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

Abstract

Thorium-229 is a unique case in nuclear physics: it presents a metastable first excited state Th-229m, 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 Th-229 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 Th-229 are yet unknown. Here we present the first active optical pumping into Th-229m. 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.

14 pages with 9 figures and 3 tables

References in corpus (21)

• A Single-Ion Nuclear Clock for Metrology at the 19th Decimal Place
• Direct detection of the 229Th nuclear clock transition
• Enhanced effect of temporal variation of the fine structure constant in diatomic molecules
• Real-time geopotentiometry with synchronously linked optical lattice clocks
• Energy of the ${}^{229}$Th nuclear clock transition
• Laser spectroscopic characterization of the nuclear clock isomer ${}^{229m}$Th
• Performance of a 229 Thorium solid-state nuclear clock
• Lifetime measurement of the ${}^{229}$Th nuclear isomer
• A proposed experimental method to determine $\alpha$-sensitivity of splitting between ground and 7.6 eV isomeric states in Th-229
• Nuclear clocks based on resonant excitation of gamma-transitions
• Radiative lifetime and energy of the low-energy isomeric level in ${}^{229}$Th
• Lasers as a Bridge between Atomic and Nuclear Physics
• Enhanced violation of the Lorentz invariance and Einstein's equivalence principle in nuclei and atoms
• On an attempt to optically excite the nuclear isomer in Th-229
• Sensitivity of Nuclear Transition Frequencies to Temporal Variation of the Fine Structure Constant or the Strong Interaction
• Prospects for measuring the 229Th isomer energy using a metallic magnetic microcalorimeter
• Enhanced effect of temporal variation of the fine structure constant and strong interaction in 229Th
• Fast X-ray detector system with simultaneous measurement of timing and energy for a single photon
• Nuclear resonant scattering experiment with fast time response: new scheme for observation of ${}^{229\mathrm{m}}$Th radiative decay
• Results of a direct search using synchrotron radiation for the low-energy ${}^{229}$Th nuclear isomeric transition
• Energy response of X-rays under high flux conditions using a thin APD for the energy range of 6-33 keV

Cited by in corpus (34)

• Energy of the ${}^{229}$Th nuclear clock transition
• Frequency ratio of the ${}^{229\mathrm{m}}$Th nuclear isomeric transition and the ${}^{87}$Sr atomic clock
• Observation of the radiative decay of the ${}^{229}\mathrm{Th}$ nuclear clock isomer
• Measurement of the ${}^{229}$Th isomer energy with a magnetic micro-calorimeter
• Opportunities for Fundamental Physics Research with Radioactive Molecules
• Sensitivity of ${}^{229}$Th nuclear clock transition to variation of the fine-structure constant
• Energy of the ${}^{229}$Th Nuclear Clock Isomer Determined by Absolute $\gamma$-ray Energy Difference
• Atlas of Nuclear Isomers -- Second Edition
• Electronic bridge excitation in highly charged Th-229 ions
• The ${}^{229}$Th isomer: prospects for a nuclear optical clock
• Expanding Nuclear Physics Horizons with the Gamma Factory
• Recent progress in laser spectroscopy of the actinides
• Atomic, molecular and optical physics applications of longitudinally coherent and narrow bandwidth Free-Electron Lasers
• Controlling ${}^{229}$Th isomeric state population in a VUV transparent crystal
• Concepts for direct frequency-comb spectroscopy of ${}^{229\text{m}}$Th and an internal-conversion-based solid-state nuclear clock
• The theory of direct laser excitation of nuclear transitions
• Recollision induced nuclear excitation of ${}^{229}$Th
• A scheme for excitation of thorium-229 nuclei based on the electronic bridge excitaion
• Driven electronic bridge processes via defect states in ${}^{229}$Th-doped crystals
• Optical Transmission Enhancement of Ionic Crystals via Superionic Fluoride Transfer: Growing VUV-Transparent Radioactive Crystals
• Nuclear coherent population transfer to the ${}^{229m}$Th isomer using x-ray pulses
• Excitation and probing of low-energy nuclear states at high-energy storage rings
• Precision measurements with cold atoms and trapped ions
• Estimation of radiative half-life of ${}^{229m}$Th by half-life measurement of other nuclear excited states in ${}^{229}$Th
• Absolute X-ray energy measurement using a high-accuracy angle encoder
• Development of a recoil ion source providing slow Th ions including ${}^{229(m)}$Th in a broad charge state distribution
• Internal conversion of the low energy ${}^{229m}$Th isomer in the Thorium anion
• Studies of thorium and ytterbium ion trap loading from laser ablation for gravity monitoring with nuclear clocks
• A continuous-wave vacuum ultraviolet laser for the nuclear clock
• Proposal for a Nuclear Light Source
• Production and chemical separation of ${}^{229}$Pa toward observation of $\gamma$ rays of ${}^{229\mathrm{m}}$Th
• Constraints on the Variation of the QCD Interaction Scale ${\Lambda }_{\text{QCD}}$
• 'Phase Transition' in the 'Thorium-Isomer Story'
• Sensitivity of Neutron-Rich Nuclear Isomer Behavior to Uncertainties in Direct Transitions