Abstract
The ATLAS experiment is designed to study the proton-proton collisions produced at the Large Hadron Collider(LHC) at CERN. Liquid argon sampling calorimeters are used for all electromagnetic calorimetry covering the pseudo-rapidity region up to 3.2, as well as for hadronic calorimetry in the range 1.4–4.9. The electromagnetic calorimeters use lead as passive material and are characterized by an accordion geometry that allows a fast and uniform azimuthal response without any gap. Copper and tungsten were chosen as passive material for the hadronic calorimetry; whereas a classic plate geometry was adopted at large polar angles, an innovative one based on cylindrical electrodes with thin argon gaps was designed for the coverage at low angles, where the particle flow is higher. All detectors are housed in three cryostats kept at about 88 K. After installation in 2004–2006, the calorimeters were extensively commissioned over the three years period prior to first collisions in 2009, using cosmic rays and single LHC beams. Since then, around 9 fb−1 (as of June, 2012) of data have been collected at a center of mass energy of 7 and 8 TeV. During all these stages, the calorimeter and its electronics have been operating almost optimally, with performances very close to the specifications.
Highlights
The ATLAS [1] Liquid Argon (LAr) calorimeters [2] have been installed and fully operational since the cosmic-ray data-taking in 2006
With the first LHC collisions coming in 2009, the Liquid Argon calorimeters have collected over 9 fb−1 of proton-proton collision data as of June 4th, 2012 [3]
Signal Readout Ionization from charged particles crossing the liquid argon gap in the calorimeters drifts through a high electric field generated by the LAr high-voltage system in between the absorber plates and readout electrodes
Summary
The ATLAS [1] Liquid Argon (LAr) calorimeters [2] have been installed and fully operational since the cosmic-ray data-taking in 2006. 1. Introduction The ATLAS [1] Liquid Argon (LAr) calorimeters [2] have been installed and fully operational since the cosmic-ray data-taking in 2006. With the first LHC collisions coming in 2009, the Liquid Argon calorimeters have collected over 9 fb−1 of proton-proton collision data as of June 4th, 2012 (see figures 1,2) [3].
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