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 bias lead-lead collisions at 158 A GeV/c. The measurements were performed at zero degree production angle and for a wide rapidity range. The analysis method used the full particle identification capabilities (time of flight, Cerenkov counters and hadronic calorimeter) of the spectrometer. We show K/pi and pi(-)/pi(+) ratios as a function of rapidity, as well as invariant particle production cross sections. As a particularity we observe near projectile rapidity an enhancement in the number of pi(-) with respect to pi(+).