| 1. |
- Abelev, B., et al.
(författare)
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Technical Design Report for the Upgrade of the ALICE Inner Tracking System
- 2014
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 41:8
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Tidskriftsartikel (refereegranskat)abstract
- LICE (A Large Ion Collider Experiment) is studying the physics of strongly interacting matter, and in particular the properties of the Quark–Gluon Plasma (QGP), using proton–proton, proton–nucleus and nucleus–nucleus collisions at the CERN LHC (Large Hadron Collider). The ALICE Collaboration is preparing a major upgrade of the experimental apparatus, planned for installation in the second long LHC shutdown in the years 2018–2019. A key element of the ALICE upgrade is the construction of a new, ultra-light, high-resolution Inner Tracking System (ITS) based on monolithic CMOS pixel detectors. The primary focus of the ITS upgrade is on improving the performance for detection of heavy-flavour hadrons, and of thermal photons and low-mass di-electrons emitted by the QGP. With respect to the current detector, the new Inner Tracking System will significantly enhance the determination of the distance of closest approach to the primary vertex, the tracking efficiency at low transverse momenta, and the read-out rate capabilities. This will be obtained by seven concentric detector layers based on a 50 μm thick CMOS pixel sensor with a pixel pitch of about 30×30 μm2. This document, submitted to the LHCC (LHC experiments Committee) in September 2013, presents the design goals, a summary of the R&D activities, with focus on the technical implementation of the main detector components, and the projected detector and physics performance.
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| 2. |
- Abelev, B., et al.
(författare)
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Upgrade of the ALICE Experiment Letter Of Intent
- 2014
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Ingår i: Journal of Physics G: Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 41:8
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Tidskriftsartikel (refereegranskat)abstract
- ALICE (A Large Ion Collider Experiment) is studying the physics of strongly interacting matter, and in particular the properties of the Quark–Gluon Plasma (QGP), using proton–proton, proton–nucleus and nucleus–nucleus collisions at the CERN LHC (Large Hadron Collider). The ALICE Collaboration is preparing a major upgrade of the experimental apparatus, planned for installation in the second long LHC shutdown in the years 2018–2019. These plans are presented in the ALICE Upgrade Letter of Intent, submitted to the LHCC (LHC experiments Committee) in September 2012. In order to fully exploit the physics reach of the LHC in this field, high-precision measurements of the heavy-flavour production, quarkonia, direct real and virtual photons, and jets are necessary. This will be achieved by an increase of the LHC Pb–Pb instant luminosity up to 6×1027 cm−2s−1 and running the ALICE detector with the continuous readout at the 50 kHz event rate. The physics performance accessible with the upgraded detector, together with the main detector modifications, are presented.
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| 3. |
- Aamodt, K., et al.
(författare)
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The ALICE experiment at the CERN LHC
- 2008
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 3:S08002
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Forskningsöversikt (refereegranskat)abstract
- ALICE (A Large Ion Collider Experiment) is a general-purpose, heavy-ion detector at the CERN LHC which focuses on QCD, the strong-interaction sector of the Standard Model. It is designed to address the physics of strongly interacting matter and the quark-gluon plasma at extreme values of energy density and temperature in nucleus-nucleus collisions. Besides running with Pb ions, the physics programme includes collisions with lighter ions, lower energy running and dedicated proton-nucleus runs. ALICE will also take data with proton beams at the top LHC energy to collect reference data for the heavy-ion programme and to address several QCD topics for which ALICE is complementary to the other LHC detectors. The ALICE detector has been built by a collaboration including currently over 1000 physicists and engineers from 105 Institutes in 30 countries, Its overall dimensions are 16 x 16 x 26 m(3) with a total weight of approximately 10 000 t. The experiment consists of 18 different detector systems each with its own specific technology choice and design constraints, driven both by the physics requirements and the experimental conditions expected at LHC. The most stringent design constraint is to cope with the extreme particle multiplicity anticipated in central Pb-Pb collisions. The different subsystems were optimized to provide high-momentum resolution as well as excellent Particle Identification (PID) over a broad range in momentum, up to the highest multiplicities predicted for LHC. This will allow for comprehensive studies of hadrons, electrons, muons, and photons produced in the collision of heavy nuclei. Most detector systems are scheduled to be installed and ready for data taking by mid-2008 when the LHC is scheduled to start operation, with the exception of parts of the Photon Spectrometer (PHOS), Transition Radiation Detector (TRD) and Electro Magnetic Calorimeter (EMCal). These detectors will be completed for the high-luminosity ion run expected in 2010. This paper describes in detail the detector components as installed for the first data taking in the summer of 2008.
