| 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. |
- Vavra, I, et al.
(författare)
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The influence of thermal processing on structural and electrical properties of WxSi1−x/Si multilayers
- 1994
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Ingår i: Nuclear Instruments & Methods in Physics Research. Section A: Accelerators, Spectrometers, Detectors, and Associated Equipment. - 0168-9002. ; 350:1-2, s. 379-390
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Tidskriftsartikel (refereegranskat)abstract
- Thermal stability of WxSi1−x/Si multilayers (MLs) with x varying from 1 to 0.11 is studied by TEM and LAXS. The structure of the prepared samples is amorphous. Doping of W sublayers with silicon affects the interdiffusion process as well as the crystallization in these sublayers. We investigated these two processes (which have a detrimental influence on e.g. X-ray mirror stability) by annealing our samples at 400°C for 40 min. The structural changes were monitored by resistance measurement in the temperature range of 1.5–300 K. A correlation between structural and electrical characteristics was found, which is based on the comparison between three different R(T) curves. It is shown in our paper that the R(T) curve of a ML lies between the R(T) curves of two extreme types of single layers. The first single layer is the analogue of a fully intermixed ML and the second one represents a parallel connection of all conductive sublayers. Thus, a simple resistance measurement can give additional information about the quality of interfaces. We claim that in MLs with ultrathin sublayers the reported highest thermal stability of the amorphous mixture W0.72Si0.28 cannot be utilized because interdiffusion dominates over crystallization so that the superlattice structure is not retained.
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| 3. |
- Dobrocka, E, et al.
(författare)
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Simulation of electron diffraction patterns from III–V alloys with CuPt ordering : Effect of clusters and antiphase boundaries
- 2001
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 89, s. 2653-2664
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Tidskriftsartikel (refereegranskat)abstract
- A method for the simulation of electron diffraction patterns from partially ordered semiconductor compounds with CuPt-type ordering is proposed. The simulation procedure is based on the generation of two-dimensional model structures containing different types of imperfections. The defects are randomly dispersed in the structure and they are characterized by statistical parameters (density, average size, shape, etc.). Performing the intensity calculations for electron diffraction, the influence of the selected types of defects on the diffuse scattering in the transmission electron microscopy (TEM) diffraction patterns can be analyzed and the correlation between the statistical parameters describing the defects and the fine structure of the diffuse scattering can be established. By means of this method the influence of the plate-like clusters and of the antiphase boundaries (APBs) on the TEM diffraction pattern is analyzed. It is shown that the slope of the diffuse streaks around the ordering diffraction spots is determined by the mean orientation of the cluster boundaries irrespective of the type of clusters. The role of the fine structure of the inclined APBs in the formation of the diffraction patterns is established. (C) 2001 American Institute of Physics.
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| 4. |
- Vavra, I, et al.
(författare)
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Electron-beam mixing of W1 - xSix Si multilayers
- 1995
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Ingår i: Vacuum. - 0042-207X. ; 46:8-10, s. 1063-1064
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Tidskriftsartikel (refereegranskat)abstract
- The high energy electron beam was used for the local amorphisation of metallic multilayer. The observed effect is proposed for the application in nanometer-scale technology.
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| 5. |
- Vavra, I, et al.
(författare)
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Structural and electrical properties of superconducting Nb/Si multilayers
- 1998
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Ingår i: Vacuum. - 0042-207X. ; 50:1-2, s. 31-33
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Tidskriftsartikel (refereegranskat)abstract
- We have found the deposition technology at which the interface roughness of Nb/Si multilayer is strongly correlated and decreases with deposited layer number. On the basis of our Nb/Si multilayer we succeeded to prepare ten-fold stacked Josephson junction (JJ). Basic electric properties of stacked JJ are presented.
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