400 research outputs found
Mass Spectrometric Determination of the Dissociation Energy of Mn2F6
No full textThe gaseous Mn2F6 molecule has been identified for the first time in the vapor produced by MnF3 vaporization and the MnF3(g) dimerization equilibrium studied by the Knudsen cell mass spectrometry technique in the 884–1015 K temperature range. The experimental vapor pressure data were treated by the second- and third-law procedures, and the enthalpy of Mn2F6(g) dissociation has been determined as: equation image. Thermodynamic functions of gaseous MnF3 were calculated from geometrical and vibrational parameters taken from the literature. For gaseous Mn2F6, they were evaluated by comparison with molecular parameters of Co2F6(g). Copyright © 2002 John Wiley & Sons, Ltd
Radiation damage in the LHCb vertex locator
Get PDFThe LHCb Vertex Locator (VELO) is a silicon strip detector designed to reconstruct charged particle trajectories and vertices produced at the LHCb interaction region. During the first two years of data collection, the 84 VELO sensors have been exposed to a range of fluences up to a maximum value of approximately 45 × 1012 1 MeV neutron equivalent (1 MeV neq). At the operational sensor temperature of approximately −7 °C, the average rate of sensor current increase is 18 μA per fb−1, in excellent agreement with predictions. The silicon effective bandgap has been determined using current versus temperature scan data after irradiation, with an average value of Eg = 1.16±0.03±0.04 eV obtained. The first observation of n+-on-n sensor type inversion at the LHC has been made, occurring at a fluence of around 15 × 1012 of 1 MeV neq. The only n+-on-p sensors in use at the LHC have also been studied. With an initial fluence of approximately 3 × 1012 1 MeV neq, a decrease in the Effective Depletion Voltage (EDV) of around 25 V is observed. Following this initial decrease, the EDV increases at a comparable rate to the type inverted n+-on-n type sensors, with rates of (1.43±0.16) × 10−12 V/ 1 MeV neq and (1.35±0.25) × 10−12 V/ 1 MeV neq measured for n+-on-p and n+-on-n type sensors, respectively. A reduction in the charge collection efficiency due to an unexpected effect involving the second metal layer readout lines is observed
Electronics and readout of a large area silicon detector for LHC
No full textThe purpose of the RD2 project is to evaluate the feasibility of a silicon tracker and/or preshower detector for LHC. Irradiation studies with doses equivalent to those expected at LHC have been performed to determine the behavior of operational parameters such as leakage current, depletion voltage and charge collection during the life of the detector. The development of fast, dense, low power and low cost signal processing electronics is one of the major activities of the collaboration. We describe the first fully functional integrated analog memory chip with asynchronous read and write operations and level 1 trigger capture capabilities. A complete test beam system using this analog memory chip at 66 MHz has been successfully operated with RD2 prototype silicon detectors during various test runs. The flexibility of the electronics and readout have allowed us to easily interface our set-up to other data acquisition systems. Mechanical studies are in progress to design a silicon tracking detector with several million channels that may be operated at low (0-10 °C) temperature, while maintaining the required geometrical precision. Prototype readout boards for such a detector are being developed and simulation studies are being performed to optimize the readout architecture
Actividades polares de la URSS
Get PDFCon motivo de su visita a la URSS para entrevistar al académico Marchuk, el Dr. Taba tuvo la oportunidad de hablar con el Dr. Krutskikh, director del Instituto de Investigación del Ártico y el Antártico de Leningrado, en donde se organiza el trabajo científico de la Unión Soviética en las regiones polares. También tuvo ocasión de escuchar de primera mano el relato de dos graves incidentes ocurridos en la Antártida: del Dr. A.N. Chilingarov, Presidente Adjunto del Comité Estatal de la URSS para la Hidrometeorología y la vigilancia del medio ambiente natural, sobre el rescate del buque de investigación Mikhail Somov; y el del Dr. P.G. Astakhov sobre un incendio ocurrido en la base terrestre remota de Vostok
Контроль дифференциального сопротивления p–n-переходов биполярного транзистора в активном режиме методом импедансной спектроскопии
