No abstract available

[en] We describe a set of large multiwire proportional chambers used in an experiment at the CERN Super Proton Synchrotron. The sensitive area is 2320 x 2320 mm², and four detecting planes, each with different orientation, are grouped together within the same mechanical frame. The number of wires for each module is 5000. Very uniform efficiency over the whole area is achieved by means of a simple mechanical construction. The chambers were operated for a long time without any damage under high particle flux. (orig.)

[en] A set of four multiwire proportional chambers with analog readout were inserted in the calorimeter of the R704 experiment at the CERN ISR. In this experiment, charmonium (canti c) resonances were directly formed through panti p annihilation. Owing to the high hadronic background, only electromagnetic final states (e⁺e^- and γγ) were detected. Located near the maximum of the electromagnetic shower development, the stack of four chambers had as its main purpose a fine spatial localization, together with a good electron-hadron discrimination and multishower rejection in the critical few GeV region. (orig.)

[en] The planned measurement of the reaction panti p→^K+K- with special regards to the processes panti p→ΦΦ and panti p→ΦK^+K-. The experimental set-up consisting of a tracking detector, a set of multi-layered scintillation counters, a threshold Cherenkov counter to reject charged pion background, a silicon counter for the measurement of dE/dx, a ring-imaging Cherenkov counter, an electromagnetic calorimeter and a γ veto counter. (HSI)

[en] In a search for gluonic hadrons, the formation channels pp→K_SK_S, pp→ηη, pp→π⁰η and pp→π⁰π⁰ were studied in the mass range from 2.1 to 2.4 GeV using the Jetset (PS202) detector and an internal molecular hydrogen cluster jet target installed in the Low Energy Antiproton Ring (LEAR) at CERN. Cross sections for pp→K_SK_S have been obtained and limits are set on the non-observation of the ξ(2230). Conversely, we find evidence for a narrow signal in a preliminary analysis of our pp→ηη d ata consistent with a narrow ξ(2230). (orig.)

[en] Data collected in the experiment R704 at the CERN ISR are used to study the annihilation process anti pp→π⁰π⁰ at several centre-of-mass energies between 2.97 and 3.56 GeV. A total sample of 7359 events has been identified, from which cross sections and angular distributions in the interval 0< vertical strokecosθ*vertical stroke<0.5 have been measured. (orig.)

[en] The cross sections of the reactions pp → φφ, φK⁺K^- and 4K^± have been measured by the JETSET (PS202) experiment at CERN in the invariant mass range from 2.15 to 2.43 GeV/c². A spin-parity analysis of the φφ system has been performed. The absolute value of the φφ cross section and the ratios σ(φφ)/σ(φK⁺K^-), σ(φφ)/σ(4K^±) are large, in marked violation of the OZI rule. Waves of quantum numbers J^PC=2⁺⁺ give the dominant contribution near threshold. (orig.)

[en] In an experiment performed at the CERN-ISR the direct formation is observed of the chi₁ and chi₂ charmonium states in proton-antiproton annihilation. A novel technique provided excellent energy resolution together with small background and reduced systematics. The following values for the masses and total widths of the states were obtained: GAMMAsub(chi1) < 1.3 MeV (95% CL); msub(chi1) = (3511.3+-0.4+-0.4) MeV; GAMMAsub(chi2) = (2.6+1.4-1.0) MeV; msub(chi2) = (3556.9+-0.4+-0.5) MeV. First measurements of the partial widths to antiproton-proton are also reported: GAMMA(chi1 -> anti pp) = 57+-12+-11) eV and GAMMA(chi2 -> anti pp) = (233+-48+-48) eV. (orig./HSI)

[en] This experiment has been performed at the CERN Intersecting Storage Rings to study the direct formation of charmonium states in antiproton-proton annihilations. The experimental program has partly been devoted to an inclusive scan for anti pp->J/psi+X in the range 3520-3530 MeV/c². A cluster of five events has been observed in a narrow energy band, centred on the centre of gravity of the ³Psub(J) states where the ¹P₁ is expected to be. When interpreted as a new resonance, these data yield a mass m=3525.4+-0.8 MeV/c². (orig.)

[en] In the experiment R704 at the CERN Intersecting Storage Rings, the two p-wave charmonium states χ₁ and χ₂ were formed directly in proton-antiproton annihilation, and detected through the decay chain χ_j → γ + J/ψ → γ + e⁺e^-. The angular distributions of the events found are studied here. A maximum likelihood analysis shows that the χ₁ radiative transition to the J/ψ is compatible with a pure dipole. Indications of a nonzero, positive quadrupole contribution to the χ₂ radiative transition are found. Finally, it is found that the χ₂ data are consistent with the conventional assumption that a single quark radiates the photon in the transition from the χ₂ to the J/ψ. (orig.)