We present the results obtained with the magnetic detector DM1 at the Orsay storage ring ACO for the reaction e + e − → π + π − π 0 from 483 to 1100 MeV in the center of mass. Our data show without ambiguity an interference effect between the ω and φ mesons, which corresponds to a negative coupling constant product ratio Re( g γω g ω →3 π / g γφ g φ →3 π ) ; however our measurements above the φ, performed using kinematical analysis, can only be explained by a higher energy contribution. In addition, the parameters of the ω have been obtained with an improved accuracy compared to other experiments, and particularly the branching ratio B ω →e + e − = (6.75±0.69) × 10 −5 . We confirm that the reaction e + e − → π + π − π 0 proceeds essentially via a quasi-two-body state ϱπ , at the energy of the φ.
FITTED CROSS SECTION AT OMEGA PEAK IS 1410 +- 130 NB AND AT PHI PEAK IS 615 +- 55 NB.
We present data obtained at the ISR, on the determination of the ratio R = γ π 0 at s = 30.6 GeV and we compare the results with our previous measurement at s = 53.2 GeV. The ratio R = γ π 0 integrated over the interval 0.1 ⩽ χ T ⩽ 0.2 is (1.6 ± 0.5) × 10 −2 and we obtain an indication of a universal χ T dependence.
No description provided.
Differential cross sections and polarization asymmetries for the reaction p + p → d + π + have been measured at 0.8 GeV. The data has been analyzed within the formalism of Mandl and Regge and the results are compared with the recent coupled channel calculations of Niskanen. It is concluded that at this energy the production of upto f-wave pions is important.
No description provided.
No description provided.
Inclusive energy spectra of protons, deuterons, and tritons were measured with a telescope of silicon and germanium detectors with a detection range for proton energies up to 200 MeV. Fifteen sets of data were taken using projectiles ranging from protons to Ar40 on targets from Al27 to U238 at bombarding energies from 240 MeV/nucleon to 2.1 GeV/nucleon. Particular attention was paid to the absolute normalization of the cross sections. For three previously reported reactions, He fragment cross sections have been corrected and are presented. To facilitate a comparison with theory the sum of nucleonic charges emitted as protons plus composite particles was estimated and is presented as a function of fragment energy per nucleon in the interval from 15 to 200 MeV/nucleon. For low-energy fragments at forward angles the protons account for only 25% of the nucleonic charges. The equal mass Ar40 plus Ca systems were examined in the center of mass. Here at 0.4 GeV/nucleon Ar40 plus Ca the proton spectra appear to be nearly isotropic in the center of mass over the region measured. Comparisons of some data with firestreak, cascade, and fluid dynamics models indicate a failure of the first and a fair agreement with the latter two. In addition, associated fast charged particle multiplicities (where the particles had energies larger than 25 MeV/nucleon) and azimuthal correlations were measured with an 80 counter array of plastic scintillators. It was found that the associated multiplicities were a smooth function of the total kinetic energy of the projectile. NUCLEAR REACTIONS U(Ne20,X), EA=240 MeV/nucleon; U(Ar40,X), Ca(Ar40,X), U(Ne20,X), Au(Ne20,X), Ag(Ne20,X), Al(Ne20,X), U(He4,X), Al(He4,X), EA=390 MeV/nucleon; U(Ar40,X), Ca(Ar40,X), U(Ne20,X), U(He4,X), U(p,X), EA=1.04 GeV/nucleon; U(Ne20,X), EA=2.1 GeV/nucleon; measured σ(E,θ), X=p,d,t.
No description provided.
No description provided.
No description provided.
The energy dependence of the K L 0 -K S 0 transmission regeneration amplitudes on deuterons and neutrons in the momentum region 10–50 GeV/ c is determined. The moduli of the modified transmission amplitudes are momentum dependent. These dependences are fitted by the expression A j p − nj , where A j and n j ( j = d, n) are constants: A d =2.88 ±0.04 mb , n d =0.546±0.030, for deuterons , A n =1.97 ±0.14 mb , n n =0.530±0.019, for neutrons , The amplitude phases do not depend on the kaon momentum and are equal to ϕ d = (−130.9 ± 2.7)° ϕ n = (−132.3 ± 1.7)°. The mean value of the ratio of the total cross-section differences for K 0 and K 0 interactions with neutrons and protons is determined. The residues of the partial ω and ϱ amplitudes, which contribute to the kaon-nucleon interaction amplitudes, are also obtained.
FORWARD CROSS SECTION, AMPLITUDE AND PHASE FOR K0 REGENERATION.
(AK0 - K0) TOTAL CROSS SECTION DIFFERENCES.
Cross-section values or upper limits are presented for twenty-five two-body hypercharge-exchange reactions in K − p and π + p interactions at 10 and 16 GeV/ c . The 16 GeV/ c results are compared with some predictions of line-reversal plus exchange-degenerate Regge poles, of SU(3) and of the additive quark model. Agreement is found in all cases.
No description provided.
We report on the experimental results obtained at the ISR for the η particle production at 90° and √ s = 30.6 and 53.2 GeV. We determine the invariant cross section and the p t distribution in the interval 1 ⩽ p t ⩽ 5 GeV/ c . We find that the p t distribution has the same shape of the π 0 production and differ from it by a constant factor R 90° = 0.5 ± 0.07.
No description provided.
A sample of 56 909 events of the reaction π − p→K + K − n at 10 GeV/ c has been measured in the Omega Spectrometer at CERN. In the K + K − system, besides production of mesons in the S ∗ /φ, f 0 / A 2 , g /ω ∗ and h regions we observe a new structure at 2.20 GeV with a width of the order of 200 MeV.
BREIT-WIGNER RESONANCES PLUS SMOOTH BACKGROUND FITTED TO K+ K- MASS SPECTRUM. RESTRICTIVE T-CUTS TO ENHANCE THE X(2200) GIVE CONSISTENT RESULTS.
The polarization in π + p → π + p and K + p → K + p has been measured at 6 and 12 GeV/ c in the four-momentum transfer interval 0.1 ⩽ | t | ⩽ 2.0 (GeV/ c ) 2 by scattering on protons of a polarized deuteron target. Comparison with existing results obtained with polarized proton targets shows good general agreement and no evidence for asymmetry effects due to the presence of the spectator neutron. For K + p elastic scattering polarization the experiment yields improved statistics, especially at 6 GeV/ c
No description provided.
No description provided.
No description provided.
We report the results of an experiment made at the CERN ISR to investigate the possible diret production of single photons in pp collisions at √ s = 53.2 GeV at 90° and in the p t interval 2.3 to 5.7 GeV/ c . The value of the ratio R = n γ / n π 0 is compatible with zero for low p t ⪅ 3 GeV/ c but, in spite of the large error, shows a trend to increase for larger p t .
THIS USES THE SO-CALLED D2L TRIGGER (SEE PAPER).
THIS USES THE SO-CALLED D2MAX TRIGGER (SEE PAPER).
THIS USES THE SO-CALLED D2MAX TRIGGER (SEE PAPER).
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