Добірка наукової літератури з теми "SoLi∂ detector"

Cette thèse présente la recherche d'oscillations d'antineutrinos actifs vers des antineutrinos stériles avec le détecteur SoLi∂. Ce détecteur promeut un concept innovant basé sur un sandwich de plastiques scintillant formé de polyvinyle-toluène composite et de scintillateurs 6LiF:ZnS(Ag). Trois contributions principales à cette recherche sont rapportées dans ce document. La première concerne une nouvelle méthode de reconstruction basée sur l'algorithme ML-EM. Elle vise à transformer la réponse brute du détecteur en une liste de positions (avec des énergies dédiées) où l'interaction physique réelle dans le détecteur a eu lieu. La seconde concerne l'étalonnage en énergie du détecteur. Elle comprend à la fois l'étalonnage relatif au moyen de muons cosmiques horizontaux et l'exploration de plusieurs options pour la détermination de l'échelle d'énergie absolue. Enfin, la thèse présente une nouvelle méthode de sélection des candidats antineutrinos basée sur l'analyse de la partie électromagnétique du signal de désintégration bêta inverse et leur classement en fonction de la géométrie des événements dans le détecteur (topologies). L'analyse a été développée en aveugle et la méthode a été validée avec une petite fraction de l'échantillon de données<br>This thesis presents the search for active-to-sterile antineutrino oscillations with the SoLi∂ detector, which has an innovative concept based on a sandwich of composite polyvinyl-toluene and 6LiF:ZnS(Ag) scintillators. Three main contributions to this search are reported. The first one describes the new reconstruction method based on the ML-EM algorithm. It is aimed at transformation of the raw detector response to the list of positions (with dedicated energies) where actual physics interaction in the detector took place. The second one describes the energy calibration of the detector. It includes both relative calibration with the cosmic horizontal muons and exploration of several options for the absolute energy scale derivation. Finally, the thesis presents a novel method for selecting antineutrino candidates based on the analysis of the electromagnetic part of the inverse beta decay signal and categorising them according to the geometry of the events in the detector (topologies). The analysis was developed blindly and the method was validated with a small fraction of the data sample

Orientadores: Jacobus Willibrordus Swart, Pierre Kaufmann<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação<br>Made available in DSpace on 2018-08-22T19:46:53Z (GMT). No. of bitstreams: 1 Fernandes_LuisOlavodeToledo_M.pdf: 8033391 bytes, checksum: 7b7a925bf8a485ca4f76b7c8380299b3 (MD5) Previous issue date: 2013<br>Resumo: O telescópio solar submilimétrico operando nas freqüências de 212 e 405 GHz detectou uma nova componente espectral das emissões de explosões solares, com máximo em algum ponto da faixa Terahertz, simultaneamente com a conhecida componente espectral em microondas, trazendo sérios desafios para interpretação. O diagnostico deste tipo de emissão transiente em freqüências THz traz desafios tecnológicos que são objetivo deste estudo. Este projeto consiste em um estudo das características de filtros e sensores não refrigerados para aplicação em projeto aeroespacial na faixa Terahertz do espectro eletromagnético. Foram estudados e caracterizados detectores bolométrico, piroeletrico, e optoacustico, precedidos por filtros passa-baixa que suprimem a radiação na faixa do visível e infravermelho próximo do espectro eletromagnético, filtros passa-banda centrados na freqüência THz desejada, e modulador mecânico. O detector a célula de Golay mostrou ser o mais sensível. Foi selecionado para o protótipo de fotômetro THz que serviu para definir parâmetros de projeto para o modelo de vôo, para observação solar fora da atmosfera terrestre, em balões estratosféricos, satélites, ou estações no solo com atmosfera excepcionalmente transparente. O sistema foi concebido para observar todo o disco solar e detectar pequenas variações relativas de temperatura causadas por explosões em regiões especifica do Sol. Obteve-se mínima detectabilidade de variações relativas de temperatura da ordem de 1 K com resolução temporal de subsegundo<br>Abstract: The solar submillimeter-wave telescope, operating at 212 and 405 GHz frequencies detected a new flare spectral component emission, peaking in the THz range, simultaneously with the well known microwaves component, bringing challenging constrains for interpretation. The diagnostics of this kind of transient emission at THz frequencies also bring technical challenges, which are the subject of this study. The project consists in a study of the characteristics of filters and uncooled detectors for aerospace project application at THz range of the electromagnetic spectrum. Three types of uncooled sensors were tested: bolometric, pyroelectric, and optoacoustic, proceeded by low-pass filters to suppress the visible and infrared radiation, band-pass filter centered at THz frequency, and a chopper. The Golay cell sensor was considered the most sensible detector of all, and was selected for the photometer prototype THz system to observe the Sun outside the terrestrial atmosphere on stratospheric balloons or satellites, or at exceptionally transparent ground stations. The system was designed to observe the whole solar disk detecting small relative changes in input temperature caused by flares at localized positions of the Sun. The minimum relative temperature variation detected was about 1 K with subsecond time resolution<br>Mestrado<br>Eletrônica, Microeletrônica e Optoeletrônica<br>Mestre em Engenharia Elétrica

