Rotation, pairing and blocking in high-K isomers explored through the rotational g-factor

Abstract

The paired superfluid system of nucleons in nuclei, and their excitations, present properties of general physics interest. Collective magnetic g-factors gR, obtained from a novel analysis of data for multi-quasi-particle configurations in high- Kisomers, are shown to exhibit a striking systematic variation with the relative number of proton and neutron quasi-particles, Np − Nn. Basic ideas of pairing, its quenching by quasi-particle excitation and the consequent changes to moment of inertia and collective magnetism are discussed. Existing model calculations do not reproduce the observed gR variation adequately. The new findings open a fresh window on these effects and raise the important question of just which nucleons contribute to the ‘collective’ properties of these nuclei.