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Articles 61 - 90 of 179
Full-Text Articles in Nuclear Engineering
A Machine Learning Approach To Characterizing Particle Morphology In Nuclear Forensics, Daniel A. Gum
A Machine Learning Approach To Characterizing Particle Morphology In Nuclear Forensics, Daniel A. Gum
Theses and Dissertations
A machine learning approach is taken to characterizing a group of synthetic uranium bearing particles. SEM images of these lab-created particles were converted into a binary representation that captured morphological features in accordance with a guide established by Los Alamos National Laboratory. Each particle in the dataset contains an association with chemical creation conditions: processing method, precipitation temperature and pH, calcination temperature are most closely tied to particle morphology. Additionally, trained classifiers are able to relate final products between particles, implying that morphological features are shared between particles with similar composition.
Rapid Analysis Of Plutonium Surrogate Material Via Hand-Held Laser-Induced Breakdown Spectroscopy, Ashwin P. Rao
Rapid Analysis Of Plutonium Surrogate Material Via Hand-Held Laser-Induced Breakdown Spectroscopy, Ashwin P. Rao
Theses and Dissertations
This work investigated the capability of a portable LIBS device to detect and quantify dopants in plutonium surrogate alloys, specifically gallium, which is a common stabilizer used in plutonium alloys. The SciAps Z500-ER was utilized to collect spectral data from cerium-gallium alloys of varying gallium concentrations. Calibration models were built to process spectra from the Ce-Ga alloys and calculate gallium concentration from spectral emission intensities. Univariate and multivariate analysis techniques were used to determine limits of detection of different emission line ratios. Spatial mapping measurements were conducted to determine the device's ability to detect variations in gallium concentration on the …
Determination Of Lithium Isotope Concentration By Laser Induced Breakdown Spectroscopy Using Chemometrics, Jason C. Wood
Determination Of Lithium Isotope Concentration By Laser Induced Breakdown Spectroscopy Using Chemometrics, Jason C. Wood
Theses and Dissertations
The role of enriched 6Li in nuclear applications makes the ability to detect and monitor lithium enrichment activity imperative. Detecting levels of enrichment of this isotope currently requires sensitive, complex equipment operated by highly-trained technicians, which is prohibitive to rapid detection of enrichment activity. While commercial companies market portable laser induced breakdown spectroscopy (LIBS) with the ability to detect elements on the order or parts per million concentrations, they have not yet been demonstrated to possess the ability to quantitatively determine isotopic concentrations of lithium. This research performs single-pulse LIBS experiments under laboratory conditions to determine concentrations of 7Li and …
Determination And Simulation Of The Neutron Spectrum Of Nuclear Detonations And Surrogate Sources, Taylor M. Nichols
Determination And Simulation Of The Neutron Spectrum Of Nuclear Detonations And Surrogate Sources, Taylor M. Nichols
Theses and Dissertations
This research determined a methodology for characterizing the Fast Beam Facility (FBF) at The Ohio State University Nuclear Reactor Laboratory to test the response of photovoltaic arrays to nuclear weapon radiation. Additionally, this research developed neutron and gamma nuclear weapon output spectra of two environments for comparison to the FBF spectrum. A Bonner sphere spectrometer (BSS), coupled with the unfolding program Maximum Entropy Deconvolution (MAXED), was employed as a means of determining the energy spectrum of neutrons. Using the ISO 8529 americium beryllium (AmBe) source as the a priori default spectrum, MAXED was used to unfold the spectrum of neutrons …
Neutron Energy Effects On Asteroid Deflection, Lansing S. Horan Iv
Neutron Energy Effects On Asteroid Deflection, Lansing S. Horan Iv
Theses and Dissertations
