Isolated Photon Reconstruction and Identification at sqrt{s

We present the performance of isolated photon reconstruction and identification in the CMS experiment. The data sample corresponds to an integrated luminosity of approximately 2.9~\pbinv\ of proton-proton collisions at the LHC at $\sqrt{s} = 7$~TeV. Photons are required to be isolated and to have pseudo-rapidity $|\eta|<2.5$ and a transverse energy $\pt^{\gamma}>21$~\GeV. We measure the reconstruction efficiency of selected photons with the $\Zz\to e^{+}e^{-}$ control sample in data. We estimate the contribution of background from neutral hadron decays by relying on several observables, including the shower shape measured in \ecal, isolation measured in the tracker and calorimeters, and the ratio of the energy measured in the electromagnetic calorimeter (\ecal) to momentum measured in the tracker for converted photons. The resulting fraction of isolated photons and measured yield are presented as a function of photon transverse energy in two pseudo-rapidity regions.