  Isolated photon production is measured in pp and PbPb collisions at
nucleon-nucleon centre-of-mass energies of 2.76 TeV in the pseudorapidity range
|eta|<1.44 and transverse energies E_T between 20 and 80 GeV with the CMS
detector at the LHC. The measured E_T spectra are found to be in good agreement
with next-to-leading-order perturbative QCD predictions. The ratio of PbPb to
pp isolated photon E_T-differential yields, scaled by the number of incoherent
nucleon-nucleon collisions, is consistent with unity for all PbPb reaction
centralities.
