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Abstract: The muon tomography technique, based on the Multiple Coulomb Scattering of cosmic ray muons, has been proposed recently as a tool to perform non-destructive assays of large-volume objects without any radiation hazard. In this paper we discuss experimental results obtained with a scanning system prototype, assembled using two large-area CMS Muon Barrel drift chambers. The capability of the apparatus to produce 3D images of objects and to classify them according to their density is presented. We show that the absorption of low-momentum muons in the scanned objects produces an underestimate of their scattering density, making the discrimination of materials heavier than lead more difficult. [Copyright &y& Elsevier]

Abstract: Precision measurements at the International Linear Collider on physics channels of crucial interest are demanding for resolution of the order of up to momenta as high as . A light weight He-based drift chamber with full stereo wires is proposed together with a cluster counting technique, performing potentially better than state-of-the-art TPCs. Detailed studies on the implementation of cluster counting and realization of custom front-end electronics is in advancement. Experimental tools for space resolution measurements with precision is being set up, in preparation of an extensive program of cosmic rays and beam tests. [Copyright &y& Elsevier]

The design of the pixel chamber is described, and the results of investigation of its characteristics are presented. The spatial resolution averaged over a cell of the pixel chamber is 0.9 mm at a beam intensity of up to 106 s−1 and becomes equal to 1.1 mm at an intensity of 5 × 106 s−1. The chamber efficiency is ∼90% at a beam intensity of 10−1 and decreases to 75% at 5 × 106 s−1. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: A brief evolution of about 30 years of tracking with gas drift chambers will be presented, emphasizing the progress made in this field thanks to Abe Seiden, whom we are honoring today. [Copyright &y& Elsevier]

Abstract: I describe aspects of the design, performance, and achievements of the Mark II drift chamber, and some design considerations for tracking at the Superconducting Supercollider (SSC). The emphasis is mainly on contributions made by Abe Seiden and his group at the Santa Cruz Institute for Particle Physics, on the occasion of his 60th birthday. [Copyright &y& Elsevier]

Abstract: The ‘EPECUR’ experimental setup is under construction at beam line 322 of the ITEP proton synchrotron. The experiment requires several large area drift chambers to provide reasonable acceptance and fine-pitch proportional chambers for beam particle tracking. The total number of electronic channels is about 7000. A new compact and cost effective readout system for these gaseous detectors was designed, prototyped and tested in the last two years. It is based on modern technologies in analog and digital electronics and data transfer protocols. This paper presents the functional description of the whole DAQ system, including test results as an illustration of its performance. [Copyright &y& Elsevier]

A construction and functions of the bench for checking the electronic equipment for recording signals from drift chambers, which is composed of 1500 channels for measuring nanosecond time intervals, is described. The special attention is paid to realizing the software-based functions of data control, observation, and monitoring. [ABSTRACT FROM AUTHOR]

Abstract: A new multiwire proportional chamber (MWPC) was designed and constructed for precision studies of neutron decay angular correlations. Its design has several novel features, including the use of low pressure neopentane as the MWPC gas and an entrance window made of thin Mylar sheet reinforced with Kevlar fibers. In the initial off-line performance tests, the gas gain of neopentane and the position resolution were studied. [Copyright &y& Elsevier]

Abstract: A full-length prototype of the BESIII drift chamber together with its readout electronics was built and a beam test was performed. Two different methods, namely “single-threshold method” and “double-threshold method” for timing measurement, were studied. Test results show that the BESIII drift chamber and its readout electronics can reach their design specifications. The “double-threshold method” results in a better timing accuracy and noise suppression capabilities as compared with the “single-threshold method”. [Copyright &y& Elsevier]

Abstract: The present GAMMA10 experiment suggests that the ions trapped in the thermal barrier cell escape from there radially, although the mechanism of the radial loss of ions is unknown. But, a numerical calculation by the drift equation suggests that the existence of non-axisymmetric potential is one of the leading causes of the radial loss of ions in the axisymmetric end-mirror cells. Because it is difficult to analyze the orbits of ions in the actual magnetic field in GAMMA10, the qualitative approach by mapping equation is adopted. The mapping equation obtained is investigated for its properties by comparison with the standard mapping. In the result, it is confirmed that the existence of the small perturbations with high mode numbers in the electrostatic potential affects the orbits of ions greatly. [Copyright &y& Elsevier]

