Prompt photon production with a polarized deuteron target

Predictions are presented of the polarization asymmetry in prompt photon production at large transverse momentum in the scattering of longitudinally polarized protons from longitudinally polarized deuteron targets. Data would provide important constraints on the polarization asymmetry of the gluon density in a nucleon. The experiments could take advantage of recent advances in the technology of polarized ${}_{}{}^6{}_{}{}^{}\mathrm{Li}$D.