Resonances at $E_{\alpha }=401,814, \mathrm{and} 953$ keV were observed in the ${}_{}{}^7{}_{}{}^{}\mathrm{Li}(\alpha ,\gamma )$ reaction. From the thick target yields the corresponding states in ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$ at 8920, 9185, and 9274 keV were found to have center-of-mass resonance strengths of 0.0088±0.0014, 0.317±0.047, and 1.72±0.17 eV, respectively. The radiative widths deduced for the latter two states are ${0.17}_{-0.03\mathrm{}}^{+0.06\mathrm{}}$ and 1.15±0.16 eV, respectively. Using a 40 mCi ${}_{}{}^7{}_{}{}^{}\mathrm{Be}$ target, $\alpha$-capture resonances were observed at $E_{\alpha }=884\mathrm{}$ (${}_{}{}^{11}{}_{}{}^{}\mathrm{C}_{}^{*}{}_{}{}^{}$ = 8105 keV) and 1376 (${}_{}{}^{11}{}_{}{}^{}\mathrm{C}_{}^{*}{}_{}{}^{}$ = 8421 keV) keV with center-of-mass resonance strengths of 0.331±0.041 and 3.80±0.57 eV, respectively. The radiative widths deduced for these states are 0.350±0.056 and 3.1±1.3 eV, respectively. The observed decay rates are compared with theoretical calculations.

• Received 2 December 1983

DOI:https://doi.org/10.1103/PhysRevC.29.1199