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| 4. |
- Bécoulet, A., et al.
(författare)
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Science and technology research and development in support to ITER and the Broader Approach at CEA
- 2013
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10
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Tidskriftsartikel (refereegranskat)abstract
- In parallel to the direct contribution to the procurement phase of ITER and Broader Approach, CEA has initiated research & development programmes, accompanied by experiments together with a significant modelling effort, aimed at ensuring robust operation, plasma performance, as well as mitigating the risks of the procurement phase. This overview reports the latest progress in both fusion science and technology including many areas, namely the mitigation of superconducting magnet quenches, disruption-generated runaway electrons, edge-localized modes (ELMs), the development of imaging surveillance, and heating and current drive systems for steady-state operation. The WEST (W Environment for Steady-state Tokamaks) project, turning Tore Supra into an actively cooled W-divertor platform open to the ITER partners and industries, is presented.
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| 5. |
- Alme, J., et al.
(författare)
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The ALICE TPC, a large 3-dimensional tracking device with fast readout for ultra-high multiplicity events
- 2010
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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. ; 622:1, s. 316-367
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Tidskriftsartikel (refereegranskat)abstract
- The design, construction, and commissioning of the ALICE Time-Projection Chamber (TPC) is described. It is the main device for pattern recognition, tracking, and identification of charged particles in the ALICE experiment at the CERN LHC. The TPC is cylindrical in shape with a volume close to 90 m(3) and is operated in a 0.5T solenoidal magnetic field parallel to its axis. In this paper we describe in detail the design considerations for this detector for operation in the extreme multiplicity environment of central Pb-Pb collisions at LHC energy. The implementation of the resulting requirements into hardware (field cage, read-out chambers, electronics), infrastructure (gas and cooling system, laser-calibration system), and software led to many technical innovations which are described along with a presentation of all the major components of the detector, as currently realized. We also report on the performance achieved after completion of the first round of stand-alone calibration runs and demonstrate results close to those specified in the TPC Technical Design Report. (C) 2010 CERN for the benefit of the ALICE collaboration. Published by Elsevier B.V. All rights reserved.
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| 6. |
- Kopp, C., et al.
(författare)
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Very compact FTTH Diplexer design using advanced wafer level fabrication methods
- 2008
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Ingår i: MICRO-OPTICS 2008. - Strasbourg : SPIE.
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Konferensbidrag (refereegranskat)abstract
- FTTH networks require implementing a diplexer at each user termination. According to most of the standards, this diplexer detects a download signal beam at 1.49ÎŒm and emits an upload signal beam at 1.31ÎŒm on the same single mode fibre. Both signals exhibit datarate speed below 2.5Gbps. Today, most of the diplexers are obtained by actively aligning a set of individual optoelectronic components and micro-optics. However, new manufacturing solutions satisfying very low cost and mass production capability requirements of this market would help to speed the massive spreading of this technology. In this paper, we present an original packaging design to manufacture Diplexer Optical Sub-Assembly for FTTH application. A dual photodiode is stacked over a VCSEL and detects both the download signal beam at 1.49ÎŒm passing through the laser and one part of the upload signal beam at 1.31ÎŒm for monitoring. To satisfy this approach, an innovative VCSEL has been designed to have a very high transmission at 1.49ÎŒm. All these components are mounted on a very small circuit board on glass including also integrated circuits such as transimpedance amplifier. So, the device combines advanced optoelectronic components and highly integrated Multi-Chip-Module on glass approach using collective wafer-level assembling technologies. For the single mode fibre optical coupling, active and passive alignment solutions are considered.
