A. Dotti

Strategies and Tools for ATLAS Online Monitoring

ATLAS is one of the four experiments under construction along the Large Hadron Collider (LHC) ring at CERN. The LHC will produce interactions at a center-of-mass energy equal to radics = 14 TeV with a frequency of 40 MHz. The detector consists of more than 140 million electronic channels. The challenging experimental environment and the extreme detector complexity impose the necessity of a common, scalable, distributed monitoring framework, which can be tuned for optimal use by different ATLAS sub-detectors at the various levels of the ATLAS data flow. This paper presents the architecture of this monitoring software framework and describes its current implementation, which has already been used at the ATLAS beam test activity in 2004. Preliminary performance results, obtained on a computer cluster consisting of 700 nodes, will also be presented, showing that the performance of the current implementation is within the range of the final ATLAS requirements.

GNAM: a low-level monitoring program for the ATLAS experiment

During the last years many test-beam sessions were carried out on each ATLAS subdetector in order to assess the performances in standalone mode. During these tests, different monitoring programs were developed to ease the setup of correct running conditions and the assessment of data quality. The experience has converged into a common effort to develop a monitoring program, which aims to be exploitable by various subdetector groups. The requirements which drove the design of the program as well as its architecture are discussed in this paper. Characteristic features of the application are a modular software based on a Finite State Machine core to implement the synchronization with the data acquisition system and exploiting the ROOT Tree as transient data store. The first version of this monitoring program was used for the 2004 ATLAS Combined Test Beam.