Measurement of the double polarization observable E in η'-photoproduction

The goal of the CBELSA/TAPS experiment located at the electron stretcher accelerator ELSA lies in the better understanding of the dynamics of the nucleon constituents by investigating the nucleon excitation spectrum through photoproduction of mesons off the nucleon. The study of η'-photoproduction gives information of the high mass region (m_N^* >1892 MeV) of the nucleon excitation spectrum which is poorly understood. In order to determine all contributing resonances in the underlying process, the measurement of well chosen single and double polarization observables apart from the unpolarized cross section is needed. For this purpose, a linearly or circularly polarized photon beam and longitudinally or transversely polarized target are used at the CBELSA/TAPS experiment. The setup provides with the Crystal Barrel and the MiniTAPS calorimeters a nearly full 4π angular coverage and has therefore a high detection efficiency for neutral final states. In this talk, preliminary results of the double polarization observable E in the photoproduction reaction γp → η'p are presented.