The current and possible uses of semiconductor solid state detectors in nuclear physics are briefly discussed. The theory of solid state detectors is discussed with emphasis on the silicon PIN diode detector. A fabrication process for silicon surface barrier position sensitive solid state detectors has been developed at UBC based on the work of J.B.A. England. A fabrication process recipe is included. A prototype surface barrier detector system has been built and tested at UBC and TRIUMF using this process. The device has 1 mm position resolution in one direction, an active area of 40 mm in diameter and a mass thickness of 55 mg/cm². The measured efficiency for 50 MeV pions is 70% and expected rate capability is in excess if 1 MHz per strip. The detector efficiency is limited by a marginal signal-to-noise ratio.<br>Science, Faculty of<br>Physics and Astronomy, Department of<br>Graduate

Orientador: Elnatan Chagas Ferreira<br>Texto em inglês<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Elétrica e de Computação<br>Made available in DSpace on 2018-08-20T11:54:01Z (GMT). No. of bitstreams: 1 Dias_PedroCarvalhaes_M.pdf: 7362254 bytes, checksum: dd839cf652cbbda17a2a5d9b6cecbdc3 (MD5) Previous issue date: 2012<br>Resumo: A constante preocupação em aumentar a produtividade das plantações de uma forma sustentável e otimizando o uso dos insumos agrícolas (água, fertilizantes, pesticidas e produtos para correção do PH) levou ao desenvolvimento da agricultura de precisão, que permite determinar a quantidade correta de insumos para cada região do solo (tipicamente um hectare), evitando o desperdício. Sensores de umidade de solo de baixo custo e fácil aplicação no campo são fundamentais para permitir um controle preciso da atividade de irrigação, sendo que os sensores que melhor atendem estes requisitos são os chamados sensores de dissipação de calor ou sensores de transferência de calor. Estes sensores, entretanto, apresentam um problema de baixa sensibilidade na faixa de umidade mais importante para as plantas (umidade de solo 'teta'v variando entre 5% e 35%), pois, para cobrir esta variação de 30% em 'teta'v com resolução de 1%, é necessário medir variações de temperatura de aproximadamente 0,026 ºC nos sensores de pulso de calor a duas pontas e 0,05 ºC para os sensores de pulso de calor de ponta simples. Neste trabalho foi desenvolvido um novo sensor de umidade de solo do tipo pulso de calor de ponta simples, baseado em um único elemento: um transistor bipolar de junção npn, que é usado tanto como aquecedor e como sensor de temperatura de alta precisão. Resultados experimentais, obtidos em medidas realizadas através de uma técnica de interrogação especialmente desenvolvida para este novo sensor mostram que neste trabalho foi possível obter uma sensibilidade cerca de uma ordem de grandeza maior do que nos sensores de pulso de calor com uma ponta e cerca de 20 vezes maior do que nos sensores de pulso de calor de duas pontas. Outra vantagem da técnica desenvolvida é que o aumento da sensibilidade não é obtido às custas do aumento da corrente drenada da bateria para aquecer o sensor. No sensor desenvolvido é utilizada uma corrente de apenas 6 mA para gerar o aquecimento (com energia dissipada de 1,5 J), enquanto que que os sensores de pulso de calor com ponta simples requerem cerca de 50 mA (com 2,4 J de energia dissipada) para operar. Os sensores de pulso de calor de ponta dupla também são fabricados com resistores que requerem cerca de 50 mA para o aquecimento (0.8 J de energia dissipada) para operar corretamente<br>Abstract: The concern regarding sustainable development and crop inputs optimization (such as water, fertilizers, pesticides and soil PH correction products) has led to the development of the precision agriculture concept, that allows to determine the exact amount of each input required on each ground section (typically one hectare), avoiding waste of inputs. Low-cost and easily handled soil moisture sensors are very important for allowing a precise irrigation control. The class of sensors which fulfill those requirements are the heat transfer sensors, where there are basically two types of devices: dual (or multi) probe heat pulse sensors and single probe heat pulse sensors. However, these sensors have a low sensitivity in the most important range of soil humidity 'teta'v for plants (usually from 5% ? 'teta'v ? 35%). To cover this 30% soil humidity range with 1% resolution it is necessary to measure temperature with a resolution of 0,026 ºC in the dual/multi probe heat pulse sensors and 0,05 ºC in the single probe heat pulse sensor. In this work it was developed a new type of single probe heat pulse sensor, comprised of a single element: an npn junction bipolar transistor, that plays the role of both the heating element and a high accuracy temperature sensor. Experimental results, obtained through an interrogation technique especially developed for this sensor, show sensitivity about one order of magnitude greater than the typical sensitivity of the single probe heat pulse sensors and 20 times greater than dual probe heat pulse sensors. Another great advantage of the developed interrogation technique is that the increase in sensibility is not obtained through a higher current being drained from the batteries that power the sensor. The developed sensor operates at a much lower current level than the other sensors, draining only 6 mA from the battery (with an energy of 150 mW). The single probe heat pulse sensor requires 50 mA and 1.5 J of energy to operate, whilst the dual probe heat pulse sensors are manufactured with resistors which also drain 50 mA from the battery with 0.8 J of dissipated energy<br>Mestrado<br>Eletrônica, Microeletrônica e Optoeletrônica<br>Mestre em Engenharia Elétrica

