A photon reconstruction algorithm which provides efficiency for photons that enter the FCAL of 99.6\%, and an energy resolution of 4\% for 1 GeV photons, has been implemented in the GlueX analysis framework. The study of single photons, generated from the center of the target in the solid angle covered by the FCAL, revealed a high probability (37\%) for photon conversion before FCAL. The conversion probability shows a strong angular dependence related to the presence of various detector components between the target and FCAL.
The parts of the detector that have a large impact on pre-shower formation were identified. The effect of the TOF and steel plate in front of the FCAL on single photon resolution was found to be insignificant. Taking into account single clusters from photons that converted close to the FCAL face, the overall photon reconstruction efficiency was estimated to be 77%.
