Abstract :
Atlas is one of the four experiments which will allow the study of proton-proton collision from the LHC (CERN Geneva) at a centre of mass energy of 14 TeV. The identification of electrons arid photons, as well as their energy and timing information will mainly be performed with the electromagnetic calorimeter with liquid Argon as active material. To achieve these tasks the calorimeter system requires a fine granularity resulting in about 200000 readout channels. Other requirements of the readout system are: large dynamic range (from 50 MeV to 3 TeV), low coherent noise, deadtimeless operation at the sampling frequency of the LHC bunch crossings (40 MHz), analog signal sums for the Level1 trigger, "moderate" radiation tolerance. After completion of the construction of the detector, 2003, cryostat has been sealed, cooled and filled with liquid Argon. A fraction of the readout system has been installed on the cryostat. Performance of the readout system, connected for the first time to the cold detector in its final configuration, is covered in this paper. Emphasis is placed on (coherent) noise measurements of critical importance to the calorimeters overall precision.
Keywords :
electron detection; gamma-ray apparatus; liquid ionisation chambers; liquid scintillation detectors; noise; nuclear electronics; particle calorimetry; position sensitive particle detectors; readout electronics; 40 MHz; ATLAS EM barrel calorimeter; LHC bunch crossings; Level1 trigger; analog signal sums; coherent noise; cold detector; cryostat; liquid Argon; proton+proton collision; radiation tolerance; readout channels; readout electronics; Argon; Detectors; Dynamic range; Electrons; Frequency; Large Hadron Collider; Noise level; Readout electronics; Sampling methods; Timing;
