| 1. |
- Schael, S, et al.
(författare)
-
Precision electroweak measurements on the Z resonance
- 2006
-
Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
-
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.
|
|
| 2. |
|
|
| 3. |
- Wirandi, Jenny, et al.
(författare)
-
Human factor validation in an industrial measurement system
- 2008
-
Ingår i: Measurement. - : Elsevier BV. - 0263-2241 .- 1873-412X. ; 41:7, s. 705-718
-
Forskningsöversikt (refereegranskat)abstract
- The object of this study is to determine how people interpret measurement data, which factors influence their interpretation and which do not. This study forms part of an investigation series undertaken at the paper pulp company Södra Cell in Sweden (N = 1200 employees), the investigated parameter being "paper pulp quality". The findings presented in the study are the outcomes of a questionnaire that was repeated four times (n1 = 54, n2 = 53, n3 = 43, n4 = 38), an interview (ni = 32) and regular group discussions that included 10 people (nd = 10) and that took place once a month over a three-year period. In order to quantify the quality of the product - paper pulp - different measurements must be combined. This study reveals that different employees prefer different parameters for the quantification of paper pulp quality. This study furthermore shows that there is a correlation between the employees' choice of parameters and their belonging to a particular pulp mill within the company. We also found that external factors, e.g. the opinion of authorities, affected which parameters were favoured when product quality was determined. Furthermore, the data analysis indicates that there is a correlation between the job-position of employees and the way they interpret measurement data related to product quality. Controllers and operators make similar judgments, with the exception of chemists whose opinions appear to deviate. However, the greatest variation found in the study is related to the individual person - independently of education or physical or psychological condition. The study finally proposes a number of preventive measures to improve the uniformity and reliability of measurements conducted at a process company, the most important of which is improved education of all employees who are in a position to influence product quality. © 2007 Elsevier Ltd. All rights reserved.
|
|
| 4. |
- Wirandi, Jenny, et al.
(författare)
-
Problem of applying modern uncertainty concepts to the measurement of instrument-specific parameters
- 2006
-
Ingår i: IEEE Transactions on Instrumentation and Measurement. - : IEEE. - 0018-9456 .- 1557-9662. ; 55:3, s. 700-705
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a number of problems that occur when applying the Guide to the Expression of Uncertainty in Measurement (GUM) to modern instruments. These instruments are often automatic, which makes it complicated to evaluate the uncertainty components in each measurement step because it is difficult to control and analyze them. Many of these instruments try to quantify instrument-specific parameters, which are difficult to compare with others that have the same dimension but are measured using other techniques. Often, these parameters lack traceable calibration, which may result in a large uncertainty component. This paper also considers the human aspect of the measurement process. © 2006 IEEE.
|
|
| 5. |
- Wirandi, Jenny, et al.
(författare)
-
Uncertainty and traceable calibration - how modern measurement concepts improve product quality in process industry
- 2006
-
Ingår i: Measurement. - : Elsevier BV. - 0263-2241 .- 1873-412X. ; 39:7, s. 612-620
-
Tidskriftsartikel (refereegranskat)abstract
- Research and advanced manufacturing demand high-quality measurement. This requires the statement of measurement uncertainty and the access to traceably calibrated instruments (with traceability to an international reference). Traceability is not obvious, however, for all kinds of industry measurements. Certain industries produce products whose quality control is based on the measurement of fuzzy, complex parameters, "attributes". Many of these parameters are nowadays measured by sophisticated instruments. They are often automated and can perform an increased number of measurements during the day. Traceability is often a problem for this type of instruments. There are solutions to solve their lack of traceability, for example round-robin rings, but they must be handled with care. Quantifying measurement uncertainty may also become problematic, since the establishment of an uncertainty budget is difficult for automated or semi-automated instruments. If traceability is lacking, an important task will be to evaluate the uncertainty of the repeatability of the instrument since this will be an important part of the uncertainty budget. This article discusses problems and solutions, using the attributes paper pulp quality and smell as illustrations. © 2006 Elsevier Ltd. All rights reserved.
|
|
