142 research outputs found
Multiplicity distribution and spectra of negatively charged hadrons in Au+Au collisions at sqrt(s_nn) = 130 GeV
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 sqrt(s_nn) = 130 GeV. The
multiplicity density at midrapidity for the 5% most central interactions is
dNh-/deta|_{eta = 0} = 280 +- 1(stat)+- 20(syst), an increase per participant
of 38% relative to ppbar 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 pt. The pseudorapidity distribution is almost constant within
|eta|<1.Comment: 6 pages, 3 figure
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Behavior of TPC`s in a high particle flux environment
TPC`s (Time Projection Chamber) used in E-810 at the AGS (Alternating Gradient Synchrotron) were exposed to fluxes equivalent to more than 10{sup 7} minimum ionizing particles per second to find if such high fluxes cause gain changes or distortions of the electric field. Initial results of these and other tests are presented and the consequences for the RHIC (Relativistic Heavy Ion Collider) TPC-based experiments are discussed
Measurement of inclusive antiprotons from Au+Au collisions at 130 GeV
We report the first measurement of inclusive antiproton production at
mid-rapidity in Au+Au collisions at 130 GeV by the STAR experiment at RHIC. The
antiproton transverse mass distributions in the measured transverse momentum
range of 0.25 < pT < 0.95 GeV/c are found to fall less steeply for more central
collisions. The extrapolated antiproton rapidity density is found to scale
approximately with the negative hadron multiplicity density.Comment: 7 pages, 3 figure
Antideuteron and antihelion production in root(s) = 130 GeV Au+Au collisions
The first measurements of light antinucleus production in Au+Au collisions at
RHIC are reported. The observed production rates for antideuterons and
antihelions are much larger than in lower energy nucleus-nucleus collisions. A
coalescence model analysis of the yields indicates that there is little or no
increase in the antinucleon freeze-out volume compared to collisions at SPS
energy. These analyses also indicate that the antihelion freeze-out volume is
smaller than the antideuteron freeze-out volume.Comment: Submitted to Phys. Rev. Let
Identified Particle Elliptic Flow in Au+Au Collisions at GeV}
We report first results on elliptic flow of identified particles at
mid-rapidity in Au+Au collisions at GeV using the STAR
TPC at RHIC. The elliptic flow as a function of transverse momentum and
centrality differs significantly for particles of different masses. This
dependence can be accounted for in hydrodynamic models, indicating that the
system created shows a behavior consistent with collective hydrodynamical flow.
The fit to the data with a simple model gives information on the temperature
and flow velocities at freeze-out.Comment: REVTeX style include
Pion Interferometry of GeV Au+Au Collisions at RHIC
Two-pion correlation functions in Au+Au collisions at
GeV have been measured by the STAR (Solenoidal Tracker at RHIC) detector. The
source size extracted by fitting the correlations grows with event multiplicity
and decreases with transverse momentum. Anomalously large sizes or emission
durations, which have been suggested as signals of quark-gluon plasma formation
and rehadronization, are not observed. The HBT parameters display a weak energy
dependence over a broad range in .Comment: 6 pages, 3 figures; accepted to Phys Rev Lett; data tables available
at STAR web site http://www.star.bnl.gov/ Click on "Publications" in menu ba
Mid-rapidity anti-proton to proton ratio from Au+Au collisions at GeV
We report results on the ratio of mid-rapidity anti-proton to proton yields
in Au+Au collisions at \rts = 130 GeV per nucleon pair as measured by the
STAR experiment at RHIC. Within the rapidity and transverse momentum range of
and 0.4 1.0 GeV/, the ratio is essentially independent of
either transverse momentum or rapidity, with an average of for minimum bias collisions. Within errors, no
strong centrality dependence is observed. The results indicate that at this
RHIC energy, although the -\pb pair production becomes important at
mid-rapidity, a significant excess of baryons over anti-baryons is still
present.Comment: 5 pages, 3 figures, accepted by Phys. Rev. Let
d̅ and 3He̅ Production in √sNN = 130 GeV Au+Au Collisions
A report on the first measurements of light antinucleus production in Au + Au collisions at the Relativistic Heavy-Ion Collider (RHIC) was presented. The production rates for d̄ and He were observed to be much larger than in lower energy nucleus-nucleus collisions. A little or no increase in the antinucleon freeze-out volume compared to CERN Super Proton Synchrotron (SPS) energy was indicated by a coalescence model analysis. The He freeze-out volume was indicated to be smaller than the d̄ freeze-out volume
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