The K − p reactions leading to charge exchange and hyperon final states have been studied at nine momenta between 862 and 1001 MeV/ c using data from a 600 000 picture exposure of the Lawrence Berkeley Laboratory 25″ liquid hydrogen bubble chamber. Partial cross sections are determined for all final states resolved by kinematic fitting. In addition, differential cross sections are presented for the two-body final states K o n , Λπ o and Σ +- π -+ along with hyperon polarization angular distributions for Λπ o and Σ + π − .
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The target asymmetry T = ( σ ↑ − σ ↓)/( σ ↑ + σ ↓) for the reaction γ p → π + n has been measured at the Bonn 2.5 GeV electron synchrotron for a pion c.m. angle of 40° and γ energies between 0.5 and 2.2 GeV. Butanol was used as the target material. About 35% of the protons could be polarized using the dynamic-polarization method in a continuous-flow cryostat operating at 1°K and 25 kG. The π + mesons were detected in a magnetic-spectrometer system. Considerable structure in the asymmetry was observed.
Axis error includes +- 11/11 contribution.
The differential cross section has been measured for the reaction γ +p→p+ π o at the Bonn 2.5 GeV electron synchrotron in the energy range from 0.4 to 2.2 GeV for a c.m. angle of 150 degrees. The protons were detected in a magnetic spectrometer system. The excitation curve shows a distinct resonance structure. The total corrections to the counting rate are about 3%. The contribution of the process γ +p→p+2 π was separated. The uncertainty of this separation leads to an error of about 4% in the cross section.
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The twofold differential cross section for the inelastic scattering of electrons on protons wa was measured as a function of the scattered electron energy for an electron scattering angle of 12°. The kinematic region covered in this experiment was 0.3 (GeV/ c ) 2 < q 2 < 1.0 (GeV/ c ) 2 and W < 2.9 GeV. The Bloom-Gilman as well as the constant scattering angle sum rule of Rittenberg and Rubinstein were tested.
Axis error includes +- 0.0/0.0 contribution (3.7 TO 5////UNCERTAINTIES IN TARGET DENSITY, TARGET DIAMETER, SOLID ANGLE, E- SCATTERING ANGLE, INCIDENT E- ENERGY, DEAD TIME CORRECTIONS, CONSTANT OF FARADAY-CUP INTEGRATOR EFFICIENCY OF SPARK CHAMBERS, RADIATIVE CORRECTIONS).
Axis error includes +- 0.0/0.0 contribution (3.7 TO 5////UNCERTAINTIES IN TARGET DENSITY, TARGET DIAMETER, SOLID ANGLE, E- SCATTERING ANGLE, INCIDENT E- ENERGY, DEAD TIME CORRECTIONS, CONSTANT OF FARADAY-CUP INTEGRATOR EFFICIENCY OF SPARK CHAMBERS, RADIATIVE CORRECTIONS).
Axis error includes +- 0.0/0.0 contribution (3.7 TO 5////UNCERTAINTIES IN TARGET DENSITY, TARGET DIAMETER, SOLID ANGLE, E- SCATTERING ANGLE, INCIDENT E- ENERGY, DEAD TIME CORRECTIONS, CONSTANT OF FARADAY-CUP INTEGRATOR EFFICIENCY OF SPARK CHAMBERS, RADIATIVE CORRECTIONS).
We measured the elastic and inelastic scattering of electrons on deuterium at 180° for four incident energies (70, 140, 210 and 280 MeV). The data were analysed with a technique allowing an accurate comparison between experiment and theory. We observed a good agreement for the inelastic data with the expected cross section, using the presently available models and nucleon form factors. The experimental elastic cross section is systematically larger than the predicted cross sections.
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41 ± 8 events of the type X 0 → γγ have been observed in a study of the reaction π − p → n(X 0 → γγ ) at 1.6 GeV/ c incident π -momentum. This provides further evidence to our previous observation of this new X 0 decay mode and allows the determination of the branching ratio Γ(X 0 →γγ) Γ(X 0 → total =(1.7 ± 0.4)%. The theoretical implications of this result are discussed.
THIS MEASUREMENT WHEN COMBINED WITH THE ETAPRIME PRODUCTION CROSS SECTION OF M. BASILE ET AL., NC 3A, 371 (1971) YIELDS A BR(ETAPRIME --> 2GAMMA) OF 1.7 +- 0.4 PCT.
Measurements on large-angle photoproduction of π+ mesons from hydrogen have been made at the Stanford Linear Accelerator Center for photon energies between 5 and 15.5 GeV and u values from +0.05 to -1.8 (GeV/c)2. The measured cross section decreased with energy approximately as k−3, showing no shrinkage in this range of u values. Furthermore, it had a smooth u dependence with no sign of a dip at u≃−0.15 (GeV/c)2 as would be expected from nucleon exchange. π−Δ++ production was measured at 5 GeV and shows a rapid decrease with increasing |u|.
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