The absolute abundances of fission-product xenon and krypton isotopes in six uranium minerals were determined mass spectrometrically using the isotope dilution technique. The fission products were resolved into a U spontaneous fission component, a U 235 neutron-induced fission component, and a U 238 neutron-induced fission component. The presence of U 238 of neutron-induced fission indicated that t he neutron energies in uranium minerals were higher than had been suspected. Internal consistency in the analysis was achieved only when the I 29 yield in u235 thermal neutron fission reported by Purkayastha and Martin was lowered by 20%. The number of U 238 spontaneous fissions was calculated from the lead age, U 238 content, and the U 238 pontaneous fission half life. A comparison of the number of fission products from U 238 spontaneous fission and the number of spontaneous fissions in each of the six minerals showed that five of the six minerals had lost large portions of their noble gases. A fractionation of krypton relative to xenon accompanied this loss. The results obtained for the sixth mineral indicated little or no loss of xenon and krypton. Absolute yields for U 238 spontaneous fission were therefore determined from an analysis of this mineral. / Thesis / Doctor of Philosophy (PhD)

The object of this work was to develop a linear two-point reactor model from an existing nonlinear model and determine optimum parameters for both models in comparison to actual plant data. The importance of keeping the nonlinearity to accurately describe the xenon oscillation problem was also examined. The best chi-square fit to the actual test data was established as the guiding criterion. The nonlinear model initially produced an excellent chi-square fit of 0.708 against plant data. This value could only be reduced through parameter variation to 0.695, approximately 2%. The linear model resulted in a diverging oscillation at the initial one group estimates. Linearizing the oscillatory behavior of the xenon burnup coefficient was attributed to the decrease in the stability of the model. The major flaw of the linear model was the dependence of the nonlinear model for initial conditions. / M. S.

L’imagerie 3γ est une nouvelle technique d’imagerie médicale nucléaire qui a été proposée au laboratoire Subatech. Cette technique consiste à localiser tridimensionellement la position de la désintégration d’un radioisotope innovant émetteur (β+, γ), le 44Sc. Il s’agit pour cela d’associer la détection des deux photons gamma de 511 keV issus de la désintégration d’un positon, assurée par une couronne de détecteurs de tomogaphie à émission de positon, à la détection dutroisième photon par un télescope Compton au xénon liquide. La position de l’interaction entre le photon et le xénon, ainsi que l’énergie déposée, sont relevées grâce à la mesure du signal d’ionisation à l’aide d’un chambre MICROMEGAS (MICROMEsh GAseousStructure), tandis que le déclenchement de l’acquisition et la mesure du temps de l’interaction sont assurés parla détection du signal de scintillation. Le principe de la TPC est ainsi utilisé pour l’imagerie Compton.Afin de faire la preuve expérimentale de faisabilité de l’imagerie 3γ, un prototype de petite dimension, XEMIS (XEnon Medical Imaging System), a été développé.Cette thèse constitue une étape importante vers cette preuve de faisabilité. Les travaux qui y sont exposés portent sur la caractérisation de la réponse du détecteur pour un faisceau de gammas de 511 keV et sur l’analyse des données qui en sont issues. La mesure des résolutions en énergie et temporelle seront exposés, ainsi que celle de la pureté du xénon liquide. / 3γ imaging is a new nuclear medical imaging technique which has been suggested by Subatech laboratory. This technique involves locating three-dimensional position of the decay of an innovative radioisotope (β+, γ) emitter the 44Sc. The principle consist in the detection of two photons of 511 keV gamma rays from the decay of the positron, provided by a PET ring detector, associated to the detection of the third photon by a Liquid xenon Compton telescope. The energy deposited in the interaction between the photon and xenon and its position are identified by measuring the ionization signal with a MICROMEGAS chamber (MicroMesh Gaseous Structure), while the trigger and time measurement of the interaction are provided by the detection of thescintillation signal. The principle of the TPC is thus usedto Compton imaging.In order to demonstrate experimentally the feasibility of imaging 3γ, a small prototype, XEMIS (Xenon MedicalImaging System) was developed. This thesis is an important step towards the proof of feasibility. In this work are exposed the characterization of the detector response for a beam of 511 keV gamma rays and the analysis of data derived from it. The measurement of energy and time resolutions will be presented, as well as the purity of the liquid xenon.

