The use of a circularly polarized photon beam and a longitudinally polarized nucleon target gives access to the helicity dependent cross sections, which were unmeasured before lacking the technical developments that only recently have taken place. These new observables make possible the experimental veri¿cation of the Gerasimov-Drell-Hearn (GDH) sum rule, which yields a direct link between the dynamical excitation spectrum of the target particle and it¿s static properties: the anomalous magnetic moment, spin and mass. Because of its fundamental character, this prediction provides a basic test of our knowledge of the ¿N interaction and of the spin structure of the nucleon. The experimental setup for the GDH sum rule verification on the neutron, data analysis and results are shown in this work.