The choice of colliding-beam energy for polarized DY physics is important since the
cross sections are small and the region in which large polarization
effects are most likely to be observed is 
. The region,
is inaccessible due to the steeply falling structure function 
.
Optimization of the collision energy can be accomplished by reducing the DY cross section,
to the scaling form,
From Appendix A one sees that the
acceptance of a spectrometer depends only on 
and 
. This means that
may be measured with roughly equal acceptance at 
,
or 
, 
; however, from Eq. 2
the cross section at 
will be 16 times larger.
Finally, the luminosity of RHIC for pp collisions is expected to scale as 
.
Thus, the event rate,
