Dissertations / Theses: 'Gamma-ray spectrometry'

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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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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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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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XHIXHA, Gerti. "Advanced gamma-ray spectrometry for environmental radioactivity monitoring." Doctoral thesis, Università degli studi di Ferrara, 2012. http://hdl.handle.net/11392/2388782.

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The environmental radioactivity monitoring programs start in the late 1950s of the 20th century following the global fallout from testing of nuclear weapons in the atmosphere, becoming a cause of concern regarding health effects. Later, the necessity of world industrialization for new energy sources led to develop national plans on electricity production from nuclear technology, initializing in this context world wide exploration for fuel minerals: uranium exploration gained a particular attention in late 1940's in USA, Canada and former USSR and in 1951 in Australia with respective national plans. Nowadays there are about 440 nuclear power plants for electricity generation with about 70 more NPP under construction giving rise to the nuclear emergency preparedness of a large number of states (like Radioactivity Environmental Monitoring (REM) data bank and EUropean Radiological Data Exchange Platform (EURDEP). Furthermore, a lot of applications in the field of geosciences are related to the environmental radioactivity measurements going from geological mapping, mineral exploration, geochemical database construction to heat -flow studies. Gamma-ray spectroscopy technique is widely used when dealing with environmental radioactivity monitoring programs. The purpose of this work is to investigate the potentialities that such a technique offers in monitoring radioactivity concentration through three different interventions in laboratory, in-situ and airborne measurements. An advanced handling of gamma-ray spectrometry method is realized by improving the performances of instruments and realizing and testing dedicated equipments able to deal with practical problems of radioactivity monitoring. For each of these gamma-ray spectrometry methods are faced also the problems of calibration, designing of monitoring plans and data analyzing and processing. In the first chapter I give a general description for the common radionuclides present in the environment having a particular interest for monitoring programs. Three categories of environmental radionuclides classified according to their origin as cosmogenic, primordial and man-made are discussed. The cosmic rays continuously produce radionulides and also direct radiation, principally high energetic muons. Cosmogenic radionuclides are originated from the interaction of cosmic rays with stable nuclides present in the Earth’s atmosphere. Primordial radionuclides are associated with the phenomenon of nucleosynthesis of the stars and are present in the Earth’s crust. Man-made radionuclides commonly present in natural environments are principally derived from radioactive fallout from atmospheric nuclear weapons testing and peaceful applications of nuclear technology like nuclear power plants for electricity generation and the associated nuclear fuel cycle facilities. A relevant contribution, generally with local implication comes from the so called non-nuclear industries which are responsible for technologically enhancement of natural radioelements producing huge amounts of naturally occurring radioactive materials (NORM/TENORM). In the second chapter is described a homemade approach to the solution of the problem rising in monitoring situations in which a high number of samples is to be measured through gamma-ray spectrometry with HPGe detectors. Indeed, in such cases the costs sustaining the manpower involved in such programs becomes relevant to the laboratory budget and sometimes becomes a limitation of their capacities. Manufacturers like ORTEC® and CANBERRA produce gamma-ray spectrometers supported by special automatic sample changers which can process some tens of samples without any human attendance. However, more improvements can be done to such systems in shielding design and detection efficiency. We developed a fully automated gamma-ray spectrometer system using two coupled HPGe detectors, which is a well known method used to increase the detection efficiency. An alternative approach on shielding design and sample changer automation was realized. The utilization of two coupled HPGe detectors permits to achieve good statistical accuracies in shorter time, which contributes in drastically reducing costs and man power involved. A detailed description of the characterization of absolute full-energy peak efficiency of such instrument is reported here. Finally, the gamma-ray spectrometry system, called MCA_Rad, was used to characterize the natural radioactivity concentration of bed-rocks in Tuscany Region, Italy. More than 800 samples are measured and reported here together with the potential radioactivity concentration map of bed rocks in Tuscany Region. In the third chapter is described the application of portable scintillation gamma -ray spectrometers for in-situ monitoring programs focusing on the problems of calibration and spectrum analysis method. In-situ γ-ray spectrometry with sodium iodide scintillators is a well developed and consolidated method for radioactive survey. Conventionally, a series of self-constructed calibration pads prevalently enriched with one of the radioelements is used to calibrate this portable instrument. This method was further developed by introducing the stripping (or window analysis) described in International Atomic Energy Agency (IAEA) guidelines as a standard methods for natural radioelement exploration and mapping. We realized a portable instrument using scintillation gamma-ray spectrometers with sodium iodide detector. An alternative calibration method using instead well-characterized natural sites, which show a prevalent concentration of one of the radioelements, is developed. This procedure supported by further development of the full spectrum analysis (FSA) method implemented in the non-negative least square (NNLS) constrain was applied for the first time in the calibration and in the spectrum analysis. This new approach permits to avoid artifacts and non physical results in the FSA analysis related with the χ2 minimization process. It also reduces the statistical uncertainty, by minimizing time and costs, and allows to easily analyze more radioisotopes other than the natural ones. Indeed, as an example of the potentialities of such a method 137Cs isotopes has been implemented in the analysis. Finally, this method has been tested by acquiring gamma Ombrone -ray spectra using a 10.16 cm×10.16 cm sodium iodide detector in 80 different sites in the basin, in Tuscany. The results from the FSA method with NNLS constrain have been compared with the laboratory measurements by using HPGe detectors on soil samples collected. In the forth chapter is discussed the self-construction of an airborne gamma-ray spectrometer, AGRS_16.0L. Airborne gamma-ray spectrometry (AGRS) method is widely considered as an important tool for mapping environmental radioactivity both for geosciences studies and for purposes of radiological emergency response in potentially contaminated sites. Indeed, they have been used in several countries since the second half of the twentieth century, like USA and Canada, Australia, Russia, Checz Republic, and Switzerland. We applied the calibration method described in the previous chapter using well -characterized natural sites and implemented for the first time in radiometric data analysis FSA analysis method with NNLS constrain. This method permits to decrease the statistical uncertainty and consequently reduce the minimum acquisition time (which depend also on AGRS system and on the flight parameters), by increasing in this way the spatial resolution. Finally, the AGRS_16.0L was used for radioelement mapping survey over Elba Island. It is well known that the natural radioactivity is strictly connected to the geological structure of the bedrocks and this information has been taken into account for the analysis and maps construction. A multivariate analysis approach was considered in the geostatistical interpolation of radiometric data, by putting them in relation with the geology though the Collocated Cokriging (CCoK) interpolator. Finally, the potential radioelement maps of potassium, uranium and thorium are constructed for Elba Island.

