The detonation of a radiological dispersal device (RDD) may result in casualties receiving exposure of radioactive materials. Assessments of potentially contaminated personnel are necessary to determine the level of contamination received in order to prioritize and treat individuals. The use of improvised explosive devices (IEDs) and the number of orphan sources in deployed and combat areas such as Iraq, present an opportunity for terrorists to use an RDD against deployed ground forces. There is limited capability in Iraq to assess radiological casualties, as the process of obtaining and analyzing bioassays is time consuming and not readily available in country. Military units are equipped with AN/VDR-2 and AN/PDR-77 radiac detectors which are capable of detecting gamma radiation. Therefore, a study of the use of these radiac sets in assessing internal contamination was conducted. A model of the detector probe was created using the Los Alamos National Laboratory Monte Carlo N-Particle transport code, MCNP Version 5. This model was experimentally validated and used in conjunction with both reference male and reference female computational Medical Internal Radiation Dose (MIRD) phantoms to compute internal dose. The instrument model was evaluated at the following locations, the posterior upper right torso, the anterior upper right torso, the lateral upper left thigh and the anterior of the neck. Nuclides were distributed throughout the phantoms using the Oak Ridge National Laboratory Dose and Risk Calculation (DCAL) software for inhalation pathways. Based on the likelihood for use in RDDs and the capabilities of the instrument, Co-60, Cs-137 and Ir-192 were evaluated.

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The Earth’s upper atmosphere is suffused by radiation caused primarily by a bombardment of Cosmic Rays, as a result of which it is hazardous for human beings as well as sensitive electronic equipment on board flight vehicles. A series of ground based as well as airborne experiments were performed using Polylactic Acid (PLA), Acrylonitrile-Butadiene-Styrene (ABS) and High Impact Polystyrene (HIPS), in order to investigate the applicability of polymers that can meet today’s needs for lightweight, multifunctional, and cost efficiency in radiation shielding of electronic equipment. It was found that PLA at 8 mm thickness has an effectiveness of 66% against gamma radiation (i.e., it blocked 66% of the gamma radiation). Therefore, it was decided to proceed with a high altitude balloon experiment with an 8 mm thickness of PLA. The shield was demonstrated to be reasonably effective in attenuating radiation from cosmic rays.

This thesis describes about theoretical design and practical realization of self-contained module for intensity and absorbed dose measuring of X-Radiation from High Voltage X-RAY industrial sources. In the first part, thesis is focused on ways and solutions of radiation protection and principles of measuring absorbed dose and intensity of radiation and possibilities of sending measured data through sensor networks. In the second part, the complete schematic of measuring module is solved, critical blocks are tested and design of PCB is done. Detection circuit, blocks for optical and acoustic signaling, power management and control of the entire device are designed. Detection circuit uses a GM Tube. Next, main box of whole device is designed and made by 3D printing technology. The next step is putting hardware into operation and writing test firmware included verification of wireless communication through WiFi.

This research investigates the use of G-M counters to triage the individuals who have been exposed to a Radiological Dispersal Device (RDD). Upon being exposed to an RDD, inhalation of the airborne radionuclide is a method which someone can receive a considerable amount of dose. Bioassay via analysis of excreta is a commonly used method of determining the dose received, yet it would be cumbersome if there are a large number of people needing to be screened. An in vivo method must be considered so that a non-intrusive and more efficient triaging method can be implemented. Whole body counters are commonly used in counting facilities as an in vivo bioassay method, yet they are limited in number and not easily portable. Therefore, a more portable and more common detection device should be considered. G-M survey meters are common devices that are highly portable, making them ideal candidates to fulfill this necessity. The ease of use contributes to the viability of the device as a portable, in vivo screening device. To analyze this detector, a Monte Carlo model of the detector was created to be used in simulations with the Medical Internal Radiation Dose phantoms. The detector was placed in a few locations on the phantoms. Four locations were strategically chosen for detector placement: the posterior upper right torso, the anterior upper right torso, the lateral upper thigh, and the anterior of the neck. Six phantoms were considered: Reference Male, Female, Adipose Male, Adipose Female, Post Menopausal Adipose Female, and a Child. Six radionuclides were investigated: Am-241, Co-60, Cs-137, I-131, Ir-192, and Sr-90. The nuclides were distributed throughout the phantoms according to Dose and Risk Calculation Software, a code that determines how a radionuclide is distributed over time upon inhalation, ingestion, or injection. A set of time dependent guidelines were developed, determining the count rate per unit dose inhaled for each detector location and phantom type.

L'imagerie laser 3D est une technique performante utilisée notamment pour cartographier l'environnement dans lequel évolue un aéronef, en mesurant la distance le séparant d'un objet, en plus des coordonnées (x,y). Le système est capable d'acquérir des mesures par tout temps (nuit, pluie, brouillard). Une nouvelle génération de capteurs, multi-pixels et ultra-sensibles, permet alors de répondre aux besoins identifiés pour cartographier avec précision une zone de grande superficie : haute résolution spatiale, longue portée avec précision centimétrique et rapidité d'acquisition. Il s'agit des plans focaux 3D Geiger. Avant leur utilisation en aéroporté, il était nécessaire de se familiariser avec leur fonctionnement, basé sur les probabilités de détection. Un simulateur reproduisant l'ensemble de la chaîne d'acquisition à été développé, puis validé sur des cas réels, au sol et en conditions statiques. Il a ensuite permis de démontrer l'intérêt des plans focaux Geiger pour la cartographie aéroportée à longue distance. / 3D laser imaging is a powerful technique used to recognize the environment around an aircraft, by measuring the distance between the system and an objet, in addition to its spatial coordinates. Also, it allows data acquisition under any weather condition (night, rain, fog). A new kind of sensors, multi-pixel arrays with high sensitivity, seems in line with the needs of an accurate 3D mapping of a big area : high spatial resolution, longe range detection with centimeter accuracy and low acquisition time. There are 3D Geiger-mode focal plane arrays. Before an onboard use, it was necessary to analyze the operation of such a sensor, based on probabilities of detection. An end-to-end simulator reproducing the entire acquisition process has been implemented, then experimentally validated on ground and static cases. It finally allowed to demonstrate the potential and contribution of Geiger-mode focal plane arrays for long distance and high spatial resolution airborne 3D mapping.