In the future, a hazardous asteroid will find itself on a collision course with Earth. It is an inevitability; the question is not if, but when. For asteroids of moderate size or larger, a nuclear device is one of humanity's only technologies capable of mitigating this threat via deflection on a timescale of less than a decade. This work examined how changing the output neutron energy from a nuclear device detonation affects asteroid deflection. The notional asteroid target was 300 meters in diameter and composed of silicon dioxide at a bulk density of 1.855 g/cm3. To calculate the …
Neutron Displacement Damage In Germanium Tin Photodiodes, Nathan J. Gale
Neutron Displacement Damage In Germanium Tin Photodiodes, Nathan J. Gale
Theses and Dissertations
GeSn is a promising material for photodiodes in the near-to-mid infrared (IR) spectrum because of new growth methods that enable integration with complementary metal oxide semiconductor (CMOS) technology. While natural germanium has a threshold wavelength of 1800 nm, 6.9 Sn content extends the threshold wavelength to 2700 nm based on a Sn content dependent bandgap. Also, unlike other semiconductors that require liquid nitrogen cooling to act as an IR sensor, GeSn can be operated at room temperature, enabling a wide variety of applications. In this study, photodiodes ranging from 0 to 6.9 tin content were subjected to 1 MeV (Si) …
Nuclear Data Covariance Analysis In Radiation-Transport Simulations Utilizing Scale Sampler And The Irdff Nuclear Data Library, Nicholas J. Quartemont, Abigail A. Bickley, James E. Bevins
Nuclear Data Covariance Analysis In Radiation-Transport Simulations Utilizing Scale Sampler And The Irdff Nuclear Data Library, Nicholas J. Quartemont, Abigail A. Bickley, James E. Bevins
Faculty Publications
This article describes the nuclear data covariance analysis of an experimental design for a neutron energy-tuning assembly (ETA) created to shape a 14-MeV neutron point source to an objective spectrum. Underlying nuclear data uncertainties play a large role in the radiation transport and reaction rates for the range of responses to be expected from an experiment. The methodology leveraged the Standardized Computer Analysis for Licensing Evaluation (SCALE) Sampler module to determine the uncertainty in the neutron transport. The reaction uncertainty was perturbed with the International Reactor Dosimetry and Fusion File v.1.05 uncertainty, correlation matrix, and reaction cross section through multivariate …
Analysis Of An Energy Tuning Assembly For Simulating Nuclear Weapon Environments At The National Ignition Facility, Nicholas J. Quartemont, James E. Bevins, Rachel N. Slaybaugh, Lee A. Bernstein
Analysis Of An Energy Tuning Assembly For Simulating Nuclear Weapon Environments At The National Ignition Facility, Nicholas J. Quartemont, James E. Bevins, Rachel N. Slaybaugh, Lee A. Bernstein
Faculty Publications
An energy tuning assembly ETA was developed to spectrally shape the National Ignition Facility NIF deuterium-tritium D-T fusion neutron source to a notional thermonuclear and prompt fission neutron spectrum TNPFNS to approximate a boosted nuclear device. The spectrally shaped neutron environment can be used to create realistic synthetic post-detonation weapon debris that contain spectrally accurate fission products across all mass chains to enhance U.S. technical nuclear forensics capabilities for nuclear weapon attribution and device reconstruction. This research performed nuclear data covariance analysis through stochastic sampling techniques to predict the performance of an ETA to create the objective TNPFNS, assess anticipated …
Monte Carlo And Experimental Analysis Of A Novel Directional Rotating Scatter Mask Gamma Detection System, Julie V. Logan, Darren E. Holland, Larry W. Burggraf, Justin A. Clinton, Buckley E. O'Day Iii
Monte Carlo And Experimental Analysis Of A Novel Directional Rotating Scatter Mask Gamma Detection System, Julie V. Logan, Darren E. Holland, Larry W. Burggraf, Justin A. Clinton, Buckley E. O'Day Iii
Faculty Publications
Excerpt: This work demonstrates successful experimental operation of a prototype system to identify source direction which was modeled using a library of signals simulated using GEANT and a novel algorithm....
