Central collisions between nuclei at relativistic energies form a hot and dense hadronic system over a large volume. Phenomenological models, as well as QCD calculations on the lattice, predict a phase transition in nuclear matter leading to deconfinement, a state of matter in which quarks and gluons are free to move inside the entire volume of the deconfined region. This new state was given the name of Quark Gluon Plasma (QGP). Based on the conjecture that collisions of heavy nuclei at high energies can create the necessary condition of a high energy density thermalized system, a series of experiments were built to search for possible signals of QGP creation. The NA35 collaboration uses a wide acceptance apparatus at the CERN SPS which detects the majority of charged hadrons (h{sup {+-}}), and neutral strange particles produced in reactions of p, 16O and 32S projectiles at 60 and 200 GeV/nucleon lab momentum on different targets. It consists of two major tracking devices which provide the momentum measurement of the charged particles: a 2 m long streamer chamber (SC) which is placed inside a 1.5 T vertex magnet, viewed by three cameras, and a 2.5x1.5x1.0 m3 Time Projection Chamber (TPC). A set of calorimeters was used as the basic trigger device of the experiment, to select central (small impact parameter) collisions. In the data presented here, a calorimeter placed in the beam path selects near head-on collisions, i.e. events where only a small amount of energy (mostly spectator nucleon energy) was detected in an angular acceptance of less than 0.3 degrees around the beam axis. The data sample consists of three systems: S+S, S+Ag and S+Au at 200 GeV/c with trigger cross section of 3, 3.2 and 6% of the total inelastic cross section, respectively.