Made available in DSpace on 2014-10-09T12:35:50Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:03:40Z (GMT). No. of bitstreams: 0 / A perfilagem de colunas por raios gama (column gamma scan) é uma técnica nuclear empregada para solucionar problemas em equipamentos de processos industriais, nas refinarias e petroquímicas. Consiste na utilização de uma fonte selada e um detector de radiação [NaI(Tl)], obtendo-se o perfil de densidade unidimensional (1D) do equipamento. Nas últimas décadas, ocorreram algumas melhorias na técnica de perfilagem, tais como, na digitalização contínua das informações e nos sistemas de detecção da radiação (wireless). Novos aplicativos melhoraram a qualidade da apresentação dos resultados. Entretanto, a condição da técnica não mudou drasticamente, desde sua criação. Seu resultado é simplesmente um gráfico 1D da densidade média, em função da altura do equipamento industrial. A tecnologia inovadora proposta neste trabalho de Mestrado utiliza a reconstrução tomográfica industrial, via algoritmos iterativos derivados da ART (Algebraic Reconstruction Technique) e do MART (Multiplicative Algebraic Reconstruction Technique), para apresentar o resultado de perfilagem como uma imagem bidimensional (2D) da distribuição de densidade, ao invés de um gráfico 1D. Nitidamente, uma imagem 2D possui mais informações técnicas do equipamento em análise, permitindo um avanço na tecnologia de ensaios não destrutivos (END). Assim, muitos problemas operacionais não detectáveis em equipamentos de processos industriais podem ser descobertos e solucionados de forma on-line, usando-se o imageamento 2D. Esta tecnologia permitiu que um pedido de patente fosse depositado junto ao Instituto Nacional de Propriedade Industrial (INPI). / Dissertação (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

Orientadores: Adalene Moreira Silva, Catarina Laboure Benfica Toledo / Acompanha um mapa em folha dobrada, em bolso / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-08T09:59:00Z (GMT). No. of bitstreams: 1 Uchoa_JulianeCristinaFerreira_M.pdf: 8036278 bytes, checksum: 36166e7fe3b84772aa3a19765949fae4 (MD5) Previous issue date: 2006 / Resumo: A aquisição de dados aerogeofísicos sobre o Cinturão Mineiro, porção sul do Craton São Francisco, Minas Gerais, exibiu padrões diferentes daqueles mapeados em trabalhos de campo. Uma análise integrada de dados aerogamaespectrométricos, magnetométricos, gequímica e geológicos de campo resultaram num mapa destes padrões, destacando as relações entre as principais unidades geológicas, como suas estruturas internas e limites. O realce e análise dos dados aerogamespectrométricos a partir da classificação não supervionada apresentaram os principais litotipos, bem como suas variações internas, complementando os dados geológicos existentes. O produto principal é um mapa geológico na escala 1:100.000, onde as principais anomalias geofísicas foram checadas em campo, conferindo-se litologias, contatos geológicos e estruturas. A interpretação dos dados aerogeofísicos permitiu também a redefinição dos limites dos batólitos São Tiago e Ritápolis difícies de serem reconhecidos apenas em trabalhos de campo. A análise integrada da aerogamaespectrometria, magnetometria, geoquímica e dados de campo forneceu novas ferramentas para traçar a extensão areal destes corpos. Os padrões estruturais dentro dos batólitos trouxeram novas idéias dos mais prováveis processos de sua origem. Três corpos plutônicos foram estudados em detalhe: Ritápolis, Cassiterita e Manuel Inácio. A principal proposta foi a comparação das assinaturas geofísicas, geoquímicas e dados geológicos destes corpos. A assinatura do Ritápolis revelou uma similaridade com os outros granitóides, tais como, Itumirim e de Itutinga. Do mesmo modo, a assinatura do corpo Cassiterita é semelhante aos plútons Tabuões e Rezende Costa. O plúton Manuel Inácio pode ser mapeado nos dados geofísicos, semelhantemente aos outros corpos máficos conhecidos na região, mas devido suas baixas razões de radioelementos não foi possível correlacionar as variações de K, eTh e U com sua mineralogia. Fiinalmente, o contraste das propriedades físicas e características geoquímicas dos corpos plutônicos