In this work novel solid-state neutron detectors based on Gallium Nitride (GaN) have been produced and characterized. GaN is a radiation hard semiconductor which is commonly used in commercial optoelectronic devices. The important design consideration for producing GaN-based neutron detectors have been examined, and device simulations performed. Scintillators and p-i-n diode-type neutron detectors have been grown by metalorganic chemical vapor deposition (MOCVD) and characterized. GaN was found to be intrinsically neutron sensitive through the Nitrogen-14 (n, p) reaction. Neutron conversion layers which produce secondary ionizing radiation were also produced and evaluated. GaN scintillator response was found to scale highly linearly with nuclear reactor power, indicating that GaN-based detectors are suitable for use in the nuclear power industry. This work is the first demonstration of using GaN for neutron detection. This is a novel application for a mature semiconductor material. The results presented here provide a proof-of-concept for solid-state GaN-based neutron detectors which offer many potential advantages over the current state-of-the-art, including lower cost, lower power operation, and mechanical robustness. At present Helium-3 proportional counters are the preferred technology for neutron detection, however this isotope is extremely rare, and there is a global shortage. Meanwhile demand for neutron detectors from the nuclear power, particle physics, and homeland security sectors requires development of novel neutron detectors which are which are functional, cost-effective, and deployable.

The purpose of this research is to determine the feasibility of creating an affordable and durable neutron detector for usage in the field surveys, site inspections, and transportation hub monitoring. Currently, organic scintillating detectors are an established method of detecting neutrons but are either costly, fragile solids like stilbene, or flammable liquids like benzene. In this work, several scintillation mixtures were tested with a PuBe source, which emits both neutrons and gamma rays. The pulse shape discrimination method was utilized to separate the signal pulses created from the mixed radiation field of the PuBe source. Two candidate mixtures were selected for solidification with elastomers for their verified neutron detection capabilities. The solid detectors measured high energy neutrons and gamma rays from the PuBe source. The solidified detectors have a Figure of Merit for separating neutrons of 0.859 ±0.419 and cost $0.13 per gram, while commercially available stilbene separates neutrons from gammas with a Figure of Merit of 4.70 and costs $64.36 per gram. This research shows that it is feasible to create affordable solid organic scintillators sensitive to high energy neutrons.