Get PDFControlling of parameters of manufactured transistors and interoperational controlling during their production are necessary conditions for production of competitive products of electronic industry. Traditionally for controlling of bipolar transistors the direct current measurements and registration of capacity-voltage characteristics are used. Carrying out measurements on alternating current in a wide interval of frequencies (20 Hz–30 MHz) will allow to obtain additional information on parameters of bipolar transistors. The purpose of the work is to show the possibilities of the method of impedance spectroscopy for controlling of differential resistance of p–n-junctions of the bipolar p–n–p-transistor in active mode.The KT814G p–n–p-transistor manufactured by JSC “INTEGRAL” was studied by the method of impedance spectroscopy. The values of differential electrical resistance and capacitance for base–emitter and base–collector p–n-junctions are defi at direct currents in base from 0.8 to 46 µA.The results of the work can be applied to elaboration of techniques of fi checking of discrete bipolar semiconductor devices.Контроль параметров готовых транзисторов и межоперационный контроль при их изготовлении являются необходимыми условия выпуска конкурентоспособных изделий электронной промышленности. Традиционно для контроля биполярных транзисторов используются измерения на постоянном токе и регистрация вольт-фарадных характеристик. Проведение измерений на переменном токе позволит получить дополнительную информацию о параметрах биполярных транзисторов.Цель работы – показать возможности метода импедансной спектроскопии для контроля дифференциального электрического сопротивления p–n-переходов биполярного p–n–p-транзистора в активном режиме.Методом импедансной спектроскопии исследован p–n–p-транзистор КТ814Г производства ОАО «ИНТЕГРАЛ». На переменном токе в интервале частот 20 Hz–30 MHz определены значения дифференциального электрического сопротивления и емкости p–n-переходов база–эмиттера и база–коллектора при постоянных токах базы от 0,8 до 46 µA.Результаты работы могут быть использованы при отработке методик выходного контроля дискретных биполярных полупроводниковых приборов
The Design and function of a radiation tolerant silicon tracker for an LHC experiment
No full textWe present a description of the RD2 design for a silicon tracking detector and discuss its function as an integrated component of an LHC experiment. An advantage of the design is that considerable flexibility is possible in the granularity and radial position of each plane; these parameters are determined by the physics requirements as well as by the radiation environment, engineering and electronics considerations. The simulated performance of the detector is discussed and our experimental investigations of irradiation effects are summarised. The development of an analogue pipe-line and related front-end electronics for the storage and processing of the signals is described. Our work indicates the suitability of silicon as a detector for LHC experiments. © 1993
National Atlas of Arctic: structure and creation approaches
Get PDFOn the instructions of President and Government of the Russian Federation, works for development of National Atlas of Arctic are started in the country. In this article the authors present their ideas from viewpoint of geographers who are well experienced in the field of cartographic works. A structure of future Atlas and lines of approaches to its development are proposed. The totality of experiences of preparation of other geographical atlases in both, the USSR and Russia, as well as the latest achievements of cartography, aerospace sources and GIS-technologies are recommended to be used. The National Atlas of Arctic is understood as a collection of knowledge of spatial-temporal information about geographical, ecological, economic, historical-ethnographic, cultural and social features of the Arctic. This cartographic model of the territory is designed for using in a wide range of scientific, managing, economic, defensive and social activities. A hard copy of the atlas is intended to be used as scientific-reference publication while its electronic version will make it possible to renovate its content and to improve it by means of actualization according to various directions of its practical use 16 sections proposed in a draft of the Atlas content are as follows: introductory, geological structure, relief, mineral resources, environment evolution, climate, land waters, seas, seashores, snow cover, glaciers, permafrost, soils, flora and fauna, state of the environment and the Nature protection, population, economics, and prospects for future. The popular-scientific edition of the Atlas is intended for use by wide circle of readers and also as a textbook for all levels of education. Presentation of material in the Atlas should combine a high scientific level and accessible language. In a popular form it will clarify traditions of careful treatment to the Nature and the nature-protective ethics of religious confessions of local people. Touristic maps will serve as guides for the Arctic with its bio-landscape and cultural diversity. Content of the Atlas should meet requirements of education standard in the field of geography. Ten sections are proposed for this version of the Atlas: introductory, geological structure, relief and resources, climate, permafrost and glaciers, land waters, seas of the Russian part of the Arctic, its flora and fauna, soils, population and economics, and conclusion Scientific and social results of the Atlas publication together with editorial and advertizing effects are demonstrated. Proposals for a format, scales of maps and type of edition are given, and potential participants of this project are indicated
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