Chaotic sources and percolation of strings in heavy ion collisions

The chaoticity parameter lambda of Bose-Einstein correlations is studied as a toot for analyzing the interaction between color strings in multiparticl e production at high energies. Different scenarios of this interaction lead to a different behavior of lambda with energy and atomic number of the par ticipants. Comparison to the present experimental data favors the percolati on of strings scenario. The one of its versions in which lambda shows a pec uliar dependence on the string density, very similar to the dependence of t he fractional average cluster size, looks particularly attractive.