Photon spectra of the reaction ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}$($p$,$\gamma$) ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ at $E_p=40, 60, \mathrm{and} 80$ MeV are calculated assuming a direct-capture mechanism. Observed capture spectra below 25-MeV excitation energy are reproduced well. Only about half of the observed cross section at the 19.2-MeV peak is found to come from the $4^{-}$ stretched configurations. Contributions of "charge-exchange currents" are shown to be important.

• Received 14 June 1979

DOI:https://doi.org/10.1103/PhysRevLett.43.576