The single inclusive prompt- 
production is the clearest signal
for accessing the gluon polarization. It is dominated by the
-gluon scattering.
In order to measure 
, both the prompt- and the
away-side jet must be detected in coincidence so that the kinematics
of the incoming partons can be approximately calculated, and in particular one
must select events with Bjorken 
of the up quark larger than 0.2-0.3
so that 
is sizable.
The gluon spectrum at 
GeV, 
GeV/c
and 
is shown in Figure 2.2 [2].
It is peaked around 0.06, starts at 0.03 and doesn't
extend much above 0.1.
This 
range is lower than the one covered in COMPASS,
and hence the two experiments will probe the gluon polarization over
complementary intervals.
The 
scale in COMPASS is set by 
and 
GeV 
;
for the high 
prompt- and jet events at RHIC the scale is
set by the prompt- or jet and about a few 100 GeV .
A potential uncertainty on the measurement comes from the role of NLO
corrections to the prompt- production as well.
These corrections were calculated for the unpolarized case and are not small.
Figure 2.2: The gluon momentum fraction covered in prompt- production.
There are some discrepancies on the reported accuracies for this measurement,
in particular concerning the study of systematic effects.
The reported accuracies range from 
[3]
to 
and less [4] at GeV.
The RHIC high luminosity option
( 
at GeV,
10 times higher than the original RHIC design luminosity)
was assumed for these estimates.
These measurement accuracies will lead to a sensitivity on 
ranging roughly from 0.15 to 0.05.
Also a precise knowledge of is essential.
In the present estimates it was assumed that
at 
with infinite precision,
while recent SMC results show still large uncertainty
on this quantity for 
.
Taking into account also this uncertainty the sensitivity on
will decrease.