Momentum spectra for forward Σ− production on beryllium by protons of momentum 25.8 and 29.4 GeVc are presented. Data for the two primary proton momenta are compared for scaling behavior in the invariant cross section. In addition, the observed single-particle momentum distributions are compared with single-particle spectra from other inclusive reactions initiated by protons.
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Inclusive photoproduction cross sections for pions, kaons and protons have been measured in the photon fragmentation region and are compared with recent electroproduction data at q 2 = 1.16 (GeV/ c ) 2 . If the cross sections are normalized to the total hadronic cross sections at q 2 = 0 and q 2 = 1.16 (GeV/ c ) 2 , respectively, we observe that more pions, about an equal number of protons, but fewer kaons are found in the photoproduction case for x ≥ 0.3.
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We have measured the mean charged multiplicity n¯CH as a function of transverse momentum p⊥ of the forward proton in the reaction p+p→p+MM for five intervals of missing mass (MM) using our Multiparticle Argo Spectrometer System. We observe an increase of n¯CH for p⊥>1 GeV/c.
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Photoproduction is studied at 2.8 and 4.7 GeV using a linearly polarized monoenergetic photon beam in a hydrogen bubble chamber. We discuss the experimental procedure, the determination of channel cross sections, and the analysis of the channel γp→pπ+π−. A model-independent analysis of the ρ0-decay angular distribution allows us to measure nine independent density-matrix elements. From these we find that the reaction γp→pρ0 proceeds almost completely through natural parity exchange for squared momentum transfers |t|<1 GeV2 and that the ρ production mechanism is consistent with s-channel c.m. helicity conservation for |t|<0.4 GeV2. A cross section for the production of π+π− pairs in the s-channel c.m. helicity-conserving p-wave state is determined. The ρ mass shape is studied as a function of momentum transfer and is found to be inconsistent with a t-independent Ross-Stodolsky factor. Using a t-dependent parametrization of the ρ0 mass shape we derive a phenomenological ρ0 cross section. We compare our phenomenological ρ0 cross section with other experiments and find good agreement for 0.05<|t|<1 GeV2. We discuss the discrepancies in the various determinations of the forward differential cross section. We study models for ρ0 photoproduction and find that the Söding model best describes the data. Using the Söding model we determine a ρ0 cross section. We determine cross sections and nine density-matrix elements for γp→Δ++π−. The parity asymmetry for Δ++ production is incompatible with simple one-pion exchange. We compare Δ++ production with models.
FROM QUOTED TOPOLOGICAL CROSS SECTIONS. 1.44 GEV CROSS SECTION PUBLISHED PREVIOUSLY.
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π − p → π 0 n and π − p → η n differential cross sections have been measured in nine nuclei ranging from hydrogen to lead at a 7.82 GeV/ c beam momentum and in a range of t going from 0 to −2 (GeV/ c ) 2 . The results can be understood in the framework of the Glauber theory which allows in addition a determination of the π 0 and η total cross sections on nucleons.
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Small angle elastic scattering events have been observed at the CERN Intersecting Storage Rings. Directions of both particles as well as the collision vertex are reconstructed with the help of four sets of spark chambers, two for each of the two arms. The elastic nature of the events is demonstrated by a collinearity requirement. We find values for the (diffraction) slope parameter in disagreement with the simple linear extrapolation of lower energy (Surpukov) data.
NUMBER OF EVENTS 87364.
NUMBER OF EVENTS 8305.
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The cross section for the production of Ξ + particles in K + p interactions at 12.7 GeV/ c is 10 ± 3 μ b; the Ξ − production cross section is 2.5 ± 1.0 μ b; the upper limit on Ω − or Ω + production is 0.4 μb. The Ξ − are produced preferentially in the backward direction in the CM system while the Ξ + are produced mainly forward. The mass and lifetime of the Ξ + agree with the accepted values for the Ξ − hyperon.
Cross sections have been corrected for the detection probability of all observed hyperons involved in these reactions.
Elastic and inelastic K L S regenerative scattering on copper and lead nuclei have been observed up to a momentum transfer of 0.17 GeV/ c . The elastic differential cross-section is of a ”diffractive” type. It can be described successfully in terms of an optical model only assuming an appreciable neutron excess in the vicinity of the nuclear surface.
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Measurements on the production of intermediate momenta negative pions, negative kaons, and antiprotons by protons of 43 GeV, 52 GeV and 70 GeV on aluminium nuclei are reported.
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