Fragment Charge Correlations and Spinodal Decomposition in Finite Nuclear Systems

Enhanced production of events with almost equal-sized fragments is experimentally revealed by charge correlations in the multifragmentation of a finite nuclear system selected in ${}^{129}$Xe central collisions on ${}^{nat}$Sn. The evolution of their weight with the incident energy: 32, 39, 45, 50 AMeV, is measured.Dynamical stochastic mean field simulations performed at 32 AMeV, in which spinodal instabilities are responsible for multifragmentation, exhibit a similar enhancement of this kind of events. The above experimental observation evidences the spinodal decomposition of hot finite nuclear matter as the origin of multifragmentation in the Fermi energy regime.