Thin gap chamber (TGC) is a very thin multiwire proportional chamber of only a few millimeters. It has a quick response (about 20 ns), and its production costs are relatively low. TGCs have been used as large area detectors in high energy physics such as Large Electron-Positron collider (LEP) and will be used in the Large Hadron collider (LHC) experiment. However, the characteristics of TGCs under neutrons are not yet clearly understood. As the energy deposits of several MeV neutrons in TGCs are large, the possible effect of these deposits on the operation of the detector is a concern. We studied TGC performance in relation to efficiency, charge distribution, and operation stability using several gas mixtures (CO2/n-pentane and CF4/n-pentane) with 2.5 and 14 MeV neutron sources at Fusion Neutronics Source (FNS) in Japan Atomic Energy Agency. Operation stability using a CF4 based gas was more than 100 times greater than with CO2 based gas, while the minimum ionizing particle signal gain was almost the same. The detection efficiencies were around 0.1% (14 MeV) and 0.02% (2.5 MeV). These results are consistent with our simulation studies. [ABSTRACT FROM AUTHOR]

Abstract: The CDF Run II tracking and vertexing detectors consist of a large cylindrical drift chamber (COT) and a combination of three silicon detector components. An unexpected wire aging problem was found in the COT in late 2003 which resulted in substantial gain drop in the inner layers. Hydrocarbon growth was found to be the cause of aging, and the performance of the COT was fully recovered by adding 100ppm oxygen to the standard chamber gas. The silicon detector contains eight layers of double-sided silicon microstrip sensors. Our experiences with commissioning and operating this complex device and the performance of the detector are reviewed. As the luminosity delivered by the Tevatron has increased, measurable effects of radiation damage have been observed. Recent studies of the change of full depletion voltage versus integrated luminosities are presented. [Copyright &y& Elsevier]

Abstract: We present measurements of ionization energy deposit in (15%) and of transition radiation in an irregular radiator. The measurements are performed with prototypes of the ALICE Transition Radiation Detector (TRD) with a beam of electrons and pions of 1–. We also present resulting electron–pion separation performances for the prototype chambers as well as for final, full-size TRD chambers. [Copyright &y& Elsevier]

In modern high energy and nuclear physics experiments, the complexity of gas detectors and their operation in areas not accessible during the data-taking periods require dedicated gas and safety systems running automatically and controlled by PC. In the FINUDA experiment, to control the gas systems of the drift and He chambers and to monitor the relevant parameters such as helium atmosphere purity and gas mixture composition which affect the experimental performances, three programs were written in National Instruments (NI) LabVIEW and Datalogging and Supervisory Control environment. Two safety systems work continuously to check the hydrocarbon leakages, inside and outside the He Chamber: pre-alarm and alarm signals feed a NI Field Point, where a real time program sends, via Ethernet, the FINUDA safety status to all detectors. [ABSTRACT FROM AUTHOR]

In the ATLAS muon spectrometer, large drift-tube chambers are used for precision tracking. The chambers will be operated at a high neutron and γ background resulting in count rates of up to 500 Hz cm-2 corresponding to 300 kHz per tube. The spatial resolution of the drift tubes is degraded from 82 µm without background to 108 µm at 500 Hz cm-2 background count rate. Due to afterpulsing in the Ar/CO2 gas mixture used in the drift tubes, ionizing radiation causes more than one hit in a tube within the maximum drift time of about 800 ns which is expected for magnetic field strengths around 1.2 T. In order to limit the count rate, the drift tubes are read out with an artificial dead time of 790 ns which causes an efficiency loss of 23% at a rate of 300 kHz per tube. The space-to-drift-time relationship of the tubes varies with background rate, temperature, and magnetic field strength. The mean magnetic field strength in a muon chamber is 0.4 T on the average, but may vary by up to 0.4 T within a chamber. The space-to-drift-time relationship must therefore be determined in short time intervals with an accuracy better than 20 µm using muon tracks and applying corrections for measured magnetic field variations. [ABSTRACT FROM AUTHOR]

In order to ensure that the resistive plate chambers used in the ATLAS experiment will not show, during their operation, any abnormal aging effect which could degrade their performances, an aging test is being performed at X5-GIF, CERN's gamma irradiation facility. In this paper, the latest results are presented, together with an example of successful damage recovery technique. [ABSTRACT FROM AUTHOR]

