A search for rare and forbidden decays of η-meson with GAMS-4π

A search for the rare and forbidden neutral decays of η-meson with the GAMS-4π setup has been performed. The charge-exchange reaction at 32.5 GeV/c was used as a source of 3.7 ṡ 106 η-mesons. At the 90% confidence level the following upper limits were obtained: B R (η → 3 γ) < 1.6 ṡ 10-4, B R (η → 4 γ) < 2.8 ṡ 10-4, B R (η → π ° π °) < 3.5 ṡ 10-4, B R (η → π ° π ° γ) < 1.7 ṡ 10-3, B R (η → π ° π ° γ γ) < 4.0 ṡ 10-3, B R (η → 3 π ° γ) < 2.4 ṡ 10-4, B R (η → 4 π °) < 2.0 ṡ 10-5. © 2006 Elsevier B.V. All rights reserved.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Observation of a spin-6 neutral meson r(2510)

In a high-statistics experiment (200 events/nanobarn) performed at the 70 GeV IHEP accelerator, a new dipion resonance has been observed in π-p collisions at 38 GeV/c momentum. The gamma-rays in reaction π-p → M0n, M0 → π0π0 → 4γ have been detected in the hodoscope spectrometer GAMS-2000. The new meson, r(2510), has a mass (2510±30) MeV/c2, a width (240±60) MeV/c2 and spin-parity J PC=6++. The production cross-section of the f, h and r mesons decreases exponentially with spin like exp [-0.9 J]. © 1984 Società Italiana di Fisica.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Beam studies of SAD-150 heavy crystal PWO calorimeter, small angle multiphoton detector of GAMS-4π spectrometer

Small Angle Detector (SAD-150) is a PbWO4 heavy crystal electromagnetic calorimeter with high energy and coordinate resolution for multiphoton events. It has been included in the GAMS-4π setup and calibrated in muon and electron beams. Test measurements of forward emitted π0 and η in the π- p charge exchange reactions with 32.5 GeV/c π- at the IHEP proton synchrotron are reported. The measured mass resolution in the η region agrees with the design value SAD-150 performance does not deteriorate with π- intensities up to 106 π-/s per cell.0SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Beam test results of a PbWO4 crystal calorimeter prototype

Beam tests of an EM-calorimeter prototype made of PbWO4 crystals, produced after significant improvement in growth technology, have been performed at the CERN SPS. The measured energy resolution is σE/E = 2.8%/√E ⊕ 0.47%. © 1995.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

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

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

Evidence for a 1.9 GeV meson decaying into ηη′

Evidence for a new meson decaying into ηη′ has been found in 38 GeV π-p charge-exchange interactions. The mass and the width of this meson are (1917 ± 15) MeV and (90-50+35) MeV, respectively. Possible spin and parity assignments are JPC = 0++, 1-+ or 2++, isospin and G-parity are IG = 0+. The t-dependence of the differential cross section follows an exponential behaviour exp(bt with a small slope: b = (2±1) (GeV/c)-2.Upper limits on its decay into ππ, ηη and KK exotic interpretation of this meson. © 1989.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Hodoscope gamma spectrometer gams-200

A 208 channel hodoscope γ spectrometer, the cells of which are made of lead-glass, is described. This detector makes it possible to measure simultaneously the coordinates (with an accuracy of 1.5 mm), and energy (to a few percent) of a large number of gammas and to reconstruct the mass and momentum of the particles decaying into gammas. The characteristics of the spectrometer have been studied in an electron beam and also under the conditions of real experiments (π0 → 2γ). © 1981.SCOPUS: ar.jinfo:eu-repo/semantics/publishe

Observation of an exotic meson with mass 1.9 GeV wich decays by the channel η′η

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

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

Study of ωω systems produced in 38 GeV/c π- p collisions

The π- p→ωωn reaction has studied for the first time at the 70 GeV IHEP accelerator. The six photons from the decay of the two ω mesons were detected in GAMS-2000, a hodoscope multi-photon spectometer. Two resonances decaying into ωω,X (1640) and X(1960), have been observed. Their quantum numbers are JPC=2++, IG=0+. The reaction is dominated by the one-pion exchange mechanism. The production cross sections σ. BR(X→ωω) are 0.65±0.15 μb and 1.0±0.2 μb, respectively. © 1989.SCOPUS: ar.jinfo:eu-repo/semantics/publishe