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
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Analyzing powers for πp elastic scattering were measured using the CHAOS spectrometer at energies spanning the Δ(1232) resonance. This work presents π+ data at the pion kinetic energies 117, 130, 139, 155, 169, 180, 193, 218, 241, and 267 MeV and π− data at 87, 117, 193, and 241 MeV, covering an angular range of 50°<~θc.m.<~180° at the higher energies and 90°<~θc.m.<~180° at the lower energies. Unique features of the spectrometer acceptance were employed to reduce systematic errors. Single-energy phase shift analyses indicate the resulting S11 and S31 phases favor the results of the SM95 phase shift analysis over that of the older KH80 analysis.
Measurement of the PI+ analysing power at 117 MeV.. The data were collected in the conventional mode and may be independently floated within the systematic error.
Measurement of the PI+ analysing power at 139 MeV.. The data were collected in the conventional mode and may be independently floated within the systematic error.
Measurement of the PI- analysing power at 87 MeV.. The data were collected in the conventional mode and may be independently floated within the systematic error.
The differential cross sections for π + p elastic scattering at0.6, 1.0, 1.5, 2.0, GeV/ c for π - p at 1.0, 1.5, 2.0 GeV/ c , for K - p at 1.2, 1.8, 2.6 GeV/ c and for K - p at 0.9, 1.2, 1.4, 1.6, 1.8, 2.6 GeV/ c have been measured with an overall accuracy ofthe order of 1 to 2% in an electronics experiment over the angular region corresponding to momentum transfer t between 0.0005 and 0.10 GeV 2 . Making use of the interference effects between the Coulomb and the nuclear interaction, we have determined the magnitude and sign of the real part of the scattering amplitude near t = 0. The K ± p real parts have been used in a dispersion relation to derive the value of the KNΛ coupling constant.
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Results are presented from experiment WA7 at the CERN SPS, which has measured the elastic differential cross sections of π ± p, K ± p, p p and pp at incident momen ta of 20, 30 and 50 GeV/ c . The measurements cover the momentum transfer range 0.5 < | t | < 8 (GeV/ c ) 2 , corresponding to c.m. scattering angles between 10° and 50°. The experimental set-up, trigger logic and data analysis are described. The experimental results are compared with existing meson-proton and nucleon-proton data at lower and higher energies covering the medium- and large-| t | region. Some prominent models and their predictions for elastic scattering at WA7 energies and beyond are reviewed, with emphasis on geometrical scaling, factorizing eikonal models, lowest-order QCD and other dynamical exchange-type models. Results for p p two-body annihilation into π − π + and K − K + at 30 and 50 GeV/ c , obtained in parallel with the elastic p p data, are also presented.
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We have measured charged-particle multiplicities and elastic and inelastic cross sections for π+p and pp interactions at 60 GeV/c. The data are from a 30 000-picture exposure of the 30-inch bubble chamber to a tagged but unseparated positive-particle beam at Fermilab. The low-order moments of the inelastic multiplicity distributions for all charged particles are 〈n〉 = 5.60±0.09, f2 = 0.96±0.31, and 〈n〉D = 2.19±0.06 for pp reactions and 〈n〉6.23±0.10, f2 = 1.63±0.37, and 〈n〉D = 2.22±0.06 for π+p collisions.
NORMALIZED TO A TOTAL CROSS SECTION OF 38.3 MB. CORRECTED FOR SMALL -T LOSSES AND FOR PI0 MESONS.
NORMALIZED TO A TOTAL CROSS SECTION OF 23.2 MB. CORRECTED FOR SMALL -T LOSSES AND FOR PI0 MESONS.
FORWARD CROSS SECTIONS ARE CONSISTENT WITH OPTICAL POINT FOR PURELY IMAGINARY ELASTIC AMPLITUDES.
We report the results of the investigation of 18 500 frames of π+p interactions in the Brookhaven 20-in. bubble chamber at an incident energy of 900 MeV. It is found that single-pion production proceeds almost entirely through formation of the N33* isobar. The production mechanism of the N33* is analyzed in terms of its spin density matrix. Comparison is made with Stodolsky and Sakurai's ρ-exchange model and with the absorptive peripheral model.
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Elastic cross-section measurements are presented for π ± −p at 20 GeV/ c and π − −p at 30 GeV/ c incident momenta in the large angle region (50° to 90° in the c.m. system). The data are compared with published lower energy elastic cross sections. A test is made of the dimensional counting rules for π ± −p elastic scattering and some indication of a deviation from this rule is observed in the π − −p case. A comparison is also made with the predictions of the constituent interchange model. Although the broad features of the predictions are confirmed, there are some important discrepancies. Finally, the predictions of the model due to Preparata and Soffer are also compared with the new data.
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THE UPPER LIMIT QUOTED WHEN NO EVENTS OBSERVED IS THE CROSS SECTION CORRESPONDING TO ONE DETECTED EVENT.
THE UPPER LIMIT QUOTED WHEN NO EVENTS OBSERVED IS THE CROSS SECTION CORRESPONDING TO ONE DETECTED EVENT.
The differential cross section for π ± p elastic scattering below 2 GeV/ c has been measured at small forward pion angles by an electronics experiment. The interference effects observed between the Coulomb and the nuclear interaction have been used to determine the magnitude and sign of the real parts of the π ± p forward scattering amplitude. The latter are compared to the values predicted by the dispersion relations.
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The differential cross section for π±−p elastic scattering at 180° was measured from 0.572 to 1.628 GeVc using a double-arm scintillation-counter spectrometer with an angular acceptance θ* in the center-of-mass system defined by −1.00≤cosθ*≤−0.9992. The π+−p cross section exhibits a large dip at 0.737 GeVc and a broad peak centered near 1.31 GeVc. The π−−p cross section exhibits peaks at 0.69, 0.97, and 1.43 GeVc.
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A simple, large-solid-angle apparatus, specially suited for the measurement of backward elastic scattering of medium-energy pions on protons and deuterons, is described. The method of analysis which reduces background and determines elastic events from a data sample of 185 MeV negative pions incident on a D 2 O target is discussed. Results for 141 MeV π + p and 185 MeV π − p backward cross-sections are also presented and compared with cross-sections calculated from known phase shifts.
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