  In view of the recent WA98 data of $\pi^0$ spectra from central Pb+Pb
collisions at the CERN SPS, we analyze the production of neutral pions for A+A
collisions across the periodic table at $\sqrt{s}=17$ AGeV and 200 AGeV within
the framework of the parton-cascade model for relativistic heavy ion
collisions. The multiplicity of the pions (having $p_T > 0.5$ GeV) in the
central rapidity region, is seen to scale as $\sim (N_{part})^{\alpha}$, where
$N_{part}$ is the number of participating nucleons, which we have approximated
as 2A for central collisions of identical nuclei. We argue that the deviation
of $\alpha$ ($\simeq 1.2$) from unity may have its origin in the multiple
scattering suffered by the partons. We also find that the constant of
proportionality in the above scaling relation increases substantially in going
from SPS to RHIC energies. This would imply that the (semi)hard partonic
activity becomes a much cleaner signal above the soft particle production at
the higher energy of RHIC, and thus much less dependent on the (lack of)
understanding of the underlying soft physics background.