Thesis--University of Copenhagen. / Resumé in Danish. Bibliography: p. [171]-184.

Thesis--University of Copenhagen. / Resumé in Danish. Bibliography: p. [171]-184.

This thesis presents the results of a study of the mechanisms responsible for limiting the laser pulse duration obtainable in xenon chloride lasers which are excited by UV-preionized, self-sustained gas discharges. The xenon chloride laser system, the principal emission band of which is centred around 308 nm, belongs to the class of high pressure gas lasers known as 'rare-gas halides'(RGH). RGH lasers are now well known for their high peak power output at a number of wavelengths from 193 nm to 353 nm in the ultraviolet region of the spectrum. To date, however, they have only been operated in the pulsed mode with laser pulse durations of ^~1000 ns for devices employing electron beam excitation and ^~30 ns for devices employing transverse discharge excitation. There is no a priori kinetic limitation which prevents RGH lasers from operating in the CW mode, and an attempt to extend the duration of the laser pulse would enable the quality of laser output to be improved. The laser pulse duration of a discharge excited XeCl^* laser was extended by about one order of magnitude - to 270 ns FWHM - by the use of a distributed resistance electrode to stabilize the discharge. The typical gas mixture used in the laser was ~2 atm of Ne (buffer gas), ~25 mbar of Xe, and 2.5 mbar of HC1. However, the laser pulse duration obtained was considerably shorter than the 500 ns duration, 2000 A peak current, discharge excitation pulse. The cause of this difference between the duration of the laser output pulse and the discharge current pulse was found by carrying out a comprehensive parametric study of the laser, combined with a detailed spectroscopic analysis and the results of a semi-empirical computer model. Two interrelated factors were identified as being responsible for the short duration of the laser output: namely, a temporal collapse of the discharge volume and a spatially non-uniform depletion of the HCl within this volume. The experimental results presented here contradict an earlier theory which ascribed the onset of discharge instabilities in RGH lasers to step-wise ionization of the minority rare gas atoms, and which attributed stability enhancement properties to the electronegative halogen gases used in RGH lasers.

Over much of the last century evidence has been building for a new component of our universe that interacts primarily through gravitation. Known as cold dark matter, this non-luminous source is predicted to constitute 83% of matter and 26% of mass-energy in the universe. Experiments are currently searching for dark matter via its possible creation in particle colliders, annihilation in high-density regions of the universe, and interactions with Standard Model particles. So far dark matter has eluded detection so its composition and properties remain a mystery. Weakly interacting massive particles (WIMPs) are hypothetical elementary particles that interact on the scale of the weak nuclear force. They naturally satisfy predictions from extensions of the Standard Model, and are one of the most favored dark matter candidates. A number of direct detection experiments dedicated to measuring their predicted interactions with atomic nuclei have been constructed over the last 25 years. Liquid xenon dual phase time projection chambers (TPCs) have led the field for spin-independent WIMP searches at WIMP masses of >10 GeV/c^2 for most of the last decade. XENON1T is the first tonne-scale TPC, and with 278.8 days of dark matter data has set the strictest limits on WIMP-nucleon interaction cross sections above WIMP masses of 6 GeV/c^2, with a minimum of 4.1 x10^{-47} cm^2 at 30 GeV/c^2. XENON1T and the analysis that led to this result are discussed, with an emphasis on electronic and nuclear recoil calibration fits, which help discriminate between background and WIMP-like events. Interactions in liquid xenon produce light and charge that are measured in TPCs. These signals are attenuated by electronegative impurities including O_2 and H_2O, which are homogeneously distributed throughout the liquid xenon. The decrease in observables enlarges the uncertainty in our analysis, and can decrease our sensitivity. Methods on measuring the charge loss are presented, and a physics model that describes the behavior of the electronegative impurity concentration over the lifetime of XENON1T is derived. The model is shown to successfully explain the more than two years of data.

