ATLAS Transition Radiation Tracker Research Articles

Study of performance of the ATLAS transition radiation tracker in run 1 of the LHC: Tracking characteristics

The ATLAS Transition Radiation Tracker (TRT) contains more than 350000 large straw tubes and it is the outermost of the three subsystems of the ATLAS Inner Detector (ID). The TRT contributes substantially to the ATLAS ID resolution for the tracks of high-energy particles, providing excellent particle identification capabilities and electron-pion separation. Basic performance parameters of the TRT related to its tracking function are described in this paper. The data used in this study were collected during the first period of the Large Hadron Collider (LHC) operation in 2012 with a proton collision energy of 8 TeV. The tracking performance of the TRT has been studied in the case of operating with a Xe-based gas mixture and as a function of the straw occupancy. Special attention was paid to investigation of tracking parameters inside hadronic jets. The experimental data and simulation are in reasonable agreement, even within the dense cores of the most energetic jets.

Performance of the ATLAS Transition Radiation Tracker in Run 1 of the LHC: tracker properties

The tracking performance parameters of the ATLAS Transition Radiation Tracker (TRT) as part of the ATLAS inner detector are described in this paper for different data-taking conditions in proton-proton, proton-lead and lead-lead collisions at the Large Hadron Collider (LHC). The performance is studied using data collected during the first period of LHC operation (Run 1) and is compared with Monte Carlo simulations. The performance of the TRT, operating with two different gas mixtures (xenon-based and argon-based) and its dependence on the TRT occupancy is presented. These studies show that the tracking performance of the TRT is similar for the two gas mixtures and that a significant contribution to the particle momentum resolution is made by the TRT up to high particle densities.

Tracking properties of the ATLAS Transition Radiation Tracker (TRT)

The tracking performance parameters of the ATLAS Transition Radiation Tracker (TRT) as part of the ATLAS Inner Detector (ID) are described for different data taking conditions in proton-proton collisions at the Large Hadron Collider (LHC). These studies are performed using data collected during the first (Run 1) and the second (Run 2) periods of LHC operation and are compared with Monte Carlo simulations. The performance of the TRT, operating with xenon-based (Xe-based) and argon-based (Ar-based) gas mixtures and its dependence on the TRT occupancy is presented. No significant degradation of position measurement accuracy was found up to occupancies of about 20% in Run 1. The relative number of reconstructed tracks in ID that also have a extension in the TRT was observed to be almost constant with the increase of occupancies up to 50%. Even in configurations where tracks are close to each other, the reconstruction algorithm is still able to find the correct TRT hits and properly reconstruct the tracks.

ATLAS Transition Radiation Tracker (TRT): Straw tubes for tracking and particle identification at the Large Hadron Collider

The ATLAS Transition Radiation Tracker (TRT) is the outermost of the three inner detector tracking subsystems and consists of ∼300,000 thin-walled drift tubes (“straw tubes”) that are 4mm in diameter. The TRT system provides ∼30 space points with ∼130micron resolution for charged tracks with |η|<2 and pT>0.5GeV/c. The TRT also provides electron identification capability by detecting transition radiation (TR) X-ray photons in an Xe-based working gas mixture.Compared to Run 1, the LHC beams now provide a higher centre of mass energy (13TeV), more bunches with a reduced spacing (25ns), and more particles in each bunch leading to very challenging, higher occupancies in the TRT. Significant modifications of the TRT detector have been made for LHC Run 2 mainly to improve response to the expected much higher rate of hits and to mitigate leaks of the Xe-based active gas mixture. The higher rates required changes to the data acquisition system and introduction of validity gate to reject out-of-time hits. Many gas leaks were repaired and the gas system was modified to use a cheaper Ar-based gas mixture in some channels. A likelihood method was introduced to optimise the TRT electron identification.

Gas gain stabilisation in the ATLAS TRT detector

The ATLAS (one of two general purpose detectors at the LHC) Transition Radiation Tracker (TRT) is the outermost of the three tracking subsystems of the ATLAS Inner Detector. It is a large straw-based detector and contains about 350,000 electronics channels. The performance of the TRT as tracking and particularly particle identification detector strongly depends on stability of the operation parameters with most important parameter being the gas gain which must be kept constant across the detector volume. The gas gain in the straws can vary significantly with atmospheric pressure, temperature, and gas mixture composition changes. This paper presents a concept of the gas gain stabilisation in the TRT and describes in detail the Gas Gain Stabilisation System (GGSS) integrated into the Detector Control System (DCS). Operation stability of the GGSS during Run-1 is demonstrated.

Simulation of the transition radiation detection conditions in the ATLAS TRT detector filled with argon and krypton gas mixtures

Performance of the Transition Radiation Tracker (TRT) at the ATLAS experiment with argon and krypton gas mixtures was simulated. The efficiency of transition radiation registration, which is necessary for electron identification, was estimated along with the electron identification capabilities under such conditions.

