  Using data recorded in 2011 with the ATLAS detector at the Large Hadron
Collider, a search for evidence of extra spatial dimensions has been performed
through an analysis of the diphoton final state. The analysis uses data
corresponding to an integrated luminosity of 2.12 fb^-1 of sqrt(s) = 7 TeV
proton-proton collisions. The diphoton invariant mass spectrum is observed to
be in good agreement with the expected Standard Model background. In the large
extra dimension scenario of Arkani-Hamed, Dimopoulos and Dvali, the results
provide 95% CL lower limits on the fundamental Planck scale between 2.27 and
3.53 TeV, depending on the number of extra dimensions and the theoretical
formalism used. The results also set 95% CL lower limits on the lightest
Randall-Sundrum graviton mass of between 0.79 and 1.85 TeV, for values of the
dimensionless coupling k/\bar{M}_{Pl} varying from 0.01 to 0.1. Combining with
previously published ATLAS results from the dielectron and dimuon final states,
the 95% CL lower limit on the Randall-Sundrum graviton mass for k/\bar{M}_{Pl}
= 0.01 (0.1) is 0.80 (1.95) TeV.
