The measurement of the distribution of kinetic energy carried by neutron particles is of interest to the health physics and radiation protection industry. Neutron particle spectral fluence is essential to the calculation of absorbed dose, equivalent dose, and other dosimetric quantities . Current methods of neutron spectrometry require either a large number of individual measurements and a priori spectral information, or complex and delicate equipment. To reduce these deficiencies, a novel neutron spectrometer, consisting of plastic scintillating fibers in a hexagonal array, was simulated via Monte Carlo. Fiber size and boron content were varied to optimize response characteristics. The results were compared to industry standard multi-sphere spectrometers. Of the geometries and materials analyzed, it was found that smaller diameter fibers with 1% loading of natural boron provide the best efficiency and energy resolution. Energy resolution was found to be similar to multi-sphere spectrometers, with the ability to differentiate on the order of ten energy fluence groups. Near isotropic angular response was traded for significantly reduced detection time and increased simplicity. Spectral analysis of individual fiber response can provide directional information based on the ratio of energy deposition by thermal neutrons to all neutrons. Future work using proton recoil spectral data from individual fibers will allow increases in energy resolution while reducing or eliminating the need for a priori spectral information.

Determination of the spatial distribution and quantification of concentration of pure beta- and photon-emitting radionuclides in absorbing media by external measurements is the subject of this study. Measurements of radiation and the operation of radiation detectors are based on the radiation interactions with matter and the theory governing these interactions has been discussed. Various techniques for localising pure beta- and photon-emitting radionuclides situated inside attenuating media have been suggested on a theoretical basis, and have been experimentally shown to work successfully. Most of the work is on single photon emission computed tomography (SPECT). The theory of mathematical reconstruction of a two dimensional distribution from its projections is discussed and reconstruction techniques and their relative merits and demerits have been reviewed. SPECT seeks the determination of absolute regional radionuclide concentrations as a function of time. A SPECT system has been developed by modifying an existing transmission CT scanner and the reconstruction algorithms. The performance of the SPECT system has been tested for a number of point sources and various extended sources in gas, liquid and solid forms. The SPECT scanner in its present design is capable of performing in both the transmission and emission modes. The characteristics of the SPECT scanner, including the detector efficiency, spatial resolution and the effect of collimator size, have been studied experimentally. The major problems faced by SPECT include the solid angle effect, which influences the collection efficiency, in scattered radiation, and attenuation of photons inside the surrounding medium. These problems together with their various possible solutions have been discussed in detail. Methods for compensation for solid angle variation, in scattered radiation and photon attenuation have been devised and used successfully to compensate the projection data.

The aim of this study is to devise detection processes for digital modems operating at rates of 9600 bit/s and more over telephone lines, using coded QAM signals. The baseband representation of QAM systems and the signal distortion introduced by the telephone circuits are first investigated to derive a suitable model for the simulation of data transmission systems, using a digital computer.

D.Ing. (Electrical and Electronic Engineering) / The subject of this research work was the reflective fibre optic ring interferometer utilizing allow coherence length source. The interferometer consists of an interrogating fibre connected to a fibre ring via an input/output splitting coupler, and a reflector. The fibre ring is formed between one input and one output leg of a fibre coupler. The reflector can be of any type, including a fibre loop mirror, Faraday rotator mirror, a silvered fibre end-face or multilayer dielectric mirror deposited on the fibre end face. A theoretical treatment was developed for the interferometer. It was shown that the interferometer had a reflectance vs nonreciprocal phase shift characteristic, similar to that of a Fabry-Perot interferometer. Upon phase modulation of the interferometer quadrature terms were obtained at harmonics of the modulation frequency. It was shown that by decreasing the finesse of the sensor a quadrature phase tracker could be employed. The dependence of the sensor's reflectance, finesse and sensitivity on various system parameters were simulated with the aid of the abovementioned theory. A high finesse interferometer was proposed. It utilizes a fibre doped amplifier which would increase the sensitivity above that of a Sagnac interferometer. Intermediate and low finesse versions of the reflective ring interferometer were applied as gyroscopes...

