Results on hyperon production from the NA57 experiment

Recent results on hyperon production in Pb--Pb collisions from the NA57 experiment are reported. Strangeness enhancement and the transverse mass spectra properties at 158 GeV per nucleon are described.Comment: submitted to Acta Phys. Hung. A (Heavy Ion Physics

Centrality dependence of the expansion dynamics in Pb - Pb collisions at 158 A GeV/c

ABSTRACT Two-particle correlation functions of negatively charged hadrons from Pb-Pb collisions at 158 GeV c-1/nucleon have been measured by the WA97 experiment at the CERN SPS. A Coulomb correction procedure that assumes an expanding source has been implemented. Within the framework of an expanding thermalized source model the size and dynamical state of the collision fireball at freeze-out have been reconstructed as a function of the centrality of the collision. Less central collisions exhibit a different dynamics than central ones: both transverse and longitudinal expansion velocities are slower, the expansion duration is shorter and the system freezes out, showing smaller dimensions and higher temperatur

MULTIPLICITY OF CHARGED PARTICLES IN PB - PB COLLISIONS AT SPS ENERGIES

The multiplicity of charged particles in the central rapidity region has been measured by the NA57 experiment in Pb-Pb collisions at the CERN SPS at two beam momenta: 158 A GeV/c and 40 A GeV/c. The value of dN(ch)/d eta at the maximum has been determined and its behaviour as a function of centrality has been studied in the centrality range covered by NA57 (about 50% of the inelastic cross section). The multiplicity increase is compatible with a logarithmic dependence on the centre of mass energy. The results are compared with those from other experiments and with the VENUS and RQMD models

Hyperon yields in Pb - Pb collisions from NA57 experiment

ABSTRACT We report results from the experiment NA57 at CERN SPS on hyperon yields at midrapidity in Pb-Pb collisions at 158 A GeV/c and 40 A GeV/c. A, Z and R yields are compared with preliminary results from the STAR. experiment at BNL

Results on 40 A GeV/c Pb - Pb collisions from the NA57 experiment

ABSTRACT The NA57 experiment has been designed to study the onset of the strange baryon and antibaryon enhancements in Pb-Pb with respect to p-Be collisions, first observed by WA97 at 160 A GeV/c. NA57 has extended the WA97 measurements to investigate the evolution of strangeness enhancement over a wider centrality range and as a function of the beam energy. Results on hyperon production in central Pb-Pb collisions at 40 A GeV/c are presented and compared with those obtained at higher energy, in the same centrality range

First results on strange baryon production from the NA57 experiment

We briefly describe the NA57 experiment, the status of the data taking, of the event reconstruction and of the physics analysis. For the physics results, we shall keep separate the study of the 40 A GeV /c Pb-Pb data (for which the bulk of reference p-Be data are still to be collected in 2001) from the study of the enhancements as a function of the number of wounded nucleons at 160 A GeV/c. (11 refs)

Recent results from NA57 on strangeness production in p-A and Pb-Pb collisions at 40 and 158 A GeV/c

The production of hyperons in Pb-Pb and p-Be interaction at 40 $A$ GeV/$c$\ beam momentum has been measured by the NA57 experiment. Strange particle enhancements at 40 $A$ GeV/$c$ are presented and compared to those measured at 158 $A$ GeV/$c$. Their transverse mass spectra have been studied in the framework of the blast-wave model. The multiplicity of charged particles as a function of the energy is also discussed.The production of hyperons in Pb-Pb and p-Be interaction at 40 $A$ GeV/$c$\ beam momentum has been measured by the NA57 experiment. Strange particle enhancements at 40 $A$ GeV/$c$ are presented and compared to those measured at 158 $A$ GeV/$c$. Their transverse mass spectra have been studied in the framework of the blast-wave model. The multiplicity of charged particles as a function of the energy is also discussed