Event-by-event analysis of heavy ion collisions and thermodynamical fluctuations

The event-by-event analysis of heavy ions collisions is becoming possible with advent of large acceptance detectors: it can provide dynamical information which cannot be obtained from inclusive spectra. We identify some observables which can be related to standard thermodynamical fluctuations and therefore may provide information about properties of hadronic matter at the freeze-out stage. Among those are fluctuations of ``apparent temperature'' (the $p_t$ slope), as well as the population of different bins of the pion momentum distribution.