TEMPERATURES AND EXCITATION-ENERGIES OF HOT NUCLEI IN THE REACTIONS OF AR-40-NAT, BI-209 AT 25 MEV(AG)U/

Coincidence measurements of fission fragments and light-charged partic les have been performed for the reactions of Ar-40+Ag-nat, Bi-209 at E /A = 25 MeV using 4 PPAC and 11 sets of Delta E - E telescopes. Angula r correlations of fission fragments are plotted as a function of the f olding angle between the two detected fission fragments. The linear mo mentum transfer distributions are derived by measured angular correlat ion, The backward spectra of light particles detected in coincidence w ith fission fragments having different average [LMT] are analyzed with a Maxwell distribution. After some corrections the initial temperatur e of the hot nuclei is determined from the energy spectra, The excitat ion energies corresponding to the different average [LMT] are obtained considering the reaction Q values and pre-equilibration emission. In the central collision of the Ar-40+Ag-nat, Bi-209 reactions, excitatio n energies are measured to be about 4.2 MeV/u, 2.4 MeV/u and temperatu res about 6.1 MeV, 5.5 MeV, respectively. In a semi-central collision, the measured excitation energies and temperatures are about 3.5 MeV/u , 1.9 MeV/u, and 5.8 MeV, 4.8 MeV, respectively.