12C(12C, α)20Ne excitation functions and angular distributions

Excitation functions have been measured at a laboratory angle of 5degree over an incident energy range of 18--25.5 MeV (c.m.) for the 12C(12C,α) reaction leading to about 30 levels in 20Ne (E/subx/ = 0--20 MeV). Angular distributions were measured at five energies. An Ericson fluctuation analysis yields the result that most levels are populated by a large nonstatistical reaction component. A significant compound-nuclear component is also present, with correlation widths on the order of 150--250 keV (c.m.). The energy-averaged cross sections have been compared with statistical compound-nuclear (Hauser-Feshbach) calculations. This comparison indicates the presence of a strong direct-reaction mechanism, especially for the members of the proposed 8p-4h band (at 7.196, 7.834, 9.040, and 12.16 MeV). A pronounced minimum in the excitation functions is evident at E) = 19.2 MeV, near the recently reported strong resonance in the 12C(12C,p)23Na channel. Other correlated effects also appear to be present at specific energies, but the cross correlations, calculated for the entire energy range, are largely statistical