Particle-particle correlations and lifetimes of composite nuclei: New tests for the evaporation model and for statistical equilibration

We present data for small-angle particle-particle correlations from the reactions 80, 140, 215, and 250 MeV ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ ${+}^{27}$Al→p-p or p-d. The main features of these data are anticorrelations for small relative momenta (≤25 MeV/c) that strengthen with increasing bombarding energy. Statistical model calculations have been performed to predict the mean lifetimes for each step of evaporative decay, and then simulate the trajectories of the particle pairs and the resulting particle correlations. This simulation accounts very well for the trends of the data and can provide an important new test for the hypothesis of equilibration on which the model is built.