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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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Chaisan, Kittisak. "Modelling the environmental transfers of radioactivity following the Fukushima accident." Thesis, University of Portsmouth, 2015. https://researchportal.port.ac.uk/portal/en/theses/modelling-the-environmental-transfers-of-radioactivity-following-the-fukushima-accident(60b31ec7-b843-4878-b374-931c5234b90c).html.
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After the massive tsunami on 11 March 2011, the explosions at 4 reactors of the Fukushima Daiichi (I) Nuclear Power Stations (Fukushima I NPSs) in Japan led to a large radioactive cloud being ejected into the atmosphere. Radionuclides released to the atmosphere were washed out in rain causing an area of remarkably high deposition in the area to the northwest of the Fukushima I NPSs. Activity remaining in the atmosphere was dispersed further to other areas of Japan. At various times during the accident, plumes of contamination were transported from Japan to the Pacific Ocean, the North American continent, crossing the Atlantic Ocean to Europe, and eventually to Asia. Due to the lack of measurements in three major ecosystem compartments i.e. air, soil and surface water, information on the highest impact early-phase after fallout and the interpretation of long-term impacts is limited and unclear. The transfer of contaminated radionuclides to soil and air around the Fukushima I NPSs was studied using ratios of various radioisotopes to the long-lived nuclide 137Cs. It was found that ratios of three radionuclides i.e. 134,136Cs and 132Te were consistent with direction and distance in air and soil while the ratio 131I/137Cs was not. It was shown that, deposited 131I/137Cs had an inverse correlation with 137Cs activity in soil. These nuclides were key in forming the high-gamma dose rates in the early phase, particularly the high gamma energy of 132I from the 132Te/132I decay. The derived ratios of these key radionuclides in soil were used together with available measured gamma dose rates in the early phase (< 30 days) to develop a model to reconstruct and predict external gamma dose rate. Model “blind” tests showed that more than 95% of predictions were within a factor of two of measurements from 15 sites to the north, northwest and west of the power station. It is demonstrated that generic isotope ratios provide a sound basis for reconstruction of early-phase external dose rates in these most contaminated areas. For contamination in surface runoff water, lake water and fish, a previous model developed following the Chernobyl accident (AQUASCOPE) was applied to the Fukushima situation. It was shown that by adjusting for the stronger absorption of radiocaesium in soils in Japan (compared with European countries) the model could be used successfully to predict long-term contamination in aquatic systems affected by Fukushima fall out. The results of the model showed good agreement with measured data, in particular in the long-term period (around 0.5-2 years) after the accident.
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Gould, Travis J. "Measuring and Modeling Exposure from Environmental Radiation on Tidal Flats." Fogler Library, University of Maine, 2004. http://www.library.umaine.edu/theses/pdf/GouldTJ2004.pdf.
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Tanha, Mohammad Rahmatullah [Verfasser]. "Environmental radioactivity studies in Kabul and northern Afghanistan / Mohammad Rahmatullah Tanha." Hannover : Technische Informationsbibliothek (TIB), 2017. http://d-nb.info/1166269051/34.
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Evans, Ellis Induro. "Environmental characterisation of particle-associated radioactivity deposited close to the Sellafield works." Thesis, Imperial College London, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285387.
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The calculation of dry particle deposition velocity (Vg) for small particles in field studies is subject to much variability between theoretical and measured values. This work will assess some of the factors which may influence the calculation of Vg. The other key parameter which is used to define the near-surface exchange of material is the resuspension factor (K). The certainty of using a Vg which is representative of small particles typically 1 pm requires clarification. During September 1993-1994, four size-selective air and deposition experiments were carried out at an on-site and off-site sampling location close to the BNFL Sellafield nuclear reprocessing plant in Cumbria UK. Dry and total (wet & dry) particle deposition velocities were determined for ^^^Cs, The dry deposition velocities of naturally-occurring ^Be were also determined and used as a 'marker' for small particle transport processes. Resuspension factors K (m ^) for radiocaesium and Plutonium were also derived. Automated individual particle characterisation (AlP) using scanning electron microscopy coupled to energy-dispersive x-ray analysis (SEM-EDXA) was used to determine the particle size distribution and associated elemental composition of material deposited to Frisbee deposition collectors. Enhanced a-emitting hot-spots from surface soils and material deposited to Frisbee collectors at 1 m above ground level were isolated and characterised for size and shape using nuclear track detector film, LR-115. Dry particle deposition velocities for ^^^Cs, 239+240py and were commonly in excess of 1E-03 m s"^ by more than two orders of magnitude. Total deposition velocities (dry and wet) were even higher with values ranging from 0.2 m s^ -1 ms"^ for both radiocaesium and plutonium. High derived values of dry deposition velocity for radiocaesium and plutonium were to some extent influenced by air sampling artefacts. Air sampling artefacts result in an under-estimation of airborne activity for radioactivity associated with particle diameters >10 pm. The derived values of dry particle deposition velocity for ^Be were consistent with literature values of sub-micron sized particles with evidence of a seasonal spring maximum. Resuspension factors K (m'^) for radiocaesium and plutonium agreed well with literature values of weathered weapons fallout values which ranged from 2E-08 to 5E-11 (m"^) for plutonium and radiocaesium respectively. Differences in dry particle deposition velocities for radiocaesium and plutonium between the on-site and off-site locations varied by no more than a factor of three. Correlations between dry particle deposition velocities for Cs and Pu with wind speed, wind direction and precipitation rates were not found. Size-specific air sampling show that the majority of the plutonium was predominantly associated with the >11 lam aerosol size fraction. The association between activity and large particle size suggest this material was probably attached to large soil-derived particles. Plutonium isotope data indicate this material originated fromthe nuclear weapons programme of the late 1950's-earty 1970's. Radiocaesiumactivities were equally distributed between the < 10 ixm and > 11 ^m aerosol fractions for two out of the four runs. This suggests that historically deposited ''^^Cs and current emissions contributed to measured airborne activities. Enhanced a-emitting hot-spots were isolated from bulk surface soils and in material deposited to Frisbee collectors. Rare particles such as these with atypical activities of Pu may lead to mis-leadingly high deposition fluxes. The calculation of Vg in the field is therefore sensitive to the presence of these particles because they are not representative of the aerosol flux and their size s 50 |im precludes their collection by the Pmio air sampler. The main conclusions of this work indicates the very high values of Vg sometimes measured in the field are strongly influenced by large resuspended soil particles and associated air sampling artefacts. The inclusion of large particles within the deposition flux is confirmed by size selective mass based Vg using scanning electron microscopy
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Bulala, Avuyile Sisanda. "Efficiency calibration of a gamma-ray detector for measuring environmental radiation." Master's thesis, University of Cape Town, 2020. http://hdl.handle.net/11427/32467.
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The Environmental Radioactivity Laboratory (ERL) of iThemba LABS conducts research into levels of natural and anthropogenic radioactivity in the environment. The laboratory-based measurements are conducted using a low-background Hyper Pure Germanium (HPGe) detector system. A critical aspect of such measurements involves calibrating the detector about energy and detection efficiency. The present study details experiment that were carried to determine both energy and efficiency calibrations for various sample geometries using gamma-ray spectrometry. The measurements using reference sources of known activity were carried out using two sample holders (Marinelli Beaker (1000 ml) and, a cylindrical pill bottle (100 ml)), and a point source. The IAEA reference materials (RGU-1, RGTh-1 ore and RGK-1) were prepared and used to fill the Marinelli beaker and pill bottles. Certified reference point sources (⁶⁰Co, ¹⁵²Eu, ¹³⁷Cs, ²²Na, ²⁴¹Am and ¹³³Ba) were obtained from the National Metrology Institute of South Africa (NMISA). Experiments consisted of exposing the HPGe detector to various gamma-ray sources prepared using various sample holders and the point source geometry. The counting time for each measurement was 24 hours. Each spectrum was analysed by inserting region of interests around suitably selected photo-peaks and the counts associated with these photo-peaks were automatically determined and corrected for background by the software. The full energy peak detection efficiency was then determined from the background corrected counts, the known activity of the source and the implicit in measurement (solid angle). The experimental and simulated spectra using point sources and volume sources were compared. Both experimental and simulated spectra presented showed a good agreement in terms of shape and varying intensities as expected. Additional photo-peaks were observed from ²²Na, ⁶⁰Co, ¹³³Ba and ¹⁵²Eu (point sources) and ²³²Th and ²³⁸U (volume sources) experimental spectra these effects were not observed in the simulated spectra. These additional peaks observed are the result of coincidence summing in some of gamma emitting radionuclides. Efficiencies that were experimentally determined, were compared with the calculated efficiencies from Monte Carlo simulations using MCNPX. Efficiency calibration parameters (power fit function) for the volume sources were determined from experimental and simulated data; a = 2.58; b = -0.75 experimental and a = 1.01; b = 0.65 simulated (100 mL pill bottle) and a = 2.07; b = -0.75 experimental and a = 1.61; b = 0.66 simulated (1 L Marinelli beaker). The simulated parameters for the efficiency as determined can be used for future calculations of activity concentrations when the 100 mL pill bottle or 1 L Marinelli Beaker sample holder is used. Further improvement in these calculations can be achieved by considering the sample density. The simulation input files used to generate these values is available and can be modified to match any sample holder geometry, as well as any density that might be required in future counting.
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Chiu, Yu-yeung. "Environmental radiation monitoring at the low level radioactive waste storage facility in Siu A Chau and development of a particle dispersion model in marine environment." Click to view the E-thesis via HKUTO, 2006. http://sunzi.lib.hku.hk/hkuto/record/B38573611.
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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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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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Maphoto, Katse Piet. "Determination of natural radioactivity concentrations in soil: a comparative study of Windows and Full Spectrum Analysis." Thesis, University of the Western Cape, 2004. http://etd.uwc.ac.za/index.php?module=etd&.