do Cinturão Mineiro puderam ser comparadas com dados isotópicos e geológicos adquiridos antes desta pesquisa. A integração dos dados ilustra a geração de corpos plutônicos relacionados espacial e temporalmente , contrastando diferentes fontes genéticas / Abstract: Airborne geophysical data acquired over the Mineiro Belt in the southern portion of the São Francisco Craton, Minas Gerais, Brazil display patterns not previously identified by geological field mapping. The lack of rock exposures and connections among rock formations at surface poses problems for regional geologic mapping and interpretation, which are difficult to be surpassed. An integrated analysis of gamma-ray spectrometric, magnetic, geochemical and field geological data was conducted to map and analyse these patterns, and highlight the relationships between the principal geological units, as well as their internal structures and boundaries. Enhancement and cluster analysis of the gamma-ray spectrometry data showed their usefulness in mapping subtle compositional variations in the area, which concur with and complement available geological data. The main product is a new geological map at 1:100.000 scale that was ground-checked in other to examine lithological, structural and stratigraphic relationships. The new geological map based on geophysical data enable better definition of geological units and contribute directly to more effective and efficient geological mapping. The gamma-ray spectrometry data also allowed the boundaries definition of São Tiago and Ritapolis batoliths that have not been all recognized in fied mapping and with geochemical data. The integrated analysis of gamma-ray spectrometric, magnetic, geochemical and field geological data provided a tool to map the extent of the composicional and structural patterns within the batholits and provides insigth into the most probable processes of origin. Because the subtle differences in mineralogy is associated the radioelement zoning in the plutonic bodies of Mineiro Belt may be difficult to detect in the field, enhacement and spectral analysis of gamma ray spectrometric data by unsupervised classification were applied to detected variations that are difficult to interpret from ternary images of the K, eTh and eU grids. The main results allowed the understanding of the geophysical properties and correlation with geochemical and isotopic data. Three plutonic bodies were studied in detail: Ritapólis, Cassiterita e Manuel Inácio. The main goal was define the geophysical and geochemical signatures of these bodies and extrapolate to another areas and provide new insigths to the origin of such plutons. The Ritapolis signature reveals a similarity with the Itumirim and Itutinga granitoids, while the Cassiterita signature is well mapped at the Tabões and Rezende Costa domains. The Manuel Inacio plutonic bodie can be mapped in the airborne geophysical data as well as similar bodies known at this region, but they are poor in radioelements what difficult the mapping of subtle differences in mineralogy. Finally, the physical property contrast and geochemical characteristics of the plutonic bodies of the Mineiro Belt can be well related with isotopic and geological data acquired before this research. The data integration illustrates the generation of plutonic bodies with close spatial/temporal relationships and contrasting source regions. / Mestrado / Metalogenese / Mestre em Geociências

Orientadores: Rodrigo de Souza Portugal, Adalene Moreira Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias / Made available in DSpace on 2018-08-11T23:11:38Z (GMT). No. of bitstreams: 1 Cavallaro_FranciscodeAssis_M.pdf: 3169392 bytes, checksum: 102911624b422474e306cc2cb62cdabd (MD5) Previous issue date: 2008 / Resumo: O processamento atual em gamaespectrometria necessita de novas ferramentas para auxiliar a remoção de ruídos, visto que ao final desta etapa há constatação de ruído remanescente. O ruído remanescente prejudica de forma expressiva os produtos finais. O decaimento radioativo é um processo aleatório e a estimativa de todas as medidas é governada por leis estatísticas. Os perfis de taxas de contagem são sempre "ruidosos" quando utilizados