Data quality monitoring of the CMS tracker

Abstract

The Physics and Data Quality Monitoring (DQM) framework aims at providing a homogeneous monitoring environment across various applications related to data taking at the CMS experiment. It has been designed to be used during online data taking as well as during offline reconstruction. The goal of the online system is to monitor detector performance and identify problems very efficiently during data collection so that proper actions can be taken. 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 with information from raw and reconstructed data. All histograms can then be displayed both in the central CMS DQM graphical user interface (GUI), as well as in Tracker specific expert GUIs and socalled Tracker Maps. Applications are in place to further process the information from these basic histograms by summarizing them in overview plots, by evaluating them with automated statistical tests, and by extracting their main qualities and filling them into trend plots, which monitor the behaviour of the detector over time. We describe the CMS Data Quality Monitoring system of the Silicon Strip and Pixel Tracker of CMS, as well as first experience from the cosmic ray data and collision data taking periods.