C12(O16,α)Mg24Excitation Functions and Statistical-Model Calculations for High-Spin States inMg24

Abstract

High-resolution excitation functions were measured in the energy range ${E}_{\mathrm{c}.\mathrm{m}.}=19\ensuremath{-}25$ MeV for the $^{12}\mathrm{C}(^{16}\mathrm{O},\ensuremath{\alpha})$ reaction to highly excited states in $^{24}\mathrm{Mg}$ (${E}_{\mathrm{exc}}\ensuremath{\approx}13.5\ensuremath{-}17.5$ MeV). The strong, rapid observed fluctuations suggest a predominately compound-nucleus reaction mechanism. The selective population of high-spin states in $^{24}\mathrm{Mg}$ by the present reaction in contrast to the lack of such selectivity in the $^{14}\mathrm{N}(^{14}\mathrm{N},\ensuremath{\alpha})$ reaction can readily be explained by Hauser-Feshbach statistical-model calculations. A fluctuation analysis indicates coherence widths of 90-150 keV, and cross correlations were found to be small and thus compatible with a purely statistical compound-nucleus process.