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In this study, two methods of analysing activity concentrations of natural radionuclides (U, Th and K) in soil are critically compared. These are the Window Analysis (WA) and Full Spectrum Analysis (FSA). In the usual WA method, the activity concentrations are determined from the net counts of the windows set around individual &gamma-ray peaks associated with the decay of U, Th and K. In the FSA method, the full energy spectrum is considered and the measured spectrum is described as the sum of the three standard spectra (associated with U, Th and K, respectively), each multiplied by an unknown concentration. The concentrations are determined from the FSA and correspond to the activity concentrations of U, Th and K in the soil. The standard spectra derived from separate calibration measurements using the HPGe detector, represents the response of the HPGe to a Marinelli sample beaker containing an activity concentration of 1 Bq/kg.
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Chiu, Yu-yeung, and 趙汝揚. "Environmental radiation monitoring at the low level radioactive waste storage facility in Siu A Chau and development of a particledispersion model in marine environment." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2006. http://hub.hku.hk/bib/B38573611.
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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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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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TEIXEIRA, WASHINGTON E. "Determinacao das concentracoes dos isotopos naturais de Ra em amostras costeiras do litoral norte do estado de Sao Paulo." reponame:Repositório Institucional do IPEN, 2004. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11173.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Joseph, Angelo Daniel. "Radiometric study of soil: the systematic effects." Thesis, University of the Western Cape, 2007. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_6805_1248251582.
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The natural ²
³
â¸U, ²
³
²
Th and â´°
K radioactive content of vineyard soil was measured with an in-situ gamma-ray detector. The activity concentration measured with the in-situ detector are normalized using the laboratory-determined activity concentrations of several samples from the vineyard site. To determine the activity concentration of a particular soil sample, the gamma-ray photopeak detection efficiencies are required. In this work, the detection efficiencies were derived for each soil sample using gamma-ray photopeaks associated with the radionuclide of ²
³
â¸U, ²
³
²
Th present in the sample, and the â´°
K, 1460.8 keV gamma-ray peak, from KCl salt.
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SILVA, PAULO S. C. da. "Caracterizacao quimica e radiologica dos sedimentos do estuario de Santos, Sao Vicente e Baia de Santos." reponame:Repositório Institucional do IPEN, 2004. http://repositorio.ipen.br:8080/xmlui/handle/123456789/11215.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
FAPESP:99/06952-4
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Thomas, Vincent. "Développement d’un système de mesure ultra-compact à coïncidences électron/photon pour la détection et la caractérisation de radionucléides du xénon." Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLS454/document.
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Dans le cadre du Traité d'Interdiction Complète des Essais Nucléaires (TICE), le Système de Surveillance International (SSI) a été développé. Ce réseau consiste en plusieurs centaines de stations de mesures dont le rôle est de détecter la signature d'un essai nucléaire clandestin. Quatre types de mesures sont effectués: sismique, hydro-acoustique, infrason et radionucléide. Dans le cas particulier d'un essai nucléaire souterrain, seule la mesure des radionucléides est adéquate pour mettre en évidence le caractère nucléaire de l'explosion. Quatre radionucléides du xénon sont produits en masse lors d'un essai nucléaire: le 131m-Xe, le 133m-Xe, le 133-Xe, et le 135-Xe. Une faible proportion de ces gaz parvient à diffuser à travers les fissures de la cavité et se retrouver dans l'atmosphère. A cause de la dilution atmosphérique, les concentrations de ces quatre radionucléides sont extrêmement faibles et par conséquent difficiles à détecter. De plus, le bruit de fond atmosphérique ne cesse d'augmenter car ces gaz radioactifs sont également produits et relâchés par les usines de production de radio-isotopes médicaux et les centrales nucléaires. Afin de renforcer le réseau de surveillance, le CEA-DAM a proposé de développer un système de détection des radionucléides du xénon ultra-compact et mobile, afin de pouvoir effectuer des mesures de vérification directement sur site suspect, et ainsi contourner la contrainte de dilution atmosphérique. Ces travaux présentent le développement et l'optimisation de ce système. Le système a d'abord été modélisé sur ordinateur et ses performances en terme d'efficacité de détection ont été simulées par méthode de Monte-Carlo avec le logiciel Geant4. Les mesures se font en utilisant la technique de mesure en coïncidences électron/photon. En parallèle, une chaîne d'acquisition ultra-compacte a été développée, ainsi qu'un réseau de communication permettant de synchroniser en temps les différents spectromètres numériques utilisés pour le traitement du signal (protocole IEEE 1588 PTP). Les concentrations minimales détectables de ce système sont inférieures à 5 mBq/m³ pour une acquisition de 12 h, et ce pour les quatre radionucléides du xénon d'intérêtAs part of the Comprehensive nuclear Test Ban Treaty (CTBT), an International Monitoring System (IMS) has been developed. This network consists of several hundred measuring stations whose role is to detect the signatures of a clandestine nuclear test. Four types of measurements are carried out: seismic, hydroacoustic, infrasound and radionuclide. In the particular case of an underground nuclear test, only the radionuclide measurement is adequate to detect the explosion and quantify its yield. Four xenon radionuclides with long half-lives are produced during a nuclear test: the 131m-Xe, the 133m-Xe, the 133-Xe and the 135-Xe. A small proportion of these gases may diffuse through the cracks in the cavity and end up in the atmosphere. Due to atmospheric dilution, the concentrations of these four radionuclides are extremely low and therefore difficult to detect. In addition, atmospheric background continues to increase as these radioactive gases are also produced by medical radioisotope facilities and nuclear power plants. In order to strengthen the IMS, the CEA-DAM has proposed to develop an ultra-compact and mobile system for detecting xenon radionuclides, in order to be able to carry out verification measurements directly on site, and thus to avoid the problem of atmospheric dilution. This work presents the development and optimization of this system. The system was first modelled on a computer and its performances in terms of detection efficiency were simulated by the Monte-Carlo method using Geant4 software. Measurements are made in electron-photon coincidence mode. In parallel, an ultra-compact acquisition chain has been developed, as well as a communication network to synchronize in time the various digital spectrometers used for signal processing (IEEE 1588 PTP protocol). The minimum detectable concentrations of this system are less than 5 mBq/m³ for a 12 h acquisition, for the four xenon radionuclides of interest
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MacDonald, Julian. "Analysis of '1'3'7Cs contamination in soil using in-situ gamma spectrometry." Thesis, Bangor University, 1999. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.297869.
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SZELES, MARLENE S. M. F. "Avaliacao da contaminacao radiologica de um solo agricola nas proximidades de uma mina de uranio." reponame:Repositório Institucional do IPEN, 1994. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10434.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Truscott, Jason Bedford. "Determination of actinide elements in environmental samples by ICP-MS." Thesis, University of Plymouth, 2000. http://hdl.handle.net/10026.1/490.
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Methods for the determination of the actinide elements in water, biological, soil and sediment samples have been developed using on-line solid phase extraction and high performance liquid chromatography (HPLC) coupled with inductively coupled plasma mass spectrometry (ICP-MS). Initial applications utilised a commercially available resin, namely TRU-Spec resin, for efficient removal of the matrix prior to elution of uranium and thorium analytes. Comparative analyses of reference materials and natural water samples from Plymouth and Dartmoor demonstrated significant improvement in precision and speed of analysis by using TRU-Spec coupled to ICP-MS compared with alpha spectrometry. Further applications of the TRU-Spec resin for the determination of the transuranic actinide elements neptunium, plutonium and americium, resulted in the successful determination of 239Pu and 237Np in biological reference materials. Detection limits were 700, 850, and 600 attograms (ag) for 237Np, 233Pu, and 241Am, respectively, for a 0.5 ml sample injection, and better than 200 ag/g with 50 ml pre-concentration when sector field (SF) ICP-MS was used. A method for the selective sequential elution of uranium and plutonium was also developed to facilitate the determination of 239Pu without interference due to the 238U1H+ polyatomic ion, caused by high concentrations of 238U in sediment samples. Investigations were performed into the use of a polymeric substrate, which was dynamically coated with chelating dyes such as xylenol orange and 4-(2-pyridylazo) resorcinol, and a silica substrate coated with permanently bonded iminodiacetic acid. The latter was used for the successful determination of uranium and thorium in certified reference material waters. However, the column was found to have a high affinity for iron, making it unsuitable for the determination of the actinides in soil and sediment samples. Subsequently, a polystyrene substrate which was dynamically coated with dipicolinic acid was used for HPLC coupled with SF-ICP-MS. Using this column it was possible to separate the various actinides from each other and from the matrix. In particular, it was possible to separate plutonium and uranium to facilitate interference-free determination of the former. The column also exhibited some selectivity for different oxidation states of Np, Pu and U. Two oxidation states each for plutonium and neptunium were found, tentatively identified as Np(V) and Pu(III) eluting at the solvent front, and Np(IV) and Pu(IV) eluting much later. Detection limits were 12, 8, and 4 fg for 237Np, 239Pu, and 241Am, respectively, for a 0.5 ml injection, and the system was successfully used for the determination of 239Pu in water, biological and soil reference materials.
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DAMATTO, SANDRA R. "Radionuclideos naturais da series do sup(238)U e sup(232)Th, elementos traco e maiores determinados em perfis de sedimento da Baixada Santista para avaliacao de areas impactadas." reponame:Repositório Institucional do IPEN, 2010. http://repositorio.ipen.br:8080/xmlui/handle/123456789/9574.
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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP
22
SANTOS, Nandízia Fernanda Tavares dos. "Biomonitoração de urânio e tório em moradores de áreas anômalas e adjacentes do estado da Paraíba." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/18341.