períodos curtos como um segundo para cada medida. Os filtros utilizados e, posteriormente, as correções efetuadas no processamento atual de dados gamaespectrométricos não são suficientes para remover ou diminuir consideravelmente o ruído oriundo do espectro. Dois métodos estatísticos que atuam diretamente nos dados coletados, isto é, nos espectros vêm sendo sugeridos na literatura para remover estes ruídos remanescentes: o Noise-Adjusted Singular Value Decomposition ¿ NASVD e Maximum Noise Fraction ¿ MNF. Estes métodos produzem uma redução no desvio padrão de forma significativa. Neste trabalho eles foram implementados dentro do ambiente de processamento do software OASIS MONTAJ e aplicados em uma área compreendida por dois blocos, I e II do levantamento aerogeofísico que recobre a porção oeste da Província Mineral do Tapajós - sudoeste do Estado do Pará e sudeste do Estado do Amazonas. Os dados filtrados e não-filtrados foram processados e comparados usando os coeficientes determinados pela empresa Lasa Engenharia e Prospecções S.A. Os resultados da comparação entre perfis e mapas apresentaram-se de forma promissora, pois houve um ganho na resolução dos produtos. / Abstract: The gamaespectrometry processing needs new tools to help the noise¿s removal, at the end of this step there are evidence of remaining noise; this remaining noise causes damages at the final product. The radioactive decline is a random process and the estimate of the measures is managed by statistical laws. The profiles of counting ratios are always noisy when analyzed for short periods, like a second for each measurement. Filters and corrections made in the airborne gamma-ray spectrometric data processing are not enough to remove or reduce the spectrum's noise. Two statistic methods which act directly at collected data, i.e., in the spectrum domain, the literature has been suggesting to remove such remaining noises, the Noise-Adjusted Singular Value Decomposition ¿ NASVD and Maximum Noise Fraction ¿ MNF. These methods produce a significant reduction in the standard deviation. In this work both methods were implemented in the software OASIS MONTAJ environment and applied in one area between two blocks, I and II of the airborne survey which covers the west area of Mineral Province of Tapajós ¿ southwest of Pará state and southeast of Amazonas state. The filtered and not filtered data were processed and compared using the coefficients determined by Lasa Engenharia e Prospecções S.A. The results of the comparison done, using maps and profiles showed up a promising form; therefore, these products had gained resolution. / Mestrado / Geologia e Recursos Naturais / Mestre em Geociências

La découverte du rayonnement cosmique remonte à plus d'un siècle, mais son origine est encore incertaine aujourd'hui. Divers éléments théoriques et observationnels tendent à confirmer que les vestiges de supernova (SNRs) sont à l'origine de la majeure partie du rayonnement cosmique galactique jusqu'à des énergies de ~3 PeV, voire au-delà. Mais ce paradigme requiert encore une preuve irréfutable.Lors de l'expansion d'un SNR, les particules chargées du milieu circumstellaire/interstellaire sont accélérées par l'onde de choc et peuvent alors rayonner depuis le domaine radio jusqu'aux très hautes énergies (>100 GeV). Les mécanismes d'accélération et les processus d'émission des particules ont été étudiés et modélisés au cours de cette thèse.Les instruments d'astronomie Gamma permettent de détecter les rayonnements émis par les particules accélérées au choc des SNRs. En particulier, le télescope à création de paires Fermi-LAT et le réseau de télescopes au sol à imagerie Tcherenkov atmosphérique H.E.S.S. détectent, à eux deux, des photons Gamma d'énergie comprise entre ~30 MeV et plusieurs dizaines de TeV. Au cours de cette thèse, réalisée dans le cadre de l'expérience H.E.S.S., les données observationnelles de plusieurs SNRs ont été analysées et interprétées. Les études menées ont conduit à la détection d'une des sources les plus faibles encore jamais détectée et dont l'émission Gamma est associée à l'interaction du SNR G349.7+0.2 avec un nuage moléculaire adjacent. Des limites supérieures sur les flux intégrés