Delayed alignments in the N=Z nuclei 84Mo and 88Ru

Abstract

The yrast band of the N=Z nucleus 84Mo has been extended up to the 101 state. Its moment of inertia varies smoothly up to this state (rotational frequency 0.6 MeV). The new data confirm the systematic delay of the particle alignment frequency in N=Z nuclei with respect to the neighboring N>Z nuclei, which has been suggested as a signature of the neutron-proton pairing interaction. Projected shell model calculations performed for the heaviest N=Z nuclei studied so far, 84Mo and 88Ru, predict that the confirmation of a possible enhancement of the neutron-proton residual interaction requires the observation of still higher spins in these nuclei.