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Dissertations / Theses on the topic 'Gamma spectrometry'

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Published: 4 June 2021
Last updated: 26 January 2023

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1

Tyler, Andrew Nicholas. "Environmental influences on gamma ray spectrometry." Thesis, University of Glasgow, 1994. http://theses.gla.ac.uk/4893/.

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Spatially representative sampling of both natural and anthropogenic deposits in the environment is limited by their inherent heterogenic distribution. This problem is compounded when trying to relate ground measurements which are spatially restricted to remote sensing observations which are not. This work examined these widely experienced problems in the context of the measurement of natural (K, U and Th) and anthropogenic ( 137Cs and ' 34Cs) radioactivity through the three techniques of soil sampling with laboratory based gamma ray spectrometry, in-situ gamma ray spectrometry, and airborne gamma ray spectrometry. These three methods were applied systematically to estimate the radioactivity across a tight geometry valley in Renfrewshire. Activity estimates from field based and airborne gamma spectrometry were compared with each other and with the results of high resolution gamma spectrometry of soil samples to examine the relationship between each method under variable topographic conditions. These results demonstrated that the distribution, and post depositional migration, of activity had important influences on all measurement techniques, and affected the ability to make comparisons between them. Further detailed studies were then conducted to examine these influences. The effects of variations in soil composition and characteristics on environmental gamma ray spectrometry were evaluated by calculation and experimental determination. Corrections to standard laboratory gamma spectrometric procedures were developed to improve systematic precisio:i. These investigations also reviewed soil sampling depth for direct effective comparison with in-situ gamma spectrometry. The effects of small scale sampling errors on activity estimates were demonstrated to have a quantifiable influence on the precision of activity estimation. Lateral variability of activity distribution of natural radioactivity and anthropogenic radioactivity deposited both from the atmosphere and from marine sources has been studied in detail at a number of sites. The extent of variability depends on the nature of activity, its deposition mode and local environmental characteristics. Spatial variability represents an important constraint on the interpretation of activity estimates derived from all methods examined, and on comparisons between them. Statistically representative sampling plans were developed and applied to enable spatial comparisons to be made between soil sample derived activity estimates and in-situ and remotely sensed observations. The influence of the vertical activity distribution on in-situ and airborne measurements has been recognised as an important variable affecting calibration. The use of the information from the scattered gamma ray spectrum to quantify and correct for source burial effects was examined in a series of modelling experiments. A relationship between 'Cs source burial and forward scattering was determined and subsequently applied to a salt marsh environment which showed pronounced subsurface maxima. A spectrally derived calibration correction coefficient was shown to account for variations in source burial across a single site. This provides a potential means for surmounting one of the principal limitations of in-situ gamma spectrometry. As a result of this work it has been possible to account for important environmental factors which affect gamma ray spectrometry in the laboratory, in the field and from aircraft. This has led to the development of sound methodology for comparison between sampling, field based and remote sensing techniques.
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2

Brown, Nathaniel J. "Studies in the mass 160 decay chain. gamma-ray and conversion electron spectroscopy for the 160lu-160yb, 160yb-160tm, 160tm-160er decay schemes." Diss., Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/33956.

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Excited states in the transitional nucleus 160Yb have been studied using gamma-ray and conversion electron spectroscopy following the beta+/EC decay of 160Lu. Excited states in the nuclei 160Tm and 160Er have been studied following the beta+/EC decay of 160Yb and 160Tm, respectively. The data for the present study were obtained at TRIUMF in Vancouver, Canada at the ISAC-1 facility through radioactive sources moved into the combination of the 8pi gamma-ray spectrometer array and the Pentagonal Array for Conversion Electron Spectroscopy (PACES). Analysis of gamma-ray gated gamma-ray, gamma-ray gated conversion electron and conversion electron gated gamma-ray spectra resulted in the discovery of a new first excited state and the establishment of a level scheme for 160Tm which differs from the one adopted; as well as a test of the rotational characteristics of 160Er with intensity comparisons to both the spin-5 beta-decaying isomer study of by Singh et al. and the spin-parity 1- beta decay study of by Strusny et al. and Bykov et al.
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3

Camp, Brunés Anna. "Improvement of early warning monitoring using gamma spectrometry." Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/458379.

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The present thesis is focused on the improvement of radiological surveillance networks using gamma spectrometry. Tipically they are equipped with gamma dose rate monitors, while they do not have gamma spectrometry monitors. These measure the effects of gamma radiation, but do not provide any nuclide-specific information. Nowadays new materials have been developed in the spectrometry research field and the implementation of gamma spectrometry detectors is being actively considered in European gamma-dose stations (more than 5000). In this thesis the lanthanum bromide, LaBr3(Ce), detector has been selected as the reference instrument to study the possibility of installing it in early warning networks. The reasons for its choice were its resolution, which improves from 7 % to 3 % at 662 keV, its availability and the fact that these detectors are already being used at institutions such as STUK, the nuclear safety authority in Finland. Selected monitors have been characterized by irradiation at a reference laboratory at the Institute of Energy Technologies (INTE). Furthermore, the study of their inherent background and the influence of cosmic radiation have been investigated by means of exposures in lakes, underground laboratories and the use of Monte Carlo (MC) simulations. In addition to its main function, gamma spectroscopy, these detectors allow the possibility of calculating values of ambient dose equivalent H*(10). In this thesis two different methods have been developed and applied to spectra measured using LaBr3(Ce) crystals in long-term measurements and intercomparison campaigns, the stripping method and the conversion coefficients method. The first is based on obtaining the external flux that reaches the monitor and involves the subtraction of all partial absorptions produced by scatterings in the monitor itself. This methodology, which has been already studied and usually applied to HPGe detectors, proved that it can also offer good results in LaBr3(Ce) detectors. The second methodology is based on splitting the spectra into several energy regions, and a coefficient to "convert" from measured counts to H *(10) values for each region is defined. Results obtained have been compared with classical dose rate monitor values. The long-term measurements were performed at surveillance stations in Barcelona and Madrid. Since, fortunately, there were no radiological emergencies during research for this thesis, H*(10) diurnal and seasonal variations at these stations are studied from the viewpoint of the influence of cosmic radiation and variations of 222Rn daughter concentration. Intercomparison campaigns were performed at Physikalisch-Technische Bundesanstalt (PTB) facilities to study both detector sensibility and the accuracy of H*(10) calculated values. Use of new technological advances in the determination of high levels of H*(10) led us to study the viability of installing gamma radiation detectors on an unmanned aerial vehicle. In this thesis a drone prototype has been developed which uses a 3'' x 3'' NaI installed in an RPAS helicopter. The first flights took place at different altitudes and over a pond in order to study detector sensitivity. Although the prototype it is still at an initial stage and more flights are required, preliminary results obtained are promising, showing that the system is able to detect variations in terrestrial radioactivity.
La present tesis se centra en la millora de les estacions de radiovigilància ambiental a partir de l'ús de l'espectrometria gamma. Típicament aquestes estacions estan equipades amb monitors de mesura de dosis, però no disposen d'equips d'espectrometria. Això significa que es poden prendre mesures dels efectes de la radiació, la dosis, però no es pot obtenir informació sobre els radionúclids que produeixen aquesta radiació. Avui en dia s'han desenvolupat nous materials en el camp de l'espectrometria i la implementació d'aquest tipus de detectors s'està considerant activament per part de les estacions de radiovigilància europees (més de 5000). A la tesis el detector de bromur de lantà, LaBr3(Ce), s'ha seleccionat com a instrument de referència per estudiar la viabilitat de ser instal·lat a les estacions anomenades "early warning", és a dir, que està previst donin el primer avís en cas d'emergència radiològica. Les raons d'escollir aquest detector són la seva resolució, que millora del 7 % al 3 % als 662 keV, la seva disponibilitat i el fet que aquests detectors ja s'han començat a utilitzar per institucions com l'STUK, l'autoritat de seguretat nuclear a Finlàndia. Els monitors seleccionats s'han caracteritzat mitjançant irradiacions al laboratori de referència de l'Institut de Tècniques Energètiques (INTE). També s'han realitzat estudis sobre la seva contaminació interna i la influència de la radiació còsmica a través de mesures en llacs, laboratoris subterranis i l'ús de simulacions Monte Carlo (MC). A més de la seva principal funcionalitat, l'espectrometria gamma, també tenim la possibilitat de calcular valors de dosis equivalent ambiental H*(10) a partir dels espectres registrats. En aquesta tesis dues metodologies diferents s'han desenvolupat i aplicat als espectres mesurats amb cristalls de LaBr3(Ce), en mesures de llarga durada i en campanyes d'intercomparacions: la metodologia de l'"stripping" i la de "conversion coefficients". La primera es basa en obtenir el flux real que arriba al detector i implica restar totes aquelles absorcions parcials que es produeixen per "scatterings" en el monitor mateix. Aquesta metodologia, que ja s'ha estudiat i usualment s'aplicava a detectors de HPGe, ha mostrat bons resultats també amb els detectors de LaBr3(Ce). La segona metodologia es basa en dividir l'espectre en diferents regions energètiques i definir per cadascuna d'elles un coeficient per passar de número de comptes mesurats a valors de H*(10). Els resultats obtinguts amb els dos mètodes s'han comparat amb els que proporcionaria un monitor de taxa de dosis. Les mesures de llarga durada es van dur a terme en estacions de vigilància de Barcelona i Madrid. Com que, afortunadament, no va haver-hi cap emergència radiològica mentre s'estava realitzant la tesis, les variacions diürnes i estacionals de H*(10) en aquestes estacions s'han estudiat des del punt de vista de la influència de la radiació còsmica i les variacions en la concentració dels descendents del 222Rn. Les campanyes d'intercomparació es van dur a terme a les instal·lacions del Physikalisch-Technische Bundesanstalt (PTB) per estudiar tant la sensibilitat com la precisió dels valors de H*(10) calculats. L'ús dels nous avenços tecnològics en la determinació d'alts nivells de H*(10) ens han permès estudiar la viabilitat d'instal·lar detectors gamma en vehicles aeris no tripulats. En aquesta tesis s'ha desenvolupat un prototip de dron que utilitza un detector de 3" x 3" de NaI instal·lat en un helicòpter RPAS. Els primers vols es van realitzar a diferents alçades i sobrevolant un estany per tal de veure la seva sensibilitat. Malgrat que el prototip encara es troba en una fase inicial i caldran molts més vols de prova, els resultats inicials han estat prometedors, ja que han mostrat que el sistema és sensible a les variacions de la radioactivitat natural.
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4

Boson, Jonas. "Improving accuracy of in situ gamma-ray spectrometry." Doctoral thesis, Umeå : Umeå University, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-1805.

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5

Xu, Jiaxin. "Development of analysis tools for gamma-ray spectrometry." Electronic Thesis or Diss., université Paris-Saclay, 2020. http://www.theses.fr/2020UPASG030.