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CAPES
A elevada concentração de urânio e tório no meio ambiente possibilita maior exposição do homem aos radionuclídeos naturais, necessitando assim, de avaliação devido aos riscos potenciais à saúde humana. No estado da Paraíba, no município de São José de Espinharas, encontra-se uma reserva de urânio, expondo, assim, seus habitantes. Amostras biológicas como cabelo e sangue podem ser utilizadas como bioindicadores para populações expostas, natural ou ocupacionalmente. O presente estudo visou a biomonitoração desses elementos em humanos, através de amostras de cabelo e sangue utilizando o ICP-MS. As concentrações sanguíneas dos doadores apresentaram-se bastante reduzidas, inferiores ao limite de detecção (0,001µg. g-1) para a metodologia proposta. Entretanto, as concentrações de urânio e tório no cabelo para os habitantes de São José de Espinharas variaram de 3,27 a 191,50 µg.g-1 e 0,30 a 9,44 µg.g-1, com médias de 20,73 µg.g-1 e 3,72 µg.g-1, respectivamente. Foram avaliados também, municípios adjacentes, sendo eles: São Mamede, São José do Sabugi e Patos. Os intervalos de concentração e as médias encontradas foram: para urânio de 10,10 a 337,20 µg.g-1 (187,24 µg.g-1 ), 17,87 a 362,38 µg.g-1 (120,90 µg.g-1 ) e 4,08 a 0,30 µg.g-1 ( 7,31 µg.g1 ); e para tório de 0,05 a 21,01 µg.g-1 (5,45 µg.g-1), 0,08 a 6,41 µg.g-1 (2,08 µg.g-1), 0,23 a 7,23 µg.g-1 (4,09 µg.g-1), respectivamente. A média geral do referido estudo foi de 68 µg.g-1 para urânio, e 3,61 µg.g-1 para o tório. Indivíduos cujas concentrações de urânio encontram-se inferiores a 100 µg.g-1 podem ser considerados como não expostos. Demonstrando este fato, os resultados de urânio e tório sérico, indicaram ausência desses elementos na corrente sanguínea. Entretanto, em amostras de cabelo, alguns doadores apresentaram concentrações superiores a este valor, necessitando assim de avaliações adicionais em matrizes diferentes, para testes confirmatórios. Concentrações de tório em cabelo são pouco pesquisadas, não havendo valores para referência. Sugerem-se análises das águas e alimentos para maiores esclarecimentos da exposição e possível intoxicação, visto que, são fontes importantes de contaminação.
The high concentration of uranium and thorium in the environment allows for greater human exposure to natural radionuclides, thus requiring, evaluation of the potential risks to human health. In the state of Paraíba, in São José de Espinharas is a uranium reserves, thereby exposing its inhabitants. Biological samples such as hair and blood can be used as bioindicators of exposed populations, natural or occupationally. The present study aimed biomonitoring of these elements in humans, through hair and blood samples using ICP-MS. Blood concentrations of the donors had to be quite low, below the detection limit (0.001µg. g1 ) for the proposed methodology. However the concentrations of uranium and thorium hair for the inhabitants of São José de Espinharas ranged from 3.27 to 191.50 μg.g-1 and 0.30 to 9.44 μg.g-1, with an average of 20.73 μg.g-1 and 3.72μg.g-1, respectively. Were also evaluated, adjacent municipalities, namely: São Mamede, São José do Sabugi and Patos. The concentration ranges and averages were: uranium to 10.10 to 337.20 μg.g-1 (187.24 μg.g-1), 17.87 to 362.38 μg.g-1 (120.90 μg.g-1) and 4.08 to 0.30 μg.g-1 (7.31 μg.g-1); and thorium from 0.05 to 21.01 μg.g-1 (5.45 μg.g-1), 0.08 to 6.41 μg.g-1 (2.08 μg.g-1), 0.23 to 7.23 μg.g-1 (4.09 μg.g-1), respectively. The overall average of the study was 68 μg.g-1 for uranium, and 3.61 μg.g-1 for thorium. Individuals whose uranium concentrations are below 100 μg.g-1 can be considered unexposed. Demonstrating this fact, the results of uranium and thorium serum, demonstrating the absence of these elements in the bloodstream. However, in hair samples, some donors presented concentrations greater than this value, thus requiring additional assessments in different matrices, for confirmatory tests. Thorium concentrations in hair are little studied, with no values for reference. It is suggested analyzes of water and food for more exposure clarification and possible poisoning, as are important sources of contamination.
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Borrelli, Robert Angelo. "Characterization of Radioactivity in the Environment." Digital WPI, 1999. https://digitalcommons.wpi.edu/etd-theses/1085.
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"Ionizing radiation is produced as the result of the decay of an unstable nucleus. The standard measure of radioactivity is quantified according to the rate of disintegration of the unstable nucleus. This method of quantification does not incorporate the total amount of ionizing radiation that is associated with each disintegration of the radionuclide. The ionizing radiation that is produced as a result of decay is specific to a given radionuclide. A radionuclide can be conceptualized as a source of ionizing radiation. Disintegration of the unstable nucleus will therefore result in the continual release of ionizing radiation throughout the fixed existence of the radionuclide. This thesis will present a reasonable and practical adjustment to the current mechanism regarding the quantification of radionuclides. This adjustment will provide a basis to which the specific decay attributes of radionuclides can be normalized. Such a normalization will allow for direct comparisons among important inventories of radionuclides. This adjustment will be used to formulate a characterization of common radionuclides that exist in the environment. Such a characterization can provide a control inventory of ionizing radiation to which more specific systems of radionuclides can be compared."
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Doering, Che. "Measurements of the distribution and behaviour of Beryllium-7 in the natural environment." Thesis, Queensland University of Technology, 2007. https://eprints.qut.edu.au/16513/1/Che_Doering_Thesis.pdf.
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Beryllium-7 is a cosmogenic radionuclide produced in the atmosphere through the spallation of nitrogen and oxygen nuclei by cosmic-ray-produced neutrons and protons. It is carried in the atmosphere attached to aerosols and is deposited on land and ocean surfaces by wet and dry deposition processes. Beryllium-7 decays by electron capture to lithium-7 and has a half-life of approximately 53 days. It is a potentially useful radionuclide for studying different natural processes.
This thesis presents a collection of scientific papers on the occurrence of beryllium-7 in the natural environment, particularly in the Southeast Queensland region of Australia. It shows the results of experimental measurements and discusses their implications. Overall, this thesis contributes to advancing our understanding of the distribution and behaviour of beryllium-7 in the natural environment and provides a foundation for the development of nuclear techniques for the evaluation of environmental problems.
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Doering, Che. "Measurements of the distribution and behaviour of Beryllium-7 in the natural environment." Queensland University of Technology, 2007. http://eprints.qut.edu.au/16513/.
Full textAbstract:
Beryllium-7 is a cosmogenic radionuclide produced in the atmosphere through the spallation of nitrogen and oxygen nuclei by cosmic-ray-produced neutrons and protons. It is carried in the atmosphere attached to aerosols and is deposited on land and ocean surfaces by wet and dry deposition processes. Beryllium-7 decays by electron capture to lithium-7 and has a half-life of approximately 53 days. It is a potentially useful radionuclide for studying different natural processes. This thesis presents a collection of scientific papers on the occurrence of beryllium-7 in the natural environment, particularly in the Southeast Queensland region of Australia. It shows the results of experimental measurements and discusses their implications. Overall, this thesis contributes to advancing our understanding of the distribution and behaviour of beryllium-7 in the natural environment and provides a foundation for the development of nuclear techniques for the evaluation of environmental problems.
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SERAFINI, Andrea. "Exploiting 40K radioactivity to probe the Earth and the environment." Doctoral thesis, Università degli studi di Ferrara, 2022. http://hdl.handle.net/11392/2481668.
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Il potassio è l'ottavo elemento più abbondante nella crosta terrestre. Tra i suoi isotopi naturali il potassio ha un radionuclide, il potassio-40 (40K), che ha un'emivita di oltre un miliardo di anni e che ha avuto un ruolo attivo nell'evoluzione del nostro pianeta. Nei suoi decadimenti, 40K produce elettroni, positroni, fotoni, neutrini e antineutrini attraverso catture elettroniche, decadimenti beta e transizioni gamma. Un radionuclide così abbondante con una dinamica di decadimento così varia offre la possibilità di sondare la Terra su diverse scale spaziali. Durante il suo decadimento, 40K genera calore. Insieme all'uranio-238 (238U) e al torio-232 (232Th), si stima che questi radionuclidi producano ancora oggi metà del calore a disposizione dei processi interni del nostro pianeta.
Tra i prodotti del 40K, gli antineutrini sono di particolare interesse per lo studio del nostro pianeta. Queste particelle possono viaggiare indisturbate per migliaia di chilometri, rendendole preziose messaggere nella comprensione della Terra interna. Lo studio di questi “geoneutrini”, prodotti all'interno della Terra nei decadimenti di 40K e nelle catene di decadimento di 238U e 232Th, permette di recuperare informazioni sulla composizione e sul bilancio energetico del nostro pianeta. In questa tesi, combinando i risultati sperimentali di KamLAND e Borexino, ho stimato la produzione di calore radiogenico del mantello terrestre. Il segnale sperimentale da geoneutrini di 238U e 232Th è stato analizzato alla luce degli attuali modelli geochimici per derivare la produzione di calore radiogenico del nostro pianeta e il contributo complementare dovuto al lento raffreddamento terrestre. Sebbene questi risultati pongano già vincoli all’energetica della Terra, le attuali tecniche di rilevamento non consentono l'osservazione di geoneutrini da 40K, limitando le nostre conoscenze a ipotesi fortemente dipendenti da modelli teorici. In questo lavoro ho proposto un nuovo metodo di rivelazione basato sulla doppia coincidenza offerta dall'interazione di antineutrini su nuclei di 63Cu. Ho mostrato come questa tecnica potrebbe essere sfruttata in un rivelatore da 240 kton per rivelare i geoneutrini da 40K con una significatività di 5σ in 10 anni di acquisizione dati, consentendo di indagare questa regione dello spettro dei geoneutrini ancora inesplorata.
