What is the time of particle production in hadronic collisions?

Formation time of final state particles in hadronic collisions is studied in a very simple model which contains the formation time as a free parameter to be determined by comparison of calculated Bose-Einstein correlation functions with the available data. Final state pions are either products of resonance decays or are 'directly' produced. The 'direct' production is simulated by an immediate decay of a resonance. For 'direct pions' forming about a half of final state pions and for formation times of resonances within the interval 0,2-0,4 fm/c we get density of sources which leads to Bose-Einstein correlations of two identical pions consistent with recent data. The formation time of 0,2 to 0,4 fm/c is shorter then expected and it may have consequences for construction of models of proton-nucleus and nucleus-nucleus interactions. (author)