L'industrie des semi-conducteurs fait aujourd'hui face à des challenges importants en termes de caractérisation. En effet, la diminution des tailles et des distances inter-objets a poussé les techniques, jusqu’alors utilisées sur les lignes de production, la microscopie (SEM) et l’ellipsométrie (OCD) ont montré plusieurs limites.. Ainsi, afin de répondre aux demandes de l’industrie, soit un contrôle précis de l’uniformité et des défauts en cours de production, des besoins en termes de métrologie sont apparus.Dans ce contexte, des techniques utilisant les rayons X ont commencé à être évaluée. Ainsi, le SAXS (Small Angle X-Ray Scattering) est une technique de diffusion des rayons X aux petits angles (angles d’incidences compris entre 0.1 et 10°) permettant l’étude d’objets de taille comprise entre 1 et 100 nm. Cette technique consiste à bombarder un échantillon avec des rayons X et à collecter grâce à un détecteur les photons traversant l’échantillon (étude en transmission). Elle est sensible au contraste de densité électronique à l’intérieur de l’échantillon. C’est une technique complémentaire aux techniques de caractérisation locale telles que les microscopies, car elle permet d’obtenir une information moyennée sur une grande surface (plusieurs mm2). Une seconde technique, le GISAXS (Grazing-Incidence SAXS) est également en plein développement. C’est une technique analogue au SAXS cependant, le faisceau de rayons X ne traverse plus l’échantillon mais est réfléchi par celui-ci. Ce qui permet l’étude de films minces ou de nanoobjets déposés sur des surfaces. Ces deux techniques sont non destructives. L’objectif de cette thèse a été d’implanter ces deux techniques au sein de la plateforme de nanocaractérisation du CEA-LETI et de montrer le leurs pertinences et leurs capacités à répondre aux demandes de l’industrie de la micro-électronique. Pour se faire la thèse se divise en deux thématiques.Dans un premier temps, des études de Contrôle-Dimensionnel SAXS (CD-SAXS) ont été réalisées sur des réseaux d’objets tridimensionnels, tels que des réseaux de lignes ou d’empilement multicouches avec des applications autour de la lithographie. Nous avons ainsi pu mettre en évidence la capacité du CD-SAXS à extraire la période et la largeur de lignes ainsi que leurs profils (hauteur de lignes et angles de parois notamment) avec une précision sub-nanométrique. De plus, la caractérisation de rugosité le long des lignes a également été étudiée. Les résultats autour du CD-SAXS sont prometteurs et permettent aujourd’hui d’envisager des approches multi-techniques afin de combiner par exemples les informations locales obtenues par microscopie et les informations statistiques obtenues par SAXS.Dans un second temps, des études GISAXS sur des films de copolymères à blocs ont été réalisées, avec pour objectifs l’utilisation de ces films comme masques pour la lithographie. Tour d’abord le système classique PS-b-PMMA a été étudié à haute énergie, et plus précisément le retrait d’un des deux blocs de polymères uniquement. Puis des mesures au seuil du carbone ont également été réalisées afin de montrer la capacité des rayons X à différencier deux espèces très proches chimiquement. De nouveaux systèmes de copolymères dit "high chi" (avec une plus grande répulsion entre bloc) ayant pour objectifs la génération d’objets plus petits ont également été étudiés. Pour finir l’approche développée au CEA nommée contact hole shrink a également été suivie par GISAXS et comparé avec les résultats obtenus par CD-SAXS. / The semiconductor industry now faces significant challenges in terms of characterization. Indeed, the size and inter-object distances reduction pushed the techniques previously used, such as microscopy (SEM) and ellipsometry (OCD) to their limitations. So in order to cope with demand of the industry (a precise control of the uniformity and defects) some needs in terms of metrology appeared.In this context, X-ray techniques were evaluated. Therefore, X-ray scattering at small angle (SAXS), using incident angles comprise between 0.1 and 10° to detect 1-100 nm objects, was studied. This technique consists on sending X-ray on a sample and to collect thanks to a 2D detector the photon going through the sample (study in transmission). This technique will detect the electronic density contrast in the sample and is nondestructive. Moreover, the statistical information over a large area (several mm2) obtained from SAXS is complementary with the local and direct information obtained from microscopies. A second technique called GISAXS (Grazing-incidence SAXS) was also tested. The X-ray beam is no more transmitted through the sample but reflected on the substrate. GISAXS is more adapted for the study of thin films and nano-objects deposited on substrate. The aim of this thesis was the implementation of SAXS and GISAXS techniques on the nanocharacterization platform of the CEA-LETI and the demonstration of the ability of such techniques to control the dimension and morphologies of samples coming from the micro-electronics industry. This thesis was divided in two parts.The first one deals with critical-dimension SAXS. The control of profiles and size of 3D arrays, such as line gratings or multilayer samples, were performed on samples related to lithographic applications. We showed the capability of CD-SAXS to extract the period, the line width and the line profile (height and sidewall angle) with a sub-nanometer resolution of line gratings. Therefore, line roughness was also studied, showing promising results on periodic roughness with sub-nanometer amplitudes. Results around CD-SAXS led to new possibilities such as the multi-scale approaches, with several techniques to control in the same time the local structure, with microscopes, and the statistical structures with CD-SAXS.Secondly, GISAXS studies were performed on block copolymer films used as masks for lithography. First, the conventional system PS-b-PMMA was studied at high energy and more precisely, the removal of the PMMA bloc only. Then measurements at the carbon were also carried out to demonstrate the ability of X-rays to differentiate between two materials with quasi-similar chemical compositions. Therefore, new copolymer systems, called "high chi" (with higher repulsion between block) were also studied. Such polymers lead to the reduction of the obtained patterns. Finally the contact hole shrink approach developed at CEA was also studied by GISAXS and compared with results obtained by CD-SAXS.

