Magnetic moments, lifetimes and γ-decay of the lowest 6 − states in 64Cu and 66Cu

Abstract

The doubly-odd nuclei 64Cu and 66Cu are investigated by means of γ-ray spectroscopy following 63,65Cu(d, p) with pulsed 6.5 MeV deuterons. The energies of about 80 transitions between 50 and 1450 keV are redetermined. Two isomeric levels are discovered in 64 Cu (1594 keV, τ = 29.5±1.0 nsec) and in 66 Cu (1154 keV, τ = 860±30 nsec) . By time-differential perturbed angular distribution measurements on all delayedy-rays a strong similarity between parts of the level schemes of 64Cu and 66Cu becomes apparent. Both isomers have J π = 6 − and decay through a cascade 6 −(M2) 4 +(Ml) 3 + (Ml) 2 +(Ml) 1 + with only a weak E2 admixture, and without branching to levels outside this quartet. Both M2 transitions are hindered by a factor of about 30 which is usual in this mass region. The magnetic moments of both 6 − states are measured to be +1.06±0.03 n.m. and +1.038±0.003 n.m. for 64Cu and 66Cu respectively. They are well explained by the additive coupling of a case3 2 − proton moment and a case9 2 + neutron moment taken from neighbouring odd-even and even-odd nuclei.