| 1. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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| 2. |
- Abate, E., et al.
(författare)
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Combined performance tests before installation of the ATLAS Semiconductor and Transition Radiation Tracking Detectors
- 2008
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 3
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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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| 3. |
- Adriani, O., et al.
(författare)
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Measurements of quasi-trapped electron and positron fluxes with PAMELA
- 2009
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 114, s. A12218-
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents precise measurements of the differential energy spectra of quasi-trapped secondary electrons and positrons and their ratio between 80 MeV and 10 GeV in the near-equatorial region (altitudes between 350 km and 600 km). Latitudinal dependences of the spectra are analyzed in detail. The results were obtained from July until November 2006 onboard the Resurs-DK satellite by the PAMELA spectrometer, a general purpose cosmic ray detector system built around a permanent magnet spectrometer and a silicon-tungsten calorimeter.
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| 4. |
- Asghar, Rizwan, 1974-, et al.
(författare)
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Memory Conflict Analysis and Interleaver Design for Parallel Turbo Decoding Supporting HSPA Evolution
- 2009
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Ingår i: 12th EUROMICRO Conference on Digital System Design. - 9780769537825 ; , s. 699-706
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Konferensbidrag (refereegranskat)abstract
- HSPA evolution has raised the throughput requirements for WCDMA based systems where turbo code has been adapted to perform the error correction. Many parallel turbo decoding architectures have recently been proposed to enhance the channel throughput but the interleaving algorithm used in WCDMA based systems does not freely allows to use them due to high percentage of memory conflicts. This paper provides a comprehensive analysis for reduction of interleaver memory conflicts while generating more than one address in a single clock cycle. It also provides trade-off analysis in terms of area and power efficiency for multiple architectures for different functions involved in the interleaver design. The final architecture supports processing of two parallel SISO blocks and manages the conflicts by applying different approaches like stream misalignment, memory division and small FIFO buffer. The proposed architecture is low cost and consumes 4.3K gates at a frequency of 150MHz. This work also focuses on reduction of pre-processing overheads by introducing the segment based modulo computation, thus providing further relaxation to SISO decoding process.
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| 5. |
- Di, Wu, 1979-, et al.
(författare)
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System Architecture for 3GPP LTE Modem Using a Programmable Baseband Processo
- 2009
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Ingår i: International Symposium on System-on-Chip (SoC 2009).
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Konferensbidrag (refereegranskat)abstract
- 3G evolution towards HSPA and LTE is ongoing which will substantially increase the throughput with higher spectral efficiency. This paper presents the system architecture of an LTE modem based on a programmable baseband processor. The architecture includes a baseband processor that handles processing such as time and frequency synchronization, IFFT/FFT (up to 2048-p), channel estimation and subcarrier demapping. The throughput and latency requirements of a Category 4 User Equipment (CAT4 UE) is met by adding a MIMO symbol detector and a parallel Turbo decoder supporting H-ARQ. This brings both low silicon cost and enough flexibility to support other wireless standards. The complexity demonstrated by the modem shows the practicality and advantage of using programmable baseband processors for a single-chip LTE solution.
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| 6. |
- Eilert, Johan, 1980-, et al.
(författare)
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Complexity Reduction of Matrix Manipulation for Multi-User STBC-MIMO Decoding
- 2007
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Ingår i: IEEE Sarnoff Symmposium,2007. - 9781424424832 ; , s. 1-5
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Konferensbidrag (refereegranskat)abstract
- This paper studies efficient complex valued matrix manipulations for multi-user STBC-MIMO decoding. A novel method called Alamouti blockwise analytical matrix inversion (ABAMI) is proposed for the inversion of large complex matrices that are based on Alamouti sub-blocks. Another method using a variant of Givens rotation is proposed for fast QR decomposition of this kind of matrices. Our solutions significantly reduce the number of operations which makes them more than 4 times faster than several other solutions in the literature. Furthermore, compared to fixed function VLSI implementations, our solution is more flexible and consumes less silicon area because the hardware is programmable and it can be reused for many other operations such as filtering, correlation and FFT/IFFT. Besides the analysis of the general computational complexity based on the number of basic operations, the computational latency is also measured in clock cycles based on the conceptual hardware for real-time matrix manipulations.
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| 7. |
- Eilert, Johan, 1980-, et al.
(författare)
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Efficient Complex Matrix Inversion for MIMO Software Defined Radio
- 2007
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Ingår i: International Symposium on Circuits and Systems, ISCAS,2007. - : IEEE. - 1424409209 ; , s. 2610-2613
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Konferensbidrag (refereegranskat)abstract
- Complex matrix inversion is a very computationally demanding operation in advanced multi-antenna wireless communications. Traditionally, systolic array-based QR decomposition (QRD) is used to invert large matrices. However, the matrices involved in MIMO baseband processing in mobile handsets are generally small which means QRD is not necessarily efficient. In this paper, a new method is proposed using programmable hardware units which not only achieves higher performance but also consumes less silicon area. Furthermore, the hardware can be reused for many other operations such as complex matrix multiplication, filtering, correlation and FFT/IFFT.
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| 8. |
- Eilert, Johan, 1980-, et al.
(författare)
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Implementation of a Programmable Linear MMSE Detector for MIMO-OFDM
- 2008
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Ingår i: IEEE International Conference on Acoustics, Speech and Signal Processing, ICASSP,2008. - : IEEE. - 9781424414833 ; , s. 5396-5399
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Konferensbidrag (refereegranskat)abstract
- This paper presents a linear minimum mean square error (LMMSE) symbol detector for MIMO-OFDM enabled mobile terminals. The detector is implemented using a programmable baseband processor aimed for software-defined radio (SDR). Owing to the dynamic range supplied by the floating-point SIMD datapath, special algorithms can be adopted to reduce the computational latency of detection. The programmable solution not only supports different transmit/receive antenna configurations, but also allows hardware multiplexing to obtain silicon and power efficiency. Compared to several existing fixed-functional solutions, the one proposed in this paper is smaller, more flexible and faster.
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| 9. |
- Eilert, Johan, 1980-, et al.
(författare)
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Real-Time Alamouti STBC Decoding on A Programmable Baseband Processor
- 2008
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Konferensbidrag (refereegranskat)abstract
- This paper presents a space-time block coding decoder for MIMO-OFDM enabled mobile terminals. The decoder is implemented using a programmable baseband processor aimed for software-defined radio (SDR). The dynamic range supplied by the floating-point SIMD datapath allows special algorithms to significantly reduce the computational latency of decoding. The programmable solution not only supports different transmit/receive antenna configuration, but also allows hardware multiplexing to obtain silicon and power efficiency. Compared to several existing fixed-functional ASIC solutions in literature, the one proposed in this paper is by far the smallest, fastest and with more flexibility.
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| 10. |
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