Direct photon production in polarized hadron collisions at collider and fixed target energies

Recently determined next-to-leading order sets of polarized parton distributions are used to study large-p_T $\vec{p}\vec{p}\rightarrow \gamma+X$ at $\sqrt{s}=38, 100 and 500 GeV$. Certain conversion terms, necessary to use the above sets, are determined. It is concluded that, to distinguish between the above sets, planned RHIC experiments should be successful, in particular at c.m. photon pseudorapidity $\simeq 1$, and that a proposed HERA-$\vec{N}$ fixed target experiment should have rather large accuracy at relatively large $x_T (=2p_T/\sqrt{s})$.