Direct detection of the 229Th nuclear clock transition

Abstract

Today's most precise time and frequency measurements are performed with optical atomic clocks. However, it has been proposed that they could potentially be outperformed by a nuclear clock, which employs a nuclear transition instead of the atomic shell transitions used so far. By today there is only one nuclear state known which could serve for a nuclear clock using currently available technology, which is the isomeric first excited state in ${}^{229}$Th. Here we report the direct detection of this nuclear state, which is a further confirmation of the isomer's existence and lays the foundation for precise studies of the isomer's decay parameters. Based on this direct detection the isomeric energy is constrained to lie between 6.3 and 18.3 eV, and the half-life is found to be longer than 60 s for ${}^{229\mathrm{m}}$Th${}^{2+}$. More precise determinations appear in reach and will pave the way for the development of a nuclear frequency standard.

References in corpus (9)

• Systematic evaluation of an atomic clock at 2e-18 total uncertainty
• Enhanced effect of temporal variation of the fine structure constant in diatomic molecules
• Proposal for a Nuclear Gamma-Ray Laser of Optical Range
• Performance of a 229 Thorium solid-state nuclear clock
• Nuclear clocks based on resonant excitation of gamma-transitions
• On Th229 and time-dependent fundamental constants
• Determination of the extraction efficiency for ${}^{233}$U source $\alpha$-recoil ions from the MLL buffer-gas stopping cell
• Splitting Sensitivity of the Ground and 7.6 eV Isomeric States of 229Th
• Results of a direct search using synchrotron radiation for the low-energy ${}^{229}$Th nuclear isomeric transition

Cited by in corpus (8)

• Lifetime measurement of the ${}^{229}$Th nuclear isomer
• A laser excitation scheme for ${}^{229\text{m}}$Th
• Excitation of the ${}^{229}$Th nucleus via a two-photon electronic transition
• Internal conversion from excited electronic states of ${}^{229}\mathrm{T}h$ ions
• Magnetic hyperfine structure of the ground-state doublet in highly charged ions ${}^{229}$Th${}^{89+,87+}$ and the Bohr-Weisskopf effect
• The concept of laser-based conversion electron Mössbauer spectroscopy for a precise energy determination of ${}^{229m}$Th
• Catching, trapping and in-situ-identification of thorium ions inside Coulomb crystals of ${}^{40}$Ca${}^{+}$ ions
• Nuclear excitation by two-photon electron transition