https://doi.org/10.1140/epja/i2007-10667-y
Regular Article - Experimental Physics
Photoproduction of η -mesons off nuclei for Eγ ⩽ 2.2 GeV
1
Department Physik, Universität Basel, Basel, Switzerland
2
Institut für Theoretische Physik I, Universität Giessen, Giessen, Germany
3
KVI, University of Groningen, Groningen, The Netherlands
4
Physikalisches Institut der Universität Bonn, Bonn, Germany
5
Helmholtz-Institut für Strahlen- und Kernphysik der Universität Bonn, Bonn, Germany
6
Petersburg Nuclear Physics Institute, Gatchina, Russia
7
Department of Physics, Florida State University, Tallahassee, USA
8
II. Physikalisches Institut, Universität Giessen, Giessen, Germany
* e-mail: Bernd.Krusche@unibas.ch
Received:
21
December
2007
Revised:
12
September
2008
Accepted:
13
October
2008
Published online:
30
October
2008
The photoproduction of η -mesons off 12C , 40Ca , 93Nb , and
nat
Pb nuclei has been measured with a tagged photon beam with energies between 0.6 and 2.2GeV. 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 S
11(1535) nucleon resonance and the study of the absorption properties of nuclear matter for η -mesons. Careful consideration was given to contributions from ηπ final states and secondary production mechanisms of η -mesons, e.g. from inelastic πN reactions of intermediate pions. The analysis of the mass number scaling shows that the nuclear absorption cross-section 
for η -mesons is constant over a wide range of the η 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 S
11(1535) .
PACS: 13.60.Le Meson production – / 14.20.Gk Baryon resonances with S = 0 – / 25.20.Lj Photoproduction reactions –
© SIF, Springer-Verlag Berlin Heidelberg, 2008
