Showing papers by "Laurent Chevalier published in 2007"

A muon identification and combined reconstruction procedure for the ATLAS detector at the LHC using the (MUONBOY, STACO, MuTag) reconstruction packages

Abstract: A robust muon identification and high momentum measurement accuracy is crucial to fully exploit the physics potential that will be accessible with the ATLAS experiment at the LHC at CERN. In this paper an overview of the muon reconstruction software is given and performance results from detailed Geant4-based simulations are presented.

Impacts of misalignment in the ATLAS Muon Spectrometer on the measured Z-Boson resonance

Abstract: The study of the Z Boson and its decay into two muons at ATLAS provides several interesting aspects. Since the mass and the width of the Z-Boson is known to a very high precision from LEP experiments, Z decays can be used for precision tests of the detector, in particular for alignment issues. Various effects of misalignments in the ATLAS Muon Spectrometer on the reconstructed Z-Boson resonance are discussed. Moreover, the impacts on the precision of muon momentum reconstruction were studied.

Combined test beam results on the alignment of Muon chambers and Muon reconstruction in the 2004 ATLAS H8 setup

Abstract: ATLAS detector is designed to exploit the full discovery potential of the LHC proton–proton collider at CERN, at an energy of 14 TeV. The detector, which is optimized for operating at high luminosity, features an inner tracker, Electromagnetic and Hadronic calorimeters and a Muon Spectrometer. The ATLAS Muon Spectrometer is composed of tracking and trigger detectors, which span a total area of 5500 m 2 . The design of the spectrometer provides very good momentum resolution that varies between 2% and 10% for momentum ranging from 5 GeV to 1 TeV. To achieve this resolution, the 1200 individual tracking chambers composed of Monitored Drift Tubes (MDT) are constructed with mechanical precision better than 20 μm, while the position and deformation of individual chambers will be monitored with an optical alignment system to be better than 40 μm during data taking. In 2004, a combined systems test of a ϕ sector of the following ATLAS sub-detectors: the Inner Detector, the Liquid Argon Calorimeter, the Tile Hadronic Calorimeter and the Muon Spectrometer, was performed in the H8 beam line at the CERN SPS. Results obtained on the alignment of the MDT chambers in the Muon Spectrometer setup, the performance of the MDT chambers and the reconstruction of Muon tracks using the combined information from both the Inner Detector and the Muon Spectrometer are presented here.

Impacts of misalignment effects on the Muon Spectrometer Performance

Abstract: The ATLAS detector, currently being installed at CERN, is designed to exploit the full potential of the LHC. Starting in 2008, it will identify and provide highly accurate energy and momentum measurements of particles emerging from the LHC proton-proton collisions with a centre-of-mass energy at 14 TeV. High-momentum muons will be detected in a highresolution Muon Spectrometer with standalone triggering and momentum measurement. Muons with an energy of more than a few GeV penetrate the calorimeter and reach the Muon Spectrometer, which consists of drift-tubes chambers. The correct alignment of the ATLAS Muon Spectrometer is crucial to ensure its design performance. This note documents the attempt of using various misaligned Muon Spectrometer layouts to study their impacts Muon Spectrometer performance. These impact on have been studied with a 50GeV muon sample and a Z → μμ sample. The samples have been simulated with an ideal Muon Spectrometer layout, while during reconstruction a misaligned layout has been assumend. An average uncertainty of roughly 1 mm in the chamber position deteriorates the momentum resolution from 4% to 9% for muons with a momentum of 50GeV. 1)present affiliation is Univ. Illinois at Urbana-Champaign, Department of Physics, USA 2)Corresponding Author