Photoproduction is studied at 2.8 and 4.7 GeV using a linearly polarized monoenergetic photon beam in a hydrogen bubble chamber. We discuss the experimental procedure, the determination of channel cross sections, and the analysis of the channel γp→pπ+π−. A model-independent analysis of the ρ0-decay angular distribution allows us to measure nine independent density-matrix elements. From these we find that the reaction γp→pρ0 proceeds almost completely through natural parity exchange for squared momentum transfers |t|<1 GeV2 and that the ρ production mechanism is consistent with s-channel c.m. helicity conservation for |t|<0.4 GeV2. A cross section for the production of π+π− pairs in the s-channel c.m. helicity-conserving p-wave state is determined. The ρ mass shape is studied as a function of momentum transfer and is found to be inconsistent with a t-independent Ross-Stodolsky factor. Using a t-dependent parametrization of the ρ0 mass shape we derive a phenomenological ρ0 cross section. We compare our phenomenological ρ0 cross section with other experiments and find good agreement for 0.05<|t|<1 GeV2. We discuss the discrepancies in the various determinations of the forward differential cross section. We study models for ρ0 photoproduction and find that the Söding model best describes the data. Using the Söding model we determine a ρ0 cross section. We determine cross sections and nine density-matrix elements for γp→Δ++π−. The parity asymmetry for Δ++ production is incompatible with simple one-pion exchange. We compare Δ++ production with models.
FROM QUOTED TOPOLOGICAL CROSS SECTIONS. 1.44 GEV CROSS SECTION PUBLISHED PREVIOUSLY.
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NO TMIN CORRECTION HAS BEEN MADE.
We present differential cross sections andΔ++ spin density matrix elements for the photoproduction processγp→π−Δ++ and differential cross sections for the processγp→π+Δ0. The incident photon energy dependence is studied and a comparison is made with previous experiments and with the predictions of a theoretical model.
DIFFERENTIAL CROSS SECTION AVERAGED OVER WHOLE ENERGY RANGE.
DIFFERENTIAL CROSS SECTION AVERAGED OVER WHOLE ENERGY RANGE.
DIFFERENTIAL CROSS SECTION FOR DIFFERENT ENERGY RANGES.
The differential elastic scattering cross sections for negative pions on ; protons were measured at incident momenta of 1.51, 2.01, and 2.53 Bev/c with ; emphasis on the angular region outside the diffraction peak. The purpose of the ; experiment was to examine the behavior of the largeangle differential elastic ; cross section as a function of energy from the energy of the highest known ; resonance in the pion-nucleon system into the region where the total. cross ; sections appear to be approaching an asymptotic value. The experiment was ; performed at the Bevatron, using a luminescent chamber system to photograph the ; tracks of the scattered pion and the recoil proton from a liquid hydrogen target. ; A total of 2412 elastic scatterings were analyzed at 1.51 Bev/c, 1300 events at ; 2.01 Bev/c, and 1080 events at 2.53 Bev/c. From the existing data it may be ; noted that the backward bump, which has a maximum height of 2.1 mb/sr at 900 Mev ; and 1.1 mb/sr at 1020 Mev, is down to 0.4 mb/sr at 1.51 Bev/c (1.37 Bev), and is ; not present at 2.01 or 2.53 Bev/c. The angular distributions behind the ; diffraction peak at 2.01 and 2.53 Bev/c are rougly constant, decreasing from 0.18 ; mb/sr at 2.01 Bev/c to 0.125 mb/sr at 2.53 Bev/c. Although the data can be taken ; to suggest some oscillatory structure in this region, they are not inconsistent ; with an isotropic distribution that might be interpreted as evidence for an S-; wave scattering behind the diffraction peak. Large-Angle Elastic Scattering of Negative Pions by Protons at 1.51, 2.01, and 2.53 Bev/c.
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RADIATIVE TAILS OF PSI RESONANCES HAVE BEEN REMOVED. SIG(HAD) IS NOT TABULATED FOR 4.0 TO 4.4 GEV AS THE DATA POINTS ARE TOO CLOSE TO DISTINGUISH FROM THE GRAPH.
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RE/IM MEASUREMENTS TAKEN FROM TABLE 1 OF KIRILLOVA 65.
TABLE 1 (REF. 1 ).
RE/IM MEASUREMENTS TAKEN FROM TABLE 1 OF KIRILLOVA 65.
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In a bubble chamber experiment, we have measured p p elastic scattering at nine momenta in the range 1.51–2.90 GeV/ c . The extrapolation of the small angle region to t = 0 is discussed and compared with results of other experiments. The differential cross sections are fitted to an adaptation of the Frahn-Venter optical model and also compared to Regge-pole model predictions.
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