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 New Journal of Physics 1 (1999) 23
 Charged pion production in fixed target Pb + Pb collisions at 158 GeV per nucleon
 NA52 Collaboration(s)
 (1999)
 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 $(4.3\leq y \leq 6.3)$. 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 pi-/pi+ 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 (N_p) at y = 5.7 increases faster than linearly with N_p, up to N_p~100 and then it saturates, while at y = 6.3 it does not exhibit any sudden change as a function of N_p.
 Thème(s) : Physique/Physique des Hautes Energies - Expérience
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 in2p3-00024048, version 1 http://hal.in2p3.fr/in2p3-00024048 oai:hal.in2p3.fr:in2p3-00024048 Contributeur : Nicole Berger <> Soumis le : Lundi 18 Avril 2005, 17:15:43 Dernière modification le : Lundi 18 Avril 2005, 17:32:42