The reaction e − + p → e − + p + π 0 has been studied in the region of the Δ (1236) resonance at a four-momentum transfer of the virtual photon of 0.3 (GeV/ c ) 2 . Angles and momenta of the secondary electron and of the outgoing proton were measured in coincidence to obtain the angular dependence of the differential cross section. The angular distribution for s- and p-waves of the pion in the πN cm-system was fitted to the cross section for three W -bins around the maximum of the resonance. The contribution of the resonant multipoles M 1+ , E 1+ and S 1+ to the cross section as well as the contribution of the background amplitudes M 1− , E 0+ and S 0+ are given.
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Differential cross sections for π − p → η 0 n, η 0 → 2 γ have been measured from 20 to 50 GeV for four-momentum transfers − ≲ 3 (GeV/ c ) 2 . The cross sections decrease as a power of momentum and the forward scattering cone shrinks slowly. The parameters of the A 2 trajectory, which is considerably non-linear, have been determined.
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Differential cross sections for the process γ p → p η have been measuredd at c.m. angles of 28°, 35° and 42° at incident energies between 2 GeV and 2.8 GeV. Data from an earlier experiment below 2 GeV have been re-analysed and corrected. The whole set of data is compared with the form ( s − M 2 ) 2 d σ /d t , which fits data at higher energies. There is good agreement above 2 GeV, particularly at the largest angle, but strong departures below.
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THESE DATA ARE A REANALYSIS OF THOSE REPORTED IN P. S. L. BOOTH ET AL., NP B25, 510 (1971). THE CORRECTED RESULTS ARE IN GENERAL ABOUT TWICE THE OLD VALUES.
Photoproduction of π + and π − on deuterium has been measured in the photon energy range from 240 to 400 MeV and for pion c.m. angles between 15° and 180°. The pions were analysed in angle and momentum by a magnetic spectrometer. From the measured π − / π + ratio, corrected for Coulomb interactions in the final state, differential cross sections of the reaction γ +n→ π − +p were calculated. Together with the π + photoproduction our data show no isotensor contribution. Comparison of our data with the recent experiments done on the inverse reaction shows no evidence of a violation of time reversal invariance. With the measured π + photoproduction on deuterium, a test of the spectator model has been made. Using the closure-approximation of Chew and Lewis our data agree within a range of ±10%.
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The reaction p ̄ p → n ̄ n has been studied at an incident antiproton laboratory momentum of 1.13 GeV/ c . The antineutron was identified through a subsequent annihilation on a proton. In all, 2601 identified events were obtained. Total and differential cross sections are presented. Comparison is made with the predictions of the Bryan and Phillips model which, in this energy range, is succesful in describing the related reaction p ̄ p → p ̄ p . Here, the agreement is less good.
No description provided.
The reaction γ d→d ππ , γ p→p ππ and γ n→n ππ were studied in the SLAC 82″ deuterium filled bubble chamber, exposed to a linearly polarized photon beam of 7.5 GeV. All three reactions are dominated by ϱ 0 production. The differential cross section has a slope of ∼6.5 GeV −2 for nucleon reactions and a slope of ∼27 GeV −2 for coherent deuteron reactions. The behaviour of the density matrix elements shows that ϱ production conserves s -channel c.m.s. helicity and is dominated by natural parity exchange.
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The reactions p p → Λ Λ, Λ Σ 0 or Σ 0 Λ, Σ + Σ + are studied at an incident momentum of 3.6 GeV/ c in a 35.4 event/μb experiment performed in the CERN 2m HBC. Total and differential cross sections are presented. The polarization of the hyperons is measured as a function of t and for the reaction p p → Λ Λ the complete spin correlation matrix is given.
35.4 event/mub data sample used.
35.4 event/mub data sample used.
35.4 event/mub data sample used.
Total and partial γd, γp and γn reactions were studied in the SLAC 82 inch deuterium-filled bubble chamber, which was exposed to a linearly polarized photon beam at an energy of 7.5 GeV. We report total, topological and channel cross sections for these reactions. The γn average charge multiplicity was found to be one unit of charge less than the γp average charge multiplicity. The isoscolar-isovector interference term as calculated by comparing the γp charge symmetric reactions is found to be small.
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CHARGE MULTIPLICITY TOPOLOGICAL CROSS SECTIONS.
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The K − p reactions with final states Λπ 0 , Σ 0 π 0 , Λπ 0 π 0 , Λη and Σ 0 η have been studied at 14 momenta between 685 and 934 MeV/ c using optical spark chambers. The charged decay products of the Λ are detected by low mass spark chambers while γ-rays from π 0 and Σ 0 decays are detected in high mass chambers. Approximately 250 000 photographs were analysed from which partial and differential cross sections were determined. These results are presented with an energy dependent, single channel partial-wave analysis.
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A study has been made of the individual channels that contribute to the reaction K − p → Λ 0 + neutrals in the K − momentum range from 525 to 820 MeV/ c . Total cross sections are presented for the K − p → Λ 0 η 0 , Σ 0 Σ 0 π 0 , Λ 0 π 0 , Σ 0 π 0 and Σ 0 π 0 π 0 channels and differential cross sections for K − p → Λ 0 π 0 . The data were obtained in a heavy liquid bubble chamber experiment with an average gamma detection efficiency of 70%. Only events with all decay gammas detected were used for analysis. This is the first of a series of papers on this subject and presents the experimental technique in detail.
No description provided.
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