Raw distribution of the invariant mass of cluster pairs in \gls{EMCal} (left) and \gls{DCal} (right) for one run of 2018 data taking obtained during the \gls{QA} process. The red line corresponds to a fit to the invariant mass distribution with a Gaussian function for the \piz\ signal and a second-order polynomial for the background. The fit parameters are used to monitor the performance of the reconstruction and of the detectors. In the displayed run, 819535 events were collected.