1. |
- Aad, G., et al.
(författare)
-
The ATLAS Experiment at the CERN Large Hadron Collider
- 2008
-
Ingår i: Journal of Instrumentation. - 1748-0221. ; 3:S08003
-
Forskningsöversikt (refereegranskat)abstract
- The ATLAS detector as installed in its experimental cavern at point 1 at CERN is described in this paper. A brief overview of the expected performance of the detector when the Large Hadron Collider begins operation is also presented.
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2. |
- Abat, E., et al.
(författare)
-
A layer correlation technique for pion energy calibration at the 2004 ATLAS Combined Beam Test
- 2011
-
Ingår i: Journal of Instrumentation. - : Institute of Physics (IOP). - 1748-0221. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- A new method for calibrating the hadron response of a segmented calorimeter is developed and successfully applied to beam test data. It is based on a principal component analysis of energy deposits in the calorimeter layers, exploiting longitudinal shower development information to improve the measured energy resolution. Corrections for invisible hadronic energy and energy lost in dead material in front of and between the calorimeters of the ATLAS experiment were calculated with simulated Geant4 Monte Carlo events and used to reconstruct the energy of pions impinging on the calorimeters during the 2004 Barrel Combined Beam Test at the CERN H8 area. For pion beams with energies between 20 GeV and 180 GeV, the particle energy is reconstructed within 3% and the energy resolution is improved by between 11% and 25% compared to the resolution at the electromagnetic scale.
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3. |
- Abat, E., et al.
(författare)
-
Combined performance studies for electrons at the 2004 ATLAS combined test-beam
- 2010
-
Ingår i: Journal of Instrumentation. - : Institute of Physics (IOP). - 1748-0221. ; 5, s. P11006-
-
Tidskriftsartikel (refereegranskat)abstract
- In 2004 at the ATLAS (A Toroidal LHC ApparatuS) combined test beam, one slice of the ATLAS barrel detector (including an Inner Detector set-up and the Liquid Argon calorimeter) was exposed to particles from the H8 SPS beam line at CERN. It was the first occasion to test the combined electron performance of ATLAS. This paper presents results obtained for the momentum measurement p with the Inner Detector and for the performance of the electron measurement with the LAr calorimeter (energy E linearity and resolution) in the presence of a magnetic field in the Inner Detector for momenta ranging from 20 GeV/c to 100 GeV/c. Furthermore the particle identification capabilities of the Transition Radiation Tracker, Bremsstrahlungs-recovery algorithms relying on the LAr calorimeter and results obtained for the E/p ratio and a way how to extract scale parameters will be discussed.
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4. |
- Abat, E., et al.
(författare)
-
Photon reconstruction in the ATLAS Inner Detector and Liquid Argon Barrel Calorimeter at the 2004 Combined Test Beam
- 2011
-
Ingår i: Journal of Instrumentation. - 1748-0221. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- The reconstruction of photons in the ATLAS detector is studied with data taken during the 2004 Combined Test Beam, where a full slice of the ATLAS detector was exposed to beams of particles of known energy at the CERN SPS. The results presented show significant differences in the longitudinal development of the electromagnetic shower between converted and unconverted photons as well as in the total measured energy. The potential to use the reconstructed converted photons as a means to precisely map the material of the tracker in front of the electromagnetic calorimeter is also considered. All results obtained are compared with a detailed Monte-Carlo simulation of the test-beam setup which is based on the same simulation and reconstruction tools as those used for the ATLAS detector itself.
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5. |
- Abat, E., et al.
(författare)
-
Study of the response of the ATLAS central calorimeter to pions of energies from 3 to 9 GeV
- 2009
-
Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002 .- 1872-9576. ; 607:2, s. 372-386
-
Tidskriftsartikel (refereegranskat)abstract
- A fully instrumented slice of the ATLAS central detector was exposed to test beams from the SPS (Super Proton Synchrotron) at CERN in 2004. in this paper, the response of the central calorimeters to pions with energies in the range between 3 and 9 GeV is presented. The linearity and the resolution of the combined calorimetry (electromagnetic and hadronic calorimeters) was measured and compared to the prediction of a detector simulation program using the toolkit Geant 4. (C) 2009 Elsevier B.V. All rights reserved.
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6. |
- Abat, E., et al.
(författare)
-
The ATLAS Transition Radiation Tracker (TRT) proportional drift tube: design and performance
- 2008
-
Ingår i: Journal of Instrumentation. - 1748-0221. ; 3:2
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
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7. |
- Abat, E., et al.
(författare)
-
The ATLAS TRT barrel detector
- 2008
-
Ingår i: Journal of Instrumentation. - 1748-0221. ; 3
-
Tidskriftsartikel (refereegranskat)abstract
- The ATLAS TRT barrel is a tracking drift chamber using 52,544 individual tubular drift tubes. It is one part of the ATLAS Inner Detector, which consists of three sub-systems: the pixel detector spanning the radius range 4 to 20 cm, the semiconductor tracker (SCT) from 30 to 52 cm, and the transition radiation tracker ( TRT) from 56 to 108 cm. The TRT barrel covers the central pseudo-rapidity region |eta| < 1, while the TRT endcaps cover the forward and backward eta regions. These TRT systems provide a combination of continuous tracking with many measurements in individual drift tubes ( or straws) and of electron identification based on transition radiation from fibers or foils interleaved between the straws themselves. This paper describes the recently-completed construction of the TRT Barrel detector, including the quality control procedures used in the fabrication of the detector.
