We report on ${\chi }_{c1\mathrm{}}$ and ${\chi }_{c2\mathrm{}}$ production in the Feynman-x range $0.1<\mathrm{}{x}_F<0.8\mathrm{}$ in $515\mathrm{GeV}/c$ ${\pi }^{-}\mathrm{Be}$ collisions. The ${\chi }_c$ states are observed via their radiative decays into $J/\psi$'s. The resulting photons are detected either as showers in the electromagnetic calorimeter or after conversion in the target as $e^{+}{e}^{-}$ pairs in the tracking system. The fraction of $J/\psi$ production due to ${\chi }_{c1\mathrm{}}$ and ${\chi }_{c2\mathrm{}}$ decays is $0.443\pm 0.041\pm 0.035$. The ratio of the ${\chi }_{c1\mathrm{}}$ to ${\chi }_{c2\mathrm{}}$ cross section is $0.57\pm 0.18\pm 0.06$. Our results on $J/\psi$, $\psi \left(2S\right)$, and ${\chi }_c$ production indicate that $0.454\pm 0.044\pm 0.042$ of $J/\psi$'s are produced directly.

• Received 22 May 1996

DOI:https://doi.org/10.1103/PhysRevLett.77.4294