The Data Quality Monitoring of the CMS Experiment: the Tracker Case

The Data Quality Monitoring system in the CMS experiment has been designed for the monitoring of both the online data taking as well as offline data processing, such as reconstruction of data at Tier0. The goal of the online DQM system is to monitor detector performance and identify problems efficiently and with small latency during the data collection. On the other hand the reconstruction or calibration problems can be detected during offline processing using the same tool. The monitoring is performed with histograms which are filled by accessing information from raw and reconstructed data. We shall describe the CMS Data Quality Monitoring system in general with special emphasis on its application to the monitoring of the CMS Silicon Strip Track detector. Experience with the system from the cosmic ray muon data taking, before the installation of the tracking detector in the underground CMS experiment as well as during the global runs after completion of the detector installation, will be reported.