The π0 inclusive cross section for c.m. production angles θ=90° and 22°>~θ>~5° at c.m. energies of s=23 and 53 GeV has been measured. This cross section is strongly dependent on both θ and s at small angles. The hypothesis of radial scaling is shown to be incapable of incorporating both θ and s dependence of the cross section. A recent quantum-chromodynamics calculation is in qualitative agreement with our results.
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We present here the results of an experiment to study the polarization in p−p elastic scattering at the incident momenta 5.15, 7.00, and 12.33 Ge V/c, at t values ranging between - 0.5 and - 6.5 (GeV/c)2. At each momentum we observe a relative maximum in the polarization around t=−1.8 (GeV/c)2. At 12.33 GeV/c the data exhibit a double zero near t=−2.4 (GeV/c)2 and another relative maximum near t=−2.9 (GeV/c)2. The results are discussed in terms of the Chu-Hendry optical model.
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We present herein the initial results of a large-angle elastic p−p polarization experiment which is now in progress at the Argonne ZGS (Zero-Gradient Synchrotron) accelerator. Data for the incident proton momentum of 5.15 GeVc are presented for 30∘≲θc.m.≲90∘. These results, which extend to t≈−4.0(GeVc)2, represent the first high-statistics p−p polarization measurements for |t| values greater than ∼2.5 (GeVc)2. We observe a minimum in the polarization near t=−0.8(GeVc)2, a smooth increase in the polarization until a maximum is attained near t=−1.8(GeVc)2, and then a monotonic decline in the polarization until the value of zero is reached at θc.m.=90∘. The data are analyzed in terms of an optical model.
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Results are presented from an experiment designed to make the first systematic study of the depolarization parameter in elastic proton-proton scattering at high energies. Measurements were made at 3.0 and 6.0 GeV/c at |t| values extending to 1.7 (GeV/c)2 at the higher momentum. A high-intensity unpolarized proton beam was incident on a polarized proton target and the polarization of the elastically scattered recoil protons was determined with a carbon analyzer. The results are discussed in the framework of optical and exchange models.
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The measurement of the proton-proton total cross section performed by the CERN-Pisa-Rome-Stony Brook Collaboration at the CERN ISR is discussed in detail. The total interaction rate, the elastic scattering rate in the forward direction, and the machine luminosity were measured simultaneously to obtain three different determinations of the total cross section. Consistent results were found, which made it possible to prove the reliability of the Van der Meer luminosity calibration within +-0.9% and to achieve a precision of +-0.6% in the measurement of the total cross section.
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Inclusive e+e− production in 17-GeV/c π−p collisions has been measured. An excess of e+e− pairs over those from known sources for 0.1<~mee<~0.6 GeV and x<0.5 was found. No evidence is found for enhancements in specific final states involving electrons and photons or charged particles. The photon multiplicity associated with these pairs is measured.
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Measurements of the proton-proton total cross section have been made with increased precision (±0.6%) over the ISR energy range s =23.5−62.7 GeV . Two different experimental methods gave consistent results, showing that the total cross section increases 10% over the ISR range and in addition that the absolute value of the ISR luminosity can be measured to ±0.9%.
CROSS SECTIONS ARE A WEIGHTED AVERAGE OF THOSE OBTAINED BY THE PISA-STONY BROOK METHOD AND BY THE CERN-ROME (OPTICAL THEOREM) METHOD.
Analyzing powers ( A y ) and spin-rotation-depolarization parameters ( D SS , D SL , D LS , D LL , D NN ) were determined for 500 MeV p + 2 H and p + 12 C inclusive quasielastic scattering at 10°, 15°, and 20° laboratory scattering angles. The p + 2 H data are consistent with the isospin-average of the proton-proton and proton-neutron scattering observables; the p + 12 C data are not. A relativistic plane wave impulse approximation calculation leads to better agreement with the p + 12 C spin-observables.
Inclusive quasielastic p deut measurements.
Inclusive quasielastic p c measurements.
The spin correlation parameter A00NN for 497.5 MeV proton + proton elastic scattering was determined over the center-of-momentum scattering angle region 23.1°–64.9 °. The new A00NN extend to more forward angles than existing A00NN and have significantly smaller statistical errors (±0.01–0.04). The A00NN are qualitatively described by recent phase shift analyses, but a quantitative shape and normalization discrepancy remains in the forward angle region. These new data provide important constraints for nucleon-nucleon spin-dependent amplitudes at forward angles which are used in theoretical models of nucleon-nucleus scattering.
Errors include statistical and systematic uncertainties.
Backward scattering in the reaction KL0p→pKS0 is studied in the momentum interval 1.0 to 7.5 GeV/c. Comparison of KL0p→pKS0 and K+p→pK+ backward scattering, where respectively Σ exchange and Λ plus Σ exchange can contribute in the u channel, reveals that dσdΩ180°(KL0p→pKS0dσdΩ180°(K+p→pK+) above the resonance region. This result provides direct evidence for the dominance of the Λ contribution over the Σ contribution in the K+p→pK+ production amplitude.
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