de nombreux SNRs ont été extraites afin de contraindre les modèles d'accélération de particules. Le SNR Puppis A présente notamment un comportement spectral inattendu, difficile à expliquer dans le cadre des modèles d'accélération de particules actuels.Un cinquième télescope, de plus grande taille, a été ajouté mi-2012 au réseau de quatre petits télescopes H.E.S.S. afin d'abaisser le seuil en énergie et d'améliorer la sensibilité du réseau. Dans ce cadre, j'ai activement participé au développement, à l'intégration et à l'analyse des données du dispositif d'étalonnage de la caméra de ce cinquième télescope. / The discovery of Cosmic Rays (CRs) dates back more than one century ago, however their origin remains unclear. There is rather convincing evidence that the bulk of Galactic CRs, up to ~3 PeV, and possibly beyond, is accelerated in supernova remnants (SNRs). However this paradigm still needs a conclusive proof. While the SNR expands, charged particles from the circumstellar/interstellar medium are accelerated at the SNR shock wave and radiate from radio to very high energies (>100 GeV). Particles acceleration and broad band radiation mechanism were studied and modelled during this PhD. $gamma$-ray astronomy instruments enable to detect radiation from particles accelerated at the SNR shock wave. In particular the pair creation telescope Fermi-LAT and the array of imaging atmospheric Cherenkov telescopes H.E.S.S., enable together to detect Gamma-ray photons in the ~30 MeV-30 TeV energy range. As a member of the H.E.S.S. collaboration, I analysed and interpreted observational data from several Galactic SNRs. These studies led to the discovery of one of the faintest sources ever detected whose Gamma-ray emission is associated with the interaction of the SNR G349.7+02 with an adjacent molecular cloud. Upper limits on the integrated flux of many SNRs were extracted in order to constrain models of particle acceleration. In particular, the SNR Puppis A shows an unexpected spectral behavior difficult to explain with current models. A fifth bigger telescope was added mid 2012 to the H.E.S.S. array of four small telescopes to lower the energy threshold and to improve the sensitivity of the array. In this context I actively participated to the development, integration end data analysis of the calibration hardware of the camera of this fifth telescope.

[pt] Para estabelecer com exatidão as curvas em eficiência de detectores a germânio, usam-se radionuclídeos que possuem decaimento complexo, como o 152 Eu e 133 Ba. Porém, por possuírem poucas linhas gama de boa intensidade e irregularmente distribuídas no espectro, esses radionuclídeos não podem ser usados sozinhos. Para superar tais dificuldades, o 166m Ho mostra-se conveniente como padrão único destinado à calibração em eficiência dos espectrômetros a germânio, pois decai por emissão b - , com emissões subseqüentes de 40 linhas gama intensas e bem distribuídas entre 80 e 1500 keV. Além disso, sua longa meia-vida (1200 anos) e raios X característicos entre 40 e 50 keV, o tornam um padrão excelente para calibração de detectores de germânio. É preciso, no entanto, conhecer com exatidão as probabilidades de emissão de fótons de suas principais linhas, uma vez que a literatura tem apresentado estes valores com discrepâncias. Neste trabalho é proposta uma metodologia para determinar, com rigor metrológico, a probabilidade de emissão de suas principais linhas, por meio do uso combinado de espectrometria gama e técnicas de coincidência (4pb-g ). Os resultados experimentais apresentaram-se convergentes em relação aos dados de outros autores, com incertezas menores ou compatíveis. / [en] The efficiency and calibration curves as function of gamma- ray energy for a germanium detector are usually established by using many standard gamma-ray sources of radionuclides decaying with few gamma rays or radionuclides having complex decay scheme, as 152 Eu or 133 Ba. But these radionuclides cannot be used alone, because they have a few gamma lines with high intensity and these lines have a irregular distribution in the energy spectrum. 