We have developed and successfully tested a prototype of a new high position resolution hybrid X-ray detector. It contains a thin-wall lead glass capillary plate converter of X-rays combined with a microgap parallel-plate avalanche chamber operating in various gas mixtures at 1 atm. The operation of these converters was studied in a wide range of X-ray energies (from 6 to 60 keV) at incident angles varying from 0-90°. The detection efficiency, depending on the geometry, photon's energy, incident angle and the mode of operation was between 5-30% in single step mode and up to 50% in a multi-layered combination. Depending on the capillary's geometry, the position resolution achieved was between 50-250 µm in digital form and was practically independent of the photon's energy or gas mixture. The usual lead glass capillary plates operated without noticeable charging up effects at counting rates of 50 Hz/mm² and hydrogen treated capillaries—up to 105 Hz/mm². The developed detector has several important potential advantages over the exciting X-ray detectors and may open new possibilities for medical imaging, for example in mammography, portal imaging, radiography (including security devices), as well as many other applications. [ABSTRACT FROM AUTHOR]

Multiwire proportional chambers (MWPCs) are widely used in many different disciplines. The quality of the results depends on many factors such as gas gain, detector count rate, detection efficiency, spatial and energy resolution, and uniformity. We report here on a detailed study on how to optimize all these features, in particular regarding the use of MWPC at synchrotron radiation sources. Detector behavior has been analyzed in relation to geometry of the wire planes; electric field; frames design and window geometry; and gas parameters. From this study, general optimization criteria were obtained. The results of this study have been applied to produce a new design for a detector required to perform time-resolved X-ray diffraction/scattering experiments in the submillisecond time scale with a spatial resolution of 0.03 cm. In addition, we report on the outcome of simulations aiming at understanding the influence of manufacturing defects as well as gas quality. [ABSTRACT FROM AUTHOR]

Abstract: A prototype of the BESIII drift chamber was tested with gas mixture in a 1T magnetic field at the -2 beam line of KEK 12GeV PS. The drift distance–time relationship was extracted for various conditions. The performance of the chamber, such as the spatial resolution, the resolution and the cell efficiency, was studied in detail. The was measured as a function of to calculate the particle separation power. Based on the test results, the operating voltage of the BESIII drift chamber is optimized to be 2200V, resulting in a spatial resolution better than , a cell efficiency over 98%, a resolution better than 5% and the separation at a momentum exceeding . These results confirm the validation of the physics design of the BESIII drift chamber. [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]

We report the electron and hole charge transport properties of semi insulating CdTe:Cl grown by the Travelling Heater Method (THM). An alpha-particle Time of Flight (TOF) method was used to measure electron and hole drift mobility, with room temperature values of 880 cm2 /Vs for electrons and 90 cm2/Vs for holes. The variation in mobility was also investigated as a function of temperature, with electron and hole mobilities at 190 K of 1150 cm2 /Vs and 20 cm2/Vs respectively. Using a Hecht analysis the electron and hole mobility-lifetime products were also measured over the same temperature range, with values at room temperature of 8times10-4 cm2/V and 7times10-5 cm 2/V respectively. Time-resolved ion beam induced charge (IBIC) imaging was used to produce micrometer resolution maps of electron drift mobility and signal amplitude, which showed excellent spatial uniformity [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]

The Central Outer Tracker (COT) is a large axial drift chamber in the Collider Detector at Fermilab operating with a gas mixture that is 50/50 argon/ethane with an admixture of 1.7% isopropanol. In its first two years of operation the COT showed unexpected aging with the worst parts of the chamber experiencing a gain loss of ~50% for an accumulated charge of ~35 mC/cm. By monitoring the pulse height of hits on good tracks, it was possible to determine the gain as a function of time and location in the chamber. In addition, the currents of the high voltage supplies gave another monitor of chamber gain and its dependence on the charge deposition rate. The aging was worse on the exhaust end of the chamber consistent with polymer buildup as the gas flows through the chamber. The distribution in azimuth suggests that aging is enhanced at lower temperatures, but other factors such as gas flow patterns may be involved. Elemental and molecular analysis of the sense wires found a coating that is mostly carbon and hydrogen with a small amount of oxygen; no silicon or other contaminants were identified. High resolution electron microscope pictures of the wire surface show that the coating is smooth with small sub-micron nodules. In the course of working with the chamber gas system, we discovered a small amount of O 2 is enough to reverse the aging. Operating the chamber with ~100 ppm of O2 reversed almost two years of gain loss in less than 10 days while accumulating les2 mC/cm [ABSTRACT FROM PUBLISHER]

