  Isospin transport phenomena in dissipative heavy ion collisions have been
investigated at Fermi energies with a beam of 84Kr at 35AMeV. A comparison of
the <N>/Z of light and medium products forward-emitted in the centre of mass
frame when the beam impinges on a n-poor 112Sn and a n-rich 124Sn targets is
presented. Data were collected by means of a three-layer telescope with very
good performances in terms of mass identification (full isotopic resolution up
to Z about 20 for ions punching through the first detector layer) built by the
FAZIA Collaboration and located just beyond the grazing angle for both
reactions. The <N>/Z of the decay products emitted when the n-rich target is
used is always higher than that associated to the n-poor one. Since the
detector was able to measure only fragments coming from the QuasiProjectile
decay and/or neck emission, the observed behaviour can be ascribed to the
isospin diffusion, driven by the isospin gradient between QuasiProjectile and
QuasiTarget. Moreover, for light fragments the <N>/Z as a function of the lab
velocity of the fragment increases when we move from the QuasiProjectile
velocity to the centre of mass (neck zone). This effect can be interpreted as
an evidence of isospin drift driven by the density gradient between the
QuasiProjectile zone (at normal density) and the more diluted neck zone.
