Operation of the ATLAS Transition Radiation Tracker under very high irradiation at the CERN LHC

The ATLAS Transition Radiation Tracker (TRT) performance depends critically on the choice of the active gas and on its properties. The most important operational aspects, which have led to the final choice of the active gas for the operation of the TRT at the LHC design luminosity, are presented. The TRT performance expected at these conditions is reviewed, including pile-up effects at high luminosity. (9 refs)

Recent aging studies for the ATLAS transition radiation tracker

The transition radiation tracker (TRT) is one of the three subsystems of the inner detector of the ATLAS experiment. It is designed to operate for 10 yr at the LHC, with integrated charges of similar to 10 C/cm of wire and radiation doses of about 10 Mrad and 2 multiplied by 10**1**4 neutrons/cm**2. These doses translate into unprecedented ionization currents and integrated charges for a large-scale gaseous detector. This paper describes studies leading to the adoption of a new ionization gas regime for the ATLAS TRT. In this new regime, the primary gas mixture is 70%Xe-27%CO**2-3%O**2. It is planned to occasionally flush and operate the TRT detector with an Ar-based ternary mixture, containing a small percentage of CF**4, to remove, if needed, silicon pollution from the anode wires. This procedure has been validated in realistic conditions and would require a few days of dedicated operation. This paper covers both performance and aging studies with the new TRT gas mixture. 12 Refs

ATLAS Transition Radiation Tracker test-beam results

Several prototypes of the Transition Radiation Tracker for the ATLAS experiment at the LHC have been built and tested at the CERN SPS accelerator. Results from detailed studies of the straw-tube hit registration efficiency and drift-time measurements and of the pion and electron spectra without and with radiators are presented. (10 refs)

Status of design and construction of the transition radiation tracker (TRT) for the ATLAS experiment at the LHC

The ATLAS Inner Detector consists of three sub-systems, the pixel detector at the innermost radius, the semiconductor tracker at intermediate radii, and the transition radiation tracker (TRT) at the outermost radius in front of the electromagnetic calorimeter. The TRT provides a combination of continuous tracking with many projective measurements based on individual drift-tubes (or straws) and of electron identification based on radiator fibres or foils interleaved between the straws themselves. This paper describes the current status of design and construction of the various components of the TRT: the assembly of the barrel modules has recently been completed, that of the end-cap wheels is well underway, and the on-detector front-end electronics is in production. The detector modules and front-end electronics boards will be integrated together over the next year, the barrel and end-cap TRT parts will be assembled and tested with their SCT counterparts during 2005 and installation and commissioning in the ATLAS pit will take place at the end of 2005 and the beginning of 2006. (8 refs)

Recent Aging Studies for the ATLAS Transition Radiation Tracker

Abstract-The transition radiation tracker (TRT) is one of the three subsystems of the inner detector of the ATLAS experiment. It is designed to operate for 10 yr at the LHC, with integrated charges of 10 C cm of wire and radiation doses of about 10 Mrad and 2 10 14 neutrons cm 2 . These doses translate into unprecedented ionization currents and integrated charges for a large-scale gaseous detector.This paper describes studies leading to the adoption of a new ionization gas regime for the ATLAS TRT. In this new regime, the primary gas mixture is 70%Xe-27%CO 2 -3%O 2 . It is planned to occasionally flush and operate the TRT detector with an Ar-based ternary mixture, containing a small percentage of CF 4 , to remove, if needed, silicon pollution from the anode wires. This procedure has been validated in realistic conditions and would require a few days of dedicated operation. This paper covers both performance and aging studies with the new TRT gas mixture