Nuclear charge radii of ${}^{229}$Th from isotope and isomer shifts

Abstract

The isotope ${}^{229}$Th is unique in that it possesses an isomeric state of only a few eV above the ground state, suitable for nuclear laser excitation. An optical clock based on this transition is expected to be a very sensitive probe for variations of fundamental constants, but the nuclear properties of both states have to be determined precisely to derive the actual sensitivity. We carry out isotope shift calculations in Th${}^{+}$ and Th${}^{2+}$ including the specific mass shift, using a combination of configuration interaction and all-order linearized coupled-cluster methods and estimate the uncertainty of this approach. We perform experimental measurements of the hyperfine structure of Th${}^{2+}$ and isotopic shift between ${}^{229}$Th${}^{2+}$ and ${}^{232}$Th${}^{2+}$ to extract the difference in root-mean-square radii as $\delta ⟨r^2{⟩}^{232,229}=0.299(15)$ fm${}^2$. Using the recently measured values of the isomer shift of lines of ${}^{229\text{m}}$Th, we derive the value for the mean-square radius change between ${}^{229}$Th and its low lying isomer ${}^{229\text{m}}$Th to be $\delta ⟨r^2{⟩}^{229\text{m},229}=0.0105(13){\mathrm{fm}}^2$.

arXiv comment5 pages, 2 figures

References in corpus (22)

• Nuclear Ground-State Masses and Deformations
• Hunting for topological dark matter with atomic clocks
• Searching for dilaton dark matter with atomic clocks
• Improved limit on a temporal variation of $m_p/m_e$ from comparisons of Yb${}^{+}$ and Cs atomic clocks
• Direct detection of the 229Th nuclear clock transition
• Enhanced effect of temporal variation of the fine structure constant in diatomic molecules
• Development of a configuration-interaction + all-order method for atomic calculations
• Laser spectroscopic characterization of the nuclear clock isomer ${}^{229m}$Th
• 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
• Reduced transition probabilities for the gamma decay of the 7.8 eV isomer in ${}^{229}$Th
• On Th229 and time-dependent fundamental constants
• Calculation of isotope shifts for cesium and francium
• Relativistic corrections to isotope shift in light ions
• Two-photon laser excitation of trapped 232Th+ ions via the 402 nm resonance line
• The electric quadrupole channel of the 7.8 eV ${}^{229}\mathrm{Th}$ transition
• Broadening and intensity redistribution in the Na($3p$) hyperfine excitation spectra due to optical pumping in the weak excitation limit
• Hyperfine structure in ${}^{229g}$Th${}^{3+}$ as a probe of the ${}^{229g}$Th $\to$ ${}^{229m}$Th nuclear excitation energy
• Splitting Sensitivity of the Ground and 7.6 eV Isomeric States of 229Th
• Observation of an unexpected negative isotope shift in 229Th+ and its theoretical explanation
• Hyperfine interaction with the ${}^{229}$Th nucleus and its low lying isomeric state
• Isotope Shifts in the 7s$\to$8s Transition of Francium: Measurements and Comparison to \textit{ab initio} Theory

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• pCI: a parallel configuration interaction software package for high-precision atomic structure calculations
• On the sensitivity of nuclear clocks to new physics
• Internal conversion of the low energy ${}^{229m}$Th isomer in the Thorium anion
• Laser Spectroscopy of the y${}^7$P${}_J^{\circ }$ states of Cr I
• Prediction of Nuclear Clock Transitions Frequency Difference between ${}^{229}$Th${}^{3+}$ and ${}^{229}$Th${}^{4+}$ via \textit{ab-initio} Self-Consistent Field Theory
• Oscillating nuclear charge radii as sensors for ultralight dark matter
• Shift of nuclear clock transition frequency in ${}^{229}$Th ions due to hyperfine interaction
• Comprehensive Assessment of ${\mathrm{Th}}^{3+}$ Properties for Nuclear Clock and Fundamental Physics Applications