Conference Paper

System test of the ATLAS muon spectrometer in the H8 beam at the CERN SPS

Sch. of Phys. & Astron., Tel Aviv Univ., Israel
DOI: 10.1109/NSSMIC.2004.1462184 Conference: Nuclear Science Symposium Conference Record, 2004 IEEE, Volume: 1
Source: IEEE Xplore


An extensive system test of the ATLAS muon spectrometer has been performed in the H8 beam line at the CERN SPS during the last four years. This spectrometer will use pressurized monitored drift tube (MDT) chambers and cathode strip chambers (CSC) for precision tracking, resistive plate chambers (RPCs) for triggering in the barrel and thin gap chambers (TGCs) for triggering in the end-cap region. The test set-up emulates one projective tower of the barrel (six MDT chambers and six RPCs) and one end-cap octant (six MDT chambers, a CSC and three TGCs), The barrel and end-cap stands have also been equipped with optical alignment systems, aiming at a relative positioning of the precision chambers in each tower to 30-40 micrometers. In addition to the performance of the detectors and the alignment scheme, many other systems aspects of the ATLAS muon spectrometer have been tested and validated with this setup, such as the mechanical detector integration and installation, the detector control system, the data acquisition, high level trigger software and off-line event reconstruction. Measurements with muon energies ranging from 20 to 300 GeV have allowed measuring the trigger and tracking performance of this set-up in a configuration very similar to the final spectrometer. A special bunched muon beam with 25 ns bunch spacing, emulating the LHC bunch structure, has been used to study the timing resolution and bunch identification performance of the trigger chambers. The ATLAS first-level trigger chain has been operated with muon trigger signals for the first time.

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    • "The method has been validated by analyzing data taken with a high momentum muon beam at the CERN SPS [11]. Here an ATLAS BIL chamber was placed on a rotating support in order to have the beam line incident with an angular spread of with respect to the drift tube planes. "
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    ABSTRACT: We present a global time fit to determine the reference time event-by-event in an array of drift cells. The method is applied to the monitored drift tube tracking chambers (MDT) of the muon spectrometer of the ATLAS experiment at the large hadron collider (LHC). During operation with proton-proton collisions, the muon trigger is based on dedicated fast detectors and the readout is clocked at the beam crossing frequency of 40 MHz. A method has been developed for tracking particles through the MDT chambers which works without a precisely timed external trigger. This study was conceived to exploit the MDT tracking capabilities in non standard operation of the ATLAS detector, e.g., during commissioning with cosmic rays when there is no time correlation with the LHC clock frequency. Results obtained using an asynchronous trigger, with a high energy muon beam from the CERN SPS, and with cosmic rays are reported.
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    ABSTRACT: Thin gap chambers (TGCs) are used for the muon trigger system in the forward region of the LHC experiment ATLAS. The TGCs are expected to provide a trigger signal within 25 ns of the bunch spacing. About 3,600 ATLAS TGCs have been produced in Israel, Japan and China. The chambers go through a vigorous quality control program before installation. An extensive system test of the ATLAS muon spectrometer has been performed in the H8 beam line at the CERN SPS during the last few years. Three TGC stations were employed there for triggering muons in the endcap. A relational database was used for storing the conditions of the tests as well as the configuration of the system. This database has provided the detector control system with the information needed for its operation and configuration. The database is used to assist the online operation and maintenance. The same database is storing the non event condition and configuration parameters needed later for the offline and reconstruction software. A larger scale of the database has been produced to support the whole TGC system. It integrates all the production, tests and assembly information. A 1/12th model of the whole TGC system is currently in use for testing the performance of this database in configuring and condition tracking of the system. A mockup of the database was first implemented during the H8 test beams. This paper describes the database structure, its interface to other systems and its operational performance.
    Full-text · Conference Paper · Jul 2005
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    Preview · Conference Paper · Nov 2005
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