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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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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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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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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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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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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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SHYTI, Manjola. "Calibration and performances of in-situ gamma ray spectrometer." Doctoral thesis, Università degli studi di Ferrara, 2013. http://hdl.handle.net/11392/2388864.

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Since 1896, when Henri Becquerel discovered that penetrating radiation was given off in the radioactive decay of uranium, the studies on radioactivity have been an interest of scientific world. With the spread of nuclear technologies applied to energy, health and industrial production, the theme of environmental radioactivity monitoring increasingly is becoming important to the policies of the health public protection both national and European level. Italy is required to comply with the recommendation of the European Commission of 8 June 2000 on the application of Article 36 of the Euratom Treaty concerning the monitoring of levels of radioactivity in the environment for the purpose of assessing the exposure of the population as a whole. In addition, the World Health Organization has identified the first group of carcinogens gas 222Rn, which is considered the second leading cause, after smoking, of lung tumors. In our environment there are various sources of radioactivity that can be natural or artificial origin. Gamma-ray spectrometry is a widely used and powerful method that can be employed both to identify and quantify radionuclides. The purpose of this work is calibration and performances of in situ a portable gamma ray spectrometer. In the first chapter I have given the necessary concepts for understanding the phenomenon of radioactivity. Qualitatively has been described the process of radioactive decay and its three types which can occur in nature. Three categories of environmental radionuclides, cosmogenic, primordial and man-made are discussed. We are exposed to environmental radiation from different sources. The origin of radioactivity in the environment can be divided into two main sources: (a) natural and (b) man-made sources. Mostly the naturally occurring radiation arises from terrestrial radioactive nuclides that are widely distributed in the earth’s crust and extra-terrestrial sources arising from cosmic ray. Also from human activities arise some other sources concerned with the use of radiation and radioactive materials from which releases of radionuclides into the environment may occur. In the second chapter is described the gamma radiation interacts with matter via three main processes: the photoelectric effect, Compton scattering and pair production The operation of a detector is based on the interaction of photons constituting the incident radiation with the material that constitutes the detector itself.. Thanks to these processes, all or part of the energy possessed by the radiation is transferred to the mass of the detector and then converted into an electrical signal. The basic notions related to the interaction of electromagnetic radiation with matter that we will provide in this chapter will therefore be useful to understand the mechanisms that are at the basis of the generation of a gamma spectrum. In addition, this chapter will briefly describe the two main types of gamma radiation detectors, i.e. the semiconductor detector and the scintillation, in particular the high-pure germanium detector (HPGe) and a sodium iodide detector activated by thallium NaI(Tl). In the third chapter is described the study area in which are performed the measurements of natural radioactivity. The area under consideration is the Ombrone basin located in southern Tuscany and Commune of Schio located in Region of Veneto. During the campaign were acquired in situ 338 spectra, including 80 with the ZaNaI_1.0L placed on the ground (Ombrone), 80 with the ZaNaI_1.0L placed on a tripod at 1m height (Ombrone), 89 with the ZaNaI_1.0L placed on the ground (Schio) and 89 spectra are acquired with a backpack placed on the shoulders of an operator (Schio). In each of the 80 sites which have been realized the measurements of radioactivity with the ZaNaI_1.0L instrument, also have been taken 5 different soil samples, for a total of 400 samples. The abundances of 40K, 238U and 232Th were obtained from the analysis of 338 spectra taken with the ZaNaI_1.0L and 400 spectra measured on soil samples in the laboratory with a high-pure germanium detector (MCA_Rad). Also it is described the procedures of ZaNaI_1.0L portable scintillation gamma-ray spectrometers for in-situ measurements. In the fourth chapter is described the procedure for the preparation of soil samples to be analyzed with the MCA_Rad system. The gamma-ray spectrometry system, called MCA_Rad introduces an innovative configuration of a laboratory high-resolution gamma-ray spectrometer featured with a complete automation measurement process, which can conduct measurements on each type of material (solid, liquid or gaseous) in less than 1 hour. The utilization of two coupled HPGe detectors permits to achieve good statistical accuracies in shorter time, which contributes in drastically reducing costs and man power involved. It is made a description of the characterization of absolute full-energy peak efficiency of such instrument reported here. In the fifth chapter are discussed the correlations between the abundances of 40K, 238U and 232Th measured with the ZaNaI_1.0L and those obtained from laboratory analysis on soil samples. The analysis was focused in particular on the study of four different types of correlation: correlation between in-situ acquisition on ground and laboratory measurements, correlation between in-situ acquisition on tripod and laboratory measurements, correlation between in-situ acquisition on ground and on tripod and correlation between in-situ acquisition on ground and on operator shoulder and the influence of vegetative cover during measurements in-situ.

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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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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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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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Malfrait, Paul. "Temporal spectral unmixing for rapid detection of radiological events by gamma ray spectrometry." Electronic Thesis or Diss., université Paris-Saclay, 2023. http://www.theses.fr/2023UPASG055.

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Cette thèse vise à améliorer les algorithmes de démélange de spectres gamma afin de pouvoir accélérer la détection d'anomalie et l'estimation des contributions des radionucléides contenus dans les filtres aérosols analysés par l'Institut de Radioprotection et de Sûreté Nucléaire. Pour ce faire nous avons développé un algorithme de démélange de spectre qui analyse conjointement plusieurs mesures successives d'un même échantillon.Cet algorithme a ensuite été amélioré afin de pouvoir mener l'analyse en temps réel pendant que la mesure du spectre gamma est réalisée. Divers outils ont dû être développés en même temps que cet algorithme pour permettre d'estimer précisémment les activités des radionnucléides, notamment la calibration des signatures spectrales utilisées lors du démélange.Les résultats de ces études sont présentés dans la thèse à la fois sur des spectres simulés et sur des spectres réels issus des analyses de routine du laboratoire. La détection d'une contamination de ¹²³I à 2 Bq dans un échantillon au bout de 2 minutesde mesure illustre bien l'accélération permise par les développement de cette thèse. En effet, cette détection n'aurait pas été possible avec les outils utilisés en routine The aim of this thesis is to improve spectral unmixing algorithms in gamma ray spectrometry in order to speed up anomaly detection and the estimation of radionuclide contributions in aerosol filter samples analyzed by the French Institute of Radiation Protection and Nuclear Safety. To this end, we have developed an unmixing algorithm that performs joint analysis of several successive measurements of the same sample. This algorithm has been improved to enable online analysis while the gamma-ray spectrum measurement is measured. Various tools had to be developed at the same time as this algorithm to enable radionuclide activities to be estimated accurately, including calibration of the spectral signatures used during the unmixing process.The results of these studies are presented in the thesis both on simulated spectra and on real spectra from the laboratory's routine analyses. The detection of a contamination of ¹²³I at 2 Bq in a sample after 2 minutes of measurement illustrates the acceleration made possible by the developments made during this thesis. Indeed, this detection would not have been possible with the tools used routinely

