Integrated two particle correlation functions have been extracted from charge particle multiplicity density fluctuations in pseudorapidity space by analyzing Au+Au collision events at (√SNN) = 200GeV taken by RHIC-PHENIX. The correlation lengths as a function of the number of participants Np indicate a non monotonic increase at around Np = 100 and the corresponding energy density based on the Bjorken picture is εBjτ～ 2.5GeV·fm-2. This could be a symptom of a critical behavior.