Alpha particles have been measured in coincidence with both projectile-like fragments (Z=5–8) and light fragments (Z=3–4) in the reactions of 35 MeV/nucleon ${}_{}{}^{16}{}_{}{}^{}\mathrm{O}$ with ${}_{}{}^{58}{}_{}{}^{}\mathrm{Ni}$. These results provide an extension of previous systematics studying the evolution of nonequilibrium emission of α particles from reactions at 6 to 20 MeV/nucleon. Two nonequilibrium components can be identified: one consists of beam velocity α particles and the other consists of intermediate velocity α particles. Compared to lower bombarding energies, no drastic change in the reaction mechanism has been observed at the Fermi energy.

• Received 6 October 1986

DOI:https://doi.org/10.1103/PhysRevC.35.1946