Observation of fast collinear partitioning of the 197Au + 197Au system into three and four fragments of comparable size

Collisions of a very heavy nonfusing nuclear system Au-197 + Au-197 were studied at an energy of 15 MeV/nucleon. An interesting process of violent reseparation of this heavy system into three or four fragments of comparable size was observed. In the case of ternary partitioning, either the projectile-like fragment (PLF) or target-like fragment (TLF) breaks up almost collinearly with the PLF-TLF separation axis. In the case of quaternary reactions, both PLF and TLF were observed breaking up along this direction. By comparison with a dynamical model of deep inelastic collisions it was concluded that the ternary and quaternary reactions occur in semiperipheral collisions, in a range of angular momenta corresponding to about 0.5-0.7 of the maximum L value for grazing collisions. The time elapsing from the scission of the binary PLF + TLF system to the secondary scission of PLF or TLF was estimated to be of about 70-80 fm/c for the ternary reactions and 80-100 fm/c for the quaternary reactions.