166m Ho is found to be a convenient single source for such calibration, because it decays by b - with subsequent emission of about 40 strong and well distributed gamma lines between 80 and 1500 keV. Moreover, its long half - life (1200 years) and X-rays characteristics between 40 and 50 keV makes it a good standard for calibration of germanium detectors. However, it is necessary to know with accuracy and precision the gamma ray intensities of their main lines, due to the fact that literature has showed discrepant values. Then, a methodology to determine the emission probability of its main lines is proposed by means of combined use of gamma spectrometry and coincidence 4pb - g techniques. The experimental results show consistence to the others authors, with lower or compatible uncertainties. / [es] Para estabelecer con exactitud las curvas en eficiencia de detectores la germánio, se utilizan radionuclídeos que poseen decaimiento complejo, como el 152 Eu y 133 Ba. Sin embargo, como poseen pocas líneas gama de buena intensidad y irregularmente distribuidas en el espectro, esos radionúcleos no pueden ser usados separadamente. Para superar tales dificuldades, el 166m Ho muestra se conveniente como padrón único destinado a la calibración en eficiencia de los espectrómetros la germánio, pues decae por emisión b , con emisiones subsecuentes de 40 líneas gama intensas y bien distribuidas entre 80 y 1500 keV. Además, su larga media vida (1200 anos) y rayos X característicos entre 40 y 50 keV, el tornan un padrón excelente para calibración de detectores de germanio. Es preciso conocer con exactitud las probabilidades de emisión de fóptons de sus principales líneas, una vez que la literatura ha presentado estos valores con discrepancias. En este trabajo se propone una metodología para determinar, con rigor metrológico, la probabilidad de emisión de sus principales líneas, por medio del uso combinado de espectrometría gama y técnicas de coincidencia (4pb g ). Los resultados experimentales presentaran se convergentes en relación a los datos de otros autores, con incertezas menores o compatibles.

Magister Scientiae - MSc / In this study, two methods of analysing activity concentrations of natural radionuclides (U, Th and K) in soil are critically compared. These are the Window Analysis (WA) and Full Spectrum Analysis (FSA). In the usual WA method, the activity concentrations are determined from the net counts of the windows set around individual γ-ray peaks associated with the decay of U, Th and K. In the FSA method, the full energy spectrum is considered and the measured spectrum is described as the sum of the three standard spectra (associated with U, Th and K, respectively), each multiplied by an unknown concentration. The concentrations are determined from the FSA and correspond to the activity concentrations of U, Th and K in the soil. The standard spectra derived from separate calibration measurements using the HPGe detector, represents the response of the HPGe to a Marinelli sample beaker containing an activity concentration of 1 Bq/kg. / South Africa

Philosophiae Doctor - PhD / Lying in a rapidly-changing transitional region between nuclei that may behave as spherical vibrators (N ≤ 88) or good rotors (N ≥ 92), the N = 90 isotones present a unique testing ground where new nuclear collective phenomena may be uncovered. As part of a general investigation of collective structures and the coupling of single-particle states to these structures, the 150Sm(12C,4nγγ) and 150Sm(13C,4nγγ) reactions at a beam energy of Elab = 65 MeV were used to study the low and medium spin structure of 158,159Er nuclei below spin 20~. The γ-γ coincidence events were detected in the nine escape-suppressed HPGe Clover detectors using the AFRODITE γ-ray spectrometer at the iThemba Laboratory for Accelerator Based Sciences. DCO ratios and γ-ray polarization measurements were used to establish the spins and parities of newly observed and confirm previously established rotational bands. The observed bands will be discussed in terms of both traditional quadrupole rotational-vibration models and recent predictions of octupole correlations in the N = 90 isotones and neighbouring nuclei. The data obtained will be compared with the spectroscopic systematics of neighbouring nuclei.

