  The problem of characterizing the origin of the non-Gaussian properties of
transport resulting from Hamiltonian dynamics is addressed. For this purpose
the notion of chaotic jet is revisited and leads to the definition of a
diagnostic able to capture some singular properties of the dynamics. This
diagnostic is applied successfully to the problem of advection of passive
tracers in a flow generated by point vortices. We present and discuss this
diagnostic as a result of which clues on the origin of anomalous transport in
these systems emerge.