A real need exists for a sensor capable of detecting flow-field separation on an airplane wing during routine flight operations. A sensor of this type could lead to both improved flight safety and increased performance. It would also contribute to future separation control technologies. A new idea is presented for a sensor that is cost effective, easy to maintain, durable, and highly effective. The system, known as a Thermal Grid, works by using a grid of heaters and temperature sensors to trace out the streamlines closest to the surface. Specific singularities in these streamlines are excellent indicators of flow separation. This paper addresses many of the necessary principles that are necessary to making the Thermal Grid an operational device. An analytic design is presented that details the system requirements and potential performance, including heater/sensor spacing, heater power requirements, sensor time response and sensitivity needs and the effects of changes in flow conditions. / Master of Science

Neutrinos hold the promise of untangling many unresolved questions in particle physics. Their unique properties and behaviors offer a distinctive window into understanding the fundamentals of the universe, potentially providing answers to some of the most deep puzzles in modern physics. CEνNS, or Coherent Elastic Neutrino-Nucleus Scattering, is a process where a neutrino interacts with an atomic nucleus and scatters away, leaving the nucleus to recoil. CEνNS is an important area of study for understanding neutrino properties as well as their role in the universe. The COHERENT collaboration was the first to measure CEνNS, using neutrinos from the Spallation Neutron Source (SNS). The direct measurement of the SNS neutrino flux is vital for the precision of CEνNS measurements. This work introduces the latest addition to the COHERENT's armory –a D2O detector specifically designed to measure the SNS neutrino flux. In the present dissertation, the emphasis is made on the steps taken to operationalize COHERENT's D2O detector. This work unfolds the intensive simulation work directed to determine the detector's optimal design, ensuring it stands strong to the demands of neutrino physics experiments. Establishing the detector's calibration is essential to its operational phase. A dedicated calibration system, described in detail in this work, has been developed, utilizing encapsulated LED flashers controlled by a microcontroller unit to ensure the systematic and reliable calibration of the detector. A significant portion of the document is devoted to the calibration analysis, where we use Michel electrons to obtain an energy scale for the detector, thereby ensuring the reliability and accuracy of the future neutrino flux measurements. / Doctor of Philosophy / This dissertation delves into the fascinating world of neutrinos, subatomic particles that travel through space and matter, impacting the universe in many ways. Their elusive nature makes them a fascinating subject of study, as understanding them better can reveal more about the fundamentals of the cosmos. One process involving neutrinos is Coherent Elastic Neutrino-Nucleus Scattering (CEνNS), which is the main focus of the COHERENT experi- ment. CEνNS happens when a neutrino interacts with an atomic nucleus and scatters away. It is a vital field of study as it can provide insights into neutrino properties and behavi- ors, helping us explore many unanswered questions in physics. As part of COHERENT's experimental program, there is the need to measure the neutrino flux directly. This pre- cise measurement is crucial for ensuring the accuracy and reliability of the COHERENT's findings. To achieve this, COHERENT has introduced a new detector, filled with heavy water (D2O), designed to carefully capture and analyze neutrinos. This work outlines the extensive simulation undertaken to ensure the detector's effectiveness. Before the detector can successfully measure neutrino interactions, it must be carefully calibrated. This docu- ment also describes the construction of a unique calibration system, a critical step for the project's success. Finally, this dissertation highlights the development of a detailed calibra- tion analysis, an essential component for ensuring the detector's readings are accurate and trustworthy. This comprehensive preparation is fundamental for the next exciting phases of COHERENT's research into the mysterious world of neutrinos.

Microbeams have been used for radiation biology research since their introduction in the 1950s. A goal since their inception has been to irradiate individual cells and sub-cellular components with individual charged particles. These two criteria have been simultaneously achievable only within the last decade thanks to new technologies capable of producing very thin materials. The McMaster Microbeam Laboratory wishes to conduct such experiments using a proton beam. However, there are presently no commercially available detectors for this application, which necessitates the need for a new detector. Following literature research, a 10 μm thin Schottky diode detector was selected as the most appropriate type of detector for the setup at McMaster. The design of the detector and detection system geometries were optimized to reduce beam scattering and broadening with the aid of TRIM and MCNP simulations. Two detectors were fully constructed. However, a stable response to radiation was not achieved. One of the detectors appeared to function as a radiation detector very briefly but this result was not reproducible. The I-V curve of the detectors proved that they functioned as expected as diodes. However, without a radiation response no further characterization could be completed. Although problem solving efforts to overcome this issue were unsuccessful, a large silicon dopant concentration is suspected to be a possible cause. / Thesis / Master of Science (MSc)

