Monitoring and Data Quality Assessment for the ATLAS Liquid Argon Calorimeter at the LHC

Abstract

The ATLAS detector at the Large Hadron Collider, in full operation since fall 2009, is expected to collect an unprecedented wealth of data at a completely new energy scale. In particular, its Liquid Argon (LAr) electromagnetic and hadronic calorimeters will play an essential role in measuring final states with electrons and photons and in contributing to the measurement of jets and missing transverse energy. The ATLAS LAr calorimeter is a system of three sampling calorimeters with LAr as sensitive medium. It is composed by 182,468 readout channels and covers a pseudorapidity ( η = − ln ( θ / 2 ) ) region up to 4.9. Efficient monitoring will be crucial from the earliest data taking onward and at multiple levels of the electronic readout and triggering systems. Detection of serious data integrity issues along the readout chain during data taking will be essential so that quick actions can be taken. Moreover, by providing essential information about the performance of each subdetector, the quality of the data collected (hot or dead channels, calibration problems, timing problems...) and their impact on physics measurables, the monitoring will be critical in guaranteeing that data are ready for physics analysis in due time. Software tools and general data quality policy, developed and tuned since 2006 and first ATLAS cosmic runs, are discussed. A special emphasis on the monitoring procedures during the first LHC collisions run will be given. The roadmap to achieve a fully automated system will be finally mentioned.