High Harmonic Generation (HHG) enables the production of bursts of coherent soft x-rays with attosecond pulse duration. This process arrises from the nonlinear interaction between intense infrared laser pulses and an ionizing gas medium. Soft x-ray photons are used for spectroscopy of inner-shell electron correlation and exchange processes, and the availability of attosecond pulse durations will enable these processes to be resolved on their natural time scales. The maximum or cutoff photon energy in HHG increases with both the intensity as well as the wavelength of the driving laser. It is highly desirable to increase the harmonic cutoff as this will allow for the generation of shorter attosecond pulses, as well as HHG spectroscopy of increasingly energetic electronic transitions. While the harmonic cutoff increases with laser wavelength, there is a corresponding decrease in harmonic yield. The first part of this thesis describes the experimental measurement of the wavelength scaling of HHG efficiency, which we report as lambda^(-6.3) in xenon, and lambda^(-6.5) in krypton. To increase the HHG cutoff, we have developed a 1.8 um source, with stable carrier envelope phase and a pulse duration of <2 optical cycles. The 1.8 um wavelength allowed for a significant increase in the harmonic cutoff compared to equivalent 800 nm sources, while still maintaing reasonable harmonic yield. By focusing this source into neon we have produced 400 eV harmonics that extend into the x-ray water window. In addition to providing a source of photons for a secondary target, the HHG spectrum caries the signature of the electronic structure of the generating medium. In krypton we observed a Cooper minimum at 85 eV, showing that photoionization cross sections can be measured with HHG. Measurements in xenon lead to the first clear observation of electron correlation effects during HHG, which manifest as a broad peak in the HHG spectrum centred at 100 eV. This thesis also describes several improvements to the HHG experiment including the development of an ionization detector for measuring laser intensity, as well as an investigation into the role of laser mode quality on HHG phase matching and efficiency.

