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Nuclear Engineering

Air Force Institute of Technology

Theses and Dissertations

2005

Articles 1 - 11 of 11

Full-Text Articles in Engineering

Improved Multinuclide Imaging Of Special Nuclear Material Using A High Purity Germanium Double Sided Strip Detector, Fred D. Rothenbush Jr. Jun 2005

Improved Multinuclide Imaging Of Special Nuclear Material Using A High Purity Germanium Double Sided Strip Detector, Fred D. Rothenbush Jr.

Theses and Dissertations

The purpose of this research is to improve the ability to image Special Nuclear Material (SNM) using a High Purity Germanium Double Sided Strip Detector (HPGeDSSD) for use in the field of nuclear nonproliferation. When used for gamma spectrometry, HPGe detectors can efficiently distinguish various isotopes because of their good energy resolution. The detector used for this research is a liquid nitrogen cooled germanium detector with five charge collection strips on each face. The strips are orthogonal to each other, creating a five by five array of data collection pixels. When the 25 mm by 25 mm detector array is …

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Capacitance-Voltage Study On The Effects Of Low Energy Electron Radiation On Al0.27Ga0.73N/Gan High Electron Mobility Transistor, Thomas D. Jarzen Mar 2005

Capacitance-Voltage Study On The Effects Of Low Energy Electron Radiation On Al0.27Ga0.73N/Gan High Electron Mobility Transistor, Thomas D. Jarzen

Theses and Dissertations

The effects of radiation on semiconductors are extremely important to the Department of Defense since the majority of the defense informational, navigational and communications systems are now satellite-based. Due to the high radiation tolerance of gallium nitride and a plethora of high temperature, high power and high frequency applications, the prospect that gallium nitride based devices will become key components in a multitude of military satellite-based systems is highly probable. AlGaN/GaN HEMTs were irradiated at low temperature (~80 K) by 0.45 – 0.8 MeV electrons up to fluences of 1×1015 e-/cm2. Following irradiation, low temperature capacitance-voltage measurements …

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Manufacture And Testing Of An Activation Foil Package For Use In Afids, Warren E. Kimmel Mar 2005

Manufacture And Testing Of An Activation Foil Package For Use In Afids, Warren E. Kimmel

Theses and Dissertations

This study used simulation and experiment to design and test foil packets for use in the Activation Foil Integrated Detection System (AFIDS). The initial plan to activate foil packets outside with the pulse reactor at White Sands Missile Range (WSMR) was not possible due to WSMR not having safety approval to take the reactor outside. As an alternative, the concept of using liquid nitrous oxide inside a reactor to simulate large volumes of air was investigated. Simulation using the Standardized Computer Analyses for Licensing Evaluation (SCALE) program was used to select ten foils to be included in the foil packet. …

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Feasibility Analysis Of A Compton Spectrometer System For Identification Of Special Nuclear Material, Chad C. Schools Mar 2005

Feasibility Analysis Of A Compton Spectrometer System For Identification Of Special Nuclear Material, Chad C. Schools

Theses and Dissertations

Current operational needs require the deployment of radiation detection equipment with the ability to accurately and reliably identify special nuclear materials and their byproducts without dependence on cryogenics. This requires a resolution of 0.5% or less over a range of 200 to 700 keV. The feasibility of a Compton spectrometer to achieve this resolution is examined. The Compton spectrometer system used consists of two detectors. The Compton scatter event occurs in a CdTe detector where the Compton electron energy is collected. Gamma rays scattered out of the CdTe at an angle determined by a conical collimator, are collected in a …

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Classification Of Battlespace Detonations From Temporally Resolved Mutli-Band Imagery And Mid-Infrared Spectra, Anthony N. Dills Mar 2005

Classification Of Battlespace Detonations From Temporally Resolved Mutli-Band Imagery And Mid-Infrared Spectra, Anthony N. Dills

Theses and Dissertations

The classification of battlespace detonations, specifically the determination of munitions type and size using temporal and spectral features, has been studied using near-infrared (NIR) and multi-color visible wavelength imagers. Key features from the time dependence of fireball size are identified for discriminating various types and sizes of detonation flashes. The five classes include three weights of trinitrotoluene (TNT) and two weights of an enhanced mixture, all of which are uncased and detonated with 10% C4. Using Fisher linear discriminant techniques, features are projected onto a line such that the projected points are maximally clustered for the different classes of detonations. …

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Development Of 2-Dimensional Cloud Rise Model To Analyze Initial Nuclear Cloud Rise, Karson A. Sandman Mar 2005

Development Of 2-Dimensional Cloud Rise Model To Analyze Initial Nuclear Cloud Rise, Karson A. Sandman

Theses and Dissertations

The objective of this research is to create a two-dimensional cloud rise model that could be used instead of the current one-dimensional cloud rise model in the Defense Land Fallout Intepretive Code (DELFIC) option of the Hazard Prediction and Assessment Capability (HPAC). The model includes numerical analysis of partial differential equations involving pressure, potential temperature, horizontal and vertical winds, and specific humidity. The 2-D model developed provides a much more detailed definition of the physical properties within the mushroom cloud than the 1-D DELFIC option. This is particularly useful in fallout studies on particle formation, fractionation, and particle location within …

