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

The WA97 experiment has measured the transverse mass (m(T)) spectra for neg ative hadrons (h(-)) and strange particles produced at mid-rapidity in Pb-P b collisions. The increased statistics of analysed data samples allowed us to perform a study of the spectra of K-S(0), Lambda, Xi, Omega and h(-) as a function of the collision centrality. The data, which correspond to the m ost central 40% of the total inelastic cross section? have been divided int o four centrality classes according to the estimated number of nucleons tak ing part in the collision. The mT spectra, analysed separately for each cen trality bin, exhibit only weak (less than or equal to 15%) centrality depen dence. The deviation of the Omega inverse slope from the linear dependence on the particle mass is confirmed even for the most central Pb-Pb collision s.