Rapidity Dependence of Elliptic Flow at RHIC

Abstract

The measured elliptic flow (v2) of identified particles as a function of pT and centrality at RHIC suggests the created medium in Au+Au collisions achieves early local thermal equilibrium that is followed by hydrodynamic expansion. It is not known if the eta dependence on v2 is a general feature of elliptic flow or reflects other changes in the particle spectra in going from mid-rapidity to foward rapidities. The BRAHMS experiment provides a unique capability compared to the other RHIC experiments to measure v2 for identified particles over a wide rapidity range. From Run 4 Au+Au collision at sqrt{s_{NN}} = 200GeV, identified elliptic flow is studied using the BRAHMS spectrometers, which cover 0<eta<3.4. The BRAHMS multiplicity array is used to determine the v2 event plane for the identified particle elliptic flow and to measure the pT-integrated flow for charged hadrons.