Thesis (MSc (Radiography))--Cape Peninsula University of Technology, 2018. / Background and objectives The issue of patient doses received during fluoroscopy procedures, raised concerns for the researcher, as there may have been probable past skin injuries or deterministic injuries that may not have been documented. Amongst the radiology staff, there was very little understanding of what the actual dose area product (DAP) value means in real terms of effective dose and entrance skin dose. The aims of the study were to: i) Measure the radiation doses received by the patient and determine a simple means of defining the DAP value to the radiographer in terms of the dose received by the patient. ii) Determine the effective dose, entrance skin dose and the relationship with the DAP value to assist with developing a conversion co-efficient for dose indicators. Method Direct radiation dose measurements can be obtained through DAP meters attached to the diagnostic equipment, but the DAP value is not an direct indication of the effective dose received by the patient. The DAP values captured from the DICOM header information for barium fluoroscopic procedures at a large tertiary was analysed and Diagnostic Reference levels (DRL) were determined for barium swallow, meal and enema procedures. The effective and skin doses were calculated by means of the Monte Carlo program. The results were compared to published values. The relationship between the entrance skin dose and the DAP value was determined and conversion factors were calculated. Results Correlation between the DAP and entrance skin dose and comparative 75th percentile threshold values were determined for barium swallow (BaS), barium meal (BaM) and barium enema (BaE) procedures. Effective to DAP conversation factors for BaS, BaM and BaE are 0.19, 0.26 and 0.60 respectively and 0.15, 0.11 and 0.14 for entrance skin to DAP. Conclusion The the research showed the relationship between the effective dose, entrance skin dose and DAP value and a simple, practical and applicable explanation of the DAP value by means of conversion factors.

O conhecimento da distribuição espectral da radiação X emitida por unidades de radiodiagnóstico fornece importantes informações, que podem ser aplicadas aos programas de Garantia de Qualidade e de Proteção Radiológica. Detectores que utilizam fotodiodos PIN de Si como ponta de prova vêm sendo utilizados nos últimos anos devido, principalmente, ao seu baixo custo e por trabalharem a temperatura ambiente, não precisando dos tanques de nitrogênio líquido necessários em detectores de Ge e Si(Li). Embora, a princípio, os fotodiodos PIN tenham uma pior resolução, quando comparada com os detectores de Ge, ela é suficientemente boa para a maior parte das aplicações em radiodiagnóstico. Além disso, o desenvolvimento de sistemas refrigerados termoelétricamente e de pré-amplificadores de baixo ruído têm feito com que os fotodiodos PIN cheguem a resoluções comparáveis às do Ge. Este trabalho visa estabelecer as propriedades de detectores constituídos por fotodiodos PIN de Si e desenvolver o processo de correção dos espectros brutos para a eficiência do detector e outros fatores pertinentes, a fim de se obter o espectro real emitido por equipamentos de radiodiagnóstico. Espectros de radiação de equipamentos de radiodiagnóstico obtidos experimentalmente foram comparados com espectros teóricos calculados a partir de um modelo semi-empírico. Além disso, foram obtidos espectros de radiação emitidos por unidades de mamografia, espalhados por um objeto simulador de mama. Como aplicação direta dos espectros medidos experimentalmente, foram desenvolvidas metodologias para a determinação da tensão aceleradora de tubos de Raios X (kVp), para fins de calibração de medidores de kVp, e da camada semi-redutora (CSR) dos feixes de interesse. / Knowledge of the spectral distribution of radiation emitted by radiodiagnostic units provides important information, which can be applied to the Quality Assurance and Radiological Protection programs. Detectors which utilize Silicon PIN Photodiodes have been increasingly used in recent years, due to their low cost and being worked with at room temperature, the liquid nitrogen containers used with Ge and Si(Li) detectors not being necessary. Although, initially, the PIN photodiodes have a poorer energy resolution, as compared with Ge detectors, it\'s good enough for most purposes. Moreover, the development of thermoelectrically cooled systems and low noise level pre-amplifiers have resulted in PIN photodiodes achieving comparable resolutions to Ge ones. This work seeks to establish the properties of detectors made with Silicon PIN photodiodes and to develop the correctional process of the raw specffa both for the efficiency of the detector and other relevant factors, with the aim of obtaining the true spectrum emitted by radiodiagnostic equipment. The radiation spectra of radiodiagnostic equipment experimentally obtained were compared with theoretical spectra calculated from a semi-empirical model. Furthermore, mammography x-ray spectra scattered by a breast simulator were obtained. As a direct application of these experimentally measured spectra, methodologies were developed to determine the peak kilovoltage (kvp) of X-Ray tubes, to be able to calibrate kVp meters, and the half-value layer (HW) of the beams of interest.

