Development of a framework to monitor the performances and the data quality of the ATLAS RPC trigger chambers using the Calibration Stream data

The CERN1 laboratory, near Geneva, hosts the Large Hadron Collider (LHC), the highest energy hadron-hadron accelerator-collider in the world. It operates since 2009, withacontinuousincreaseofthecenterofmassenergywhich, in2012, reachedthehighest value of 8TeV. During this period it delivered an integrated luminosity of approximately 28fb−1. The ATLAS2 experiment, installed in one of the experimental hole along the LHC tunnel, is able both to investigate the Standard Model physics and to search for evidence of new signals beyond it. On the fourth of July 2012 the ATLAS and CMS3 collaborations announced together the discovery of a new boson[4]. The subsequent analysis confirmed the Standard Model Higgs nature of the new particle. A technical shutdown, to upgrade the LHC system, is currently underway. At the restart, expected in 2015, the energy in the center of mass should reach 13 TeV and the instantaneous luminosity will increase up to 1034cm−2s−1. This thesis is organized as follows: An introduction to the LHC system and the ATLAS experiment can be found in chapters 1 and 2. Special attention is dedicated to the ATLAS Muon Spectrometer, which is used to trigger, track the muon particles and measure their pT . The trigger system in the barrel of the ATLAS Muon Spectrometer consists of Resistive Plate Chambers (RPC). A detailed description of these gaseous detectors is given in chapter 3. The ATLAS experiment, and the RPC chambers, are expected to operate at least for the next 10-15 years of data taking. For this reason a continuous monitoring on the status and the performances of the RPC chambers is required. This work focused on the development of a complete software environment consisting of physics analysis, task manager routines and work-flow procedure, to enable simple and reliable monitoring of the RPC system using Grid computing resources. The work presented in this thesis uses the high statistics data stream,calledCalibration Stream, for the analysis; although increasing computing capacity is required to perform such as analysis, it permits the production, per run, of RPC performances results, such as efficiency tomography plots, which are not possible when using other analysis chains. Chapters 4 and 5 describe the author’s work in the development of the RPC physics analysis for the RPC monitoring system and its subsequent integration into the Local Calibration Data Splitter. Finally chapter 6 contains a typical “use case” illustrating the users work procedure and associated analysis results.