Aligned ternary partitioning of the 197Au+197Au system at 23 A MeV beam energy

Ternary partitions of the Au-197 + Au-197 system in collisions at 23 A MeV beam energy have been studied. It is observed that the mass number distribution of the lightest fragments, called intermediate mass fragments (IMF), extends up to mass numbers corresponding to partitions into three comparable fragments. The lightest IMFs of A(IMF) < 20 IMF show well known features of prompt emission originating from the interaction zone (neck) during reseparation. Heavier IMFs (of A(IMF) > 30 IMF) definitely originate from sequential (but not equilibrated) decay of the primary projectile-like fragments (PLF*) (or target- like fragments (TLF*)). The decaying system evidently keeps memory of the neck configuration and consequently the IMFs are emitted collinearly either from the neck side or from the opposite side along the separation axis (polar emission). The new intriguing process of the polar emission dominates for IMFs of A(IMF) > 50 IMF.