The reactions ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}({}_{}{}^3{}_{}{}^{}\mathrm{He}, n){}_{}{}^{13}{}_{}{}^{}\mathrm{N}_{}^{*}{}_{}{}^{}$ ($T=\frac{3}{2}$) ($\gamma$) and ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}({}_{}{}^3{}_{}{}^{}\mathrm{He}, p){}_{}{}^{13}{}_{}{}^{}\mathrm{C}_{}^{*}{}_{}{}^{}$ ($T=\frac{3}{2}$) ($\gamma$) have been used to study the $\gamma$-decay modes of the lowest $T=\frac{3}{2}$ states in ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$ and ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$. Coincidences between neutrons and associated $\gamma$ rays in the case of ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$ and between protons and $\gamma$ rays in the case of ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$ were recorded in a two-dimensional array. For the $\gamma$ decay of ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$(15.07) and ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$(15.11), we find $\frac{{\Gamma }_{{\gamma }_0}}{{\Gamma }_{p_0}}=(12\mathrm{}\pm 2)\%$ and $\frac{{\Gamma }_{{\gamma }_0}}{\Gamma }=(0.53\mathrm{}\pm 0.06)\%$, respectively. When combined with previously available experimental information, these values yield $\Gamma =1.13\mathrm{}\pm 0.3 \mathrm{and} 4.7\pm 1.6$ keV for the first $T=\frac{3}{2}$ levels in ${}_{}{}^{13}{}_{}{}^{}\mathrm{N}$ and ${}_{}{}^{13}{}_{}{}^{}\mathrm{C}$, respectively. Additional information on $\gamma$ branching ratios and particle decay for these levels is presented.

• Received 20 August 1968

DOI:https://doi.org/10.1103/PhysRev.176.1120