sPHENIX is a new experiment under construction for the Relativistic Heavy Ion Collider at Brookhaven National Laboratory which will study the quark-gluon plasma to further the understanding of QCD matter and interactions. A prototype of the sPHENIX electromagnetic calorimeter (EMCal) was tested at the Fermilab Test Beam Facility in Spring 2018 as experiment T-1044. The EMCal prototype corresponds to a solid angle of $ Delta eta times Delta phi = 0.2 times 0.2$ centered at pseudo-rapidity $eta = 1$. The prototype consists of scintillating fibers embedded in a mix of tungsten powder and epoxy. The fibers project back approximately to the center of the sPHENIX detector, giving 2D projectivity. The energy response of the EMCal prototype was studied as a function of position and input energy. The energy resolution of the EMCal prototype was obtained after applying a position dependent energy correction and a beam profile correction. Two separate position dependent corrections were considered. The EMCal energy resolution was found to be $sigma(E)/langle Erangle = 3.5(0.1) oplus 13.3(0.2)/sqrt{E}$ based on the hodoscope position dependent correction, and $sigma(E)/langle Erangle = 3.0(0.1) oplus 15.4(0.3)/sqrt{E}$ based on the cluster position dependent correction. These energy resolution results meet the requirements of the sPHENIX physics program.
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