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Magnetic dipole and electric quadrupole moments of the 229Th nucleus

We calculate the A and B hyperfine constants for the low-lying states of 229Th3+ using a high-precision relativistic all-order approach. By combining these calculations with measurements of the 6d and 5f hyperfine constants [C. J. Campbell et al., Phys. Rev. Lett. 106, 223001 (2011)], we determine the magnetic dipole μ=0.360(7)μ_B and the electric-quadrupole Q=3.11(6) eb moments of the 229Th nucleus. Our value for μis five times more accurate and is 22% smaller than the best previous value μ=0.46(4) μ_B [S. Gerstenkorn et al., J. Phys. (Paris) 35, 483 (1974)], while our value for Q is the same, but 2.5 times more accurate than the 2011 result. A systematic study of hyperfine structure in eight other monovalent atoms supports our claim of 2% level uncertainty for $μ$ and Q in 229Th+3.