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Investigation of Ageing effects and Image stability in Hybrid Photon Pixel detectors at the LHCb experiment CERN / Undersökning av åldringseffekter och bildstabilitet i hybrida foton-pixel-detektorer vid LHCb experimentet CERNMollén, Albert January 2010 (has links)
<p>The world’s largest particle accelerator, Large Hadron Collider, located at CERN outside Geneva performed its first proton-proton collisions in November 2009. One of the four main experiments is LHCb, studying rare decays of hadrons containing the beauty quark. An essential part of the particle identification in LHCb is made by the two Ring Imaging Cherenkov detectors. These detectors use pixel Hybrid Photon Detectors for detection and imaging of Cherenkov rings. This paper reports on measurements carried out on the Hybrid Photon Detectors, including a discussion of the results. In particular, ageing effect and image stability are studied. A fraction of the photon detectors show a degradation in performance within these fields.</p> / <p>Världens största partikelaccelerator, LHC, belägen vid CERN utanför Genève utförde sina första proton-proton kollisioner i November 2009. Ett av de fyra huvudexperimenten är LHCb, som studerar sällsynta sönderfall av hadroner innehållande <em>b</em> kvarken. En viktig del av partikelidentifikationen i LHCb görs av de två RICH detektorerna. Dessa använder hybrida fotondetektorer för detektering och avbildning av Cherenkov ringar. Denna rapport handlar om mätningar utförda på dessa hybrida fotondetektorer, med en diskussion av resultaten. I synnerhet studeras åldringseffekter och bildstabilitet. En andel av fotondetektorerna visar en degradering i prestanda inom dessa områden.</p>
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Visual Stimuli for Charity : A field experiment about recycling and charitable givingMarklund, Victor January 2010 (has links)
<p>Never before has the interest for charity been greater. At this writing, U.S. charities have collected nearly one billion U.S. dollars (!) only in the aid for the disaster victims in Haiti.But can you get people to give even more? Are there yet unexplored market in which charitable organizations still have growth potential? Traditional economic theory which is based in individuals' rational behavior and self-utility maximization has a hard time to explain the phenomenon of charitable donations. But relatively new research can possibly connect the theory and the phenomenon through the theorem of warm-glow in why people actually donate money anonymously and indirectly to people they never met or will ever know who made the donation. This thesis will examine whether or not a small change in the environment could influence individuals to donate more money and / or more frequently. The study was conducted as a field experiment at an ICA store deposit station where people are faced with the choice to donate their deposit to the Swedish Red Cross instead of getting a voucher for themselves. The obtained results shows a statistically significant difference between the donation of the pledge of over 13 percentage more in the presence of a visual stimulus, more specifically a picture of a poor boy drinking clean water from a tap. That results in a doubling in nominal amounts of donations for the charity. Moreover, I find that people who already before the experiment are sympathetic to donating the pledge do so to a greater extent than people who were not. Neither sex nor age seemed to affect the results in any way.</p>
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Visual Stimuli for Charity : A field experiment about recycling and charitable givingMarklund, Victor January 2010 (has links)
Never before has the interest for charity been greater. At this writing, U.S. charities have collected nearly one billion U.S. dollars (!) only in the aid for the disaster victims in Haiti.But can you get people to give even more? Are there yet unexplored market in which charitable organizations still have growth potential? Traditional economic theory which is based in individuals' rational behavior and self-utility maximization has a hard time to explain the phenomenon of charitable donations. But relatively new research can possibly connect the theory and the phenomenon through the theorem of warm-glow in why people actually donate money anonymously and indirectly to people they never met or will ever know who made the donation. This thesis will examine whether or not a small change in the environment could influence individuals to donate more money and / or more frequently. The study was conducted as a field experiment at an ICA store deposit station where people are faced with the choice to donate their deposit to the Swedish Red Cross instead of getting a voucher for themselves. The obtained results shows a statistically significant difference between the donation of the pledge of over 13 percentage more in the presence of a visual stimulus, more specifically a picture of a poor boy drinking clean water from a tap. That results in a doubling in nominal amounts of donations for the charity. Moreover, I find that people who already before the experiment are sympathetic to donating the pledge do so to a greater extent than people who were not. Neither sex nor age seemed to affect the results in any way.
