Four alpha-particles as a final state of O-16* Quasi Projectile decay

Four alpha-particles as a final state of O-16* quasi-projectile decay produced in peripheral O-16+C-12 reactions at 130 MeV is thoroughly studied. The different decay channels leading to the four alpha-particles final state are reconstructed by carrying out an event-by-event analysis of alpha correlations in the population of intermediate Be-8 and C-12. Although small, a non negligible contribution due to Be-8(gs) evaporation is found. A comparison between predictions of an accurate Hauser-Feshbach decay code and branching ratios of the different decay channels is performed. Significant deviations are observed, among these the Hoyle state population which is considerably lower than the one predicted according to the statistical model, thus suggesting possible structure effects in the Coulomb barrier and/or in the transmission coefficients.