Helicity dependence of the d NN reactions in the -resonance region

The helicity dependence of the differential cross-section for the d NN reactions has been measured for the first time in the -resonance region. The measurement was performed with the large-acceptance detector DAPHNE at the tagged photon beam facility of the MAMI accelerator in Mainz. The data show that the main reaction mechanisms for the NN channels are the quasi-free N processes on one bound nucleon with nuclear dynamics playing a minor role. On the contrary, for the np channel nuclear mechanisms involving the reabsorption of the photoproduced by the np pair have to be taken into account to reproduce the experimental data.