Coulomb chronometry to probe the decay mechanism of hot nuclei

Abstract

In129 Xe+ nat Sn central collisions from 8 to 25 MeV/A, the three-fragment exit channel occurs with a significant cross section. We show that these fragments arise from two successive binary splittings of a heavy composite system. The sequence of fragment production is determined. Strong Coulomb proximity effects are observed in the three-fragment final state. A comparison with Coulomb trajectory calculations shows that the time scale between the consecutive break-ups decreases with increasing bombarding energy, becoming quasi-simultaneous above excitation energy E * = 4.0±0.5 MeV/A. This transition from sequential to simultaneous break-up was interpreted as the signature of the onset of multifragmentation for the three-fragment exit channel in this system.

Post breakup dynamical evolution of fragments produced in nuclear multifragmentation

“…The situation from the experimental point of view is perhaps even more complicated, as they detect the reaction products after a time span of several orders of magnitude larger than the time scale associated with the primary fragment emission [1,4,[22][23][24][25][26][27][28]. Owing to this fact, most of the quantities observed experimentally are strongly skewed by the decay of the hot fragments produced in the stages one intends to investigate [14,16,20,21,29].…”