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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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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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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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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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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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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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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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Valaparla, Sunil K. "Experimental study of the response of semiconductor detectors for EDXRF analysis." To access this resource online via ProQuest Dissertations and Theses @ UTEP, 2009. http://0-proquest.umi.com.lib.utep.edu/login?COPT=REJTPTU0YmImSU5UPTAmVkVSPTI=&clientId=2515.

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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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Barta, Meredith Brooke. "Nanocomposite glass-ceramic scintillators for radiation spectroscopy." Thesis, Georgia Institute of Technology, 2012. http://hdl.handle.net/1853/45851.

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In recent years, the United States Departments of Homeland Security (DHS) and Customs and Border Protection (CBP) have been charged with the task of scanning every cargo container crossing domestic borders for illicit radioactive material. This is accomplished by using gamma-ray detection systems capable of discriminating between non-threatening radioisotopes, such as Cs-137, which is often used in nuclear medicine, and fissile material, such as U-238, that can be used to make nuclear weapons or "dirty" bombs. Scintillation detector systems, specifically thallium-doped sodium iodide (NaI(Tl)) single crystals, are by far the most popular choice for this purpose because they are inexpensive relative to other types of detectors, but are still able to identify isotopes with reasonable accuracy. However, increased demand for these systems has served as a catalyst for the research and development of new scintillator materials with potential to surpass NaI(Tl). The focus of a majority of recent scintillator materials research has centered on sintered transparent ceramics, phosphor-doped organic matrices, and the development of novel single crystal compositions. Some of the most promising new materials are glass-ceramic nanocomposites. By precipitating a dense array of nano-scale scintillating crystals rather than growing a single monolith, novel compositions such as LaBr₃(Ce) may be fabricated to useful sizes, and their potential to supersede the energy resolution of NaI(Tl) can be fully explored. Also, because glass-ceramic synthesis begins by casting a homogeneous glass melt, a broad range of geometries beyond the ubiquitous cylinder can be fabricated and characterized. Finally, the glass matrix ensures environmental isolation of the hygroscopic scintillating crystals, and so glass-ceramic scintillators show potential to serve as viable detectors in alpha- and neutron-spectroscopy in addition to gamma-rays. However, for the improvements promised by glass-ceramics to become reality, several material properties must be considered. These include the degree of control over precipitated crystallite size, the solubility limit of the glass matrix with respect to the scintillating compounds, the variation in maximum achievable light yield with composition, and the peak wavelength of emitted photons. Studies will focus on three base glass systems, sodium-aluminosilicate (NAS), sodium-borosilicate (NBS), and alumino-borosilicate (ABS), into which a cerium-doped gadolinium bromide (GdBr₃(Ce)) scintillating phase will be incorporated. Scintillator volumes of 50 cubic centimeters or greater will be fabricated to facilitate comparison with NaI(Tl) crystals currently available.

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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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Burns, Kimberly Ann. "Coupled multi-group neutron photon transport for the simulation of high-resolution gamma-ray spectroscopy applications." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/29737.

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Thesis (Ph.D)--Mechanical Engineering, Georgia Institute of Technology, 2010. Committee Chair: Hertel, Nolan; Committee Member: Kulp, William David; Committee Member: Lee, Eva; Committee Member: Pagh, Richard; Committee Member: Petrovic, Bojan; Committee Member: Rahnema, Farzad; Committee Member: Smith, Eric; Committee Member: Wang, Chris. Part of the SMARTech Electronic Thesis and Dissertation Collection.

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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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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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Marks, Alan Stephen. "Remote sensing of the regolith, Shoalwater Bay area, Queensland." Thesis, Canberra, ACT : The Australian National University, 1993. http://hdl.handle.net/1885/140068.

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Titus, Nortin P. "Response of NaI(T1) detectors in geophysical applications." Thesis, Stellenbosch : Stellenbosch University, 2005. http://hdl.handle.net/10019.1/50441.

