  Coherent vector meson production in peripheral nucleus-nucleus collisions is
discussed. These interactions may occur for impact parameters much larger than
the sum of the nuclear radii. Since the vector meson production is always
localized to one of the nuclei, the system acts as a two-source interferometer
in the transverse plane. By tagging the outgoing nuclei for Coulomb
dissociation it is possible to obtain a measure of the impact parameter and
thus the source separation in the interferometer. This is of particular
interest since the life-time of the vector mesons are generally much shorter
than the impact parameters of the collisions.
