Transverse mass spectra of strange and multiply—strange particles in Pb—Pb collisions at 158 A GeV/ c

The WA97 experiment has measured the transverse mass ( m T) spectra for negative hadrons (h −) and strange particles produced at mid-rapidity in Pb−Pb collisions. The increased statistics of analysed data samples allowed us to perform a study of the spectra of K 0 S, Λ, Ξ, Ω and h − as a function of the centrality of the collisions. The data, which correspond to the most central 40% of the total inelastic cross section, have been divided into four centrality classes according to the estimated number of nucleons taking part in the collision. The m T spectra, analysed separately for each centrality bin, exhibit only weak (≤ 15%) centrality dependence. The deviation of the Ω inverse slope from the linear dependence on the particle mass is confirmed even for the most central Pb−Pb collisions.