25916750
System test of the ATLAS muon spectrometer in the H8 beam at the CERN SPS
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.
24518202
The thin gap chambers database experience in test beam and preparations for ATLAS
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
54495416
System test of the ATLAS muon spectrometer in the H8 beam at the CERN SPS
We describe a system-test of the ATLAS Muon Spectrometer performed at the H8 beam line of the CERN SPS during 2003. The setup includes one barrel tower made of six Monitored Drift Tube chambers equipped with an alignment system and four Resistive Plate Chambers, and one end-cap octant consisting of six end-cap MDT equipped with an alignment system and one triplet and two doublets of Thin Gap Chambers. Many system aspects of the muon spectrometer have been studied with this setup, from the performance of the precision and trigger chambers to the capability to align the precision chambers at the level of a few tens of micrometers and to operate the muon trigger at the crossing frequency of the LHC.
118170002
Analysis of the tau polarization and its forward - backward asymmetry on the Z0
This thesis describes a new a measurement of the tau lepton polarization and its forward-backward asymmetry at the Z resonance using the OPAL detector. This measurement is based on analyses of the tau->electron, muon and pion (Kaon) decays from a sample of 30663 tau-pair events collected in the polar angle range of Abs(cos(theta)) =(-13.5+/-2.9+/-2.2)% and the tau polarization forward-backward asymmetry to be AFBpol=(-11.0+/-3.5+/-0.5)% where the first error is statistical and the second systematic. Combining these figures with the OPAL and AFBpol measured with the tau->rho channel we get an average tau polarization, =(-14.9+/-1.9+/-1.3)% and for the asymmetry in the polarization, AFBpol=(-8.9+/-2.2+/-0.9)% . These results are consistent with lepton universality. Combining the two results we obtain for the electroweak mixing angle the value sin^2(theta_W)=0.2331+/-0.0023 within the context of the Standard Model, where the error includes both statistical and systematic uncertainties.
125413811
Heavy quarkonium physics with early ATLAS data
30542764
Iterative Track Fitting Using Cluster Classification in Multi Wire Proportional Chamber
This paper addresses the problem of track fitting of a charged particle in a multi wire proportional chamber (MWPC) using cathode readout strips. When a charged particle crosses a MWPC, a positive charge is induced on a cluster of adjacent strips. In the presence of high radiation background, the cluster charge measurements may be contaminated due to background particles, leading to less accurate hit position estimation. The least squares method for track fitting assumes the same position error distribution for all hits and thus loses its optimal properties on contaminated data. For this reason, a new robust algorithm is proposed. The algorithm first uses the known spatial charge distribution caused by a single charged particle over the strips, and classifies the clusters into ldquocleanrdquo and ldquodirtyrdquo clusters. Then, using the classification results, it performs an iterative weighted least squares fitting procedure, updating its optimal weights each iteration. The performance of the suggested algorithm is compared to other track fitting techniques using a simulation of tracks with radiation background. It is shown that the algorithm improves the track fitting performance significantly. A practical implementation of the algorithm is presented for muon track fitting in the cathode strip chamber (CSC) of the ATLAS experiment.
12785495
The Detection of Ionizing Radiation by Plasma Panel Sensors: Cosmic Muons, Ion Beams and Cancer Therapy
The plasma panel sensor is an ionizing photon and particle radiation detector derived from PDP technology with high gain and nanosecond response. Experimental results in detecting cosmic ray muons and beta particles from radioactive sources are described along with applications including high energy and nuclear physics, homeland security and cancer therapeutics