Blast-wave analysis of strange particle $m_T$ spectra in Pb-Pb   collisions at the SPS
  The transverse mass spectra of high statistics, high purity samples of K0s, Lambda, Xi and Omega particles produced in Pb-Pb collisions at SPS energy have been studied in the framework of the blast-wave model. The dependence of the freeze-out parameters on particle species and event centrality is discussed. Results at 40 A GeV/c are presented here for the first time. 
G.E. Bruno (the NA57 Collaboration)