Centrality Dependence of Chemical Freeze-out in Au+Au Collisions at RHIC
  We will report centrality dependence of chemical freeze-out temperature ($T_{ch}$), light quark chemical potential ($\mu_{q}$), strange quark chemical potential ($\mu_{s}$), and strangeness saturation factor ($\gamma_{s}$) in Au+Au collisions at $\sqrt{s_{NN}}$ = 130 and 200 GeV. A systematic study for combination of ratios for chemical freeze-out fit is studied and we have found small ombination dependences. The results show $\gamma_{s}$ increasing with centrality but the other parameters have less sensitivity to the centralities. 
Masashi Kaneta, Nu Xu