Nuclear geometry at high energy from exclusive vector meson production

We show that when saturation effects are included one obtains a good description of the exclusive $\mathrm{J}/\ensuremath{\psi}$ production spectra in ultraperipheral lead-lead collisions as recently measured by ALICE Collaboration at LHC. As sensitive to spatial distribution nuclear matter small Bjorken-$x$, this implies gluon modify impact parameter profile target we move towards $x$. In addition effects, find preference for larger strong-interaction radii compared typical charge radius. demonstrate role finite photon transverse momentum and interference between cases which emitter switched nuclei. these comparable experimental precision ${p}_{T}$-differential cross sections such need be comparing LHC data. Finally, integrated from preliminary RHIC shown prefer calculations with fluctuating nucleon substructure, although datasets would require even stronger than predicted our framework.