Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 418 for “"Positron"”.
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Positron Annihilation lifetime studies of inorganic materials using a new positron beamline
… unique information about a target sample, is Positron Annihilation Spectroscopy (PAS). The initial aim of the research presented here was the development and characterisation of a positron beamline for materials studies. This beamline, now operational, has been developed to measure the …
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Positron Annihilation lifetime studies of inorganic materials using a new positron beamline
… unique information about a target sample, is Positron Annihilation Spectroscopy (PAS). The initial aim of the research presented here was the development and characterisation of a positron beamline for materials studies. This beamline, now operational, has been developed to measure the …
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ATRAP Buffer-Gas Positron Accumulator
… atoms. ATRAP has produced antihydrogen by positron cooling of antiprotons and by a laser-controlled charge-exchange process. Both methods require large numbers of antiprotons and positrons (the constituent particles of antihydrogen). This dissertation describes the methods developed to …
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Low Energy Positron Interactions With Biological Molecules
<p>Calculations of the positron density distribution which can be used for positrons bound to midsize and larger molecules have been tested for smaller molecules and subsequently applied to investigate the most likely e+e- annihilation sites for positrons interacting with biological molecules …
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Novel designs for undulator based positron sources
Proposed high energy electron-positron linear colliders require a high ux of positrons. To achieve this a number of new positron source designs have been proposed. One of these is an undulator-based positron source, which is the baseline positron source design for the International Linear Collider. …
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Investigations into a positron emission imaging algorithm
A positron emission imaging algorithm which makes use of the entire set of lines-of-response in list-mode form is presented. The algorithm parameterises the lines-of-response by a Cartesian mesh over the field-of-view of a Positron Emission Tomography (PET) scanner to find their density …
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Compressive Sensing in Positron Emission Tomography (PET) Imaging
Positron emission tomography (PET) is a nuclear medicine functional imaging modality, applicable to several clinical problems, but especially in detecting the metabolic activity (as in cancer). PET scanners use multiple rings of gamma ray detectors that surround the patient. These scanners are …
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Evaluation of yttrium-90 positron emission tomography dosimetry
… of <sup>90</sup>Y has been shown to allow for positron emission tomography (PET) imaging following radioembolization. This work explores the accuracy and limitation of <sup>90</sup>Y PET imaging due to the extremely low signal to noise (SNR) ratio associated with <sup>90</sup>Y and verifies the …
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Positron Emission Tomography in Oncology and Environmental Science
… nature of a biological environment is the use of positron emission tomography (PET). Excitingly, the efforts of the nuclear medicine community over the past two decades have resulted in a remarkable surge in the use of PET, establishing it as a standard practice and part of routine care in …
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Dark Matter Annihilation and the Observed Positron Excess
… experiments, PAMELA and Fermi, show a flux of positrons above the expected background signal; this positron excess may point toward a primary source of positrons that could be explained by dark matter annihilations. Utilizing DarkSUSY to generate supersymmetric models in which the neutralino is …
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A new beamline for positron annihilation lifetime spectroscopy
… PALS beamline based on a Surko-type buffer gas positron trap, the first of its kind in the world. A significant amount of work has gone into optimization of the timing and intensity characteristics of positron pulse. Successful implantation of 'Mills ideal function' bunching method has led to …
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A new beamline for positron annihilation lifetime spectroscopy
… PALS beamline based on a Surko-type buffer gas positron trap, the first of its kind in the world. A significant amount of work has gone into optimization of the timing and intensity characteristics of positron pulse. Successful implantation of 'Mills ideal function' bunching method has led to …
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Improving Attenuation Correction In Hybrid Positron Emission to mography
<p>Hybrid positron emission tomography imaging techniques such as PET/CT and PET/MR have undergone significant developments over the last two decades and have played increasingly more important roles both in research and in the clinic. A unique advantage PET has over other clinical imaging …
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Motion Detection in Dynamic Cardiac Positron Emission Tomography Images
… cardiac 82Rb PET images.First, we determined if positron-emitting fiducial markers can be used as surrogate markers for heart motion in dynamic PET images. Second, algorithms were developed to track fiducial marker motion. Lastly, we tested the idea that principle component analysis may be able …
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Functional lung imaging in humans using Positron Emission Tomography
… with a method of functional lung imaging using Positron Emission Tomography (PET). In this technique, a radioactive tracer, nitrogen-13, is dissolved in saline solution, and injected into a peripheral vein. By analysis of the tracer kinetics through the lung, measured using PET, a …
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Pair production of W bosons in electron positron annihilation
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Physics, 1998.
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Positron Emission Tomography Phantom Studies for Radiation Therapy Target Delineation
… prevalent in radiation treatment planning (RTP). Positron Emission Tomography (PET) is one form of bioanatomic imaging that is readily used for RTP of non-small-cell lung cancer (NSCLC) and head and neck cancer (H&N). PET utilizes a radiotracer, such as fluro-deoxy glucose (FDG), to detect tumors. …
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Use of Positron Emission to mography For Proton Therapy Verification
<p>Positron emission tomography (PET), a tool commonly used for cancer staging and response monitoring, has recently been used for proton therapy verification. By imaging tissue activation following proton treatment, attempts have been made to verify proton <em>dose</em> and <em>range</em>. In this …
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