Direct photon production at CERN ISR, CERN collider, and Fermilab Tevatron energies

Predictions are presented for large-$p_T$ direct photon production in $\overline{p}p$ collisions at CERN ISR ($\sqrt{s}=63\mathrm{}$ GeV), CERN collider (540 GeV), and Fermilab Tevatron (1600 GeV) energies in perturbative QCD. Two sets of gluon and other parton distributions determined from deep-inelastic scattering are used. Higher-order corrections ($K$ factors) are approximately taken into account. Contributions from photon bremsstrahlung graphs and the related fractions of photon events accompanied by hadrons are presented and discussed in detail.