Possible Detection Of Low Energy Solar Neutrons Using Boron Based Materials, Nicole Benker, Elena Echeverria, Robert Olesen, Brant E. Kananen, John W. Mcclory, Yaroslav V. Burak, Volodymyr T. Adamiv, Ihor M. Teslyuk, George Glenn Peterson, Ben Bradley, Ethiyal R. Wilson, James C. Petrosky, Bin Dong, Jeffry Kelber, Jennifer Hamblin, Jaques Doumani, Peter A. Dowben, Alex Enders
Possible Detection Of Low Energy Solar Neutrons Using Boron Based Materials, Nicole Benker, Elena Echeverria, Robert Olesen, Brant E. Kananen, John W. Mcclory, Yaroslav V. Burak, Volodymyr T. Adamiv, Ihor M. Teslyuk, George Glenn Peterson, Ben Bradley, Ethiyal R. Wilson, James C. Petrosky, Bin Dong, Jeffry Kelber, Jennifer Hamblin, Jaques Doumani, Peter A. Dowben, Alex Enders
Faculty Publications
Solar neutrons have been detected aboard the International Space Station (ISS), using lithium tetraborate and boron carbide detector elements. We find that evidence of a solar neutron flux, as detected in a neutron calorimeter following subtraction of the proton background, with an energy of about 2 to 4 MeV. This solar neutron flux is likely no more than 250 to 375 neutrons cm−2sec−1, with a lower bound of 50–75 neutrons cm−2sec−1 at one au.
Enabling Mobile Neutron Detection Systems With Clyc, Matthew C. Recker
Enabling Mobile Neutron Detection Systems With Clyc, Matthew C. Recker
Theses and Dissertations
Cs2LiYCl6:Ce3+ (CLYC) has the desirable property of being sensitive to both gamma rays and neutrons while producing waveforms suitable for pulse shape discrimination (PSD) to determine which radiation was detected. This dissertation examines the behavior of CLYC to support its further development for mobile and portable applications. First, the feasibility of performing PSD with CLYC and an inexpensive data acquisition system was examined. This system was able to clearly distinguish both events with a figure of merit of 1.42. Next, the performance of a SiPM was compared to a traditional PMT. Analysis showed that the …
Investigations Of Point Defects In Kh2Po4 Crystals Using Ab Initio Quantum Methods, Tabitha E. R. Dodson
Investigations Of Point Defects In Kh2Po4 Crystals Using Ab Initio Quantum Methods, Tabitha E. R. Dodson
Theses and Dissertations
Potassium dihydrogen phosphate (KH2PO4, or commonly called KDP) crystals can be grown to large sizes and are used for many important devices (fast optical switches, frequency conversion, polarization rotation) for high powered lasers. The nonlinear optical material has a wide intrinsic transparency range. Intrinsic point defects are responsible for several short-lived absorption bands in the visible and ultraviolet regions that affect high-power pulsed laser propagation. The primary intrinsic defects have been experimentally detected in KDP using electron paramagnetic resonance (EPR) experiments. The defect models established thus far include (i) self-trapped holes, (ii) oxygen vacancies, and (iii) …
Quantitative Analysis Of Cerium-Gallium Alloys Using A Hand-Held Laser Induced Breakdown Spectroscopy Device, Ashwin P. Rao, Matthew Cook, Howard L. Hall, Michael B. Shattan
Quantitative Analysis Of Cerium-Gallium Alloys Using A Hand-Held Laser Induced Breakdown Spectroscopy Device, Ashwin P. Rao, Matthew Cook, Howard L. Hall, Michael B. Shattan
Faculty Publications
A hand-held laser-induced breakdown spectroscopy device was used to acquire spectral emission data from laser-induced plasmas created on the surface of cerium-gallium alloy samples with Ga concentrations ranging from 0–3 weight percent. Ionic and neutral emission lines of the two constituent elements were then extracted and used to generate calibration curves relating the emission line intensity ratios to the gallium concentration of the alloy. The Ga I 287.4-nm emission line was determined to be superior for the purposes of Ga detection and concentration determination. A limit of detection below 0.25%was achieved using a multivariate regression model of the Ga I …
Point Defects In Lithium Gallate And Gallium Oxide, Christopher A. Lenyk
Point Defects In Lithium Gallate And Gallium Oxide, Christopher A. Lenyk
Theses and Dissertations
