Temperatures and excitation energies of hot nuclei in the reactions of S32+Ag and O16+Ag at 30 MeV/nucleon

For the reactions of 30 MeV/nucleon O16 and S32 with Ag, singles and coincidence measurements have been made for heavy residues, fragments (3z14), and light charged particles (z2). Mass-velocity correlations for the residues and fragment-residue coincidences indicate that increasing residue velocities do correspond to increasing excitation energy. Excitation energies as high as 90% of those which would result from complete fusion are reached. The spectra of light particles detected in coincidence with residue groups having different average velocities are analyzed with a moving source fit. When recoil effects are properly taken into account, excellent fits to the data are obtained. From the energy spectra and multiplicities of particles emitted from a fusion-like source the initial temperatures of the primary composite nuclei are determined. The results suggest that a plateau temperature near 6.5 MeV is reached above excitation energies of 3 MeV/nucleon. The temperatures are compared to those resulting from various model calculations.