The project this report is handling has been implemented on NBB, Nordisk Bilbelysning AB in Linköping. The company produces and develops lightning and searchlights for all types of vehicles. Lately NBB´s supplier of electronics, OSRAM, has developed a mercuryfree xenon lightsource. Mercury is one of the most hazardous environmental waste and to get rid of the mercury entirely in the lightsource is a big step that means alot for the environment. This lightsource will be placed in one of NBB´s worksearchlights called My, and will be sold as an alternative to mercurycontaining searchlights. NBB wants to put an environmental label on this product and they want to have essential information about the product that is needed for the production. That is what the project has handled. A study of environmental labeling has been made witch has led to that an environmental declaration type II will be used as labeling and marketing for the environmental properties the serachlight has. The purpose of this master's thesis is to help and support NBB in environmental labeling and developing of a My searchlight with mercuryfree lightsource. A environmental labeled searchlight would mean a bigger place on the market and consequently lowered environmental affect. Lifecycleanalysis with the program ECO-it shows that a mercuryfree lightsource in the searchlight would not involve a environmental profit compared to a mercurycontaining lightsource because the lifelenght of a mercuryfree lightsource is 500 hours shorter. This means that the lightsource has to be changed more frequently if you choose the mercury free alternative and that affects the environment. The lifecycleanalysis also shows that the transports of components affects the environment little in compare to the production of the product and therefore a change to Swedish suppliers has not been implemented. Temperatur and lightmeasures has been made and compared between the searchlight containing mercury with the searchlight not containing mercury. The results of the measurements shows that the flow of light from a mercury free searchlight is about 15% lower and the temperature inside 5°C higher. This means that the construction not has to be changed as the temperature is on a acceptable level. The use of mercury in lightsources will likely not be used forever as new law demands becomes stricter and stricter by time. The environmental declaration that was made contains among other things a list of materials of the product and information about the products lifecycle. A logotype has also been suggested as a environmental label logotype for the company to use. The environmental declaration will be used as marketing of the product on the company website for exemple. / Projektet som rapporten hanterar har ägt rum på NBB, Nordisk Bilbelysning AB i Linköping. Företaget tillverkar och utvecklar belysning och strålkastare till alla typer av fordon. På senare tid har NBBs leverantör av elektronik, OSRAM utvecklat en kvicksilverfri xenonljuskälla. Kvicksilver är ett av de farligaste miljögifterna och att få bort kvicksilvret helt ur ljuskällan är ett stort steg som betyder mycket för miljön. Denna ljuskälla ska NBB placera i en arbetsstrålkastare vid namn My och sälja som ett alternativ till kvicksilverinnehållade strålkastare. Denna produkt vill NBB miljömärka och ha fram väsentlig information om för att kunna påbörja tillverkningen. Detta är vad projektet har hanterat. Syftet med detta examensarbete är att hjälpa och stödja NBB i miljömärkning och framtagning av en My strålkastare med kvicksilverfri xenonljuskälla. En miljömärkt strålkastare skulle kunna innebära en större plats på marknaden och därmed minskad miljöpåverkan. En studie av miljömärkningstyper har gjorts vilket har lett till att miljövarudeklaration typ II är den typ av miljömärkning och marknadsföring av miljöegenskaper som använts. Livscykelanalyser med programmet ECO-it visar att en kvicksilverfri ljuskälla i strålkastaren i detta fall inte skulle innebära någon miljövinst jämfört med kvicksilverinnehållande ljuskälla. Det beror på att livslängden för en kvicksilverfri ljuskälla är 500 timmar kortare. Detta innebär i sin tur att ljuskällan måste bytas mer frekvent om man väljer det kvicksilverfria alternativet vilket i sin tur belastar miljön. Det har även visat sig att transporter av ingående detaljer ger en liten miljöpåverkan i jämförelse till produktionen av produkten. Detta skulle innebära att byta leveratörer till svenska leverantörer inte skulle innebära någon större miljövinst. Temperatur- och ljusmätningar har genomförts och jämförts mellan strålkastare med kvicksilverinnehållade ljuskälla och strålkastare med kvicksilverfri ljuskälla. Resultaten av provningarna visade att ljusflödet för en kvicksilverfri strålkastare var ungefär 15% lägre och temperaturen inne i strålkastaren ca 5°C högre. Detta innebär att konstruktionen inte måste ändras då temperaturen är på en godkänd nivå. Användandet av kvicksilver i ljuskällor kommer troligtvis inte ske för alltid då nya lagkrav hela tiden blir strängare och strängare. Den miljövarudeklaration som gjordes innehåller bland annat materiallista på produkten och information om produktens livscykel. Även en logotype har lagts fram som förslag på eget miljömärke till företaget. Miljövarudeklarationen kommer användas som marknadsföring av produkten bland annat på företagets hemsida.

