Probing onset of nuclear vaporisation in heavy-ion collisions

The onset of nuclear vaporisation in heavy-ion collisions is examined in the present study. For this, we perform quantum molecular dynamics (QMD) model calculations supplemented with a clusterisation algorithm for fragment identification, namely the Simulated Annealing Clusterization algorithm (SACA) approach. Our results with the very sophisticated SACA method show a good agreement with the experimental findings of vaporisation (predicted by the asymptotic behaviour of the average fragment charge) in O-16 + Br-80 and O-16 + Ag-107 collisions. Further, we predicted the energy of the onset of vaporisation for Ca-40 + Ca-40, Kr-84 + Kr-84, Xe-132 + Xe-132 and Au-197 + Au-197 collisions by investigating the gas/liquid content and probability of vaporisation (and its derivative) versus the incident energy behaviour. These two observables probe the critical point of nuclear vaporisation in an extremely sophisticated manner, relative to an average fragment charge. Our findings on these two novel variables to predict the energy of the onset of vaporisation is verifiable in experiments. The influence of the colliding geometry as well as the role of Coulomb interactions are also studied to understand the system size effects on nuclear vaporisation.