Gamma Decay of the LowestT=32State ofN13

Abstract

$\gamma$-ray transitions are observed in the reaction ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}(p, \gamma ){}_{}{}^{13}{}_{}{}^{}\mathrm{N}$ from the sharp $T=\frac{3}{2}$ resonance at $E_x=15.07\mathrm{}$ MeV in ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$ to the ground state and to higher excited states. For the ground-state transition, $\frac{{\Gamma }_p{\Gamma }_{\gamma }}{\Gamma }=5.5\mathrm{}\pm 0.8$ eV. The angular distribution of this transition confirms $J^{\pi }={\frac{3}{2}}^{-}$ for the $T=\frac{3}{2}$ state and gives an amplitude ratio of $\frac{E2\mathrm{}}{M1\mathrm{}}=-0.095\mathrm{}\pm 0.07$, in agreement with theory in sign and magnitude. The widths for decay to the ground and excited states are compared with shell-model predictions, and with the analog $\beta$ transitions in the decay of ${}_{}{}^{13}{}_{}{}^{}\mathrm{B}$.