Emission time scale and emission mechanism of intermediate mass fragments for 40Ar + 159Tb reaction at 30 MeV/nucleon

Fragment-fragment correlation functions have been measured for 40Ar + 159Tb collisions at E/A = 30 MeV. Emission time of intermediate mass fragments has been extracted from correlation functions using the three-body trajectory model. the average emission time varies with the energy of fragments. It decreases from about 500 fm/c for low energy fragments to about 100 fm/c for energetic fragments. The emission time also decreases with increasing beam energy, which implies the emission mechanism of fragments translates from sequential binary decay to multifragmentation disassembly. The transitional beam energies are about 35-45 MeV/nucleon for 40Ar + 159Tb collisions