In order to explore new physics in B-meson decays we plan to upgrade the KEK B-factory to a luminosity of 5 × 1035 cm-2s-1. In parallel we are developing a new pipelined data acquisition system for the Belle detector to cope with higher trigger rates of up to 30 kHz and severe background conditions. In order to reduce development and maintenance costs, we have adopted a modular design for these new readout electronics. The chosen architecture consists of a common readout platform, upon which are mounted subdetector specific parts, customized to meet the readout requirements of each sub detector component. As an example of this new architecture, we present in this paper the design of drift chamber electronics. The drift chamber readout utilizes the AMT-3 time-to-digital converter chip, originally developed for the ATLAS experiment, which satisfies the performance requirement for current and future Belle drift chamber readout. A data transfer performance test with emulation modules, mounted on the common platform, shows that the new readout electronics works well at a more than 30 kHz input trigger rate. [ABSTRACT FROM AUTHOR]

This paper analyses the performance of the time domain reflectometry (TDR) technique when it is applied to the location of faults on cables. Different types of defects, which can arise on coaxial cables, are modelled and their reflection coefficients are calculated. The results, validated by experimental data, are compared to the typical noise that affects this kind of measurement to assess the sensitivity of the technique. Shield damage to a shielded twisted pair and a shielded multiwire cable is also examined: these examples represent more critical situations because the effect of cable and mismatching losses limits the dynamic range of the measurement. In both cases, the TDR allows us to locate faults that strongly affect the propagation of the signal on the transmission line, but the reflections produced by small defects are often masked by the noise. A data processing technique based on the comparison with a reference measurement and the use of the statistical correlation are then implemented. In this way, the reflections produced by the faults are much more visible and an overall enhancement of the technique sensitivity is achieved. [ABSTRACT FROM AUTHOR]

Abstract: To measure the muon decay parameters with high accuracy, we require an array of precision drift detector layers whose relative position is known with very high accuracy. This article describes the design, construction and performance of these detectors in the TWIST (TRIUMF Weak Interaction Symmetry Test) spectrometer. [Copyright &y& Elsevier]

Abstract: The HERA-B Outer Tracker is a large detector with 112,674 drift chamber channels. It is exposed to a particle flux of up to thus coping with conditions similar to those expected for the LHC experiments. The front-end readout system, based on the ASD-8 chip and a customized TDC chip, is designed to fulfil the requirements on low noise, high sensitivity, rate tolerance, and high integration density. The TDC system is based on an ASIC which digitizes the time in bins of about 0.5ns within a total of 256 bins. The chip also comprises a pipeline to store data from 128 events which is required for a deadtime-free trigger and data acquisition system. We report on the development, installation, and commissioning of the front-end electronics, including the grounding and noise suppression schemes, and discuss its performance in the HERA-B experiment. [Copyright &y& Elsevier]

Abstract: We present the construction of a planar drift chamber with wires stretched between two arms of a c-shaped aluminum frame. The special shape of the frame allows to extend the momentum acceptance of the COSY-11 detection system towards lower momenta without suppressing the high-momentum particles. The proposed design allows for construction of tracking detectors covering small angles with respect to the beam, which can be installed and removed without dismounting the beam-pipe. For a three-dimensional track reconstruction a computer code was developed using a simple algorithm of hit pre-selection. [Copyright &y& Elsevier]

Abstract: The Alice TPC Readout (ALTRO) chip is a mixed-signal ASIC, designed for the readout of the Time Projection Chamber (TPC) detector for the ALICE experiment at the CERN LHC. In one single chip, the analogue signals from 16 channels are digitized, processed, and stored in a multi-acquisition memory. In particular, ALTRO implements a set of signal processing algorithms to correct for various perturbations, which might be superimposed to the detector signal. Among these correction schemes are a tail cancellation filter and a baseline correction circuit. This paper addresses the performance of the ALTRO signal processing algorithms, as measured in a system consisting of 1024 channels and connected to a prototype of the ALICE TPC detector, to acquire cosmic ray signals. These measurements allow to conclude on some of the characteristics of the signal ion tail and on the effectiveness of the ALTRO signal processing, with emphasis on tail cancellation and baseline restoration. These tests show that the system meets all design requirements. [Copyright &y& Elsevier]

