The 2m hydrogen bubble chamber was exposed to a separated beam of α-particles from the ITEP synchrotron. The momentum of the 4 He-nuclei beam averaged over the bubble-chamber fiducial volume was equal to 2.7 GeV/ c (the kinetic energy of the initial protons in the nuclear rest frame was T p = 220 MeV). The total and topological cross sections were measured as well as the cross section of separate 4 He-p interaction channels and the differential cross sections d σ d t of the elastic 4 He-p scattering. The experimental results have been compared with the data of the previous experiments and with the theoretical predictions based on the Glauber-Sitenko multiple-scattering theory.
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The mechanism of the reaction 3 He + p → p + p + d is studied by making use of the ITEP 80 cm liquid-hydrogen bubble chamber exposed to a beam of 5 GeV/ c 3 He nuclei. The reaction cross section is equal to 20.6 ± 0.3 mb. The phase-space regions associated with quasifree scattering (QFS) and final-state interactions (FSI) are selected. Angular, mass and momentum distributions of the reaction products are obtained in the entire kinematically allowed range. The experimental data in the QFS region are compared with theoretical calculations based on the simplest pole-diagram approximation. The 3 He and deuteron wave functions (WF) correspond to the realistic RSC potential. The D-wave components of these WF are taken into account. The absolute value of the cross section and shape of the distributions are described as a whole reasonably well within the frame of the model considered in the kinematical region where FSI may be neglected. But at large spectator momenta there is an essential disagreement. The possible reasons for this are discussed.
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The total and topological 4Hep cross sections as well as the cross sections of the separate 4Hep interaction channels and the differential cross sections of the elastic 4Hep scattering were measured using the 2m hydrogen bubble chamber exposed to a separated beam of alpha-particles from the ITEP synchrotron at 5 GeV/c (the kinetic energy of the initial protons in the nuclear rest frame was 620 MeV). The data obtained have been compared with the results of the previous experiments and with the theoretical predictions based on the Glauber-Sitenko multiple-scattering theory.
Only statistical errors are presented.
Only statistical errors are presented.
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We have measured the total and subchannel cross sections for the reaction p¯p→p¯pπ+π− at 49 GeV/c. This reaction is dominated by two production mechanisms, diffraction and meson exchange. In addition, we have measured the total cross section for p¯p→p¯p2π+2π− and compared it to values at other momenta and with the corresponding pp interaction. Within the present statistics, no significant amount of exclusive annihilation is found into two, four, and six charged pions.
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We report a measurement of the diffraction dissociation differential cross section d2σSD/dM2dt for p¯p→p¯X at √s =546 and 1800 GeV, M2/s<0.2 and 0≤-t≤0.4 GeV2. Our results are compared to theoretical predictions and to extrapolations from experimental results at lower energies.
Single diffraction dissociation cross section.
We present results from a measurement of double diffraction dissociation in $\bar pp$ collisions at the Fermilab Tevatron collider. The production cross section for events with a central pseudorapidity gap of width $\Delta\eta^0>3$ (overlapping $\eta=0$) is found to be $4.43\pm 0.02{(stat)}{\pm 1.18}{(syst) mb}$ [$3.42\pm 0.01{(stat)}{\pm 1.09}{(syst) mb}$] at $\sqrt{s}=1800$ [630] GeV. Our results are compared with previous measurements and with predictions based on Regge theory and factorization.
Cross sections for double diffractive production.
We report the first observation of diffractively produced W bosons. In a sample of W -> e nu events produced in p-barp collisions at sqrt{s}=1.8 TeV, we find an excess of events with a forward rapidity gap, which is attributed to diffraction. The probability that this excess is consistent with non-diffractive production is 1.1 10^{-4} (3.8 sigma). The relatively low fraction of W+Jet events observed within this excess implies that mainly quarks from the pomeron, which mediates diffraction, participate in W production. The diffractive to non-diffractive W production ratio is found to be R_W=(1.15 +/- 0.55)%.
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