Cross-sections and spin observables in proton-proton elastic scattering: Results from EDDA at COSY
Helmholtz-Institut für Strahlen- und Kernphysik, Universität Bonn, D-53115, Bonn, Germany
2 Institut für Experimentalphysik, Universität Hamburg, D-22761, Hamburg, Germany
3 Institut für Kernphysik, Forschungszentrum Jülich, D-52425, Jülich, Germany
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At the Cooler-Synchrotron COSY/Jülich polarized and unpolarized elastic proton-proton scattering has been investigated with the EDDA-Experiment in the energy range (-2.5 GeV). By taking scattering data during the acceleration of the beam with a large-acceptance (-) detector, precise excitation functions for differential cross-section and analyzing power have been measured in small energy steps with consistent normalization with respect to luminosity and polarization. These data have helped to improve the determination of phase-shifts at higher energies and impose tight quantitative upper bounds on possible resonant contributions to pp elastic scattering, as they might arise from exotic 6-quark configurations. Recently, with polarized beam and target, the spin-correlation parameters , , and have been determined at 10 energies between 0.8 and 2.5 GeV. The observable has been measured the first time above 800 MeV and our results are in sharp contrast to phase-shift predictions at higher energies.
© Società Italiana di Fisica and Springer-Verlag, 2003