I. L. Gavrilenko

The track reconstruction of modern high energy physics experiments is a very complex task that puts stringent requirements onto the software realisation. The ATLAS track reconstruction software has been in the past dominated by a collection of individual packages, each of which incorporating a different intrinsic event data model, different data flow sequences and calibration data. Recently, the ATLAS track reconstruction has undergone a major design revolution to ensure maintainability during the long lifetime of the ATLAS experiment and the flexibility needed for the startup phase. The entire software chain has been re-organised in modular components and a common event data model has been deployed. A complete new track reconstruction that concentrates on common tools aimed to be used by both ATLAS tracking devices, the Inner Detector and the Muon System, has been established. It has been already used during many large scale tests with data from Monte Carlo simulation and from detector commissioning projects such as the combined test beam 2004 and cosmic ray events. This document concentrates on the technical and conceptual details of the newly developed track reconstruction.

A straw proportional counter is the basic element of the ATLAS Transition Radiation Tracker (TRT). Its detailed properties as well as the main properties of a few TRT operating gas mixtures are described. Particular attention is paid to straw tube performance in high radiation conditions and to its operational stability.

We review the prospects for B-decay physics at the LHC as discussed in the 1999 workshop on Standard Model physics at the LHC. Contents

In this paper we study several fixed step and adaptive Runge-Kutta methods suitable for transporting track parameters through an inhomogeneous magnetic field. Moreover, we present a new adaptive Runge-Kutta-Nyström method which estimates the local error of the extrapolation without introducing extra stages to the original Runge-Kutta-Nyström method. Furthermore, these methods are compared for propagation accuracy and computing cost efficiency in the simultaneous track and error propagation (STEP) algorithm of the common ATLAS tracking software. The tests show the new adaptive Runge-Kutta-Nyström method to be the most computing cost efficient.

Abstract The most relevant properties for operation of straw proportional tubes at LHC are described. Particular attention is paid to the possibility of straw operation in a strong magnetic field and a high radiation environment.

A summary of the aging and material validation studies carried out for the ATLAS Transition Radiation Tracker (TRT) is presented. Particular emphasis is put on the different phenomena observed in straw tubes operating with the chosen Xe/CF4/CO2 mixture. The most serious effects observed are silicon deposition on the anode wire and damage of the anode wire gold plating. Etching phenomena and active radical effects are also discussed. With a careful choice of all materials and components, and with good control of the water contamination in the active gas, the ATLAS TRT will operate reliably for 10 years at the LHC design luminosity. To demonstrate this fully, more work is still needed on the gas system purification elements, in particular to understand their interplay with the active species containing fluorine created in the avalanche process under irradiation.

Results on analog front-end electronics and straw performance studies at high counting rates are described. Prototypes of the electronics have been tested at counting rates up to 17.5 MHz. A drift-time accuracy of 180 μm and a drift-time measurement efficiency of 53% were obtained at 17.5 MHz. The expected counting rate is between 5 and 15 MHz (depending on straw position) for the Atlas straw tracker at LHC design luminosity, leading to an estimated drift-time accuracy at 160 μm and hit registration efficiency of 68% for the average counting rate of 10 MHz. These results are in a good agreement with detailed MC simulations and could be improved with better front-end electronics.

A prototype of the Transition Radiation Tracker (TRT) for the ATLAS detector at the LHC has been built and tested. The TRT is an array of straw tubes which integrate tracking and electron identification by transition radiation into one device. Results of experimental measurements and of comparisons with Monte-Carlo simulations are presented for the electron identification performance as a function of various detector parameters. Under optimal operating conditions, a rejection against pions of a factor 100 was achieved with 90% electron efficiency.

An 864 channel prototype of an integrated straw tracker and transition radiation detector for tracking and electron identification has been tested with and without magnetic field at the CERN SPS. The rejection against hadrons and converted photons has been measured and the dependence of the rejection power on detection parameters has been investigated. Tracking and hadron rejection were also studied in a high multiplicity environment. The results are compared with Monte Carlo simulations. Wherever possible, conclusions are drawn concerning the performance of a full-scale detector at the future Large Hadron Collider.

In this paper we study the transport of track parameter covariance matrices—the so-called error propagation—in the inhomogeneous magnetic field of the ATLAS experiment. The Jacobian elements are transported in parallel with the track parameters, avoiding the inherent need of any purely numerical scheme of propagating a set of auxiliary tracks. We evaluate the quality of the transported Jacobians by a very thorough, purely numerical approach of obtaining the same derivatives, providing a quantitative understanding of the effects of including gradients of energy loss and the magnetic field on the accuracy of the error propagation. Irrespective of the accuracy of the underlying track parameter propagation, the method of parallel integration of the derivatives is demonstrated to be significantly faster than even the simplest numerical scheme. The error propagation presented in this paper is part of the simultaneous track and error propagation(STEP) algorithm of the common ATLAS tracking software.

A prototype of the Transition Radiation Tracker (TRT) for the ATLAS experiment at the CERN LHC has been built and tested at the CERN SPS. Detailed studies of the drift-time measurements, alignment technique, hit registration efficiency, track and momentum accuracy were performed. A coordinate measurement accuracy of 150μm for a single TRT drift tube and momentum resolution of 0.8% for 20GeV pions in a 1.56T magnetic field were achieved. The results obtained are in agreement with the expected tracking performance of the ATLAS TRT.

This paper presents a conceptual framework for understanding post-traumatic stress disorder (PTSD) and psychological battle fatigue (BF) as outcomes of mental adaptation to changing environmental conditions. These conditions are primarily linked to the experience of war, military threats, and the broader challenges of the global landscape. It is worth emphasizing that these challenges have, without exaggeration, affected the global population in 2022. The pressing need for research on PTSD and BF is driven not only by the significant shifts in global military events but also by the absence of fundamental methodological research that aligns with the demands of the 21st century. The author has identified crucial issues that form the basis for further comprehensive scientific and practical investigations. The overarching goal of this research is to develop effective methodologies and establish rehabilitation programs tailored to the specific needs of combatants, internally displaced individuals, and civilians residing in war-affected regions.

Abstract The capabilities of the ATLAS detector for B physics are described. After an introduction outlining the features of the detector relevant for B physics, studies of B event reconstruction are presented. There follows a discussion of CP violation analyses that can be performed, with estimates of the precision that can be obtained. Finally, other B physics topics, including B s 0 mixing, rare decays and measurements with B baryons, are discussed.

A small set of final prototypes of the ATLAS Inner Detector silicon tracking system(Pixel Detector and SemiConductor Tracker), were used to take data during the 2004 Combined Test Beam. Data were collected from runs with beams of different flavour (electrons, pions, muons and photons) with a momentum range of 2 to 180 GeV/c. Four independent methods were used to align the silicon modules. The corrections obtained were validated using the known momenta of the beam particles and were shown to yield consistent results among the different alignment approaches. From the residual distributions, it is concluded that the precision attained in the alignmentof the silicon modules is of the order of 5 mm in their most precise coordinate.