The γ-decay of the [formula omitted] analogue state in 59Cu

Abstract

An investigation of the γ-decay of the 1 g 9 2 analogue state in 59Cu has been performed using the 58Ni(p, γ) 59Cu reaction. The (p, γ) excitation function has been taken in the range E p = 3450–3650 keV. The decay schemes of the (p, γ) resonances at E p = 3483, 3532 and 3547 keV, measured with Ge(Li) detectors, lead to eight new levels in 59Cu with excitation energies between 1.8 and 4.7 MeV and to spin assignments of several states. The spins of the first two resonances are found to be ( 1 2 , 3 2 ) and ( 5 2 ). The spin of the E p = 3547 keV resonan is, from angular distributions, uniquely determined to be J π = 9 2 + and this state is found to be the unfragmented analogue state of the E ∗ = 3.062 MeV , J π = 9 2 + parent state in 59Ni. The measured complete decay scheme of this resonance shows that its isovector M1 decay is in disagreement with all existing theoretical predictions.