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8. |
- Abat, E., et al.
(författare)
-
The ATLAS TRT electronics
- 2008
-
Ingår i: Journal of Instrumentation. - 1748-0221. ; 3:6
-
Tidskriftsartikel (refereegranskat)abstract
- The ATLAS inner detector consists of three sub-systems: the pixel detector spanning the radius range 4cm-20cm, the semiconductor tracker at radii from 30 to 52 cm, and the transition radiation tracker (TRT), tracking from 56 to 107 cm. 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 transition radiation from fibres or foils interleaved between the straws themselves. This paper describes the on and off detector electronics for the TRT as well as the TRT portion of the data acquisition (DAQ) system.
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9. |
- Abata, E., et al.
(författare)
-
Study of energy response and resolution of the ATLAS barrel calorimeter to hadrons of energies from 20 to 350 GeV
- 2010
-
Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576 .- 0167-5087. ; 621:1-3, s. 134-150
-
Tidskriftsartikel (refereegranskat)abstract
- A fully instrumented slice of the ATLAS detector was exposed to test beams from the SPS (Super Proton Synchrotron) at CERN in 2004. In this paper, the results of the measurements of the response of the barrel calorimeter to hadrons with energies in the range 20-350 GeV and beam impact points and angles corresponding to pseudo-rapidity values in the range 0.2-0.65 are reported. The results are compared to the predictions of a simulation program using the Geant 4 toolkit. (C) 2010 Published by Elsevier B.V.
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10. |
- Abate, E., et al.
(författare)
-
Combined performance tests before installation of the ATLAS Semiconductor and Transition Radiation Tracking Detectors
- 2008
-
Ingår i: Journal of Instrumentation. - 1748-0221. ; 3
-
Tidskriftsartikel (refereegranskat)abstract
- The ATLAS (A Toroidal LHC ApparatuS) Inner Detector provides charged particle tracking in the centre of the ATLAS experiment at the Large Hadron Collider (LHC). The Inner Detector consists of three subdetectors: the Pixel Detector, the Semiconductor Tracker (SCT), and the Transition Radiation Tracker (TRT). This paper summarizes the tests that were carried out at the final stage of SCT+TRT integration prior to their installation in ATLAS. The combined operation and performance of the SCT and TRT barrel and endcap detectors was investigated through a series of noise tests, and by recording the tracks of cosmic rays. This was a crucial test of hardware and software of the combined tracker detector systems. The results of noise and cross-talk tests on the SCT and TRT in their final assembled configuration, using final readout and supply hardware and software, are reported. The reconstruction and analysis of the recorded cosmic tracks allowed testing of the offline analysis chain and verification of basic tracker performance parameters, such as efficiency and spatial resolution, in combined operation before installation.
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11. |
- Almehed, Sverker, et al.
(författare)
-
Regional research exploitation of the LHC: A case-study of the required computing resources
- 2002
-
Ingår i: Computer Physics Communications. - 0010-4655. ; 145:3, s. 341-350
-
Tidskriftsartikel (refereegranskat)abstract
- A simulation study to evaluate the required computing resources for a research exploitation of the Large Hadron Collider (LHC) has been performed. The evaluation,vas done as a case study. assuming existence of a Nordic regional centre and using the requirements for per-forming a specific physics analysis as a yard-stick. Other input parameters were: assumption for the distribution of researchers at the institutions involved, an analysis model, and two different functional structures of the computing resources.
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12. |
- Anghinolfi, Francisco, et al.
(författare)
-
DTMROC-S: Deep submicron version of the readout chip for the TRT detector in ATLAS
- 2002
-
Ingår i: 8th Workshop On Electronics For LHC Experiments. ; , s. 95-99
-
Konferensbidrag (refereegranskat)abstract
- A new version of the circuit for the readout of the ATLAS straw tube detector, TRT [1], has been developed in a deep-submicron process. The DTMROC-S is fabricated in a commercial 0.25μm CMOS IBM technology, with a library hardened by layout techniques [2]. Compared to the previous version of the chip [3] done in a 0.8μm radiation-hard CMOS and despite of the features added for improving the robustness and testability of the circuit, the deep-submicron technology results in a much smaller chip size that increases the production yield and lowers the power consumption.
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13. |
- Burckhart, H.J., et al.
(författare)
-
ATLAS Status and First Run Scenarios for B Physics
- 2007
-
Ingår i: Nuclear Physics B (Proc. Suppl.). - 0920-5632. ; 170, s. 257-263
-
Konferensbidrag (refereegranskat)abstract
- This article summarizes the status of the ATLAS detector and its commissioning as of autumn 2006, one year before the expected LHC start-up. The initial running scenarios and goals for B physics are presented for the foreseen pilot run with 900 GeV centre-of-mass energy in autumn 2007, as well as for the first physics run in 2008 at the nominal centre-of-mass energy of 14 TeV.
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14. |
- Capeans, M., et al.
(författare)
-
Recent aging studies for the ATLAS transition radiation tracker
- 2004
-
Ingår i: IEEE Transactions on Nuclear Science. ; 51, s. 960-967
-
Konferensbidrag (refereegranskat)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 /spl sim/10 C/cm of wire and radiation doses of about 10 Mrad and 2/spl times/10/sup 14/ neutrons/cm/sup 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/sub 2/-3%O/sub 2/. It is planned to occasionally flush and operate the TRT detector with an Ar-based ternary mixture, containing a small percentage of CF/sub 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.
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15. |
- Chang, CH, et al.