Orientador: Solange Maria de Almeida / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-22T22:27:04Z (GMT). No. of bitstreams: 1 Gomes_CarolinaCintra_D.pdf: 2371162 bytes, checksum: a83060f2fb962062c6ec3fa55ea99748 (MD5) Previous issue date: 2013 / Resumo: Nesse estudo teve-se como objetivo avaliar o efeito do alendronato de sódio e de 15 Gy de radiação X no processo de reparação tecidual de defeitos ósseos e na microarquitetura óssea em ratas com deficiência de estrogênio. Foram utilizadas quarenta ratas (Rattus Norvegicus, Albinus Wistar), adultas, com idade de 90 dias. Os animais foram divididos aleatoriamente nos seguintes grupos: Controle ovariectomizado, Ovariectomizado / Alendronato, Ovariectomizado / Irradiado, Ovariectomizado / Alendronato / Irradiado. O alendronato (5 mg/kg corpóreo) foi administrado durante quatro semanas nos grupos Ovariectomizado / Alendronato e Ovariectomizado / Alendronato/ Irradiado. Doze dias após a terapêutica com alendronato de sódio um defeito ósseo foi confeccionado na tíbia esquerda dos animais. Três dias após, os grupos Ovariectomizado /Irradiado e Ovariectomizado / Alendronato / Irradiado tiveram os membros posteriores irradiados com 15 Gy de radiação X. As eutanásias ocorreram 10 e 33 dias após a confecção dos defeitos ósseos. O reparo ósseo foi analisado por histomorfometria e a microarquitetura óssea analisada por micro-TC. Em relação ao processo de reparação tecidual dos defeitos ósseos, a radiação X e o alendronato não apresentaram efeitos significativos (p > 0,05). Em relação à microarquitetura óssea, a radiação X aumentou a espessura da cortical óssea no tempo de 10 dias (p < 0,05); e no tempo de 33 dias, diminuiu o número de trabéculas por unidade de comprimento e aumentou a distância média entre as trabéculas (p < 0,05); o alendronato de sódio inibiu o efeito deletério da radiação X evitando o aumento da distância entre as trabéculas e a redução do número de trabéculas por unidade de comprimento no tempo de trinta e três dias (p < 0,05). Nessas condições experimentais conclui-se que a radiação X apresentou um efeito deletério sobre a microarquitetura óssea e o alendronato de sódio preservou o tecido ósseo submetido à radiação X / Abstract: The aim of the present study was to evaluate the effect of sodium alendronate in the process of tissue repair of bone defects, artificially produced in estrogen-compromised rats irradiated with 15 Gy. We selected forty female adults rats (Rattus norvegicus, Wistar Albinus), aged 90 days. The animals were randomly divided into the following groups: ovariectomized; ovariectomized-alendronate; ovariectomized-irradiated; and ovariectomized-alendronate-irradiated. Sodium alendronate (5 mg/kg) was administered three times a week, for four weeks, in ovariectomized-alendronate and ovariectomized-alendronate-irradiated groups. Twelve days after the end of treatment with alendronate, a bone defect was created in animals' left tibia. Three days later, the posterior legs of ovariectomized-irradiated and ovariectomized-alendronate-irradiated group animals were irradiated with 15 Gy. The euthanasias occurred 10 and 33 days after bone defects creation. The presence of bone repair was analyzed by histomorphometry, and the bone microarchitecture was analyzed by micro computed tomography. In relationship to the process of tissue repair on osseous defects, the X radiation and the alendronate do not represent significant effects (p > 0,05). In relationship to the osseous microstructure, the X radiation increased the thickness of the cortical bone in the time of 10 days (p < 0,05); decreased the number of trabeculae per unit of length and increased the medium distance between the trabeculae in the time of 33 days (p < 0,05); the sodium alendronate inhibited the deleterious effect of the X radiation avoiding the increase in distance between the trabeculae and reduced the number of trabeculae per unit of length in the time of 33 days (p < 0,05). In these experimental conditions it is concluded that the radiation X had a deleterious effect on bone microarchitecture and alendronate sodium preserved bone tissue subjected to the radiation X / Doutorado / Radiologia Odontologica / Doutora em Radiologia Odontológica

