Source chaoticity in relativistic heavy ion collisions at SPS and RHIC

We investigate degree of coherence of pion sources produced in relativistic heavy ion collisions using multi-particle interferometry. In order to obtain ''true'' chaoticity, lambdatrue from two-pion correlation functions measured in experiments, we make a correction for long-lived resonance decay contributions. Using this lambdatrue and the weight factor which are obtained from parameter fitted to two- and three-pion correlation function, we calculate a chaotic fraction e and the number of coherent sources alpha for different colliding energies. The result gives constraints on the source and s...