The First 3 Years at RHIC - an Overview

This is an overview of the results from the first 3 years of RHIC experiments. RHIC is a collider built to accelerate nuclei to center of mass energies of 200 GeV per nucleon for the study of QCD in bulk systems. The most important result so far is the observation of the suppression of high pT hadrons in central Au-Au collisions followed by the subsequent null experiment where the same suppression was not seen in deuteron - Au collisions. The observed suppression is a final state effect in which a large amount of energy is lost by the fast parton as it penetrates the medium. This observation, together with measurements of the elliptic flow, leads to the conclusion that the energy density reached is at least 10 times that of a normal nucleon. The simplest and most economical explanation of these phenomenon is that the system is a dense, locally thermalized system of unscreened color charges. (author)