Intermediate structure resonances in the inelastic scattering ofC12onO16

Excitation functions for inelastic scattering of ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ + ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ to the $2^{+}$ state in ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ at 4.43 MeV, the ($3^{-}$, $0^{+}$) doublet at 6.1 MeV and the ($2^{+}$, $1^{-}$) states at 7.0 MeV in ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ have been measured over the energy range $33\le E_{\mathrm{lab}}\le 54$ MeV in 200-keV steps, at c.m. angles ranging from 100° to 165°. Several new intermediate structure resonances are observed in the inelastic channels. A statistical analysis reveals strong correlations in angle and in exit channels. Complete elastic and inelastic angular distributions were measured at the energies of $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=13.6, 19.7, 20.5, 22.0, \mathrm{and} 22.6$ MeV as well as as at 21.3 MeV. Optical model fits to the elastic angular distributions result in the spin assignments $J=9^{-}, {14}^{+}, \mathrm{and} {15}^{-}\left({16}^{+}\right)$ ${14}^{+}$, and ${15}^{-}$ (${16}^{+}$) for the resonances at $E_{\mathrm{c}.\mathrm{m}.\mathrm{}}=13.6, 19.7, \mathrm{and} 22.0$ 19.7, and 22.0 MeV, respectively. Partial widths are extracted from the data. The reduced widths of the inelastic channels are large, establishing their importance in the resonance mechanism. The results are compared to predictions of existing models, and it is found that a simple double-resonance model does not adequately describe the data.