Photoproduction of eta-mesons off nuclei for Eg < 2.2 GeV

Abstract

Photoproduction of $\eta$ mesons off ${}^{12}$C, ${}^{40}$Ca, ${}^{93}$Nb, and ${}^{nat}$Pb 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 S${}_{11}$(1535) nucleon resonance and the study of the absorption properties of nuclear matter for $\eta$ mesons. Careful consideration was given to contributions from $\eta \pi$ final states and secondary production mechanisms of $\eta$-mesons e.g. from inelastic $\pi N$ reactions of intermediate pions. The analysis of the mass number scaling shows that the nuclear absorption cross section ${\sigma }_{N\eta }$ 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 S${}_{11}$(1535).

Accepted for publication in Eur. Phys. J. A

References in corpus (7)

• Evidence for a narrow structure at W~1.68 GeV in eta photoproduction on the neutron
• Modification of the $\omega$-Meson Lifetime in Nuclear Matter
• Measurement of the beam asymmetry in eta-photoproduction off the proton
• Quasi-free photoproduction of eta-mesons of the neutron
• Photoproduction of pi0-mesons from nuclei
• Double pion photoproduction off 40Ca
• Surface and volume effects in the photoabsorption of nuclei

Cited by in corpus (5)

• Meson-nucleus potentials and the search for meson-nucleus bound states
• Formation of eta-mesic nuclei by (pi,N) reaction and N^*(1535) in medium
• Pionic transparency in semi-exclusive electroproduction off nuclei
• Search for ${\eta }^{\prime }$ bound nuclei in the ${}^{12}\mathrm{C}(\gamma ,p)$ reaction with simultaneous detection of decay products
• Exploring QCD dynamics in medium energy $\gamma A$ semiexclusive collisions