Oltre a questi studi, volevo avere un impatto concreto nel presente, concentrandomi sull'applicazione di tecniche di spettroscopia gamma all'agricoltura di precisione. L'agricoltura rappresenta da sola più della metà dei prelievi idrici globali. Un miglioramento delle pratiche agricole è quindi di fondamentale importanza per assicurare una gestione sostenibile dell'acqua. I fotoni emessi nelle transizioni gamma di 40K possono viaggiare per decine di centimetri e metri nel suolo e nell'aria, conservando preziose informazioni sull'ambiente che ci circonda. In questo lavoro l'evoluzione temporale del segnale gamma da 40K misurato da una stazione spettroscopica installata in un campo sperimentale è stata analizzata per recuperare indirettamente il contenuto idrico del suolo. La dipendenza del coefficiente di attenuazione lineare del suolo dalla quantità d’acqua immagazzinata nel terreno è stata sfruttata per stimare in tempo reale l'umidità del suolo con una scala spaziale di 25m. Contemporaneamente, l'analisi della variazione temporale dei conteggi osservati nella finestra energetica del 214Pb, un prodotto del radon che arricchisce l'acqua piovana, si è dimostrata efficace nel discernere gli episodi di pioggia dall'irrigazione. La capacità di misurare il contenuto idrico del suolo su scala di campo unita alla capacità di distinguere l'acqua piovana dall'irrigazione, diventerà sempre più importante nel contesto di un'agricoltura progressivamente più automatizzata, consentendo alla spettroscopia gamma di riempire un divario spaziale ancora aperto tra sensori puntuali e satelliti.Potassium is the 8th most abundant element in Earth’s crust. Among its natural isotopes potassium has a radionuclide, potassium-40 (40K), which has a half-life of more than a billion years, and which had an active role in the development of our planet. During its decays, 40K produces electrons, positrons, photons, neutrinos, and antineutrinos through electron captures, plus and minus beta decays and gamma transitions. A so abundant radionuclide with such a varied decay dynamics offers the possibility to probe the Earth on different spatial scales. While decaying, 40K generates heat. Together with uranium-238 (238U) and thorium-232 (232Th), it is estimated that these radionuclides still produce half of the heat available to the internal processes that regulate the dynamics of our inner planet. Among 40K decay products, antineutrinos are of particular interest for studying our planet. These particles can travel undisturbed for millions of kilometers, making them valuable messengers in the comprehension of the inner Earth. The study of these “geoneutrinos”, produced inside the Earth in the decays of 40K and in the decay chains of 238U and 232Th, allow us to recover information on the composition and on the energy budget of Earth’s mantle. One of the most relevant results of my thesis was the estimation of Earth’s radiogenic heat production from the combination of KamLAND and Borexino experimental results. The measured geoneutrino signal coming from 238U and 232Th decays was analyzed in view of present geochemical models to estimate the total radiogenic heat production of our planet and in turn to derive the complementary heat loss contribution due to secular cooling, providing a global vision on the heat sources which power our planet. Although already posing constraints on the internal heat production of the Earth, current detection techniques do not permit the observation of 40K geoneutrinos, restricting our knowledge on Earth's energetics to model dependent assumptions. I proposed in this work a novel detection method based on the double coincidence offered by the interaction of antineutrinos on 63Cu nuclei. I showed how this technique could be exploited in a 240 ktons detector to enable the 40K geoneutrino detection at 5σ level in 10 years of data taking, possibly permitting to uncover this yet unexplored region of the geoneutrino spectrum. Besides these studies, I wanted to have a concrete impact in the present, focusing on the study and application of gamma spectroscopy techniques to precision agriculture. Agriculture accounts by itself for more than half of global water withdrawals. Improvement of farming practices is thus imperative for a meaningful climate action and for ensuring a sustainable management of water. The photons emitted in 40K gamma transitions can travel for tens of centimeters and meters in matter and air, respectively, and retain precious information on the environment which surround us. In this work, the temporal evolution of the 40K gamma signal measured by a dedicated spectroscopic station installed in a test field was analyzed to indirectly recover soil water content. The dependence of soil’s linear attenuation coefficient on the amount of water stored in the ground was exploited to recover real time insights on soil moisture with a ∼25m footprint. Simultaneously, the analysis of transient increases in the spectral energy window of 214Pb, a radon daughter enriching rainwater, was shown to be effective in discerning rain episodes from irrigation. The capability to measure soil water content at field scale coupled to the ability to distinguish rainwater and irrigation will become increasingly important in the context of a progressively more automated smart agriculture, allowing gamma spectroscopy to fill a still unbridged spatial gap between punctual sensors and satellites.
27
Cox, Glen Michael. "Managing radioactively contaminated land : a method to assist the design of long-term remediation strategies." Thesis, University of Nottingham, 2004. http://eprints.nottingham.ac.uk/10085/.
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This thesis describes the development of a system to assist the design of long-term remediation strategies for radioactively contaminated land. Existing radiological models, that estimate the uptake of radionuclides by plants and the doses arising from exposure to external radiation, were combined with a spatially implemented food-chain model, to allow the temporal and spatial variation of radionuclide transport through the terrestrial environment, and the resulting doses of exposed human populations, to be estimated. Doses are estimated using a novel method for the simulation of human populations, which includes the generation of sub-populations by Monte-Carlo sampling and consideration of the geographical origins of consumed food products. Various simulated radiological countermeasures have been incorporated into the system (e.g. clean-feeding of livestock), allowing the effects of potential remediation strategies to be assessed. Furthermore, a method has been developed which efficiently identifies the optimum set of countermeasures for a given scenario according to a defined merit function using cost benefit analysis, which can be extended to include terms that account for the preference for averting high levels of individual dose, and the social costs of a number of countermeasure side-effects (e.g. disruption of normal daily life). To assess the applicability of the system, it was used to evaluate potential remediation strategies for hypothetical, large-scale nuclear accidents within two contrasting case study sites (Cumbria, UK and Zaragoza, Spain). In both case studies the system successfully identified optimal remediation strategies which were, according to the defined merit function, significant improvements upon simple food and dose rate restriction strategies.
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Lawrence, Cameron Eoin. "Measurement of 222Rn Exhalation Rates and 210Pb Deposition Rates in a Tropical Environment." Thesis, Queensland University of Technology, 2006. https://eprints.qut.edu.au/16291/1/Cameron_Lawrence_Thesis.pdf.
Full textAbstract:
This thesis provides the measurements of 222Rn exhalation rates, 210Pb deposition rates and excess 210Pb inventories for locations in and around Ranger Uranium Mine and Jabiru located within Kakadu National Park, Australia. Radon-222 is part of the natural 238U series decay chain and the only gas to be found in the series under normal conditions. Part of the natural redistribution of 222Rn in the environment is a portion exhales from the ground and disperses into the atmosphere. Here it decays via a series of short-lived progeny, that attach themselves to aerosol particles, to the long lived isotope 210Pb (T1/2 = 22.3 y). Attached and unattached 210Pb is removed from the atmosphere through wet and dry deposition and deposited on the surface of the earth, the fraction deposited on soils is gradually transported through the soil and can create a depth profile of 210Pb. Here it decays to the stable isotope 206Pb completing the 238U series.
Measurements of 222Rn exhalation rates and 210Pb deposition rates were performed over complete seasonal cycles, August 2002 - July 2003 and May 2003 - May 2004 respectively. The area is categorised as wet and dry tropics and it experiences two distinct seasonal patterns, a dry season (May-October) with little or no precipitation events and a wet season (December-March) with almost daily precipitation and monsoonal troughs. November and April are regarded as transitional months. As the natural processes of 222Rn exhalation and 210Pb deposition are heavily influenced by soil moisture and precipitation respectively, seasonal variations in the exhalation and deposition rates were expected. It was observed that 222Rn exhalation rates decreased throughout the wet season when the increase in soil moisture retarded exhalation. Lead-210 deposition peaked throughout the wet season as precipitation is the major scavenging process of this isotope from the atmosphere.
Radon-222 is influenced by other parameters such as 226Ra activity concentration and distribution, soil porosity and grain size. With the removal of the influence of soil moisture during the dry season it was possible to examine the effect of these other variables in a more comprehensive manner. This resulted in categorisation of geomorphic landscapes from which the 222Rn exhalation rate to 226Ra activity concentration ratios were similar during the dry season. These results can be extended to estimate dry season 222Rn exhalation rates from tropical locations from a measurement of 226Ra activity concentration.
Through modelling the 210Pb budget on local and regional scales it was observed that there is a net loss of 210Pb from the region, the majority of which occurs during the dry season. This has been attributed to the fact that 210Pb attached to aerosols is transported great distance with the prevailing trade winds created by a Hadley Circulation cell predominant during the dry season (winter) months. By including the influence of factors such as water inundation and natural 210Pb redistribution in the soil wet season budgeting of 210Pb on local and regional scales gave very good results.
29
Lawrence, Cameron Eoin. "Measurement of 222Rn Exhalation Rates and 210Pb Deposition Rates in a Tropical Environment." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16291/.
