The nuclear structure of ${}^{24}\mathrm{Mg}$ with ${}^{12}\mathrm{C}+3\mathrm{}\alpha$ and $3\alpha +3\mathrm{}\alpha$ configurations, existing at an extremely highly-excited energy domain is studied by the microscopic coupled-channels (MCC) calculation based on the double-folding interactions using 3α-RGM wave functions of ${}^{12}\mathrm{C}$ and a realistic nucleon-nucleon interaction called DDM3Y. The dinuclear ${}^{12}\mathrm{C}{+}^{12}\mathrm{C}$ configuration of ${}^{24}\mathrm{Mg},$ corresponding to the so-called “higher-energy molecular resonances,” is also investigated by the same MCC framework. The MCC calculation predicts the existence of three kinds of the molecular bands having $3\alpha +3\mathrm{}\alpha ,$ ${}^{12}\mathrm{C}+3\mathrm{}\alpha ,$ and ${}^{12}\mathrm{C}{+}^{12}\mathrm{C}$ structures around the excitation energy of about 40 MeV with respect to the ground state of ${}^{24}\mathrm{Mg}.$ The channel coupling among the 3α states in each ${}^{12}\mathrm{C}$ plays very important roles for the formation of the ${}^{12}\mathrm{C}+3\mathrm{}\alpha$ and $3\alpha +3\mathrm{}\alpha$ molecular bands. It is found that the populations of the ${}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}{+}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.\mathrm{}},$ ${}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}{+}^{12}\mathrm{C}{(0\mathrm{}}_2^{+}),$ and ${}^{12}\mathrm{C}{(0\mathrm{}}_2^{+}{)+}^{12}\mathrm{C}{(0\mathrm{}}_2^{+})$ channels are very small in the individual molecular bands with ${}^{12}\mathrm{C}{+}^{12}\mathrm{C},$ ${}^{12}\mathrm{C}+3\mathrm{}\alpha ,$ and $3\alpha +3\mathrm{}\alpha$ configurations, respectively. The reaction mechanism for the inelastic scattering leading to the ${}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}{+}^{12}\mathrm{C}{(0\mathrm{}}_2^{+})$ and ${}^{12}\mathrm{C}{(0\mathrm{}}_2^{+}{)+}^{12}\mathrm{C}{(0\mathrm{}}_2^{+})$ excitation channels is also investigated in relation to the obtained three kinds of the molecular bands. The result suggests that the inelastic scattering to the ${}^{12}\mathrm{C}{(0\mathrm{}}_2^{+}{)+}^{12}\mathrm{C}{(0\mathrm{}}_2^{+})$ ${[}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}{+}^{12}\mathrm{C}{(0\mathrm{}}_2^{+}\left)\right]$ channel can be interpreted in terms of weak transitions from the ${}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}{+}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}$ component of the ${}^{12}\mathrm{C}{+}^{12}\mathrm{C}$ molecular bands to the ${}^{12}\mathrm{C}{(0\mathrm{}}_2^{+}{)+}^{12}\mathrm{C}{(0\mathrm{}}_2^{+})$ ${[}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}{+}^{12}\mathrm{C}{(0\mathrm{}}_2^{+}\left)\right]$ component of the multicluster $3\alpha +3\mathrm{}\alpha$ ${(}^{12}\mathrm{C}+3\mathrm{}\alpha )$ molecular bands. All the results are discussed in connection with the band crossing model which was proposed in describing the higher-energy molecular resonance with dinuclear configuration as well as the resonances observed in the ${}^{12}\mathrm{C}{(0\mathrm{}}_2^{+}{)+}^{12}\mathrm{C}{(0\mathrm{}}_2^{+})$ and ${}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.\mathrm{}}{+}^{12}\mathrm{C}{(0\mathrm{}}_2^{+})$ exit channels.

• Received 9 May 2002

DOI:https://doi.org/10.1103/PhysRevC.66.034307