  The production of neutral pions and eta mesons in collisions of light,
intermediate-mass, and heavy nuclei at beam energies between 0.8 A GeV and 2.0
A GeV is discussed in the framework of a model assuming equilibrium at
hadrochemical and thermal freeze-out, respectively. From the relative particle
yields temperatures of 56-90 MeV and baryon chemical potentials of 780-675 MeV
are deduced at chemical freeze-out. Midrapidity spectra of neutral pions and
eta mesons are consistent with the obtained temperatures if, in addition, the
measured transverse expansion of the collision zone is taken into account. In
contrast to results from similar analyses of AGS and SPS data the deduced
freeze-out parameters are far below the phase boundary between a hadron gas and
a quark-gluon plasma.
