A reverse big-bang

In 1994 a CERN team succeeded in accelerating lead nuclei to the energy of 158 GeV/nucleon. In 1996 the preliminary results of the NA50 experiment shown that in high energy collisions of lead nuclei the production rate of J/Ψ mesons is half the expected value. The following year these results were confirmed and brought a more accurate value of the J/Ψ absence. This absence is the sign that quarks and gluons do not recombine as usually but form the quark-gluon plasma (quagma) that was foreseen by theorists 20 years ago. The threshold of energy density beyond which this phenomena increases sharply is about 2.8 GeV/cm3. (A.C.)