@article{discovery131907,
           title = {Production of Xc1 and Xc2 in pp(overbar) collisions at (square root)s = 1.8 TeV},
          volume = {86},
           month = {April},
           pages = {3963 -- 3968},
         journal = {Physical Review Letters},
            year = {2001},
          number = {18},
            note = {{\copyright} 2001 The American Physical Society},
             url = {http://dx.doi.org/10.1103/PhysRevLett.86.3963},
        abstract = {We have measured the ratio of prompt production rates of the charmonium states {\ensuremath{\chi}}c1 and {\ensuremath{\chi}}c2 in 110pb-1 of pp? collisions at {$\sqrt$}s = 1.8TeV. The photon from their decay into J/{\ensuremath{\psi}}{\ensuremath{\gamma}} is reconstructed through conversion into e+e- pairs. The energy resolution this technique provides makes the resolution of the two states possible. We find the ratio of production cross sections {\ensuremath{\sigma}}{\ensuremath{\chi}}c2/{\ensuremath{\sigma}}{\ensuremath{\chi}}c1 = 0.96{$\pm$}0.27(stat){$\pm$}0.11(syst) for events with pT(J/{\ensuremath{\psi}}){\ensuremath{>}}4.0GeV/c, {\ensuremath{|}}{\ensuremath{\eta}}(J/{\ensuremath{\psi}}){\ensuremath{|}}{\ensuremath{<}}0.6, and pT({\ensuremath{\gamma}}){\ensuremath{>}}1.0GeV/c.},
        keywords = {Elementary Particle Physics, production},
          author = {Cerrito, L and Lancaster, M and Lane, JB and McGivern, D and Snihur, R and Waters, DS and Wyatt, AC},
            issn = {0031-9007}
}