Equilibration in heavy ion collisions studied via dynamical fluctuations

A novel method to study fluctuations in distributions of reaction products has been applied to investigate the process of chemical and thermal equilib ration of nuclear matter in Ru+Ru reaction at 1.69 A GeV. The analysed data were obtained with the FOPI detector. Nontrivial fluctuations of the chemi cal composition and of transverse momenta, and their dependence on centrali ty were studied. Fluctuations of pion multiplicity were found to decrease w ith increasing centrality. This kind of dependence is less evident in the c ase of proton transversal momentum fluctuations.