The cross section for the ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$($p$,$\gamma$)${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ reaction leading to the 19 MeV region of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ has been measured at ${\theta }_{\mathrm{lab}}=60\mathrm{}°$ for $E_p$ of 23 to 60 MeV. Angular distributions of cross sections and analyzing powers were measured at $E_p=28.7\mathrm{}$ MeV. The ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$($p$,${\gamma }_{0,1}$)${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ cross sections were measured at ${\theta }_{\mathrm{lab}}=60\mathrm{}°$ for $E_p$ of 8 to 60 MeV, with angular distribution measurements at $E_p$ of 14.5, 17.0, and 28.7 MeV. The results are compared to direct capture calculations which, in the case of transitions to the 19 MeV region, treat the final state as both a bound and unbound state. The procedures for calculating direct capture to unbound final states are described. The possible existence of a giant resonance state is discussed.

NUCLEAR REACTIONS ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$($p$,$\gamma$)${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$; measured $\sigma \mathrm{}\left(E\right)\mathrm{}$ for transitions to the 19 MeV region of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ at $\theta =60\mathrm{}°$ for $E_p$ of 23 to 60 MeV, measured $\sigma \left(\theta \right)$ and $A\left(\theta \right)$ at 28.7 MeV for these transitions. ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$($p$,${\gamma }_{0,1}$)${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$, measured $\sigma \left(60\mathrm{}°\right)$ for $E_p$ of 8 to 60 MeV, $\sigma \left(\theta \right)$ at 14.5, 17.0, and 28.7 MeV. Results are compared to direct capture calculations treating the final state both as bound and unbound. Procedures for calculating direct capture to unbound final states are described. The possible existence of giant resonance states is discussed.

• Received 7 January 1982

DOI:https://doi.org/10.1103/PhysRevC.25.2921