Experimental anomalies hint at the possible existence of a sterile neutrino. Several experiments have been searching for the sterile neutrino, but none can claim either its discovery or fully rule it out. To test the sterile neutrino hypothesis, we search for short baseline oscillations using antineutrinos from nuclear reactors. We have developed a reactor antineutrino detection technology based on solid plastic scintillator, called CHANDLER, which could be used to search for short baseline reactor antineutrino oscillations. An 80 kg prototype was deployed at a commercial nuclear reactor for four and a half months with minimal shielding and no overburden. We detected an antineutrino signal of 2880 inverse beta decay events, with 5.5σ significance. This measurement represents the first observation of reactor antineutrinos in a surface-deployed, mobile neutrino detector. We envisioned several improvements to the detector from this deployment, which will be tested in an upgrade of this prototype. The full-scale detector will be able to search for sterile neutrinos and could also be used for nuclear non-proliferation applications. / Doctor of Philosophy / Along with light, the Sun emits a huge number of particles, called neutrinos. These neutrinos can pass through the matter without interacting as light passes through glass. Only a tiny fraction of neutrinos will interact in the materials through which they pass; therefore, they are extremely difficult to observe. There are three known types of neutrinos, but some theory and experiments require a new type of neutrinos, called a sterile neutrino. Nuclear power plants also emit neutrinos. We have developed a technology to observe these neutrinos from the nuclear power plants. We deployed a small prototype detector at a power plant and observed the neutrinos. From the deployment, we envisioned some improvements that will be tested in an upgraded detector. A full-scale detector will be able to search for sterile neutrinos. The detector might also have some real-life applications. It could be used to detect an elicit extraction of weapons-grade material from the nuclear power plant.

The Clouds and the Earth's Radiant Energy System (CERES) is a program sponsored by the National Aeronautics and Space Administration (NASA) aimed at evaluating the global energy balance. Current scanning radiometers used for CERES consist of thin-film thermistor bolometers viewing the Earth through a Cassegrain telescope. The Thermal Radiation Group, a laboratory in the Department of Mechanical Engineering at Virginia Polytechnic Institute and State University, is currently studying a new sensor concept to replace the current bolometer: a thermopile thermal radiation detector. This next-generation detector would consist of a thermal sensor array made of thermocouple junction pairs, or thermopiles. The objective of the current research is to perform a thermal analysis of the thermopile. Numerical thermal models are particularly suited to solve problems for which temperature is the dominant mechanism of the operation of the device (through the thermoelectric effect), as well as for complex geometries composed of numerous different materials. Feasibility and design specifications are studied by developing a dynamic electrothermal model of the thermopile using the finite element method. A commercial finite element-modeling package, ALGOR, is used. / Master of Science

SuperCDMS is a leading direct dark matter search experiment which uses solid state detectors (Ge crystals) at milliKelvin temperatures to look for nuclear recoils caused by dark matter interactions in the detector. ‘Weakly Interacting Massive Particles’ (WIMPs) are the most favoured dark matter candidate particles. SuperCDMS, like many other direct dark matter search experiments, primarily looks for WIMPs. The measurement of both the ionization and the lattice vibration (phonon) signals from an interaction in the detector allow it to discriminate against electron recoils which are the main source of background for WIMP detection. SuperCDMS currently operates about 9 kgs worth of germanium detectors at the Soudan underground lab in northern Minnesota. In its next phase, SuperCDMS SNOLAB, it plans to use 100-200 kg of target mass (Ge) which would allow it to probe more of the interesting and unexplored parameter space for WIMPs predicted by theoretical models. The SuperCDMS Queen’s Test Facility is a detector testing facility which is intended to serve detector testing and detector research and development purposes for the SuperCDMS experiment. A modified detector called the ‘HiZIP’ (Half-iZIP), which is reduced in complexity in comparison to the currently used iZIP (interleaved Z-sensitive Ionization and Phonon mediated) detectors, is studied in this thesis. The HiZIP detector design also serves to discriminate against background from multiple scatter events occurring close to the surfaces in a single detector. Studies carried out to compare the surface event leakage in the HiZIP detector using limited information from iZIP data taken at SuperCDMS test facility at UC Berkley produce a highly conservative upper limit of 5 out of 10,000 events at 90% confidence level. This upper limit is the best among many different HiZIP configurations that were investigated and is comparable to the upper limit calculated for an iZIP detector in the same way using the same data. A real HiZIP device operated at Queen’s Test Facility produced an exposure limited 90% upper limit of about 1 in 100 events for surface event leakage. The data used in these studies contain true nuclear recoil events from cosmogenic and ambient neutrons. This background was not subtracted in the calculation of the upper limits stated above and hence they are highly conservative. A surface event source was produced by depositing lead-210 from radon exposure onto a copper plate. This source was then used to take data for a surface event discrimination study of the HiZIP detector operated at Queen’s Test Facility. A study of the contribution of the noise from capacitive crosstalk between charge sensors in a HiZIP detector configuration was investigated, confirming the expectation that no significant drop in performance is to be expected due to this effect. / Thesis (Master, Physics, Engineering Physics and Astronomy) -- Queen's University, 2013-09-30 23:48:49.375