Abstract. Events with 2, 3 and 4 heavy fragments (A > 20) detected in the reactions ~~176 + l~176 at 18.7, 23.7 A" MeV and ~2~ + ~Z~ at 18.4 A' MeV were analyzed by means of an improved version of the kinematic coincidence method. The phase-space distributions prove that 3-(and possibly 4-) body events predominantly originate from a two-step mechanism and are compatible with the hypothesis of a binary deep-inelastic interaction followed by the further fissionlike decay of one (or both) of the primary fragments. The characteristics of the fission step -mass asymmetry, relative velocity, in-plane and out-of-plane angles -have been reconstructed for the 3-body events and indications are found that nonequilibrium effects at the end of the deep-inelastic phase may influence the fissionlike decay.

Events with 2, 3 and 4 heavy-fragments (A>20) have been detected in the reactions l~176 l~176 at E/A = 18.7, 23.7 MeV and 12~ t2~ at E/A= 18.4 MeV.The experiments were performed with an array of 12 detectors which together covered a large fraction of the forward hemisphere and allowed a high detection efficiency for these events. Masses and energies of all fragments have been reconstructed by means of an improved version of the kinematic coincidence method. The probabilities P~ and P4 of producing 3-and 4-body events were found to depend mainly on the dissipated energy rather than on the bombarding energy, thus indicating that their origin lies more in the decay properties of the excited fragments than in the dynamics of the interaction. Emission of light particles from the composite system is shown to become more relevant with increasing bombarding energy and may explain the drop of the P3 and P4 curves at high energy losses. Small deviations of the P3 and P4 curves at 23.7 A. MeV from those at lower bombarding energies were used to estimate the amount of a possible pre-equilibrium light particle emission as a function of impact parameter.

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Experimental and theoretical evidence is presented that the proton exchange is strongly enhanced by a mixing of single-particle configurations in 37 C1 (in the system 36 S+ 37 C1), which is shown to be the clearest example of hybridization in nuclear physics. The experimental data on elastic and inelastic transfer are only reproduced if the complete set of single-particle states (^3/2, ^1/2, fin, pyi, fsn, and pxji) is included in a coupled-reaction-channel calculation. The strong enhancement is explained by the hybridization of orbits of different parity. In a two-center molecular-orbital approach the density of the proton orbitals in the lowest state is shown to be concentrated at the center between the two 36 S cores.3"2+ 0*