Gamma-Ray Decay of the 6.92-, 7.12-, 8.88-, and 13.10-MeV States inO16

Abstract

The reactions ${\mathrm{F}}^{19}(p,\alpha ){\mathrm{O}}^{16}$ and ${\mathrm{N}}^{15}(p,\gamma ){\mathrm{O}}^{16}$ have been used to study the $\gamma$-ray branching of ${\mathrm{O}}^{16}$ states at 6.92, 7.12, 8.88, and 13.10 MeV. Measurements were made with two 5×6-in. and two 3×3-in. NaI (Tl) detectors in various coincidence combinations. Two-dimensional pulse-height analysis was employed in some cases. The $\gamma$-ray branches from the $J^{\pi }=2^{+}6.92-\mathrm{a}\mathrm{n}\mathrm{d} 1^{-}7.12-$MeV states to the $J^{\pi }=3^{-}6.13$-MeV level were found to be ≤ 8 × ${10}^{-5\mathrm{}}$ and (7.0±1.4) × ${10}^{-4\mathrm{}}$, respectively. For the $J^{\pi }=2^{-}8.88$-MeV level the branches to the 7.12-, 6.92-, 6.13-MeV, and ground states are (12.6±2.0)%, (4.2±0.8)%, (76.0±3.0)%, and (7.2±0.8)%, respectively. The $E1\mathrm{}$ branch, 13.10 → 6.06 MeV, was observed to have an intensity of (5.8±1.2) × ${10}^{-3\mathrm{}}$, corresponding to a $B\left(E1\mathrm{}\right)\mathrm{}$ of 0.037 relative to that of the $E1\mathrm{}$ ground-state transition. The significance of the various results in the description of states in ${\mathrm{O}}^{16}$ is discussed.