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Browsing by Author "Biedron, Sandra, committee member"

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    A comparison of air samples at ground level and aerial gamma count rates from the response to the Fukushima Dai-Ichi Nuclear Power Plant accident
    (Colorado State University. Libraries, 2014) Sublett, Sarah Miriam, author; Brandl, Alexander, advisor; Biedron, Sandra, committee member; Johnson, Thomas, committee member
    March 11, 2011 will be a day that will never be forgotten in the minds of the thousands of Japanese people whose lives were forever changed by a series of natural disasters, including a 9.0 earthquake and subsequent tsunami that triggered the Fukushima Dai-Ichi Nuclear Power Plant (FDNPP), located on the eastern coast of Japan, to become cripplingly damaged. The FDNPP nuclear accident resulted in the emission of radionuclides into the environment and those released nuclides, specifically 134Cs, 137Cs, and 131I and their measurement by ground and air based means, are the subject of this research project. Within the first few days following the start of the disaster, numerous US federal agencies responded and deployed to Japan to help characterize and measure the release of radionuclides from FDNPP. Over the course of approximately a two-month span, over 500,000 measurements were obtained and analyzed, including air and soil samples and in situ spectra. The core of this research project was to analyze and compare ground air samples to aerial gamma count rate measurements obtained in Fukushima Prefecture within the first two months following the disaster. The results of this project estimate the ground deposition of radionuclides in Fukushima Prefecture, which accounted for 99.4% of the measured aerial net gamma count rate. Another finding of this project is the estimated ground deposition of nuclides based upon aerial gamma count rates in areas where there was measurable ground air contamination was 14.25 times higher than in areas where there was no measurable ground air contamination as determined by the evaluated air samples in this project. Of the samples evaluated in this project, ground deposition averaged 5.4E6 Bq/m2 in areas where there was measurable ground air contamination, versus 3.79E5 Bq/m2 in areas where there was no measurable ground air contamination.
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    Electronic dosimeter and thermoluminescent dosimeter correlation study at Catawba Nuclear Station
    (Colorado State University. Libraries, 2014) Edquist, Britt Alyssa, author; Johnson, Thomas, advisor; Brandl, Alexander, committee member; Biedron, Sandra, committee member
    Duke Energy's nuclear fleet is comprised of seven nuclear plants. The dosimetry program at every plant includes a comparison of the dose recorded by the TLDs and EPDs at the end of each quarter. EPD over-response is desirable to a degree because the over-response offers a higher dose estimate; however, too great of an over estimate obscures the actual dose a worker receives. An EPD/TLD correlation study was conducted to quantify and identify factors contributing to excess EPD over-response and offer recommendations to improve the EPD/TLD correlation. The EPD/TLD correlations at Catawba Nuclear Station (CNS) (York, SC) were markedly higher than the EPD/TLD correlations at other Duke Energy nuclear plants. The purpose of this study was to investigate the EPD/TLD correlation experienced at CNS. Assemblies, comprised of a phantom (a one gallon plastic jug filled with water) with a V2/V3 Mirion 2000S EPD, V4 Mirion 2000S EPD and TLD inside of a plastic bag that was zip tied to the phantom, were placed in strategic locations within the CNS auxiliary building. Dose rates in the CNS auxiliary building ranged from approximately 10 μSv/h (1 mrem/h) to 350 μSv/h (35 mrem/h). Assemblies were removed after seven days and the dose from the EPDs and TLDs were determined and recorded. Both the V2/V3 and V4 EPDs over-responded compared to the TLD. The V4 over-response was found to be greater than the V2/V3 over-response. Reducing the V4 EPD bias from 15% to 7% would improve the correlation between EPD and TLD doses while still permitting some over-response, allowing for more meaningful EPD dose estimates.
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    Massive neutrinos and the see saw mechanism
    (Colorado State University. Libraries, 2014) Campbell, Thomas, author; Toki, Walter, advisor; Buchanan, Norm, committee member; Biedron, Sandra, committee member
    In the current standard model of particle physics, neutrinos are massless and strictly left-chiral. With neutrino oscillations definitively observed, we know experimentally that neutrinos have non-zero mass. The standard model for leptons, including the Higgs mechanism for mass generation will be explored. Extensions to the standard model to give neutrinos mass and the so called see-saw mechanism will then be presented. Finally, one model of the see-saw mechanism purposed by S. F. King will then be compared to recent data from the T2K experiment.
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    Measurement of the muon anti-neutrino charged current double differential cross section with no pions in the final state on water using the pi-zero detector at T2K
    (Colorado State University. Libraries, 2018) Campbell, Thomas, author; Toki, Walter, advisor; Biedron, Sandra, committee member; Buchanan, Norm, committee member; Wilson, Robert J., committee member
    The T2K (Tokai to Kamioka) experiment is a long baseline neutrino oscillation experiment where a narrow band (by energy) neutrino beam of primarily muon neutrinos or muon anti-neutrinos is produced in Tokai and directed towards Kamioka in Japan. Neutrinos in the beam are first detected at the T2K near detector complex 280 m from the beam source (ND280) and then travel 295 km before being detected again at the Super-Kamiokande (Super-K) water-Cherenkov detector. In addition to measuring the flux of neutrinos in the T2K beamline en route to Super-K, other physics analyses are performed at ND280. This thesis describes one such measurement where the π0-detector (P∅D) and a time projection chamber at ND280 were used to measure the charged-current cross section for muon anti neutrinos with water as the interaction target and no pions in the final state. Such a cross section is a T2K and world first. This cross section was measured differentially by the outgoing lepton true kinematics using a binned likelihood fitting framework recently developed at T2K. The thesis will provide: an introduction to neutrinos in the context of a cross section measurement, a description of the T2K experiment including common software tools used in analysis, a general discussion of concerns in differential cross section measurements, a mathematical formulation of the likelihood fitting procedure, details of the neutrino event selection process, the chosen parameterization and validation of the fit, and finally, the cross section results in data with a discussion of the significance and conclusions of the measurement. The total cross section integrated over all differential bins considered in the analysis is measured to be: σ = (7.844 ± 1.316) × 10−39 cm2/water molecule.
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    Simulation of radiological background data for benchmarking statistical algorithms to enhance current radiological detection capabilities
    (Colorado State University. Libraries, 2017) LaBrake, Michael A., author; Brandl, Alexander, advisor; Johnson, Thomas, advisor; Biedron, Sandra, committee member
    Reliable methods for detection of nuclear material are essential, particularly when the material is a weak or shielded source. Since weak or shielded sources often require longer measurement times to distinguish between the source distribution and the background distribution, a statistical approach is being developed that will utilize prior information obtained by measurement systems, such as portal monitors, which collect data on a continuous basis. The hypothesis is that patterns can be identified in sequences of repeated count rate measurements and used in conjunction with classical statistics to identify and locate a source. By measuring background distributions and establishing standard data for specific locations, it is possible to use the probability of observing individual count measurement results in successive measurement intervals at or above the critical limit, y*, and use this information to help pinpoint a weak or shielded source. Because radioactive decay and detection of radioactive material are stochastic events, pseudo-random numbers are used in conjunction with a mathematical method that enables simulation of various background distributions. The related y* values are calculated for each distribution and repeated measurements at or above y* are counted and compared to those expected for the given distribution. Four distributions were investigated: the triangular, sinusoidal, normal, and Poisson distributions. For each distribution, large random number samples were generated to confirm the expected probabilities for various sequences of values at or above the decision threshold y*. All investigated sequences found the 95% confidence interval for the expected number of sequences greater than y* to include the observed number of sequences greater than y*.