Photoexcitation of baryon resonances on nucleons and nuclei : an example : recent results from photoproduction of η-mesons

Photoproduction of eta-mesons off the proton, the deuteron and other light nuclei, and off heavy nuclei has been studied in detail during the last decade at the electron accelerators MAMI in Mainz, ELSA in Bonn, ERSF in Grenoble, CEBAF in Newport News, at KEK, and at Tohoku. The physics topics range from the detailed investigation of the properties of known nucleon resonances (in particular S-11(1535)), over the search of new states, to the in-medium properties of baryon resonances, and the possible formation of eta-nucleus (quasi)bound states (eta-mesic nuclei). It is thus an excellent example for the different aspects of the photoexcitation of nucleon resonances. Here we report new preliminary results from the CBELSA/TAPS experiment for this reaction at higher incident photon energies for the deuteron and heavy nuclei.