Persistent Back End for the ATLAS Information Service of Trigger and Data Acquisition

ATLAS is the largest of several experiments built along the Large Hadron Collider at CERN, Geneva. Its aim is to measure particle production when protons collide at a very high center of mass energy, thus reproducing the behavior of matter a few instants after the big bang. The detecting techniques used for this purpose are very sophisticated and the amount of digitized data created by the sensing elements requires a very large data acquisition system, based on thousands of interconnected computers. The experiment is successfully taking data since the end of 2008 and the trigger and data acquisition are now in a production stage.The main development eorts are guided towards adding easy to use and intuitive tools to aid experts monitor dierent components or subsystems. P BEAST is an example of such a tool. It facilitates the storage of vast amounts of operational information which is otherwise lost. With this data at hand, long term analysis can be made and issues discovered. The project has reached deployment phase with promising results. This report describes the work done and the results obtained in implementing a persistent system for the ATLAS Online Information Service. The structure carefully follows the evolution of the project. After setting the scene with a brief introduction to CERN and the ATLAS detector, an overview of the project planning and execution is given. Detailed descriptions of requirements, database technology evaluations, design, implementation and testing constitute the bulk of the main body. Achievements and future development plans are discussed in the last section.