System Size and Collision Energy Dependence of ν2 for Identified Charged Hadrons at RHIC-PHENIX

The transverse momentum (pT) and centrality dependence of the azimuthal anisotropy (ν2) are measured for charged hadrons in different energies and collision species by the PHENIX experiment at RHIC. We find that ν2 divided by the participant eccentricity of the initial geometry proportionally increases with the number of participants to the 1/3 power except at small Npart in Cu+Cu at . Taking the eccentricity and quark number scaling into account, there is a universal scaling for ν2 with different energies and collision sizes. The results indicate that ν2 is determined by more than just the geometrical eccentricity. It also depends on the size of collision. We also report that both the behaviors of ν2 and pT distributions can be understood from the thermal nature of produced particles based on hydro-dynamical behavior.