My family has always been a source of inspiration to me. In the following sections, I attempt to capture the unique experience of growing up as one of them: how they’ve shaped me as I have grown, and the marks we’ve left on one another. / Includes bibliography. / Thesis (M.F.A.)--Florida Atlantic University, 2017. / FAU Electronic Theses and Dissertations Collection

This thesis explores Single-Photon Avalanche Diodes (SPADs), which are solid-state devices for photon timing and counting, and concentrates on SPADs integrated in nano-scale CMOS. The thesis focuses on: the search for new theory regarding Geiger-mode operation; proving the utility of calibrated Technology Computer- Aided Design (TCAD) tools for accurately simulating SPADs for the first time; the investigation of how manufacture influences device operation; and the integration of high performance SPADs into CMOS which rival discrete devices. The accepted theories of SPAD operation are revisited and it is discovered that previously neglected minority carriers have many significant roles such as determining: after-pulsing, Dark Count Rate (DCR), bipolar “SPAD latch-up,” nonequilibrium DCR, and “quenching”. The “quenching” process is revisited and it is concluded that it is the “probability time” of ≈100-200ps, and not the previously thought latching current that is important. SPADs are also found to have transient negative differential resistance. The new theories of SPADs are also supported by steady-state 1D, 2D and 3D TCAD simulations as well as novel transient simulations and videos. It is demonstrated as possible to simulate DCR, Photon Detection Efficiency (PDE), guard ring performance, breakdown voltage, breakdown voltage variation, “quenching,” and transient operation of SPADs with great accuracy. The manufacture of SPADs is studied focusing on the operation and optimisation of guard rings and it is found that ion implantation induced asymmetry from the tilt and rotation/twist is critical. Where symmetric, guard rings fail first along the <100> directions due to enhanced mobility. Process integration rules are outlined for obtaining high performance SPADs in CMOS while maintaining compatibility with transistors. The minimisation of tunnelling with lightly-doped junctions and the reduction of ion implantation induced defects by additional annealing are found essential for achieving low DCR. The thesis demonstrates that it is possible to realise high performance SPADs in CMOS through the innovation of a “Deep SPAD” which achieves record PDE of ≈72% at 560nm with >40% PDE from 410-760nm, combined with 18Hz DCR, <60ps FWHM timing resolution, and <4% after-pulsing which is demonstrated to have potential for significant further improvement. The findings suggest that CMOS SPAD-based micro-systems could outperform existing photon timing and counting solutions in the future.

La genèse des travaux présentés dans ce mémoire se situe dans le domaine de l'astrophysique des très hautes énergies. Il y a un siècle les scientifiques de la planète ont identifié un nouveau type de messagers venant de l'espace : les rayons cosmiques. Ce rayonnement est constitué de particules (photons et autres) de très haute énergie qui bombardent la terre en permanence. Le passage de rayonnements cosmiques dans l'atmosphère terrestre se traduit par la génération de brefs éclairs lumineux (5ns) d'une intensité très faible (1pW) : le flash Tcherenkov, devenant alors visible du sol.<br /><br />Dans l'état de l'art le meilleur détecteur de lumière est aujourd'hui le Photomultiplicateur (PMT), grâce à ses caractéristiques de sensibilité et de vitesse. Mais il présente quelques inconvénients : faible efficacité quantique, coût, poids etc. Nous présentons dans cette thèse une nouvelle technologie alternative : les compteurs de photons sur semi-conducteur, constitués de photodiodes polarisées en mode Geiger.<br />Ce mode de fonctionnement permet d'obtenir un effet de multiplication au moins identique à celui des PMT. Un modèle physique et électrique a été développé pour reproduire le comportement de ce détecteur.<br />Nous présentons ensuite dans ce travail de thèse un procédé technologique original permettant la réalisation de ces dispositifs dans la centrale de technologie du LAAS-CNRS, avec la simulation de chaque opération du processus.<br />Nous avons mis au point une fiche pour la caractérisation électrique des dispositifs, du mode statique au mode dynamique, et vérifié la conformité aux simulations SILVACO, et au modèle initial. Les résultats obtenus sont déjà excellents, compte tenu qu'il s'agit d'une première étape de prototypage, et comparables avec les résultats publiés dans la littérature.<br />Ces composants sur silicium peuvent intervenir dans toutes les applications où il y a un photomultiplicateur, et le remplacer. Les applications sont donc très vastes et la croissance du marché très rapide. Nous présentons une première expérience d'astrophysique installée au Pic du Midi qui a détecté des flashs Tcherenkov de rayons cosmiques avec cette nouvelle technologie à semi-conducteur.