Polarized Radioactive Beams and Nuclear Moment Measurements for Exotic Nuclei

Viewing a nucleus as a collection of independent particles has been, since the spin-orbit force was introduced [1], a successful way of understanding major nuclear properties that are governed by a particular series of numbers—the magic numbers. Such properties result from the bunching of the single-particle orbits, or the existence of nuclear shells. About half a century after, however, the present-day studies of nuclei far from the β stability line reveal that the nuclear shells may evolve [2]: As the N/Z ratio increases, the single particle orbits migrate upward or downward in energy depending on their j = l ± 1/2 character. As a result the decisive role played by one orbit (the valence orbit) is taken over by another, and in some cases the nuclear deformation sets in even in a nucleus whose N or Z number is a (heretofore) magic number. In such a situation, the nuclear moments, namely the magnetic dipole moments μ and electric quadrupole moments Q, serve as very useful indicators for alterations in nuc...