Measurement of vn coefficients and Reaction-­Plane Correlations in ATLAS

Hadron correlations are important tools used to study the properties of the medium produced in relativistic heavy ion collisions. We present detailed measurements of flow harmonics $v_{2}$-$v_{6}$ via di-hadron correlations in broad $p_{T}$, $Deltaeta$ and centrality ranges using the 2010 Pb+Pb data from ATLAS. These measurements are compared to the corresponding values obtained via event-plane measurements. This result provides new insights on the origin of the long range "ridge" structure over broad $pT$ ranges. Measurements of the dipolar flow ($v_{1}$) associated with initial dipole asymmetry as function of $p_{T}$ and centrality are also presented. Finally, the results of correlations between harmonic planes of different orders measured via two-plane and three-plane correlations are also discussed.