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La spectrométrie gamma est une des techniques principales pour la mesure de la radioactivité, qui permet d'identifier et quantifier les radionucléides. L'objectif de la thèse est de développer de nouvelles méthodes d’analyse des spectres gamma afin d'améliorer les limites de détection. Dans ce contexte, la première contribution est la proposition de nouvelle approches statistiques pour l'estimation des activités en spectrométrie gamma par le démélange spectral, qui consiste à décomposer un spectre gamma mesuré en spectres individuels des radionucléides. Contrairement aux méthodes standard, cette approche permet de traiter un spectre gamma dans sa globalité et prendre en compte la statistique Poisson du processus de détection. En modélisant l'estimation des activités comme un problème inverse sous la contrainte de non-négativité, le démélange spectral parcimonieuse est étudié pour estimer conjointement l'ensemble des radionucléides actifs et leurs activités. La deuxième contribution est l'utilisation métrologique du démélange spectral étudié, qui nécessite en plus l'évaluation des limites caractéristiques pour la prise de décision et l'étalonnage des instruments pour l'analyse quantitative
Gamma-ray spectrometry is one of the main techniques used for the measurement of radioactivity, which allows identifying and quantifying radionuclides. The objective of this thesis is to develop new spectrum analysis methods to improve the detection limits. In this context, the first contribution is investigating the activity estimation in gamma-ray spectrometry with spectral unmixing, which decomposes a measured spectrum into individual radionuclides' spectra. Contrary to standard methods, this approach allows accounting for the full spectrum analysis of a gamma-ray spectrum and the Poisson statistics underlying the detection process. By formulating the activity estimation as an inverse problem under non-negativity constraint, the sparse spectral unmixing is investigated to estimate the subset of active radionuclides and their activities jointly. The second contribution is the metrological use of the investigated spectral unmixing method, which further necessitates the evaluation of characteristic limits for decision making purposes and the instruments' calibration for quantitative analysis
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6

Hernández, Suárez Francisco Javier. "Optimisation of environmental gamma spectrometry using Monte Carlo methods." Doctoral thesis, Uppsala University, Department of Physics, 2002. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-2672.

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Dissertation in Environmental Physics to be publicly examined in Häggsalen (Ångström Laboratory), Uppsala University, on Friday, November 8, 2002 at 10:00 am for the degree of doctor of philosophy in Physics. The examination will be conducted in English.

Gamma spectrometry is one of the tools commonly used for the measurement of various environmental radionuclides. Simultaneous determination of the absolute activity of gamma emitting radiotracers in a wide range of environmental matrices and fractions necessitates proper and accurate evaluation of the sample-to-detector efficiency. Several radiotracers require, in addition, the use of sub-routines for self-absorption corrections.

Gamma spectrometry is an important and elegant tool for assessing environmental changes. Optimisation of ultra low-level gamma spectrometry for reliable assessment of such changes requires harmonisation of laboratory needs with sampling and site conditions.

Different aspects of the calculation of sample-to-detector efficiencies using empirical and Monte Carlo approaches are discussed here, including the uncertainties related to the simulation of the performance of different HPGe detectors and the effects of the incomplete collection of charges in Ge-crystals. Various simulation codes for the computation of peak efficiencies in planar and well Ge-detectors have been developed from scratch. The results of the simulations have been tested against experimental data and compared to other simulation results obtained with the Monte Carlo N-Particle code (MCNP). The construction of calibration sources with improved absorption and collimation characteristics have been, also, described in this work. These sources have been especially designed for the efficiency calibration of Ge-detectors at energies below 100 keV.

Flexible, fully tested and prototype approaches for the evaluation of self-absorption corrections, based on Monte Carlo simulations, are described. Special consideration is given to the problems related to the sample's variability in size, density and composition. Several examples of the absolute and simultaneous determination of environmental multitracers which benefited from self-absorption corrections and the optimised efficiency calibration algorithms are, also, presented and discussed. These examples include, among other things, a comprehensive analysis of the gamma spectrometry of 234Th in a wide range of matrices and the speciation of several radionuclides in sediments from a hard-water lake.

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7

Varley, A. L. "Bridging the capability gap in environmental gamma-ray spectrometry." Thesis, University of Stirling, 2015. http://hdl.handle.net/1893/23320.

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Environmental gamma-ray spectroscopy provides a powerful tool that can be used in environmental monitoring given that it offers a compromise between measurement time and accuracy allowing for large areas to be surveyed quickly and relatively inexpensively. Depending on monitoring objectives, spectral information can then be analysed in real-time or post survey to characterise contamination and identify potential anomalies. Smaller volume detectors are of particular worth to environmental surveys as they can be operated in the most demanding environments. However, difficulties are encountered in the selection of an appropriate detector that is robust enough for environmental surveying yet still provides a high quality signal. Furthermore, shortcomings remain with methods employed for robust spectral processing since a number of complexities need to be overcome including: the non-linearity in detector response with source burial depth, large counting uncertainties, accounting for the heterogeneity in the natural background and unreliable methods for detector calibration. This thesis aimed to investigate the application of machine learning algorithms to environmental gamma-ray spectroscopy data to identify changes in spectral shape within large Monte Carlo calibration libraries to estimate source characteristics for unseen field results. Additionally, a 71 × 71 mm lanthanum bromide detector was tested alongside a conventional 71 × 71 mm sodium iodide to assess whether its higher energy efficiency and resolution could make it more reliable in handheld surveys. The research presented in this thesis demonstrates that machine learning algorithms could be successfully applied to noisy spectra to produce valuable source estimates. Of note, were the novel characterisation estimates made on borehole and handheld detector measurements taken from land historically contaminated with 226Ra. Through a novel combination of noise suppression and neural networks the burial depth, activity and source extent of contamination was estimated and mapped. Furthermore, it was demonstrated that Machine Learning techniques could be operated in real-time to identify hazardous 226Ra containing hot particles with much greater confidence than current deterministic approaches such as the gross counting algorithm. It was concluded that remediation of 226Ra contaminated legacy sites could be greatly improved using the methods described in this thesis. Finally, Neural Networks were also applied to estimate the activity distribution of 137Cs, derived from the nuclear industry, in an estuarine environment. Findings demonstrated the method to be theoretically sound, but practically inconclusive, given that much of the contamination at the site was buried beyond the detection limits of the method. It was generally concluded that the noise posed by intrinsic counts in the 71 × 71 mm lanthanum bromide was too substantial to make any significant improvements over a comparable sodium iodide in contamination characterisation using 1 second counts.
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8

Hutchinson, Jesson. "Handheld gamma-ray spectrometry for assaying radioactive materials in lungs." Thesis, Available online, Georgia Institute of Technology, 2005, 2005. http://etd.gatech.edu/theses/available/etd-11102005-164303/.

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9

Zhang, Weihua. "Studies on anticoincidence gamma-ray spectrometry in neutron activation analysis." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq24768.pdf.

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10

Mubashir, Hassan. "Installation and optimization of a gamma spectrometry system in anticoincidence." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2021.

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The work covered by this thesis was carried out at the Brasimone ENEA Research Centre, the National Agency for New Technologies, Energy and Sustainable Economic Development, with the aim of optimising a gamma spectrometry system in anticoincidence for the detection of noble gases, in particular the radioactive isotopes of xenon 131mXe, 133Xe, 133mXe and 135Xe. The laboratory of the ENEA Research Center of Brasimone, where the experimental apparatus is found to carry out the measurements of 131mXe, 133Xe, 133mXe and 135Xe, collaborates constantly with the monitoring network and is able to provide, if necessary, data and analysis on noble gases. The signals produced by the interaction of cosmic rays that manage to pass the screen have been recognized as the main cause of the increase of the detector background because they give rise to the Compton continuum and, as a result, they increase the value of detectable MDA. For this reason, a system in anticoincidence has been developed through the use of two plastic scintillators, placed over the shielding of the Hpge detector, which sends pulses recording within a gate located in the germanium multichannel analyzer: at the time the signal arrives from the scintillator, the gate blocks data acquisition to avoid recording pulses generated by cosmic radiation. For both configurations of the system, therefore, both with the anti-coincidence apparatus inactive and in operation, energy, FWHM and efficiency calibrations had to be carried out using a certified multi-peak source. The solution proposed, in conclusion of the thesis, to eliminate any electronic interference with the efficiency of the detector provides for the replacement of the current electronic apparatus with a new fully digitized, made by the company CAEN, Nuclear Electronic Construction Equipment.
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11

FARIAS, Emerson Emiliano Gualberto de. "Determinação de 238U e 232Th em amostras ambientais por espectrometrias alfa e gama." Universidade Federal de Pernambuco, 2011. https://repositorio.ufpe.br/handle/123456789/18283.

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Nos últimos anos tem-se observado uma preocupação crescente da população em relação à presença de radionuclídeos no meio ambiente. As principais atividades que podem contribuir para o incremento da concentração desses contaminantes envolvem tanto processos industriais como aplicações médicas. Não menos importantes, no entanto, são os radionuclídeos naturais encontrados no ambiente, os quais podem ter suas concentrações aumentadas como resultado de beneficiamento de matéria prima para a extração de metais, como é o caso das areias minerais, ricas em cianita, ilmenita rutilo e zirconita, as quais podem apresentar elevadas concentrações de urânio e tório. A quantificação de radionuclídeos envolve, de maneira geral, técnicas de Instrumentação Nuclear. Dentre essas, as espectrometrias alfa e gama estão entre as mais utilizadas nas medições de radionuclídeos naturais em matrizes ambientais. Portanto, tornam-se cada vez mais importantes o estudo e o aperfeiçoamento das metodologias utilizadas em cada uma dessas técnicas, proporcionando maior precisão e exatidão nas determinações. Nesse contexto, o presente trabalho visou a comparação entre as diversas metodologias utilizadas nas técnicas de espectrometria alfa e espectrometria gama para a determinação de 238U e 232Th em amostras ambientais, especificamente em areias minerais. A validação das metodologias utilizadas foi feita utilizando-se materiais de referência fornecidos pela Agência Internacional de Energia Atômica. Para a técnica de Espectrometria Alfa as amostras foram previamente digeridas por fusão alcalina e receberam traçadores de 232U e 229Th. Após a purificação em resina de troca iônica e eletrodeposição em disco de aço inoxidável, as amostras foram contadas por um período de 80.000 segundos em um espectrômetro alfa.Para a espectrometria gama, alíquotas de 50 g de cada amostra foram acondicionadas em potes cilíndricos de plástico e contadas. As aquisições de dados foram feitas por um período de 80.000 segundos e as linhas gama utilizadas para a determinação do 238U foram as de 63 keV, 93 keV e 1001 keV. Para o 232Th, por outro lado, foram utilizadas as linhas de 338 keV, 911 keV e 969 keV. As quatro metodologias de determinação de 232Th (338 keV, 911 keV, 969 keV e espectrometria alfa) geraram valores de concentrações próximos daqueles constantes dos certificados em materiais de referência, indicando a viabilidade da utilização de qualquer das metodologias. Dentre as metodologias estudadas para a determinação de 238U, a espectrometria alfa e a espectrometria gama, pela linha de 1001 keV, foram as mais indicadas para amostras do tipo das analisadas no presente trabalho, pois apresentaram valores em concordância com os constantes dos certificados dos materiais de referência. Os resultados das análises das areias minerais mostraram concentrações de urânio-238 variando de 60 a 12.256 Bq.kg-1, com um valor médio de 3.634 Bq.kg-1. A concentração de atividade média observada nas amostras de zirconita foi de 6.723 Bq.kg-1, enquanto que a atividade média encontrada para as outras areias minerais associadas foi de 545 Bq.kg-1, ou seja, dentre as areias minerais presentes no depósito analisadas, as que merecem maior atenção, do ponto de vista da proteção radiológica, são as de zirconita. Por outro lado, as determinações de tório-232 mostraram concentrações de atividade variando de 40 a 7.205 Bq.kg-1 e um valor médio de 1.465 Bq.kg-1. Apenas duas amostras tiveram concentrações acima desse valor (ambas eram de areias minerais de zircão), o que reforça a necessidade de maior atenção, do ponto de vista da proteção radiológica, para as amostras de zirconita.
There has been a great concern in recent years related to the presence of radionuclides in the environment. The main activities which may contribute for the increase in the concentration of those contaminants in the environment involve industrial processes, as well as, medical applications. Not less important, however, are the natural radionuclides found in the environment, which can be concentrated as a result of raw material transformation. This is the case of mineral sands processing for the extraction of kyanite, ilmenite, rutile and zircon, which can have higher than normal concentrations of uranium and thorium. For the measurement of radionuclides as contaminants, the main forms of determination involve techniques of Nuclear Instrumentation. For this reason, it is very important to study and improve these techniques in order to obtain reliable results, as far as precision and accuracy are concerned. Thus, the present study aimed to compare the techniques of alpha spectrometry and gamma spectrometry for the determination of 238U and 232Th in environmental samples, specifically in mineral sands. The validation of the methodologies was carried out by using reference materials provided by the International Atomic Energy Agency. For the determination of 238U and 232Th by alpha spectrometry, samples were digested by alkaline fusion, spiked with 229Th and 232U tracers, purified by passing through an ion exchange resin, electrodeposited on stainless steel disks and counted for 80,000s. For the determination by gamma spectrometry, 50 g of each of the samples were placed in plastic cylindrical containers and counted for 80,000s. The main gamma lines used for determining 238U were 63 keV, 93 keV and 1001 keV. For 232Th, on the other hand, the 338 keV, 911 keV and 969 keV gamma lines were used. The four methodologies for the determination of 232Th, namely 338 keV, 911 keV, 969 keV and alpha spectrometry, led to concentration values in agreement with the certified values for the reference materials. Among the methods studied for the determination of 238U, alpha spectrometry and gamma spectrometry using the 1001 keV line, were the most suitable for the type of samples analyzed in this study. The results of the analyses performed for mineral sands showed concentrations of uranium-238 ranging from 60 to 12,256 Bq.kg-1, with an average of 3,634 Bq.kg-1. The average activity concentration observed in samples of zircon was 6, 723 Bq.kg-1, while the average activity found for other mineral sands was of 545 Bq.kg-1, showing that zircon sands deserve greater attention, from the standpoint of radiological protection, among the mineral sands analyzed. Moreover, the determinations of thorium-232 showed activity concentrations ranging from 40 to 7,205 Bq.kg-1 with an average of 1,465 Bq.kg-1. Only two samples showed 232Th concentrations above this value (both were of zircon sands), which reinforces the need for greater attention, from the point of view of radiological protection, for samples of zircon.
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MacDonald, Julian. "Analysis of '1'3'7Cs contamination in soil using in-situ gamma spectrometry." Thesis, Bangor University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297869.