TRTViewer: Monitoring and Diagnostic Tool for the TRT Detector of the ATLAS Experiment at LHC

TRTViewer is the dedicated software tool for monitoring of the ATLAS Transition Radiation Tracker (TRT) performance at dif- ferent electronics levels: individual channels, readout chips or electronic boards. It can use several sources of input information – from direct DAQ stream or raw data files to ROOT files with processed analysis histograms. Using TRTViewer one can quickly estimate the TRT operational parameters – occupancy, efficiency, timing, reveal problematic regions with noisy, dead or inefficient channels, check calibration uniformity, etc. This tool is widely used by shifters in ATLAS Control Room and also by TRT experts during electronics installation, tuning, operation control and express-offline data analysis.

ATLAS Transition Radiation Tracker (TRT): Straw tube gaseous detectors at high rates

The ATLAS Transition Radiation Tracker (TRT) is the outermost of the three tracking subsystems of the ATLAS Inner Detector. The ATLAS detector is located at LHC/CERN. We report on how these gaseous detectors (“straw tubes”) are performing during the ATLAS 2011 and 2012 runs where the TRT experiences higher rates than previously encountered. The TRT contains around 300000 thin-walled proportional-mode drift tubes providing on average 30 two-dimensional space points with an intrinsic resolution of approximately 120μm for charged particle tracks with |η|<2 and pT>0.5GeV. Along with continuous tracking, the TRT provides electron identification capability through the detection of transition radiation X-ray photons. During the ATLAS 2012 proton–proton data runs, the TRT is operating successfully while being subjected to the highest rates of incident particles ever experienced by a large scale gaseous tracking system. In the second half of 2012, the TRT has collected data in an environment with instantaneous proton–proton luminosity around 0.8×1034cm−2s−1. While shadowing effects caused by up to 40 simultaneous proton–proton collisions per bunch crossing are noticeable, the TRT performs significantly better than design. It also contributes to the combined tracking system pT resolution and to electron identification. During LHC heavy ion running in 2011, the TRT contributed to measuring track pT even in events where overall occupancy exceeded 50%.

Silicon strip detectors for ATLAS at the HL-LHC upgrade

The present ATLAS silicon strip tracker (SCT) and transition radiation tracker (TRT) are to be replaced with new silicon strip detectors as part of the inner tracker system (ITK) for the Phase-II upgrade of the Large Hadron Collider, HL-LHC. We have carried out intensive R&D programs based on n+-on-p microstrip detectors to fabricate improved radiation hard strip detectors that can survive the radiation levels corresponding to the integrated luminosity of up to 3000fb−1. We describe the main specifications for this year's sensor fabrication and the related R&D results, followed by a description of the candidate schema for module integration.

Performance of the ATLAS transition radiation tracker readout with high energy collisions at theLHC

The ATLAS Transition Radiation Tracker is the outermost of the three subsystems of the ATLAS Inner Detector. It contributes significantly to the precision of the momentum measurement of charged particles and to the identification of electrons. On the TRT front end electronics this is realized by discriminating the straw signal against two separate thresholds: a low one for tracking and a high one for electron identification. The electronics can also be configured to provide a trigger signal, which has been utilized to build a cosmic ray trigger that became extremely useful for the TRT as well as other subdetectors during ATLAS commissioning. This note will describe the TRT readout electronics and data acquisition, with emphasis on the experience gained during the first years of operation.

Performance of the ATLAS Transition Radiation Tracker

The ATLAS Transition Radiation Tracker (TRT) is a large straw tube tracking system that is the outermost of the three subsystems of the ATLAS Inner Detector (ID). With over 350,000 readout channels, the TRT provides both excellent particle identification capabilities and electron-pion separation, as well as contributing significantly to the resolution for high-pt tracks in the ID. As the instantaneous luminosity of the LHC increases, the occupancy of the TRT will increase as well. The low-occupancy tracking resolution and efficiency will be presented, as will be studies of resolution and PID at higher occupancies.

The ATLAS transition radiation tracker

The transition radiation tracker of the ATLAS setup, which is one of the two multipurpose detectors at the Large Hadron Collider (LHC), its design, and the tasks it performs are described. The tracker is fully assembled and commissioned. The first physical results obtained by the tracker in the ATLAS cosmic muon runs are presented.

A study of the gas filter efficiency in the closed circulation system of the ATLAS transition radiation tracker

Results of investigations of the gas filter in the circulation system of the ATLAS transition radiation tracker are presented. A prototype of the circulation gas system and a technique for investigating radiation ageing in it are described. The ageing rate in the system with and without the gas filter being installed has been measured.