(författare)
-
BCVEGPY: an event generator for hadronic production of the B-c meson
- 2004
-
Ingår i: Computer Physics Communications. - : Elsevier BV. - 0010-4655. ; 159:3, s. 192-224
-
Tidskriftsartikel (refereegranskat)abstract
- We have written a Fortran program BCVEGPY, which is an event generator for the hadronic production of the B-c meson through the dominant hard subprocess gg --> B-c(B-c(*)) + b + c. To achieve a compact program, we have written the amplitude of the subprocess with the particle helicity technique and made it as symmetric as possible, by decomposing the gluon self couplings and then applying the symmetries. To check the program, various cross sections of the subprocess have been computed numerically and compared with those in the literature. BCVEGPY is written in a PYTHIA-compatible format, thus it is easy to implement in PYTHIA.
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16. |
- Cwetanski, P, et al.
(författare)
-
Acceptance tests and criteria of the ATLAS transition radiation tracker
- 2005
-
Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499. ; 52:6, s. 2911-2916
-
Tidskriftsartikel (refereegranskat)abstract
- The Transition Radiation Tracker (TRT) sits at the outermost part of the ATLAS Inner Detector, encasing the Pixel Detector and the Semi-Conductor Tracker (SCT). The TRT combines charged particle track reconstruction with electron identification capability. This is achieved by layers of xenonfilled straw tubes with periodic radiator foils or fibers providing TR photon emission. The design and choice of materials have been optimized to cope with the harsh operating conditions at the LHC, which are expected to lead to an accumulated radiation dose of 10 Mrad and a neutron fluence of up to 2 . 10(14) n/cm(2) after ten years of operation. The TRT comprises a barrel containing 52 000 axial straws and two end-cap parts with 320 000 radial straws. The total of 420 000 electronic channels (two channels per barrel straw) allows continuous tracking with many projective measurements (more than 30 straw hits per track). The assembly of the barrel modules in the US has recently been completed, while the end-cap wheel construction in Russia has reached the 50% mark. After testing at the production sites and shipment to CERN, all modules and wheels undergo a series of quality and conformity measurements. These acceptance tests survey dimensions, wire tension, gas-tightness, high-voltage stability and gas-gain uniformity along each individual straw. This paper gives details on the acceptance criteria and measurement methods. An overview of the most important results obtained to-date is also given.
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17. |
- De Angelis, Alessandro, et al.
(författare)
-
An investigation of screwiness in hadronic final states from DELPHI
- 1998
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- A recent theoretical model by Andersson et al. proposes that soft gluons order themselves in the form of a helix at the end of the QCD cascades. The Authors of the model present a measure of the rapidity-azimuthal angle correlation, which they call screwiness. We searched for such a signal in DELPHI data, and found no evidence for screwiness.
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18. |
- Driouichi, Chafik, et al.
(författare)
-
Observation potential of the decays B0s,d → J/ψη
- 2002
-
Ingår i: EPJ direct. - 1435-3725. ; 4:CN2, s. 1-13
-
Tidskriftsartikel (refereegranskat)abstract
- The observation potential of the decays B0s,d → J/ψη with the ATLAS detector at the LHC is described in this paper. At present there exist only upper limits for the branching fractions, but at LHC, a clear signal for the decay mode B0s,d → J/ψη is expected. The branching fraction of this decay mode can thus be measured, and other parameters such as B0s lifetime can be measured as well. The decay mode B0s → J/ψη is analogous to the mode B0s → J/ψφ, which has been studied extensively in view of CP violation measurements. In these two decay modes, the CP asymmetry predicted by the Standard Model is very small, and the observation of a sizeable effect would be a signal of physics beyond the Standard Model. The decay mode J/ψη constitutes thus a cross-check for the mode J/ψφ. Furthermore, the former final state is a CP-eigenstate and no angular analysis is thus needed. The reconstruction of η-mesons at LHC experiments has not been addressed before, and therefore the study presented here can also be regarded as an example of the physics prospects with η-mesons at the LHC.
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19. |
- Eerola, Paula, et al.
(författare)
-
Accelerator-based infrastructures in the fields of particle and nuclear physics
- 2020
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The Council for Research Infrastructures (RFI) within the Swedish Research Council (Vetenskapsrådet) commits a significant part of its annual budget to accelerator-based infrastructures in particle and nuclear physics. The funding covers membership fees, running costs and investments. The Swedish activities in these fields are mainly focused on CERN (Geneva, Switzerland) and FAIR (Darmstadt, Germany). In 2019, RFI decided to commission an investigation and landscape analysis of the research infrastructures they fund in these fields. The report is meant to support the Council’s work in ensuring that these funds are strategically well-spent and of maximum benefit to the research community. A panel of seven experts from the Nordic countries have worked on the task with the aid of data from relevant documentation, hearings, interviews and questionnaires. The report contains several concrete recommendations given from the authors to RFI.
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20. |
- Eerola, Paula
(författare)
-
ATLAS B physics performance update
- 2004
-
Ingår i: AIP Conference Proceedings. - : AIP. - 1551-7616 .- 0094-243X. ; 722, s. 242-248
-
Konferensbidrag (refereegranskat)abstract
- An update of the B physics performance of the ATLAS experiment is presented. After a short review of B production and decays at LHC, the main features of the ATLAS detector are described, and the present construction status is shown. Physics topics which are presented are: precision measurements, rare decays, and B production. It is shown that despite of recent changes in the trigger strategy and initial detector layout, ATLAS retains an excellent potential for measurements of sin2β and rare dimuon decays. A large spectrum of B physics studies is also feasible - here we present examples of precision measurements with Bs0 mesons, Bc mesons, and B production
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21. |
- Eerola, Paula, et al.