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13

Myers, K. J. "Onshore outcrop gamma ray spectrometry as a tool in sedimentological studies." Thesis, Imperial College London, 1987. http://hdl.handle.net/10044/1/47393.

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14

Lucia, Silvio Rogério de. "Desenvolvimento de um software de espectrometria gama para análise por ativação com nêutrons utilizando o conceito de código livre." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-01122009-095027/.

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O Laboratório de Análise por Ativação com Nêutrons (LAN) do Instituto de Pesquisas Energéticas e Nucleares (IPEN), utiliza esta técnica analítica multielementar, baseada na irradiação de uma amostra por um feixe de nêutrons oriundos de um reator nuclear, que induz a radioatividade; que é medida em um espectrômetro de raios gama, para a obtenção dos espectros de raios gama. Neste trabalho é implementado um software denominado de SAANI (Software Análise por Ativação com Nêutrons Instrumental) para análise de espectros de raios gama, desenvolvido para os usuários do laboratório LAN-IPEN, com a filosofia de software livre, para a substituição do software existente VISPECT/VERSÃO 2, e tem como características principais: tornar a interface mais amigável; facilitar a padronização dos procedimentos realizados pelos pesquisadores, estudantes e técnicos; ser extensível com a utilização da tecnologia de plugins; multiplataforma; código livre. O software foi desenvolvido utilizando a linguagem de programação Python, a biblioteca gráfica Trolltech Qt e algumas de suas extensões científicas. Os resultados preliminares obtidos utilizando o software SAANI foram comparados aos obtidos com o software existente e foram considerados bons. Algumas diferenças encontradas foram verificadas oriundas de erros de precisão na implementação do software. O software SAANI está instalado nos computadores de usuários selecionados para a execução de rotinas de análise para uma maior verificação de sua robustez, precisão e usabilidade.
This study developed a specific software for gamma ray spectra analysis for researchers of the Neutron Activation Laboratory (LAN), which was named SAANI (Instrumental Neutron Activation Analysis Software). The LAN laboratory of the Institute for Research and Nuclear Energy (IPEN-CNEN/SP), uses a multielementar analytical technique, based on irradiation of a sample by a flux of neutrons from a nuclear reactor, which induces radioactivity. The sample is then placed in a gamma-ray spectrometer, to obtain the spectrum. With free software philosophy in mind, this software will replace the existing software VISPECT / VERSION 2. The new software´s main features are: a friendlier interface; easier standardization procedure carried out by LAN staff and researchers; adapted to the use of plug technology; multiplatform and code free. The software was developed using the programming Python language, the library Trolltech Qt graphics and some of their scientific extensions. Preliminary results using the SANNI software were compared to those obtained with the existing software and were considered good. There were some errors in accuracy during the implementation of the software. The SAANI software has been installed in selected computers to be used for routine analysis in order to verify its strength, accuracy and usability.
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15

TAKEDA, MAURO N. "Determinacao da correcao para o efeito de soma em cascata para espectrometros de HPGe pelo metodo de Monte Carlo." reponame:Repositório Institucional do IPEN, 2001. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10916.

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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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16

Pracilio, Gabriella. "The utilisation of gamma ray spectrometry, a soil mapping technology, to improve dryland crop production /." Connect to this title, 2007. http://theses.library.uwa.edu.au/adt-WU2007.0099.

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17

Paradis, Hugues. "Développement de la mesure par spectrométrie gamma en coïncidence." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLS215/document.

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Dans le cadre de la mission de surveillance radiologique de l’environnement de l’Institut de Radioprotection et de Sûreté Nucléaire (IRSN), le Laboratoire de Mesure de la Radioactivité dans l’Environnement (LMRE) réalise la mesure de la concentration en activité dans différentes matrices environnementales. Il s’agit de matrices biologiques (mousses aquatiques, algues, lait, légumes …), de sols, d’eaux ou encore de filtres de prélèvement d’aérosols.Les radionucléides artificiels recherchés sont en très faible proportion par rapport à certains radionucléides naturels : le potassium 40 dans les matrices biologiques ou encore les descendants particulaires du radon dans les filtres d’aérosols. L’important fond Compton induit par ces radionucléides naturels dans le spectre gamma complique la détermination des radionucléides présents au niveau trace.Un moyen de s’affranchir de ce fond Compton est de faire une mesure par spectrométrie $gamma$ en coïncidence en utilisant au moins deux détecteurs. La méthode a été développée sur un système existant, le système anti-Compton constitué d’un détecteur germanium entouré d’un scintillateur NaI(Tl), avec le développement d’un algorithme d’analyse et de l’étalonnage par simulation Monte Carlo si nécessaire. De plus, un nouveau système de mesure en coïncidence a été conçu par simulation Monte Carlo puis mis en service pour pallier les limites du système anti-Compton. Ce nouveau système de mesure, nommé Léda, est composé de deux détecteurs germanium face à face, entourés d’un scintillateur NaI(Tl) ; il possède plusieurs voies de mesure, chacune présentant une amélioration en termes de limite de détection pour tous les radionucléides mesurés
The French Institute of Radiation Protection and Nuclear Safety (IRSN) is in charge of the radiological surveillance of the environment. In this framework the Laboratory of Environment Radioactivity Measurement (LMRE) measures the radioactivity concentrations in various environmental samples: biological matrices (aquatic moss, seaweed, milk, vegetables …), soils, waters or aerosol filters.Artificial radionuclides searched are in low proportion compared to natural radionuclides: potassium 40 in biological matrices or radon particular daughters in aerosol filters. The significant Compton continuum induced in the gamma spectrum makes difficult the identification and the quantification of radionuclides present at trace level.The use of two detectors enables to make coincident spectrometry in order to decrease this Compton background. This technique was developed with an existing system of the laboratory, the anti-Compton system, composed of a germanium detector surrounded by a NaI(Tl) scintillator. A data analysis algorithm was developed and also a Monte Carlo calibration if radionuclides measured are not available in standard source. Moreover a new coincident measurement system was designed by Monte Carlo simulation, called Leda consisting of two germanium detectors face to face surrounded by a NaI(Tl) scintillator. This new system overcomes the limits of the anti-Compton system. Different measurement channels improve the detection limits for all radionuclides measured in our laboratory
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18

Bessa, Julian L. "High-resolution outcrop gamma-ray spectrometry of the Lower Lias, Southern Britain." Thesis, University of Oxford, 1995. http://ora.ox.ac.uk/objects/uuid:901bed7b-e4e5-4791-8cf1-496430f7f9b1.

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A detailed stratigraphic analysis of the Lower Lias of southern Britain using the technique of gamma-ray spectrometry is presented. Gamma-ray data were collected, at the maximum stratigraphic resolution possible, from the Rhaetian to Pliensbachian successions exposed in southern Britain in the Bristol Channel Basin, Wessex Basin and East Midland Shelf. The data, in the form of measured gamma-ray signatures and hence geochemical profiles, is placed within a biostratigraphic framework. The outcrop gamma-ray logs collected from the Somerset coast (Rhaetian - Lower Sinemurian) can be subdivided, on the basis of both total gamma-ray signature and elemental log-signature into 9 gamma-ray units. These units are at a higher level of resolution than the single LL 1 gamma-ray unit defined by Whittaker et al (1985) for the Blue Lias in the subsurface. Outcrop gamma-ray correlation is possible between Somerset and Glamorgan, in some cases at a resolution greater than that offered by ammonite subzonal biostratigraphy. This resolution of correlation suggests the presence of a stratigraphic gap in Somerset within the johnstoni Subzone of the planorbis Zone. The outcrop gamma-ray logs collected from the Dorset coast (Rhaetian - Pliensbachian) can be divided into 10 gamma-ray units. These gamma-ray units can be correlated with the subsurface succession in the Winterborne Kingston and the Burton Row boreholes. The ability to correlate across numerous fault blocks and between different basins suggests that the controls upon gamma-ray signature were probably regional. A model is presented in which the degree of detrital influence within a fine grained mud and pelagic carbonate depositional system can be qualitatively assessed. Proximal and distal mudrock facies can be identified from the Th concentration log with proximal facies characterised by a Th concentration 10 ppm and above and distal facies characterised by a Th concentration of 8 ppm and below. The Th concentration log can also be used to determine intervals of mudrock progradation (increasing Th concentration) and retrogradation (decreasing Th concentration). These signatures can be interpreted within a sequence stratigraphic framework, of which the genetic stratigraphic model of Galloway (1989) is most applicable to the Lower Lias of southern Britain. The succession can be divided into eight genetic stratigraphic sequences. Maximum flooding surfaces are inferred at condensed limestone horizons of low Th concentration. The distal expression of the sequence boundary (the correlative conformity) is inferred at horizons of highest Th concentration. The development of anoxia within the epeiric sea can only partly be explained in terms of sequence stratigraphy with anoxia developing during periods of relative sea-level fall and rise or not at all.
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19

DOMIENIKAN, CLAUDIO. "interface eletronica para aquisicao de 12 espectros de coincidencias gama-gama atrasadas." reponame:Repositório Institucional do IPEN, 2001. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10889.

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IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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20

Allyson, Julian David. "Environmental gamma-ray spectrometry : simulation of absolute calibration of in-situ and airborne spectrometers for natural and anthropogenic sources." Thesis, University of Glasgow, 1994. http://theses.gla.ac.uk/2028/.