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Thesis (MSc)--Stellenbosch University, 2005. Some digitised pages may appear illegible due to the condition of the original hard copy. ENGLISH ABSTRACT: Airborne gamma-ray spectrometry is used for exploration and environmental monitoring over large areas. Such datasets of 7-ray are acquired using large 16l NaI(T1) detector crystals mounted in an aircraft. The response of these detectors to naturally occurring radioactive isotopes is a function of detector volume, efficiency and resolution. This response is modelled using the Monte Carlo method. A photon-electron transport computer code, NIPET, is written to calculate the intrinsic efficiency and photofraction of these large prismatic crystals. The intrinsic efficiency indicates the number of incident photons that interact in some way with the detector resulting in a deposition of energy in the crystal. The photofraction, on the other hand, indicates how many of these photons that impinge on the detector are actually recorded with their full initial energy. This study presents explicity calculated photofraction values for 16l NaI(Tl) crystals. Comparison of these new values, calculated with this computer program, with that of published values for small 3" x 3" crystals shows good agreement. However, for large crystals, the calculated values differ from those in the literature by almost 15%. The study also finds that for the gamma-ray energy range between 0.2 - 3.0 MeV, these detectors have an intrinsic efficiency above 90%, whereas the photofraction values range from 80% for low energy photons to above 40% for high energy photons in the case of large crystals. AFRIKAANSE OPSOMMING: Lug gamma-straal spektroskopie is nuttig vir eksplorasie en omgewings ondersoeke oor groot areas. Metings word tipies gedoen met 16l NaI(T1) detektors wat monteer is in ’n vliegtuig. Die respons van hierdie detektors ten opsigte van natuurlike radioaktiewe isotope is ’n funksie van detektorvolume, doeltreffendheid en oplosvermoë. Hierdie respons word gemodeleer deur gebruik te maak van ’n Monte Carlo tegniek. ’n Rekenaarprogram, NIPET, is geskryf om die intrinsieke doeltreffendheid en fotofraksie vir hierdie groot prismatiese kristalle te bereken. Die intrinsieke doeltreffendheid dui die breukdeel van die invallende fotone aan wat ’n interaksie ondergaan binne die detektor kristal en sodoende energie deponeer. Die fotofraksie, daarenteen, dui die breukdeel invallende fotone aan wat absorbeer word deur die kristal met hul voile invallende energie. In hierdie tesis word eksplisiete fotofraksiewaardes vir 16l NaI(T1) kristale bereken. Goeie ooreenstemming word gevind tussen fotofraksie waardes bereken met hierdie program en die waardes gepubliseer in die literatuur vir klein 3" x 3" kristalle. Vir groter kristalle is daar egter swakker ooreenstemming. Berekende fotofraksie waardes verskil met 15% van die waardes in die literatuur. Daar word ook bevind dat vir gamma-energie tussen 0.2 - 3.0 MeV, die intrinsieke doeltreffendheid vir hierdie tipe detektors bo 90% is en dat fotofraksiewaardes wissel tussen 80% vir lae energie tot bo 40% vir hoë foton energie.

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Dursun, Serkan. "Nuclear structure of the N=88 isotones: the decay of 156Tm to 156Er." Diss., Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/37155.

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The N=88 nuclei lie in a transitional region of the nuclear chart. Collective structure and nuclear deformation for this region is commonly occurring. Previously, some of the nuclei having 88 neutrons have been well studied, e.g., 148Nd, 150Sm, 152Gd, 154Dy; however, 156Er has not. To be able to understand the nuclei in this region one needs to extract all the systematics of these deformed nuclei and the relations between them. The structure of 156Er is the main focus in this thesis and the work seeks understanding of the N=88 nuclei and systematics among them. To accomplish this task, 156Tm to 156Er beta decay was studied. Many new levels and gamma transitions have been added to the existing scheme. The significance for detailed decay scheme studies far from stability is also discussed.

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Kastlander, Johan. "In situ measurements of radionuclide concentration in soil : An investigation into detector properties and methods." Doctoral thesis, Stockholms universitet, Fysikum, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-47398.

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In case of a release of radioactive nuclides into the environment it is necessary to have reliable methods to estimate the potential effect on people and the ecosystem. In this context the total activity deposited, the elemental composition and the depth distribution are of importance. An efficient in situ method to estimate the average contamination over larger areas using high purity germanium (HPGe) detectors has been developed. The method combines simulation of photon transport with measured detector properties. The total activity of 137Cs determined from gamma-ray spectra recorded in situ are compared to results from soil sampling. Another in situ method has been developed to determine the depth distribution of a radionuclide contamination, using an array of small detectors inserted into the ground, as an alternative to the standard procedure of soil sampling. The possibility to use cadmium telluride (CdTe) detectors as well as lanthanum bromide (LaBr3) detectors has been investigated. As a demonstration of the developed method the small-scale variation of the activity distributions in an area covering 350 m2 have been measured and is compared to results obtained by other methods. At the time of the doctoral defense, the following paper was unpublished and had a status as follows: Paper 4: Submitted.

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Reinhardt, Nadja [Verfasser], and Ludger [Akademischer Betreuer] Hermann. "Gamma-ray spectrometry as auxiliary information for soil mapping and its application in research for development / Nadja Reinhardt ; Betreuer: Ludger Hermann." Hohenheim : Kommunikations-, Informations- und Medienzentrum der Universität Hohenheim, 2019. http://d-nb.info/1198308192/34.

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Prieto, Butillé Elena. "Adecuación y desarrollo de métodos de análisis de datos obtenidos mediante espectrometría gamma para la medida de la radiactividad ambiental en tiempo real." Doctoral thesis, Universitat Rovira i Virgili, 2017. http://hdl.handle.net/10803/461883.

