We report on high-resolution laser spectroscopy studies on ${}^{249\text{–}253}\mathrm{Cf}$ with spectral linewidths in the order of 100 MHz carried out at the RISIKO mass separator at Mainz University. In total three atomic ground-state transitions were investigated and the hyperfine parameters for the odd-$A$ isotopes and isotope shift for all examined isotopes have been determined from the measured spectra. The isotope shift measurements allowed tracking of changes in mean-squared charge radii across the deformed nuclear shell closure at $N=152$, whereby shape discontinuities were not observed. Experimental hyperfine coupling constants of the atomic ground state were combined with relativistic many-body atomic calculations to extract the nuclear magnetic-dipole moment of ${}^{249}\mathrm{Cf}$ with improved precision to ${\mu }_I{(}^{249}\mathrm{Cf})=-0.395\left(17\right){\mu }_N$, whereas ${\mu }_I{(}^{251}\mathrm{Cf})=-0.571\left(24\right){\mu }_N$ and ${\mu }_I{(}^{253}\mathrm{Cf})=-0.731\left(35\right){\mu }_N$ were derived for the first time. Additionally, the spectroscopic quadrupole moments $Q_{\mathrm{S}}{(}^{249}\mathrm{Cf})=6.27\left(33\right)e\mathrm{b}$ and $Q_{\mathrm{S}}{(}^{253}\mathrm{Cf})=5.53\left(51\right)e\mathrm{b}$ were extracted.

• Received 20 December 2022
• Accepted 7 February 2023

DOI:https://doi.org/10.1103/PhysRevC.107.034313

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Published by the American Physical Society