Electron paramagnetic resonance (EPR), Fourier-Transform Infrared spectroscopy (FTIR), photoluminescence (PL), thermoluminescence (TL), and wavelength-dependent TL are used to identify and characterize point defects in lithium gallate and β-gallium oxide doped with Mg and Fe acceptor impurities single crystals. EPR investigations of LiGaO2 identify fundamental intrinsic cation defects lithium (V−Li) and gallium (V2−Ga) vacancies. The defects’ principle g values are found through angular dependence studies and atomic-scale models for these new defects are proposed. Thermoluminescence measurements estimate the activation energy of lithium vacancies at Ea = 1.05 eV and gallium vacancies at Ea > 2 …
Nuclear Engineering At The Air Force Institute Of Technology: A Unique Graduate School Experience For A Unique Set Of Students, Michael B. Shattan
Nuclear Engineering At The Air Force Institute Of Technology: A Unique Graduate School Experience For A Unique Set Of Students, Michael B. Shattan
Faculty Publications
In August 2018, the Air University Commander formed a task force to review the Air Force’s Science, Technology, Engineering, and Mathematics (STEM) graduate education programs that are delivered and administered through the Air Force Institute of Technology (AFIT). The study was rooted in strategies to support the 2018 National Defense Strategy, and provided the necessary technologically equipped personnel for the 21st century. The study was commonly referred to as “reimagining AFIT”. Several themes emerged from the study, which include reaching a broader community of Airmen through alternate educational modes (e.g. distance learning, short course etc.), forming strategic educational and research …
Uranium Dioxide Actinide Detection Device Support Design For Space Applications, Jennifer N. Ramos
Uranium Dioxide Actinide Detection Device Support Design For Space Applications, Jennifer N. Ramos
Theses and Dissertations
Attention concerning the proliferation of nuclear weapons and materials has generated many research initiatives to detect, identify, and locate radiation emitted by actinides. In support of this effort, the `Fission Induced Neutron Detection of Nuclear Materials' (FIND'NM) program was established to comprise a joint effort to explore this issue. The objective also co-extends the Air Force Research Laboratory uranium dioxide (UO2) detection sample growth, characterization, and electrical interface research. AFIT's study accomplishes the design and fabrication of a space-tolerant PCB to support a UO2-based neutron detector. Further design considerations are made with the expectation of the platform to be inside …
Development Of A Mixed-Radiation Directional Rotating Scatter Mask Detection System, Bryan V. Egner
Development Of A Mixed-Radiation Directional Rotating Scatter Mask Detection System, Bryan V. Egner
Theses and Dissertations
Previous work demonstrated gamma-ray directional detection through the integration of a radiation detection system and an additively manufactured rotating scatter mask (RSM). This work advances the RSM directional detection system through improvements in the system's design, validation of a new scatter mask, and the novel ability to directionally detect both neutrons and gamma rays, a desirable feature for many nuclear safeguard and counterproliferation applications. The mixed-radiation RSM system developed for this research utilized the Spartan I mask design coupled with a 1" EJ-309 liquid scintillator. A GEome-try ANd Tracking (Geant4) model is developed and quantitatively compared to experimental measurements for …
Nuclear Data Covariance Analysis Of An Energy Tuning Assembly For Simulating Nuclear Weapon Environments, Nicholas J. Quartemont
Nuclear Data Covariance Analysis Of An Energy Tuning Assembly For Simulating Nuclear Weapon Environments, Nicholas J. Quartemont
Theses and Dissertations
An energy tuning assembly was characterized to spectrally shape the National Ignition Facility neutron source to a notional thermonuclear and prompt fission neutron spectrum to approximate a boosted nuclear device. This research performed nuclear data covariance analysis to predict the performance of the energy tuning assembly to create the objective spectrum, assessed anticipated experimental outcomes, and determine the fission products produced in a highly enriched uranium foil in the sample cavity. Nuclear data covariance impacted the neutron fluence energy distribution by a few percent for a large energy range of the neutron fluence. Neutron flux unfolding techniques provided broad spectral …
