5,451 research outputs found

    Prospects for CP violation measurements with ATLAS and CMS

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    Very high LHC luminosity will result in ~10^13 b-particles produced per year allowing general purpose detectors ATLAS and CMS to contribute to the exploration of phenomena in B physics. A review of simulation studies made by ATLAS and CMS B-physics groups is given. The expected numbers of reconstructed events, sensitivities to CP violating parameters, the x_s measurements, and possibilities to observe very rare B-decays are discussed

    Position Dependence of Charge Collection in Prototype Sensors for the CMS Pixel Detector

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    This paper reports on the sensor R&D activity for the CMS pixel detector. Devices featuring several design and technology options have been irradiated up to a proton fluencec of 1E15 n_eq/cm**2 at the CERN PS. Afterward they were bump bonded to unirradiated readout chips and tested using high energy pions in the H2 beam line of the CERN SPS. The readout chip allows a non zero suppressed full analogue readout and therefore a good characterization of the sensors in terms of noise and charge collection properties. The position dependence of signal is presented and the differences between the two sensor options are discussed.Comment: Contribution to the IEEE-NSS Oct. 2003, Portland, OR, USA, submitted to IEEE-TNS 7 pages, 8 figures, 1 table. Revised, title change

    A double junction model of irradiated silicon pixel sensors for LHC

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    In this paper we discuss the measurement of charge collection in irradiated silicon pixel sensors and the comparison with a detailed simulation. The simulation implements a model of radiation damage by including two defect levels with opposite charge states and trapping of charge carriers. The modeling proves that a doubly peaked electric field generated by the two defect levels is necessary to describe the data and excludes a description based on acceptor defects uniformly distributed across the sensor bulk. In addition, the dependence of trap concentrations upon fluence is established by comparing the measured and simulated profiles at several fluences and bias voltages.Comment: Talk presented at the 10th European Symposium on Semiconductor Detectors, June 12-16 2005, Wildbad Kreuth, Germany. 9 pages, 4 figure

    Extraction of electric field in heavily irradiated silicon pixel sensors

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    A new method for the extraction of the electric field in the bulk of heavily irradiated silicon pixel sensors is presented. It is based on the measurement of the Lorentz deflection and mobility of electrons as a function of depth. The measurements were made at the CERN H2 beam line, with the beam at a shallow angle with respect to the pixel sensor surface. The extracted electric field is used to simulate the charge collection and the Lorentz deflection in the pixel sensor. The simulated charge collection and the Lorentz deflection is in good agreement with the measurements both for non-irradiated and irradiated up to 1E15 neq/cm2 sensors.Comment: 6 pages, 11 figures, presented at the 13th International Workshop on Vertex Detectors for High Energy Physics, September 13-18, 2004, Menaggio-Como, Italy. Submitted to Nucl. Instr. Meth.

    Observation, modeling, and temperature dependence of doubly peaked electric fields in irradiated silicon pixel sensors

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    We show that doubly peaked electric fields are necessary to describe grazing-angle charge collection measurements of irradiated silicon pixel sensors. A model of irradiated silicon based upon two defect levels with opposite charge states and the trapping of charge carriers can be tuned to produce a good description of the measured charge collection profiles in the fluence range from 0.5x10^{14} Neq/cm^2 to 5.9x10^{14} Neq/cm^2. The model correctly predicts the variation in the profiles as the temperature is changed from -10C to -25C. The measured charge collection profiles are inconsistent with the linearly-varying electric fields predicted by the usual description based upon a uniform effective doping density. This observation calls into question the practice of using effective doping densities to characterize irradiated silicon.Comment: 8 pages, LaTeX document, 10 figures. Presented at Pixel 2005 Workshop, Bonn, Sept 2005. Small cosmetic revisions in response to referee comments and to fix broken reference link

    Tests of silicon sensors for the CMS pixel detector

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    The tracking system of the CMS experiment, currently under construction at the Large Hadron Collider (LHC) at CERN (Geneva, Switzerland), will include a silicon pixel detector providing three spacial measurements in its final configuration for tracks produced in high energy pp collisions. In this paper we present the results of test beam measurements performed at CERN on irradiated silicon pixel sensors. Lorentz angle and charge collection efficiency were measured for two sensor designs and at various bias voltages.Comment: Talk presented at 6th International Conference on Large Scale Applications and Radiation Hardness of Semiconductor Detectors, September 29-October 1, 2003, Firenze, Italy. Proceedings will be published in Nuclear Instr. & Methods in Phys. Research, Section