Les sursauts gamma se divisent entre sursauts courts, issus de la coalescence de deux objets compacts, et sursauts longs, issus de l'effondrement d'une étoile très massive de type Wolf-Rayet. Ce phénomène cataclysmique produit un jet ultra-relativiste. La dissipation de l'énergie au sein de ce jet est à l'origine d'une bouffée de photons gamma (keV-GeV) d'une durée moyenne de 10 s que l'on nomme émission prompte. Elle est suivie d'une phase d'émission rémanente détectable en X, en optique et en radio qui est visible de quelques secondes après le sursauts à quelques jours voir semaines et provient de la dissipation de l'énergie du jet dans le milieu environnant. Il s'agit des événements transitoires les plus lumineux que nous connaissons ce qui permet de les détecter jusqu'à des valeurs de décalage cosmologique (redshift) de l'ordre de 8-9. Cela permet l'exploration du diagramme de Hubble à grand redshift qui reste encore mal connu. Mais pour cela, il est nécessaire de standardiser ces sources astrophysiques afin de calibrer leur luminosité. Diverses relations, liant la luminosité des sursauts gamma à un paramètre indépendant de la cosmologie, ont été mises en évidence permettant de transformer les sursauts en " chandelles standards ". Au cours de cette thèse, nous avons étudié ces relations afin d'apporter un éclairage nouveau sur la façon dont elles sont affectées par divers effets de sélection instrumentaux. Les relations spectrales lient la luminosité isotropique ou l'énergie isotropique à l'énergie du maximum spectral de l'émission prompte. Nous avons montré que la combinaison de deux effets de sélection (détection puis mesure du redshift) permettait d'expliquer les contradictions entre les études reposant sur les sursauts avec redshift et celles incluant les sursauts sans redshift. Cela a conduit à la mise en évidence d'un lien entre l'émission prompte en gamma et l'émission rémanente en optique. Nous nous sommes également intéressé à l'une des relations temporelles, celle reliant Liso au délai spectral. Ce paramètre correspond à la différence entre le temps d'arrivée des photons de hautes et de basses énergies. Après avoir développé notre propre méthode de calcul de cette quantité, nous avons obtenu des résultats intéressants sur les distributions de ce paramètre et son lien avec l'évolution spectrale au sein des sursauts gamma. Nous avons également mis en évidence l'existence d'effets de sélection impactant cette relation et compromettant son usage pour la cosmologie. Plus généralement, cette thèse a permis de mettre en évidence la complexité de la standardisation des sursauts gamma qui ne peut être faites de manière aussi simple que celle utilisée jusqu'à présent. Nous avons montré qu'une étude détaillée des effets de sélection qui affectent ces relations de standardisation est un préalable indispensable avant toute utilisation de ces dernières à des fins cosmologiques. / GRBs are divided between short bursts, resulting from the coalescence of two compact objects, and long bursts, resulting from the collapse of a very massive star (Wolf-Rayet type). This cataclysmic phenomenon produces an ultra-relativistic jet. Energy dissipation in this jet produces flashes of gamma photons (keV-GeV) with an average duration of 10 seconds which is called prompt emission. It is followed by a detectable afterglow phase in X, optical and radio band which is visible from a few seconds after the bursts to several days or weeks and results from the dissipation of the energy contained in the jet into the surrounding medium. They are the most luminous transient events that we know, which can be detected up to redshifts of about 8-9. Being so bright, GRBs may allow the exploration of the Hubble diagram at high redshift, which is still poorly understood. To do this, it is however necessary to standardize these astrophysical sources and calibrate their brightness. Various relationships linking the intrinsic luminosity of GRBs with a parameter independent from cosmology have been highlighted allowing GRBs standardization. To achieve this goal, it is necessary to assess whether the observed correlations represent an intrinsic property of GRBs. In this thesis, we study selection effects to understand their impact on several relations which have been used to standardize GRBs. Spectral relationships connect the isotropic brightness or isotropic energy, and the peak energy of the prompt emission. We show that a combination of two selection effects, respectively associated with the GRB detection and the measure of their redshift, explains the contradiction between studies based on GRBs with a redshift and studies based on larger samples of GRBs without a redshift. Our study led us to discover a link between the prompt gamma emission and the optical afterglow that is a first step to understand the link between these two phases of the gamma-ray burst emission. Among the second category of relations, we focused on the relation between the luminosity and the spectral lag of the prompt emission. This parameter corresponds to the difference between the times of arrival of GRB photons at high and low energies. We developed our own method for the measure of the spectral lag, which led us to discuss the distribution of this parameter and its relationship to the spectral evolution within GRBs. We also confirmed the existence of selection effect affecting this relationship and compromising its use for cosmology. This thesis highlights the strong impact of observational selection effects on the relations which have been proposed for GRB standardization. We conclude that the study of selection effects is essential to understand if the relations proposed for the standardization of GRBs are intrinsic or due to selection effects, and if they can be used for cosmological purposes.

