New results from NA52 on particle production in Pb-Pb collisions at 158 A GeV/c

We are presenting new results on K+/- and pi(+/-) production in minimum bia s lead-lead collisions at 158 A GeV/c. The measurements were performed at z ero degree production angle and for a wide rapidity range. The analysis met hod used the full particle identification capabilities (time of flight, Cer enkov counters and hadronic calorimeter) of the spectrometer. We show K/pi and pi(-)/pi(+) ratios as a function of rapidity, as well as invariant part icle production cross sections. As a particularity we observe near projecti le rapidity an enhancement in the number of pi(-) with respect to pi(+).