Tracking properties of the ATLAS Transition Radiation Tracker (TRT)

D V Krasnopevtsev

doi:10.1088/1742-6596/798/1/012150

Abstract

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.

Highlights

The ATLAS detector [1] at the Large Hadron Collider (LHC) is a general-purpose detector designed to make precision measurements of known physics processes and to probe new physics at the energy frontier of the LHC
At the centre of the detector is an optimised, multi-technology tracking detector (Inner 23 Detector, Inner Detector (ID)) [2] embedded in a 2 T axial magnetic field produced by a solenoid
Low occupancy conditions To suppress the effect of the occupancy, baseline Transition Radiation Tracker (TRT) performance studies are first performed at relatively low straw occupancy conditions with the pp data collected with a 50 ns bunch interval

Summary

Introduction

The ATLAS detector [1] at the LHC is a general-purpose detector designed to make precision measurements of known physics processes and to probe new physics at the energy frontier of the LHC. The straw efficiency is defined as the probability for the straw to produce a signal above the LL threshold for a particle traversing the straw gas volume This efficiency decreases for the highest value of the track-to-wire distance, but on average is about 96% for a typical straw channel and is practically constant thought the entire detector. The position residual is defined as the difference between the measured drift radius and the track-to-wire distance It is shown, for an average number of interactions per bunch crossing μ of 580 10. High levels of agreement between simulation and data were observed for precision hit fraction and track measurement accuracy as function of μ for TRT barrel and end-caps.

Conclusions

Findings

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