More accurate knowledge of gamma-ray heating in nuclear reactors has beenlisted as a high priority request by the NEA [23]. In response to this the SpecTrometerfor Exotic Fission Fragments (STEFF), a 2-velocity, 2-energy spectrometer assembledby the Manchester Fission Group has been used to take measurements ofprompt gamma-rays from thermal fission of U-235. Through the procedures discussed,the average total gamma-ray energy and average multiplicity were determined to be8.40 +/- 0.26 MeV and 7.74 +/- 0.12, respectively. The single energy spectrum for eachindividual detector has been determined as well as the total energy distribution. A new parallel plate avalanche counter has been tested for its potential to improvethe timing resolution of the current STEFF stop detector. The timing resolution ofthe new detector is found to be 337 ps, an improvement of 75 % on the previous stopdetector. The pulse shapes created by a fission fragment in an ionisation chamber havebeen investigated. The relationship with fragment atomic number has been tested byemploying the Lohengrin spectrometer to separate fragments by mass so that theirindividual pulse shapes can be studied. Evaluation work has been performed at the NNL, Cumbria, under the supervisionof Dr Robert Mills. Experimental data determined from the spontaneous fission ofCf-252 has been extracted and evaluation techniques performed upon it so that thedata can be considered for inclusion within an evaluated nuclear database.

Orientador: Carlos Roberto de Souza Filho / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Geociências / Made available in DSpace on 2018-08-26T21:42:34Z (GMT). No. of bitstreams: 1 Magalhaes_LuciolaAlves_D.pdf: 18006745 bytes, checksum: e07ddabc39328486a6c0a93b03caf806 (MD5) Previous issue date: 2015 / Resumo: Os reservatórios de petróleo são insuficientemente selados, permitindo escapes de fluidos que atingem a superfície e formam exsudações. As exsudações de hidrocarbonetos (HCs) gasosos são, muitas vezes, visualmente imperceptíveis. Porém, alteram o pH e o Eh do meio, favorecem a transformação de fases minerais (causando anomalias mineralógicas e geofísicas) e induzem estresse na vegetação. Dados e técnicas de processamento espectral são úteis para mapear tais alterações e auxiliar na descoberta de novas acumulações de petróleo. O objetivo desta pesquisa foi investigar alterações dessa natureza nas bacias continentais brasileiras, considerando cenários desenvolvidos sob diferentes regimes climáticos e contextos geológicos distintos. As regiões do Diápiro do Cinzento/BA e do Remanso do Fogo/MG, onde são registradas exsudações naturais de óleo e gás, respectivamente, foram selecionadas como estudos de caso. Essas áreas estão situadas nas bacias sedimentares do Recôncavo/BA e do São Francisco/MG. A Bacia do Recôncavo é a segunda bacia terrestre brasileira em volume de produção de petróleo. Apesar de seu elevado número de campos em produção, ainda conta com diversos trabalhos exploratórios para a descoberta de novos plays. A Bacia do São Francisco, por sua vez, encontra-se em fase de exploração e diversos poços recentemente perfurados mostraram indícios da existência de gás. Dados de gasometria de solos, dados radiométricos aéreos e terrestres, dados de espectroscopia de refletância de solos, rochas e vegetação, dados de difração de raios-X e imagens multiespectrais dos sensores ASTER e RapidEye e hiperespectrais do sensor ProSpecTIR-VS foram utilizados para mapear essas exsudações. Como resultado da análise da composição mineralógica dos solos do Remanso do Fogo, foi possível identificar as microexsudações com base na variação da profundidade das bandas de absorção da caulinita e dos óxidos/hidróxidos de ferro. Anomalias na vegetação foram mapeadas a partir das imagens ASTER e ProSpecTIR-VS. Os dados radiométricos terrestres indicam perda de potássio e enriquecimento em urânio nas áreas próximas às microexsudações. No Diápiro do Cinzento, a degradação do HC gerou um ambiente ácido e rico em sulfato, proporcionando a formação da assembléia jarosita-pirita-goetita - minerais identificados a partir de dados de espectroscopia de reflectância e de difração de raios-X. Nas porções mais