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

Nuclear laser spectroscopy at the 10⁻¹² precision level (Nature 633.8028 (2024): 63–70) determined the fractional change in the nuclear quadrupole
moment of ²²⁹Th upon excitation, ΔQ₀/Q₀ = 1.791(2)%. Such high-accuracy nuclear parameters enable stringent tests and refinement of ²²⁹Th nuclear
models. Using a semi-classical prolate-spheroid model, we quantify the transition frequency’s sensitivity to fine-structure constant variations as