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《Physics letters. [Part B]》1988,200(3):266-271
Distributions of the leading positive particle have been measured in collisions of a 200 GeV/c proton beam with hydrogen, Mg, Ag and Au targets using the FNAL Hybrid Spectrometer. Estimates of the rapidity loss of the projectile have been obtained as a function of the target mass, the multiplicity of negative particles and the number of recoil protons. We obtained a lower limit of the rapidity loss of 2.0±0.2 for central p+Au collisions. The impact parameter dependence of the momenta of the first few leading particles has also been investigated with important implications to estimates of energy densities obtained in central collisions.  相似文献   

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Two- and three-particle rapidity correlations are analyzed inK + p and π+ p-interactions at 250 GeV/c. The main contribution to the two- and three-particle correlation functions comes from mixing of events of different multiplicity. The (short range) two-particle correlation remaining after exclusion of mixing is significantly larger for (+?) than for the equal charge combinations, and is positive for a wider range in rapidity difference. FRITIOF and a 2-string DPM are excluded by our data. A quark-gluon (multi-)string model can describe our inclusive correlation function, but needs to be tuned on the short range part. The multiplicity mixing part increases much faster with increasing energy than the short range part. In the central region, our correlation is similar to that observed ine + e ? and μp collisions at similar energy.  相似文献   

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The NA22 data onπ ? π ? correlations are analyzed in terms of a number of two- and three-dimensional parametrizations (Gaussian space-time, Goldhaber, Bowler string-like, Bertsch hydrodynamical, Kopylov-Podgoretskii, etc.). Contrary to the results obtained for e+e? andµp collisions, the Goldhaber parametrization, as well as string-like models, fail in describing the hadron-hadron data. Better fits are obtained in the framework of surface-emitting fireball-like models, both when including and excluding hydrodynamical expansion of nuclear matter. Our results indicate that pion radiation occurs at earlier stages of matter evolution than in nuclear collisions.  相似文献   

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We present data on the flow of energy and charge in π+ p,K + p andpp interactions at 250 GeV/c. The energy and charge flow in the beam c.m. hemisphere is analysed in terms of the cluster-invariant Bialas-Ochs-Stodolsky variable λ=cot θ/E jet. The profile functionsdQ/dλ anddE/dλ indicate a widening inp T of jets between 32 and 250 GeV/c incident laboratory momentum, whereas the ratiodQ/dE is energy independent. The data are compared to μp deep-inelastic scattering resutls and to expectations from the single string LUND model, the Dual Parton Model and the two-string LUND model (FRITIOF).  相似文献   

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Final data on topological cross sections are presented. Inclusive single particle distributions for the reactionsK + p→ π± X at 32 GeV/c are discussed and compared with data at lower energies. Early scaling in the fragmentation regions is confirmed, while cross sections in th central region continue to rise with energy even faster than inpp interactions. Thex-andp T -dependence of the π+? ratio inK + p interactions is discussed and a comparison of reactionsK + p→ π± X andK ? p→ π± X at 32 GeV/c is made in the context of constituent models. We also present transverse momentum distributions, show prominent seagull effects and study how they are influenced by resonance production.  相似文献   

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Cross-sections are obtained for coherent interactions of π+ and K+-mesons with Al and Au nuclei at 250 GeV/c, leading to three, five and seven charged mesons. The total coherent cross-section is (4.3 ± 0.5)% of the inelastic cross-section for each of the four meson-nucleus interactions. In 85% of the coherent events, the charged meson production is accompanied by neutral mesons. Effective mass distributions are presented for coherently produced particles, including charged mesons and photons, carrying total measured energy of more than 85% of the initial energy. Charged particle and γ spectra are analysed. No charge asymmetry is observed within the coherently produced cluster.  相似文献   

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The missing mass spectrum opposite the proton in a 750 000 picture exposure, 13 GeV/cπ+p bubble chamber experiment, is investigated in two and four pion channels for structures observed or denied by boson spectrometers at the same energy in the reaction π?p→X?p.In the four pion final state the R+ enhancement is observed clearly and the possibility of multi-component mass structure is considered. Treating the phenomenon as one object, cross sections and branching ratios are derived for intermediate quasi two and three body decay modes (ωπ, ??, A2π, ?ππ). The signals in the two pion state and for the neutral state produced opposite Δ++(1231) are also presented and an elasticity is calculated.  相似文献   

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Data are presented on the production of the KNπ final states in K+p interactions at 7.3 GeV/c. The energy dependence of the KNπ final state cross sections, the effective-mass distributions, and the spectra of c.m. longitudinal momenta are given, and features of these data are compared with predictions of the generalized Veneziano (GV) model. Furthermore, we present the momentum transfer and decay angular distributions for K1 (890), K1 (1420) and Δ (1236) production within the KNπ final states and discuss these quasi-two-body reactions in terms of the GV model.  相似文献   

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