Experiments at the CERN SPS: First Signals of Deconfinement

Heavy-ion experiments at the CERN SPS began in the mid-1980s to study nuclear matter at extreme temperatures and densities. The program started with light ions, such as oxygen and sulphur at energies of 60 $$A$$ A GeV and 200 $$A$$ A GeV, later advancing to lead ions at 158 $$A$$ A GeV. A series of experiments, employing novel detector technologies, explored various signatures of quark-gluon plasma (QGP) formation. In February 2000, the results of these experiments led CERN to announce evidence for the QGP formation [1]. Subsequently, an energy scan was conducted with lead ions from 20 $$A$$ A GeV to 158 $$A$$ A GeV, to locate the threshold of QGP creation.