distais da zona de exsudação, a hematita e a goetita são as fases mais estáveis. As imagens multiespectrais do RapidEye foram eficazes no mapeamento dos minerais relacionados à esses ambientes com pH distintos no Diápiro. Dentre as principais contribuições desta pesquisa, destaca-se o avanço no conhecimento das alterações mineralógicas induzidas pelas exsudações de HCs líquidos e gasosos em bacias sedimentares brasileiras submetidas a diferentes regimes tectônicos, condicionantes das exsudações. Adicionalmente, demonstrou-se a importância da utilização de dados adquiridos sob diferentes resoluções espaciais e espectrais no mapeamento do fenômeno que, conforme ficou demonstrado, ocorre de forma restrita, enquanto seeps individuais. O conjunto dos resultados da pesquisa revelou novos parâmetros exploratórios que podem ser testados e utilizados para a prospecção petrolífera em território nacional / Abstract: Petroleum reservoirs are not entirely sealed, thus allowing leaks of lighter hydrocarbons (HC) to reach the surface and form microseepages. Gas microseeps are usually undetectable by the naked eye. However, the HC biodegradation changes the pH and Eh of the environment, induces alterations in geological materials (resulting in mineralogical and geophysical anomalies) and causes stress in vegetation. Remote sensing and radiometric data are potentially useful to identify these alterations and to discover new petroleum plays. The goal of this research was to investigate the mineralogical changes induced by oil and gas seeps in Brazilian sedimentary basins under different climatic conditions and geological settings. The Diápiro do Cinzento (Bahia (BA) State) and Remanso do Fogo (Minas Gerais (MG) State) are considered archetype areas in Brazil for oil and gas seeps research, respectively. These areas are located in the Recôncavo (BA) and São Francisco (MG) sedimentary basins. The Recôncavo basin hosts the second largest oil producing fields among onshore basins in Brazil. Despite the large number of productive brownfields, the basin is still the focus of exploration activities. In contrast, the São Francisco Basin is yet in the exploration stage. Several wells recently drilled in greenfields in the basin showed evidences of gas. Gasometric data, airborne and terrestrial radiometric data, reflectance spectroscopy data of soils, rocks and vegetation, X-ray diffraction data, ASTER and RapidEye multispectral imagery and ProspecTIR-VS hyperspectral imagery were employed in the research. Continuum-removed VNIR and SWIR spectra of soils in the Remanso do Fogo area were used to vectorize the location of microseeps based on the absorption bands of kaolinite and iron oxides/hydroxides. Vegetation stress was mapped using both ASTER multispectral and ProSpecTIR-VS hyperspectral data. Ground gammaspectrometric data collected around proven microseeps show loss of potassium and enrichment of uranium, as verified in several sites. In the Diápiro do Cinzento, the mineralogical assemblage of jarosite-pyrite-goethite is intrinsically related to hydrocarbon degradation. Such minerals, which indicate acidic and sulfate-rich conditions, were promptly detected by reflectance spectroscopy and X-ray diffraction. Far from the macroseepage zone, iron minerals such as hematite and goethite predominate. RapidEye multispectral images were effective for mapping these minerals remotely in the Diápiro do Cinzento, reflecting environments with different pH conditions. The main contribution of this research was to improve the knowledge of mineralogical changes induced by oil and gas hydrocarbon seeps in Brazilian sedimentary basins formed under different tectonic settings. Additionally, this research demonstrated the usefulness of remote sensing data yielded at various spectral and spatial resolutions to map the seepage phenomena. Evidences at multiple scales show that individual seeps can be more spatially restricted that previously envisaged and display specific mineralogical and geobotanic features in a small area. The overall results of the research offer new perspectives for petroleum exploration in Brazilian offshore basins / Doutorado / Geologia e Recursos Naturais / Doutora em Ciências