32 research outputs found

    ATLAS detector and physics performance: Technical Design Report, 1

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    χ particle production in π-p collisions at 38 GeV/c

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    The production of χ particles in the reaction π-p → χ + .has been studied near threshold. The measurements have been performed at the 70 GeV IHEP proton synchrotron using the hodoscope spectrometer GAMS-2000. The χ particles have been identified through their decay χ → J/ψ + γ, J/ψ → e+e-. In the region XF ≳0.4 the fraction of obsered J/ψ particles which is obtained via the decay of χ states is 0.44 ± 0.16. The χ longitudinal and transverse momentum distributions are similar to those obtained for J/ψ. The inclusive production cross section of χ particles (3P1 and 3P2 states) at 38 GeV/c is σXF>0 (π-p → χ + .) = (28±11) nb. © 1984.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

    Study of π-p→η′ηn in a search for glueballs

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    η′η pair production in the charge exchange reaction π-p→η′ηn has been observed and studied in a search for glueballs with the 38 GeV/c pion beam of the 70 GeV IHEP accelerator. The γ-rays from the decay η′η→4γ were detected with the hodoscope spectrometer GAMS-2000. The η′η events in the mass range from threshold up to 1.8 GeV are decays of the scalar G(1590)-meson which has been already observed in its ηη decay mode. The measured ratio of the partial widths of the G→η′η and the G → ηη decay channels is 2.7±0.8 in agreement with the value expected for glueballs. © 1984 Società Italiana di Fisica.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

    The isospin-violating decay η' → 3π0

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    In an experiment performed at the 70 GeV IHEP accelerator the rate decay η'(958) → 3π0, which violates isosoin conservation, has been observed. The six final decay gamma rays are detected in the hodoscope spectrometer GAMS-2000. The branching ratio of this decay is BR (η' → 3π0) = (1.6 ± 0.4) × 10-3. An estimate of the ratio of the masses of u and d quarks is given. © 1984.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

    Hodoscope multiphoton spectrometer GAMS-2000

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    A hodoscope γ spectrometer comprising 1536 lead-glass cells is described. This detector allows the coordinates and the energies of a large number of gammas (up to ≈ 10) to be measured simultaneously and the masses (with an accuracy of 1%) and the momenta of particles decaying into photons to be determined. The use of fast processors allows selection of events by mass, energy and momentum transfer. The procedure for a fully automatic calibration of the spectrometer in an electron beam (with ∼ 1% accuracy) and for its control during long-term physical experiments is described. © 1986.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

    Observation of a 1750 MeV narrow meson decaying into ηη

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    A narrow meson which decays into ηη is observed in 38 GeV/c π-p collisions at large momentum transfer. The experiment has been performed at the Serpukhov accelerator with the GAMS-2000 spectrometer. The mass of this new meson is (1755 ± 8) MeV, its width is less than 50 MeV. Its spin-parity is JPC=0++ or less probably 2++. © 1986.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
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