Nuclear moment studies with polarized radioactive nuclear beams

Beams of spin-polarized radioactive nuclei are produced in the projectile fragmentation reaction induced by intermediate-energy heavy ion beams, and are used for the measurement of magnetic dipole and electric quadrupole moments of nuclei in the regions far from stability. In this paper, after remarking the mechanism of fragment polarization and the experimental techniques to make use of it, we discuss the recent results obtained for the electromagnetic moments of light neutron-rich nuclei at RIKEN. Analyses of the observed magnetic moments in terms of shell models show intriguing results which imply that some of the basic nuclear properties, such as the order in energy of the single-particle orbits, the pairing energy between the excess neutrons, and the effective gs-factor for a halo nucleon, tend to alter as the degree of neutron excess increases. Also, the measured electric quadrupole moments reveal remarkable quenching of the E2 effective charge in nuclei with large N/Z ratios