English

Fine-structure constant sensitivity of the Th-229 nuclear clock transition

Nuclear Theory 2024-07-25 v1 Nuclear Experiment Atomic Physics

Abstract

State-resolved laser spectroscopy at the 1012^{-12} precision level recently reported in arXivarXiv:2406.18719 determined the fractional change in nuclear quadrupole moment between the ground and isomeric state of 229Th^{229}\rm{Th}, ΔQ0/Q0\Delta Q_0/Q_0=1.791(2) %. Assuming a prolate spheroid nucleus, this allows to quantify the sensitivity of the nuclear transition frequency to variations of the fine-structure constant α\alpha to K=5900(2300)K=5900(2300), with the uncertainty dominated by the experimentally measured charge radius difference Δr2\Delta \langle r^2 \rangle between the ground and isomeric state. This result indicates a three orders of magnitude enhancement over atomic clock schemes based on electron shell transitions. We find that ΔQ0\Delta Q_0 is highly sensitive to tiny changes in the nuclear volume, thus the constant volume approximation cannot be used to accurately relate changes in r2\langle r^2 \rangle and Q0Q_0. The difference between the experimental and estimated values in ΔQ0/Q0\Delta Q_0/Q_0 raises a further question on the octupole contribution to the alpha-sensitivity.

Keywords

Cite

@article{arxiv.2407.17300,
  title  = {Fine-structure constant sensitivity of the Th-229 nuclear clock transition},
  author = {Kjeld Beeks and Georgy A. Kazakov and Fabian Schaden and Ira Morawetz and Luca Toscani de Col and Thomas Riebner and Michael Bartokos and Tomas Sikorsky and Thorsten Schumm and Chuankun Zhang and Tian Ooi and Jacob S. Higgins and Jack F. Doyle and Jun Ye and Marianna S. Safronova},
  journal= {arXiv preprint arXiv:2407.17300},
  year   = {2024}
}

Comments

10 pages, 2 figures