The production of charged pions in minimum bias p+C interactions is studied using a sample of 377 000 inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The data cover a phase space area ranging from 0 to 1.8 GeV/c in transverse momentum and from -0.1 to 0.5 in Feynman x. Inclusive invariant cross sections are given on a grid of 270 bins per charge thus offering for the first time a dense coverage of the projectile hemisphere and of the cross-over region into the target fragmentation zone.

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New data on the production of protons, antiprotons and neutrons in p+p interactions are presented. The data come from a sample of 4.8 million inelastic events obtained with the NA49 detector at the CERN SPS at 158 GeV/c beam momentum. The charged baryons are identified by energy loss measurement in a large TPC tracking system. Neutrons are detected in a forward hadronic calorimeter. Inclusive invariant cross sections are obtained in intervals from 0 to 1.9 GeV/c (0 to 1.5 GeV/c) in transverse momentum and from −0.05 to 0.95 (−0.05 to 0.4) in Feynman x for protons (anti-protons), respectively. p T integrated neutron cross sections are given in the interval from 0.1 to 0.9 in Feynman x. The data are compared to a wide a

Net proton and negative hadron spectra for central Pb 1 Pb collisions at 158 GeV per nucleon at the CERN Super Proton Synchrotron were measured and compared to spectra from lighter systems. Net baryon distributions were derived from those of net protons. Stopping (rapidity shift with respect to the beam) and mean transverse momentum ͗ p T ͘ of net baryons increase with system size. The rapidity density of negative hadrons scales with the number of participant nucleons for nuclear collisions, whereas their ͗ p T ͘ is independent of system size. The ͗ p T ͘ dependence upon particle mass and system size is consistent with larger transverse flow velocity at midrapidity for Pb 1 Pb compared to S 1 S central collisions. Lattice QCD predicts that strongly interacting matter at an energy density greater than 1 2 GeV͞fm 3 attains a deconfined and approximately chirally restored state known as the quark-gluon plasma (for an overview, see [1]). This state of matter existed in the early Universe, and it may influence the dynamics of rotating neutron stars [2]. The collision of nuclei at ultrarelativistic energies offers the possibility in the laboratory of creating strongly interacting matter at sufficiently high energy density to form a quark-gluon plasma [3]. Hadronic spectra from these reactions reflect the dynamics of the hot and dense zone formed in the collision. The baryon density, established 0031-9007͞99͞82(12)͞2471(5)$15.00

We have measured the differential cross section for pp and pp elastic scattering at Vs = 53 GeV in the interval 0.5 < |/| < 4.0 (GeV/c) 2 at the CERN intersecting storage rings using the split-field magnet detector. The shape of the differential cross section differs significantly between pp and pp scattering in the region 1.1 < U| < 1.5 (GeV/c) 2 , with pp data showing a less pronounced dip structure than pp data.