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2008
Journal Article
Title
Photoproduction of eta-mesons off nuclei for Egamma <= 2.2 GeV
Abstract
The photoproduction of eta-mesons off 12C, 40Ca, 93Nb, and natPb nuclei has been measured with a tagged photon beam with energies between 0.6 and 2.2 GeV. The experiment was performed at the Bonn ELSA accelerator with the combined setup of the Crystal Barrel and TAPS calorimeters. It aimed at the in-medium properties of the S11(1535) nucleon resonance and the study of the absorption properties of nuclear matter for eta-mesons. Careful consideration was given to contributaions from etapi final states and secondary production mechanisms of eta-mesons, e.g. from inelastic pi Eta reactions of intermediate pions. The analysis of the mass number scaling shows that the nuclear absorption cross-section sigmaNyeta for eta-mesons is constant over a wide range of the eta momentum. The comparison of the excitation functions to data off the deuteron and to calculations in the framework of a BUU model show no unexplained in-medium modifications of the S11(1535).
Author(s)
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
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
Thoma, U.
Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn, Germany / II. Physikalisches Institut, Universität Giessen, Germany