  New reaction mechanisms occurring in heavy ion collisions at low energy (10-
30 MeV/A) are investigated within the Stochastic Mean Field model. We
concentrate on the analysis of ternary breakup events, of dynamical origin,
occurring in semi-central reactions, where the formation of excited systems in
various conditions of shape and angular momentum is observed. We show how this
fragmentation mode, which can be considered as a precursor of the neck emission
observed at higher beam energies, emerges from the combined action of surface
(neck) instabilities and angular momentum effects. Interesting perspectives are
opening towards the investigation of this mechanism in neutron-rich (or exotic)
systems, with the possibility to access information on the low-density behavior
of the nuclear symmetry energy.
