CERN Accelerating science

Internal Note and Article
Report number	ATL-MUON-PUB-2008-003 ; ATL-COM-MUON-2008-005
Title	The Optical Alignment System of the ATLAS Muon Spectrometer Endcaps
Author(s)	Aefsky, S (Brandeis U.) ; Amelung, C (Brandeis U. ; CERN) ; Bensinger, J (Brandeis U.) ; Blocker, C (Brandeis U.) ; Dushkin, A (Brandeis U.) ; Gardner, M (Brandeis U.) ; Hashemi, K (Brandeis U.) ; Henry, E (Harvard U.) ; Kaplan, B (Brandeis U.) ; Ketchum, M (Brandeis U.) ; Keselman, P (Brandeis U.) ; Landgraf, U (Freiburg U.) ; Ostapchuk, A (Munich, Max Planck Inst.) ; Rothberg, J E (Washington U., Seattle) ; Schricker, A (Brandeis U. ; CERN) ; Skvorodnev, N (Brandeis U.) ; Wellenstein, H (Brandeis U.)
Publication	2008
Imprint	19 Feb 2008
Number of pages	49
In:	JINST 3 (2008) P11005
DOI	10.1088/1748-0221/3/11/P11005
Subject category	Detectors and Experimental Techniques
Accelerator/Facility, Experiment	CERN LHC ; ATLAS CERN SPS
Test beam	H8
Free keywords	muon spectrometer ; alignment system ; optical sensor
Abstract	The muon spectrometer of the ATLAS detector at the Large Hadron Collider (LHC) at CERN consists of over a thousand muon precision chambers, arranged in three concentrical cylinders in the barrel region, and in four wheels in each of the two endcaps. The endcap wheels are located between 7m and 22m from the interaction point, and have diameters between 13m and 24m. Muon chambers are equipped with a complex on-line optical alignment system to monitor their positions and deformations during ATLAS data-taking. We describe the layout of the endcap part of the alignment system and the design and calibration of the optical sensors, as well as the various software components. About 1% of the system has been subjected to performance tests in the H8 beam line at CERN, and results of these tests are discussed. The installation and commissioning of the full system in the ATLAS cavern is well underway, and results from approximately half of the system indicate that we will reach the ambitious goal of a 40mu alignment accuracy, required for reconstructing final-state muons at the highest expected energies.
Copyright/License	Publication: (License: CC-BY-3.0)

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Email contact: christoph.amelung@cern.ch