Abstract: The ATLAS Muon Spectrometer (ATLAS Collaboration, ATLAS Muon Spectrometer Technical Design Report CERN/LHCC/97-22, ATLAS TDR 10, 1997.) will use dedicated detectors to trigger on muons and to identify the bunch-crossing at the appropriate rate. The Spectrometer has been designed to perform stand-alone triggering and measurement of muon transverse momentum up to 1TeV with good resolution (from 3% up to 10% at 1TeV). The magnetic system is composed of three large superconducting air-core toroids instrumented with trigger and high-precision tracking chambers, a central part (barrel) composed of eight coils and two end-cap magnets. The high-precision tracking system is based on Monitored Drift Tube (MDT) and Cathode Strip Chambers (CSC) in the small angle-regions. The Level-1 trigger is provided by Resistive Plate Chambers (RPC) in the barrel and Thin Gap Chambers (TGC) in the end-cap. These detectors will also measure the track coordinates in the magnetic field direction (second coordinate), to complement the precision tracking provided by the MDT which only measure the track coordinates in the bending direction of the magnetic field. The trigger system covers an area of 3650m2 in the barrel and 2900m2 in the end-cap. In the barrel region three double-gap RPC stations are used, two in the middle and one in the outer MDT chamber layer. In the end-cap region one triple-gap TGC station is used, in front of the middle MDT station, and two double-gap TGC stations behind it. The mass production of both systems is under way. The systems were involved in extensive beam tests in 2002–2003, testing their compliance with LHC timing requirements using 25ns beam bunching to emulate the LHC beam structure, aging under critical environment conditions and so on. [Copyright &y& Elsevier]

Abstract: Timing RPCs are Resistive Plate Chambers made with glass and metal electrodes separated by precision spacers. Typical gas gaps are a few hundred micrometers wide. Such counters were introduced in 1999 and have since reached timing accuracies below 50ps with efficiencies above for MIPs. Applications in high-energy physics have already taken place with several more under study. Some recent developments include the extension of the counting rate capability by over one order of magnitude, to 25kHz/cm, with time resolutions below 100ps . A prototype RPC-based Positron Emission Tomograph yielded a reconstructed point-source resolution of mm FWHM and a modified timing RPC design, featuring m pitch anode strips, allowed to reach extremely good position resolution for hard X-rays in digital readout mode. An analytically solvable model has allowed us to clarify the basic factors influencing the time resolution. [Copyright &y& Elsevier]

Abstract: Resistive Plate Chambers have been chosen as dedicated trigger muon detectors for the Compact Muon Solenoid experiment at the Large Hadron Collider at CERN. The barrel RPC detector consists of 480 chambers of different forms and sizes, equipped with 75,000 strips and covering an area of about 2400 m. About one-third of RPC barrel chambers have been produced up to the end of 2003 and these 150 chambers, produced and assembled in Italy, have been extensively tested at the two Italian test stands of Bari and Pavia by the RPC barrel collaboration. Preliminary results of the production and test of the chambers will be described here. [Copyright &y& Elsevier]

Abstract: In order to investigate predictions concerning CP violation in the charged kaon sector, a new beam line providing concurrently K+ and K- has been constructed at CERN for the NA48/2 experiment. Several modifications and upgrades have been made in the apparatus; one of them being the implementation of a beam spectrometer named KABES. This detector is based on the time projection chamber principle; the amplification of the ionization signal is achieved by using Micromegas devices. The performance of KABES is found to be excellent in high-intensity hadron beams. The achieved space resolution of 100μm provides a measurement of track momentum with a precision better than 1% and the time resolution, better than 1ns, allows the charged kaons in NA48 to be identified with almost no ambiguity. The measurement of the direction and momentum of the K+ and K- tracks makes possible the precise study of their decay modes, particularly those for which one or more particles escape detection in the NA48 detector. [Copyright &y& Elsevier]

Abstract: The HADES dielectron spectrometer has recently launched its physics program at the heavy ion synchrotron SIS at GSI Darmstadt. The spectroscopy of vector mesons in heavy ion collisions via their dielectron decay channel makes great demands on the HADES tracking system regarding acceptance and spatial resolution. The tracking system is formed out of 24 low-mass, trapezoidal multi-layer drift chambers providing about of active area. Low multiple scattering in the in total four planes of drift chambers before and after the magnetic field is ensured by using helium-based gas mixtures and aluminum cathode and field wires. First in-beam performance results are contrasted with expectations from simulations. Emphasis is placed on the energy loss information, exploring its relevance regarding track recognition. [Copyright &y& Elsevier]

Abstract: The resolution and efficiency of a precision drift-tube chamber for the ATLAS muon spectrometer with final read-out electronics was tested at the Gamma Irradiation Facility at CERN in a muon beam at photon irradiation rates of up to , which corresponds to twice the highest background rate expected in ATLAS. A silicon strip detector telescope served as external reference in the beam. The pulse-height measurement of the read-out electronics was used to perform time-slewing corrections, which lead to an improvement of the average drift-tube resolution from 104 to without irradiation, and from 128 to at the maximum expected rate. The measured drift-tube efficiency agrees with the expectation from the dead time of the read-out electronics up to the maximum expected rate. [Copyright &y& Elsevier]