Full textAbstract:
This thesis provides the measurements of 222Rn exhalation rates, 210Pb deposition rates and excess 210Pb inventories for locations in and around Ranger Uranium Mine and Jabiru located within Kakadu National Park, Australia. Radon-222 is part of the natural 238U series decay chain and the only gas to be found in the series under normal conditions. Part of the natural redistribution of 222Rn in the environment is a portion exhales from the ground and disperses into the atmosphere. Here it decays via a series of short-lived progeny, that attach themselves to aerosol particles, to the long lived isotope 210Pb (T1/2 = 22.3 y). Attached and unattached 210Pb is removed from the atmosphere through wet and dry deposition and deposited on the surface of the earth, the fraction deposited on soils is gradually transported through the soil and can create a depth profile of 210Pb. Here it decays to the stable isotope 206Pb completing the 238U series. Measurements of 222Rn exhalation rates and 210Pb deposition rates were performed over complete seasonal cycles, August 2002 - July 2003 and May 2003 - May 2004 respectively. The area is categorised as wet and dry tropics and it experiences two distinct seasonal patterns, a dry season (May-October) with little or no precipitation events and a wet season (December-March) with almost daily precipitation and monsoonal troughs. November and April are regarded as transitional months. As the natural processes of 222Rn exhalation and 210Pb deposition are heavily influenced by soil moisture and precipitation respectively, seasonal variations in the exhalation and deposition rates were expected. It was observed that 222Rn exhalation rates decreased throughout the wet season when the increase in soil moisture retarded exhalation. Lead-210 deposition peaked throughout the wet season as precipitation is the major scavenging process of this isotope from the atmosphere. Radon-222 is influenced by other parameters such as 226Ra activity concentration and distribution, soil porosity and grain size. With the removal of the influence of soil moisture during the dry season it was possible to examine the effect of these other variables in a more comprehensive manner. This resulted in categorisation of geomorphic landscapes from which the 222Rn exhalation rate to 226Ra activity concentration ratios were similar during the dry season. These results can be extended to estimate dry season 222Rn exhalation rates from tropical locations from a measurement of 226Ra activity concentration. Through modelling the 210Pb budget on local and regional scales it was observed that there is a net loss of 210Pb from the region, the majority of which occurs during the dry season. This has been attributed to the fact that 210Pb attached to aerosols is transported great distance with the prevailing trade winds created by a Hadley Circulation cell predominant during the dry season (winter) months. By including the influence of factors such as water inundation and natural 210Pb redistribution in the soil wet season budgeting of 210Pb on local and regional scales gave very good results.
30
Panza, Fabien. "Développement de la spectrométrie gamma in situ pour la cartographie de site." Phd thesis, Université de Strasbourg, 2012. http://tel.archives-ouvertes.fr/tel-00975929.
Full textAbstract:
La spectrométrie gamma à haute résolution offre un outil d'analyse performant pour effectuer des mesurages environnementaux. Dans le cadre de la caractérisation radiologique d'un site (naturelle ou artificielle) ainsi que pour le démantèlement d'installations nucléaires, la cartographie des radionucléides est un atout important. Le principe consiste à déplacer un spectromètre HPGe sur le site à étudier et, à partir des données nucléaires et de positionnements, d'identifier, de localiser et de quantifier les radionucléides présents dans le sol. Le développement de cet outil fait suite à une intercomparaison où un exercice orienté intervention a montré les limites des outils actuels. Une partie de ce travail s'est portée sur la représentation cartographique des données nucléaires. La connaissance des paramètres d'un spectre in situ a permis la création d'un simulateur modélisant la réponse d'un spectromètre se déplaçant au-dessus d'un sol contaminé. Ce simulateur a lui-même permis de développer les algorithmes de cartographie et de les tester dans des situations extrêmes et non réalisables. Ainsi, ce travail ouvre sur la réalisation d'un prototype viable donnant en temps réel les informations nécessaires sur l'identité et la position possible des radionucléides. La recherche réalisée sur la déconvolution des données permet de rendre en post traitement une carte de l'activité du sol par radionucléide mais également une indication sur la profondeur de la source. Le prototype nommé OSCAR (Outil Spectrométrique de Cartographie de Radionucléides) a ainsi été testé sur des sites contaminés (Suisse et Japon) et les résultats obtenus sont en accord avec des mesures de référence.
31
Marshall, Timothy. "Radionuclide speciation during mineral reactions in the chemically disturbed zone around a geological disposal facility." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/radionuclide-speciation-during-mineral-reactions-in-the-chemically-disturbed-zone-around-a-geological-disposal-facility(cf5d42af-8efd-41bd-b147-799b27ecaa11).html.
Full textAbstract:
Geological disposal of radioactive wastes currently stored at Earth's surface is now the favoured management pathway for these materials. Typically, intermediate level wastes (ILW) are grouted and emplaced in a geological disposal facility (GDF) which will be backfilled, possibly with cementitious materials. Post-closure leaching of the cementitious materials in a GDF is expected to create hyperalkaline conditions in and around the repository, resulting in mineral alteration and crystallisation, both within the engineered barrier and host rock; creating a persistent chemically disturbed zone (CDZ). Iron derived from within the host rock as a result of alkaline breakdown of Fe-bearing silicate minerals (e.g. biotite, chlorite); corrosion products formed within the repository; or iron contained within the waste; will form secondary iron (oxyhydr)oxide minerals. The formation and re-crystallisation of these reactive mineral phases may sequester radionuclides through a host of processes: surface-mediated reduction to less soluble forms; adsorption onto, and/or incorporation into stable secondary or tertiary iron oxide phases. Therefore iron (oxyhydr)oxides will be key to the fate of radionuclides potentially released from within radioactive wastes disposed of in a GDF.In this study, the fate of U(VI) and Tc(VII) was considered during crystallisation of ferrihydrite to more stable iron oxide phases (e.g. hematite and magnetite) and, in three synthetic cement leachates (pH 13.1, 12.5, 10.5) designed to reflect the early-, middle- and late-stage evolution of the CDZ. XRD and SEM/TEM have been used to characterise the mineralogy during crystallisation. Partitioning of U(VI) and Tc(VII) between the solid and solution has been followed throughout, with chemical extractions used to determine the distribution of the radionuclides adsorbed to, and incorporated within the solid. Synchrotron-based XAS techniques have been utilised to probe the oxidation state and molecular scale bonding environment of the radionuclides associated with the solids. The data suggest that: U(VI) is incorporated into the hematite structure in place of Fe(III), in a distorted octahedral environment with elongation of the uranyl bond; Tc(VII) is reduced to Tc(IV) and incorporated into the octahedral site within the magnetite structure in place of Fe(III), and is retained in the same environment even after extensive oxidation of the magnetite to maghemite; and that U(VI) may also be incorporated as U(V) or U(VI) into the magnetite structure, with similar recalcitrant behaviour during oxidation. These results highlight the importance of mineral reactions within the CDZ as potentially significant pathways for immobilising radionuclides released from a GDF.
32
Raddadi, Mohamed Chaker. "Etude de la nature de la radioactivité gamma dans les roches carbonatées de plate-forme : analyses et interprétations environnementales, diagénétiques et géodynamiques." Phd thesis, Université Joseph Fourier (Grenoble), 2004. http://tel.archives-ouvertes.fr/tel-00704890.
Full textAbstract:
Lors de l'interprétation des diagraphies de radioactivité des carbonates, les pics de gamma-ray sont très souvent assimilés à des pics d'argilosité. Les faibles radioactivités sont, quant à elles, attribuées à des niveaux calcaires très peu marneux et pauvres en matière organique. Toutefois, l'enregistrement de la radioactivité gamma totale à l'aide d'un scintillomètre portable dans les carbonates de la plate-forme urgonienne des environs de Grenoble a révélé l'existence d'anomalies de la radioactivité dans ces roches, notamment la présence de pics importants de la radioactivité dans des niveaux calcaires purs ou très pauvres en minéraux argileux et détritiques. Le but de ce travail a été d'arriver à identifier les éléments radioactifs associés aux différents types de carbonates, leurs localisations, leurs abondances et leurs contributions respectives au signal gamma total enregistré pour mieux comprendre l'origine de la radioactivité dans ces roches, d'une part, et proposer une méthode pour mieux utiliser l'outil gamma-ray pour des interprétations séquentielles et environnementales dans les séries de carbonates de plate-forme, d'autre part. Pour mener à bien ce travail nous avons choisi plusieurs sites d'études, mais nous nous sommes intéressés à deux intervalles bien particuliers : ~ le premier correspond à la séquence de dépôt BA3 (troisième séquence de dépôt du Barrémien supérieur) formée principalement de faciès calcaires. Nous avons étudié cette séquence dans les massifs subalpins septentrionaux des environs de Grenoble et dans le Jura suisse de la région de Neuchâtel, ~ le deuxième correspond à l'intervalle des couches inférieures à orbitolines. Nous avons étudié cet intervalle dans les massifs subalpins septentrionaux aux environs de Grenoble, en Espagne dans le bassin d'Organya et au Jebel Jediri dans la région de Kairouan en Tunisie. Nous avons réalisé une étude sédimentologique et séquentielle très détaillée de l'ensemble des coupes étudiées. L'analyse des isotopes stables du carbone et de l'oxygène nous a permis d'avoir une meilleure idée sur l'histoire et l'évolution diagénétique de ces carbonates, mais aussi de proposer une corrélation à grande échelle entre les différentes zones d'études. La corrélation des courbes isotopiques (& l3 C et &18 O) de l'intervalle des couches inférieures à orbitolines des massifs subalpins septentrionaux et de ses équivalents en Tunisie et en Espagne avec la coupe stratotypique du Bédoulien nous a permis d'apporter un argument de plus pour dater du Bédoulien inférieur cet intervalle des couches inférieures à orbitolines (CIO). Les analyses en spectrométrie gamma d'échantillons prélevés dans les différents faciès carbonatés étudiés, montrent clairement que c'est l'uranium qui est la principale source des émissions gamma dans ces roches et que les variations de la courbe gamma-ray totale est très étroitement liée aux variations des teneurs et de l'activité de cet élément. Des analyses complémentaires en lCP-MS nous ont permis de préciser qu'il existe au moins trois sources de l'uranium dans les carbonates de plate-forme: -l'uranium fixé dans les tests d'échinodermes qui abondent lors des phases d'approfondissement relatif des milieux de dépôt (aux environs des mfs et mfs relatives de paraséquences), -l'uranium qui provient de la circulation des fluides météoriques lors des phases d'émersion et qui se concentre dans les environs des limites de séquences de dépôt et de certaines paraséquences émersives. Nous avons réussi à montrer avec l'ensemble de ces analyses et observations que le gamma-ray ne peut pas être utilisé sans discussion critique comme outil de corrélation lithologique et que son utilisation indépendamment des autres outils diagraphiques peut conduire à corréler des ensembles sédimentaires très différents. *
33
Kleinschmidt, Ross Ivan. "Radioactive residues associated with water treatment, use and disposal in Australia." Thesis, Queensland University of Technology, 2011. https://eprints.qut.edu.au/48058/1/Ross_Kleinschmidt_Thesis.pdf.
