1,722,792 research outputs found
The CMS silicon tracker
No full textThis paper describes the Silicon microstrip Tracker of the CMS experiment at LHC. It consists of a barrel part with 5 layers and two endcaps with 10 disks each. About 10000 single-sided equivalent modules have to be built, each one carrying two daisy-chained silicon detectors and their front-end electronics. Back-to-back modules are used to read-out the radial coordinate. The tracker will be operated in an environment kept at a temperature of T = -10 degreesC to minimize the Si sensors radiation damage. Heavily irradiated detectors will be safely operated due to the high-voltage capability of the sensors. Full-size mechanical prototypes have been built to check the system aspects before starting the construction
Test results of heavily irradiated Si detectors
No full textA large use of silicon microstrip detectors is foreseen for the intermediate part of the CMS tracker. A specific research and development program has been carried out with the aim of finding design layouts and technological solutions for allowing silicon microstrip detectors to be reliably used on a high radiation level environment. As a result of this work single sided, AC-coupled, polysilicon biased, 300 mu m thick, p(+) on n substrate detectors were chosen. Irradiation tests have been performed on prototypes up to fluence 2 x 10(14) n/cm(2). The detector performances do not significantly change if the detectors are biased well above the depletion voltage. S/N is reduced by less than 20%, still enough to insure a good efficiency and space resolution. Multiguard structures has been developed in order to reach high voltage operation (above 500 V)
The CMS silicon microstrip detectors: research and development
No full textA large quantity of silicon microstrip detectors is foreseen to be used as part of the CMS tracker. A specific research and development program has been carried out with the aim of defining layouts and technological solutions suitable for the use of silicon detectors in high radiation environment. Results presented here summarise this work on many research areas such as techniques for device manufacturing, pre- and post-irradiation electrical characterization, silicon bulk defects analysis and simulations, system performance analytical calculations and simulations and test beam analysis. As a result of this work we have chosen to use single-sided, AC-coupled, poly silicon biased, 300 mu m thick, p(+) on n substrate detectors. We feel confident that these devices will match the required performances for the CMS tracker provided they can be operated at bias voltages as high as 500 V. Such high-voltage devices have been succesfully manufactured and we are now concentrating our efforts in enhancing yield and reliability
Developments for radiation hard silicon detectors by defect engineering - results by the CERN RD48 (ROSE) Collaboration
No full textThis report summarises the final results obtained by the RD48 collaboration. The emphasis is on the more practical
aspects directly relevant for LHC applications. The report is based on the comprehensive survey given in the 1999 status
report (RD48 3rd Status Report, CERN/LHCC 2000-009, December 1999), a recent conference report (Lindstr .om et al.
(RD48), and some latest experimental results. Additional data have been reported in the last ROSE workshop
(5th ROSE workshop, CERN, CERN/LEB 2000-005). A compilation of all RD48 internal reports and a full
publication list can be found on the RD48 homepage (http://cern.ch/RD48/). The success of the oxygen enrichment of
FZ-silicon as a highly powerful defect engineering technique and its optimisation with various commercial manufacturers
are reported. The focus is on the changes of the effective doping concentration (depletion voltage). The RD48 model for
the dependence of radiation effects on fluence, temperature and operational time is verified; projections to operational
scenarios for main LHC experiments demonstrate vital benefits. Progress in the microscopic understanding of damage
effects as well as the application of defect kinetics models and device modelling for the prediction of the macroscopic
behaviour has also been achieved but will not be covered in detail
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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