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The purpose of this work is to investigate experimentally and theoretically a range of problems encountered in calibration of -ray spectrometers (converting count rates to radioelement ground concentrations), for the natural and manmade radionuclides. For in-situ and aerial survey measurements, the form of radionuclide deposition with soil depth, aerial survey altitude, and detector spectral responses are important considerations when calibrating detector systems. A modification of spectral shape is apparent, owing to scattering and attenuation in the soil and air path between source and detector. A variety of depth profiles and detector configurations have therefore been considered, which are usually encountered in practice. It has been shown for the first time, that it is possible to reconstruct the full spectral response of a detector to calibrate a spectrometer from absolutely theoretical first principles. In doing so, one can avoid some of the problems inherent in experimental approaches. After overcoming technical and methodological problems, the work has been successful in all of its objectives. Experimental investigations of in-situ and aerial survey detectors serve as useful validation studies for theoretical models of the same detector types. The research therefore began with laboratory based measurements using point sources of radionuclides of interest. The acquisition of doped concrete calibration pads has enabled comparisons to be made with other facilities and spectrometers found world-wide. Small scale experimental simulations of detector responses at different altitudes have been made using the calibration pads and perspex absorbers. This extends and improves upon previous work done elsewhere, and uses more suitable absorber types. For the consideration of full energy responses only, analytical methods can be conveniently applied.
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21

CHEN, JIANWEI. "ON-LINE INTERROGATION OF PEBBLE BED REACTOR FUEL USING PASSIVE GAMMA-RAY SPECTROMETRY." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1096255485.

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22

Almeida, Jamille da Silveira. "Estudo das impurezas radioativas gama emissoras presentes nos radiofármacos produzidos no IPEN-CNEN/SP." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-10082017-113643/.

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Este trabalho tem como objetivo investigar a concentração de impurezas radioativas gama emissoras presentes nas soluções dos radiofármacos produzidos no Instituto de Pesquisas Energéticas e Nucleares - IPEN em São Paulo. Para que este radiofármaco possa ser utilizado adequadamente, sua qualidade deve ser avaliada de acordo com os procedimentos estabelecidos de acordo com os \"Requisitos Gerais para a Competência de Laboratórios de Teste e Calibração\", ISO / IEC 17025: 2005 e pelas \"Boas Práticas de Fabricação\" (BPF), controladas pela ANVISA (Agência Nacional de Vigilância Sanitária), no Brasil. Para determinar a atividade, dos radiofármacos das impurezas gama emissoras, foi utilizado um espectrômetro gama de alta resolução em duas distâncias fonte-detector; uma de 18 cm e outra de 1,7 cm. Para a distância de 18 cm, o espectrômetro HPGe foi calibrado com energias gama entre 81 kev e 1408 kev, medindo ampolas seladas de 60Co, 133Ba, 137Cs e 152Eu, padronizadas no Laboratório de Metrologia Nuclear (LMN) do IPEN. Para impurezas com baixas atividades, utilizou a distância fontedetector de 1,7 cm. A esta distância, o efeito soma em cascata é muito elevado, tornando difícil a medição das ampolas de calibração padrão, com isso, a curva de eficiência do espectrômetro foi obtida por um código de simulação de Monte Carlo, desenvolvido no IPEN. Neste código, todos os detalhes do sistema de detecção são modelados e as curvas de resposta para raios X e raios gama são calculadas pelo código de transporte de radiação MCNPX. Os espectros gama foram analisados pelo programa Alpino, que aplica o método de integração numérica da área sob os fotopicos de absorção total. Para as impurezas gama emissoras não detectadas visualmente, os limites de detecção foram calculados a partir da taxa de contagem de fundo, sob a área do pico de interesse. As soluções radioativas analisadas foram 67Ga,99Mo, 99mTc, 111In, 131I, 153Sm, 177Lu e 201Tl. Os resultados da relação entre a atividade do radionuclídeo em análise e as impurezas identificadas apresentaram acordo com os certificados de análise dos fabricantes, assim como, com as especificações da ANVISA.
This work aims to investigate the concentration of radioactive impurities gamma emitters in the radiopharmaceutical solutions produced at Nuclear and Energy Research Institute -IPEN in São Paulo, So that this radiopharmaceutical may be used properly, its quality should be evaluated in accordance with the procedures established by quality control agencies, such as \"General Requirements for the Competence of Testing and Calibration Laboratories\", ISO/IEC 17025:2005 and the \"Good Laboratory Practice\" (GLP), controlled by ANVISA (National Agency Health Surveillance), in Brazil, requiring a confirmation of the values of impurities related at the certificates supplied by the manufacturers. To determine the activity, a high resolution gamma spectrometer were used in two source-detector distances. One was 18 cm and the other 1.7 cm. For the 18 cm distance, the high pure germanium spectrometer was calibrated in the energy range between 81 keV and 1408 keV by measuring sealed ampoules of 60Co, 133Ba, 137Cs and 152Eu, standardized at the Nuclear Metrology Laboratory (NML) of IPEN. For lower activity of the impurities, the distance source-detector of 1.7 cm was assumed. However, as at this distance, the sum coincidence effect is very high, making the measurement of the standard calibration ampoules difficult, the spectrometer efficiency curve was obtained by a Monte Carlo simulation code, developed at IPEN. In this code, all details of the detection system are modeled and the response curves for x-rays and gamma rays are calculated by the MCNPX radiation transport code. The gamma spectra were analyzed by Alpino code, which applies the method of numeric peak integration of the area under the photopeaks. For gamma emitter impurities, not visually detected, the decision threshold and the detection limits were calculated from the background count rate, under the peak area. The radiopharmaceutical solutions analyzed were 67Ga,99Mo, 99mTc, 111In, 131I, 153Sm, 177Lu and 201Tl. The results of impurities ratio for analyzed solutions are in accordance with the manufacturers´ certificate and with the ANVISA.
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23

Holmes, Jennifer L. "Radioanalytical techniques applied to environmental chemistry : a two case study /." Thesis, Connect to this title online; UW restricted, 1993. http://hdl.handle.net/1773/8527.

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24

Casanovas, Alegre Ramon. "Development and calibration of automatic real-time environmental radioactivity monitors using gamma-ray spectrometry." Doctoral thesis, Universitat Rovira i Virgili, 2014. http://hdl.handle.net/10803/145442.

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This doctoral thesis presents a collection of six scientific papers, which have been published in peer-reviewed scientific journals, in the field of real-time environmental radioactivity detection. After the contributions of this thesis, the automatic real-time environmental radiation surveillance network of Catalonia provides new and better radiological information. This was achieved thanks to the development and calibration of three types of radioactivity monitors using gamma-ray spectrometry, either with NaI(Tl) or LaBr3(Ce) detectors, which permit the real-time identification and quantification of radioactive isotope content in water and in air. In the thesis, details on general calibration methodologies can be found. The mentioned developments as well as their specific calibrations are also discussed. For each monitor, an evaluation of their measurement capabilities is also performed.
Esta tesis doctoral presenta una colección de seis artículos científicos, que han estado publicados en revistas científicas revisadas, en el campo de la detección de radiactividad ambiental en tiempo real. Después de las contribuciones de esta tesis, la red automática de vigilancia radiológica ambiental en tiempo real de Cataluña dispone de nueva y mejor información radiológica. Esto ha sido logrado gracias al desarrollo y calibración de tres tipos de monitores de radiactividad mediante espectrometría gamma, ya sea con detectores de NaI(Tl) o de LaBr3(Ce), que permiten la identificación y cuantificación en tiempo real del contenido isotópico radiactivo en agua y aire. En esta tesis, se pueden encontrar detalles sobre metodologías generales de calibración así como una discusión de los mencionados desarrollos y sus correspondientes calibraciones específicas. Además, se efectúa una evaluación de las capacidades de medida para cada uno de los monitores.
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Duarte, Cynthia Romariz [UNESP]. "Radioelementos naturais na área do Projeto Rio Preto (GO)." Universidade Estadual Paulista (UNESP), 2002. http://hdl.handle.net/11449/103029.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Os radioelementos naturais U, Th e K foram caracterizados na área do Projeto Rio Preto (GO), executado pela extinta Nuclebrás, após a realização de etapa de campo para reconhecimento da área e amostragem de corpos litológicos das formações aflorantes na área. Sua determinação foi efetuada por espectrometria gama que possibilitou a mensuração dos nuclídeos 40K, 214Bi e 208Tl. Para o universo total de amostras (n = 288) também foram efetuadas análises químicas dos óxidos SiO2, TiO2, Al2O3, Fe2O3, MgO, MnO, K2O, Na2O, CaO e P2O5 com o intuito de se proceder a caracterização química das rochas da região. Os valores de concentração de óxidos e de nuclídeos permitiram a confecção de mapas de sua distribuição pela área de estudo. Para amostras selecionadas foram realizadas leituras de espectrometria alfa para a determinação dos isótopos de U presentes. As razões 234U/238U e eU/U, relativas às leituras por espectrometria alfa e gama, respectivamente, foram determinadas para avaliar a situação de equilíbrio radioativo na cadeia natural de decaimento do urânio. Foi utilizada também a autorradiografia para identificar a presença de minerais radioativos em lâminas de xistos e gnaisses da Formação Ticunzal.
The natural radioelements U, Th and K were characterized in the area of the Rio Preto project held by Nuclebrás, after recognizing the area and sampling the rocks occurring there. The determination was performed by gamma spectrometry that allowed to quantify the nuclides 40K, 214Bi and 208Tl. All rock samples (n = 288) were chemically analyzed in terms of the oxides SiO2, TiO2, Al2O3, Fe2O3, MgO, MnO, K2O, Na2O, CaO and P2O5. The values of concentration of oxides and nuclides were used to generate distribution maps in the studied area. Alpha spectrometry was utilized for selected samples in order to determine the U-isotopes. The 234U/238U and eU/U ratios relative to the alpha and gamma spectrometry readings, respectively, were determined to evaluate the radioactive equilibrium condition in the natural uranium series decay. Autorradiography was also used to identify the presence of radioactive minerals in shales and gneisses from Ticunzal Formation.
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26

Justina, Fabiano Della. "Estudo das variações diurnas de radiação gama atmosférica e sua interferência em levantamentos de espectrometria gama aerotransportada." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/14/14132/tde-18122012-154942/.

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As concentrações de urânio equivalente, tório equivalente, potássio e taxa de exposição foram determinadas em diferentes dias e horários para um mesmo local, a partir de dados gamaespectrométricos aerotransportados, medidos a uma altura média de 81 metros. Os perfis individuais foram então comparados com os perfis médios de todas as medidas. Os efeitos do radônio atmosférico e dos seus produtos de decaimento foram corrigidos com um pacote de cristais detectores extras voltados para cima, e os valores de calibração desses foram determinados a partir dos dados dos testes de radiação gama atmosférica: medidas acima de 760 metros de altura. A influência da radioatividade dos solos e rochas nos detectores voltados para cima foi corrigida de acordo com a técnica desenvolvida por Grasty e Hovgaard (1996) e discutida para as duas situações que elas são propostas.
The concentration of equivalent uranium, equivalent thorium, potassium and exposure rate were calculated on different days and hours for the same location, from airborne gamma ray spectrometric data, measured at an average height of 81 meters. The individual profiles were compared with mean profiles of all the measurements. The effects of atmospheric radon and its decay products were corrected using a pack of additional detectors crystals facing up (upward looking detector), and the calibration values these were determined from test data of atmospheric gamma radiation: measurements above 760 meters in height. The influence of radioactivity in soil and rocks in the upward looking detector was corrected according to the technique developed by Grasty and Hovgaard (1996) and discussed the two situations for which they are proposed.
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Arine, Bruno Burini Robles. "Melhoramento do índice de detecções na espectrometria gama em amostras ambientais usando inteligência artificial /." Sorocaba, 2017. http://hdl.handle.net/11449/148825.