Full textAbstract:
Water resources are known to contain radioactive materials, either from natural or anthropogenic sources. Treatment, including wastewater treatment, of water for drinking, domestic, agricultural and industrial purposes has the potential to concentrate radioactive materials. Inevitably concentrated radioactive material is discharged to the environment as a waste product, reused for soil conditioning, or perhaps recycled as a new potable water supply. This thesis, presented as a collection of peer reviewed scientific papers, explores a number of water / wastewater treatment applications, and the subsequent nature and potential impact of radioactive residues associated with water exploitation processes. The thesis draws together research outcomes for sites predominantly throughout Queensland, Australia, where it is recognised that there is a paucity of published data on the subject. This thesis contributes to current knowledge on the monitoring, assessment and potential for radiation exposure from radioactive residues associated with the water industry.
34
Amutkan, Ozge. "Space Radiation Environment And Radiation Hardness Assurance Tests Of Electronic Components To Be Used In Space Missions." Phd thesis, METU, 2010. http://etd.lib.metu.edu.tr/upload/12612238/index.pdf.
Full textAbstract:
Space radiation is significantly harmful to electronic Components. The operating time, duration and orbit of the space mission are affected by the characteristic of the radiation environment. The aging and the performance of the electronic components are modified by radiation. The performance of the space systems such as electronic units, sensors, power and power subsystem units, batteries, payload equipments, communication units, remote sensing instruments, data handling units, externally located units,
and propulsion subsystem units is determined by the properly functioning of various electronic systems. Such systems are highly sensitive against space radiation.
The space radiation can cause damage to electronic components or functional failure on the electronics. A precisely methodology is needed to ensure that space radiation is not a threat on the functionality and performance of the electronics during their operational lives. This methodology is called as &rdquoRadiation Hardness Assurance&rdquo
. In this thesis, the hardening of electronics against space radiation is discussed. This thesis describes the space radiation environments, physical mechanisms, effects of space radiation, models of the space radiation environment, simulation of the Total Ionizing Dose, and &rdquo
Radiation Hardness Assurance&rdquo
which covers Total Ionizing Dose and Single Event Effects testing and analyzing of the electronics.
35
Amaral, Paulo Giovany Quadros do. "Avaliação da alterabilidade e da exalação do gás radônio em rochas ornamentais." Universidade de São Paulo, 2016. http://www.teses.usp.br/teses/disponiveis/102/102131/tde-23012017-093147/.
Full textAbstract:
A presente tese se baseia no estudo das rochas ornamentais e de revestimento em relação aos seus aspectos de alterabilidade que irá influenciar diretamente no aumento da adição do gás radioativo radônio no interior de um ambiente com o passar do tempo de uso, fato devido as interações com o meio de onde é instalado a rocha, como exemplo da sua manutenção e limpeza, que implicará no seu padrão estético e na qualidade do ar do ambiente interior. Temas como a qualidade do ar interior relacionado a qualidade de vida do usuário, a radioatividade natural, o perigo do gás radiotivo radônio no interior do ambiente e as rochas ornamentais como composição e uso na arquitetura são apresentados para embasamento da Tese e auxiliando no entendimento dos ensaios realizados. Para isso, cinco rochas ornamentais foram escolhidas e realizados ensaios de alterabilidade química, ensaios tecnológicos de caraterização e ensaios de caracterização radiométrica a fim de prever o comportamento de uma dada rocha em seu ambiente ao ser aplicado na arquitetura. O ataque do ácido HCl nas rochas diminuiu sua resistência e aumentou a quantidade de radônio exalado relacionado diretamente ao aumento direto na porosidade, aumentando também a eficiência de exalação da rocha. O ataque do álcali KOH apesar de diminuir a resistência da rocha, interferiu na porosidade e diminuindo assim a quantidade de radônio exalado em alguns casos. Isso demonstra que mesmo conhecendo o material e a sua contribuição na adição do Rn no interior do ambiente, com o passar do tempo a rocha irá aumentar sua exalação quando não conservadas podendo aumentar o nível de radônio acumulado no ambiente. Com isso, a tese realça a importância de conhecer o material que irá compor o interior do ambiente afim de prevenir futuros danos à saúde da edificação e dos usuários, facilitando assim o entendimento desses materiais e como interfere na qualidade do ambiente construído.This thesis is based on the study of dimension stone in relation to aspects of changeability which will directly influence the increased addition of radon radioactive gas within an environment over time of use, a fact due to interactions with the environment where it is installed rock, as an example of its maintenance and cleaning, which will result in its aesthetic standard and quality of indoor air environment. Topics such as the quality of the related indoor air to the user\'s quality of life, natural radioactivity, the danger of radiotivo radon gas into the atmosphere and dimension stone as composition and use in architecture are presented to foundation this Thesis and aiding in the understanding of tests. For this, five ornamental stones were chosen and performed chemical tests changeability, technological characterization of assays and radiometric characterization tests to predict the behavior of a given rock in your environment to be applied in architecture. The attack of the HCl acid in the rocks decreased its strength and increased the amount of exhaled radon related directly to the direct increase in porosity, also increasing exhalation efficiency of the rock. The attack KOH alkali spite of reducing the resistance of the rock, and interfere with the porosity thereby decreasing the amount of radon vented in some cases. This shows that even knowing the material and its contribution to the addition of Rn into the environment, with the passage of time the rock will increase your exhalation when not maintained can increase the level of accumulated radon in the environment. Thus, the thesis highlights the importance of knowing the material that will form the inside of the environment in order to prevent further damage to the health of the building and users, thus facilitating the understanding of these materials and how it interferes in the quality of the built environment.
36
Sohl, Lukas. "Development of PICOSEC-Micromegas for fast timing in high rate environments." Thesis, université Paris-Saclay, 2020. http://www.theses.fr/2020UPASP084.
Full textAbstract:
Les futures expériences de physique des particules devront être opérationnelles pour un flux de particules et une luminosité croissants. Plus particulièrement, les détecteurs proches du point d'interaction devront présenter une très bonne robustesse pour faire face à un flux de particules très élevé. De plus, une résolution temporelle de quelques dizaines de picosecondes pour les particules au minimum d’ionisation sera nécessaire pour assurer une séparation nette des vertex reconstruits et réduire l'empilement d’événements. Ce manuscrit a pour sujet l’instrument PICOSEC-Micromegas, un détecteur de particules innovant basé sur la lecture d’un détecteur Micromegas couplé à un radiateur Cherenkov et une photocathode. Dans ce dispositif, chaque électron primaire étant produit à la surface de la photocathode, l’étalement en temps du signal est minimal, alors qu’il peut atteindre plusieurs nanosecondes lorsque les ionisations primaires ont lieu sur le passage d'une particule dans l’espace de dérive. La hauteur de ce dernier est ici du même ordre de grandeur que celle de la région d'amplification (100-200 μm) afin de minimiser l'ionisation directe du gaz. L’espace de dérive est également utilisée comme espace de pré-amplification. Un modèle mathématique, basé sur des simulations GARFIELD++, a été développé pour décrire le développement de l'avalanche de pré-amplification. Il a permis de montrer que la longueur et la multiplication de l'avalanche dans l’espace de dérive sont les facteurs dominants dans la résolution temporelle. Le concept PICOSEC-Micromegas a été étudié avec plusieurs prototypes optimisant les champs électriques, la distance de dérive et le mélange gazeux auprès de l’installation laser du LIDYL (Laboratoire Interactions, Dynamiques et Lasers). Une résolution temporelle de ~44 ps a été obtenue pour un photo‑électron unique. Par ailleurs, des mesures effectuées en faisceau test au CERN ont permis d'obtenir une résolution temporelle de 24 ps pour des muons de 150 GeV, avec un espace de dérive de 200 μm et une photocathode en CsI (10 photoélectrons par MIP). Afin de passer du concept de détection à un démonstrateur plusieurs prototypes ont été développés, en se concentrant sur les propriétés spécifiques nécessaires aux applications futures: segmentation de l'anode, annulation des étincelles, efficacité de la photocathode et robustesse à haut flux de particules. Un prototype à pads hexagonaux a été testé en faisceau et montré une résolution temporelle de ~36 ps dans le pad central. Les performances à haut flux sont testées avec des détecteurs résistifs dans des faisceaux de muons et de pions. Des résolutions temporelles nettement inférieures à 100 ps et un fonctionnement stable en faisceau de pions sont obtenus avec tous les prototypes résistifs. Des matériaux de photocathode robustes, comme alternative au CsI, sont étudiés pour réduire la dégradation due au retour des ions. Les matériaux les plus prometteurs sont le “diamond-like carbon” (DLC) et le carbure de bore (B4C). Compte tenu des résultats obtenus, deux cas d'application sont considérés pour les perspectives de ce programme de R&D. La première application considérée est l'utilisation du détecteur PICOSEC à l'intérieur d'un calorimètre comme couche de synchronisation ou de nombreuses particules secondaires sont produites dans un calorimètre électromagnétique après quelques longueurs de radiation. Une résolution temporelle de ~5 ps est attendue avec le PICOSEC-Micromegas. La seconde application est l'identification des particules par des mesures de temps de vol (TOF) ou PICOSEC-Micromegas devrait permettre de doubler la plage d’impulsion des détecteurs TOF actuels pour la séparation π/Κ avec 3σFuture particle physics experiments will face an increasing particle flux with rising beam luminosity. Detectors close to the interaction point will need to provide robustness against the high particle flux. Moreover, a time resolution of tens of picosecond for Minimum Ionising Particles will be necessary to ensure a clear vertex separation of the reconstructed secondary particles and to reduce pile-up. This manuscript focusses on the PICOSEC-Micromegas, an innovative particle detector based on the Micromegas readout coupled to a Cherenkov radiator and a photocathode in front of the gaseous volume. In this way, each primary electron is located on the surface of the photocathode, suppressing thus the inevitable time jitter of several nanoseconds, due to the different ionisation positions created by the passage of a particle from the drift region of a gaseous detector. The drift region length is reduced to the same order of magnitude as the amplification region (100-200 μm) to minimise direct gas ionisation, and it is additionally used as a pre-amplification stage. A mathematical model, based on GARFIELD++ simulations, is developed to describe the propagation of the pre-amplification avalanche showing that the length and multiplication of the avalanche in the drift region is the dominant factor in the timing performance. The PICOSEC-Micromegas concept is studied with several prototypes optimising the electric fields, the drift distance, and the gas mixture in the LIDYL (Laboratoire Interactions, Dynamiques et Lasers) UV laser facility. A single photoelectron time resolution of ~44 ps is measured with the shortest tested drift region length of 119,μm and the highest stable field setting. Measurements performed in the secondary particle beam at CERN have resulted in a time resolution of 24 ps for 150 GeV muons with a drift region length of 200 μm and a CsI photocathode providing 10 photoelectrons per MIP. In order to evolve from the detection concept to a versatile instrument, several prototypes are developed, focusing on specific properties needed for future applications: anode segmentation, spark quenching, photocathode efficiency and robustness for higher particle flux. An hexagonal segmented multipad prototype is tested in the beam with a time resolution of ~36 ps in the central pad. The operation in high rate environments is studied with different resistive strip and floating strip anodes resistive detectors in muon and pion beams. Time resolutions significantly under 100 ps and stable operation in the pion beam are achieved with all resistive prototypes. Robust photocathode materials, as an alternative to CsI, are investigated to reduce degradation from the ion-backflow generated in the pre-amplification avalanche. The most promising materials are diamond-like carbon (DLC) and boron carbide (B4C). Considering all the results achieved, two application cases are projected with the PICOSEC-Micromegas detector. The first one is the use in a calorimeter as a timing layer. Many secondary particles are produced in an electromagnetic calorimeter after few radiation lengths and a time resolution down to ~5 ps is expected with the PICOSEC-Micromegas. The second one is particle identification trough time-of-flight (TOF) measurements. The PICOSEC-Micromegas is expected to double the momentum range of current TOF detectors for π/Κ separation with 3σ
37
Merlin, Jérémie. "Study of long-term sustained operation of gaseous detectors for the high rate environment in CMS." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAE005/document.
