Photoproduction of mesons off light nuclei

In a series of experiments at the tagged photon facilities of the Bonn ELSA accelerator and the Mainz MAMI accelerator photo production of mesons from light nuclear targets (deuteron, He-3) has been studied. The experiments used the combined Crystal Barrel/TAPS setup in Bonn and the Crystal Ball/TAPS setup in Mainz. Meson photoproduction off the neutron has been investigated for the pi degrees, pi degrees pi degrees, pi degrees pi(-), eta, eta`, and eta pi degrees final states. A surprising finding was a narrow structure in the gamma n -< nn excitation function, which is not seen in the proton case. Measurements of eta- and pi degrees-photoproduction off a liquid He-3-target have provided further evidence for the formation of eta-mesic He-3.