Nuclear spins, moments, and changes of the mean square charge radii of140−153Eu

The hyperfine structures and isotope shifts of 14 isotopes of Eu (Z=63) in the mass range 140≦A≦153, partly with isomeric states, have been measured in the atomic transitions at 4,594 A and 4,627 A, using the technique of collinear fast-beam laser spectroscopy at the ISOLDE facility at CERN. The nuclear spins, the magnetic dipole and electric quadrupole moments, and the changes in the mean square charge radii have been evaluated. These nuclear parameters clearly reflect the effects of theN=82 neutron-shell closure in the single-proton hole states with respect to the semi-magic gadolinium (Z=64), and theN=88−90 shape transition.