Ilford G-5 emulsions were exposed to an external, 3.5 GeY proton beam of the Berkeley Bevatron. A total of 1200 nuclear interactions of beam protons was located, of which 128 were identified as protonproton collisions. Multiple scattering, blob density, range and angle measurements were employed to determine the cross-sections for elastic and inelastic interactions as well as the identities and center-of-mass system momenta and scattering angles of secondaries from inelastic proton-proton interactions. This analysis indicates a cross-section of (8.0±2.4) mb for elastic events, (24.1±2.9) mb for two-prong inelasitc events, (7.9±1.4)mb for four-prong events and (0.6±0.3) mb for sixprong events. The mean charged pion multiplicity in inelastic interactions is 1.5±0.2 and corresponds to an average degree of inelasticity of 0.45 ±0.06. Center-of-mass system angular distributions of charged secondaries from inelastic events display a peaking for small scattering angles which is most pronounced for protons and pions from events with low secondary multiplicity. Momentum and transverse momentum distributions of secondary protons and pions from inelastic events are presented and compared with the results at other energies. The angular distribution of elastically scattered protons is found to be in fair agreement with that predicted by a uniform optical model of radius 1.25-10-13 cm and opacity 0.66.
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Elastic and inelastic 19.8 GeV/c proton-proton collisions in nuclear emulsion are examined using an external proton beam of the CERN Proton Synchrotron. Multiple scattering, blob density, range and angle measurements give the momentum spectra and angular distributions of secondary protons and pions. The partial cross-sections corresponding to inelastic interactions having two, four, six, eight, ten and twelve charged secondaries are found to be, respectively, (16.3±8.4) mb, (11.5 ± 6.0) mb, (4.3 ± 2.5) mb, (1.9 ± 1.3) mb, (0.5 ± 0.5) mb and (0.5±0.5)mb. The elastic cross-section is estimated to be (4.3±2.5) mb. The mean charged meson multiplicity for inelastic events is 3.7±0.5 and the average degree of inelasticity is 0.35±0.09. Strong forward and backward peaking is observed in the center-of-mass system for both secondary charged pions and protons. Distributions of energy, momentum and transverse momentum for identified charged secondaries are presented and compared with the results of work at other energies and with the results of a statistical theory of proton-proton collisions.
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Results are presented on π±p, K±p, and p±p elastic scattering measured with an apparatus having acceptance of 0.5<−t<2.5 (GeV/c)2 and 0.9<−t<11 (GeV/c)2 at 100 and 200 GeV/c, respectively. A diffractionlike dip is seen for the first time in the π−p t distribution at −t=4 (GeV/c)2. All meson-proton cross sections are found to be similar in the range 1<−t<2.5 (GeV/c)2, although some small systematic differences are observed. Cross sections for pp and p―p are compared with previous data.
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Hard hadronic scattering was studied by selecting 150 GeV and 300 GeV π − p and pp events with large energy in a 240 cell calorimeter covering 45† to 135† in the c.m.s. polar angle and the full 2 π azimuth. A downstream calorimeter measured the remaining energy flow at smaller angles. For large energy deposited in the segmented calorimeter the proton induced cross section drops below the pion induced cross section, as expected in a constituent scattering picture. However, neither a simple energy scaling of the cross section nor a dominant jet structure of the events is observed. No evidence was found for recently proposed higher-twist mechanisms leading to events
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Data are presented on elastic πp and Kp scattering for values of −t up to 2.5 and 3.5 (GeV/c)2 at incident momenta of 100 and 200 GeV/c, respectively. All of the cross sections are found to be nearly identical, although there is some momentum dependence of the π+p data; a small systematic difference observed between pion and kaon data cannot be explained by geometrical scaling.
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Backward elastic scattering of π± on protons has been measured for incident pion momenta between 30 and 90 GeV/c and 0≤−u≤0.5 (GeV/c)2. The u dependence of the cross sections is similar to that observed at lower momenta, and Regge models give acceptable fits to the data.
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Antiproton-proton elastic scattering has been measured at 100 GeV/c for 0.5<−t<2.5 (GeV/c)2 and at 200 GeV/c for 0.9<−t<4 (GeV/c)2. The data show that the −t≃1.4 (GeV/c)2 dip recently observed at 50 GeV/c persists to higher incident momenta. Proton-proton measurements made at the same beam momenta show similar structure.
CLEAR DIP OBSERVED AT -T=1.4 (GEV/C)**2.
Interactions of 200-GeV/c protons and antiprotons on hydrogen, argon, and xenon targets were studied with a streamer-chamber vertex spectrometer at the CERN SPS. Results on multiplicities, rapidity distributions, and correlations are presented and compared with predictions of current models.
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'PRODUCED PARTICLES' (SEE CONDITIONS).
Large transverse energy cross sections of 300 GeV/ c pions and protons on hydrogen have been measured with a segmented calorimeter covering the central rapidity region −0.88 < y < 0.67 and 2 π in azimuth. The selected events show large multiplicities and no jet-like event structure. Processes more complicated than the scattering of two constituents appear to dominate these inelastic collisions.
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Results are presented on the measurement of 200-GeV/c π−p elastic scattering at −t from 0.8 to 11 (GeV/c)2. As −t is increased, dσdt falls by ∼6 decades to a prominent dip at 4 (GeV/c)2, followed by a second maximum and than a slow decrease with increasing −t.
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