The validity of the compound nucleus mechanism in the ¹²C(¹⁶O, α) reaction at high energies

Abstract

Excitation functions for several discrete states in ²⁴Mg excited in the ¹²C(¹⁶O, α) reaction are studied from $\text{E(}{}^{16}\text{O}\text{) = 40}\text{MeV to}\text{150}\text{MeV}$. A Hauser-Feshbach analysis is performed for states with J^π = 0⁺ through 10⁺ and a consistent interpretation of these data is obtained in a compound nucleus model with reasonable critical angular momenta. We show that the energy dependence of the high spin selectivity is in agreement with the absence of selectivity recently reported for the ¹⁴N(¹⁴N, α) reaction at high energy. Contrary to recent speculations, no compelling evidence for preequilibrium or direct processes in ¹⁶O + ¹²C reactions is found.