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Orientador: Antonio Cesar Germano Martins
Resumo: A utilização de elementos radioativos se estende hoje a diversos ramos da ciência e tecnologia, exigindo maneiras eficientes, precisas e sustentáveis de monitoramento para a preservação ambiental e a saúde humana. Uma técnica eficiente e não-destrutiva de análise de elementos emissores de raios gama é a espectrometria gama. No entanto, os softwares atuais de análise se deparam com certos empecilhos quando tratam de amostras ambientais, cujas concentrações de radioatividade são próximas do limite de detecção, ou quando certos radionuclídeos de interesse estão sujeitos a interferências. Este trabalho desenvolveu algoritmos de análise através de ferramentas do campo da inteligência artificial, de forma a obter um desempenho superior do que os métodos empregados em softwares clássicos de análise radiométrica. Três classificadores do campo da inteligência artificial foram testados; árvores de decisão (AD), máquinas de vetores de suporte (MVS) e redes neurais artificiais (RNA). Em testes com uma fonte de chumbo-210 de baixa atividade, a MVS obteve acurácia de 0,93, enquanto os métodos tradicionais obtiveram acurácia máxima de 0,73. Em testes com amostras reais de nitrato de uranila, a acurácia de classificação da RNA foi de 0,91, enquanto a acurácia dos métodos tradicionais foi de 0,70. Observou-se que os modelos baseados em inteligência artificial tiveram desempenho superior aos métodos tradicionais em todos os experimentos. Entretanto, esta vantagem diminui à medida que a relaçã... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Usage of radioactive elements is present in several areas of science and technology, requiring efficient, accurate, and sustainable ways of environmental conservation and human health monitoring. Gamma-ray spectrometry is an efficient and non-destructive analysis technique for identification of gamma-ray emitting elements. Nonetheless, current analysis softwares have certain limitations regarding environmental samples, whose radioactivity concentration is often close to the detection limit, or when certain radionuclides of interest are subject to interference. This work aims the development of analysis algorithms based on the field of artificial intelligence in order to achieve better performance than the methods in classical radiometric analysis software. Three artificial intelligence classifiers were tested; decision trees (DT), support vector machines (SVM) and artificial neural networks (ANN). In tests with a low-activity lead-210 source, SVM obtained an accuracy of 0.93, while the traditional methods obtained a maximum accuracy of 0.73. In tests with real samples of uranyl nitrate, the accuracy of ANN classification was 0.91, while the accuracy of the traditional methods was 0.70. It was observed that artificial intelligence-based models performed better than traditional methods in all experiments. However, this advantage decreases as the signal-to-noise ratio of the spectra increases, becoming negligible when the signal-to-noise ratio exceeds the detection limit.
Mestre
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28

Wilhelm, Emilien. "Développement d'algorithmes de détection et d'identification gamma : application à la spectrométrie gamma embarquée." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAE026/document.

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Depuis le début des années 1980, le Commissariat à l’Énergie Atomique développe et met en oeuvre un système de spectrométrie gamma aéroportée, appelé HELINUCTM. Ce système, composé de détecteurs NaI(Tl) d’un volume de 16 L, est utilisé afin d’établir un état des lieux radiologique des sites survolés. Les principales missions du système HELINUC consistent en la réalisation de contrôles environnementaux, l’intervention en situation de crise et la recherche de sources ponctuelles. La réalisation de ces missions nécessite le développement de méthodes d’analyse adaptées. L’approche considérée dans cette thèse repose sur une rupture conceptuelle de l’analyse des spectres par rapport aux méthodes utilisées jusqu’alors au CEA : l’analyse ne repose plus sur une considération individuelle et séquentielle des mesures aéroportées, mais sur une considération globale et simultanée de celles-ci. L’étude et le développement de méthodes statistiques adaptées à la quantification des radionucléides naturels et du 137Cs (de 600 keV à 3 MeV), à l’estimation de la contamination en 241Am (basse énergie, inférieure à100 keV) en cas de crise radiologique et la détection de sources ponctuelles (moyenne énergie, entre 100 keV et600 keV) permettent d’améliorer la précision sur les activités déterminées en vol et la détection de sources de faibles activités
Since the beginning of 1980’s, the CEA has been developing an airborne gamma spectrometry (AGS) system called HELINUCTM using large volume (16 L) NaI(Tl) detectors. HELINUC is used to produce radioactivity mapping of the soil. The different missions of HELINUC are environmental control of radioactivity, nuclear emergency response and research of orphan sources. The continuous development of analysis methods is then required.The approach considered in this thesis is based on a conceptual break from the analysis of spectra compared to the methods used at the CEA until now: the analysis does not rely on an individual and sequential consideration of airborne measurements, but on an overall and simultaneous consideration of them. The study and development of statistical methods for the quantification of natural radionuclides and 137Cs (from 600 keV to 3 MeV), for the estimation of 241Am contamination (low energy, inferior to 100 keV) in case of radiological emergency and for the detection of orphan sources (medium energy, between 100 keV and 600 keV) improve the accuracy of activities estimation and detection of low activities sources
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29

Richardson, Paul Douglas. "Pluton zonation unveiled by gamma ray spectrometry and magnetic susceptibility : the Sheeprock granite, western, Utah /." Diss., CLICK HERE for online access, 2004. http://contentdm.lib.byu.edu/ETD/image/etd614.pdf.

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30

Duarte, Cynthia Romariz. "Radioelementos naturais na área do Projeto Rio Preto (GO) /." Rio Claro : [s.n.], 2002. http://hdl.handle.net/11449/103029.

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Orientador: Daniel Marcos Bonotto
Banca: Marcos Aurélio Farias de Oliveira
Banca: Antenor Zanardo
Banca: Boaventura Freire dos Reis
Banca: Francisco Yukio Hiodo
Resumo: Os radioelementos naturais U, Th e K foram caracterizados na área do Projeto Rio Preto (GO), executado pela extinta Nuclebrás, após a realização de etapa de campo para reconhecimento da área e amostragem de corpos litológicos das formações aflorantes na área. Sua determinação foi efetuada por espectrometria gama que possibilitou a mensuração dos nuclídeos 40K, 214Bi e 208Tl. Para o universo total de amostras (n = 288) também foram efetuadas análises químicas dos óxidos SiO2, TiO2, Al2O3, Fe2O3, MgO, MnO, K2O, Na2O, CaO e P2O5 com o intuito de se proceder a caracterização química das rochas da região. Os valores de concentração de óxidos e de nuclídeos permitiram a confecção de mapas de sua distribuição pela área de estudo. Para amostras selecionadas foram realizadas leituras de espectrometria alfa para a determinação dos isótopos de U presentes. As razões 234U/238U e eU/U, relativas às leituras por espectrometria alfa e gama, respectivamente, foram determinadas para avaliar a situação de equilíbrio radioativo na cadeia natural de decaimento do urânio. Foi utilizada também a autorradiografia para identificar a presença de minerais radioativos em lâminas de xistos e gnaisses da Formação Ticunzal.
Abstract: The natural radioelements U, Th and K were characterized in the area of the Rio Preto project held by Nuclebrás, after recognizing the area and sampling the rocks occurring there. The determination was performed by gamma spectrometry that allowed to quantify the nuclides 40K, 214Bi and 208Tl. All rock samples (n = 288) were chemically analyzed in terms of the oxides SiO2, TiO2, Al2O3, Fe2O3, MgO, MnO, K2O, Na2O, CaO and P2O5. The values of concentration of oxides and nuclides were used to generate distribution maps in the studied area. Alpha spectrometry was utilized for selected samples in order to determine the U-isotopes. The 234U/238U and eU/U ratios relative to the alpha and gamma spectrometry readings, respectively, were determined to evaluate the radioactive equilibrium condition in the natural uranium series decay. Autorradiography was also used to identify the presence of radioactive minerals in shales and gneisses from Ticunzal Formation.
Doutor
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31

CAMARGO, SONIA P. de. "Correlacao angular direcional gama-gama no nucleo de sup76Se." reponame:Repositório Institucional do IPEN, 1998. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10725.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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32

Struwe, Harald. "Spectrometry for the assessment of uranium contamination in buildings." Thesis, Imperial College London, 1998. http://hdl.handle.net/10044/1/8693.

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33

Al-Sulaiti, Huda Abdulrahman. "Determination of natural radioactivity levels in the State of Qatar using high-resolution gamma-ray spectrometry." Thesis, University of Surrey, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.543271.

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34

Magnusson, Åke. "The relationship between airborne gamma-ray spectrometry data and soil moisture in forested areas of Sweden." Thesis, Stockholms universitet, Institutionen för naturgeografi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-137931.

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Measurements and estimations of soil water content are essential information in many differentfields, however, methods for deriving such data are often limited due to scale/spatial resolution, cost and time efficiency, or the presence of a vegetation cover. This thesis examined the relationship between airborne gamma-ray spectrometry (AGRS) data and soil water content in forested areas. In addition, it assessed the feasibility of using AGRS data to predict relative soil moisture for forestry related applications. The study utilized topography-based models, databased on aerial photography, and point soil moisture measurements, which through statistical approaches were assessed for their relationships to the AGRS data in eleven different studyareas located in Sweden. The analyses indicated statistically significant correlations, of weak to moderate strengths, between the AGRS data and the proxy data for soil water content. Also, all analyses indicated that the data from the channels related to potassium-40 decay events (γK) exhibited the strongest relationship to the soil water content proxies. Furthermore, considering the contributing area of an AGRS measurement and also the results obtained in this study, it is suggested that the AGRS data would work better as a predictor of soil moisture regimes on an intermediate to large scale, compared to a smaller scale. At last, although there were limitations to the data used as proxies for soil water content, the analyses suggested that the AGRS data on its own might not be a strong predictor of relative spatial variation in soil moisture. It may however, hold information useful as ancillary data in other methods, as well as hold individualdata points usable for indicating wet areas.
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35

Santos, Luís Gustavo Cofani dos. ""Supressão Compton na análise por ativação neutrônica instrumental de produtos agrícolas destinados à alimentação humana"." Universidade de São Paulo, 2004. http://www.teses.usp.br/teses/disponiveis/64/64132/tde-29052006-112914/.