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La Xarxa de Vigilància Radiològica Ambiental de la Generalitat de Catalunya està constituïda per diversos tipus de detectors per a la mesura automàtica en continu i en temps real de la radiació ambiental. Entre ells destaquen els monitors d’espectrometria gamma amb detectors d’escintil•lació de NaI (Tl) i LaBr3 (Ce). Les mesures ambientals registrades amb monitors d'espectrometria gamma en temps real no tenen significat radiològic fins que se sotmeten a processos d'adequació. Aquests processos comprenen l'estabilització d'espectres, els calibratges del monitor en energia, resolució i eficiència i la sostracció del fons intrínsec del detector. En aquest estudi es presenta el procés d'adequació d'espectres per a un monitor d'aigua amb detector de LaBr3 (Ce). Els espectres gamma estabilitzats i calibrats poden ser sotmesos a processos d'anàlisi de dades. A partir dels espectres es pot obtenir l'equivalent de dosi ambiental H*(10) o la concentració d'activitat dels isòtops escollits. L'equivalent de dosi ambiental H*(10) és la magnitud que s'usa en la legislació relacionada amb el límit de dosis del públic. Es presenta un mètode per al càlcul del H*(10) obtingut a partir d'espectres gamma ambientals basat en mètodes de Montecarlo amb el codi EGS5. Els valors obtinguts de les dades espectromètriques d'un monitor amb detector de LaBr3(Ce) es comparen amb els proporcionats per un comptador Geiger Muller calibrat en H*(10). Finalment, es presenta un mètode d'anàlisi d'espectres gamma per regions espectrals per a la monitorització automàtica i en temps real de la concentració d'activitat d'isòtops naturals i artificials. El mètode soluciona el solapament de pics i elimina la contribució addicional causada per la presència de radiació natural dins de cada regió. Es presenten resultats de mesures de laboratori per isòtops artificials (Cs-137 i I-131) i naturals (Bi-124 i Pb-214). La Red de Vigilancia Radiológica Ambiental de la Generalitat de Catalunya está constituida por varios tipos de detectores para la medida automática en continuo y en tiempo real de la radiación ambiental. Entre ellos destacan los monitores de espectrometría gamma con detectores de centelleo de NaI(Tl) y LaBr3(Ce). Las medidas ambientales registradas con monitores de espectrometría gamma en tiempo real carecen de significado radiológico hasta que se someten a procesos de adecuación. Estos procesos comprenden la estabilización de espectros, las calibraciones del monitor en energía, resolución y eficiencia y la sustracción del fondo intrínseco del detector. En este estudio se presenta el proceso de adecuación de espectros para un monitor de agua con detector de LaBr3(Ce). Los espectros gamma estabilizados y calibrados pueden ser sometidos a procesos de análisis de datos. A partir de los espectros se puede obtener el equivalente de dosis ambiental H*(10) o la concentración de actividad de isótopos escogidos. El equivalente de dosis ambiental H*(10) es la magnitud usada en la legislación relacionada con las dosis del público. Se presenta un método para el cálculo del H*(10) obtenido a partir de espectros gamma ambientales basado en métodos de Montecarlo con el código EGS5. Los valores obtenidos de los datos espectrométricos de un monitor con detector de LaBr3(Ce) se comparan con los proporcionados por un contador Geiger Muller calibrado en H*(10). Por último, se presenta un método de análisis de espectros gamma por regiones espectrales para la monitorización automática y en tiempo real de la concentración de actividad de isótopos naturales y artificiales. El método solventa el solapamiento de picos y elimina la contribución adicional causada por la presencia de radiación natural dentro de cada región. Se presentan resultados de medidas de laboratorio para isótopos artificiales (Cs-137 y I-131) y naturales (Bi-124 y Pb-214). The Environmental Radiological Surveillance Network implemented in Catalonia consists of several types of detectors for real time automatic measurement of the environmental radiation. Among these are the gamma spectrometry monitors using NaI (Tl) and LaBr3 (Ce) scintillation detectors. Environmental measurements measured with real-time gamma-ray spectrometry monitors are not significant until they are adequately processed. These processes include spectrum stabilisation, energy, resolution and efficiency calibrations and subtraction of the detector's intrinsic background. This study presents the process of spectra adequacy for a water monitor with LaBr3(Ce) detector. Stabilised and calibrated spectra can be subjected to data analysis processes. Form spectra, the ambient dose equivalent H*(10) or the activity concentration of isotopes can be obtained. The ambient dose equivalent H*(10) is the quantity used in legislation related to limits on dose to public exposure. We present a method for the calculation of H*(10) obtained from environmental gamma spectra based on Monte Carlo simulations with the EGS5 code. The values obtained from the spectrometric data registered by a monitor with a LaBr3(Ce) detector are compared with those provided by a Geiger Muller counter calibrated in H*(10). Finally, a spectral regions analysis method of gamma spectra is presented for the automatic and real-time monitoring of the activity concentrations of natural and artificial isotopes. The method solves peak overlapping and eliminates the additional contribution caused by the presence of natural radiation within each region. Results of laboratory measurements for artificial (Cs-137 and I-131) and natural (Bi-124 and Pb-214) isotopes are presented.

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Barbosa, Eder Queiroz [UNESP]. "Calibração de detectores cintiladores e sua aplicação em medidas radiométricas." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/151412.

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Submitted by EDER QUEIROZ BARBOSA (ederqb_eaunesp@hotmail.com) on 2017-08-25T17:41:03Z No. of bitstreams: 1 DISSERTACAO MESTRADO BARBOSA, E. Q. FINAL CORRIGIDA.pdf: 9658662 bytes, checksum: 8ed25992d35956a209ef71c55c30f430 (MD5) Approved for entry into archive by Monique Sasaki (sayumi_sasaki@hotmail.com) on 2017-08-25T17:57:43Z (GMT) No. of bitstreams: 1 barbosa_eq_me_rcla.pdf: 9658662 bytes, checksum: 8ed25992d35956a209ef71c55c30f430 (MD5) Made available in DSpace on 2017-08-25T17:57:43Z (GMT). No. of bitstreams: 1 barbosa_eq_me_rcla.pdf: 9658662 bytes, checksum: 8ed25992d35956a209ef71c55c30f430 (MD5) Previous issue date: 2016-10-03 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) O presente trabalho descreve etapas realizadas para a viabilização de novas metodologias de calibração de sistemas radiométricos portáteis utilizados no LABIDRO (Laboratório de Isótopos e Hidroquímica) do DPM (Departamento de Petrologia e Metalogenia) do IGCE (Instituto de Geociências e Ciências Exatas) da UNESP, Campus de Rio Claro. Dentre os tópicos abordados estão a determinação de tempos de detecção de maior precisão, curvas de calibração dosimétrica e a aquisição de dados de dosimetria no ar, para ambientes indoor e outdoor, por intermédio de gamaespectrômetros portáteis. Os modelos geoestatísticos gerados a partir da conversão de dados em dose efetiva para os locais analisados nos departamentos do Curso de Geologia da UNESP de Rio Claro (SP), demonstraram que apesar de existirem alguns valores situados acima daqueles recomendados pela ICRP e norma CNEN-NN-3.01 de 1 mSv.ano-1, não há a necessidade de intervenção nos locais onde ocorreram (Museu Heinz Ebert; Litoteca do DPM) pois, não são de uso frequente e, além disso, situam-se abaixo do limite recomendado de 20 mSv.ano-1 para indivíduos ocupacionalmente expostos. The present work describes steps undertaken for the viability of new radiometric methodologies of the portable systems calibration used in the LABIDRO (Isotopes and Hydrochemistry Laboratory) of DPM (Petrology and Metalogeny Department) of IGCE (Geoscience and Exact Sciences Institute) at UNESP, Rio Claro Campus. Among the topics covered are the determination of detection times with greater accuracy, dosimetric calibration curves and dosimetry data acquisition in the air, for indoor and outdoor environments, through gamma spectrometer detectors. Geostatistical models generated from the conversion of data, to the sites analyzed in the departments of Geology Course at UNESP, in effective dose, have shown that although there are some values set above those recommended by ICRP and by legal norm CNEN-NN-3.01 of 1 mSv.year-1, there is no need to intervene in places where it occurred (Heinz Ebert Museum; Deposit of rocks and minerals - DPM), Since these sites are of short period of visit time and, in addition, are below the recommended limit of 20 mSv.year-1 for occupationally exposed individuals. CAPES: 00.889.834/0001-08

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

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Carlos, Dionisio Uendro. ""Desenvolvimento e construção de blocos de concreto radioativo para a calibração de espectrômetros gama portáteis e aerotransportados, utilizados em exploração mineral e de hidrocarbonetos"." Universidade de São Paulo, 2006. http://www.teses.usp.br/teses/disponiveis/14/14132/tde-31052006-085228/.