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| 7. |
- Gustafsson, Oscar, et al.
(författare)
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Long-wavelength infrared quantum-dot based interband photodetectors
- 2011
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Ingår i: Infrared physics & technology. - : Elsevier BV. - 1350-4495 .- 1879-0275. ; 54:3, s. 287-291
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Tidskriftsartikel (refereegranskat)abstract
- We report on the design and fabrication of (Al)GaAs(Sb)/InAs tensile strained quantum-dot (QD) based detector material for thermal infrared imaging applications in the long-wavelength infrared (LWIR) regime. The detection is based on transitions between confined dot states and continuum states in a type-II band lineup, and we therefore refer to it as a dot-to-bulk (D2B) infrared photodetector with expected benefits including long carrier lifetime due to the type-II band alignment, suppressed Shockley-Read-Hall generation-recombination due to the relatively large-bandgap matrix material, inhibited Auger recombination processes due to the tensile strain and epitaxial simplicity. Metal-organic vapor-phase epitaxy was used to grow multiple (Al)GaAs(Sb) QD layers on InAs substrates at different QD nominal thicknesses, compositions, doping conditions and multilayer periods, and the material was characterized using atomic force and transmission electron microscopy, and Fourier-transform infrared absorption spectroscopy. Dot densities up to 1 x 10(11) cm(-2), 1 x 10(12) cm(-2) and 3 x 10(10) cm(-2) were measured for GaAs, AlGaAs and GaAsSb QDs, respectively. Strong absorption in GaAs, AlGaAs and GaAsSb multilayer QD samples was observed in the wavelength range 6-12 mu m. From the wavelength shift in the spectral absorption for samples with varying QD thickness and composition it is believed that the absorption is due to an intra- valance band transition. From this it is possible to estimate the type-II inter-band transition wavelength, thereby suggesting that (Al)GaAs(Sb) QD/InAs heterostructures are suitable candidates for LWIR detection and imaging.
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| 16. |
- Junique, Stephane, et al.
(författare)
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A Modulating retro-reflector for free-space optical communication
- 2006
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Ingår i: IEEE Photonics Technology Letters. - 1041-1135 .- 1941-0174. ; 18:1, s. 85-87
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Tidskriftsartikel (refereegranskat)abstract
- We present modeling of a modulating retro-reflector for free-space optical communication, composed of a reflective resonant-cavity modulator and a corner cube. Although resonant-cavity modulators are sensitive to the angle of incidence of the light beam, we show that with the right geometrical arrangement, the field of view can be more than ten-fold that of the modulator. The modeling is validated by experimental data using a corner cube and a 14 x 14 mm(2) multiple quantum-well modulator.
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| 17. |
- Junique, Stephan, et al.
(författare)
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GaAs-based multiple-quantum-well spatial light modulators fabricated by a wafer-scale process
- 2005
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 44:9, s. 1635-1641
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Tidskriftsartikel (refereegranskat)abstract
- The design, fabrication, and characterization of large, two-dimensional multiple-quantum-well modulator arrays are presented. Such arrays present a speed advantage compared with competing technologies such as liquid crystals and micromirrors, which are intrinsically limited to the kilohertz range. We discuss the design compromises to reach high-contrast, low-voltage swing optical structures compatible with complementary metal-oxide semiconductor-based integrated circuits and present experimental results. Contrast ratio of 5:1 (limited by the fill factor), variations in uniformity below 1 nm, and frame rates in excess of 10 kHz are demonstrated. Technology maturity for volume production is also discussed.
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| 18. |
- Junique, Stephane, et al.