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A análise por ativação neutrônica instrumental (INAA) é uma opção para o estudo da composição de alimentos, permitindo determinar simultaneamente diversos elementos. Todavia, a deposição incompleta da energia da radiação gama no detector, devido à interação por espalhamento Compton, dificulta as determinações. O acúmulo de contagens na linha de base do espectro torna-se um problema quando existem na amostra radionuclídeos com emissões gama em energias mais altas do que a de interesse. Nesses casos, os supressores Compton podem aumentar a sensibilidade analítica. Aqui, avalia-se o uso de supressão Compton para o estudo de produtos agrícolas destinados à alimentação humana. Todas as medições foram realizadas com um detector de germânio hiperpuro com 55 % de eficiência relativa (1332 keV, 60Co), circundado por detectores de iodeto de sódio (annulus e plug). Espectros com supressão foram adquiridos a partir da detecção em anti-coincidência. Foram também armazenados os espectros sem supressão. Inicialmente, testou-se a capacidade do equipamento em reduzir a região Compton, empregando fontes de 137Cs. Medindo-se na região entre 358 e 382 keV, o melhor fator de supressão foi 5,97, sendo observada variação no valor de acordo com a região Compton escolhida para a medição. Reduções foram notadas no fator de supressão com o aumento da taxa de contagem e da distância fonte-detector. Em verificações realizadas durante 20 semanas, o sistema supressor mostrou-se estável. Para avaliar o uso de supressão Compton na análise de amostras, foram tomados diversos tipos e marcas comerciais de arroz, batata, feijão, ervilha, grão-de-bico e lentilha. Após secagem e moagem, as amostras foram irradiadas em fluxo de nêutrons térmicos de 1x10E13 cm-2 s-1 por 8 horas, no reator IEA-R1m do IPEN/CNEN (Instituto de Pesquisas Energéticas e Nucleares). A radioatividade foi medida em quatro oportunidades, em aproximadamente 3, 7, 15 e 40 dias após a irradiação. A análise foi conduzida pelo método k0, utilizando o programa Quantu. Quinze elementos foram estudados, entretanto Cd e Hg apresentaram-se abaixo dos limites de detecção, o que também occoreu para As, Cr, La e Se em várias amostras. Foram notados alguns comportamentos próprios de cada tipo de produto analisado. Arroz integral, parboilizado e polido, por exemplo, apresentaram diferentes concentrações de K, Rb e Zn. Dentre os elementos com maior potencial tóxico, a presença de um valor médio de 0,3 mg kg-1 de As em arroz foi a única observação. Houve influência de Br, K e Na sobre os limites de detecção para os elementos medidos entre 3 e 8 dias após a irradiação. A razão entre os limites de detecção sem e com supressão mostrou que a determinação de Br, Co, La, Na, Sc e Se não foi favorecida pelo uso do supressor. Para As, Ca, Cd, Cr, Fe, Hg, K, Rb e Zn, observou-se ganho de sensibilidade fortemente dependente da composição do material e das condições experimentais. Os resultados demonstraram que o desempenho do supressor Compton em INAA deve ser individualmente testado para cada tipo de amostra.
Instrumental neutron activation analysis (INAA) is a good option for studying chemical composition of food, allowing the simultaneous determination of several elements. However, the incomplete deposition of gamma-ray energies in the detector crystal due to Compton scatter can elevate the spectrum baseline making difficult the determination of some elements. The problem is particularly important for samples having high activities of radionuclides emitting gamma-rays with energies higher than those to be measured. For such cases, the use of a Compton suppression system can improve the detection limits. Here, the application of a suppression system for the analysis of foodstuff is evaluated. Measurements were carried out with a hyperpure germanium detector with 55 % relative efficiency for the photopeak 1332 keV of 60Co, working in anti-coincidence with two sodium iodine guard detectors (annulus and plug). Suppressed and unsuppressed spectra were simultaneously acquired. Initially, the overall system performance on the reduction of the Compton region was tested using 137Cs. Measuring between 358 and 382 keV, the higher suppression factor was 5.97, being observed a large variation according to the energy region selected for the determination. Reductions were noticed for the suppression factor resulting from increases on counting rate and source-detector distance. The suppression system showed to be stable during twenty weeks of periodic verifications. To evaluate the system performance on real sample analysis, several types and commercial brands of rice, potatoes, beans, peas, chickpeas and lentil were taken. After drying and grinding, samples were irradiated at a thermal neutron flux of 1x10E13 cm-2 s-1 for 8 hours, in the nuclear research reactor IEA-R1m from IPEN/CNEN (Instituto de Pesquisas Energéticas e Nucleares). Each sample was measured after decay periods of about 3, 7, 15 and 40 days. Analysis was conducted by the k0 method using the software package Quantu. Fifteen elements were assessed, however Cd and Hg were below detection limits, as well as As, Cr, La e Se for several samples. The content of some elements were noticed to vary according to the product analyzed or its particular type. Different results, for instance, were obtained for K, Rb and Zn in integral, parboiled and polish rice. Among the elements with potentially high toxicity for humans, the only observation was a mean As content of 0.3 mg kg-1 in rice. There was a significant influence of Br, K and Na on the detection limits for elements measured from 3 to 8 days after the irradiation. The ratio between the detection limits calculated for unsuppressed and suppressed spectra showed that the determination of Br, Co, La, Na, Sc and Se was not improved by using the Compton suppression system. For As, Ca, Cd, Cr, Fe, Hg, K, Rb and Zn, an enhancement in the analytical sensitivity was noted, which was strongly dependent on sample composition and experimental conditions. The results demonstrated that the suppression system performance for INAA should be individually evaluated for each type of matrix to be analyzed.
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36

Barros, Livia Fernandes. "Avaliação da variação da radioatividade natural em areias da praia de Camburi- Vitória- Espírito Santo com fatores climatológicos e geológicos da região." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-18022014-141741/.

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A principal contribuição para a exposição externa aos seres humanos provem da radioatividade natural presente em solos, principalmente do 40K e das séries do 238U e 232Th. No presente trabalho foram determinadas as concentrações de atividade de 226Ra (série do 238U) , 232Th e 40K em amostras superficiais de areia coletadas mensalmente em 11 locais ao longo da Praia de Camburi durante o ano de 2011, selecionados para cobrir toda a extensão da praia. As amostras seladas foram medidas por espectrometria gama, após um tempo de espera de aproximadamente 30 dias, para que fosse atingido o equilíbrio radioativo nas séries do 238U e 232Th. A concentração de atividade do 226Ra foi determinada pela média ponderada das concentrações do 214Pb e do 214Bi, a concentração de atividade do 232Th pela média ponderada das concentrações do 212Pb, do 212Bi e do 228Ac. A atividade do 40K foi determinada pela sua única transição gama de 1460,8 keV. Para todas as amostras, as concentrações foram corrigidas pelos fatores de autoatenuação gama. A partir destas concentrações foram avaliados os índices radiológicos, atividade equivalente em rádio (Raeq), índice de concentração de atividade (Iγ), índice de risco à exposição gama externo (Hext), índice de risco à exposição gama interno (Hint), taxa de dose gama absorvida no ar (D) em nGy.h-1 e dose efetiva anual (E) em mSv.a-1. No local estudado foi realizada uma avaliação da correlação das concentrações de atividade de 226Ra, 232Th e 40K com os fatores geológicos, geográficos, climatológicos (precipitação pluviométrica e temperatura) e oceanográficos (variação da altura das marés). Devido à presença forte de monazita, a concentração de 232Th é mais elevada do que a concentração de 226Ra e 40K. As concentrações de atividade encontradas variaram de 4 Bq.kg-1 a 1380 Bq.kg-1 para o 226Ra, de 9 Bq.kg-1 a 7453 Bq.kg-1 para o 232Th e de 6 Bq.kg-1 a 504 Bq.kg-1 para o 40K. A variação encontrada para o Raeq foi de 20 Bq.kg-1 a 12077 Bq.kg-1 , para o Iγ foi de 0,07 a 42,08, para o Hext foi de 0,05 a 32,61, para o Hint foi de 0,06 a 36,34 e para a taxa de dose absorvida no ar foi de 9 nGy.h-1 a 5160 nGy.h-1. As baixas concentrações de atividade de 226Ra,232Th e 40K em todos os pontos no mês de abril estão possivelmente relacionadas aos valores máximos da variação da altura das marés e da precipitação pluviométrica. A temperatura média de Vitória durante o ano de 2011 não interfere diretamente nas variações observadas nas concentrações de atividade de 226Ra,232Th e 40K das areias. Foi realizada uma avaliação da dose efetiva anual para um indivíduo do público que frequenta a Praia de Camburi durante 8 horas diárias em 1 mês, em janeiro ou em julho, e todas as doses encontradas estão abaixo do limite de 1 mSv.a-1, recomendado pela ICRP 60 para público em geral.
The main contribution to the external exposure to humans comes from gamma emitting radionuclides in soils, especially the 40K and 238U and 232Th series. In this work, the activity concentrations of 226Ra (238U serie), 232Th and 40K in surface sand monthly collected at 11 sites along the Camburi beach during the year 2011, selected to cover the entire length of the beach, were determined. The samples were hermetically sealed and measured by high resolution gamma spectrometry, after a resting time of approximately 30 days, in order to attain the radioactive equilibrium in the 238U and 232Th series. The activity concentration of 226Ra was determined by the weighted average concentrations of 214Pb and 214Bi, the activity concentration of 232Th by the weighted average concentrations of 212Pb, 212Bi and 228Ac. The activity of 40K was determined by its single transition of 1460,8 keV. For all samples the concentrations were corrected by self attenuation factors. From these concentrations, radiological indices like radium equivalent activity (Raeq), activity concentration index (Iγ), external exposure risk index (Hext), internal exposure risk index (Hint), absorbed gamma dose rate in air (D) in nGy.h-1 and annual effective dose (E) in mSv.y-1 were evaluated. In the studied area it was realized an assessment of the correlation of the activity concentrations of 226Ra, 232Th and 40K with the geological, geographical, climatological (rainfall and temperature) and oceanographic (tidal height variation) factors. Due to the strong presence of monazite, the concentration of 232Th is higher than the concentration of 226Ra and 40K. The activity concentrations found ranged from 4 Bq.kg-1 to 1380 Bq.kg-1 for 226Ra, from 9 Bq.kg-1 to 7453 Bq.kg-1 for 232Th and 6 Bq.kg-1 to 504 Bq.kg-1 for 40K. The variation of Raeq from 20 Bq.kg-1 to 12077 Bq.kg-1, of Iγ from 0,07 to 42,08, of Hext from 0,05 to 32,61, of Hint from 0,06 to 36,34 and of absorbed gamma dose rate in air from 9 nGy.h-1 to 5160 nGy.h-1. The low activity concentrations of 226Ra, 232Th and 40K in all points in April , are possibly related to the maxima of the variation of the height of the tides and rainfall. The average temperature of Vitória during the year 2011 does not directly interfere in the observed variations in the activity concentrations of 226Ra, 232Th and 40K sands. The assessment of the annual effective dose to an individual from the public who attends the Camburi Beach throughout 8 hours per day in a month, in January or July, showed that all values are below the limit of 1 mSv.y-1 , recommended by the ICRP 60 for the general public.
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37

Domienikan, Claudio. "Desenvolvimento de um espectrômetro de correlação angular gama-gama perturbada com seis detectores de BaF2 e estudo de interações hiperfinas em composto intermetálico LaMnSi2." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-05122016-144851/.

