Observation of Double Phi Meson Production in 400 Gev/c Proton-Nucleon Interactions.

The production of pairs of (phi) mesons has been observed in 400 GeV/c proton-nucleon interactions at the Fermilab Multiparticle Spectrometer in the inclusive reaction p N (--->) (phi)(phi) + X, where each (phi) decays to a K+K-pair. A fast (200ns), high-level trigger processor was used on-line to selectively trigger on events containing two pairs of oppositely charged kaons having low invariant masses. The experimental apparatus and trigger processor are described. From a sample of 120,000 reconstructed events having at least 2 K+ and 2 K- tracks in the momentum range 5.8 (LESSTHEQ) p (LESSTHEQ) 23.0 GeV/c, the K+K-K+K-, (phi)K+K - and (phi)(phi) invariant mass spectra are presented. A total of 1503 events are identified as being consistent with (phi)(phi) production. After background subtraction and acceptance corrections, the total cross sections per nucleon for (phi)(phi) and (phi)K+K- production at 400 GeV/c are found to be (sigma)(,T)(pN( --->)(phi)(phi)+X) = 0.87 (+OR-) 0.27 (mu)b and (sigma)(,T)(pN( --->)(phi)K+K-+X) = 23.6 (+OR-) 2.7 (mu)b. An upper limit on the cross section times branching ratio for (eta)(,c) production at 400 GeV/c is established to be (sigma)(,T)(pN( --->)(eta)(,c)+X)(.)BR((eta)(,c)(--->)(phi)(phi)) (LESSTHEQ) 30 nb.