(författare)
-
Atlas Data-Challenge 1 on NorduGrid
- 2003
-
Konferensbidrag (refereegranskat)abstract
- The first LHC application ever to be executed in a computational Grid environment is the so-called ATLAS Data-Challenge 1, more specifically, the part assigned to the Scandinavian members of the ATLAS Collaboration. Taking advantage of the NorduGrid testbed and tools, physicists from Denmark, Norway and Sweden were able to participate in the overall exercise starting in July 2002 and continuing through the rest of 2002 and the first part of 2003 using solely the NorduGrid environment. This allowed to distribute input data over a wide area, and rely on the NorduGrid resource discovery mechanism to find an optimal cluster for job submission. During the whole Data-Challenge 1, more than 2 TB of input data was processed and more than 2.5 TB of output data was produced by more than 4750 Grid jobs.
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22. |
- Eerola, Paula, et al.
(författare)
-
Atlas Data-Challenge 1 on NorduGrid
- 2003
-
Ingår i: Proceedings of CHEP 2003.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The first LHC application ever to be executed in a computational Grid environment is the so-called ATLAS Data-Challenge 1, more specifically, the part assigned to the Scandinavian members of the ATLAS Collaboration. Taking advantage of the NorduGrid testb
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23. |
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24. |
- Eerola, Paula, et al.
(författare)
-
Building a Production Grid in Scandinavia
- 2003
-
Ingår i: IEEE Internet Computing. - : IEEE. ; 7:4, s. 27-35
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The aim of the NorduGrid project is to build and operate a production grid infrastructure in Scandinavia and Finland. By developing innovative middleware solutions, it enables a 24/7 production-level test bed. Through a common access layer, NorduGrid conn
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25. |
- Eerola, Paula, et al.
(författare)
-
Roadmap for the ARC Grid Middleware
- 2007
-
Ingår i: Lecture Notes in Computer Science. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783540757542 ; 4699/2007, s. 471-479
-
Konferensbidrag (refereegranskat)abstract
- The Advanced Resource Connector (ARC) or the NorduGrid middleware is an open source software solution enabling production quality computational and data Grids, with special emphasis on scalability, stability, reliability and performance. Since its first release in May 2002, the middleware is deployed and being used in production environments. This paper aims to present the future development directions and plans of the ARC middleware in terms of outlining the software development roadmap.
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26. |
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27. |
- Eerola, Paula, et al.
(författare)
-
The NorduGrid architecture and tools
- 2003
-
Konferensbidrag (refereegranskat)abstract
- The NorduGrid project designed a Grid architecture with the primary goal to meet the requirements of production tasks of the LHC experiments. While it is meant to be a rather generic Grid system, it puts emphasis on batch processing suitable for problems encountered in High Energy Physics. The NorduGrid architecture implementation uses the Globus ToolkitTM as the foundation for various components, developed by the project. While introducing new services, the NorduGrid does not modify the Globus tools, such that the two can eventually co-exist. The NorduGrid topology is decentralized, avoiding a single point of failure. The NorduGrid architecture is thus a light-weight, non-invasive and dynamic one, while robust and scalable, capable of meeting most challenging tasks of High Energy Physics.
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28. |
- Eerola, Paula, et al.
(författare)
-
The NorduGrid architecture and tools
- 2003
-
Ingår i: Proceedings of CHEP 2003.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The NorduGrid project designed a Grid architecture with the primary goal to meet the requirements of production tasks of the LHC experiments. While it is meant to be a rather generic Grid system, it puts emphasis on batch processing suitable for problems
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29. |
- Eerola, Paula, et al.
(författare)
-
The Nordugrid production grid infrastructure, status and plans
- 2003
-
Ingår i: Proceedings. Fourth International Workshop on Grid Computing. - 076952026X ; , s. 158-165
-
Konferensbidrag (refereegranskat)abstract
- Nordugrid offers reliable grid services for academic users over an increasing set of computing & storage resources spanning through the Nordic countries Denmark, Finland, Norway and Sweden. A small group of scientists has already been using the Nordugrid as their daily computing utility. In the near future we expect a rapid growth both in the number of active users and available resources thanks to the recently launched Nordic grid projects.We report on the present status and short term plans of the Nordic grid infrastructure and describe the available and foreseen resources, grid services and our forming user base
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30. |
- Eerola, Paula, et al.
(författare)
-
The NorduGrid production Grid infrastructure, status and plans
- 2003
-
Ingår i: Proc. Fourth International Workshop on Grid Computing. ; , s. 158-165
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- NorduGrid offers reliable Grid services for academic users over an increasing set of computing & storage resources spanning through the Nordic countries Denmark, Finland, Norway and Sweden. A small group of scientists has already been using the NorduGrid
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31. |
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32. |
- Kainu, T, et al.