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Oito blocos transportáveis para calibração foram construídos para serem utilizados como padrões de concentração na calibração de espectrômetros gama portáteis e aerotransportados. Todo o procedimento de construção é descrito em detalhe. Os blocos, com dimensões de 1 m x 1 m x 0,30 m e massas variando entre 593 kg e 673 kg, devem a sua radioatividade à adição de diferentes quantidades de feldspato potássico (ortoclásio), caldasito e areia monazítica à massa de concreto. As concentrações de potássio, urânio e tório variam significativamente de um bloco para outro atingindo valores máximos de 5,7% de K, 45,6 ppm eU e 137 ppm eTh. A distribuição do fluxo de radiação gama proveniente da superfície dos blocos de concreto e a magnitude das heterogeneidades na concentração dos elementos radioativos foi determinada experimentalmente. Como exemplo de aplicação apresenta-se o resultado da calibração de um espectrômetro gama portátil. Eight transportable calibration pads were built in to be used as concentration standards for portable and airborne gamma spectrometers calibrations. The pads construction procedure is described in full detail. The pads, with dimensions of 1 m x 1 m x 0,30 m and masses between 593 kg and 673 kg were made radioactive by the addition of different amounts of k-feldspar, caldasite and monazitic sand to the concrete masses. The potassium, uranium and thorium concentration vary significantly in the pads, reaching maximum values of 5,7% of K, 45,6 ppm eU and 137 ppm eTh. The distribution of the gamma radiation flux from the pads surfaces and the heterogeneity magnitudes of the radioactive elements concentration were experimentally established. An example of gamma spectrometer calibration is presented.

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Neddermann, Till [Verfasser], Claus [Akademischer Betreuer] Gößling, and Kai [Gutachter] Zuber. "Material screening by means of low-level gamma ray spectrometry with the Dortmund Low Background HPGe Facility / Till Neddermann. Betreuer: Claus Gößling. Gutachter: Kai Zuber." Dortmund : Universitätsbibliothek Dortmund, 2014. http://d-nb.info/1106257510/34.

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

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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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Magalhães, Luciola Alves 1981. "Caracterização espectral de macro e microexsudações de hidrocarbonetos em bacias continentais brasileiras." [s.n.], 2015. http://repositorio.unicamp.br/jspui/handle/REPOSIP/286641.

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

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Král, Dušan. "Studium využití thoria v jaderných reaktorech řízených urychlovačem." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2017. http://www.nusl.cz/ntk/nusl-318864.

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This thesis deals with the idea of using accelerator driven systems for thorium transmutation into the fissile material, which can be utilized in the accelerator driven systems and in thermal nuclear reactors. Thorium occurs on Earth only in fertile isotope Th-232. It can be converted to fissile U-233 by neutron capture and subsequent beta decay. The experimental part handles the data measured by the irradiation of four thorium samples by the secondary neutrons in the QUINTA spallation target, which was irradiated with 660~MeV protons. Reaction rates for the fission and spallation products were estimated using gamma spectroscopy and activation techniques. Furthermore, Pa-233 production rates were also determined in all experimental samples. Pa-233 and fission production rates were calculated in all experimental samples using the MCNPX transport code and evaluated nuclear data for high-energy reactions. The experimental results are of a great importance for the future investigation of thorium in the accelerator driven system concept, validation of Monte-Carlo based calculation codes and validation of high-energy nuclear models.

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Jahnke, Viktor. "Medidas das seções de choque de ionização da camada K de Au e Bi por impacto de elétrons." Universidade de São Paulo, 2012. http://www.teses.usp.br/teses/disponiveis/43/43134/tde-08032013-123636/.

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Mediu-se a seção de choque de ionização da camada K de átomos de Au e Bi por impacto de elétrons com energias entre os respectivos potenciais de ionização (80 e 90 keV) e 100 keV. Filmes finos de Au e Bi, evaporados em suportes de filmes finos de C, foram posicionados numa câmara de vácuo perpendicularmente ao feixe de elétrons do sistema injetor do Mícrotron da Universidade de São Paulo, Brasil. Os raios x emitidos num ângulo de 120 graus em relação à direção do feixe de elétrons foram observados com um detetor de HPGe planar, cuja eficiência total de pico foi determinada com fontes radioativas de atividades conhecidas. Para cada energia de feixe, a seção de choque experimental de produção de raios x foi determinada com base nas áreas dos picos $K\\alpha_{2,1}$ característicos, na área do espectro de bremsstrahlung próxima ao \"tip\" e na seção de choque duplamente diferencial de produção de bremsstrahlung teórica. Valores tabelados de fluorescence yield e taxa de emissão de raios x foram empregados para converter seções de choque de produção de raios x em seções de choque de ionização. Os resultados experimentais obtidos são ligeiramente maiores do que os resultados de cálculos recentes baseados na aproximação de Bohr com ondas distorcidas. No caso do Au, os poucos resultados encontrados na literatura para energias próximas ao limiar de ionização diferem entre si quase por um fator 4 a 100 keV, e a seção de choque obtida neste trabalho se encontra próxima do valor médio desses dados. Por outro lado, este experimento fornece as primeiras medições da seção de choque de ionização da camada K do Bi para energias menores que 2 MeV. The cross sections for the ionization of the K shells of Au and Bi atoms by electrons with energies from 100 keV down to the respective thresholds (80 and 90 keV) were measured. To this end, thin films of Au and Bi, evaporated on very thin C backings, were positioned in a vacuum chamber perpendicularly to the electron beam delivered by the the microtron injector at the Universidade de São Paulo, Brazil. The x-rays emitted at an angle of 120 degrees relative to the beam direction were observed with a planar HPGe detector, whose full-energy peak efficiency curve had been determined using radioactive sources of known activities. For each beam energy, the experimental x-ray production cross section was determined using the area of the characteristic $K\\alpha_{2,1}$ peaks, the area of the spectrum in an energy interval close to the bremsstrahlung tip and the theoretical doubly-differential bremsstrahlung cross section. Tabulated fluorescence yields and x-ray emission rates were employed to convert x-ray production to ionization cross sections. The obtained experimental values for the K shells of the studied atoms are slightly larger than that of recent calculations carried out within the distorted-wave Born approximation. In the case of Au, the few measurements reported in the literature at energies close to the threshold differ by almost a factor of 4 at 100 keV, and our cross sections lie between those older data. On the other hand, the present experiment provides the first cross section measurements for the K shell ionization of Bi below 2 MeV.

