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First measurement of the Gerasimov-Drell-Hearn integral for Hydrogen from 200 to 800 MeV

GDH-Collaboration·A2-Collaboration·:·J. Ahrens
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Abstract

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 < E_gamma < 800 MeV. The experiment used a 4$π$ 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 $γ_0$ determined from the data are 226 \pm 5 (stat)\pm 12(sys) μb and -187 \pm 8 (stat)\pm 10(sys)10^{-6} fm^4, respectively, for 200 < E_γ< 800 MeV.

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GDH-Collaboration, A2-Collaboration, :, J. Ahrens. 2001-06-26. First measurement of the Gerasimov-Drell-Hearn integral for Hydrogen from 200 to 800 MeV. https://doi.org/10.1103/physrevlett.87.022003

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