Photoproduction of Mesons off Light Nuclei -- the Search for η-Mesic Nuclei

Photoproduction of ηmesons off light nuclei (d, 3He, 7Li) has been measured at the tagged photon beam of the Mainz MAMI accelerator with the combined Crystal Ball/TAPS detection system. Special attention was given to the threshold behavior of the reactions in view of possible indications for the formation of (quasi-) bound η-nucleus states, so-called η-mesic nuclei. A very strong threshold enhancement of coherent ηphotoproduction off 3He was found and coherent ηphotoproduction off 7Li was observed for the first time. Preliminary results will be discussed.