18367350
Vertex reconstructing neural network at the ZEUS central tracking detector
An unconventional solution for finding the location of event creation is presented. It is based on two feed-forward neural networks with fixed architecture, whose parameters are chosen so as to reach a high accuracy. The interaction point location is a parameter that can be used to select events of interest from the very high rate of events created at the current experiments in High Energy Physics. The system suggested here is tested on simulated data sets of the ZEUS Central Tracking Detector, and is shown to perform better than conventional algorithms.
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.
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.
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.
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
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