Hadroproduction of the<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>χ</mml:mi></mml:mrow><mml:mrow><mml:mn>1</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>and<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>χ</mml:mi></mml:mrow><mml:mrow><mml:mn>2</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>states of charmonium in 800-<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mi mathvariant="normal">GeV</mml:mi><mml:mo>/</mml:mo><mml:mi>c</mml:mi></mml:math>proton-silicon interactions

The cross sections for the hadroproduction of the ${\ensuremath{\chi}}_{1}$ and ${\ensuremath{\chi}}_{2}$ states of charmonium in proton-silicon collisions at $\sqrt{s}=38.8$ GeV have been measured in Fermilab fixed target experiment 771. The \ensuremath{\chi} states were observed via their radiative decay to $J/\ensuremath{\psi}\ensuremath{\gamma},$ where the photon converted to ${e}^{+}{e}^{\ensuremath{-}}$ in the material of the spectrometer. The estimated values for the ${\ensuremath{\chi}}_{1}$ and ${\ensuremath{\chi}}_{2}$ cross sections for ${x}_{F}&gt;0$ are $263\ifmmode\pm\else\textpm\fi{}69(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}32(\mathrm{syst})$ and $498\ifmmode\pm\else\textpm\fi{}143(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}67(\mathrm{syst})$ nb per nucleon, respectively. The resulting $\ensuremath{\sigma}({\ensuremath{\chi}}_{1})/\ensuremath{\sigma}({\ensuremath{\chi}}_{2})$ ratio of $0.53\ifmmode\pm\else\textpm\fi{}0.20(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}0.07(\mathrm{syst}),$ although somewhat larger than most theoretical expectations, can be accommodated by the latest theoretical estimates.