Recent results on central Pb+Pb collisions from experiment NA49

In this paper we present recent results from experiment NA49 on single- and multiparticle distributions obtained for Pb+Pb collisions at 158 GeV/nucleon at the CERN SPS. NA49 aims at a complete description of the hadronic final state of nuclear collisions, which will eventually allow us to establish whether an equilibrated, deconfined state of partonic matter, the quark gluon plasma (QGP), is created in the early stages of these collisions. New experimental results regarding the evolution of the hadron source through transverse expansion to chemical and thermal freeze-out are presented. We find that the available data can be understood in terms of simple physical pictures, indicating that sufficient energy densities for QGP creation are indeed reached in the early stage of the collision. The NA49 results on particle abundances are discussed in comparison with nuclear collisions at lower energy and elementary collisions at various energies. This comparison demonstrates that simple extrapolation from these systems fails to describe the results for Pb+Pb collisions at the CERN SPS.