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Investigation of Ageing effects and Image stability in Hybrid Photon Pixel detectors at the LHCb experiment CERN / Undersökning av åldringseffekter och bildstabilitet i hybrida foton-pixel-detektorer vid LHCb experimentet CERNMollén, Albert January 2010 (has links)
The world’s largest particle accelerator, Large Hadron Collider, located at CERN outside Geneva performed its first proton-proton collisions in November 2009. One of the four main experiments is LHCb, studying rare decays of hadrons containing the beauty quark. An essential part of the particle identification in LHCb is made by the two Ring Imaging Cherenkov detectors. These detectors use pixel Hybrid Photon Detectors for detection and imaging of Cherenkov rings. This paper reports on measurements carried out on the Hybrid Photon Detectors, including a discussion of the results. In particular, ageing effect and image stability are studied. A fraction of the photon detectors show a degradation in performance within these fields. / Världens största partikelaccelerator, LHC, belägen vid CERN utanför Genève utförde sina första proton-proton kollisioner i November 2009. Ett av de fyra huvudexperimenten är LHCb, som studerar sällsynta sönderfall av hadroner innehållande b kvarken. En viktig del av partikelidentifikationen i LHCb görs av de två RICH detektorerna. Dessa använder hybrida fotondetektorer för detektering och avbildning av Cherenkov ringar. Denna rapport handlar om mätningar utförda på dessa hybrida fotondetektorer, med en diskussion av resultaten. I synnerhet studeras åldringseffekter och bildstabilitet. En andel av fotondetektorerna visar en degradering i prestanda inom dessa områden.
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Study of Methane Reforming in Warm Non-Equilibrium Plasma DischargesParimi, Sreekar 2010 December 1900 (has links)
Utilization of natural gas in remote locations necessitates on-site conversion of methane
into liquid fuels or high value products. The first step in forming high value products is
the production of ethylene and acetylene. Non-thermal plasmas, due to their unique nonequilibrium
characteristics, offer advantages over traditional methods of methane
reforming.
Different kinds of non-thermal plasmas are being investigated for methane reforming.
Parameters of these processes like flow rate, discharge size, temperature and other
variables determine efficiency of conversion. An efficient process is identified by a high
yield and low specific energy of production for the desired product. A study of previous
work reveals that higher energy density systems are more efficient for methane
conversion to higher hydrocarbons as compared to low energy density systems. Some of
the best results were found to be in the regime of warm discharges. Thermal equilibrium
studies indicate that higher yields of ethylene are possible with an optimal control of
reaction kinetics and fast quenching. With this idea, two different glow discharge reactor
systems are designed and constructed for investigation of methane reforming. A counter flow micro plasma discharge system was used to investigate the trends of methane
reforming products and the control parameters were optimized to get best possible
ethylene yields while minimizing its specific energy. Later a magnetic glow discharge
system is used and better results are obtained. Energy costs lower than thermal
equilibrium calculations were achieved with magnetic glow discharge systems for both
ethylene and acetylene. Yields are obtained from measurements of product
concentrations using gas chromatography and power measurements are done using
oscilloscope. Energy balance and mass balances are performed for product measurement
accuracy and carbon deposition calculations. Carbon deposition is minimized through
control of the temperature and residence time conditions in magnetic glow discharges.
Ethylene production is observed to have lower specific energies at higher powers and
lower flow rates in both reactors. An ethylene selectivity of 40 percent is achieved at an
energy cost of 458MJ/Kg and an input energy cost of 5 MJ/Kg of methane.
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Investigation Of Dc Generated Plasmas Using Terahertz Time Domain SpectroscopyKaraoglan, Gulten 01 June 2010 (has links) (PDF)
This thesis is on the topic of investigation of the characteristics of DC Glow Discharge plasmas. Emphasis is given on characterizing the plasma electron density. The methods of generating and detecting THz pulses are described. THz transmission spectroscopy and plasma emission spectroscopy is examined. Transmission spectrum is taken for Air, gaseous Nitrogen and Argon plasmas. Moreover, emission spectrum of Air, N2 and Ar plasma analysis were done respectively. It was found that the transmission of terahertz pulses through nitrogen plasma was considerably affected compared to that of the argon plasma. Initially Drude model theory of electron conduction is employed to analyze the plasma density.
