A Monte-Carlo simulation program of the response of the Endcap Electromagnetic Calorimeter (EEMC) and Shower Maximum Detector (SMD) was developed to determine the ability, of the detectors, to provide y/n° discrimination and calculate the effects crosstalk between readout channels from multianode photomultiplier tubes (MAPMT). The importance of this discrimination process is to allow a better measure of the direct-photon asymmetries, which are then used to calculate the gluon contribution to the proton spin structure. These measurements arise from polarized-proton collisions provided by the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory and are detected using the Solenoidal Tracker at RHIC (STAR), which includes the EEMC and SMD. In order to obtain accurate asymmetry measurements, the photons resulting from 7c° decay must be identified through pion-mass reconstruction to avoid confusing them as direct photons. This Monte-Carlo simulation and reconstruction algorithm successfully identified 60% of the pions from single-pion events and 40% of the pions from two-pion events. The effects of MAPMT crosstalk, as determined by the Monte Carlo, were less than 2% on n° identification, and therefore were determined to be insignificant. / Department of Physics and Astronomy