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Neste trabalho foi desenvolvido um Espectrômetro de Correlação Angular Gama- Gama Perturbada Diferencial em Tempo (CAP) constituído por seis detectores cintiladores de BaF2, para realização de medidas de interações hiperfinas (campo hiperfino magnético e gradiente de campo elétrico) em diversos materiais e propiciar estudos na área da física da matéria condensada. O espectrômetro desenvolvido possui um sistema de aquisição não convencional em comparação aos demais equipamentos destinados a medidas de CAP. Ao invés do tradicional Analisador Multicanal (MCA), este espectrômetro utiliza um sistema de aquisição de dados constituído, basicamente, por um Conversor Analógico Digital (ADC) rápido, uma placa digital (I/O) convencional e um roteador construído no laboratório de Interações Hiperfinas (LIH) do IPEN. Este versátil e eficiente sistema, controlado por um software também criado no LIH em LabVIEW, permite a geração simultânea de 30 espectros de coincidências γ - γ atrasadas, número superior em comparação aos 12 espectros do antigo espectrômetro de quatro detectores. Além de medidas de linearidade, resolução em tempo e tempo morto, o funcionamento e o desempenho do espectrômetro foram comprovados através de medidas de CAP utilizando os núcleos de prova 111In -> 111Cd e 181Hf -> 181Ta, cujos resultados são bem conhecidos da literatura. Foram feitas medidas de interação quadrupolar do 181Ta em háfnio metálico e do 111Cd em cádmio metálico, e de campo hiperfino magnético do 111Cd e do 181Ta em níquel. Os resultados destas medidas se mostraram em concordância com a literatura. Adicionalmente foram realizadas medidas inéditas de interações hiperfinas magnéticas no composto intermetálico LaMnSi2 utilizando os núcleos de prova 111Cd e 140Ce. As medidas foram realizadas na faixa de temperatura de 10 K a 400K. No caso das medidas utilizando a sonda 111In -> 111Cd, os resultados mostram uma variação do campo magnético com a temperatura que segue a função de Brillouin. Já no caso das medidas com o núcleo de prova 140La -> 140Ce, o resultado apresentou um comportamento anômalo do campo hiperfino em função de temperatura. Os resultados evidenciam uma forte hibridização da banda 4f do Ce com a banda 3d do Mn, fato verificado e estudado em trabalhos anteriores com compostos semelhantes.
In this work a Perturbed gama-gama Angular Correlation (PAC) spectrometer was constructed consisting of six BaF2 scintillator detectors to perform measurements of hyperfine interactions (magnetic hyperfine field and electric field gradient) in different materials to study condensed matter physics. The spectrometer developed has an unconventional acquisition system compared to other equipment for PAC measurements. Instead of a traditional multichannel analyzer (MCA), the spectrometer utilizes a data acquisition system consisting of basically a fast analog to digital converter (ADC), a conventional digital card (I/O) and a router constructed in the hyperfine interactions laboratory (LIH) of IPEN. This versatile and efficient system, controlled by software, also developed in the LIH using LabVIEW, allows simultaneous generation of 30 delayed γ - γ coincidence spectra compared to 12 spectra in the old 4 detector spectrometer in our laboratory. In addition to the tests of system linearity, time resolution and dead time, the operational performance of this spectrometer was demonstrated by PAC measurements using 111In -> 111Cd and 181Hf -> 181Ta nuclear probes, for which the results are well known from the literature. The quadrupole interaction of 181Ta in metallic hafnium, and 111Cd in metallic cadmium, and magnetic hyperfine field of 111Cd in nickel, were measured and the results are in agreement with the literature. Additionally the measurements were carried out, with the new spectrometer, to study the hyperfine field in the intermetallic compound LaMnSi2 using 111Cd and 140Ce nuclear probes. The measurements were carried out in the temperature range from 10 K to 400 K. While the temperature dependence of hyperfine field measured with 111In -> 111Cd probe, follows the Brillouin function the behaviour of the hyperfine field measured with 140La -> 140Ce is anomalous. This behavior has been explained in terms of a strong hybridization of 4f band of Ce with the 3d band of Mn, a fact verified in previous studies with similar compounds.
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38

Bajoga, Abubakar D. "Evaluation of natural and anthropogenic radioactivity in environmental samples from Kuwait using high-resolution gamma-ray spectrometry." Thesis, University of Surrey, 2016. http://epubs.surrey.ac.uk/809932/.

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A study of natural radioactivity from ninety different soil samples across the state of Kuwait was carried out with a view to ascertain the level of natural and/or man-made radioactivity from that area. There has been some concern on the levels of NORM following the First Gulf War in which approximately 300 tons of depleted uranium shells were used and in particular, whether it has a significant impact in the surrounding environment. This study uses gamma-spectroscopy in a low background measuring system employing a high resolution Hyper-Pure Germanium detector. The calculated specific activity concentrations are determined for the radionuclides 226Ra, 214Pb, 214Bi and 228Ac, 212Pb, 208Tl following the decays of the primordial radionuclides 238U and 232Th, respectively. The analysis also includes evaluations for the 235U decay chain. In particular, the 186 keV doublet transition is used together with the activity concentration values established from the decays of 214Bi and 214Pb to establish the 226Ra and 235U specific activity concentrations, which can be used to estimate the 235U:238U isotopic ratios and compare to the accepted value for naturally occurring material of 1:138. Specific activity concentration values have also been determined for the 40K and the anthropogenic radionuclide 137Cs (from fallout) were detected within the same samples. Results of the activity concentration gives mean value of 16.99±0.21, 12.79±0.14, 333±37 and 2.18±0.11 Bq/kg for 238U, 232Th, 40K, and 137Cs, respectively. The associated radiological hazard indices from these samples were found to have mean values of 29.13±0.35 nG/hr, 60.20±0.68 Bq/kg, and 35.30±0.40 µSv/year for the dose rates, radium equivalent, and annual dose equivalent, respectively. Analysed results of elemental concentrations of Uranium, Thorium and Potassium were also determined, and were found to range from 0.96±0.02 ppm to 2.53±0.02 ppm, 2.26±0.04 ppm to 5.23±0.05 ppm and a mean value of 1.21±0.03 % for 40K for the northern region, respectively. Overall result indicates values within the world average range. The results obtained for the 235U:238U isotopic ratio gives a mean value of 0.0462, which is consistent with the presence of natural material from the measured location.
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39

Pittauerová, Daniela Verfasser], Helmut [Akademischer Betreuer] [Fischer, and Bernd [Akademischer Betreuer] Zolitschka. "Gamma spectrometry for chronology of recent sediments / Daniela Pittauerová. Gutachter: Helmut Fischer ; Bernd Zolitschka. Betreuer: Helmut Fischer." Bremen : Staats- und Universitätsbibliothek Bremen, 2013. http://d-nb.info/1072078880/34.

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40

Mickum, George Spencer. "Development and testing of an organic scintillator detector for fast neutron spectrometry." Thesis, Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47653.

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The use of organic scintillators is an established method for the measurement of neutron spectra above several hundred keV. Fast neutrons are detected largely by proton recoils in the scintillator resulting from neutron elastic scattering with hydrogen. This leads to a smeared rectangular pulse-height distribution for monoenergetic neutrons. The recoil proton distribution ranges in energy from zero to the incident neutron energy. In addition, the pulse-height distribution is further complicated by structure due to energy deposition from alpha particle recoils from interactions with carbon as well as carbon recoils themselves. In order to reconstruct the incident neutron spectrum, the pulse-height spectrum has to be deconvoluted (unfolded) using the computed or measured response of the scintillator to monoenergetic neutrons. In addition gamma rays, which are always present when neutrons are present, lead to Compton electron recoils in the scintillator. Fortunately, for certain organic scintillators, the electron recoil events can be separated from the heavier particle recoil events in turn to distinguish gamma-ray induced events from neutron-induced events. This is accomplished by using the risetime of the pulse from the organic scintillator seen in the photomultiplier tube as a decay of light. In this work, an organic scintillator detection system was assembled which includes neutron-gamma separation capabilities to store the neutron-induced and gamma-induced recoil spectra separately. An unfolding code was implemented to deconvolute the spectra into neutron and gamma energy spectra. In order to verify the performance of the system, a measurement of two reference neutron fields will be performed with the system, unmoderated Cf-252 and heavy-water moderated Cf-252. After the detection system has been verified, measurements will be made with an AmBe neutron source.
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41

Cavallaro, Francisco de Assis. "As tecnicas NASVD e MNF e sua aplicação na redução de ruidos em dados gamaespectrometricos : Francisco de Assis Cavallaro." [s.n.], 2008. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287723.

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Orientadores: Rodrigo de Souza Portugal, Adalene Moreira Silva
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociencias
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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
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42

Maibane, Kutullo Freedom. "Validation of Gamma Ray spectrometry process used to determine the Radionuclides and radioactivity levels in decorative granite countertops." University of the Western Cape, 2016. http://hdl.handle.net/11394/5876.

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Magister Scientiae - MSc (Physics)
Humans are continuously exposed to low level of ionizing radiation, sources include soil, medical treatment and as well as radiation emissions from natural materials like granite rocks. The radiation levels present in these granite rocks varies depending on the mineral properties and their origins. The aim of this study is to assess the radiation levels in various granite countertops available commercially in South Africa. The radiation levels present in the granite countertop samples were determined using the available low-background HPGe gamma-ray detector system at iThemba LABS. Initially, the study focused on the optimisation of the photopeak efficiencies of the detector system to match the samples, i.e. 'box-like' geometry as opposed to the traditionally used Marinelli beaker geometry. A soil sample with known activity (238U series: 940 30 Bq/kg; 232Th series: 660 20 Bq/kg and 40K: 153 8 Bq/kg) determined with Marinelli beaker geometry was used to prepare an artificial reference material for the new box geometry. The new-efficiency parameters determined were used to calculate the activity concentrations present in the 5 granite countertop samples. The range of activity concentration levels determined in all granite counter samples are 3 +- 610 Bq/kg, 50 +- 170 Bq/kg and 1400 +- 2000 Bq/kg for 238U, 232Th and 40K, respectively. These levels are higher than the world mean values reported by UNSCEAR of 40 Bq/kg, 40 Bq/kg and 370 Bq/kg for 238U (2 samples), 232Th (4 samples) and 40K (all samples), respectively. The estimated absorbed dose rates range from 194(4) to 790(30) nGy/h. The radionuclides 226Ra, 232Th and 40K contributes approximately 44%, 52% and 4%, respectively, of the total absorbed dose rate in all granite countertop samples.
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Clément, Aloïs. "Quantification de radionucléides par approche stochastique globale." Thesis, Université Clermont Auvergne‎ (2017-2020), 2017. http://www.theses.fr/2017CLFAC049/document.

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Parmi les techniques de mesure nucléaire non destructives utilisées par les instrumentistes du noyau atomique, la spectrométrie gamma est aujourd’hui une méthode d’identification et de quantification de radionucléides largement employée dans le cadre de la gestion d’objets nucléaires complexes tels que des déchets radioactifs, des fûts de déchets ou des boîtes à gants. Les caractéristiques physico-nucléaires non-reproductibles et variées de ces objets, telles que leurs compositions, la répartition des matériaux, leurs densités et formes géométriques, ou le nombre et la forme de leurs termes sources émetteurs, induisent une inaptitude des méthodes d’étalonnage traditionnel à permettre l’obtention de l’activité d’un matériau nucléaire donné. Cette thèse propose une méthode de quantification de radionucléides multi-émetteurs, limitant, voire supprimant, l’utilisation d’informations dites a priori issues de l’avis d’expert ou du retour d’expériences. Cette méthode utilise entre autres la métamodélisation pour construire une efficacité de détection gamma équivalente de la scène de mesure, le formalisme de résolution de problème inverse par Chaines de Markov Monte-Carlo (MCMC), le tout placé dans un cadre de travail probabiliste bayésien afin d’estimer les densités de probabilités des variables d’intérêt telle qu’une masse de radionucléide. Un protocole de validation expérimentale permet de vérifier la robustesse de la méthode à estimer une masse de 239Pu au sein d’objets similaires à ceux traités en routine par le laboratoire. Les perspectives de la méthode concernent la réduction des temps de calcul, des coûts financiers et humains par limitation de l’approche type expert, et la réduction des incertitudes associées
Gamma spectrometry is a commonly passive nondestructive assay used to identify and quantify radionuclides present in more or less complex objects such as waste packages, waste drums or glove boxes. Basic methods using empirical calibration with a standard in order to quantify the activity of nuclear materials by determining the absolute calibration efficiency are useless on non-reproducible, complex and single nuclear objects such as waste packages. Package specifications as composition or geometry change from one package to another and involve a high variability of objects. Current quantification process uses numerical modeling of the measured scene with few available data such as geometry or composition. These data are density, material, screen, geometrical shape, matrix composition and source distribution. Some of them are strongly dependent on package data knowledge. The method developed in this thesis suggests combining a global stochastic approach which uses, among others, surrogate models available to simulate the gamma attenuation behaviour, a Bayesian approach which considers conditional probability density functions of problem inputs, and Markov Chains Monte Carlo algorithms (MCMC) which solve inverse problems, with gamma ray emission radionuclide spectrum and outside dimensions of interest objects. The methodology is testing to standard in terms of actinide masses, locations and distributions. Activity uncertainties are taken into account by this adjustment methodology. An experimental protocol is built to validate the quantification method in terms of robustness with the quantification of 239Pu. The perspectives of the method are to save time by improving the nuclear measurement process, to cut back on costs by avoiding as far as possible expert approaches, and to reduce the actinide mass uncertainties by increasing the precision of quantification process
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44

Sergeyeva, Viktoriya. "Développement d'une technique innovante de dosimétrie en réacteur pour la caractérisation du spectre neutronique dans le domaine d'énergie 1 keV - 1 MeV." Thesis, Aix-Marseille, 2016. http://www.theses.fr/2016AIXM4069/document.

