  Fragmentation of nuclear system by tunneling is discussed in a molecular
dynamics simulation coupled with imaginary time method. In this way we obtain
informations on the fragmenting systems at low densities and temperatures.
These conditions cannot be reached normally (i.e. above the barrier) in
nucleus-nucleus or nucleon-nucleus collisions. The price to pay is the small
probability of fragmentation by tunneling but we obtain observables which can
be a clear signature of such phenomena.
