&\
Type A + Stat. & 1.0$\%-$1.9$\%$ & 2.6$\%-$4.4$\%$ & 4$\%-$6$\%$ & 6$\%-$13$\%$\
Type B & 10.5$\%-$10.7$\%$ & 14.3$\%-$14.4$\%$ & 13.7$\%-$14.1$\%$ & 14.4$\%-$14.7$\%$\
Type C & 12$\%-$23$\%$ & 12$\%-$23$\%$ & 12$\%-$23$\%$ & 12$\%-$23$\%$\
\
& &\
Type A + Stat. & 4$\%-$6$\%$ & 4$\%-$12$\%$ & &\
Type B & 10.9$\%-$11.4$\%$ & 14.7$\%-$15.1$\%$ & &\
Type C & $-$ & $-$ & &\

![Example of an invariant mass plot ($4.5<{\mbox{$p_T$}\xspace}<5.0$). (a) The foreground (photon pairs from the same event) is shown as points, the shaded area is the scaled mixed event background. Insert (b) shows the peak area after mixed event subtraction; the Gaussian fit to the peak and the first order polynomial fit to the residual background are also shown. Insert (c) shows the $\eta$ peak area with the Gaussian fit and second order polynomial for the residual background. []{data-label="fig:FIG0_InvMass_Example"}](FIG1_InvMass_rev3_1cp.pdf){width="1.0\linewidth"}

One of the main sources of systematic uncertainties is the absolute energy calibration of the EMCal. The uncertainty on the absolute scale was estimated to be $1\%$. Due to the steeply falling (power-law) spectrum it corresponds to $\approx2$-$9\%$ uncertainty for the measured yields of $\pi^0$ and $\eta$ mesons, which gradually increases from low to high momentum. At high the measured 