Full textAbstract:
Le spectromètre à muons de CMS doit permettre l'identification rapide et efficace des muons produits lors des collisions proton-proton au LHC. Cependant, à cause d'un environnement de détection extrême, seules les chambres à pistes cathodiques équipent actuellement les bouchons de CMS. Cette faiblesse dans le système de détection pourrait devenir problématique après l'amélioration du LHC. L'augmentation du taux de particules dans les bouchons va dégrader les performances du système de déclenchement L1 ainsi que l'efficacité de sélection des phénomènes physiques intéressants. Le but du programme d'amélioration de CMS est de maintenir le taux de déclenchement L1 tout en gardant une efficacité de sélection maximale. La collaboration CMS GEM propose d'équiper les régions vacantes des bouchons avec des détecteurs basés sur la technologie d'amplification des électrons dans un gaz (GEM), appelés GE1/1. Le sujet de thèse proposé par la collaboration CMS GEM a pour but de justifier le choix de la technologie GEM pour l'amélioration de CMS. Trois projets ont été suivis pendant la thèse. La première partie du projet de thèse consistait à mesurer précisément les caractéristiques fondamentales et les performances de détection des détecteurs triple-GEM produit par la technique simple-masque. Ces éléments sont essentiels pour s'assurer que les détecteurs GE1/1 pourront fonctionner en toute sécurité dans l'environnement des bouchons de CMS. Le deuxième projet consistait à prouver que les excellentes performances des détecteurs GE1/1 ne vont pas se dégrader pendant leur utilisation dans CMS. Cette étape comprend l'étude du fonctionnement à long terme des détecteurs GE1/1, en particulier le phénomène de vieillissement, qui inclue tous les processus physiques et chimiques qui provoquent la dégradation graduelle et permanente des performances de détection. Plusieurs tests de vieillissement ont été menés dans des zones d'irradiations spécifiques au CERN pour reproduire un minimum de 10 ans de fonctionnement réel dans l'environnement de CMS après la montée en puissance du LHC. Enfin, les excellentes propriétés mesurées lors de la phase de R&D ont permis de valider la technologie triple-GEM, qui fut ensuite approuvée par la collaboration CMS et le comité du LHC. La production de 144 grands détecteurs GE1/1 sera partagée entre différents sites de production à travers le monde. Le troisième projet de thèse fut donc le développement des principales étapes du contrôle qualité nécessaire pour assurer une production uniforme et une même qualité pour tous les détecteurs GE1/1The muon system of CMS aims to provide an efficient and fast identification of the muons produced in the proton-proton collisions. However, the forward region of the end-caps is only instrumented with Cathode Strip Chambers. This lack of redundancy will be problematic after the high-luminosity upgrade of the LHC (HL-LHC), for which the increase of the background rate would degrade the Level-1 trigger performance and thus the selection of interesting physics channels. The goal of the CMS muon upgrade is to maintain the L1 trigger rate with maximum selection efficiency in order to fully exploit the HL-LHC. The CMS GEM Collaboration has proposed to instrument the vacant highetaregion of the muon end-caps with Gas Electron Multiplier (GEM) detectors, called GE1/1chambers.The Ph.D. subject proposed by the CMS GEM Collaboration aims to demonstrate that the GE1/1technology is the most suitable choice for the upgrade of the muon end-caps. Three main researchprojects were conducted in this context. The first project included the precise measurement of the fundamental characteristics and the detection performance of the triple-GEM detectors produced with the single-mask technique. Those characteristics are essential to ensure that the detectors can operate in the forward region of CMS. The second project was focused on the long-term operation of GE1/1 detectors, in particular the study of the aging phenomenon, which includes all the processes that lead to a significant and permanent degradation of the performance of the detectors. Several aging tests were performed at the CERN irradiation facilities to prove that the GE1/1 chambers can operate during at least 10 yearsat HL-LHC without suffering from performance losses. The excellent properties measured during the R&D phase led to the approval of the GE1/1 project by the CMS Collaboration. The third project, conducted in the framework of the mass production,consisted of developing of the main steps of the Quality Control of the GE1/1 chambers
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Lalucaa, Valérian. "Etude des effets singuliers produits par les particules énergétiques chargées de l’environnement radiatif spatial sur les capteurs d’images CMOS." Thesis, Toulouse, ISAE, 2013. http://www.theses.fr/2013ESAE0042/document.
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Ce mémoire de thèse traite des effets singuliers produits par les milieux radiatifs sur les capteurs d’images CMOS. Le travail se concentre sur les effets provoqués par les ions lourds sur les capteurs utilisant des pixels 3T à photodiode standard et des pixels 4T et 5T à photodiodes pincées. Dans un premier temps, l’étude se concentre sur l’environnement spatial et l’architecture des capteurs. La comparaison avec la littérature met en évidence les effets les plus critiques sur les capteurs : le SEL et les SET. Les capteurs testés expérimentalement valident les travaux théoriques. Les SET sont comparés aux simulations de l’outil de modélisation STARDUST, et montrent un bon accord pour toutes les puces et les ions. Il est expliqué pourquoi les SET sur les puces 3T sont insensibles aux variations de conception de la photodiode, et pourquoi l’utilisation d’un substrat épitaxié diminue grandement les SET. Une méthode de réduction des SET est implémentée avec succès sur les puces 4T et 5T, et le composant responsable du latchup est identifié. L’ensemble des mécanismes explorés permet de connaitre les paramètres importants pour durcir les imageursThis thesis studies the single event effects of space environment in CMOS image sensors (CIS). This work focuses on the effects of heavy ions on 3T standard photodiode pixels, and 4T and 5T pinned photodiode pixels. The first part describes the space radioactive environment and the sensor architecture. The most harmful events (SEL and SETs) are identified thanks to the scientific literature. The experimentally tested sensors agree with the theoretical work. SETs are compared to STARDUST simulations with a good agreement for all ions and sensors. The work explains why the SETs on 3T pixels are insensitive to the various photodiode designs, and they are decreased when an epitaxial substrate is used. A method using anti-blooming was successfully used in 4T and 5T pixels to prevent the spread of the SETs. The mechanism of latchup in 4T pixel sensors is described. All the identified mechanisms are very useful to provide hardening methods for the CISs
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Anandaram, B. N. "Study of environmental radioactivity in and around Shimoga." Thesis, 1998. http://hdl.handle.net/2009/1458.
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Sheng, Lin Shih, and 林時聖. "The Radioactivity Detection Of The Environmental Samples And Contruction Materials." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/30689549364335478536.
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Wu, Chien-Chung, and 吳建忠. "A Study on the Measurement of Environmental Radioactivity As a New Teaching Material for Environmental Science." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/87551882859881423514.
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碩士國立臺灣師範大學
化學研究所
87
Concerning the environmental radioactivity education, a survey was carried out by means of questionnaires for 1,160 students from 16 to 19 ages. Answers of students expressed, the majority of students has somewhat negative images for environmental radioactivity because they has obtained the information about radioactivity through the mass communication rather than learning in school. A new teaching materials for learning environmental radioactivity by means of G-M counter has been developed through measurement of K-40 in tobacco ash, vegetables, fruits and air-borne particlates. From several trial and error, it was found that measurement of air-borne particulates radioactivity deposited on the surface of the teflon plate was suitable for secondary school. Teaching the concepts of permissible or acceptable level of radioactivity was included.
