Options
2007
Journal Article
Titel
Measurement of the beam asymmetry in eta photoproduction off the proton
Abstract
The beam asymmetry, Sigma, was measured at ELSA in the reaction gammaroh -> etaroh using linearly polarised tagged photon beams, produced by coherent bremsstrahlung off a diamond. The crystal was oriented to provide polarised photons in the energy range Egamma = 800 to 1400 MeV with the maximum polarisation of Pgamma = 49% obtained at 1305 MeV. Both dominant decay modes of the eta into two photons and 3pi0 , were used to extract the beam asymmetry from the azimuthal modulation of the cross-section. The measurements cover the angular range Thetacm -~ 50-150 degrees. Large asymmetries up to 80% are observed, in agreement with a previous measurement. The eta-MAID model and the Bonn-Gatchina partial wave analysis describe the measurements, but the required partial waves differ significantly.
Author(s)
Anisovich, A.V.
Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn, Germany / Petersburg Nuclear Physics Institute, Gatchina, Russia
Bayadilov, D.
Helmholtz-Institut für Strahlen- u. Kernphysik Universität Bonn, Germany / Petersburg Nuclear Physics Institute Gatchina, Russia
Crede, V.
Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn, Germany / Department of Physics, Florida State University, Tallahassee, FL, USA
Kotulla, M.
Department Physik, Universität Basel, Switzerland / II. Physikalisches Institut, Universität Giessen, Germany
Nikonov, V.A.
Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn, Germany / Petersburg Nuclear Physics Institute, Gatchina, Russia
Novinski, D.V.
Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn, Germany / Petersburg Nuclear Physics Institute, Gatchina, Russia
Pee, H. van
Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn, Germany / II. Physikalisches Institut, Universität Giessen, Germany
Sarantsev, A.V.
Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn, Germany / Petersburg Nuclear Physics Institute, Gatchina, Russia
Thoma, U.
Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn, Germany / II. Physikalisches Institut, Universität Giessen, Germany