Gießen 2007 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 11: Elektromagnetische und Hadronische Sonden
HK 11.5: Talk
Tuesday, March 13, 2007, 15:15–15:30, A
πoπo, η and η′ photoproduction off deuteron — •Igal Jaegle for the CBELSA-TAPS collaboration — Department für Physik und Astronomie Universität Basel Klingelbergstrasse 82 CH-4056 Basel
A simultaneously study of πoπo, 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 (exclusice measurement), so that the reaction on the neutron is measured in 2 different ways. At 1700 MeV mass location, the πoπo 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. This work is supported by the Swiss National fund.