Abstract: The BaBar Drift Chamber is a cylindrical, small-cell drift chamber installed at the PEP-II B-Factory. It has been operating since May 1999, integrating nearly luminosity in collisions at . The chamber has accumulated a dose of 12.8mC/cm, resulting in a drop in gain of approximately 6.4%. The drift chamber has met most of its design goals (position, momentum, and dE/dx resolution) while maintaining extremely high efficiency for charged track reconstruction. The chamber''s operational history and performance will be presented, along with a discussion of the effects of aging and extrapolations for future performance, through 2008. [Copyright &y& Elsevier]

An X-ray setup has been developed to measure wire positions of straw tube drift chambers of the COMPASS experiment with a charge-coupled device. In an automatic scanning procedure wire positions can be determined with an accuracy better than 30 μm inside an area of 3.6 × 3.6 m2. This accuracy is achieved by means of multiple stereo recordings of the detector wires and external reference wires. Within small distances of several centimeters the achieved accuracy is on the order of a few micrometers. [ABSTRACT FROM AUTHOR]

Drift chamber readout electronics for over 8000 channels with concurrent data recording and readout have been developed to update the NA4S experiment existing system. Drift times are measured in bins of 1.56 its with respect to the continuously running 40 MHz experiment clock. The architecture is based on commercially available hardware for cost effectiveness and flexibility. The design of the electronics is described, and results from data-taking runs are presented. [ABSTRACT FROM AUTHOR]

Using prototype modules of the ALICE Transition Radiation Detector (TRD) we investigate space-charge effects and the dependence of the pion rejection performance on the incident angle of the ionizing particle. The average pulse height distributions in the drift chambers operated with the Xe,CO2(15%) mixture provide quantitative information on the gas gain reduction due to space charge accumulating during the drift of the primary ionization. Our results demonstrate that the pion rejection performance of a TRD is better for tracks which are not at normal incidence to the anode wires. We present detailed simulations of detector signals, which reproduce the measurements and lend strong support to our interpretation of the measurements in terms of space-charge effects. [Copyright &y& Elsevier]

The high acceptance di-electron spectrometer at the GSI, Darmstadt, Germany, heavy-ion synchrotron Schwerionen Synchrotron is a high-resolution second-generation detector system for lepton pair spectroscopy. Its low-mass tracking system consists of two pairs of planes of trapezoidally shaped multiwire drift chambers, installed on either side of a superconducting toroidal magnet. This paper summarizes our experience with the construction and in-beam operation of the six large-area chambers produced by Forschungszentrum Rossendorf. Studies on creeping of aluminum wires over a period of three years are presented. In addition, the observation of the growth of filaments with various shapes and sizes in one of the chambers used in-beam will be discussed in detail. [ABSTRACT FROM AUTHOR]

Electron ID and tracking in ALICE, in particular at the trigger level, require excellent TRD performance in terms of pion rejection and position resolution. We present results of prototype measurements in beams of 1–6 GeV/c. A position resolution down to 200 μm, angular resolution of 1° and pion rejection factors better than 100 are reached. Measurements of the ionization energy deposit and pure transition radiation spectrum are discussed. [Copyright &y& Elsevier]

We present measurements of drift velocities and gains in gas mixtures based on Ar and Xe, with CO2, CH4, and N2 as quenchers, and compare them with calculations. In particular, we show the dependence of Ar- and Xe–CO2 drift velocities and gains on the amount of nitrogen contamination in the gas, which in real experiments may build up through leaks. A quantification of the Penning mechanism which contributes to the Townsend coefficients of a given gas mixture is proposed. [Copyright &y& Elsevier]

We describe the design, construction, readout, tests, and performance of planar drift chambers, based on 5-mm-diameter copperized Mylar and Kapton straws, used in an experimental search for rare kaon decays. The experiment took place in the high-intensity neutral beam at the Alternating Gradient Synchrotron of Brookhaven National Laboratory, using a neutral beam stop, two analyzing dipoles, and redundant particle identification to remove backgrounds. [Copyright &y& Elsevier]

We present measurements of the transition radiation (TR) spectrum produced in an irregular radiator at different electron momenta. The data are compared to simulations of TR from a regular radiator. [Copyright &y& Elsevier]