5 research outputs found
Omega and AntiOmega production in Pb+Pb and p+p collisions at 30, 40 and 158 AGeV
We report preliminary results on Omega and AntiOmega production in central
Pb+Pb collisions at 30, 40 and 158 AGeV and p + p interactions at 158 GeV. The
midrapidity AntiOmega/Omega ratio is estimated to be 0.45 +- 0.05 and 0.41 +-
0.18 for central Pb+Pb collisions at 158 and 40 AGeV, respectively. The
corresponding value for 158 GeV p+p interactions is 0.67 +- 0.62. For central
Pb+Pb collisions at 158 AGeV fully corrected distributions are obtained. The
inverse slope parameters of the transverse mass spectrum and total yields are
T(Omega) = 276 +- 23 MeV, = 0.47 +- 0.07 and T(AntiOmega) = 285 +- 39
MeV, = 0.15 +- 0.02.Comment: Contribution to the proceedings of "Strangeness in Quark Matter 2003"
(March 2003, Atlantic Beach NC, USA), to be published in Journal of Physics
G., 6 pages, 6 figure
Centrality and dE_{T}/d\etadN_{ch}/d\eta$ in Heavy Ion Collisions at Mid-Rapidity
The PHENIX experiment at RHIC has measured transverse energy and charged
particle multiplicity at mid-rapidity in Au + Au collisions at
= 19.6, 130, 62.4 and 200 GeV as a function of centrality. The presented
results are compared to measurements from other RHIC experiments, and
experiments at lower energies. The dependence of
and per pair of participants is consistent with logarithmic
scaling for the most central events. The centrality dependence of
and is similar at all measured incident
energies. At RHIC energies the ratio of transverse energy per charged particle
was found independent of centrality and growing slowly with . A
survey of comparisons between the data and available theoretical models is also
presented.Comment: Proccedings of the Workshop: Focus on Multiplcity at Bari, Italy,
June 17-19,2004. To be submitted to the Jornal of Physics, "Conference
series". Includes: 20 Pages, 15 figures, 3 Tables, 80 Referencie
Strangeness from 20 AGeV to 158 AGeV
New results from the energy scan programme of NA49, in particular kaon
production at 30 AGeV and phi production at 40 and 80 AGeV are presented. The
K+/pi+ ratio shows a pronounced maximum at 30 AGeV; the kaon slope parameters
are constant at SPS energies. Both findings support the scenario of a phase
transition at about 30 AGeV beam energy. The phi/pi ratio increases smoothly
with beam energy, showing an energy dependence similar to K-/pi-. The measured
particle yields can be reproduced by a hadron gas model, with chemical
freeze-out parameters on a smooth curve in the T-muB plane. The transverse
spectra can be understood as resulting from a rapidly expanding, locally
equilibrated source. No evidence for an earlier kinetic decoupling of heavy
hyperons is found.Comment: Contribution to the proceedings of "Strangeness in Quark Matter 2003"
(March 2003, Atlantic Beach NC, USA), to be published in Journal of Physics
G. 11 pages, 14 figure
Lambda production in central Pb+Pb collisions at CERN-SPS energies
In this paper we present recent results from the NA49 experiment for
and hyperons produced in central Pb+Pb collisions at
40, 80 and 158 AGeV. Transverse mass spectra and rapidity distributions
for are shown for all three energies. The shape of the rapidity
distribution becomes flatter with increasing beam energy. The multiplicities at
mid-rapidity as well as the total yields are studied as a function of collision
energy including AGS measurements. The ratio at mid-rapidity and
in 4 has a maximum around 40 AGeV. In addition,
rapidity distributions have been measured at 40 and 80 AGeV, which
allows to study the / ratio.Comment: SQM proceedings. J. Phys. G: Nucl. Part. Phys.: submitte
Production of multi-strange hyperons and strange resonances in the NA49 experiment
The NA49 large-acceptance hadron spectrometer has measured strange and multi-strange hadrons from Pb + Pb and p + p collisions at the CERN SPS. Preliminary results for the transverse mass and rapidity distributions for - and + from central Pb + Pb collisions at 158 GeV c-1/nucleon are presented. Fully integrated yields per event of 4.42± 0.31 and 0.74± 0.04 are found for - and +, respectively, leading to a 4π +/- ratio of 0.17± 0.02. The ratio +/- at mid-rapidity is found to be 0.22 ± 0.04, agreeing with previously published values. In addition, preliminary data on the ∧(1520) and φ(1020) resonances are presented. The ∧(1520) multiplicity for p + p collisions is found to be 0.012 ± 0.003. No signal is observed for Pb + Pb collisions and a production upper limit of 1.36 ∧(1520) per event indicates an apparent suppression when comparing with scaled p + p data. Integrated φ(1020) yields per event are found to be 7.6 ± 1.1 for Pb + Pb and 0.012 ± 0.0015 for p + p collisions. No significant shift or broadening of the φ(1020) invariant mass distribution is observed in central Pb + Pb collisions. © 2001 IOP Publishing Ltd