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 A GeV/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 A GeV/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 − , Λ, Ξ + and Ω + increase when going to the higher SPS energy. Hyperon yields at the SPS are compared with those from the STAR experiment in √ s N N = 130 GeVAu-Au collisions at RHIC.

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This paper presents the measurement of the scattering of 172 MeV/c muons in assorted materials, including liquid hydrogen, motivated by the need to understand ionisation cooling for muon acceleration.Data are compared with predictions from the GEANT 4 simulation code and this simulation is used to deconvolute detector effects. The scattering distributions obtained are compared with the Moliere theory of multiple scattering and, in the case of liquid hydrogen, with ELMS. With the exception of ELMS, none of the models are found to provide a good description of the data. The results suggest that ionisation cooling will work better than would be predicted by GEANT 4.7.0p01.

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Abstract. The transverse mass spectra of K 0 S , Λ, Ξ and Ω particles produced in PbPb collisions at 40 A GeV/c have been studied for a sample of events corresponding to the most central 53% of the inelastic Pb-Pb cross-section. We analyze the distributions in the framework of a parameterized model inspired by hydrodynamics. The dependence of the freeze-out parameters on particle species and event centrality is discussed and comparisons with results at higher energy are shown.