[en] Spin correlation parameters A_LL, A_SL,A_NL, A_NO, A_SO, A_LO, andA_OL have been measured for pp→npπ⁺ at 492, 576, 643, 729, and 796 MeV over a large part of phase space, using a longitudinally polarized target and a polarized beam. Results rule out broad dibaryons in this mass range in NN ³P₂ and ³F₃; in ¹D₂ some phase variation is observed, resembling that expected of a strong inelastic threshold

[en] The ηπ^- system has been studied in the reaction π^-p→ηπ^-p at 18 GeV/c. A large asymmetry in the angular distribution is observed indicating interference between L-even and L-odd partial waves. The a₂(1320) is observed in the J^PC=2⁺⁺ wave, as is a broad enhancement between 1.2 and 1.6 GeV/c² in the 1^-+ wave. The observed phase difference between these waves shows that there is phase motion in addition to that due to a₂(1320) decay. The data can be fitted by interference between the a₂(1320) and an exotic 1^-+ resonance with M=(1370±16⁺⁵⁰_-30) MeV/c² and Γ=(385±40 ⁺⁶⁵_-105) MeV/c² . copyright 1997 The American Physical Society

[en] A cylindrical multiwire drift chamber with axial charge-division has been constructed and used in experiment E852 at Brookhaven National Laboratory. It serves as a trigger element and as a tracking device for recoil protons in π^-p interactions. We describe the chamber's design considerations, details of its construction, electronics, and performance characteristics. (orig.)

[en] Antiproton-proton annihilations at rest into 3π⁰ are analyzed in terms of π⁰π⁰ final state interactions. A J^PC=2⁺⁺ resonance at a mass of 1515±10 MeV with a width of 120±10 MeV is required to explain the data. This result is supported by previous observations made on the ππ system in anti pp and anti pn annihilations which show that the resonance has I=0. This resonance is practically degenerate in mass with the f₂' (1525) but the two resonances have very different production and decay characteristics. (orig.)

[en] The Crystal Barrel spectrometer used at LEAR, CERN to study the products of anti pp and anti pd annihilations is described. A 1380 element array of CsI crystals measures photons from the decay of π⁰, η, η' and ω mesons. A segmented drift chamber in a 1.5 T magnetic field is used to identify and measure charged particles. A fast on-line trigger on charged and neutral multiplicities and on the invariant mass of secondary particles is available. The performance of the detector is discussed. (orig.)

[en] A 3045 element lead glass calorimeter and an associated fast trigger processor have been constructed, tested and implemented in BNL experiment E852 in conjunction with the multi-particle spectrometer (MPS). Approximately, 10⁹ all-neutral and neutral plus charged triggers were recorded with this apparatus during data runs in 1994 and 1995. This paper reports on the construction, testing and performance of this lead glass calorimeter and the associated trigger processor. (orig.)

[en] The Crystal Barrel Detector has been in operation since October 1989. Results on the analysis of the annihilation of protonium at rest into three pseudoscalars is presented. The π⁰π⁰π⁰ final state confirms the existence of f₂(1520)→π⁰π⁰. In the ηη system of the π⁰ηη final state an isoscalar J^PC=0⁺⁺ resonance with a mass of 1560 MeV/c² and a width of 245 MeV/c² is observed. The identification with f₀(1590) is doubtful since the ηη' decay is not observed with the corresponding strength. Our analysis yields an upper limit for the relative branching ratio BR(f₀(1560)→ηη')/(f₀(1560)→ηη)<0.24. (orig.)

[en] A measurement of the lifetime of the Λ_c baryon photoproduced coherently of a germanium-silicon target is presented. A signal of Λ_c → ΔΚ^* → pKππ⁰ has been observed and the two different decay diagrams for this process are compared. A sample of 9 Λ_c decays give a lifetime of 1.1(+0.8-0.4)10¹³ s. (orig.)

[en] Branching ratios for antiproton-proton annihilations at rest into two mesons are given. The data were obtained at LEAR by stopping antiprotons in a liquid hydrogen target. Both charged and neutral annihilation products were detected in the Crystal Barrel detector. Representative data are presented, and their bearing on the general picture of annihilation dynamics is discussed. In addition, preliminary branching ratios for two-body radiative annihilations are given. (orig.)

[en] A partial-wave analysis of the reaction π^-p→π⁺π^- π^-p at 18 GeV/c has been performed on a data sample of 250000 events obtained by Brookhaven experiment E852. The expected J^PC=1⁺⁺a₁(1260) , 2⁺⁺a₂(1320) , and 2^-+π₂(1670) resonant states are clearly observed. The exotic J^PC=1^-+ wave produced in the natural parity exchange processes shows distinct resonancelike phase motion at about 1.6 GeV/c² in the ρπ channel. A mass-dependent fit results in a resonance mass of 1593±8⁺²⁹_-47 MeV /c² and a width of 168±20⁺¹⁵⁰_-12 MeV /c² . copyright 1998 The American Physical Society