  We constrain the average density profile of the proton and the amount of
event-by-event fluctuations by simultaneously calculating the coherent and
incoherent exclusive diffractive vector meson production cross section in deep
inelastic scattering. Working within the Color Glass Condensate picture, we
find that the gluonic density of the proton must have large geometric
fluctuations in order to describe the experimentally measured large incoherent
cross section.
