Centrality dependence of π^±, K^±, baryon and antibaryon production in Pb + Pb collisions at 158 A GeV

We present new results of the CERN experiment NA52 on the centrality dependence of π^±, K^±, p, d, p̄ and d̄ production yields near zero transverse momentum and at several rapidities, from 64% to 4% of the total Pb + Pb cross section. Baryon yields increase nearly linearly and K^± yields faster than linearly with the number of participating nucleons N_p. The antibaryon yields increase less than linearly with N_p, indicating absorption. The centrality and rapidity dependence of the π^-/π⁺ ratio indicates Coulomb interaction of the pions with the projectile spectator protons. Within the framework of a coalescence model the radius of the particle source has been estimated from the ratios d/p² and d̄/p̄². The source radii are similar for matter and antimatter and are found to increase with ∼N^0.30-0.36_p.