Left: Shower shape parameter \shshlo\ versus neutral cluster \pt. The band limited by the black dashed lines indicates the area populated by single photons and defines the photon selection cuts (narrow clusters) used in the analysis. Right: Distributions of the shower shape parameterfor different types of clusters produced by single photons (red bullets) or overlapped photons from \piz\ decays (black bullets) for different cluster energies from PYTHIA 6 $\gamma$-jet and jet-jet simulations with GEANT3 tuned for cross-talk emulation. A line at $\shshlo=0.3$ represents the cut used to select narrow clusters at $\ptg > 18$\,\GeVc. All distributions are normalised to an integral of 1. In the left plot each \pt\ bin is separately normalised to 1.