Charged and strange hadron elliptic flow in Cu+Cu collisions at {radical}{ovr s} = 2.4 and 200 GeV at the STAR detector.

Journal Article · Fri Jan 01 04:00:00 EST 2010 · Physical Review, C (Nuclear Physics)

DOI:https://doi.org/10.1103/PhysRevC.81.044902· OSTI ID:1050169

Abelev, B I; Aggarwal, M M; Ahammed, Z; Alakhverdyants, A V; Alekseev, I; Bridgeman, A; Krueger, K; Spinka, H M; Underwood, D G

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 {radical}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 {radical}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 {radical}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}/{var_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}/{var_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.

• Research Organization: Argonne National Laboratory (ANL)
• Sponsoring Organization: SC; NSF; EPSRC - United Kingdom; Polish Ministry of Science and Higher Education
• DOE Contract Number: AC02-06CH11357
• OSTI ID: 1050169
• Report Number(s): ANL-HEP-PR-10-38
• Journal Information: Physical Review, C (Nuclear Physics), Journal Name: Physical Review, C (Nuclear Physics) Journal Issue: 4 Vol. 81; ISSN 0556-2813; ISSN PRVCAN
• Country of Publication: United States
• Language: ENGLISH

Related Subjects

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS
74 ATOMIC AND MOLECULAR PHYSICS
BNL
HADRONS
HEAVY IONS
HYDRODYNAMICS
ION COLLISIONS
KINETIC ENERGY
PARTICLE RAPIDITY
QUARKS
THERMALIZATION
TRANSVERSE MOMENTUM