Multicluster configuration in highly excited states of24Mg

Abstract

The nuclear structure of ${}^{24}\mathrm{Mg}$ with ${}^{12}\mathrm{C}+3\ensuremath{\alpha}$ and $3\ensuremath{\alpha}+3\ensuremath{\alpha}$ 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 3\ensuremath{\alpha}-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 $3\ensuremath{\alpha}+3\ensuremath{\alpha},$ ${}^{12}\mathrm{C}+3\ensuremath{\alpha},$ 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 3\ensuremath{\alpha} states in each ${}^{12}\mathrm{C}$ plays very important roles for the formation of the ${}^{12}\mathrm{C}+3\ensuremath{\alpha}$ and $3\ensuremath{\alpha}+3\ensuremath{\alpha}$ molecular bands. It is found that the populations of the ${}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.}{+}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.},$ ${}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.}{+}^{12}\mathrm{C}{(0}_{2}^{+}),$ and ${}^{12}\mathrm{C}{(0}_{2}^{+}{)+}^{12}\mathrm{C}{(0}_{2}^{+})$ channels are very small in the individual molecular bands with ${}^{12}\mathrm{C}{+}^{12}\mathrm{C},$ ${}^{12}\mathrm{C}+3\ensuremath{\alpha},$ and $3\ensuremath{\alpha}+3\ensuremath{\alpha}$ configurations, respectively. The reaction mechanism for the inelastic scattering leading to the ${}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.}{+}^{12}\mathrm{C}{(0}_{2}^{+})$ and ${}^{12}\mathrm{C}{(0}_{2}^{+}{)+}^{12}\mathrm{C}{(0}_{2}^{+})$ 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 ${}^{12}\mathrm{C}{(0}_{2}^{+}{)+}^{12}\mathrm{C}{(0}_{2}^{+})$ ${[}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.}{+}^{12}\mathrm{C}{(0}_{2}^{+})]$ channel can be interpreted in terms of weak transitions from the ${}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.}{+}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.}$ component of the ${}^{12}\mathrm{C}{+}^{12}\mathrm{C}$ molecular bands to the ${}^{12}\mathrm{C}{(0}_{2}^{+}{)+}^{12}\mathrm{C}{(0}_{2}^{+})$ ${[}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.}{+}^{12}\mathrm{C}{(0}_{2}^{+})]$ component of the multicluster $3\ensuremath{\alpha}+3\ensuremath{\alpha}$ ${(}^{12}\mathrm{C}+3\ensuremath{\alpha})$ 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 ${}^{12}\mathrm{C}{(0}_{2}^{+}{)+}^{12}\mathrm{C}{(0}_{2}^{+})$ and ${}^{12}{\mathrm{C}}_{\mathrm{g}.\mathrm{s}.}{+}^{12}\mathrm{C}{(0}_{2}^{+})$ exit channels.