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Máduar, Marcelo Francis. "Desenvolvimento de um código computacional aberto de análise quantitativa para determinação de radionuclídeos por espectrometria gama com detectores semicondutores." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/85/85131/tde-12082011-150805/.

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A quantificação da atividade de radionuclídeos emissores de raios gama em amostras medidas por espectrometria gama com detectores HPGe depende da análise dos fotopicos presentes no espectro, especialmente da determinação exata das suas áreas líquidas. Tal análise é geralmente realizada com o auxílio de ferramentas de software proprietário. Este trabalho apresenta uma metodologia, descrição de algoritmos e um aplicativo de código aberto, denominado OpenGamma, para a busca e análise de fotopicos a fim de se obter seus parâmetros relevantes e as atividades dos radionuclídeos na amostra. A implementação computacional é distribuída sob licença aberta para o código principal e com o uso de pacotes de software aberto para o projeto da interface e para bibliotecas matemáticas. O procedimento para a busca de picos é realizado em três etapas. Primeiramente, executa-se uma pesquisa preliminar com o método da segunda diferença, que consiste na geração de um espectro derivado para a busca de picos candidatos. Na segunda etapa, calculam-se as larguras experimentais dos picos, dos quais escolhem-se aqueles bem formados e isolados para a obtenção da função de ajuste da largura vs. canal, por meio do método de Levenberg-Marquardt para ajustes não-lineares. Por fim, regiões do espectro com picos agrupados são delimitadas e novo ajuste não-linear é aplicado a cada região para a obtenção dos termos da linha de base e dos fotopicos. A partir destes termos, são calculadas as áreas líquidas dos picos. Para a determinação da atividade, curvas de calibração de eficiência previamente obtidas, bem como dados de transições gama dos radionuclídeos, são incorporadas ao código e aplicadas. O código foi escrito em linguagem C++ e a interface foi desenvolvida com a ferramenta Qt. Para as funções matemáticas e procedimentos de ajuste, foi usada a biblioteca científica GNU (GSL). A validação de código foi feita por meio da análise de: 1) espectros sintéticos de teste da AIEA, especialmente desenhados para a avaliação de desempenho de software; 2) espectros obtidos com amostras de exercícios de intercomparação e 3) espectros da rotina de trabalho do Laboratório de Radiometria Ambiental (LRA) do IPEN e analisados com o aplicativo comercial InterWinner. Os resultados obtidos são consistentes com os valores de referência e com aqueles obtidos pelo aplicativo citado, sugerindo que o código OpenGamma pode ser utilizado com segurança na espectrometria de raios gama de uso geral. Radioactivity quantification of gamma-ray emitter radionuclides in samples measured by HPGe gamma-ray spectrometry relies on the analysis of the photopeaks present in the spectra, especially on the accurate determination of their net areas. Such a task is usually performed with the aid of proprietary software tools. This work presents a methodology, algorithm descriptions and an open source application, called OpenGamma, for the peak search and analysis in order to obtain the relevant peaks parameters and radionuclides activities. The computational implementation is released entirely in open-source license for the main code and with the use of open software packages for interface design and mathematical libraries. The procedure for the peak search is performed on a three step approach. Firstly a preliminary search is done by using the second-difference method, consisting in the generation of a derived spectrum in order to find candidate peaks. In the second step, the experimental peaks widths are assessed and well formed and isolated ones are chosen to obtain a FWHM vs. channel relationship, by application of the Levenberg-Marquardt minimization method for non-linear fitting. Lastly, regions of the spectrum with grouped peaks are marked and a non-linear fit is again applied to each region to obtain baseline and photopeaks terms; from these terms, peaks net areas are then assessed. For the activity determination, previously obtained efficiency calibration curves, as well as nuclides gamma-ray data, are incorporated in the code and applied. The code was developed in C++ language and the interface was developed with Qt GUI software toolkit. GNU scientific library, GSL, was employed to perform fitting procedures as needed. Validation of code was done by analyzing: 1) synthetic test spectra from IAEA, especially designed for software performance evaluation; 2) spectra obtained from samples of intercomparison exercises and 3) spectra from routine activities of the Environmental Radiometric Laboratory (LRA) at IPEN and analyzed with the commercial software package InterWinner. Results obtained are consistent with the reference values and with those obtained by the aforementioned package. The results suggest that the OpenGamma code could be safely used in general-purpose gamma-ray spectrometry.

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This, Kélian. "Extraction semi-paramétrique de l’information issue de spectres gamma." Electronic Thesis or Diss., université Paris-Saclay, 2022. http://www.theses.fr/2022UPASG003.

