Results are presented on the elastic scattering of photons by protons. The incident photon energy ranged from 0.55 GeV to 4.5 GeV, and the four-momentum transfer t ranged from 0.12 to 1.0 (GeV/c)2. The data at large angles, 60°<θ*<115°, are characterized by a pronounced excitation of the D13(1518) resonance, a shoulder in the 1688-MeV mass region, and a precipitous drop thereafter in the cross section as a function of incident energy. The low-t data are characterized by a diffraction slope of 5 (GeV/c)−2. The data are inconsistent with the predictions of the vector-dominance model if the latter is restricted to ρ0, ω, and φ vector mesons.
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We present differential cross-section data for the reaction π+p→π+p near 180° in the center-of-mass system at beam momenta between 3.25 GeVc and 10 GeVc.
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We have observed a second sharp peak in the cross section for e+e−→hadrons at a center-of-mass energy of 3.695±0.004 GeV. The upper limit of the full width at half-maximum is 2.7 MeV.
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Full angular distributions of the polarization parameter in elastic K+p scattering at 1.37, 1.45, 1.60, 1.71, 1.80, 1.89, 2.11, and 2.31 GeV/c are presented. These data were obtained in an experiment at the Zero Gradient Synchrotron using a polarized proton target with arrays of scintillation and Čerenkov counters to detect the scattered particles.
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TWO EVENTS SEEN WITH MASSES 800 +- 90 MEV AND 1400 +- 90 MEV. THE FIRST WHEN INTERPRETED AS ETAPRIME PRODUCTION GIVES A WIDTH OF 11, +15, -8 KEV FOR ETAPRIME --> 2GAMMA USING THE EQUIVALENT PHOTON APPROXIMATION.
An experiment has been performed to study the inclusive photoproduction of π 0 mesons. Photoproduced π 0 's were detected in a hodoscope consisting of 14 lead glass Cerenkov counters. To obtain the cross sections at a photon energy of 6 GeV we used the photon-difference method. Data are presented in terms of the Feynman variable x = q ‖ ∗ (√s/2) and the trnasverse momentum q⊥. We have measured four q ⊥ distributions at x = 0.2, 0.4, 0.6 and 0.8. The results dhow that the π 0 rate at small values of q ⊥ is smaller than the π± rate. The data can be fitted smoothly by a form A exp (− Bq ⊥ 2 ) with a value about 3.5 GeV −2 for the slope parameter B .
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At the Bonn 2.5 GeV synchrotron the differential photoproduction cross section d σ /d t of φ mesons has been measured at a photon energy of 2.0 GeV at fibe different t values between 0.23 < | t | < 0.73 (GeV/ c ) 2 . The φ meson was detected by magnetic momentum analysis of both charged decay K mesons and by a time of flight and angle measurement of the coincident recoil proton. We found an exponential behaviour for the t dependence of the cross section. The measured slope of the exponential decrease was b = (4.01 ± 0.23) (GeV/ c −2 . This result, combined with previous measurements at higher energies, implies that the slope of the pomeron trajectory is compatible with zero. In addition the experiment yielded a value of the φ mass, m φ = (1019.4 ± 0.8) MeV and a value of the φ width, Γ = (4.4 ± 0.4) MeV.
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The results of the total cross section measurements of neutrons on protons, deuterons and nuclei C, O, Al, Cu, Sn, Pb in the energy range of 28–54 GeV are reported.
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In an experiment with the CERN 2 metre DBC the reaction K$^+$d $\to$ K$^0 \pi^+$d is studied at an incident momentum of 4.6 GeV/c. The cross section is found to be (66 ± 10) μb for four-momentum transfer squared from target to recoil deuteron greater than 0.02 GeV 2 , and the reaction is dominated by the production of K$^*+$ (892) via natural parity exchange. Using data for the reactions K$^\pm$d $\to$ K$^{*\pm}$(892)d in the incident momentum range 2–13 GeV/ c the parameters of the effective exchanged trajectory are estimated.
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