(författare)
-
Somatic deletions in hereditary breast cancers implicate 13q21 as a putative novel breast cancer susceptibility locus
- 2000
-
Ingår i: Proceedings of the National Academy of Sciences. - 1091-6490. ; 97:17, s. 9603-9608
-
Tidskriftsartikel (refereegranskat)abstract
- A significant proportion of familial breast cancers cannot be explained by mutations in the BRCA1 or BRCA2 genes. We applied a strategy to identify predisposition loci for breast cancer by using mathematical models to identify early somatic genetic deletions in tumor tissues followed by targeted linkage analysis. Comparative genomic hybridization was used to study 61 breast tumors from 37 breast cancer families with no identified BRCA1 or BRCA2 mutations. Branching and phylogenetic tree models predicted that loss of 13q was one of the earliest genetic events in hereditary cancers. In a Swedish family with five breast cancer cases, all analyzed tumors showed distinct 13q deletions, with the minimal region of loss at 13q21-q22. Genotyping revealed segregation of a shared 13q21 germ-line haplotype in the family. Targeted linkage analysis was carried out in a set of 77 Finnish, Icelandic, and Swedish breast cancer families with no detected BRCA1 and BRCA2 mutations. A maximum parametric two-point logarithm of odds score of 2.76 was obtained for a marker at 13q21 (D13S1308, theta = 0.10). The multipoint logarithm of odds score under heterogeneity was 3.46. The results were further evaluated by simulation to assess the probability of obtaining significant evidence in favor of linkage by chance as well as to take into account the possible influence of the BRCA2 locus, located at a recombination fraction of 0.25 from the new locus. The simulation substantiated the evidence of linkage at D13S1308 (P < 0.0017). The results warrant studies of this putative breast cancer predisposition locus in other populations.
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33. |
- Konstantinov, A., et al.
(författare)
-
Data management services of NorduGrid
- 2005
-
Ingår i: CERN-2005-002. ; 2, s. 765-766
-
Konferensbidrag (refereegranskat)abstract
- In common grid installations, services responsible for storing big data chunks, replication of those data and indexing their availability are usually completely decoupled. And a task of synchronizing data is passed to either user-level tools or separate services (like spiders) which are subject to failure and usually cannot perform properly if one of underlying services fails too. The NorduGrid Smart Storage Element (SSE) was designed to try to overcome those problems by combining the most desirable features into one service. It uses HTTPS/G for secure data transfer, Web Services for control (through same HTTPS/G channel) and can provide information to indexing services used in middlewares based on the Globus Toolkit (TM). At the moment, those are the Replica Catalog and the Replica Location Service. The modular internal design of the SSE and the power of C++ object programming allows to add support for other indexing services in an easy way. There are plans to complement it with a Smart Indexing Service capable of resolving inconsistencies hence creating a robust distributed data storage system.
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34. |
- Langgard Nielsen, J., et al.
(författare)
-
Experiences with Data Indexing services supported by the NorduGrid middleware
- 2005
-
Ingår i: CERN-2005-002. ; 2, s. 673-675
-
Konferensbidrag (refereegranskat)abstract
- The NorduGrid middleware, ARC, has integrated support for querying and registering to Data Indexing services such as the Globus Replica Catalog and Globus Replica Location Server. This support allows one to use these indexing services for for example brokering during jobsubmission, automatic registration of files and many other things. This integrated support is complemented by a set of command-line tools for registering to and querying these Data Indexing services. In this article we will describe experiences with these indexing services both from a daily work point of view and in production environments such as the Atlas Data- Challenges 1 and 2. We will describe the advantages of such Data Indexing services as well as their shortcomings. Finally we will present a proposal for an extended Smart Indexing Service which should deal with the shortcomings described. Such an indexing service is being designed at the moment.
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35. |
- Pajchel, K., et al.
(författare)
-
Usage statistics and usage patterns on the NorduGrid: Analyzing the logging information collected on one of the largest production Grids of the world
- 2005
-
Ingår i: CERN-2005-002. ; 2, s. 711-714
-
Konferensbidrag (refereegranskat)abstract
- The Nordic Grid facility (NorduGrid [1]) came into operation during summer 2002 when the Scandinavian ATLAS HEP group started to use the Grid for the ATLAS Data Challenges (DC) and was thus the first Grid ever contributing to an ATLAS production. Since then, the Grid facility has been in continuous 24/7 operation. NorduGrid is being used by a growing set of active users from various scientific areas including physics, chemistry, biology and informatics. It has given major contributions to the ATLAS Data Challenge 1 [2] and the ongoing Data Challenge 2. · The increasing number of resources has made NorduGrid one of the largest production Grids in the world, continuously running on more than 30 sites more than 3000 CPUs. · The resources range from small test clusters at academic institutions to large farms at several supercomputer centers and the NorduGrid software runs on clusters with very different Linux distributions. This presentation gives a short overview of the design and implementation of the NorduGrid middleware, logging and monitoring facilities. It will be followed by a description of a typical job on NorduGrid and the information about its parameters which are monitored online and persistified in the logging service.
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36. |
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37. |
- Smirnova, Oxana, et al.
(författare)
-
The NorduGrid Architecture And Middleware for Scientific Applications
- 2003
-
Ingår i: Lecture Notes in Computer Science. - Berlin, Heidelberg : Springer Berlin Heidelberg. ; 2657, s. 264-273
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The NorduGrid project operates a production Grid infrastructure in Scandinavia and Finland using own innovative middleware solutions. The resources range from small test clusters at academic institutions to large farms at several supercomputer centers, a
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38. |
- Sturrock, R., et al.
