Experimental check of the GDH sum rule at MAMI and ELSA Original Research Article

An extensive experimental program was carried out at MAMI (Mainz) and ELSA (Bonn) to measure pion photo-production reactions on the nucleon in double polarization and to investigate the Gerasimov-Drell-Hearn Sum Rule. We obtained results for the proton in the energy range from about 200 MeV to 3000 MeV and for the neutron, using a deuteron target, from about 200 MeV to 1900 MeV. Preliminary results on the total absorption cross sections are presented and discussed.