Abstract
A systematic study of the pre-scission timescale for relaxed processes for the system [^136]Xe + ^48 Ti is presented as a function of fragment mass asymmetry. An empirical technique is employed to obtain the excitation energy of the system from the multiplicities of the light charged particles emitted in coincidence with fragments. From these energies, pre-scission times are determined. For very hot nuclei with A [almost equal to] 180, having initial excitation energies about 3MeV/u, symmetric break up still occurs at the very end of the de-excitation chain, at an excitation energy near 100MeV. Even for completely relaxed processes, asymmetric break-up happens at an earlier stage of the particle de-excitation chain than symmetric fission. The greater the fragment mass asymmetry, the earlier in the de-excitation stage the scission occurs. For symmetric fission, the time to scission is 1 x 10^-20 seconds. For the most asymmetric break up observed here the time to scission is 0.3 to 1 x 10^-21 seconds. Completely relaxed 3-body processes are observed for our system. The bulk of such processes are found to proceed via a deep-inelastic collision followed by a sequential fission. For our 2-body events, an average IMF multiplicity near 1 is determined.
Gui, Mei (1992). Pre-scission times as a function of fragment mass asymmetry. Texas A&M University. Texas A&M University. Libraries. Available electronically from
https : / /hdl .handle .net /1969 .1 /DISSERTATIONS -1307071.