41 research outputs found
Strange Particle Production in p+p, p+Pb and Pb+Pb Interactions from NA49
Recent NA49 results on Lambda, Antilambda, Xi- and Antixi+ production in
minimum bias p+p and centrality selected p+Pb collisions at 158 GeV/c, and the
results on Lambda, Antilambda, K+ and K- production in central Pb+Pb collisions
at 40, 80 and 158 A GeV are discussed and compared with other available data.
By comparing the energy dependence of Lambda and Antilambda production at
mid-rapidity a striking similarity is observed between p+p and A+A data. This
is also seen in the energy dependence of the Lambda/pi ratio. K+/pi at
mid-rapidity is affected in a similar way, due to the associated production of
K+ together with Lambda particles. The observed yields increase faster than the
number of wounded nucleons when comparing p+Pb to p+p. As already observed in
A+A collisions, the increase is larger for multistrange than for strange
baryons and for baryons than for anti-baryons.Comment: 8 pages, 10 figures, To appear in proceedings of Strange Quark in
Matter 2001-A Flavourspace Odyssey, Frankfurt am Main, Germany, 24-29. Sept.
200
Energy dependence of kaon production in central Pb+Pb collisions
Recent results from the NA49 experiment on the energy dependence of charged
kaon production in central Pb+Pb collisions are presented. First results from
the new data at 80 AGeV beam energy are compared with those from lower and
higher energies. A difference in the energy dependence of the /
and / ratios is observed. The / ratio shows a
non-monotonic behaviour with a maximum near 40 AGeV.Comment: 8 pages, 7 figures, proceedings of talk at SQM2001, Frankfurt,
Germany, to appear in J. Phys.
Xi and AntiXi production in Pb+Pb collisions at 40 AGeV at CERN SPS
First results on the production of Xi and AntiXi hyperons in Pb+Pb
interactions at 40 AGeV are presented. The AntiXi/Xi ratio at midrapidity is
studied as a function of collision centrality. The ratio shows no significant
centrality dependence within statistical errors; it ranges from 0.07 to 0.15.
The AntiXi/Xi ratio for central Pb+Pb collisions increases strongly with the
collision energy.Comment: 6 pages, 6 figures, proceedings of SQM03, to be published in Journal
of Physics G; V2: changes in table 1 and figure
Particle Production at the SPS and the QCD Phase Diagram
Recent results of particle production in the energy regime of the CERN-SPS
are reviewed. In order to collect information on the properties of the QCD
phase diagram systematic studies of the system size and the energy dependence
of particle production in heavy ion collisions have been performed. Net-baryon
distributions and results on strangeness production are discussed. The system
size dependence of many observables can be understood in the core-corona
approach, which has implications on the possibility to use system size as a
control parameter to study different areas of the phase diagram. Recent
attempts to search for a critical point, such as multiplicity fluctuations and
the transverse mass dependence of anti-baryon/baryon ratios are reviewed.Comment: Proccedings of 26th Winter Workshop on Nuclear Dynamics, 9 pages, 7
figure
Anti-nuclei and nuclei production in Pb+Pb collisions at CERN SPS energies
We present new results on production of 3He and t obtained by the NA49
experiment in 20A, 30A, 40A and 80A GeV central Pb+Pb collisions at the CERN
SPS. Transverse mass spectra and rapidity distributions for clusters measured
over a large phase space domain are discussed. We observe a weak dependence of
the mid-rapidity t/3He ratio on collision energy at SPS. The energy dependence
of the total yield for 3He is remarkably reproduced by a statistical hadron gas
model. A gradual decrease of the coalescence parameter B3 for 3He with is observed.In addition, a measurement of the yield of anti-deuterons
in Pb+Pb reactions at SPS's top energy of = 17.2 GeV is
presented.Comment: 4 pages, 8 figures. Talk at HEP07, Manchester, July 19-25, 2007;
submitted to Journal of Physics: Conference Serie
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
Event-by-Event Fluctuations at 40, 80, and 158 AGeV/c in Pb+Au Collisions
Event-by-event fluctuations of mean pt and net charge in 40, 80, and 158
AGeV/c Pb+Au collisions are presented. The observed dynamical mean pt
fluctuations in central events of about 1 % are very similar to results from
RHIC. The centrality dependence of mean pt fluctuations at 158 AGeV/c shows a
peculiar non-monotonic pattern with respect to the extrapolation from the
fluctuations measured in p+p collisions. Dynamical net charge fluctuations
smaller than the charge conservation limit are observed. After correction for
charge conservation, the measured fluctuation signal in central events is
comparable to RHIC results.Comment: 4 pages, 6 figures, proceedings of the Quark Matter 2004, in Oakland,
USA, to be published in Journal of Physics G: Nuclear and Particle Physic
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
Centrality and Energy Dependence of Proton, Light Fragment and Hyperon Production
Recent results of the NA49 collaboration are discussed. These include the
energy dependence of stopping and the production of the light fragments t and
3He. New data on the system size dependence of hyperon production at 40A and
158AGeV are also presented.Comment: 4 pages, Quark Matter 2006 proceeding
Review of Results from the NA49 Collaboration
New results of the NA49 collaboration on strange particle production are
presented. Rapidity and transverse mass spectra as well as total multiplicities
are discussed. The study of their evolution from AGS over SPS to the highest
RHIC energy reveals a couple of interesting features. These include a sudden
change in the energy dependence of the mt-spectra and of the yields of strange
hadrons around 30 AGeV. Both are found to be difficult to be reproduced in a
hadronic scenario, but might be an indication for a phase transition to a quark
gluon plasma.Comment: 8 pages, 7 figures. Proceedings of the SQM04 conference, Capetow