The ATLAS TRT and its Performance at LHC

The ATLAS Transition Radiation Tracker (TRT) is the outermost of the three subsystems of the ATLAS Inner Detector at the Large Hadron Collider at CERN. It consists of almost 300000 thin-wall drift tubes (straws) providing on average 30 two-dimensional space points with 0.12-0.15 mm resolution for charged particle tracks with |η| < 2 and pT > 0.5 GeV/c. Along with continuous tracking, it provides particle identification capability through the detection of transition radiation X-ray photons generated by high velocity particles in the many polymer fibers or films that fill the spaces between the straws. Custom-built analog and digital electronics is optimized to operate as luminosity increases to the LHC design. In this talk, a review of the commissioning and first and current operational experience of the TRT detector and its performance at LHC will be presented. Emphasis will be given to performance studies based on the reconstruction and analysis of LHC collisions. A comparison of the TRT response and the particle identification in pp and Pb-Pb collisions will be presented. The results are also compared with the expected performance.

Commissioning and Performance of the ATLAS Transition Radiation Tracker with First High Energy pp and Pb-Pb collisions at LHC

Abstract The ATLAS Transition Radiation Tracker (TRT) is the outermost of the three sub-systems of the ATLAS Inner Detector at the Large Hadron Collider at CERN. It consists of close to 300000 thin-wall drift tubes (straws) providing ∼30 measurements with position resolution of about 120 μm for charged particle tracks with |η| pT > 0.5 GeV. Along with continuous tracking, it provides particle identification capability through the detection of transition radiation, X-ray photons generated by high momentum particles in the many polymer fibers or films that fill the spaces between the straws. Custom-built analog and digital electronic read-out are optimized to operate at the LHC design luminosity. In this article, a review of the commissioning and first operational experience of the TRT detector will be presented. Emphasis will be given to performance studies based on the reconstruction and analysis of proton-proton collision data collected at the LHC. In addition, the response of the TRT detector to the extremely high track density conditions encountered during the first heavy ion LHC collisons will be presented.

Commissioning and Performance of the ATLAS Transition Radiation Tracker with high energy collisions at LHC

The ATLAS Transition Radiation Tracker (TRT) is the outermost of the three sub-systems of the ATLAS Inner Detector at the Large Hadron Collider at CERN. It consists of close to 300,000 thin-wall drift-tubes (straws) providing on average 30 two-dimensional space points for charged particle tracks. The straws have 0.13 mm resolution and measure tracks with | η | < 2 and p T > 0.5 GeV / c . Along with continuous tracking, it provides particle identification capability through the detection of transition radiation X-ray photons generated by high Lorenz gamma particles in the many polymer fibers or films that fill the spaces between the straws. In this talk, a review of the commissioning and first operational experience of the TRT detector will be presented. Emphasis will be given to performance studies based on the reconstruction and analysis of LHC proton-proton collisions.

Performance of the ATLAS Transition Radiation Tracker read-out with cosmic rays and first high energy collisions at the LHC

The Transition Radiation Tracker (TRT) is the outermost of the three subsystems in the ATLAS Inner Detector. It contributes significantly to the precision of the momentum measurement of charged particles and to the identification of electrons. This note reports about the commissioning and performance of the TRT with cosmic rays and the first high energy collisions at the LHC.

Commissioning and performance of the ATLAS Transition Radiation Tracker with cosmic rays and first high energy collisions

The Transition Radiation Tracker is the outermost of the three subsystems in the ATLAS Inner Detector. It contributes significantly to the precision of the momentum measurement of charged particles and to the identification of electrons. This note reports about the recent commissioning progress and the performance achieved in preparation for first collisions at the LHC.

The ATLAS Transition Radiation Tracker (TRT) proportional drift tube: design and performance

A straw proportional counter is the basic element of theATLAS Transition Radiation Tracker (TRT). Its detailed properties aswell as the main properties of a few TRT operating gas mixtures aredescribed. Particular attention is paid to straw tube performance inhigh radiation conditions and to its operational stability.

The ATLAS TRT Barrel Detector

The ATLAS TRT barrel is a tracking drift chamber using52,544 individual tubular drift tubes. It is one part of the ATLASInner Detector, which consists of three sub-systems: the pixeldetector spanning the radius range 4 to 20 cm, the semiconductortracker (SCT) from 30 to 52 cm, and the transition radiation tracker(TRT) from 56 to 108 cm. The TRT barrel covers the centralpseudo-rapidity region |η|< 1, and the TRT while endcaps coverthe forward and backward eta regions. These TRT systems provide acombination of continuous tracking with many measurements inindividual drift tubes (or straws) and of electron identificationbased on transition radiation from fibers or foils interleaved betweenthe straws themselves. This paper describes the recently-completedconstruction of the TRT Barrel detector, including the quality controlprocedures used in the fabrication of the detector.