Production of direct photons and neutral mesons at large transverse momenta by<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi>π</mml:mi></mml:mrow><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi>p</mml:mi></mml:math>beams at 500 GeV/<i>c</i>

We present results from the initial run of Fermilab experiment E706. The data include incident ${\ensuremath{\pi}}^{\ensuremath{-}}$ and $p$ beams at 500 GeV/c on Be and Cu targets, and span the kinematic ranges of transverse momentum and rapidity of $3.5\ensuremath{\le}{p}_{T}\ensuremath{\le}10$ GeV/c and $\ensuremath{-}0.7\ensuremath{\le}{y}_{\mathrm{c}.\mathrm{m}.}\ensuremath{\le}0.7$, respectively. We have measured cross sections for ${\ensuremath{\pi}}^{0}$ and direct-photon production, as well as the $\frac{\ensuremath{\eta}}{{\ensuremath{\pi}}^{0}}$ production ratio. From the data on Be and Cu, we have extracted the nuclear dependence of ${\ensuremath{\pi}}^{0}$ production, parametrized as ${A}^{\ensuremath{\alpha}}$. The cross sections are compared with next-to-leading-log QCD predictions for different choices of the QCD momentum scales and several sets of parton distribution functions.