Nucleus-nucleus collisions at ultra-relativistic energies: Status and prospects

Physics with ultra-relativistic heavy ions at three different accelerators SPS at CERN and AGS and RHIC at BNL is reviewed. The physics discussed ranges from global event characteristics through direct photon production, proton-proton correlation studies to Quark Gluon Plasma (QGP) phase trasition signatures via dileptonic, photonic and hadronic signals.Invited lecture given at the International School-Workshop Relativistic Heavy-Ion Physics, Prague (Czech Republic), 19–23 September 1994.Managed by Martin Marietta Energy Systems, Inc., under contract DE-AC05-84OR21400 with the U.S. Department of Energy.In conclusion, I have indicated that the RHIC project is well underway, and that the two major experiments planned for the facility, PHENIX and STAR, are being implemented with broad capabilities to address future exciting physics issues. A strong argument can be made that European groups should join the RHIC effort even with the advent of the LHC project at CERN. Aside from covering different energy regions, the two projects are shifted in time by over five years relative to each other, and RHIC is a machine dedicated to nucleus-nucleus studies, while the LHC will be available only on a limited basis.