Evaluation Of Eu:Licaf For Neutron Detection Utilizing Sipms And Portable Electronics, Michael A. Ford, Buckley E. O'Day Iii, John W. Mcclory, Manish K. Sharma, Areg Danagoulian
Evaluation Of Eu:Licaf For Neutron Detection Utilizing Sipms And Portable Electronics, Michael A. Ford, Buckley E. O'Day Iii, John W. Mcclory, Manish K. Sharma, Areg Danagoulian
Faculty Publications
With the increasing cost and decreasing availability of 3He, there have been many efforts to find alternative neutron detection materials. Lithium calcium aluminum fluoride (LiCAF) enriched to 95% 6Li doped with europium was evaluated here as a replacement material for 3He. Wafers 0.5 cm thick, consisting of LiCAF crystals in a rubberized matrix, were embedded with wavelength shifting fibers (WSF) and mated to silicon photo-multipliers (SiPMs) to measure the photon response in a flux of neutrons from a DD neutron generator. Excellent discrimination was realized between neutrons and gammas, and both pulse-height discrimination and pulse-shape analysis were …
Neutron Spectroscopy Using Rubberized Eu:Licaf Wafers, Michael A. Ford
Neutron Spectroscopy Using Rubberized Eu:Licaf Wafers, Michael A. Ford
Theses and Dissertations
With the increasing cost and decreasing availability of 3He, there have been many efforts to find alternative neutron detection materials. Lithium calcium aluminum fluoride (LiCAF) enriched to 95% 6Li doped with europium was evaluated here as a replacement material for 3He, based on the absorption of thermalized neutrons by the 6Li and subsequent energy release of the 6Li(n,t)4He reaction. Wafers 0.5 cm thick, consisting of LiCAF crystals in a rubberized matrix, were embedded with wavelength shifting fibers (WSF) and mated to silicon photo-multipliers (SiPMs) to measure the photon response in a flux of …
Developments In Capture- Γ Libraries For Nonproliferation Applications, A. M. Hurst, R. B. Firestone, B. W. Sleaford, D. L. Bleuel, M. S. Basunia, F. Becvar, T. Belgya, L. A. Bernstein, J. J. Carroll, B. Detwiler, J. E. Escher, C. Genreith, B. L. Goldblum, M. Krticka, A. G. Lerch, David A. Matters, John W. Mcclory, Stephen R. Mchale, Zs. Revay, L. Szentmiklosi, D. Turkoglu, A. Ureche, J. Vulic
Developments In Capture- Γ Libraries For Nonproliferation Applications, A. M. Hurst, R. B. Firestone, B. W. Sleaford, D. L. Bleuel, M. S. Basunia, F. Becvar, T. Belgya, L. A. Bernstein, J. J. Carroll, B. Detwiler, J. E. Escher, C. Genreith, B. L. Goldblum, M. Krticka, A. G. Lerch, David A. Matters, John W. Mcclory, Stephen R. Mchale, Zs. Revay, L. Szentmiklosi, D. Turkoglu, A. Ureche, J. Vulic
Faculty Publications
The neutron-capture reaction is fundamental for identifying and analyzing the γ-ray spectrum from an unknown assembly because it provides unambiguous information on the neutron-absorbing isotopes. Nondestructive-assay applications may exploit this phenomenon passively, for example, in the presence of spontaneous-fission neutrons, or actively where an external neutron source is used as a probe. There are known gaps in the Evaluated Nuclear Data File libraries corresponding to neutron-capture γ-ray data that otherwise limit transport-modeling applications. In this work, we describe how new thermal neutron-capture data are being used to improve information in the neutron-data libraries for isotopes relevant to nonproliferation applications. We …
Reconfigurable Liquid Attenuated Collimator, Larry W. Burggraf, Benjamin R. Kowash, Jack G. M. Fitzgerald
Reconfigurable Liquid Attenuated Collimator, Larry W. Burggraf, Benjamin R. Kowash, Jack G. M. Fitzgerald
AFIT Patents
A reconfigurable radiographic aperture mask collimator apparatus includes a body portion configured to receive an attenuating liquid having a first attenuation value per unit volume. The apparatus further includes a grid portion mated to a face of the body portion and a plurality of passageways each having a cross sectional area and a length. The plurality of passageways is disposed within the grid portion. A plurality of plugs is slidably disposed within the plurality of passageways, and each of the plurality of plugs has a second attenuation value per unit volume less than the first attenuation value. One of the …