Emission from X-ray binaries is variable on a wide range of timescales. On long timescales, changes in mass accretion rate drive changes in spectral state. There is also rapid variability, the power spectrum of which consists of a low frequency quasi-periodic oscillation (QPO) superimposed on a broad band noise continuum. Here I investigate a model intended to quantitatively explain the observed spectral and variability properties. I consider a truncated disc geometry whereby the inner regions of an optically thick, geometrically thin accretion disc evaporate to form an optically thin, large scale height accretion flow. The QPO is driven by Lense-Thirring precession of the entire hot flow and the broad band noise is due to fluctuations in mass accretion rate which propagate towards the central object. Mass conservation ties these two processes together, enabling me to define a model for the QPO and broad band noise which uses only one set of parameters. I am thus able fit the model to data. The accretion rate fluctuations drive fluctuations in the precession frequency, giving rise to a quasi-periodic oscillation rather than a pure periodicity. The model thus predicts recent observations which show the QPO frequency to correlate with flux on short timescales. I then investigate a more unique model prediction. As the flow precesses, the patch of the disc preferentially illuminated by the flow rotates such that a non face on observer sees a quasi-periodic shift between blue and red shift in the iron K alpha line. An observation of such an effect would constitute excellent evidence for the model.

The crystal structure of caesium permanganate has been determined. CsMn0₄ crystallises in the orthorhombic space group Pnma. There are four molecules per unit cell with a = 10.0692 Å, b = 5.8080 Å, c = 7.9470 Å. The structure was determined by Fourier syntheses on the (010) and (001) projections and refined by two-dimensional difference syntheses. The structure is similar to that of KMn0₄. The manganese is surrounded by four oxygen atoms at an average distance of 1.629 Å arranged in a slightly distorted tetrahedron. The caesium is surrounded by eight manganese atoms at an average distance of 4.381 Å.

M.Sc. (Geology) / This study involves the quantitative analysis of fluorspar-containing slurries by two X-ray diffraction methods, whereby these two methods of on-stream analysis are compared. The first method involves a single counter with a diffracted beam monochromator, and the second method involves a fixed geometry with an incident beam monochromator. The second method is a cheaper and more robust apparatus, which can withstand the harsh environment of the flotation plants. A new algorithm was developed for a more accurate calibration method. Programmes for calibration, recalibration and measuring of unknown samples were developed. The measuring apparatus was interfaced with a microcomputer for computerised operation of the system. Results from both methods were comparable, with more accurate results obtained for the feed and tailings than for the concentrate samples. The single detector apparatus can thus be replaced by the fixed geometry model, which is less expensive and more robust.

M.Phil. (Energy Studies) / Non-destructive investigations of unusual natural polycrystalline diamond samples are reported. The samples originate from various international locations discovered in soils and sediments and may have been formed by di erent mechanisms which are the subject of debate. Analysis techniques include scanning electron microscopy, with energy dispersive spectroscopy and X-ray di raction. Sample composition, structure and surface stresses were investigated. The samples (two Egyptian nodules, two Brazillian carbonados, two Venetian ballas diamonds and a polycrystalline diamond compact sample consisting of a polycrystalline diamond layer sintered onto a Co-cemented tungsten carbide support) are cubic diamonds, with varying amounts of minority phases. In most cases the minority phases could not be identi ed unambiguously due to their low intensities and the overlap of Bragg peaks. The Egyptian nodule samples in particular showed a large presence of oxygen that could not be linked to speci c metal oxides. The Ballas samples had the lowest impurity content. Using a Rietveld based quanti cation analysis, the crystalline cubic diamond contents were determined respectively as 99 wt.%, 98 wt.% and 76 wt.% in the Ballas, Brazilian carbonado and Egyptian nodule samples. A signi cant result from this study is the substantial inhomogeneous peak broadening observed in the X-ray diffraction patterns of the Egyptian samples. This is indicative of the presence of nano-crystalline diamond grains in addition to substantial mechanical deformation with extensive accumulation of dislocations and crystalline defects. These observations are supportive of a recently proposed impact mechanism for their formation.

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