A band-crossing model that has been proposed as a possible mechanism for resonances in heavy ion reactions is applied to energy dependent structure in the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ system. The recently observed intermediate-width structure in the 6.13 MeV gamma-radiation yield can be well understood in terms of the band-crossing model, assuming the crossing of the elastic potential resonance band and an aligned rotational band in which the intrinsic spin ($3\hslash$) and the relative angular momenta are coupled to their maximum value. Numerical calculations based on this model reproduce all of the observed energy dependent structure of the cross section in the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ interaction, i.e., the gamma-radiation yield from the $3_1^{-}$ state of ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$, as well as the total fusion and elastic scattering data. Each oscillation in the fusion excitation function is interpreted as reflecting a shape resonance of each new grazing partial wave in the entrance channel as it becomes active with increasing energy. The observed anticorrelation of the total fusion and the 90° excitation function of elastic scattering data is reproduced naturally by the model. It is concluded that these data support the existence of nuclear molecular resonances in the ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ system.

NUCLEAR REACTIONS ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ + ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ scattering, $10<~E_{\mathrm{c}.\mathrm{m}.\mathrm{}}<~41$ MeV; calculated elastic scattering excitation functions, fusion cross sections, and $3_1^{-}$ inelastic cross sections. Resonance mechanism for heavy ion reactions.

• Received 28 February 1980

DOI:https://doi.org/10.1103/PhysRevC.22.1068