The ²²⁹Th isomer: prospects for a nuclear optical clock

2020/09/30 by Lars von der Wense, Benedict Seiferle
Mathematics · Physics and Astronomy · #Advanced Frequency and Time Standards #Energy (signal processing) #Focus (optics) #Nuclear data #Nuclear reaction #Nuclear technology #Radioactive Decay and Measurement Techniques #Statistical and numerical algorithms #nucl-ex #physics.atom-ph

paper · pdf · doi:10.1140/epja/s10050-020-00263-0

published as Eur. Phys. J. A (2020) 56:277

openalex created_date 2020/10/08 · openalex publication_date 2020/11/01 · arxiv created 2020/11/07 · arxiv updated 2020/11/10 · openalex updated_date 2026/08/05

Abstract

Abstract 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mn>10</mml:mn><mml:mrow><mml:mo>-</mml:mo><mml:mn>19</mml:mn></mml:mrow></mml:msup></mml:math> 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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msup><mml:mrow/><mml:mn>229</mml:mn></mml:msup></mml:math> Th nucleus, which possesses a uniquely low nuclear excitation energy of only 8.12± 0.11 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>8.12</mml:mn><mml:mo>±</mml:mo><mml:mn>0.11</mml:mn></mml:mrow></mml:math> eV ( 152.7± 2.1 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>152.7</mml:mn><mml:mo>±</mml:mo><mml:mn>2.1</mml:mn></mml:mrow></mml:math> 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.

Citations

• The fundamental constants and their variation: observational and theoretical status
• Experimental search for the low-energy nuclear transition in229Th with undulator radiation
• Observation of an unexpected negative isotope shift inTh<mml:none/>+<mml:mprescripts/><mml:none/>229and its theoretical explanation
• Laser ablation loading of a radiofrequency ion trap
• Exponential Increase of Energy Level Density in Atoms: Th and Th II
• Energy Splitting of the Ground-State Doublet in the NucleusTh<mml:mprescripts/><mml:none/>229
• Frequency Ratio of Al+and Hg+Single-Ion Optical Clocks; Metrology at the 17th Decimal Place
• Nuclear laser spectroscopy of the 3.5 eV transition in Th-229
• Energy levels of Th<mml:mrow/>+between 7.3 and 8.3 eV
• Nuclear structure of 229Th
• The Evolution of the Quartz Crystal Clock*
• Towards a direct transition energy measurement of the lowest nuclear excitation in229Th
• Resonance ionization spectroscopy of thorium isotopes–towards a laser spectroscopic identification of the low-lying 7.6 eV isomer of229Th
• Impact of the electron environment on the lifetime of the229Thmlow-lying isomer
• Features of the low-energy level scheme of 229Th as observed in the α-decay of 233U
• Single-Ion Nuclear Clock for Metrology at the 19th Decimal Place
• Observation of the Deexcitation of theTh<mml:mprescripts/><mml:none/>229mNuclear Isomer
• Energy separation of the doublet of intrinsic states at the ground state ofTh<mml:mprescripts/>229
• Superconducting nanowire single-photon detectors: physics and applications
• An Atomic Standard of Frequency and Time Interval: A Cæsium Resonator
• Nuclear excitation by electron capture followed by fast x-ray emission
• Processes of the nuclear isomer 229mTh(3/2+, 3.5 ± 1.0 eV) resonant excitation by optical photons
• Radiative lifetime and energy of the low-energy isomeric level inTh<mml:mprescripts/><mml:none/>229
• Direct detection of the 229Th nuclear clock transition
• Gravitational wave detection with optical lattice atomic clocks
• An excited state ofTh<mml:mprescripts/>229at 3.5 eV
• Lifetime measurement of the ²²⁹Th nuclear isomer
• Reduced transition probabilities for the gamma decay of the 7.8 eV isomer in ²²⁹Th
• Effect of atomic electrons on the7.6-eV nuclear transition inTh<mml:mprescripts/><mml:none/>2293+
• Laser-induced electronic bridge for characterization of the229mTh → 229gTh nuclear transition with a tunable optical laser
• Laser spectroscopic characterization of the nuclear clock isomer ^229mTh
• A Laser Excitation Scheme for Th<mml:mprescripts/><mml:none/>229m
• Search for New Physics with Atoms and Molecules
• Attempt to optically excite the nuclear isomer in Th<mml:mprescripts/><mml:none/>229
• Collective effects in Th<mml:mprescripts/><mml:none/>229-doped crystals
• X-ray pumping of the Th-229 nuclear clock isomer
• JILA SrI Optical Lattice Clock with Uncertainty of 2.0 × 10^-18
• The 229-thorium isomer: doorway to the road from the atomic clock to the nuclear clock
• Results of a Direct Search Using Synchrotron Radiation for the Low-EnergyTh<mml:mprescripts/><mml:none/>229Nuclear Isomeric Transition
• 1.5 μm lasers with sub 10 mHz linewidth
• Towards a 229Th-based nuclear clock
• Energy of the ²²⁹Th nuclear clock transition
• Measurement of the ²²⁹Th isomer energy with a magnetic micro-calorimeter