Measurement of reaction plane correlations in Pb-Pb collisions with the ATLAS detector

Recently flow harmonics v1 - v6 have been measured in heavy-ion collisions at the LHC. The magnitude of these coefficients and their centrality dependence suggest that they are associated with the various shape components in the initial geometry. The phases of these harmonics (reaction plane angles, Φn) are generally correlated due to the correlations between the original shape components in the initial geometry; the correlations between reaction planes might also be generated dynamically during the hydrodynamic evolution of the medium. We present first measurements of various reaction plane correlations involving Φ2 to Φ6 in Pb-Pb collisions using the ATLAS detector at the LHC. The large acceptance of the ATLAS EM calorimeters, covering 4.9<η<4.9, allows for a precise measurement of these correlations. The procedure for obtaining these correlations and the physics implication of the results are discussed.