Charged and strange hadron elliptic flow in Cu+Cu collisions at sq root(s{sub NN})=62.4 and 200 GeV

Journal Article · Thu Apr 15 00:00:00 EDT 2010 · Physical Review. C, Nuclear Physics

DOI:https://doi.org/10.1103/PHYSREVC.81.044902· OSTI ID:21388953

Abelev, B I; Betts, R R; Evdokimov, O; Garcia-Solis, E J; Hofman, D J; Hollis, R S; Iordanova, A; Kauder, K; Suarez, M C ^[1]; Aggarwal, M M; Bhati, A K; Kumar, L; Pruthi, N K ^[2]; Ahammed, Z; Chattopadhyay, S; Dutta Mazumdar, M R; Ganti, M S; Ghosh, P; Mohanty, B; Mondal, M M ^[3]

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1. University of Illinois at Chicago, Chicago, Illinois 60607 (United States)
2. Panjab University, Chandigarh 160014 (India)
3. Variable Energy Cyclotron Centre, Kolkata 700064 (India)

We present the results of an elliptic flow, v{sub 2}, analysis of Cu+Cu collisions recorded with the solenoidal tracker detector (STAR) at the BNL Relativistic Heavy Ion Collider at sq root(s{sub NN})=62.4 and 200 GeV. Elliptic flow as a function of transverse momentum, v{sub 2}(p{sub T}), is reported for different collision centralities for charged hadrons h{sup +}- and strangeness-ontaining hadrons K{sub S}{sup 0}, LAMBDA, XI, and phi in the midrapidity region |eta|<1.0. Significant reduction in systematic uncertainty of the measurement due to nonflow effects has been achieved by correlating particles at midrapidity, |eta|<1.0, with those at forward rapidity, 2.5<|eta|<4.0. We also present azimuthal correlations in p+p collisions at sq root(s)=200 GeV to help in estimating nonflow effects. To study the system-size dependence of elliptic flow, we present a detailed comparison with previously published results from Au+Au collisions at sq root(s{sub NN})=200 GeV. We observe that v{sub 2}(p{sub T}) of strange hadrons has similar scaling properties as were first observed in Au+Au collisions, that is, (i) at low transverse momenta, p{sub T}<2 GeV/c, v{sub 2} scales with transverse kinetic energy, m{sub T}-m, and (ii) at intermediate p{sub T}, 2<p{sub T}<4 GeV/c, it scales with the number of constituent quarks, n{sub q}. We have found that ideal hydrodynamic calculations fail to reproduce the centrality dependence of v{sub 2}(p{sub T}) for K{sub S}{sup 0} and LAMBDA. Eccentricity scaled v{sub 2} values, v{sub 2}/epsilon, are larger in more central collisions, suggesting stronger collective flow develops in more central collisions. The comparison with Au+Au collisions, which go further in density, shows that v{sub 2}/epsilon depends on the system size, that is, the number of participants N{sub part}. This indicates that the ideal hydrodynamic limit is not reached in Cu+Cu collisions, presumably because the assumption of thermalization is not attained.

• OSTI ID: 21388953
• Journal Information: Physical Review. C, Nuclear Physics, Vol. 81, Issue 4; Other Information: DOI: 10.1103/PhysRevC.81.044902; (c) 2010 The American Physical Society; ISSN 0556-2813
• Country of Publication: United States
• Language: English

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