(författare)
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Large–area, three–state, binary amplitude and binary phase vertical–cavity multiple quantum well electroabsorption modulator
- 2007
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Ingår i: Optics Express. - 1094-4087. ; 15:14, s. 8566-8575
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Tidskriftsartikel (refereegranskat)abstract
- We present the design and characterization of a large optical modulator array based on GaAs multiple quantum wells for amplitude and phase modulation. The device shows two high-reflectance states with a phase difference close to 180 degrees for use as a binary phase modulator. It also shows a third, low-reflectance state for use as an amplitude modulator. It is segmented into 64 pixels in a single row, giving an active area of 2mm x 5mm. We discuss the device performance as a ternary binary amplitude and binary phase modulator, including contrast ratio and uniformity, and show that a voltage swing of only 5V is needed to drive it.
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| 19. |
- Wang, Qin, et al.
(författare)
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1550 nm transmissive/reflective surface-normal electroabsorption modulator arrays
- 2006
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Ingår i: Electronics Letters. - : Institution of Engineering and Technology (IET). - 0013-5194 .- 1350-911X. ; 42:1, s. 47-48
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Tidskriftsartikel (refereegranskat)abstract
- Arrays of surface-normal 1550 nm transmissive/reflective dual-function electroabsorption modulators based oil InGaAs/InAlAs coupled quantum wells are investigated for free-space and optical fibre communications. The modulators can readily be switched between transmissive or reflective mode by using a removable Au mirror, which provides flexibility in the optical system configuration for different applications. The modulators exhibit contrast ratio of 2:1 at 3 V driving bias and contrast ratio of 2:1 over 30 nm bandwidth at 6 V. The maximum contrast ratio of 4:1 is achieved at a 12 V driving voltage.
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| 20. |
- Wang, Qin, et al.
(författare)
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Arrays of vertical-cavity electroabsorption modulators for parallel signal processing
- 2005
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Ingår i: Optics Express. - 1094-4087. ; 13:9, s. 3323-3330
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Tidskriftsartikel (refereegranskat)abstract
- Vertical-cavity multiple quantum well electroabsorption modulators (EAM) offer gigahertz modulation speeds, insensitivity to light polarisation and can be integrated into large arrays. They are therefore good candidates for efficient parallel signal processing architectures. We present high-performance 2 x 128 and 2 x 64 EAM arrays that were fabricated at 4" wafer-scale by using optimised fabrication and hybridisation processes. The arrays exhibit contrast ratios of 20: 1 with a voltage swing of 1 V, a maximum contrast ratio of 335: 1 for a 10 V bias and a modulation frequency in excess of 15 MHz.
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| 21. |
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| 22. |
- Wang, Q., et al.
(författare)
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Wide-aperture GaAs/AlGaAs multiple quantum well electro-optic modulators
- 2002
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Ingår i: Proceedings of SPIE, the International Society for Optical Engineering. - : SPIE. - 0277-786X .- 1996-756X. ; 4947, s. 59-67
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present design and fabrication methods for surface normal monolithic amplitude modulators with an aperture up to 14 × 14 mm2, a contrast ratio of 6:1 and for low driving voltages (=8 V). The modulators consist of undoped GaAs/AlGaAs quantum wells embedded in a Fabry-Perot (FP) resonance cavity grown by MOVPE. To improve the device performance the FP cavity, the period and thickness of the quantum well and doping concentration were optimised. Also, the dimension of the modulator were varied from 0.5 × 0.5 to 14 × 14 mm2. The results show that the yield of the modulators increases significantly when decreasing the size of the modulators. To remedy the low yield issue for wide aperture modulator, a pixelated approach was used to divide the mono pixel in a monolithic modulator into several pixels, for example from 4 to 48. The modulation speed of the modulators with different dimensions was characterised by electro-optic (EO) response measurements. The temporal optical response of the large modulators was satisfactory up to the order of MHz modulation frequency where the RC constant limited the performance. A few of the modulators with wide apertures are to be assembled into an optical link system for free-space communication.
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