ORIGIN OF COMPLEX FRAGMENTS FROM S-32-NAT REACTION AT 37.5A-CENTER-DOT-MEV(AG)

Fragment emission from collisions of S-32 with Ag-nat at 37.5 A . MeV has been studied with the 4 pi multidetector AMPHORA. Production of in termediate mass and heavy fragments as well as of light charged partic les has been measured. The total charged particle multiplicity and pol ar angular distributions have been used to select various classes of c ollisions, Analysis of angular and energy distributions of fragments a nd light particles in central collisions indicates the formation of a hot source (excitation energy of approximate to 4.4 A . MeV) with an a dditional contribution from a preequilibrium process at more forward a ngles. Azimuthal angle correlations of He-Li, Li-Li, B-B, and C-C pair s have been used as a tool to study the origin of complex fragments. D ata at backward angles are well described by considering a thermalized emitter with an angular momentum around 70 HBAR and a fragment emissi on time of the order of 200 fm/c. A microscopic approach of BNV type c onfirms these emission times and angular momenta indicating the persis tence of an incomplete fusion process responsible for the emission of complex fragments at backward angles.