Analysis and First Results of the Helicity Dependent Double-Pion Production at MAMI

During the GDH experiment at MAMI, helicity-dependent photoproduction cross-section differences σ_3/2 - σ_1/2 have been measured on the proton. In addition to the partial channels Nπ and Nη we have extracted the cross-section differences for the three possible Nππ isospin channels to get the full set of helicity-dependent data in the range between ππ threshold and 800 MeV photon energy. The partial Nπ channels have to be reliably separated in order to avoid backgrounds. Methods are presented here and first preliminary results are shown for the helicity-dependent double-pion photoproduction for vec γ {vec p} -> {p}π ^ + π ^ - and vec γ {vec p} -> {n}π ^ + π ⁰ .