The ATLAS hadronic tile calorimeter: from construction toward physics

The Tile Calorimeter, which constitutes the central section of the ATLAS hadronic calorimeter, is a non-compensating sampling device made of iron and scintillating tiles. The construction phase of the calorimeter is nearly complete, and most of the effort now is directed toward the final assembly and commissioning in the underground experimental hall. The layout of the calorimeter and the tasks carried out during construction are described, first with a brief reminder of the requirements that drove the calorimeter design. During the last few years a comprehensive test-beam program has been followed in order to establish the calorimeter electromagnetic energy scale, to study its uniformity, and to compare real data to Monte Carlo simulation. The test-beam setup and first results from the data are described. During the test-beam period in 2004, lasting several months, data have been acquired with a complete slice of the central ATLAS calorimeter. The data collected in the test-beam are crucial in order to study algorithms for hadronic energy reconstruction using single particles. The generalization of these algorithms to reconstruct jet energies will be the starting point for numerous physics studies in which jets play a leading role. The results obtained in applying these algorithms to simulated di-jet events are given in the last section of the note.