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Numerical Investigation Of Self-organization And Stable Burning Conditions Of Moderate Pressure Glow Discharges In Argon GasEylenceoglu, Ender 01 September 2011 (has links) (PDF)
In this study numerical modelling of a moderate pressure DC glow discharge plasma is car-
ried out in 1D and 2D geometry. The governing equations include continuity equations for the
plasma species (electrons, positive ions and metastable atoms), the electron energy equation
(EEE), Poisson equation for the electric
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Electronic Ballast for Starting Fluorescent Lamps with Zero Glow CurrentLee, Mu-en 21 January 2003 (has links)
This thesis proposes a single-stage high-power-factor electronic ballast with series-resonant inverter for rapid-start fluorescent lamps with zero glow current during preheating period. A buck-boost converter is integrated into the ballast as the power-factor-corrector. Two auxiliary windings are wound on the same core of the buck-boost inductor for filament heating.
During the preheating period, the buck-boost converter is initiated while the series-resonant inverter is disabled by controlling the corresponding active power switches. Due to zero voltage across the lamp, the glow current can be effectively eliminated. As the filaments reach appropriate emission temperature, the series-resonant inverter is activated. The lamp is then ignited and consequently operated at the rated lamp power.
Circuit analyses and experimental tests of the proposed preheating control scheme are carried out on an electronic ballast for a T8-40W rapid-start fluorescent lamp.
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Where is the warm glow? : the labour market in the voluntary sectorRutherford, Alasdair C. January 2011 (has links)
Why do people work in the voluntary sector? Is the sector distinct, with characteristics that differentiate it from the private and public sectors? Is it important to consider the existence of the so-called ‘third sector’ when analysing behaviour in the labour market? Is altruism really an important motivation for workers in this sector? This dissertation is concerned specifically with the labour market in the voluntary sector: that is, workers who are the paid employees of independent nonprofit organisations. Using a large, national dataset, we explore empirically the predictions of the economic theory of voluntary organisations. In particular, is there evidence for a ‘warm glow’, the extra utility that workers receive for working towards a goal that they share with their employer? Does this glow exist, and is it brighter in the voluntary sector? We examine in turn sector differences in wages, working hours, and find evidence that employment in the voluntary sector is significantly different in some characteristics from both the private and public sectors. The main economic theories of voluntary sector wage-setting rely on some formulation of ‘warm glow’ utility or intrinsic motivation derived from working for an organisation with a mission shared by motivated employees. This leads to a prediction of lower wages in the voluntary sector. The empirical findings in the existing literature have focussed on US data, and the results have been mixed. Using pooled cross-sectional and panel datasets based on UK employment data between 1997 and 2007, we show that there is some evidence of warm-glow wage discounts in the sector for male workers, but that these wage differences have been eroded as the sector has grown. Although there is not a significant sector wage difference found for women, there is evidence that they have also experienced faster wage growth in the voluntary sector than the private. There are significant sector differences in working hours within the Health & Social Work industries, particularly in overtime working. Workers in the voluntary sector work more hours of unpaid overtime, whilst those in the private sector work more hours of paid overtime. Controlling for overtime hours has a significant effect on sector wage differentials. In particular, accounting for unpaid overtime results in evidence of a warm-glow wage discount for female workers. We analyse this data at a time when the sector has been growing dramatically, driven by government policy to reform public services. Our findings suggest that this policy has had unintended consequences for the voluntary sector labour market.
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Computational studies of electron transport and reaction rate models for argon plasmaMin, Timothy T. 20 December 2010 (has links)
A validation study was performed on a capacitively coupled argon discharge
to determine the most suitable models for chemistry and electron
transport. Chemical reaction rate and electron transport models choices include
equilibrium or non-equilibrium electron EDFs. Experimental studies
performed by our collaborative partners in the Colorado School of Mines.
Conditions for the studies are 138, 315, and 618 mTorr where the cycle averaged
power varied at 20, 50, and 80 Watts in which the voltage supply
was driven at 13.56 MHz. Simulations were performed using pressures and
voltage used in experiments. The most accurate case was for 138 mTorr
at 50 Watts using a non-Maxwellian EDF based chemistry (called Bolsig+
chemistry) and a constant electron momentum transfer cross section of 20
Angstroms which was computed from Boeuf’s paper; this model accurately
modeled power deposition to within 2.6%. Furthermore, species number densities, electron temperature, and sheath thicknesses are obtained. Using
Bolsig+ chemistry resulted in 20,000K higher electron temperatures than
using Arrhenius chemistry rates. Results indicate that power deposition occurs
due to electrons gaining energy from the sheath which in turn bombard
neutral species producing metastable argon. / text
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