Showing papers by "Fridolin Dittus published in 1999"

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

Abstract: We present new results of the CERN experiment NA52 on the centrality dependence of π±, K±, p, d, and 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 Np The antibaryon yields increase less than linearly with Np, 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 /2 The source radii are similar for matter and antimatter and are found to increase with ~ Np030−036

Charged pion production in fixed-target Pb + Pb collisions at 158 GeV/nucleon

Abstract: Changes in pion production as a function of the impact parameter of the collision or the incident energy, may reveal characteristics of a possible first-order phase transition from nuclear to quark matter, as predicted by lattice quantum chromodynamics. In this paper we investigate charged pion production in Pb+Pb collisions at 158 GeV/nucleon near 0° production angle and at forward rapidity (4.3 y6.3). The centrality dependence of pion production is shown in the impact parameter range ~ 2-12 fm at the rapidities y = 5.7 and 6.3. An enhancement in the -/+ ratio has been measured near beam rapidity, indicating Coulomb interaction of charged pions with the spectator protons. The charged pion yield per nucleon participating in the collision (Np) at y = 5.7 increases faster than linearly with Np, up to Np~100 and then it saturates, while at y = 6.3 it does not exhibit any sudden change as a function of Np.

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

Abstract: We are presenting new results on K± and π± 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/π and π−/π+ 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 π− with respect to π+.