Full disassembly of excited $^{24}$Mg into six $\alpha$ particles
Résumé
The decay of an excited Mg24 nucleus into six α particles is studied, from a selection of central C12+C12 reactions at 95 MeV beam energy, measured with the GARFIELD-RCo apparatus. Kinematic correlations among the detected α particles allow investigating the decay mechanism leading to the full disassembly of Mg24 into α particles. Experimental data indicate that the decay proceeds through intermediate doorway states involving excited states of C12 and Be8, with an important branching ratio estimated to be of the order of 40%. The possibility of a simultaneous breakup of the hot source in three bodies (α, Be8, C12) is excluded in favor of a sequential emission. This is confirmed by comparison with statistical model predictions, where the emission of Be8 in both its ground state and first excited state is considered. Residual differences with respect to the statistical model are observed, particularly in the branching ratio of the Hoyle state with respect to higher excitation energy C12 states.