Helicity dependence of the γHe-3 -< τX reactions in the δ¹²³² resonance region

The helicity dependence of the differential cross-section for the gamma d -> pi NN reactions has been measured for the first time in the Delta-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 pi(+/-) NN channels are the quasi-free N pi processes on one bound nucleon with nuclear dynamics playing a minor role. On the contrary, for the pi(0)np channel nuclear mechanisms involving the reabsorption of the photoproduced pi(0) by the np pair have to be taken into account to reproduce the experimental data.