  A search for diphoton events with large missing transverse energy is
presented. The data were collected with the ATLAS detector in proton-proton
collisions at sqrt(s) = 7 TeV at the CERN Large Hadron Collider and correspond
to an integrated luminosity of 3.1/pb. No excess of such events is observed
above the Standard Model background prediction. In the context of a specific
model with one Universal Extra Dimension with compactification radius R and
gravity-induced decays, values of 1/R < 728 GeV are excluded at 95% CL,
providing the most sensitive limit on this model to date.
