System size, energy and pseudorapidity dependence of directed and elliptic flow at RHIC Original Research Article

PHOBOS measurements of elliptic flow are presented as a function of pseudorapidity, centrality, transverse momentum, energy and nuclear species. The elliptic flow in Cu-Cu is surprisingly large, particularly for the most central events. After scaling out the geometry through the use of an alternative form of eccentricity, called the participant eccentricity, which accounts for nucleon position fluctuations in the colliding nuclei, the relative magnitude of the elliptic flow in the Cu-Cu system is qualitatively similar to that measured in the Au-Au system.