Nuclear moments and isotope shifts of the actinide isotopes 249-253Cf probed by laser spectroscopy

We report on high-resolution laser spectroscopy studies on 249-253Cf 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 249Cf with improved precision to mu I(249Cf) = -0.395(17 )mu N, whereas mu I(251Cf) = -0.571(24 )mu N and mu I(253Cf) = -0.731(35 )mu N were derived for the first time. Additionally, the spectroscopic quadrupole moments QS(249Cf) = 6.27(33) eb and QS(253Cf) = 5.53(51) eb were extracted.