The 12C+12C→α+20Ne reaction mechanism and angular-momentum effects

The reaction 12C+12C→α+20Ne was studied in the energy range of 45 to 52 MeV. Energy spectra were obtained and compared. Excitation functions for the first three levels in 20Ne, recorded in the energy range of 48 to 52.2 Mev, exhibited strong fluctuations, but also average cross-sections larger than those expected by the 2I+1 rule. Angular distributions to levels up to 13.33 MeV excitation were obtained. For some states, with (8p-4h) configuration in particular, they exhibited direct-transfer characteristics. High-spin states showed spin and configuration-independent distributions. Evidence for a 10+-state in 24Mg at 39 MeV excitation is reported. It is inferred that the reaction proceeds via direct-transfer (or doorway state) and compound-nucleus mechanisms with the compound-system contribution being about 25% to 50%. The existence of critical angular momenta in the formation of the compound nucleus 24Mg is observed and discussed