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Tsai, Cheng-Che, and 蔡政哲. "Study on the Environmental Radioactivity of Gaseous Phases Around the Nuclear Power Plants in Northern Taiwan." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/25749518504329374656.
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碩士國立陽明大學
環境衛生研究所
91
Abstract It was a long-term serial research for the air quality and fallout amount in the community surrounding the nuclear power plant（Ⅰ）&（Ⅱ）in northern Taiwan, including Shihmen, Chinshan and Wanli. The purpose of this study was to analyze the change of radionuclides types and radioactivity concentration in these places in different time. We focused on the field of environmental air and fallout samples collection and radionuclides supervision. Since July 2001 to March 2002, there were eight sampling stations built on Shihmen, Maolin, Tsaoli, Chienhua, Chinshan, Chiatou, Wanli and Kanchiao, respectively around the two nuclear power plants. Regarding to this, 119 effective air samples obtained from seven stations in which the sampling were proceeded simultaneously and 4 effective air samples from Kungliao and the National Yang-Ming University on which the background sampling stations were located. In total 123 air samples, radionuclides Be-7 and K-40 were found. The radioactivity concentration of Be-7 was shown lower than the detection limit of ~11.9 mBq/m3 and that of K-40 also below the detection limit of ~7.5 mBq/m3. The radionuclides of the series of natural Uranium (Bi-214, Pb-214) and Thorium (Tl-208, Pb-212, Bi-212) were obtained from 53 samples. The range of the radioactivity concentration is from the detection limit to 0.9 mBq/m3. However, the radioactivity concentration of the artificial radionuclides in the 123 samples were shown lower than the detection limit of apparatus. Moreover, the samples of superficial dust were collected since October 2001 to May 2002. Night successful samples were collected at the roof of the buildings in the residential area, including Chinshan, Shihmen, and the background area, Kanchiao, National Yang-Ming University. It had been found that there were artificial radionuclides, Mn-54（0.4±0.1~0.5±0.1Bq/kg-dry）, Co-60（0.4±0.1~1.4±0.1Bq/kg-dry）, Cs-137（3.7±0.2~10.0±0.5Bq/kg-dry）, in the samples of Shihmen on 2 October 2001; Cs-137（2.9±0.3~4.1±0.5Bq/kg-dry, 2.5±0.5~3.7±0.4Bq/kg-dry）in the samples of Chinshan were also found on 11 April 2002 and 7 May 2002. Besides, it had been found that there were artificial radionuclides of lower than 0.105 mm fine particles, Mn-54（0.6±0.1~0.7±0.2Bq/kg-dry）, Co-60（0.9±0.2~2.1±0.3Bq/kg-dry）, Cs-137（2.7±0.3~5.6±0.7Bq/kg-dry）, in the samples of Shihmen on 26 February 2002; Co-60（1.6±0.3~2.9±0.4Bq/Kg-dry）and Cs-137（2.6±0.3~5.8±0.7Bq/kg-dry）in the samples of Shihmen were also found on 2 April 2002 and 7 May 2002. But we did not find artificial radionuclides in the samples from the background area. The resource of this artificial radionuclides made it possible to be affected by the accumulation of the fallout emitted by the nearby nuclear power plant. A further research is worthy of clarifying and understanding the distribution of environmental radionuclides in order to confirm the influence of the two power plants on the local environment.
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Silva, Fábio Alberto Borges Nunes da. "Effects of radioactivity and other variables on aquatic microorganisms: case study in springwaters in Auvergne." Master's thesis, 2021. http://hdl.handle.net/10773/32576.
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The present work proposes to show the most recent information regarding the microorganisms present in mineral and thermal springs, talking about the influence that different environmental variables, with a focus on radioactivity, have on the prokaryote and virus communities. The dissertation consists of Part 1, which is a literature review that addresses prokaryotes and viruses in water sources. The review addresses the impact of variables such as temperature, pH and radioactivity on both groups, both in the freshwater context in general and specifically in water sources. Then, in Part 2, what was done in the practical work is discussed, which consists of the treatment of flow cytometry data from various water sources in the Auverge region, France. The practical work consisted of a three-month Erasmus+ internship at the LMGE, Université Clermont-Auvergne, France. An analysis of biotic and abiotic parameters was then carried out in various water sources in the volcanic area of the Massif Central, Auvergne region. Statistical analysis of flow cytometry data was performed using Excel and XLSTAT and with the aim of analyzing the interaction between the various variables in the studied sources. For this, a PCA was performed for all variables and all sources, along with a dendrogram for analysis of similarity/dissimilarity between sources. The PCA results allowed us to make some observations: a strong positive correlation between the concentration of prokaryotes and gamma radiation and conductivity, but a negative correlation between these variables and the concentration of radon; virus concentration had a weak correlation with both prokaryote concentration and gamma radiation, and a negative correlation with radon activity. The negative correlation between radon and gamma radiation, together with the strong correlation between gamma radiation and prokaryotes, were the observations that drew the most attention and the current understanding of the interactions between these variables is still poor. No literature was found that explained these two observations. For the negative correlation between radon and gamma radiation, it is known that radon activity is characterized by the release of alpha radiation, while gamma radiation is released by radon daughters such as 214Pb. Therefore, in my hypothesis, the amount of gamma radiation would be directly correlated with the quantity of these daughters that form from radon decay. The results of the dendrogram allowed to observe three separations of sources in terms of dissimilarity. There was a font with greater dissimilarity, Par, and two other font groups. The isolation of the Par source is due to the fact that it is by a good margin the hottest source, with 78ºC. Another group of sources is separated mainly by the action of the radon concentration variable, while the other is separated by the action of other variables such as gamma radiation and conductivity. Research about the influence of radioactivity in microorganisms in freshwater and springwater is still a subject of limited interest, and research is lacking. Also, the results mentioned are still preliminary and limited by the action of COVID. Still, this offers a start in terms of future research, namely on the impacts of radioactivity on different groups of microorganisms in water sources. Still, this offers a starting point in terms of future research, namely on the impacts of radioactivity on different groups of microorganisms in water sources. Future studies are needed that include analysis of prokaryotic and viral communities (species and strains), which will allow to obtain a full perspective of the influence of radioactivity on these microorganisms.O presente trabalho propõe-se a mostrar as informações mais recentes a respeito dos microrganismos presentes em fontes minerais e termais, falando sobre a influência que diferentes variáveis ambientais, com foco na radioatividade, têm nas comunidades procariotas e virais. A dissertação consiste na Parte 1, que é uma revisão da literatura que aborda procariotas e vírus em fontes de água. A revisão aborda o impacto de variáveis como temperatura, pH e radioatividade em ambos os grupos, tanto no contexto de água doce em geral quanto especificamente nas fontes de água. Em seguida, na Parte 2, é discutido o que foi feito no trabalho prático, que consiste no tratamento de dados de citometria de fluxo de várias fontes de água na região de Auverge, França. O trabalho prático consistiu em um estágio Erasmus + de três meses na LMGE, Université Clermont-Auvergne, França. Uma análise dos parâmetros bióticos e abióticos foi então realizada em várias fontes de água na área vulcânica do Maciço Central, região de Auvergne. A análise estatística dos dados da citometria de fluxo foi realizada no Excel e XLSTAT e com o objetivo de analisar a interação entre as diversas variáveis nas fontes estudadas. Para isso, foi realizada uma PCA para todas as variáveis e todas as fontes, juntamente com um dendrograma para análise de similaridade / dissimilaridade entre as fontes. Os resultados da PCA permitiram fazer algumas observações: uma forte correlação positiva entre a concentração de procariotas e a radiação gama e condutividade, mas uma correlação negativa entre essas variáveis e a concentração de radon; a concentração do vírus teve uma correlação fraca com a concentração de procariotas e radiação gama, e uma correlação negativa com a atividade do radon. A correlação negativa entre radão e radiação gama, juntamente com a forte correlação entre radiação gama e procariotas, foram as observações que mais chamaram a atenção, e o entendimento atual das interações entre essas variáveis ainda é pobre. Não foi encontrada literatura que explicasse essas duas observações. Para a correlação negativa entre radão e radiação gama, sabe-se que a atividade do radon é caracterizada pela libertação de radiação alfa, que é libertada pelas filhas do radão, como o 214Pb. Portanto, pela minha hipótese, a quantidade de radiação gama seria diretamente correlacionada com a quantidade dessas filhas que se formam a partir do decaimento do radão. Os resultados do dendrograma permitiram observar três separações de fontes em termos de dissimilaridade. Havia uma fonte com maior dissimilaridade, Par, e dois outros grupos de fontes. O isolamento da fonte Par deve-se ao fato de ser por uma boa margem a fonte mais quente, com 78ºC. Outro grupo de fontes é separado principalmente pela ação da variável concentração de radon, enquanto o outro é separado pela ação de outras variáveis como radiação gama e condutividade. A pesquisa sobre a influência da radioatividade em microrganismos em água doce e nascente ainda é um assunto de interesse limitado, e há carência de pesquisa. Além disso, os resultados mencionados ainda são preliminares e limitados pela ação do COVID. Ainda assim, isto oferece um ponto de partida em termos de pesquisas futuras, nomeadamente sobre os impactos da radioatividade em diferentes grupos de microrganismos nas fontes de água. Futuros estudos são necessários e que incluam análise das comunidades procarióticas e virais (espécies e estirpes), o que permitirá obter uma perspectiva total da influência da radioatividade nestes microorganismos.
Mestrado em Microbiologia
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Qwasmeh, Ahmed Ali Husein [Verfasser]. "Environmental radioactivity in different climate types : measurement, terrestrial transport process and radiation exposure / von Ahmed Ali Husein Qwasmeh." 2008. http://d-nb.info/989825051/34.
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