58Ni(p, p′γ) 58Ni angular correlation measurements

Abstract

Angular correlation measurements in a 180° geometry for the 58Ni(p, p′γ) reaction were used to determine the spins and γ-ray decay properties of states at 2.46, 2.78, 3.04 and 3.26 MeV. The 2.46 MeV state was verified to be spin J = 4, and the states at 2.78, 3.04 and 3.26 MeV were assigned spin J = 2. The (L+1)/L mixing ratio for the 2.78 → 1.46 MeV transition is δ = 1.5 −0.4 +1.5, strongly suggesting positive parity for this state. Using the available information for the ground state branching of this 2 2 + state, the crossover to cascade ratio of the E2 transition rates is in disagreement by a factor of ≈ 10 4 with the recent shell-model predictions of Cohen et al. For the 3.04 and the 3.26 MeV levels the mixing ratios δ for transitions to the 2 1 + state are −0.1±0.15 and −0.4±0.2 with the corresponding branchings to the ground state of 38±2% and 64±2%, respectively.