(författare)
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Performance of the NorduGrid ARC and the Dulcinea Executor in ATLAS Data Challenge 2
- 2005
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Ingår i: CERN-2005-002. ; 2, s. 1095-1098
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Konferensbidrag (refereegranskat)abstract
- This talk describes the various stages of ATLAS Data Challenge 2 (DC2) in what concerns usage of resources deployed via NorduGrid's Advanced Resource Connector (ARC). It also describes the integration of these resources with the ATLAS production system using the Dulcinea executor. ATLAS Data Challenge 2 (DC2), run in 2004, was designed to be a step forward in the distributed data processing. In particular, much coordination of task assignment to resources was planned to be delegated to Grid in its different flavours. An automatic production management system was designed, to direct the tasks to Grids and conventional resources. The Dulcinea executor is a part of this system that provides interface to the information system and resource brokering capabilities of the ARC middleware. The executor translates the job definitions recieved from the supervisor to the extended resource specification language (XRSL) used by the ARC middleware. It also takes advantage of the ARC middleware's built-in support for the Globus Replica Location Server (RLS) for file registration and lookup. NorduGrid's ARC has been deployed on many ATLAS-dedicated resources across the world in order to enable effective participation in ATLAS DC2. This was the first attempt to harness large amounts of strongly heterogeneous resources in various countries for a single collaborative exercise using Grid tools. This talk addresses various issues that arose during different stages of DC2 in this environment: preparation, such as ATLAS software installation; deployment of the middleware; and processing. The results and lessons are summarized as well.
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39. |
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40. |
- Åkesson, Torsten, et al.
(författare)
-
Aging studies for the ATLAS Transition Radiation Tracker (TRT)
- 2003
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 515:1-2, s. 166-179
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Konferensbidrag (refereegranskat)abstract
- 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.
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41. |
- Åkesson, Torsten, et al.
(författare)
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An X-ray scanner for wire chambers
- 2003
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 507:3, s. 622-635
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Tidskriftsartikel (refereegranskat)abstract
- The techniques to measure the position of sense wires and field wires, the gas gain and the gas flow rate inside wire chambers using a collimated and filtered X-ray beam are reported. Specific examples are given using barrel modules of the Transition Radiation Tracker of the ATLAS experiment. (C) 2003 Elsevier B.V. All rights reserved.
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42. |
- Åkesson, Torsten, et al.
(författare)
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ATLAS computing: Technical Design Report
- 2005
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The ATLAS Computing Model embraces the Grid paradigm and a high degree of decentralization and sharing of computing resources. The required level of computing resources means that off-site facilities will be vital to the operation of ATLAS in a way that was not the case for previous CERN-based experiments. The primary event processing occurs at CERN in a Tier-0 facility. The RAW data is archived at CERN and copied (along with the primary processed data) to the Tier-1 facilities around the world. These facilities archive the raw data, provide the reprocessing capacity, provide access to the various processed versions, and allow scheduled analysis of the processed data by physics analysis groups. Derived datasets produced by the physics groups are copied to the Tier-2 facilities for further analysis. The Tier-2 facilities also provide the simulation capacity for the experiment, with the simulated data housed at Tier-1s. In addition, Tier-2 centres will provide analysis facilities, and some will provide the capacity to produce calibrations based on processing raw data. A CERN Analysis Facility provides an additional analysis capacity, with an important role in the calibration and algorithmic development work. ATLAS has adopted an object-oriented approach to software, based primarily on the C++ programming language, but with some components implemented using FORTRAN and Java. A component-based model has been adopted, whereby applications are built up from collections of plug-compatible components based on a variety of configuration files. This capability is supported by a common framework that provides common data-processing support. This approach results in great flexibility in meeting the basic processing needs of the experiment, and also for responding to changing requirements throughout its lifetime. The heavy use of abstract interfaces allows for different implementations to be provided, supporting different persistency technologies, or optimized for the offline or high-level trigger environments. The Athena framework is an enhanced version of the Gaudi framework that was originally developed by the LHCb experiment, but is now a common ATLAS-LHCb project. Major design principles are the clear separation of data and algorithms, and of transient (in-memory) and persistent (in-file) data. All levels of processing of ATLAS data, from high-level trigger to event simulation, reconstruction and analysis, take place within the Athena framework; in this way it is easier for code developers and users to test and run algorithmic code, with the assurance that all geometry and conditions data will be the same for all types of applications (simulation, reconstruction, analysis, visualization). One of the principal challenges for ATLAS computing is to develop and operate a data storage and management infrastructure able to meet the demands of a yearly data volume of O(10 PB) utilized by data processing and analysis activities spread around the world. The ATLAS Computing Model establishes the environment and operational requirements that ATLAS data-handling systems must support, and, together with the operational experience gained to date in test beams and data challenges, provides the primary guidance for the development of the data management systems. The ATLAS Databases and Data Management Project (DB Project) leads and coordinates ATLAS activities in these areas, with a scope encompassing technical databases (detector production, installation and survey data), detector geometry, online/TDAQ databases, conditions databases (online and offline), event data, offline processing configuration and book-keeping, distributed data management, and distributed database and data management services. The project is responsible for ensuring the coherent development, integration, and operational capability of the distributed database and data management software and infrastructure for ATLAS across these areas. The ATLAS Computing Model foresees the distribution of raw and processed data to Tier-1 and Tier-2 centres, so as to be able to exploit fully the computing resources that are made available to the Collaboration. Additional computing resources will be available for data processing and analysis at Tier-3 centres and other computing facilities to which ATLAS may have access. A