The giant $E1\mathrm{}$ resonances of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ have been studied with the polarized-proton capture reactions ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}(p,{\gamma }_0){}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ and ${}_{}{}^{11}{}_{}{}^{}\mathrm{B}(p,{\gamma }_1){}_{}{}^{12}{}_{}{}^{}\mathrm{C}$. The effects of proton polarization on the angular distributions were large and of opposite sign for ${\gamma }_0$ and ${\gamma }_1$. Coupled with the unpolarized measurements the polarized results produce additional significant limitations on the allowed configurations of the giant $E1\mathrm{}$ resonances in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$.

• Received 22 February 1972

DOI:https://doi.org/10.1103/PhysRevLett.28.766