Precision Calculation of Hyperfine Constants for Extracting Nuclear Moments of 229Th

Determination of nuclear moments for many nuclei relies on the computation of hyperfine constants, with theoretical uncertainties directly affecting the resulting uncertainties of the nuclear moments. In this work, we improve the precision of such a method by including for the first time an iterative solution of equations for the core triple cluster amplitudes into the relativistic coupled-cluster method, with large-scale complete basis sets. We carried out calculations of the energies and magnetic dipole and electric quadrupole hyperfine structure constants for the low-lying states of Th-229(3+) in the framework of such a relativistic coupled-cluster single double triple method. We present a detailed study of various corrections to all calculated properties. Using the theory results and experimental data, we found the nuclear magnetic dipole and electric quadrupole moments to be mu = 0.366(6)mu(N) and Q = 3.11(2) eb, respectively, and reduce the uncertainty of the quadrupole moment by a factor of 3. The Bohr-Weisskopf effect of the (mite nuclear magnetization is investigated, with bounds placed on the deviation of the magnetization distribution from the uniform one.

Automated summary

This study improves the precision of determining nuclear moments by iteratively solving equations for core triple cluster amplitudes in the relativistic coupled-cluster method. Calculations for Th-229(3+) low-lying states were conducted, resulting in nuclear magnetic dipole and electric quadrupole moments with reduced uncertainties. The investigation also touched upon the Bohr-Weisskopf effect and placed constraints on deviations in nuclear magnetization distribution.