32 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
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
Measurement of event-by-event transverse momentum and multiplicity fluctuations using strongly intensive measures and in nucleus-nucleus collisions at the CERN Super Proton Synchrotron
Results from the NA49 experiment at the CERN SPS are presented on
event-by-event transverse momentum and multiplicity fluctuations of charged
particles, produced at forward rapidities in central Pb+Pb interactions at beam
momenta 20, 30, 40, 80, and 158 GeV/c, as well as in systems of
different size (, C+C, Si+Si, and Pb+Pb) at 158 GeV/c. This publication
extends the previous NA49 measurements of the strongly intensive measure
by a study of the recently proposed strongly intensive measures of
fluctuations and . In the explored kinematic
region transverse momentum and multiplicity fluctuations show no significant
energy dependence in the SPS energy range. However, a remarkable system size
dependence is observed for both and , with the
largest values measured in peripheral Pb+Pb interactions. The results are
compared with NA61/SHINE measurements in collisions, as well as with
predictions of the UrQMD and EPOS models.Comment: 12 pages, 14 figures, to be submitted to PR
Production of deuterium, tritium, and He in central Pb+Pb collisions at 20A, 30A, 40A, 80A, and 158A GeV at the CERN SPS
Production of , , and He nuclei in central Pb+Pb interactions was
studied at five collision energies ( 6.3, 7.6, 8.8, 12.3, and
17.3 GeV) with the NA49 detector at the CERN SPS. Transverse momentum spectra,
rapidity distributions, and particle ratios were measured. Yields are compared
to predictions of statistical models. Phase-space distributions of light nuclei
are discussed and compared to those of protons in the context of a coalescence
approach. The coalescence parameters and , as well as coalescence
radii for and He were determined as a function of transverse mass at
all energies.Comment: 22 pages, 29 figures, 8 tables, for submission to Phys. Rev.
System-size and centrality dependence of charged kaon and pion production in nucleus-nucleus collisions at 40A GeV and158A GeV beam energy
Measurements of charged pion and kaon production are presented in centrality
selected Pb+Pb collisions at 40A GeV and 158A GeV beam energy as well as in
semi-central C+C and Si+Si interactions at 40A GeV. Transverse mass spectra,
rapidity spectra and total yields are determined as a function of centrality.
The system-size and centrality dependence of relative strangeness production in
nucleus-nucleus collisions at 40A GeV and 158A GeV beam energy are derived from
the data presented here and published data for C+C and Si+Si collisions at 158A
GeV beam energy. At both energies a steep increase with centrality is observed
for small systems followed by a weak rise or even saturation for higher
centralities. This behavior is compared to calculations using transport models
(UrQMD and HSD), a percolation model and the core-corona approach.Comment: 32 pages, 14 figures, 4 tables, typo table II correcte
Production of deuterium, tritium, and He 3 in central Pb + Pb collisions at 20A, 30A, 40A, 80A, and 158A GeV at the CERN Super Proton Synchrotron
Production of d,t, and He3 nuclei in central Pb+Pb interactions was studied at five collision energies (sNN=6.3, 7.6, 8.8, 12.3, and 17.3 GeV) with the NA49 detector at the CERN Super Proton Synchrotron. Transverse momentum spectra, rapidity distributions, and particle ratios were measured. Yields are compared to predictions of statistical models. Phase-space distributions of light nuclei are discussed and compared to those of protons in the context of a coalescence approach. The coalescence parameters B2 and B3, as well as coalescence radii for d and He3 were determined as a function of transverse mass at all energies. © 2016 CERN
Measurement of event-by-event transverse momentum and multiplicity fluctuations using strongly intensive measures
Results from the NA49 experiment at the CERN Super Proton Synchrotron (SPS) are presented on event-by-event transverse momentum and multiplicity fluctuations of charged particles, produced at forward rapidities in central Pb + Pb interactions at beam momenta 20A, 30A, 40A, 80A, and 158A GeV/c, as well as in systems of different sizes (p+p, C + C, Si + Si, and Pb + Pb) at 158A GeV/c. This publication extends the previous NA49 measurements of the strongly intensive measure ΦpT by a study of the recently proposed strongly intensive measures of fluctuations Δ[PT,N] and Σ[PT,N]. In the explored kinematic region transverse momentum and multiplicity fluctuations show no significant energy dependence in the SPS energy range. However, a remarkable system size dependence is observed for both Δ[PT,N] and Σ[PT,N], with the largest values measured in peripheral Pb + Pb interactions. The results are compared with NA61/SHINE (SPS Heavy Ion and Neutrino Experiment) measurements in p+p collisions, as well as with predictions of The Ultrarelativistic Quantum Molecular Dynamics and EPOS models.United States. Department of Energy (Grant DE-FG03-97ER41020/A000
Antideuteron and deuteron production in midcentral Pb plus Pb collisions at 158A GeV
Production of deuterons and antideuterons was studied by the NA49
experiment in the 23.5% most central Pb + Pb collisions at the top CERN
Super Proton Synchroton (SPS) energy of root s(NN) = 17.3 GeV. Invariant
yields for (d) over bar and d were measured as a function of centrality
in the center-of-mass rapidity range -1.2 < y < -0.6. Results for (d)
over bar (d) together with previously published (p) over bar (p)
measurements are discussed in the context of the coalescence model. The
coalescence parameters B-2 were deduced as a function of transverse
momentum p(t) and collision centrality
Critical fluctuations of the proton density in A+A collisions at 158A GeV
We look for fluctuations expected for the QCD critical point using an intermittency analysis in the transverse momentum phase space of protons produced around midrapidity in the 12.5 % most central C+C, Si+Si and Pb+Pb collisions at the maximum SPS energy of 158A GeV. We find evidence of power-law fluctuations for the Si+Si data. The fitted power-law exponent is consistent with the value expected for critical fluctuations. Power-law fluctuations had previously also been observed in low-mass collisions. © 2015, The Author(s)