The reaction of ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$ with ${}_{}{}^{12}{}_{}{}^{}\mathrm{C}$ has been studied at a bombarding energy of E/A=8 MeV. Fragments ranging from lithium to titanium isotopes were detected in charged-particle detectors placed at a small forward angle (θ=11°). The coincident gamma rays were observed also and used to determine the populations of various bound excited states. The products could be generally described as either complex fragments or evaporation residues. An analysis of fragment velocities and a limited number of charged-particle coincidence events suggests that the complex fragments are emitted in a binary-decay process from the compound nucleus. The extent of statistical equilibrium of the compound nucleus was studied by analyzing the population distributions of both the complex fragments and the evaporation residues. The deduced nuclear temperatures of the complex fragments were found to be in general agreement with that expected for the compound nucleus. The observed (relative) populations of states in a typical evaporation residue were compared with predictions of a statistical evaporation code. The good agreement achieved suggests that heavy fragments with masses close to the total mass in the reaction are produced from the compound nucleus by the statistical emission of light particles, such as nucleons and alpha particles. The populations of states in nuclei with A≤35, somewhat beyond the mass range of statistical evaporation, are consistent with thermal excitation, and these nuclei must be the reaction partners of the light complex fragments. Thus, all of the detected fragments are consistent with decay of an equilibrated compound nucleus by either sequential light-particle emission or binary decay into large complex fragments.

• Received 2 November 1989

DOI:https://doi.org/10.1103/PhysRevC.41.1562