Determination of polarization observables in the π0 and ω photoproduction on the proton with the CBELSA/TAPS

The goal of the CBELSA/TAPS-experiment is the investigation of the nucleon-resonance-structure. It turns out that the measurement of polarisation-observables is indispensable. These observables are measured using linearly or circularly polarised photons and a polarised target. The preparation and characterisation of linearly polarised photons was part of this work. Linearly polarised photons were produced by coherent bremsstrahlung from an accurately aligned diamond crystal at deliberately chosen photon energies and polarisation planes. The degree of polarisation was determined with a maximum relative uncertainty of 5% in a wide energy-range. The precision of the determined degree of linear polarisation could be verified by the extraction of the polarisation observable Σ in the reaction γp → pπ0. Furthermore the double-polarisation-observable G was determined by the investigation of this reaction using linearly polarised photons and a longitudinally polarised target. The results for the observable G better constrain resonance properties contributing to this channel than it was possible before. The main focus of this thesis was the investigation of the reaction γp → pω. For this purpose the observables Σ and Σπ as well as for the first time the double-polarisation-observables G, Gπ and E were determined. In particular the results for the high-statistics measurements of the observable E provide strong evidence for the production of the ω-meson via the decay of resonances in the s-channel.