229Thorium-doped calcium fluoride for nuclear laser spectroscopy. Computer modelling of thorium doping in LiCaAlF 6 and LiSrAlF 6: application to the development of solid state optical frequency devices. Attempt to optically excite the nuclear isomer in 229Th. Results of a direct search using synchrotron radiation for the low-energy 229Th nuclear isomeric transition. Multiply charged thorium crystals for nuclear laser spectroscopy. Laser ablation loading of a radiofrequency ion trap. Charge and energy distributions of recoils from Th 226 alpha decay. Development of a recoil ion source providing slow Th ions including 229(m)Th in a broad charge state distribution. Determination of the extraction efficiency for 233U source α-recoil ions from the MLL buffer-gas stopping cell. Atomic susceptibilities and shielding factors. Two-photon laser excitation of trapped 232Th + ions via the 402-nm resonance line. Trapping and sympathetic cooling of single thorium ions for spectroscopy. Electronic level structure of Th + in the range of the 229mTh isomer energy. Wigner crystals of 229Th for optical excitation of the nuclear isomer. Nuclear radii of thorium isotopes from laser spectroscopy of stored ions. 27Al + quantum-logic clock with a systematic uncertainty below 10 −18. Optical clock comparison for Lorentz symmetry testing. Electromagnetic traps for charged and neutral particles. Towards high-resolution laser ionization spectroscopy of the heaviest elements in supersonic gas jet expansion. Alternative approach to populate and study the 229Th nuclear clock isomer. Precise γ-spectroscopy measurement of the isomer energy. Energy splitting of the ground-state doublet in the nucleus 229Th. On the energy of the 3.5-eV level in 229Th. Lifetime measurement of the 229Th nuclear isomer. Reduced transition probabilities for the gamma decay of the 7.8 eV isomer in 229Th. Magnetic dipole and electric quadrupole moments of the 229Th nucleus. Laser spectroscopic investigation of properties of the 229 Th isomer. Laser spectroscopic characterization of the nuclear-clock isomer 229mTh. Nuclear structure of lowest 229Th states and time-dependent fundamental constants. Litvinova, E., Feldmeier, H., Dobaczewski, J. Hyperfine structure of the atomic spectrum and the nuclear moments of the thorium-229 isotope. Uses for uranium-233: what should be kept for future needs? ORNL 6952, 7 (1999). The 229Th isomer: prospects for a nuclear optical clock. 7th Symposium on Frequency Standards and Metrology, ISFSM 2008, 532–538 (World Scientific, 2009). Prospects for a nuclear optical frequency standard based on thorium-229. Properties of the optical transition in the 229Th nucleus. Lasers as a bridge between atomic and nuclear physics. The 229-thorium isomer: doorway to the road from the atomic clock to the nuclear clock. Nuclear clocks based on resonant excitation of γ-transitions. Features of the low-energy level scheme of 229Th as observed in the α-decay of 233U. A detailed theoretical analyis of the achievable accuracy of a 229 Th nuclear clock with trapped ions. Single-ion nuclear clock for metrology at the 19th decimal place. Proposal of a high-precision optical nuclear clock based on 229 Th.Ĭampbell, C. Nuclear laser spectroscopy of the 3.5 eV transition in Th-229. A new method of measuring nuclear magnetic moment. Über die hyperfeinstruktur des Europiums. Zur Frage der theoretischen Deutung der Satelliten einiger Spektrallinien und ihrer Beeinflussung durch magnetische Felder. Because the nuclear transition energy is in the range of transitions of valence electrons, the electronic state may influence the nuclear excitation and decay rates.īecause of a fine balance of contributions from the strong and electromagnetic interactions to the nuclear transition energy, a 229Th clock would be sensitive to predicted effects of physics beyond the standard model, such as temporal or spatial variations of fundamental constants. Thorium-229 is studied as trapped atomic ions in vacuum or doped into transparent crystals such as CaF 2. Recent experiments have provided essential information on the nuclear properties of 229Th (half-life 7,920 years), such as the nuclear moments, decay modes of the isomer and a more precise value of the isomer excitation energy, which is required to achieve laser excitation. The 229Th nucleus is the prime candidate for the realization of a nuclear clock because it possesses a low-energy (8 eV) excited state that is amenable to resonant laser excitation from the nuclear ground state, with an expected natural linewidth in the millihertz range. A nuclear clock, based on a radiative transition in the nucleus, is less sensitive to external perturbations and therefore potentially more precise than established atomic clocks that are based on transitions in the electron shell.
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