EMISSION ORDER OF LIGHT PARTICLES AND LIGHT FRAGMENTS FROM HOT NUCLEIFOLLOWED BY BINARY FISSION

Emission orders of light charged particles and Li fragments from highl y excited fissioning nuclei in the reaction of Ar-40+Au-197 at E-beam/ A=25 MeV have been studied by measuring difference velocity distributi ons of two correlated particles at small relative angles in coincidenc e with two fission fragments. By comparing the data with three-body tr ajectory calculations, we found that high velocity deuterons are emitt ed prior to high velocity Li fragments but low velocity deuterons are emitted after low velocity Li fragments. On the other hand, no prefere ntial emission was observed among light particles, such as protons and deuterons. Furthermore, the emission orders are found to depend only weakly on the mass asymmetry of fission fragments.