complex set of tools and distributed services, enabling the automatic distribution and processing of the large amounts of data, has been developed and deployed by ATLAS in cooperation with the LHC Computing Grid (LCG) Project and with the middleware providers of the three large Grid infrastructures we use: EGEE, OSG and NorduGrid. The tools are designed in a flexible way, in order to have the possibility to extend them to use other types of Grid middleware in the future. These tools, and the service infrastructure on which they depend, were initially developed in the context of centrally managed, distributed Monte Carlo production exercises. They will be re-used wherever possible to create systems and tools for individual users to access data and compute resources, providing a distributed analysis environment for general usage by the ATLAS Collaboration. The first version of the production system was deployed in summer 2004 and has been used since the second half of 2004. It was used for Data Challenge 2, for the production of simulated data for the 5th ATLAS Physics Workshop (Rome, June 2005) and for the reconstruction and analysis of the 2004 Combined Test-Beam data. The main computing operations that ATLAS will have to run comprise the preparation, distribution and validation of ATLAS software, and the computing and data management operations run centrally on Tier-0, Tier-1s and Tier-2s. The ATLAS Virtual Organization will allow production and analysis users to run jobs and access data at remote sites using the ATLAS-developed Grid tools. In the past few years the Computing Model has been tested and developed by running Data Challenges of increasing scope and magnitude, as was proposed by the LHC Computing Review in 2001. We have run two major Data Challenges since 2002 and performed other massive productions in order to provide simulated data to the physicists and to reconstruct and analyse real data coming from test-beam activities; this experience is now useful in setting up the operations model for the start of LHC data-taking in 2007. The Computing Model, together with the knowledge of the resources needed to store and process each ATLAS event, gives rise to estimates of required resources that can be used to design and set up the various facilities. It is not assumed that all Tier-1s or Tier-2s will be of the same size; however, in order to ensure a smooth operation of the Computing Model, all Tier-1s should have broadly similar proportions of disk, tape and CPU, and the same should apply for the Tier-2s. The organization of the ATLAS Software & Computing Project reflects all areas of activity within the project itself. Strong high-level links have been established with other parts of the ATLAS organization, such as the T-DAQ Project and Physics Coordination, through cross-representation in the respective steering boards. The Computing Management Board, and in particular the Planning Officer, acts to make sure that software and computing developments take place coherently across sub-systems and that the project as a whole meets its milestones. The International Computing Board assures the information flow between the ATLAS Software & Computing Project and the national resources and their Funding Agencies.
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43. |
- Åkesson, Torsten, et al.
(författare)
-
ATLAS High-Level Trigger, Data Acquisition and Controls Technical Design Report
- 2003
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This Technical Design Report (TDR) for the High-level Trigger (HLT), Data Acquisition (DAQ) and Controls of the ATLAS experiment builds on the earlier documents published on these systems: Trigger Performance Status Report, DAQ, EF, LVL2 and DCS Technical Progress Report, and High-Level Triggers, DAQ and DCS Technical Proposal. Much background and preparatory work relevant to this TDR is referenced in the above documents. In addition, a large amount of detailed technical documentation has been produced in support of this TDR. These documents are referenced in the appropriate places in the following chapters. This section introduces the overall organization of the document. The following sections give an overview of the principal system requirements and functions, as well as a brief description of the principal data types used in the Trigger/DAQ (TDAQ) system. The document has been organized into four parts: Part I — Global View Chapters 2, 3 and 4 address the principal system and experiment parameters which define the main requirements of the HLT, DAQ and Controls system. The global system operations, and the physics requirements and event selection strategy are also addressed. Chapter 5 defines the overall architecture of the system and analyses the requirements of its principal components, while Chapters 6 and 7 address more specific fault-tolerance and monitoring issues. Part II — System Components This part describes in more detail the principal components and functions of the system. Chapter 8 addresses the final prototype design and performance of the Data Flow component. These are responsible for the transport of event data from the output of the detector Read Out Links (ROLs) via the HLT system (where event selection takes place) to mass storage. Chapter 9 explains the decomposition of the HLT into a second level trigger (LVL2) and an Event Filter (EF). It details the design of the data flow within the HLT, the specifics of the HLT system supervision, and the design and implementation of the Event Selection Software (ESS). Chapter 10 addresses the Online Software which is responsible for the run control and DAQ supervision of the entire TDAQ and detector systems during data taking. It is also responsible for miscellaneous services such as error reporting, run parameter accessibility, and histogramming and monitoring support. Chapter 11 describes the Detector Control System (DCS), responsible for the control and supervision of all the detector hardware and of the services and the infrastructure of the experiment. The DCS is also the interface point for information exchange between ATLAS and the LHC accelerator. Chapter 12 draws together the various aspects of experiment control detailed in previous chapters and examines several use-cases for the overall operation and control of the experiment, including: data-taking operations, calibration runs, and operations required outside data-taking. Part III — System Performance Chapter 13 addresses the physics selection. The tools used for physics selection are described along with the event-selection algorithms and their performance. Overall HLT output rates and sizes are also discussed. An initial analysis of how ATLAS will handle the first year of running from the point of view of TDAQ is presented. Chapter 14 discusses the overall performance of the HLT/DAQ system from various points of view, namely the HLT performance as evaluated in dedicated testbeds, the overall performance of the TDAQ system in a testbed of ~10% ATLAS size, and functional tests of the system in the detector test beam environment. Data from these various testbeds are also used to calibrate a detailed discrete-event -simulation model of data flow in the full-scale system. Part IV — Organization and Planning Chapter 15 discusses quality-assurance issues and explains the software-development process employed. Chapter 16 presents the system costing and staging scenario. Chapter 17 presents the overall organization of the project and general system-resource issues. Chapter 18 presents the short-term HLT/DAQ work-plan for the next phase of the project as well as the global development schedule up to LHC turn-on in 2007.
