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Abstract: The ATLAS Muon Spectrometer is designed to measure the momentum of muons with a resolution of dp/p=3% at 100GeV and 10% at 1TeV. For this task, the spectrometer employs 355,000 Monitored Drift Tubes (MDTs) arrayed in 1200 chambers. Calibration (RT) functions convert drift time measurements into tube-centered impact parameters for track segment reconstruction. RT functions depend on MDT environmental parameters and so must be appropriately calibrated for local chamber conditions. We report on the creation and application of a gas monitor system based calibration program for muon track reconstruction in the LHC startup phase. [Copyright &y& Elsevier]

The Atlas muon spectrometer relies on Monitored Drift Tubes (MDTs) for track reconstruction in most regions. Expected count rates due to photons reach up to 1500 Hz/cm for the innermost MDTs. For a gas gain of 2middot104 this corresponds to an overall accumulated charge of up to 0.6 C/cm which the MDTs must be able to withstand in 10 years of LHC operation without a degradation in their performance. With the main MDT parameters and the design frozen and chamber production well under way the focus of present aging studies is on testing final Atlas chambers instead of using small, dedicated setups under very well controlled conditions as in the past. This paper summarizes the results of such a study performed at the CERN Gamma Irradiation Facility GIF, that aims to emulate LHC background conditions. One of the main goals was to evaluate the principle of gas recirculation and a prototype of the Atlas circulation system [ABSTRACT FROM PUBLISHER]

A cosmic ray measurement facility has been set up at Ludwig-Maximilians-University Munich (LMU) and is used at present to commission and calibrate Monitored Drift Tube (MDT) chambers for the muon spectrometer of the ATLAS experiment. Each of these chambers-produced in collaboration with the Max-Planck-Institut fuumlr Physik and the Joint Institute for Nuclear Research in Dubna-consists of 432 drift tubes with a diameter of 3 cm, which are arranged in 2times3 layers, and measures 3.8 mtimes2.2 mtimes0.5 m. At the LMU site, the MDT chambers are completed, equipped with their final front-end electronics and taken into operation for the first time. The gas leak rate of the chamber is determined and its high voltage stability is tested. The response of all drift tubes and its homogeneity across the chamber is measured in the Cosmic Ray Facility. Two MDT chambers which were precisely mapped with an X-Ray tomograph provide reference tracking for the enclosed third chamber which is to be calibrated. The sense wire positions are determined from a comparison of the drift time measurements with the reference tracks. The geometry of the tested chamber-the grid constants of the drift tubes in a layer, the distances and tilt angles of the layers-can then be derived from these positions. Alignment systems are used to monitor chamber movements at the micrometer level. In the ongoing series commissioning, a rate of one chamber per week has been achieved. The parameters describing the geometry of the MDT chambers are determined with a precision in the 10 mum range. The measurements with cosmic muons complement the chamber surveys performed during construction and will provide an important input for the calibration of the entire ATLAS muon spectrometer [ABSTRACT FROM PUBLISHER]

Abstract: The LHCb experiment is a single-arm spectrometer, designed to study CP violation in B-decays at the Large Hadron Collider (LHC). It is crucial to accurately and efficiently track the charged decay products, in the high-density particle environment of the LHC. For this, the Outer Tracker has been constructed, consisting of straw tubes, distributed over a sensitive area of 12 double layers of 6×5m2 each. The detector is foreseen to operate up to 100kHz/cm per straw in the region closest to the beam. The task of the Front-End Electronics is to provide the precise (0.5ns) drift-time measurement, at an average occupancy of 5% and at a 1MHz trigger rate. The tracking procedure requires high-efficiency (low thresholds), while at the same time putting stringent limits on the noise level. The modular detector structure reflects on the FE electronics: 128 channels are read out by one FE “Box”. The mass production and installation of 450 FE-Boxes is completed. Quality checks have been performed in several stages, at the level of individual boards and at the global level with dedicated test systems mimicking the real detector and capable of simulating all the readout functionalities. At the time of the conference, all FE electronics has been commissioned in situ with test-pulses, cosmic rays and the with first beam events from LHC. No dead channels and very few noisy channels have been found. An upgrade is currently under study, aiming at digitizing and reading out events at each beam-crossing. [ABSTRACT FROM AUTHOR]