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.
Differential cross-sections for proton-proton elastic scattering have been measured covering the angular range from 50° to 90° c.m. at twelve incident momenta from 1.3 to 3.0 GeV/c. The angular distributions are quite smooth, but there is evidence of structure in the energy dependence of fixed-angle cross-sections at |t| ∼ 1 (GeV)2.
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Measurements of wide angle elastic p-p scattering between 7 and 12 GeV/c are reported. Structure found in the angular distributions is suggestive of diffraction.
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Differential cross sections for the elastic scattering of K + mesons on protons have been measured at 12 lab momenta between 130 and 755 MeV/ c using a hydrogen filled bubble chamber. The results are consistent with a repulsive S-wave nuclear force. A phase-shift analysis yielded the following values of the low-energy parameters: a S 1 2 =(0.309±0.002) fm , r S 1 2 =(0.032±0.02) fm a P 1 2 =(0.021±0.002) fm , a P 3 2 =(0.013±0.001) fm 3
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We have measured the differential cross section for small angle p−p scattering from 25 to 200 GeV incident energy and in the momentum transfer range 0.015<|t|<0.080 (GeVc)2. We find that the slope of the forward diffraction peak, b(s), increases with energy and can be fitted by the form b(s)=b0+2α′ lns, where b0=8.3±1.3 and α′=0.28±0.13 (GeVc)−2. Such dependence is compatible with the data existing both at higher and lower energies. We have also obtained the energy dependence of the p−p total cross section in the energy range from 48 to 196 GeV. Within our errors which are ± 1.1 mb the total cross section remains constant.
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Proton-proton and proton-deuteron elastic scattering has been measured for incident laboratory energy from 50 to 400 GeV; minimum |t| values were, for p−p, 0.0005 (GeV/c)2, and for p−d, 0.0008 (GeV/c)2. From the differential cross sections we have determined the ratios of the real to imaginary parts of the forward scattering amplitude, ρpp and ρpd, for p−p and p−d scattering. Using a Glauber approach and a sum-of-exponentials form factor we obtain ρpn for p−n scattering.
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NORMALIZATION UNCERTAINTY IS 0.90 PCT.
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Interactions of 2.08−BeVc positive pions with protons have been studied using the 20-in. hydrogen bubble chamber and the alternating gradient synchrotron at Brookhaven National Laboratory. Using 3000 elastic and 8000 inelastic events, the partial cross sections for elastic scattering and for meson production have been measured. The ρ+, ρ0, ω0, and η0 resonances are produced strongly and emerge predominantly in the forward direction in the center-of-mass system, suggesting a peripheral mechanism for their production. The possibility of explaining these reactions by specific particle-exchange models is investigated. More than 75% of the ρ0, ω0, and η0 are produced with the N33* (1238) isobar. The N* (1688) is produced in about one-third of the π+π+N final states. Cross sections for production of ρ+p, π+pω, N33*ω, π+pη, N33*η, π+pρ0, N33*ρ0, N15*π+, and N33*π0, are given. A1, B, φ, and X mesons are not observed.
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