Data

Monte Carlo

The above are the same four plots for data and monte carlo.  They are (clockwise from top left) the single-photon eta distribution, phi distribution, eta vs. phi distributions, and Pt distribution.  All single photons (THits) from good runs that have SMD information are plotted.  There are some glaring inconsistencies, which leads me to believe that I haven't modeled the detector correctly in MC.  Most notably, there are far more hits in the 0<phi<1 range in data than in simulation.  Furthermore, the real data is weighted more towards positive eta, whereas in MC the eta distribution is somewhat flat.  These differences show up in the eta-phi plots.  Finally, in the data Pt spectrum there is a second peak around 5.5 GeV which is not reflected in data.  My initial thought is that these hits are actually Etas; that the detector failed to resolve the two daughter photons and reconstructed just one at a higher Pt.  I'm not sure why this doesn't appear in MC.  I'm going to have to go back and try to better model the detector for my next pass at the simulation.