https://doi.org/10.1140/epjc/s10052-009-1019-x
Regular Article - Experimental Physics
Centrality dependence of v
2 in Au + Au at
GeV
Unidentified charged hadron v 2 with respect to the first harmonic ZDC-SMD event plane
Nuclear Science Division, Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, CA, 94720, USA
* e-mail: HMasui@lbl.gov
Received:
30
September
2008
Revised:
7
February
2009
Published online:
8
April
2009
One of the most striking results is the large elliptic flow (v
2) at RHIC. Detailed mass and transverse momentum dependence of elliptic flow are well described by ideal hydrodynamic calculations for p
T<1 GeV/c, and by parton coalescence/recombination picture for p
T=2–6 GeV/c. The systematic error on v
2 is dominated by so-called “non-flow effects”, which are correlations other than flow, such as resonance decays and jets. It is crucial to understand and reduce the systematic error from non-flow effects in order to understand the underlying collision dynamics. In this paper, we present the centrality dependence of v
2 with respect to the first harmonic event plane at ZDC-SMD (v
2{ZDC-SMD}) in Au + Au collisions at
GeV. A large rapidity gap (|Δη|>6) between midrapidity and the ZDC-SMD could enable us to minimize possible non-flow contributions. We compare the results of v
2{ZDC-SMD} with v
2{BBC}, which is measured by event plane determined at |η|=3.1–3.9. Possible non-flow contributions in those results will be discussed.
PACS: 25.75.-q – / 25.75.Ld –
© Springer-Verlag , 2009