<p>The project this report is handling has been implemented on NBB, Nordisk Bilbelysning AB in Linköping. The company produces and develops lightning and searchlights for all types of vehicles. Lately NBB´s supplier of electronics, OSRAM, has developed a mercuryfree xenon lightsource. Mercury is one of the most hazardous environmental waste and to get rid of the mercury entirely in the lightsource is a big step that means alot for the environment.</p><p>This lightsource will be placed in one of NBB´s worksearchlights called My, and will be sold as an alternative to mercurycontaining searchlights. NBB wants to put an environmental label on this product and they want to have essential information about the product that is needed for the production. That is what the project has handled. A study of environmental labeling has been made witch has led to that an environmental declaration type II will be used as labeling and marketing for the environmental properties the serachlight has.</p><p>The purpose of this master's thesis is to help and support NBB in environmental labeling and developing of a My searchlight with mercuryfree lightsource. A environmental labeled searchlight would mean a bigger place on the market and consequently lowered environmental affect.</p><p>Lifecycleanalysis with the program ECO-it shows that a mercuryfree lightsource in the searchlight would not involve a environmental profit compared to a mercurycontaining lightsource because the lifelenght of a mercuryfree lightsource is 500 hours shorter. This means that the lightsource has to be changed more frequently if you choose the mercury free alternative and that affects the environment.</p><p>The lifecycleanalysis also shows that the transports of components affects the environment little in compare to the production of the product and therefore a change to Swedish suppliers has not been implemented.</p><p>Temperatur and lightmeasures has been made and compared between the searchlight containing mercury with the searchlight not containing mercury. The results of the measurements shows that the flow of light from a mercury free searchlight is about 15% lower and the temperature inside 5°C higher. This means that the construction not has to be changed as the temperature is on a acceptable level.</p><p>The use of mercury in lightsources will likely not be used forever as new law demands becomes stricter and stricter by time. The environmental declaration that was made contains among other things a list of materials of the product and information about the products lifecycle. A logotype has also been suggested as a environmental label logotype for the company to use. The environmental declaration will be used as marketing of the product on the company website for exemple.</p> / <p>Projektet som rapporten hanterar har ägt rum på NBB, Nordisk Bilbelysning AB i Linköping. Företaget tillverkar och utvecklar belysning och strålkastare till alla typer av fordon. På senare tid har NBBs leverantör av elektronik, OSRAM utvecklat en kvicksilverfri xenonljuskälla. Kvicksilver är ett av de farligaste miljögifterna och att få bort kvicksilvret helt ur ljuskällan är ett stort steg som betyder mycket för miljön.</p><p>Denna ljuskälla ska NBB placera i en arbetsstrålkastare vid namn My och sälja som ett alternativ till kvicksilverinnehållade strålkastare. Denna produkt vill NBB miljömärka och ha fram väsentlig information om för att kunna påbörja tillverkningen. Detta är vad projektet har hanterat.</p><p>Syftet med detta examensarbete är att hjälpa och stödja NBB i miljömärkning och framtagning av en My strålkastare med kvicksilverfri xenonljuskälla.</p><p>En miljömärkt strålkastare skulle kunna innebära en större plats på marknaden och därmed minskad miljöpåverkan.</p><p>En studie av miljömärkningstyper har gjorts vilket har lett till att miljövarudeklaration typ II är den typ av miljömärkning och marknadsföring av miljöegenskaper som använts.</p><p>Livscykelanalyser med programmet ECO-it visar att en kvicksilverfri ljuskälla i strålkastaren i detta fall inte skulle innebära någon miljövinst jämfört med kvicksilverinnehållande ljuskälla. Det beror på att livslängden för en kvicksilverfri ljuskälla är 500 timmar kortare. Detta innebär i sin tur att ljuskällan måste bytas mer frekvent om man väljer det kvicksilverfria alternativet vilket i sin tur belastar miljön. Det har även visat sig att transporter av ingående detaljer ger en liten miljöpåverkan i jämförelse till produktionen av produkten. Detta skulle innebära att byta leveratörer till svenska leverantörer inte skulle innebära någon större miljövinst.</p><p>Temperatur- och ljusmätningar har genomförts och jämförts mellan strålkastare med kvicksilverinnehållade ljuskälla och strålkastare med kvicksilverfri ljuskälla. Resultaten av provningarna visade att ljusflödet för en kvicksilverfri strålkastare var ungefär 15% lägre och temperaturen inne i strålkastaren ca 5°C högre. Detta innebär att konstruktionen inte måste ändras då temperaturen är på en godkänd nivå.</p><p>Användandet av kvicksilver i ljuskällor kommer troligtvis inte ske för alltid då nya lagkrav hela tiden blir strängare och strängare. Den miljövarudeklaration som gjordes innehåller bland annat materiallista på produkten och information om produktens livscykel. Även en logotype har lagts fram som förslag på eget miljömärke till företaget. Miljövarudeklarationen kommer användas som marknadsföring av produkten bland annat på företagets hemsida.</p>