Results on cascade production in lead-lead interactions from the NA57 experiment

The NA57 experiment has been designed to study the production of strange and multi-strange particles in Pb-Pb and p-Be collisions at the CERN SPS. The predecessor experiment WA97 has measured an enhanced abundance of strange particles in Pb-Pb collisions relative to p-A reactions at 160 GeV/c per nucleon beam momentum. NA57 has extended the WA97 measurements to investigate the evolution of the strangeness enhancement pattern as a function of the beam energy and over a wider centrality range. In this paper, we report results on cascade production for about the 60% most central collisions at 160 GeV/c per nucleon

Transverse mass distributions of strange particles produced in Pb-Pb collisions at 158 A GeV/c

Experiment NA57 has collected high statistics, high purity samples of $K^0_s$, $\Lambda$, $\Xi$ and $\Omega$ 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 about the most central 55% 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 under consideration and, for the first time at the SPS, as a function of the event centrality

Energy dependence of hyperon production in nucleus-nucleus collisions at SPS

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. © 2004 Elsevier B.V. All rights reserved

Study of the transverse mass spectra of strange particles in Pb-Pb collisions at 158 a GeV/c

The NA57 experiment has collected high statistics, high purity samples of KS0 and Λ, ξ and Ω 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

New results from the NA57 experiment

We report results from the experiment NA57 at CERN SPS on hyperon production at midrapidity in Pb-Pb collisions at 158 $A$ GeV/$c$ and 40 $A$ GeV/$c$. $\Lambda$, $\Xi$ and $\Omega$ yields are compared with those from the STAR experiment at the higher energy of the BNL RHIC. $\Lambda$, $\Xi$, $\Omega$\ and preliminary $K_S^0$ transverse mass spectra are presented and interpreted within the framework of a hydro-dynamical blast wave model

Hyperon production in 40 A GeV / c collisions from the NA57 experiment

Enhancements of strange baryon and anti-baryon yields were first observed in Pb-Pb interactions at 160 A GeV / c by WA97. The aim of the NA57 experiment is to investigate how these enhancements behave as a function of energy, and over a broader centrality range than that which was available with WA97. This paper presents a comparison of the hyperon yields in Pb-Pb interactions at 40 A GeV / c and 160 A GeV / c. Preliminary signals for the p-Be data at 40 A GeV / c are also shown

Strange baryon production in Pb-Pb Interactions at CERN-SPS

Recent results on strange baryons and antibaryon production in Pb-Pb collisions at 160 GeV per nucleon from the NA57 experiment are reported. Strangeness enhancements and the transverse mass spectra properties are described