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44. |
- Åkesson, Torsten, et al.
(författare)
-
ATLAS Transition Radiation Tracker test-beam results
- 2004
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 522:1-2, s. 50-55
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Konferensbidrag (refereegranskat)abstract
- 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.
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45. |
- Åkesson, Torsten, et al.
(författare)
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High transverse momentum physics at the large hadron collider
- 2002
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Ingår i: EPJ direct. - 1435-3725. ; 4:CN1, s. 1-61
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Forskningsöversikt (refereegranskat)abstract
- This note summarizes many detailed physics studies done by the ATLAS and CMSCollab orations for the LHC, concentrating on processes involving the production of high mass states. These studies show that the LHC should be able to elucidate the mechanism of electroweak symmetry breaking and to study a variety of other topics related to physics at the TeV scale. In particular, a Higgs boson with couplings given by the Standard Model is observable in several channels over the full range of allowed masses. Its mass and some of its couplings will be determined. If supersymmetry is relevant to electroweak interactions, it will be discovered and the properties of many supersymmetric particles elucidated. Other new physics, such as the existence of massive gauge bosons and extra dimensions can be searched for extending existing limits by an order of magnitude or more.
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46. |
- Åkesson, Torsten, et al.
(författare)
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Implementation of the DTMROC-S ASIC for the ATLAS TRT Detector in a 0.25μm CMOS technology
- 2003
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Ingår i: IEEE Nuclear Science Symposium and Medical Imaging Conference. - 1082-3654. - 0780376366 ; 1, s. 549-553
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Konferensbidrag (refereegranskat)abstract
- The DTMROC-S is a 16-channeI front-end chip developed for the signal processing of the ATLAS straw tube detector, TRT. Due to a highly radioactive environment, the chip is fabricated in a commercial 0.25μm CMOS technology hardened by layout techniques and, in addition, a special methodology was used to improve the circuit's robustness against Single Events Effects (SEE) caused by ionizing particles. Exhaustive internal test features were foreseen to simplify and ensure comprehensive design verification, high fault coverage and throughput. Compared to the previous version of the chip done in a 0.8μm radiation-hard CMOS and despite of all supplementary features, the Deep-Sub-Micron (DSM) technology results in a much smaller chip size that increases the production yield and lowers the power consumption.
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47. |
- Åkesson, Torsten, et al.
(författare)
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Operation of the ATLAS Transition Radiation Tracker under very high irradiation at the CERN LHC
- 2004
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 522:1-2, s. 25-32
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Konferensbidrag (refereegranskat)abstract
- 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. (C) 2004 Elsevier B.V. All rights reserved.
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48. |
- Åkesson, Torsten, et al.
(författare)
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Status of design and construction of the Transition Radiation Tracker (TRT) for the ATLAS experiment at the LHC
- 2004
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - : Elsevier BV. - 0167-5087 .- 0168-9002. ; 522:1-2, s. 131-145
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Tidskriftsartikel (refereegranskat)abstract
- The ATLAS Inner Detector consists of three sub-systems, the Pixel Detector at the innermost radius, the Semi-Conductor 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. (C) 2004 Elsevier B.V. All rights reserved.
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49. |
- Åkesson, Torsten, et al.
(författare)
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Tracking performance of the transition radiation tracker prototype for the ATLAS experiment
- 2002
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0167-5087. ; 485:3, s. 298-310
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Tidskriftsartikel (refereegranskat)abstract
- 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 150 Pin for a single TRT drift tube and momentum resolution of 0.8% for 20 GeV pions in a 1.56 T magnetic field were achieved. The results obtained are in agreement with the expected tracking performance of the ATLAS TRT. (C) 2001 Published by Elsevier Science B.V.
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50. |
- Öhman, Henrik
(författare)
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Searches for Higgs bosons with hadronically decaying τ-leptons : Using Grid and Cloud computing techniques
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis describes a measurement of the Standard Model Higgs boson coupling to fermions in decays to two τ-leptons, a search for charged Higgs bosons in decays to a τ-lepton and a neutrino, as well as the reconstruction, identification and triggering of hadronically decaying τ-leptons. The data considered are collected by the ATLAS experiment at the Large Hadron Collider.The reconstruction and identification of hadronically decaying τ-leptons in the ATLAS experiment during Run 2 of the Large Hadron Collider are described, and the performance of the τ trigger is measured in events with top–antitop-quark pairs using data from 13 TeV proton–proton collisions, corresponding to an integrated luminosity of 3.2 fb-1, collected in 2015, and 11.5 fb-1, collected in 2016.Hadronically decaying τ-leptons are of importance to many physical processes involving Higgs bosons. The coupling of the Standard Model Higgs boson to fermions is measured in decays to two τ-leptons using 7 TeV data corresponding to an integrated luminosity of 4.5 fb-1, collected in 2011, and 8 TeV data corresponding to an integrated luminosity of 20.3 fb-1, collected in 2012. The signal strength is measured to be μ = 1.4, corresponding to an excess over the background-only model of 4.5σ.Charged Higgs bosons are searched for in decays to a τ-lepton and a neutrino, where the τ-lepton decays hadronically. 13 TeV data corresponding to an integrated luminosity of 14.7 fb-1, collected in 2015 and 2016, are used. No excess over the Standard Model background is observed, and the 95 % confidence-level exclusion limits on σ(pp → [b]tH+) × (H+ → τν) are set to 2.0 pb–8 fb in the range 200–2000 GeV.
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