    Success Factors of Small and Medium-Sized International Enterprises in the Chinese Market from the Perspective of Polish Direct Investment (Cultural Approach)

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    Globalization has resulted in increasing transfer of firms operations, regardless of their size, to other countries. The recent dynamic emergence of China in the global economy, connecting with the vast inflows of foreign direct investment in their territory and common adjustments problems of many Western companies, has resulted in growing interest for best suitable business practices to this culturally and socially different environment. In this article, the key factors critical to the success of international companies in this region are introduced, with particular consideration to indigenous cultural elements and specific operation requirements of small and medium-sized enterprises in Business-to-Business sectors. The presented information are based on the broad literature review, five years of direct observation and thirty eight interviews conducted with Polish managers directly residing in China. In addition, some practical recommendations for managers and further research are given.Globalizacja wymusza na firmach, niezale┼╝nie od ich wielko┼Ťci, coraz cz─Östsze przenoszenie operacji do innych kraj├│w. Dynamiczne pojawienie si─Ö Chin w ┼Ťwiatowej gospodarce i szeroki nap┼é;yw zagranicznych inwestycji bezpo┼Ťrednich na ich teren oraz problemy adaptacyjne wielu zachodnich przedsi─Öbiorstw, spowodowa┼é;y zainteresowanie najlepszymi praktykami biznesowymi dostosowanymi do tego odmiennego kulturowo i spo┼é;ecznie otocznia. W artykule zaprezentowane zosta┼é;y najwa┼╝niejsze czynnik maj─ůce wp┼é;yw na osi─ůgni─Öcie sukcesu przez firmy mi─Ödzynarodowe na tym obszarze, ze szczeg├│lnym uwzgl─Ödnieniem aspekt├│w kulturowych i specyfiki dzia┼é;ania ma┼é;ych i ┼Ťrednich podmiot├│w na rynkach B2B. Prezentowane informacje s─ů oparte na przegl─ůdzie literatury, pi─Öcioletnich obserwacjach bezpo┼Ťrednich oraz trzydziestu o┼Ťmiu wywiadach przeprowadzonych z menad┼╝erami polskich przedsi─Öbiorstw odpowiedzialnymi za operacje w Chinach. Dodatkowo wskazano kilka praktycznych rekomendacji menad┼╝erskich oraz mo┼╝liwo┼Ťci dalszych bada┼ä

    Simulation of Heavily Irradiated Silicon Pixel Detectors

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    We show that doubly peaked electric fields are necessary to describe grazing-angle charge collection measurements of irradiated silicon pixel sensors. A model of irradiated silicon based upon two defect levels with opposite charge states and the trapping of charge carriers can be tuned to produce a good description of the measured charge collection profiles in the fluence range from 0.5x10^{14} Neq/cm^2 to 5.9x10^{14} Neq/cm^2. The model correctly predicts the variation in the profiles as the temperature is changed from -10C to -25C. The measured charge collection profiles are inconsistent with the linearly-varying electric fields predicted by the usual description based upon a uniform effective doping density. This observation calls into question the practice of using effective doping densities to characterize irradiated silicon. The model is now being used to calibrate pixel hit reconstruction algorithms for CMS.Comment: Invited talk at International Symposium on the Development of Detectors for Particle, AstroParticle and Synchrtron Radiation Experiments, Stanford Ca (SNIC06) 8 pages, LaTeX, 11 eps figure

    Fluence Dependence of Charge Collection of irradiated Pixel Sensors

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    The barrel region of the CMS pixel detector will be equipped with ``n-in-n'' type silicon sensors. They are processed on DOFZ material, use the moderated p-spray technique and feature a bias grid. The latter leads to a small fraction of the pixel area to be less sensitive to particles. In order to quantify this inefficiency prototype pixel sensors irradiated to particle fluences between 4.7├Ś10134.7\times 10^{13} and 2.6\times 10^{15} \Neq have been bump bonded to un-irradiated readout chips and tested using high energy pions at the H2 beam line of the CERN SPS. The readout chip allows a non zero suppressed analogue readout and is therefore well suited to measure the charge collection properties of the sensors. In this paper we discuss the fluence dependence of the collected signal and the particle detection efficiency. Further the position dependence of the efficiency is investigated.Comment: 11 Pages, Presented at the 5th Int. Conf. on Radiation Effects on Semiconductor Materials Detectors and Devices, October 10-13, 2004 in Florence, Italy, v3: more typos corrected, minor changes required by the refere
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