| 1. |
- Aad, G., et al.
(författare)
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Commissioning of the ATLAS Muon Spectrometer with cosmic rays
- 2010
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 70:3, s. 875-916
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Tidskriftsartikel (refereegranskat)abstract
- The ATLAS detector at the Large Hadron Collider has collected several hundred million cosmic ray events during 2008 and 2009. These data were used to commission the Muon Spectrometer and to study the performance of the trigger and tracking chambers, their alignment, the detector control system, the data acquisition and the analysis programs. We present the performance in the relevant parameters that determine the quality of the muon measurement. We discuss the single element efficiency, resolution and noise rates, the calibration method of the detector response and of the alignment system, the track reconstruction efficiency and the momentum measurement. The results show that the detector is close to the design performance and that the Muon Spectrometer is ready to detect muons produced in high energy proton-proton collisions.
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| 2. |
- Aad, G., et al.
(författare)
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The ATLAS Inner Detector commissioning and calibration
- 2010
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 70:3, s. 787-821
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Tidskriftsartikel (refereegranskat)abstract
- The ATLAS Inner Detector is a composite tracking system consisting of silicon pixels, silicon strips and straw tubes in a 2 T magnetic field. Its installation was completed in August 2008 and the detector took part in data-taking with single LHC beams and cosmic rays. The initial detector operation, hardware commissioning and in-situ calibrations are described. Tracking performance has been measured with 7.6 million cosmic-ray events, collected using a tracking trigger and reconstructed with modular pattern-recognition and fitting software. The intrinsic hit efficiency and tracking trigger efficiencies are close to 100%. Lorentz angle measurements for both electrons and holes, specific energy-loss calibration and transition radiation turn-on measurements have been performed. Different alignment techniques have been used to reconstruct the detector geometry. After the initial alignment, a transverse impact parameter resolution of 22.1 +/- 0.9 mu m and a relative momentum resolution sigma (p) /p=(4.83 +/- 0.16)x10(-4) GeV(-1)xp (T) have been measured for high momentum tracks.
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| 3. |
- Aad, G., et al.
(författare)
-
The ATLAS Simulation Infrastructure
- 2010
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044 .- 1434-6052. ; 70:3, s. 823-874
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Tidskriftsartikel (refereegranskat)abstract
- The simulation software for the ATLAS Experiment at the Large Hadron Collider is being used for large-scale production of events on the LHC Computing Grid. This simulation requires many components, from the generators that simulate particle collisions, through packages simulating the response of the various detectors and triggers. All of these components come together under the ATLAS simulation infrastructure. In this paper, that infrastructure is discussed, including that supporting the detector description, interfacing the event generation, and combining the GEANT4 simulation of the response of the individual detectors. Also described are the tools allowing the software validation, performance testing, and the validation of the simulated output against known physics processes.
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| 4. |
- Boelaert, Nele, et al.
(författare)
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Dijet angular distributions at root s=14 TeV
- 2010
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 66:3-4, s. 343-357
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Tidskriftsartikel (refereegranskat)abstract
- We present a Monte Carlo study of dijet angular distributions at root s = 14 TeV. First we perform a next-to- leading order QCD study; we calculate the distributions in four different bins of dijet invariant mass using different Monte Carlo programs and different jet algorithms, and we also investigate the systematic uncertainties coming from the choice of the parton distribution functions and the renormalization and factorization scales. In the second part of this paper, we present the effects on the distributions coming from a model including gravitational scattering and black hole formation in a world with large extra dimensions. Assuming a 25% systematic uncertainty, we report a discovery potential for the mass bin 1 < M-jj < 2 TeV at 10 pb(-1) integrated luminosity.
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| 5. |
- Boelaert, Nele
(författare)
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Dijet angular distributions in proton-proton collisions at root s = 7 TeV and root s = 14 TeV
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Dijet angular distributions provide an excellent tool for looking at high transverse momentum parton interactions in order to study both QCD and new physics processes. With the Large Hadron Collider (LHC) recently brought into use, an unprecedented energy regime has opened up. ATLAS is one of the experiments at the LHC. Its high performance calorimeter system providing near hermetic coverage in the pseudorapidity range $|\eta| < 4.9$, enables ATLAS to perform reliable jet measurements. Detailed Monte Carlo studies at $\sqrt{s}$ = 14 TeV, the LHC design collision energy, and at $\sqrt{s}$ = 7 TeV, the collision energy foreseen for the initial years of the LHC operation, clearly show that dijet angular distributions can be used to discriminate the Standard Model from a new physics model describing gravitational scattering and black hole formation in large extra dimensions. When considering only the shape of the distributions, both the theoretical and the experimental uncertainties are predicted to be small in those regions where new physics is expected to show up. The study at $\sqrt{s}$ = 7 TeV indicates that ATLAS is already sensitive to large extra-dimensional gravity mediated effects with 1 pb$^{-1}$ of data. The first measurement of dijet angular distributions at $\sqrt{s}$ = 7 TeV with ATLAS was carried out in two mass bins, using data that were recorded early 2010, corresponding to an integrated luminosity of about 15 nb$^{-1}$. The measurement shows good agreement with QCD predictions and demonstrates that ATLAS is ready to search for new physics in the dijet angular distributions with more data.
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