Density in a relativistic heavy ion model system consisting of two freely interpenetrating nuclei

The relativistic determination of the density in a heavy ion model system consisting of two freely interpenetrating nuclei is presented. It is pointed out that the density becomes beam-energy-dependent and, thus, is increased beyond the sum of the rest densities of projectile and target. It is shown that the nonrelativistic density 2rhosub(0) (where rhosub(0) is the proper particle number density of matter moving with a definite Minkowskian velocity) will be enlarged by a growth rate of 0.7rhosub(0) per GeV/nucleon increase in beam energy