Dynamical production of fluctuations A.Chernomoretz, M.Ison, C.Dorso, F.Gulminelli

1. Dynamical production of fluctuationsA.Chernomoretz, M.Ison, C.Dorso, F.Gulminelli We initialize a Lennard Jones system of 147 neutral atoms at equilibrium inside a confining box at different densities. When the walls are taken off, the system expands, collective flow develops, and surfaces are formed. The asymptotic size distribution is essentially dominated by the deposited energy. In the case of an initially dense system, even the early fragment recognition algorithm ECRA is incapable to recognize the asymptotic configuration: overcritical densities can in no way be considered as a freeze out. subcritical close to critical supercritical The asymptotic distributions are not determined at t=0 unless r(t=0)<<rc: freeze out is at low density At t=0, only in the most diluted case fluctuations are abnormal energy

2. A clear FO can be identified at early times and low density; fluctuations freeze as fast as mean values; after FO evaporation sets in on a longer time scale At t~40t0 the fragment formation dynamics is over: <K> as well as sk are frozen. At this freeze out time the dilution of the system is comparable to the subcritical case at t=0. Almost independent of the initial density, the asymptotic fluctuation response is essentially determined by the total energy and is close to the response of a confined system at equilibrium inside the spinodal. Secondary evaporation perturbs the picture though. Asymptotic fluctuations keep a memory of the diluted freeze out configuration and not of the initial dense one. Perspective: which kind of statistical ensemble are we facing?