We present a study of leading protons and antiprotons inp-nucleus and\(\bar p\)-nucleus on Be, Cu, Ag, W, and U targets. The experiment was performed at the CERN-SPS at a beam energy of 120 GeV. For all targets a suppression of secondary antiprotons with respect to protons is observed. The difference between the\(\bar p\) andp spectra increases with decreasing χ-values and the effect is stronger for heavier nuclei. The features of the data are qualitatively consistent with multiple-collisions modesls. The data are analysed in terms of a dual parton model which gives a satisfactory description of leadingp and\(\bar p\) spectra.
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The ρ0-meson spin alignment is studied in p¯p interactions at 22.4 and 12 GeV/c and in the reaction p¯p→2π++2π−+neutrals at 5.7 GeV/c. An essential ρ0-meson spin alignment is observed. The values of the ρ00T element of the ρ0-meson spin-density matrix in the transversity frame are 0.56 ± 0.07, 0.53 ± 0.05, and 0.54 ± 0.04 for the above-mentioned interactions, respectively. An increase of ρ00T with ρ0 transverse momentum is obtained.
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DATA WERE EXTRACTED FROM ADEUT-BREAKUP EVENTS,SEE R=PR D10, 3573 FOR EXAMPLE.
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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Light ion collisions with carbon target at 4.2 GeV/c/N are studied. Pion multiplicity distributions, momentum and angular spectra are analysed. These data are described in terms of models assuming independent interactions of nucleons from the projectile nucleus with the target.
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We present the first results on the production of fast (p>10 GeV/c)p,\(\bar p\), Λ and\(\bar \Lambda \) from π± hydrogen and nucleus interactions at 30 GeV/c using the CERN Ω′ spectrometer. We have used five nuclear targets (C, Al, Cu, Sn, Pb) to study theA-dependence of the inclusive particle distributions in the region 0.3<xF<0.6. The high statistical level of our experiment allows us to demonstrate the differentA-behaviour of baryon and antibaryon inclusive reactions. We relate this difference to the final state interaction inside a nucleus using the formation-zone model.
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The reactions\(K^ -Be \to {}^(\bar K^) *^0 (890)X,\pi ^ -Be \to {}^(\bar K^) *^0 (890)X\), have been studied in a 175 GeV unseparated hadron beam in the kinematic range 0<xF<1.0 andpT2<5 GeV2. Integrated cross-sections and the dependence of the cross-sections on the longitudinal and transverse momentum are presented, together with quark counting rules predictions. The nuclear dependence ofK− fragmentation intoK*0(890) with respect to Feynmanx is investigated from hydrogen to beryllium.
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