The single-pion production reactions $pp\to d\pi^+$, $pp\to np\pi^+$ and $pp\to pp\pi^0$ were measured at a beam momentum of 0.95 GeV/c ($T_p \approx$ 400 MeV) using the short version of the COSY-TOF spectrometer. The implementation of a central calorimeter provided particle identification, energy determination and neutron detection in addition to time-of-flight and angle measurements. Thus all pion production channels were recorded with 1-4 overconstraints. The total and differential cross sections obtained are compared to previous data and theoretical calculations. Main emphasis is put on the discussion of the $pp\pi^0$ channel, where we obtain angular distributions different from previous experimental results, however, partly in good agreement with recent phenomenological and theoretical predictions. In particular we observe very large anisotropies for the $\pi^0$ angular distributions in the kinematical region of small relative proton momenta revealing there a dominance of proton spinflip transitions associated with $\pi^0$ $s$- and $d$-partial waves and emphasizing the important role of $\pi^0$ d-waves.
Measured angular distribution for elastic P P scattering in the CM system normalised to the data in the SAID database (Arndt et al. PR C62,034005(2000). This measurement is made to determine the luminosity.
The analyzing power A N of proton-proton, proton-hydrocarbon, and antiproton-hydrocarbon, scattering in the Coulomb-nuclear interference region has been measured using thhe 185 GeV/ c Fermilab polarized-proton and -antiproton beams. The results are found to be consistent with theoretical predictions within statistical uncertainties.
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Polarization and differential cross-section data for elastic scattering of positive pions on protons between 0.82 and 2.74 GeV/ c are presented. A dip in the polarization, at constant u ≈ −0.65 GeV 2 , is observed. The data are compared with published phase-shift analyses.
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Polarization distributions and differential cross section data for elastic scattering of negative pions on protons between 865 and 2732 MeV/ c are presented. They are compared with published phase-shift analyses.
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A polarized proton beam extracted from SATURNE II was scattered on an unpolarized CH 2 target. The angular distribution of the beam analyzing power A oono was measured at large angles from 1.98 to 2.8 GeV and at 0.80 GeV nominal beam kinetic energy. The same observable was determined at the fixed mean laboratory angle of 13.9° in the same energy range. Both measurements are by-products of an experiment measuring the spin correlation parameter A oon .
Analysing power measurements at a fixed laboratory angle of 13.9 degrees.
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Both the np and the pp analyzing powers were measured simultaneously using the SATURNE II polarized deuteron beam at 0.550, 0.725, 0.900 and 1.15 GeV/nucleon. The results for the pp analyzing power coincide with the free pp elastic scattering data. We thus can assume that also the np analyzing power is equal to the one for scattering of free polarized neutrons. The np data cover the angular region 90° ≤ θ CM ≤ 125°. Our results for the np analyzing power clarify a discrepancy between earlier data at 0.5 GeV and allow conclusions about the energy dependence of the minimum of polarization at θ CM ⋍ 100° in the region from 0.5 to 0.9 GeV.
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Backward elastic scattering has been measured for π + p at 2.85 and 3.30 GeV/ c and for π − p at 3.30 GeV/ c . The π + p angular distributions show steep backward peaks, whereas the π − p distribution is flatter. At 2.85 GeV/ c the π + p differential cross section close to 180° is more than twice that at 3.30 GeV/ c , supporting the assignment J P = 11 2 + for Δ δ (2420) resonance. The π + p data at 2.85 GeV/ c indicate the onset of a dip at cos θ c.m. ≈ −0.97.
The data for cos(theta) = 1 is the extrapolation.
The data for cos(theta) = 1 and U = 0 are the extrapolations.
The data for cos(theta) = 1 and U = 0 are the extrapolations.
The spin correlation parameters A 00 kk and A 00 sk were measured at 0.874, 0.934, 1.095, 1.295, 1.596, 1.796, 2.096, and 2.396 GeV, using the SATURNE II polarized proton beam and tha Saclay frozen spin polarized target. The present results for beam-target spin correlations obtained during measurements of three-spin index observables confirm, in particular, relatively large positive values of A 00 sk at certain energies and angles, as was shown in previously published data from a dedicated experiment.
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Polarization and differential cross-section data for elastic scattering of negative kaons on polarized protons between 865 and 1330 MeV/ c are presented. Comparisons are made with predictions given by published energy dependent phase-shift analyses. The Legendre expansion coefficients characterizing the polarization distributions show remarkable structures resulting from excitation of Λ- and Σ-resonances. An analysis of the elastic and charge-exchange data in this region of momenta supports the assignments of J P = 3 2 + for the Λ(1870) resonance. The occurence of zero crossings in the polarization data is discussed.
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Polarization and differential cross-section data at 16 momenta between 0.86 and 2.74 GeV/ c are presented. (Preliminary data on some of the momenta have been published earlier.) In an energy-independent phase-shift analysis from threshold up to 2.5 GeV/ c , resonant-like as well as non-resonant solutions are found for the P 3 wave. An helicity flip-non-flip decomposition of the partial waves partly supports the indications found in the analyses of other reactions that the pomeron is built up mainly from s -channel helicity non-flip contributions.
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