in-vacuum switchable plane-grating monochromator, a spectral region ranging from the near-infrared to soft X-ray is covered. The beamline is dedicated to surface-analytical methods, e.g. ellipsometry, photoelectron spectroscopy or photoemission tomography. The traceability of radiometric quantities, i.e. quantitative determination of the available radiant power (or photon flux), is required for some of these applications to support the metrological aspect of the measurements. In particular, attention is paid to the suppression of unwanted spectral contributions from higher diffraction orders, and to the monitoring of the radiation intensity during the measurements. With the results from the beamline commissioning, an uncertainty budget for all relevant radiometric quantities was established. beamlines J. Synchrotron Rad. (2019). 26, 535-542 Alexander Gottwald et al. The U125 insertion device beamline 537

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Attempt to optically excite the nuclear isomer in Th229

Cited by 54 publications

References 42 publications

X-ray pumping of the 229Th nuclear clock isomer

X-ray pumping of the 229Th nuclear clock isomer

Improving Our Knowledge on the ^229mThorium Isomer: Toward a Test Bench for Time Variations of Fundamental Constants

The U125 insertion device beamline at the Metrology Light Source

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Attempt to optically excite the nuclear isomer in Th229

Cited by 54 publications

References 42 publications

X-ray pumping of the 229Th nuclear clock isomer

X-ray pumping of the 229Th nuclear clock isomer

Improving Our Knowledge on the 229mThorium Isomer: Toward a Test Bench for Time Variations of Fundamental Constants

The U125 insertion device beamline at the Metrology Light Source

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Improving Our Knowledge on the ^229mThorium Isomer: Toward a Test Bench for Time Variations of Fundamental Constants