Differential cross sections have been measured for the interactions p p → π − π + and p p → K − K + over a centre of mass angular range −0.95 ⩽ cos θ ∗ ⩽ 0.95 at 20 incident momenta between 0.79 and 2.43 GeV/ c . A magnetic spectrometer with wire spark chambers was used. Typically 2000 π − π + and 300 K − K + events were obtained at each momentum. Results are compared with those from related experiments.
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Inclusive hadron production in muon-proton inelastic scattering has been measured for q2>0.5 (GeV/c)2 and 10<ν<135 GeV. The results are presented in the form of the transverse momentum distribution of charged hadrons and the hadron invariant structure function F(x′). Results are given for different regions of q2 and s.
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Differential cross sections for the photoproduction of pi-zero mesons from protons have been measured at angles between 10° and 70° c.m. in the energy range 0.85 GeV to 1.30 GeV. The values are compared with the fits to pion photoproduction data from three recent partial-wave analyses.
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Measurements of differential cross sections for pi-zero photoproduction from protons have been made at angles between 60° and 140° c.m. in the photon energy range 0.7 GeV to 1.7 GeV. The data are compared with the rits provided by three recent partial-wave analyses of pion photoproduction and some significant discrepancies observed.
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We present measurements from a spark chamber experiment of the differential cross-sections for p p → π − π + , K − K + at 20 momenta in the range 0.8–2.4 GeV/ c (c.m. energy 2.02 to 2.57 GeV). The c.m. angular range was −0.95 < cos θ ∗ < 0.95 . There are about 2000π − π + events and about 300 K − K + events at each momentum.
ALL ANGLES.
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.
The polarization parameter in π − p elastic scattering has been measured in the backward angular region at an incident momentum of 6 GeV/ c . The measurements cover the range of four momentum transfer u = 0 to −1 (GeV/ c ) 2 , and were obtained with a high intensity pion beam, a butanol polarized proton target, and arrays of scintillation counter hodoscopes. The polarization is different from zero, in contradiction to the prediction of the naive one trajectory Regge-exchange model. It increases positively with the four-momentum transfer u, reaching a maximum of about 0.4 at u ≈ −0.3 (GeV/c)2. It then decreases and becomes slightly negative beyond u ≈ −0.5 (GeV/c)2. A variety of baryon exchange models are briefly reviewed and none are found to be in complete agreement with all the experimental data.
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We have measured the cross section, the angular distribution, and the Λ polarization for the reaction π−p→ΛK0. A spark-chamber spectrometer was used to collect 8400 ΛK0 events at fourteen beam momenta near ΣK threshold. Our data do not show the prominent cross-section enhancement suggested by some previous experiments. However, detailed structure in the cross section and the angular distribution agrees well with a simple model which includes a cusp effect at ΣK threshold.
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BACKWARD-FORWARD PRODUCTION ASYMMETRY.
AVERAGE LAMBDA POLARIZATION.
In an experiment at the Argonne Zero-Gradient Synchrotron we have measured values of the polarization parameter P(t) in the elastic scattering of negative pions, positive pions, positive kaons, and protons on protons at several incident laboratory momenta from 2.50 to 5.15 GeVc, and for values of the momentum transfer variable −t from 0.2 to 2.0 (GeVc)2. The final results from p−p elastic scattering presented here extend our knowledge of the polarization to much larger values of −t than the results of previous measurements. Outstanding features revealed by these polarization data include (1) the development of a dip at about −t=0.7 (GeVc)2, with (2) a substantial secondary peak at larger values of −t and (3) the gradual diminution of the maximum polarization with increasing energy. It is possible to fit the t dependence of the experimental results with a simple model. The energy dependence of the polarized cross sections is also discussed.
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We have used an optical spark-chamber spectrometer to perform a systematic study of the reaction π−p→ΛK0 at beam momenta between 930 and 1130 MeV/c. The cross section, angular distribution, and Λ polarization have been measured. We present our complete data from a sample of 11 400 events along with Legendre polynomial coefficients for the angular distributions. No striking cross-section enhancement at ΣK threshold is observed, but there is evidence for a small cusp effect. A simple model which takes account of the ΣK channel provides a good fit to our data.
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