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La dosimétrie neutronique en réacteur se base sur l'analyse de l'activité de dosimètres irradiés, dont certains isotopes-cibles sont l'objet de réactions d'activation ou de fission sous l'effet des neutrons. Les différentes cibles sont sensibles aux neutrons d’énergie particulière. La caractérisation des spectres neutroniques est bien établie dans les domaines thermique, epithermique (Eneutron <1 keV) et rapide (Eneutron >1 MeV), mais il y a une absence de détecteur dans le domaine énergétique entre 1 keV et 1 MeV. Le travail de thèse a abouti sur un choix final: la capture (n, γ) sur les isotopes 92Zr et 94Zr, présents dans le zirconium naturel, pour former les isotopes 93Zr (stable) et 95Zr (radioactif). L'expérience ZIMA a été réalisée sur le réacteur OSIRIS pour démontrer la faisabilité de la méthode de détection proposée. Les analyses post-irradiation sont la spectrométrie γ et la spectrométrie de masse par accélérateur. Pour analyser les résultats expérimentaux, ZIMA a été simulée avec le code neutronique TRIPOLI-4 basé sur la méthode de Monte Carlo. Les rapports Calcul/Expérience présentés dans la thèse permettent de conclure que la détection neutronique (1 keV – 1 MeV) par capture de 94Zr et 92Zr donne des résultats probants. Les mesures obtenues sont exploitables
Reactor dosimetry goal is to reconstruct neutron spectrum in a particular reactor location. Today we can reconstruct with precision thermal (MeV) parts of neutron spectrum by using dosimeters with an adequate sensitivity. Nowadays there is no dosimeter for the intermediate energy region 1 keV - 1 MeV. Thus, the PhD goal is to select the 1 keV - 1 MeV sensible target-isotope and nuclear reaction and verify our solution by experimental irradiation. PhD final choice is for neutron capture reaction (n, γ) on 92Zr and 94Zr. Neutron irradiation produces 2 isotopes: 93Zr and 95Zr, stable and radioactive. Irradiation experiment was performed in OSIRIS reactor. Post-irradiation analyses of irradiated Zr samples are γ spectrometry and Accelerator Mass Spectrometry. In order to simulate irradiation experiment we performed calculation with neutron transport code TRIPOLI-4, based on Monte Carlo method. The goal of ZIMA (Zirconium Irradiation for Mass and Activity analysis) experiment was to prove the feasibility of 1 keV - 1 MeV neutron detection by (n,γ) capture on 92Zr and 94Zr under boron nitride filter. C/E ratios presented in this PhD allow us to conclude that activation of 94Zr and 92Zr gives us acceptable results
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45

Uchoa, Juliane Cristina Ferreira. "Analise espacial dos corpos plutonicos do cinturão mineiro atraves da integração de dados geologicos, aerogeofisicos e geoquimicos." [s.n.], 2006. http://repositorio.unicamp.br/jspui/handle/REPOSIP/287404.

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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
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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
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46

Leite, Rafael Valadares. "Desenvolvimento de um espectrômetro nuclear digital de radiação gama." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/3/3139/tde-08032007-175805/.

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O método nuclear gamaespectrométrico vem ganhando espaço em diversas aplicações como fornecer a informação médica em um paciente ou de uma galáxia distante, detectar radioatividade para fins de segurança e medir a concentração de radioelementos em um mineral ou rocha. Esta dissertação apresenta um projeto e implementação de um espectrômetro gama digital conectado a um conjunto detector contendo cristal cintilador de iodeto de sódio dopado com tálio. O hardware é baseado em um dispositivo lógico programável da família CoolRunner II da Xilinx e um conversor analógico-digital de 80 MHz da Analog Devices. A aquisição de dados é executada em um computador pessoal comum. As linguagens de programação utilizadas foram VHDL e C#. O objetivo desta dissertação é apresentar todas as etapas necessárias para o desenvolvimento de um gamaespectrômetro digital e inclui pesquisa bibliográfica, estudo do equipamento, modelagem dos cristais, simulação do projeto de um gamaespectrômetro, montagem do circuito eletrônico, desenvolvimento do processamento e lógica do circuito, criação do software de aquisição dos dados em tempo real e apresentação dos resultados obtidos.
The gammaspectrometric method has been used for diverse applications as to supply the medical information in a patient or a distant galaxy, to detect radioactivity at airport and to measure the concentration of radioelements in a mineral or rock. This work presents a digital gammaspectrometer project and implementation for acquisition of radiometric data, the spectrometer is connected to a gamma-ray detector NaI(Tl). The two main components in hardware are complex programmable logical device of the family CoolRunner II Xilinx and an 80 MHz analog to digital converter of brand Analog Devices. The acquisition of data is executed in a common personal computer. The programming languages used are VHDL and C#. The objective of this work is to present all the needful stages for the digital gammaspectrometry development that includes theorem, equipment studying, crystal modeling, gammaspectrometry modeling and simulation, electronic circuit assembly, processing and logic circuit development, data acquisition software in real time development and presentation of results.
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47

Villa, Marcelo Barros. "Estudo da função resposta de um detector cintilador de Nal(TI)." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-20052014-113830/.

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O conhecimento preciso do espectro energético de fótons é de extrema importância na radioterapia no que se refere à escolha adequada das doses a que os pacientes são submetidos. Os dados de saída dos detectores de radiação são apenas espectros de altura de pulso (PHD), ao invés de espectros de energia, que correspondem a informações distorcidas sobre a fonte e seus decaimentos devido a diversos erros associados ao processo de cintilação do cristal e à eletrônica. Os resultados medidos foram obtidos com o uso de um detector cintilador de NaI(Tl) e as simulações Monte Carlo foram feitas com o uso do programa EGSnrc. A partir das características do detector obtidas experimentalmente, nossas simulações puderam ser validadas para se aproximarem o mais próximo possível do caso real em laboratório. Dessas medidas experimentais de fontes radioativas de calibração e simulações, foi montada uma matriz resposta inversa que transforma PHD em espectro de energia de fótons. Uma vez que a faixa energética das fontes radioativas medidas teve um limite de 1.6MeV, a matriz resposta também o apresenta, mas que pode ser contornado de acordo com a geometria usada para a obtenção do PHD a ser corrigido. Observa-se que a resposta do detector é diretamente proporcional à energia e assim, dependendo da energia incidente a ser estudada, dois tipos de matriz resposta inversa podem ser aplicadas. Os resultados desta transformação de PHD para espectro de energia de fótons são apresentados.
The accurate knowledge of the photon energy spectrum in radiotherapy is of extremely importance when it comes to the appropriate choice for doses whose patients are submitted. The output data from the radiation detectors is described as pulse high distributions, instead of energy spectra, that correspond to distorted information about the source and its decays due to many errors associated to the crystal scintillation process and the electronics. The measured results were obtained with a NaI(Tl) scintillation detector and Monte Carlo simulations were performed by the EGSnrc program. From the detector characteristics obtained experimentally, the simulations were validated so they could approximate the more real as possible as in laboratory. Using these simulated and experimental calibration sources, an inverse response matrix was built and transforms pulse high distributions in photons energy spectrum. Once the correction energy limit due to the radiation sources used is approximately 1.6 MeV, so the response matrix has a limit, but it can be overcame by the beam incident angle and the geometry used when the pulse high distributions to be corrected is going to be measured. One can realize that the detector response is directly proportional to the incident energy and, when it is intense as in a LINAC or weak as in a calibration source, different types of matrix can be applied. The results from these transformations are presented.
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48

Brunčiaková, Miriama. "Studium vlivu jaderných elektráren na životní prostředí pomocí radioanalytických metod." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2016. http://www.nusl.cz/ntk/nusl-220366.

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This thesis' objective is to analyse local environmental impact of NPP. For impact determination, it is necessary to monitor the locality for a long period. For biomonitoring method, gamma-spectrometers might be used. It should be calibrated before the measurement. Within the thesis investigation, spectrometer of the faculty was calibrated in the laboratory of ionizing radiation and three samples of Czech nuclear facilities outlet were analysed.
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49

Richardson, Paul D. "Pluton Zonation Unveiled by Gamma-ray Spectrometry and Magnetic Susceptibility; A Case Study of the Sheeprock Granite, Western, Utah." BYU ScholarsArchive, 2004. https://scholarsarchive.byu.edu/etd/209.

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A radiometric survey of the zoned 21 Ma, A-type Sheeprock granite, western Utah, combined with measurements of magnetic susceptibility and field observations were analyzed using a geographic information system. The intrusion spans 25 square km and is roughly eliptical in shape with its long axis trending northwest. Concentration maps (composed of more than 500 survey stations) of eU, eTh, texture, magnetic susceptibility, color, and joint density help to constrain magmatic and post-magmatic processes related to its chemical and physical zonation. Uranium ranges from 3.9 to 26.9 ppm (mean 12.7) and thorium from 1.7 to 125.7 ppm (mean 45.5). Similarities in spatial patterns and near normal distributions of U and Th imply minimal remobilization and secondary equilibrium of U. Relatively high magnetic susceptibility (6 to 12*10^-3 SI units), low eU and eTh, and limited whole rock chemical anayses show the southeastern part of the pluton is more mafic and most likely formed as an early cumulate. Dominant textures are porphyritic with a fine-grained matrix along the northeastern margin, coarsening to a medium-grained matrix along the southwestern margin. This transition from fine to medium-grained matrix textures is believed to be a preserved solidification front that had migrated from the roof and walls inward during cooling. Late stage magma mixing is evidenced by a string of mafic enclaves along the axis of the pluton near this solidification front. eU and eTh generally increase toward the finer-grained northeastern margin of the pluton. This has been interpreted to be the primary result of fractionation of U and Th into monazite and thorite. As mafic cumulates formed along the northeastern margin residual liquids were displaced inward. This depleted the more evolved parts of the pluton in U and Th. Beryl, a distinquishing characteristic of the most evolved portions of the pluton, is concentrated in two areas along the central axis of the intrusion. The intrusion is a cumulative of three magmatic phases, the second of which crystallized from the margins inward. Joint spacing is a major factor in controlling post-magmatic processes. The pluton has a higher density of joints (10 cm apart) near the upper margins, and fewer joints (> 1 meter apart) at lower elevations. Differential cooling and magma pressures are believed to have controlled the varying joint densities. Increased alteration, oxidation, and red-staining are more prevalent in areas of higher joint density. Magnetic susceptibility is bimodal. The high mode (5.4*10^-3 SI) is on the low end of magnetite-series granites and occurs most often in the white granite. The low mode (0.07*10^-3 SI) implies significant post-magmatic oxidation and the destruction of magnetite and correlates to the red granite. Truncated chemical and textural patterns along the pluton's northwestern margin support evidence for range front normal faulting.
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50

Bordas, Mariano. "Possibilites offertes par l'utilisation simultanee des methodes pixe (particle induces x-ray emission) et pige (particle induced gamma-ray emission) en analyse elementaire." Université Louis Pasteur (Strasbourg) (1971-2008), 1988. http://www.theses.fr/1988STR13009.

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