The CMS Electromagnetic Calorimeter detector control and monitoring system

The Electromagnetic Calorimeter of the CMS experiment at the LHC is made of 75 848 lead tungstate scintillating crystals and photo-detectors. In order to ensure the design stability and precision, the detectorʹs properties must be continuously monitored. The tests to determine the performance of the detectorʹs crystals, photo detectors and readout electronics are presented in detail. In particular, the identification of different hardware problems that were found is discussed as well as on their development in time.