| 1. |
- Cwetanski, P, et al.
(författare)
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Acceptance tests and criteria of the ATLAS transition radiation tracker
- 2005
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Ingår i: IEEE Transactions on Nuclear Science. - 0018-9499. ; 52:6, s. 2911-2916
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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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| 2. |
- Åkesson, Torsten, et al.
(författare)
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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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| 3. |
- 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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| 4. |
- 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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| 5. |
- 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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| 6. |
- Åkesson, Torsten, et al.
(författare)
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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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| 7. |
- Efimenko, E., et al.
(författare)
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Extreme plasma states in laser-governed vacuum breakdown
- 2018
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 8:1
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Tidskriftsartikel (refereegranskat)abstract
- Triggering vacuum breakdown at laser facility is expected to provide rapid electron-positron p air production for studies in laboratory astrophysics and fundamental physics. However, the density of the produced plasma may cease to increase at a relativistic critical density, when the plasma becomes opaque. Here, we identify the opportunity of breaking this limit using optimal beam configuration of petawatt-class lasers. Tightly focused laser fields allow generating plasma in a small focal volume much less than λ 3 and creating extreme plasma states in terms of density and produced currents. These states can be regarded to be a new object of nonlinear plasma physics. Using 3D QED-PIC simulations we demonstrate a possibility of reaching densities over 10 25 cm -3, which is an order of magnitude higher than expected earlier. Controlling the process via initial target parameters provides an opportunity to reach the discovered plasma states at the upcoming laser facilities.
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| 8. |
- Gonoskov, Arkady, 1984, et al.
(författare)
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Extended particle-in-cell schemes for physics in ultrastrong laser fields : Review and developments
- 2015
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Ingår i: Physical Review E. Statistical, Nonlinear, and Soft Matter Physics. - 1539-3755 .- 1550-2376. ; 92:2
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Tidskriftsartikel (refereegranskat)abstract
- We review common extensions of particle-in-cell (PIC) schemes which account for strong field phenomena in laser-plasma interactions. After describing the physical processes of interest and their numerical implementation, we provide solutions for several associated methodological and algorithmic problems. We propose a modified event generator that precisely models the entire spectrum of incoherent particle emission without any low-energy cutoff, and which imposes close to the weakest possible demands on the numerical time step. Based on this, we also develop an adaptive event generator that subdivides the time step for locally resolving QED events, allowing for efficient simulation of cascades. Further, we present a unified technical interface for including the processes of interest in different PIC implementations. Two PIC codes which support this interface, PICADOR and ELMIS, are also briefly reviewed.
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| 9. |
- Gonoskov, Arkady, 1984, et al.
(författare)
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Ultrabright GeV Photon Source via Controlled Electromagnetic Cascades in Laser-Dipole Waves
- 2017
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Ingår i: Physical Review X. - 2160-3308. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- Electromagnetic cascades have the potential to act as a high-energy photon source of unprecedented brightness. Such a source would offer new experimental possibilities in fundamental science, but in the cascade process radiation reaction and rapid electron-positron plasma production seemingly restrict the efficient production of photons to sub-GeV energies. Here, we show how to overcome these energetic restrictions and how to create a directed GeV photon source, with unique capabilities as compared to existing sources. Our new source concept is based on a controlled interplay between the cascade and anomalous radiative trapping. Using specially designed advanced numerical models supported with analytical estimates, we demonstrate that the concept becomes feasible at laser powers of around 7 PW, which is accessible at soon-to-be-available facilities. A higher peak power of 40 PW can provide 10(9) photons with GeV energies in a well-collimated 3-fs beam, achieving peak brilliance 9 x 10(24) ph s(-1) mrad(-2) mm(-2)/0.1%BW.
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| 10. |
- Meyerov, I., et al.
(författare)
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Hybrid CPU + Xeon Phi implementation of the Particle-in-Cell method for plasma simulation
- 2016
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Ingår i: Supercomputing Frontiers and Innovations. - : FSAEIHE South Ural State University (National Research University). - 2313-8734 .- 2409-6008. ; 3:3, s. 5-10
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents experimental results of Particle-in-Cell plasma simulation on a hybrid system with CPUs and Intel Xeon Phi coprocessors. We consider simulation of two relevant laserdriven particle acceleration regimes using the Particle-in-Cell code PICADOR. On a node of a cluster with 2 CPUs and 2 Xeon Phi coprocessors the hybrid CPU + Xeon Phi configuration allows to fully utilize the computational resources of the node. It outperforms both CPU-only and Xeon Phi-only configurations with the speedups between 1.36 x and 1.68 x.
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