Hadroproduction of theχ1andχ2states of charmonium in 800-

T. Alexopoulos,L. Antoniazzi,M. W. Arenton,H. C. Ballagh,H. H. Bingham,A. Blankman,M. M. Block, Andrew F. Boden,G. Bonomi,Z. Cao, T. Y. Chen,K. Clark,D. Cline,S. Conetti,M. Cooper,G. Corti,B. Cox,P. Creti,E. C. Dukes,C. Durandet,Valerio Elia,A. R. Erwin,L. Fortney,V. Golovatyuk,E. Gorini,F. Grancagnolo,K. Hagan,M. Haire,P. Hanlet,M. He,G. Introzzi,M. Jenkins,D. Judd,W. Kononenko,W. Kowald,K. Lau,A. Ledovskoy,G. Liguori,J. Lys,Péter Mazur,A. P. McManus,S. Misawa,G. H. Mo,C.T. Murphy,K. S. Nelson,V. Pogosyan,S. Ramachandran,J. Rhoades,W. Selove,R. P. Smith,L. Spiegel,J. Sun,S. Tokár,P. Torre,J. Trischuk,L. Turnbull,D. E. Wagoner,C. R. Wang,C. Wei,W. C. Yang,Yao N,N. J. Zhang,B. T. Zou

The cross sections for the hadroproduction of the Chi1 and Chi2 states of charmonium in proton-silicon collisions at sqrt{s}=38.8 GeV have been measured in Fermilab fixed target Experiment 771. The Chi states were observed via their radiative decay to J/psi+gamma, where the photon converted to e+e- in the material of the spectrometer. The measured values for the Chi1 and Chi2 cross sections for x_F>0 are 263+-69(stat)+-32(syst) and 498+-143(stat)+-67(syst) nb per nucleon respectively. The resulting sigma(Chi1}/sigma(Chi2) ratio of 0.53+-0.20(stat)+-0.07(syst), although somewhat larger than most theoretical expectations, can be accomodated by the latest theoretical estimates.