Lee Stuart Barnby

Multiplicity Distribution and Spectra of Negatively Charged Hadrons in Au+Au Collisions at

The minimum-bias multiplicity distribution and the transverse momentum and pseudorapidity distributions for central collisions have been measured for negative hadrons ( h(-)) in Au+Au interactions at square root of ([s(NN)]) = 130 GeV. The multiplicity density at midrapidity for the 5% most central interactions is dN(h(-))/d(eta)/(eta = 0) = 280+/-1(stat)+/-20(syst), an increase per participant of 38% relative to pp collisions at the same energy. The mean transverse momentum is 0.508+/-0.012 GeV/c and is larger than in central Pb+Pb collisions at lower energies. The scaling of the h(-) yield per participant is a strong function of p( perpendicular). The pseudorapidity distribution is almost constant within /eta/<1.

An overview of results from the solenoidal tracker at RHIC experiment

The solenoidal tracker at RHIC (STAR) is a large acceptance experiment which has recorded data from a variety of collision systems, from p+p to Au+Au, at energies up to 200 GeV per nucleon. The analysis of these data has enabled STAR to study many interesting aspects of the evolution of the system formed by a heavy-ion collision. Measurements of strange particle production will be presented addressing the dependence of strangeness production on collision geometry. Heavy flavour production, including both quarkonia and open charm, has also been investigated. A particular strength of STAR is the ability to combine various detectors enabling measurements of moderate to high-pT-triggered correlations to be made and extended to include a variety of trigger types. These reveal a coupling of the medium and the jet-like components from which it may eventually be possible to infer some characteristics of the medium.

Scaling Properties of Hyperon Production in Au+Au Collisions at {radical}(s{sub NN})=200 GeV

We present the scaling properties of Lambda, Xi, and Omega in midrapidity Au+Au collisions at the Brookhaven National Laboratory Relativistic Heavy Ion Collider at sqrt[s_{NN}]=200 GeV. The yield of multistrange baryons per participant nucleon increases from peripheral to central collisions more rapidly than that of Lambda, indicating an increase of the strange-quark density of the matter produced. The strange phase-space occupancy factor gamma_{s} approaches unity for the most central collisions. Moreover, the nuclear modification factors of p, Lambda, and Xi are consistent with each other for 2<p_{T}<5 GeV/c in agreement with a scenario of hadron formation from constituent quark degrees of freedom.

{delta}{phi}{delta}{eta} correlations in central Au+Au collisions at {radical}(s{sub NN})=200 GeV

We report charged particle pair correlation analyses in the space of Δϕ (azimuth) and Δη (pseudorapidity), for central Au+Au collisions at √sNN=200 GeV in the STAR detector. The analysis involves unlike-sign charged pairs and like-sign charged pairs, which are transformed into charge-dependent (CD) signals and charge-independent (CI) signals. We present detailed parametrizations of the data. A model featuring dense gluonic hot spots as first proposed by Van Hove predicts that the observables under investigation would have sensitivity to such a substructure should it occur, and the model also motivates selection of transverse momenta in the range 0.8

Directed flow in Au+Au collisions at {radical}(s{sub NN})=62.4 GeV

We present the directed flow (v(1)) measured in Au+Au collisions at root s(NN)=62.4 GeV in the midpseudorapidity region parallel to eta parallel to < 1.3 and in the forward pseudorapidity region 2.5 <parallel to eta parallel to < 4.0. The results are obtained using the three-particle cumulant method, the event plane method with mixed harmonics, and for the first time at the Relativistic Heavy Ion Collider, the standard method with the event plane reconstructed from spectator neutrons. Results from all three methods are in good agreement. Over the pseudorapidity range studied, charged particle directed flow is in the direction opposite to that of fragmentation neutrons.

Multiplicity and Pseudorapidity Distributions of Photons in Au+Au Collisions at {radical}(s{sub NN})=62.4 GeV

We present the first measurement of multiplicity and pseudorapidity distributions of photons in the pseudorapidity region 2.3

Pion interferometry in Au+Au collisions at {radical}(s{sub NN})=200 GeV

\le

Yields and elliptic flow of

\eta