π0π0, η and η' photoproduction off deuteron

A simultaneously study of π0π0, η and η' photoproduction off deuteron has been done at the tagged photon beam of the Bonn ELSA accelerator with a combined setup of the Crystal Ball and TAPS detectors, which formed a 4π electromagnetic calorimeter. The aim of the study is to observe and identify individual N* and Δ states of masses between 1.5GeV and 2.2GeV with strong photocouplings to the neutron. The mesons were detected alone (inclusive measurement) or in coincidence with the (participant) recoil nucleons (exclusive measurement), so that the reaction on the neutron is measured in 2 different ways. At 1700 MeV mass location, the π0π0 and η mesons neutron - proton cross section ratios show a strong rise. At 2000 MeV mass location, the η' meson neutron - proton cross section ratio is constant. The fermi motion effect was estimated and removed. No narrow enhancement was observed for the ηn - channel as predicted by different models that include the non-strange member of the anti-decuplet. All the reactions can be explained within frameworks that use known resonances. (orig.)