GROUND-STATE HYPERFINE-STRUCTURE MEASUREMENTS OF UNSTABLE EU-ION TRAP( ISOTOPES IN A PAUL)

Hyperfine separations in unstable Eu+ ions of mass 148, 149, and 150 h ave been measured in laser-microwave double-resonance experiments in a Paul ion trap. In spite of the small available quantities of the isot opes, the experimental uncertainties are of the order of 10(-8) or bel ow, which is of the same order as in earlier measurements on stable is otopes of Eu+. Extensive second-order perturbation calculation is requ ired to obtain coupling constants for magnetic-dipole (A) and electric -quadrupole (B) interactions. The uncertainties are a few times 10(-7) for A and 10(-3) for B. The experiments are a step in an attempt to d etermine the differential hyperfine anomaly (Bohr-Weisskopf effect) in a long chain of isotopes.