  While Josephson-like junctions, transiently established in heavy ion
collisions ($\tau_{coll}\approx10^{-21}$ s) between superfluid nuclei --through
which Cooper pair tunneling ($Q$-value $Q_{2n}$) proceeds mainly in terms of
successive transfer of entangled nucleons-- is deprived from the macroscopic
aspects of a supercurrent, it displays many of the special effects associated
with spontaneous symmetry breaking in gauge space (BCS condensation), which can
be studied in terms of individual quantum states and of tunneling of single
Cooper pairs. From the results of studies of one- and two- neutron transfer
reactions carried out at energies below the Coulomb barrier we estimate the
value of the mean square radius (correlation length) of the nuclear Cooper
pair. A quantity related to the largest distance of closest approach for which
the absolute two-nucleon tunneling cross section is of the order of the
single-particle one. Furthermore, emission of $\gamma$-rays of (Josephson)
frequency $\nu_J=Q_{2n}/h$ distributed over an energy range $\hbar/\tau_{coll}$
is predicted.
