The ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$+ ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ elastic scattering has been measured for $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=14.6-31.3\mathrm{}$ MeV, ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}=30\mathrm{}°-110\mathrm{}°$. The elastic data have been analyzed via a phase shift analysis, enabling the extraction of model independent sets of phase shift parameters. The extracted $J^{\pi }$ values for the intermediate structure resonances at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=18.4, 19.3, \mathrm{and} 20.3$ MeV are ${12}^{+}$, ${12}^{+}$, and ${12}^{+}$ or ${14}^{+}$, respectively. The questions of ambiguities in the phase shift analysis and the comparison with $J^{\pi }$ values deduced from other experiments are discussed. Evidence is presented for the existence of gross structure resonances. The elastic scattering has also been analyzed using the sum-of-differences method to directly extract the total reaction cross section. The results of these analyses are compared to existing models of the origin of intermediate structure resonances.

NUCLEAR REACTIONS Measured the ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$+ ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ elastic scattering, $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=14.6-31.3\mathrm{}$ MeV, ${\theta }_{\mathrm{c}.\mathrm{m}.\mathrm{}}=30\mathrm{}°-110\mathrm{}°$. Phase shift analysis, sum-of-differences analysis.

• Received 7 September 1982

DOI:https://doi.org/10.1103/PhysRevC.27.1103