  The sensititivity of various future polarization experiments to the first
moment Delta g of the polarized gluon density is elucidated in detail. It is
shown to what extent the first moment can be extracted from the future data as
compared to the higher moments. We concentrate on two processes which in the
near future will become an important source of information on the polarized
gluon density, namely the photoproduction of open charm to be studied at CERN
(COMPASS) and SLAC and the production of direct photons at RHIC.
