Observation of double phi-meson production in 400-GeV/cproton-nucleon interactions

The production of φ-meson pairs has been observed in 400-GeV/c proton-nucleon interactions at the Fermilab multiparticle spectrometer in the inclusive reaction pN→φφ+X, where each φ decays to a $K^{+}$ $K^{\mathrm{-}}$ pair. A fast (200 nsec) high-level processor was used to selectively trigger on events containing two pairs of oppositely charged kaons having low invariant masses. The experimental apparatus and trigger processor are described. The cross section for φφ production and an upper limit for ${\eta }_c$ production are presented.