We have measured the differential cross section for pp and pp elastic scattering at Vs = 53 GeV in the interval 0.5 < |/| < 4.0 (GeV/c) 2 at the CERN intersecting storage rings using the split-field magnet detector. The shape of the differential cross section differs significantly between pp and pp scattering in the region 1.1 < U| < 1.5 (GeV/c) 2 , with pp data showing a less pronounced dip structure than pp data.

The multiplicities of charged secondaries in proton-proton collisions were determined using the split-field-magnet detector at the CERN Intersecting Storage Rings (ISR). Measurements are presented on multiplicity distributions both for inelastic and non-single-diffractive events at four different energies 6 =30.4, 44.5, 52.6, and 62.2 GeV. The results reported here represent the first high-statistics measurement of charged multiplicity distributions at ISR energies with a magnetic detector covering nearly the full solid angle.

We have measured the production cross-section times branching ratio for J/ψ→μ+μ- in pp̄ interactions at √s=630 GeV in the kinematic range |y| <2.0 and pT> 5 GeV/c, BR(J/ψ→μ+μ -)σ(pp̄→J/ψ)=6.18±0.24±0.81 nb. The data sample collected in 1988 and 1989 for an integrated luminosity of 4.7 pb-1 represents a fivefold improvement over the statistics in our earlier study of the J/ψ production process, and the pT distribution which is measured extends to 28 GeV/c. Using event topology we show that the rate for the direct production of J/ψ, via radiative decays of χ states, is larger than that for production via B-hadrons. Production of ψ′ is also studied using the decay modes ψ′→μ+μ- and ψ′→J/ψπ+π-

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