Results are presented on the production of K0S, hyperons and antihyperons in Pb--Pb and p--Be interactions at 40 GeV/c per nucleon. The enhancement pattern follows the same hierarchy as seen in the ...higher energy data--the enhancement increases with the strangeness content of the hyperons and with the centrality of collision. The centrality dependence of the Pb--Pb yields and enhancements is steeper at 40 than at 158 A GeV/c. The energy dependence of strangeness enhancements at mid-rapidity is discussed.
We present central-to-peripheral nuclear modification factors, R$_{CP}$, for the pT distributions of $K^0_s$, $\Lambda$, $\overline{\Lambda}$, and negatively charged particles, measured at central ...rapidity in Pb–Pb collisions at top SPS energy. The data cover the 55\% most central fraction of the inelastic cross section. The $K^0_s$ and $\Lambda$ R$_{CP}(pT) are similar in shape to those measured at $sqrt{^SNN}$ = 200 GeV at RHIC, though they are larger in absolute value. We have compared our $K^0_s$ RCP data to a theoretical calculation. The prediction overestimates the data at pT$\sim$3–4 GeV/c, unless sizeable parton energy loss is included in the calculation.
Results are presented on hyperon and antihyperon production in Pb–Pb, pPb and pBe collisions at 158 GeV/c per nucleon. Λ, Ξ and Ω yields have been measured at central rapidity and medium transverse ...momentum as functions of the centrality of the collision. Comparing the yields in Pb–Pb to those in pBe interactions, strangeness enhancement is observed. The enhancement increases with the centrality and with the strangeness content of the hyperons, reaching a factor of about 20 for the Ω in the central Pb–Pb collisions
A measurement of strange baryon and antibaryon production in Pb–Pb collisions has been carried out by the NA57 experiment at the CERN SPS, with 40 and 158 AGeV/c beam momentum. Results on Λ, Ξ and Ω ...hyperon yields at mid-rapidity in the most central 53% of Pb–Pb collisions at 40 AGeV/c are presented and compared with those obtained at higher energy, in the same collision centrality range.
The Λ and Ξ− yields per unit rapidity stay roughly constant while those of Ω−, Λ̄, Ξ̄+ and Ω̄+ increase when going to the higher SPS energy. Hyperon yields at the SPS are compared with those from the STAR experiment in sNN=130 GeV Au–Au collisions at RHIC.
The Na57 experiment has collected high statistics, high purity samples of K$^0_s$ and $\Lambda, \Xi $ and $\Omega$ hyperons produced in Pb-Pb collisions at 158 A GeV/c. In this paper we present a ...study of the transverse mass spectra of these particles for a sample of events corresponding to the most central 53 $\%$ of the inelastic Pb-Pb cross-section. We analyse the transverse mass distributions in the framework of the blast-wave model for the full sample and, for the first time at the SPS, as a function of the event centrality.
The production at central rapidity of K0s, Lambda, Xi and Omega particles in Pb-Pb collisions at 158 A GeV/c has been measured by the NA57 experiment over a centrality range corresponding to the most ...central 53% of the inelastic Pb-Pb cross section. In this paper we present the rapidity distribution of each particle in the central rapidity unit as a function of the event centrality. The distributions are analyzed based on hydrodynamical models of the collisions.
New results from the NA57 experiment Bruno, G E; Collaboration, the NA57
Journal of Physics G: Nuclear and Particle Physics,
08/2004, Letnik:
30, Številka:
8
Journal Article, Conference Proceeding
Results from NA57 Dainese, A.
Nuclear physics. A,
08/2006, Letnik:
774
Journal Article
Recenzirano
Odprti dostop
The NA57 experiment has measured the production of strange and multi-strange hadrons in heavy-ion collisions at the CERN SPS. After briefly introducing the NA57 apparatus and analysis procedures, we ...present recent results on strangeness enhancement in Pb+Pb relative to p+Be collisions, on the study of the
m
T
distributions of strange particles, and on central-to-peripheral nuclear modification factors in Pb+Pb collisions at top SPS energy.
In this paper we present results on transverse mass spectra and Hanbury-Brown and Twiss correlation functions of negatively charged hadrons, which are expected to be mostly negative pions, measured ...in Pb-Pb collisions at 40 A GeV/c beam momentum. Based on these data, the collision dynamics and the space-time extent of the system at the thermal freeze-out are studied over a centrality range corresponding to the most central 53% of the Pb--Pb inelastic cross section. Comparisons with freeze-out conditions of strange particles and HBT results from other experiments are discussed.
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