| 1. |
- Abata, E., et al.
(författare)
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Study of energy response and resolution of the ATLAS barrel calorimeter to hadrons of energies from 20 to 350 GeV
- 2010
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier. - 0168-9002 .- 1872-9576 .- 0167-5087. ; 621:1-3, s. 134-150
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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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| 2. |
- Grieser, M., et al.
(författare)
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Storage ring at HIE-ISOLDE
- 2012
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Ingår i: European Physical Journal: Special Topics. - : Springer Science and Business Media LLC. - 1951-6401 .- 1951-6355. ; 207:1, s. 1-117
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Tidskriftsartikel (refereegranskat)abstract
- We propose to install a storage ring at an ISOL-type radioactive beam facility for the first time. Specifically, we intend to setup the heavy-ion, low-energy ring TSR at the HIE-ISOLDE facility in CERN, Geneva. Such a facility will provide a capability for experiments with stored secondary beams that is unique in the world. The envisaged physics programme is rich and varied, spanning from investigations of nuclear ground-state properties and reaction studies of astrophysical relevance, to investigations with highly-charged ions and pure isomeric beams. The TSR might also be employed for removal of isobaric contaminants from stored ion beams and for systematic studies within the neutrino beam programme. In addition to experiments performed using beams recirculating within the ring, cooled beams can also be extracted and exploited by external spectrometers for high-precision measurements. The existing TSR, which is presently in operation at the Max-Planck Institute for Nuclear Physics in Heidelberg, is well-suited and can be employed for this purpose. The physics cases as well as technical details of the existing ring facility and of the beam and infrastructure requirements at HIE-ISOLDE are discussed in the present technical design report.
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| 3. |
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| 4. |
- Zhang, H., et al.
(författare)
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A quantitative robustness evaluation model for optical fiber sensor networks
- 2013
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 31:8, s. 1240-1246
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Tidskriftsartikel (refereegranskat)abstract
- Optical fiber sensor networks (OFSNs) are facing the problem of a lack of systematic evaluation criteria to assess network performance. In this paper, a universal quantitative robustness evaluation model for OFSNs is proposed. The model defines robustness as the mathematical expectation of the monitoring coverage ratio, which has taken into account the performance under all possible network states and the probability of each state. This model is applied to four basic network topologies including line, ring, star and bus topologies, and their mathematical expressions of robustness are derived by analyzing all possible states in detail. Further simulation gives a quantitative comparison among these topologies, proving that the ring and star topologies are optimal for the monitoring of strip-shaped and square regions, respectively. Finally, two influencing factors, the attenuation coefficient and the threshold, are investigated for their impact on the robustness of the network.
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| 5. |
- Jensen, D. Juul, et al.
(författare)
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Importance of local structural variations on recrystallization
- 2013
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Ingår i: Material Science Forum. - : Trans Tech Publications Inc.. - 9783037856888 ; , s. 37-41
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Konferensbidrag (refereegranskat)abstract
- Effects of local variations in the deformation microstructure on subsequent recrystallization are discussed and illustrated by three examples. The three examples consider local variations on different length scales and are: 1. Effects of local variations in the deformation microstructure on the formation of protrusions on migrating boundaries. 2. Effects of an inhomogeneous spatial distribution of second phase particles on growth. 3. Effects of stored energy and orientation variations on recrystallization kinetics.
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| 6. |
- Wang, Shu Min, 1963, et al.
(författare)
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A novel semiconductor compatible path for nano-graphene synthesis using CBr4 precursor and Ga catalyst
- 2014
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322 .- 2045-2322. ; 4
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Tidskriftsartikel (refereegranskat)abstract
- We propose a novel semiconductor compatible path for nano-graphene synthesis using precursors containing C-Br bonding and liquid catalyst. The unique combination of CBr4 as precursor and Ga as catalyst leads to efficient C precipitation at a synthesis temperature of 200 degrees C or lower. The non-wetting nature of liquid Ga on tested substrates limits nano-scale graphene to form on Ga droplets and substrate surfaces at low synthesis temperatures of T = 400 degrees C. Good quality interface nano-graphene is demonstrated and the quality can be further improved by optimization of synthesis conditions and proper selection of substrate type and orientation. The proposed method provides a scalable and transfer-free route to synthesize graphene/semiconductor heterostructures, graphene quantum dots as well as patterned graphene nano-structures at a medium temperature range of 400-700 degrees C suitable for most important elementary and compound semiconductors.
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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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| 8. |
- Zhang, J. Y., et al.
(författare)
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Performance Analysis of Digital Communication Systems Over Composite eta-mu/Gamma Fading Channels
- 2012
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Ingår i: IEEE Transactions on Vehicular Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9545 .- 1939-9359. ; 61:7, s. 3114-3124
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we analyze and evaluate the performance of digital communication systems that operate over a composite fading channel following the eta-mu/gamma distribution. More specifically, new analytical expressions for the channel capacity under different transmission schemes are derived in the form of infinite series. For the special case of integer mu values, simplified closed-form expressions are also obtained. Moreover, we deduce exact tractable formulas for the average bit error rate (BER) of various modulation schemes. In the high-power regime, simplified capacity and BER expressions are provided, revealing the implications of the model parameters on system performance. The relationship of the presented results with previously reported results on generalized-K and K fading channels is also established. We note that the theoretical results presented herein are given in analytical form, which can efficiently be evaluated.
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| 9. |
- Xiong, M., et al.
(författare)
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41.6 Gb/s RZ-DPSK to NRZ-DPSK format conversion in a microring resonator
- 2012
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Ingår i: 2012 17th Opto-Electronics and Communications Conference. ; , s. 891-892
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Konferensbidrag (refereegranskat)abstract
- RZ-DPSK to NRZ-DPSK format conversion in a silicon microring resonator is demonstrated experimentally for the first time at 41.6 Gb/s. The converted signal eye diagrams and bit-error-rate measurements show the good performance of the scheme.
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| 10. |
- Zhang, H., et al.
(författare)
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Application Prospects and Microstructural Features in Laser-Induced Rapidly Solidified High-Entropy Alloys
- 2014
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Ingår i: JOM. - : Springer Science and Business Media LLC. - 1543-1851 .- 1047-4838. ; 66:10, s. 2057-2066
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Forskningsöversikt (refereegranskat)abstract
- Recently, high-entropy alloys (HEAs) have attracted much interest in the materials community, as they offer massive opportunities to observe new phenomena, explore new structure, and develop new materials. Particularly, it is attractive to prepare high-performance HEA coatings by laser-induced rapid solidification, which can be formed on the surface of components and parts in a variety of sizes and shapes with a lower cost in comparison with those bulk material fabrication methods. From the technical point of view, laser-induced rapid solidification could hamper the compositional segregation, improve the solubility in solid-solution phases, and lead to the strengthening effect by the grain refinement. This article reviews the recent work on the typical microstructural features and the mechanical and chemical properties in laser-induced rapidly solidified HEAs, and these data are compared with conventional Co- and Ni-based alloy coatings. The article concludes with suggestions for future research and development in HEAs, from considerations of their characteristic properties.
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