Radioactive Origin of Emissions Observed from Uranium Compounds and Their Silica Cells

Young, J. P.; Shaw, Robert W.; Webb, Oren F.

doi:10.1021/ic990558b

Cited by 15 publications

(10 citation statements)

References 9 publications

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“…By comparing the signal yields obtained for the photoelectric and the NRS interaction, one can deduce the excitation cross section for the cross-band nuclear excitation to the 29.19 keV state. Combined with the formerly known cross section for the in-band process [9,15], the 𝑏𝑏29 branching ratio could be extracted as 1/9.4 (24), in good agreement with the value measured in gamma spectroscopy. This branching ratio describes the radiative (gamma) decay of the 29.19 keV level, leading predominantly (90%) into the isomeric state (in-band transition).…”

Section: X-ray Pumping Nuclear Resonant Scatteringsupporting

confidence: 82%

Nuclear clocks for testing fundamental physics

Peik

Schumm

Safronova

et al. 2021

Quantum Sci. Technol.

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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 innovative ideas and studies that expand the understanding of atomic and nuclear structure of heavy elements and of the interaction of nuclei with bound electrons and coherent light. Using the nuclear resonance frequency, determined by the strong and electromagnetic interactions inside the nucleus, it is possible to build a highly precise nuclear clock that will be fundamentally different from all other atomic clocks based on resonant frequencies of the electron shell. The nuclear clock will open opportunities for highly sensitive tests of fundamental principles of physics, particularly in searches for violations of Einstein’s equivalence principle and for new particles and interactions beyond the standard model. It has been proposed to use the nuclear clock to search for variations of the electromagnetic and strong coupling constants and for dark matter searches. The 229Th nuclear optical clock still represents a major challenge in view of the tremendous gap of nearly 17 orders of magnitude between the present uncertainty in the nuclear transition frequency (about 0.2 eV, corresponding to ∼48 THz) and the natural linewidth (in the mHz range). Significant experimental progress has been achieved in recent years, which will be briefly reviewed. Moreover, a research strategy will be outlined to consolidate our present knowledge about essential 229mTh properties, to determine the nuclear transition frequency with laser spectroscopic precision, realize different types of nuclear clocks and apply them in precision frequency comparisons with optical atomic clocks to test fundamental physics. Two avenues will be discussed: laser-cooled trapped 229Th ions that allow experiments with complete control on the nucleus–electron interaction and minimal systematic frequency shifts, and Th-doped solids enabling experiments at high particle number and in different electronic environments.

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Section: X-ray Pumping Nuclear Resonant Scatteringsupporting

confidence: 82%

Nuclear clocks for testing fundamental physics

Peik

Schumm

Safronova

et al. 2021

Quantum Sci. Technol.

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“…In 1999, light emitted from 233 U samples was unambiguously shown to originate from α-particle induced fluorescence of nitrogen [325,389] and from luminescence of the uranyl ion [416]. Therefore the direct detection of 229m Th remained an open question [145].…”

Section: Population Via a Natural Decay Branchmentioning

confidence: 99%

The $$^{229}$$Th isomer: prospects for a nuclear optical clock

Wense

2020

Eur. Phys. J. A

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The proposal for the development of a nuclear optical clock has triggered a multitude of experimental and theoretical studies. In particular the prediction of an unprecedented systematic frequency uncertainty of about $$10^{-19}$$ 10 - 19 has rendered a nuclear clock an interesting tool for many applications, potentially even for a re-definition of the second. The focus of the corresponding research is a nuclear transition of the $$^{229}$$ 229 Th nucleus, which possesses a uniquely low nuclear excitation energy of only $$8.12\pm 0.11$$ 8.12 ± 0.11 eV ($$152.7\pm 2.1$$ 152.7 ± 2.1 nm). This energy is sufficiently low to allow for nuclear laser spectroscopy, an inherent requirement for a nuclear clock. Recently, some significant progress toward the development of a nuclear frequency standard has been made and by today there is no doubt that a nuclear clock will become reality, most likely not even in the too far future. Here we present a comprehensive review of the current status of nuclear clock development with the objective of providing a rather complete list of literature related to the topic, which could serve as a reference for future investigations.

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“…Fluorescence experiments with radioactive samples and ultraviolet light sources may be severely affected by thermoluminescence, Cherenkov radiation etc. [13,14]. All further attempts at a direct observation of the optical transition connecting ground state and isomer failed.…”

Section: The Low-lying Isomer Of 229 Thmentioning

confidence: 99%

Prospects for a Nuclear Optical Frequency Standard Based on Thorium-229

Peik¹,

Zimmermann²,

Okhapkin³

et al. 2009

Frequency Standards and Metrology

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The 7.6-eV-isomer of Thorium-229 offers the opportunity to perform high resolution laser spectroscopy of a nuclear transition. We give a brief review of the investigations of this isomer. The nuclear resonance connecting ground state and isomer may be used as the reference of an optical clock of very high accuracy using trapped and laser-cooled thorium ions, or in a compact solid-state optical frequency standard of high stability.

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Radioactive Origin of Emissions Observed from Uranium Compounds and Their Silica Cells

Cited by 15 publications

References 9 publications

Nuclear clocks for testing fundamental physics

Nuclear clocks for testing fundamental physics

The $$^{229}$$Th isomer: prospects for a nuclear optical clock

Prospects for a Nuclear Optical Frequency Standard Based on Thorium-229

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