The associated phenomena of preequilibrium emission and incomplete fusion in heavy ion collisions at low impact parameter are studied in the context of inverse kinematics and of a symmetrical system. The ${}_{}{}^{40}{}_{}{}^{}\mathrm{Ar}$${+}^{13}$C, ${}_{}{}^{24}{}_{}{}^{}\mathrm{Mg}$, and ${}_{}{}^{45}{}_{}{}^{}\mathrm{Sc}$ reactions performed at ${\mathit{E}}_{\mathrm{?}}$ MeV/nucleon are discussed. Heavy fragments and light particles have been detected inclusively and exclusively. Salient features of preequilibrium and incomplete fusion are presented and discussed in the framework of theoretical models. Characteristics of nuclear species formed in incomplete fusion are studied and possible limits to fusion are examined. Various possible origins of preequilibrium emission are suggested. The ${}_{}{}^{40}{}_{}{}^{}$Ar${+}^{13}$C reaction appears to be a particular case as concerns the preequilibrium emission.

• Received 24 February 1988

DOI:https://doi.org/10.1103/PhysRevC.38.135