A direct measurement of the helicity dependence of the total photoabsorption cross section on the proton was carried out at MAMI (Mainz) in the energy range 200<Eγ<800 MeV. The experiment used a 4π detection system, a circularly polarized tagged photon beam, and a frozen spin target. The contributions to the Gerasimov-Drell-Hearn sum rule and to the forward spin polarizability γ0 determined from the data are 226±5(stat)±12(syst) μb and -187±8(stat)±10(syst)×10-6 fm4, respectively, for 200<Eγ<800 MeV.
ASJC Scopus subject areas
- Physics and Astronomy(all)