No abstract available

[en] When a polarized target is used in conjunction with a high energy and high intensity photon beam, radiation damage of the target material causes some severe experimental problems. This paper is concerned with one of these problems, the effect that radiation damage has on the systematic uncertainties in the measurement of the effective target polarization, as applied to the programme of photoproduction measurements recently completed at the 5 GeV NINA electron synchrotron. It is shown that the effect of a non-uniform radiation damage profile combined with a non-uniform sampling of the target material by the NMR system used to measure the polarization, can introduce large systematic uncertainties. Radiation damage profiles have been calculated for a range of different experimental situations used in the programme and confirmed in one particular case by experimental measurements. The NMR sampling efficiency profiles have also been determined experimentally and corrections to the measured polarization values obtained using the calculated radiation damage profiles. The corrections were found to be less than 2% for the normal experimental operating conditions. (orig.)

No abstract available

[en] Measurements have been made of the target asymmetry parameter for photoproduction of π⁰ mesons from protons, using a butanol polarised target with a ³He cryostat. Results were obtained at 14 incident photon energies between 0.7 GeV and 1.45 GeV over an angular range approximately 40⁰ to 145⁰ c.m. The recent analysis of Barbour and Crawford provides a very good fit to the data. (Auth.)

[en] Measurements have been made of the polarisation parameters G and H for the process γp → π⁺n in the photon energy range 600-1875 MeV and pion c.m. angles between 30⁰ and 100⁰. These data were obtained in a double polarisation experiment, in which the polarised photon beam from the Daresbury electron synchrotron was incident upon a polarised proton target. Theoretical predictions from a current analysis are compared with the data. (orig.)

[en] Measurements have been made of the double polarisation parameters G and H in the photoproduction of neutral pions from protons, for incident photon energies between 1300 MeV and 2300 MeV and for pion c.m. angles between 50⁰ and 80⁰. The results are compared with predictions from a recent comprehensive analysis of earlier photoproduction data. (Auth.)

[en] The polarization parameters Σ, P and T have been measured for the process γp → π⁰p in the photon energy range 1300-2100 MeV and c.m. angles between 30⁰ and 110⁰, in an experiment with a polarised beam and polarised target. The results are compared with a recent theoretical analysis which fits data from threshold to 16 GeV. The new data are in general agreement with the analysis, but with some significant discrepancies in detail. (Auth.)

[en] Measurements have been made of the polarisation parmeters Σ, T and P for the process γp → π⁺n in the photon energy range 520-2250 MeV at c.m. angles between 30⁰ and 120⁰. These data were obtained in a double polarisation experiment, using the polarised photon beam from the Daresbury electron synchrotron incident on a polarised proton target. The data are compared with predictions from current theoretical analyses. (Auth.)

[en] The design and instrumentation of a streamer tube detector for operation in the high rate environment of the CPLEAR experiment at CERN is described. A study of gas mixtures for use in the streamer tube is discussed. The final mixture of 46% argon, 50% isobutane, 4% methylal and 0.01% freon produces an axial resolution of 1.5 cm with an efficiency of 98% per layer. (orig.)

[en] We report the results of the CPLEAR experiment on CP-, T- and CPT-symmetries in the neutral kaon system. CP-violation parameters are given for different decay channels. For the first time T-violation is measured by a direct method using semileptonic decays. The CPT symmetry in the kaons decays is tested through the parameters Im(δ), from the Bell-Steinberger relation, with a precision of 10^-5 and Re(δ) with a precision of a few 10^-4 (two order of magnitude better than the previous measurement). These two measurements allow us to bound the difference in mass and width of K⁰ and K-bar⁰ to be equal within 10^-18 GeV. In the limit of CPT invariance in the neutral kaon decays, the K⁰ and K-bar⁰ masses are equal within 10^-19 GeV