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La spectrométrie gamma est une technique de mesure nucléaire répandue qui peut être utilisée pour détecter une source radioactive, identifier sa composition et quantifier son activité.Un spectre constitue un résultat de mesure brut qui n’est pas interprétable directement. L’analyse du spectre permet d’en extraire l’information utile.Pour répondre à la croissance du besoin de mesures, nous proposons dans ce mémoire une méthode automatique d’analyse des spectres, appelée Model based Full Spectrum Analysis (MFSA), qui permet d’unifier la résolution des différents problèmes d’analyse de spectre. La MFSA explique la mesure par reconstruction complète du signal en s’appuyant sur un modèle paramétrique pour le mélange de pics contenus dans le spectre.La présence d'un continuum non caractérisé dans le spectre est la principale difficulté de l'analyse. Si la MFSA met en exergue cette problématique, elle ne la résout pas seule.La solution complémentaire retenue dans ce mémoire repose sur la formulation du problème du continuum inconnu comme un problème de perception artificielle (comment percevoir un objet dans son environnement ?). Le critère dérivé de cette interrogation est finalement la proposition centrale de ce mémoire, pour laquelle la spectrométrie gamma apparaît comme un cas d'usage.Enfin, nous appliquons notre méthode sur des données simulées et sur des données réelles afin de valider les solutions proposées Gamma-ray spectrometry is a widespread nuclear measurement technique that can be used to detect a radioactive source, identify its composition and quantify its activity.A spectrum is a raw measurement result that is not directly interpretable. Analysis of the spectrum allows useful information to be extracted.To meet the growing need for measurements, we propose in this thesis an automatic method of spectrum analysis, called Model based Full Spectrum Analysis (MFSA), which unifies the resolution of different spectrum analysis problems. MFSA explains the measurement by full signal reconstruction based on a parametric model for the mixture of peaks in the spectrum.The presence of an uncharacterised continuum in the spectrum is the main difficulty of the analysis. While MFSA highlights this problem, it does not solve it alone.The complementary solution adopted in this thesis is based on the formulation of the unknown continuum problem as a problem of artificial perception (how to perceive an object in its environment?). The criterion derived from this question is finally the central proposal of this thesis, for which gamma spectrometry appears as a use case.Finally, we apply our method on simulated and real data in order to validate the proposed solutions

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Degrelle, Deborah. "Caractérisation numérique de la technique de spectrométrie gamma par simulation Monte-Carlo. Application à la datation d'échantillons envrionnementaux." Thesis, Bourgogne Franche-Comté, 2017. http://www.theses.fr/2017UBFCD004/document.

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Caractérisation numérique de la technique de spectrométrie gamma par simulation Monte-Carlo : Application à la datation d'échantillons environnementaux.Résumé :Afin d'optimiser la détermination de l'activité d'échantillons environnementaux, l'étalonnage en efficacité de la chaîne spectrométrique se doit d'être de bonne qualité. Le travail de cette thèse consiste à rassembler les problématiques principales : les phénomènes d'auto-absorption et de coïncidence. Ces effets sont traités par métrologie et simulation Monte-Carlo (MCNP6), impliquant la bonne modélisation préalable de nos détecteurs. Le problème d'auto-absorption est dominant lorsque le standard utilisé pour l'étalonnage en efficacité a des caractéristiques physico-chimiques différentes des échantillons. Un étalonnage numérique semble plus approprié et nous l'appliquons à une archive sédimentaire du lac de Longemer (France). Nous proposons une méthode nouvelle se basant sur une mesure expérimentale ajustée numériquement afin de déterminer le coefficient d'atténuation massique des échantillons. Il est alors possible de remonter à une composition chimique fictive qui permettra d'utiliser la simulation Monte-Carlo pour réaliser l'étalonnage. Ainsi, à 59,54 keV la correction de l'auto-absorption peut atteindre 24 %. Les phénomènes de coïncidence peuvent également être corrigés par simulation. Le logiciel ETNA permet cette correction mais ne permet pas la modélisation d'un détecteur puits. Dans le but de corriger l'efficacité de notre détecteur puits, possédant une géométrie propice aux coïncidences, nous utilisons le transfert de rendement qui lui est adaptable pour n'importe quelle géométrie. Les résultats par cette méthode sont validés par MCNP6 et Génie 2000 sur les énergies principales du 214Bi In order to improve the determination of environmental samples activity, the detector efficiency calibration must be reliable. These studies deal with the main issues in gamma-ray spectrometry: the self-absorption and the true coincidence summing effects (TCS). These phenomena are studied by metrology and Monte-Carlo simulation (MCNP6) that imply the faithful of our detector models in relation to the experimental device. The self-absorption problem is the main one when the used standard for efficiency calibration has not the same physical and chemical characteristics than samples. A numerical calibration seems to be more suitable and we apply it for Longemer lake archives (France). A new method is proposed where an experimental measurement is processed through numerical simulations to determine the mass attenuation coefficient of the samples. It makes it possible to define a virtual chemical composition to use Monte-Carlo simulation. Then the numerical calibration at 59.54 keV gives a 24% self-absorption correction. The TCS problems can also be corrected by simulation. The ETNA software can determine this correction but it doesn’t make the well type detector model possible, with a geometry conducive to TCS effects. With the aim of correcting the efficiency of our well detector, the efficiency transfer, which can be adjusted to any device, is used. The results with this method are validated by MCNP6 and Genie 2000 software on the main lines of 214Bi

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Zeman, Miroslav. "Experimentální výzkum urychlovačem řízených jaderných reaktorů pro thoriovou jadernou energetiku." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2015. http://www.nusl.cz/ntk/nusl-221267.

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The Master Thesis deals with the use of thorium nuclear fuel in accelerator driven systems. Basic principle of ADS, present situation and future possibilities are described in this work. The main goal of the work is determination of neutron flux in spallation target QUINTA. In December 2013, an experiment was performed at Joint Institute for Nuclear Research, Dubna. Samples of cobalt, situated at different positions in QUINTA target, were irradiated in secondary neutron field generated by deuteron beam of energies 2 AGeV and 4 AGeV and beam of C-12 with energy 2 AGeV. The samples were measured with the use of germanium semiconductor detectors and analysed using gamma-ray spectrometry. Reaction rates of Co-59 products were determined. Neutron flux was determined in setup QUINTA on the base of experimental reaction rates. Experimental reaction rates were compared with calcula1tion of MCNPX code.

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Erramli, Hassane. "Développement des techniques de dosimétrie appliquées à la datation par thermoluminescence." Clermont-Ferrand 2, 1986. http://www.theses.fr/1986CLF21045.

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Étude de la dosimétrie des rayonnements d'origine naturelle dans laquelle duex composantes peuvent être distinguées. Dose interne apportée par les rayonnements de faible parcours issus de l'échantillon considéré. Dose externe apportée par les rayonnements de grand pouvoir de pénétration et provenent de l'environnement de l'échantillon. Deux techniques sont traitées en détail: Dosimétrie thermoluminescents et spectrométrie gamma de terrain. Corrections liées à l'environnement et aux conditions d'emploi

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Dissertations / Theses on the topic 'Gamma-ray spectrometry'

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