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A Comparison Of Hazard Predication And Assessment Capability (Hpac) Software Dose-Rate Contour Plots To A Sample Of Local Fallout Data From Test Detonations In The Continental United States, 1945-1962, Richard W. Chancellor Mar 2005

A Comparison Of Hazard Predication And Assessment Capability (Hpac) Software Dose-Rate Contour Plots To A Sample Of Local Fallout Data From Test Detonations In The Continental United States, 1945-1962, Richard W. Chancellor

Theses and Dissertations

A comparison of Hazard Prediction and Assessment Capability (HPAC) software dose-rate contour plots to a sample of local nuclear fallout data from test detonations in the continental United States, 1945 - 1962, is performed. Fallout data from test detonations is obtained from "Compilation of Local Fallout Data from Test Detonations 1945- 1962 Extracted from DASA 1251, Volume I - Continental U.S. Tests." This report contains fallout plots and radiation contours for each test in the atmospheric nuclear test program conducted by the United States prior to 1963. These plots are compared with the plots resulting from Defense Threat Reduction Agency's …

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Lethality Of Bacillus Anthracis Spores Due To Short Duration Heating Measured Using Infrared Spectroscopy, Kristina M. Goetz Mar 2005

Lethality Of Bacillus Anthracis Spores Due To Short Duration Heating Measured Using Infrared Spectroscopy, Kristina M. Goetz

Theses and Dissertations

There are a number of analytical and semi-empirical models that describe the behavior of particulate matter in the atmosphere. Many of these require modification for all types of weather, dry versus wet deposition, and overall effects can be quite non-linear. Rainfall (rate, drop size, etc.), snowfall (rate, flake size, etc.), humidity, pressure, temperature, and combination of these greatly affect particle settling and washout rates. To that end, a method for tracking released constituents using the Regional Atmospheric Modeling System (RAMS) microphysics package is developed by modifying one of the hydrometeor categories (hail) in the microphysics package. The RAMS microphysics package …

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Temperature Dependent Current-Voltage Measurements Of Neutron Irradiated Al0.27Ga0.73N/Gan Modulation Doped Field Effect Transistors, Troy A. Uhlman Mar 2005

Temperature Dependent Current-Voltage Measurements Of Neutron Irradiated Al0.27Ga0.73N/Gan Modulation Doped Field Effect Transistors, Troy A. Uhlman

Theses and Dissertations

In this research, the first ever neutron irradiation study of AlGaN/GaN MODFETs was conducted. Devices irradiated to a total 1 MeV Eq (Si) neutron fluence of 1.2x1016 n/sq cm demonstrated the temperature dependence of irradiation and annealing. Devices irradiated at 80 K exhibited significant persistent electrical degradation at only 5.4 rad (Si), whereas those irradiated at elevated temperatures exhibit transient increases in gate and drain current up to 400 krad (Si). I-V measurements indicate substantial radiation-induced increased gate and drain currents occur only at low-temperature irradiations. The introduction of a high-density of donor defects is hypothesized as the primary …

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Surface Oxidation Study Of Uranium Dioxide Under Wet And Dry Conditions, Gary T. Brett Mar 2005

Surface Oxidation Study Of Uranium Dioxide Under Wet And Dry Conditions, Gary T. Brett

Theses and Dissertations

The surface oxidation of pressed uranium dioxide (UO2) powder under controlled environmental conditions and the oxidation and reduction of pressed uranium trioxide (UO3) powder are presented. This is a continuing research project in the investigation of the oxidation of UO2 powder using Photoluminescence (PL) Spectroscopy. UO2 particles exposed to the ambient atmosphere will oxidize into a number of chemical complexes (specifically hydrates, hydroxides, and carbonates). During certain of these oxidation processes, the uranium ion can lose two of its electrons and change from uranous (UIV+) to uranyl (UVI+). This research …

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A Comparison Of The Heft Subsurface And Delfic Particle Size Distributions And Effects In Hpac, Eric T. Skaar Mar 2005

A Comparison Of The Heft Subsurface And Delfic Particle Size Distributions And Effects In Hpac, Eric T. Skaar

Theses and Dissertations

The Heft subsurface three component lognormal fallout particle size distribution is compared and contrasted with the single lognormal fallout particle size distribution used by the Defense Land Fallout Interpretive Code (DELFIC). Comparison of the two distributions is accomplished with results from the AFIT smear code and the Hazard Prediction and Assessment Capability (HPAC). The effect of the distributions is explored in HPAC for varying yield weapons, varying surfaces, precipitation conditions, varying wind effects and varying dose rate times. The results from the two distributions are quantitatively compared using the concepts of grounded source normalization constant and the rate at which …

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