Investigation Of 186Re Via Radiative Thermal-Neutron Capture On 185Re, David A. Matters, Andrew G. Lerch, A. M. Hurst, L. Szentmiklosi, J. J. Carroll, B. Detwiler, Zs. Revay, John W. Mcclory, Stephen R. Mchale, R. B. Firestone, B. W. Sleaford, M. Krticka, T. Belgya
Investigation Of 186Re Via Radiative Thermal-Neutron Capture On 185Re, David A. Matters, Andrew G. Lerch, A. M. Hurst, L. Szentmiklosi, J. J. Carroll, B. Detwiler, Zs. Revay, John W. Mcclory, Stephen R. Mchale, R. B. Firestone, B. W. Sleaford, M. Krticka, T. Belgya
Faculty Publications
Partial ��-ray production cross sections and the total radiative thermal-neutron capture cross section for the 185Re(n,��)186Re reaction were measured using the Prompt Gamma Activation Analysis facility at the Budapest Research Reactor with an enriched 185Re target. The 186Re cross sections were standardized using well-known 35Cl(n,��)36Cl cross sections from irradiation of a stoichiometric natReCl3 target. The resulting cross sections for transitions feeding the 186Re ground state from low-lying levels below a cutoff energy of Ec=746keV were combined with a modeled probability of ground-state feeding from levels above E …
Neutron Versus Gamma Radiation Effects On Ytterbium-Doped Optical Fibers, Olivia M. Borman
Neutron Versus Gamma Radiation Effects On Ytterbium-Doped Optical Fibers, Olivia M. Borman
Theses and Dissertations
Multimode ytterbium-doped optical fibers (YDFs) are increasingly utilized in military applications involving fiber lasers and amplifiers. YDFs were irradiated with three different radiation sources (neutron, gamma, and mixed gamma/neutron) in order to determine the independent effects that gamma and neutron radiation have on the fibers. The transmission spectra of the fibers were measured during each irradiation and the spectral shapes and attenuation were compared at similar doses. Comparisons of the spectra showed that gamma radiation results in increased attenuation over the 550-975 nm wavelengths. Fast neutrons were found to contribute to increased attenuation near 500 nm. Neutron radiation also caused …
Radiation Response From A Novel Uo2 Crystal, Stephan A. Varga
Radiation Response From A Novel Uo2 Crystal, Stephan A. Varga
Theses and Dissertations
The radiation response of a novel, single-crystalline UO2 sample was analyzed using several types of radiation. The crystal was exposed to alpha, gamma, and neutron radiation under various environmental conditions and the electronic response of the crystal was measured using a pulse shape discrimination algorithm. The distributions of pulse amplitude (Vmax) and pulse decay times (τ) were used to compare the output. This research revealed that the crystal radiation response is exceptionally sensitive to surface conditions, specifically humidity, which tends to alter the time dependent currents resulting from the radiation interactions. The pulse τ can be made to …
Evaluation Of The Visible Infrared Imaging Radiometer Suite (Viirs) Cloud Base Height (Cbh) Pixel-Level Retrieval Algorithm For Single-Layer Water Clouds, Kyle E. Fitch
Theses and Dissertations
Evaluation of the Visible Infrared Imaging Radiometer Suite (VIIRS) Cloud Base Height (CBH) product was accomplished. CBH is an important factor for aviation, but a lack of coverage for ground-based retrieval is a significant limitation. Space-based retrieval is essential; therefore, the VIIRS CBH pixel-level retrieval algorithm was assessed for single-layer water clouds. Accurate (truth) measurements were needed not only for the CBH product, but also for VIIRS cloud optical thickness (COT), effective particle size (EPS), and cloud top height (CTH). Data from Atmospheric Radiation Measurement (ARM) sites were used, with VIIRS-ARM matchups created from June 2013 through October 2015 for …
Differential (P, P′) And (P, D) Cross Sections Of 89Y And 92Zr, Molly A. Wakeling
Differential (P, P′) And (P, D) Cross Sections Of 89Y And 92Zr, Molly A. Wakeling
Theses and Dissertations
Differential cross sections for the (p, p′) and (p, d) reactions on 89Y and 92Zr were measured using a 28.25-MeV proton beam at the 88-inch cyclotron at Lawrence Berkeley National Laboratory. Angular distributions were obtained for the ground state and several excited states of each isotope using silicon detector telescopes over angles 10° to 140° in the reaction plane. These data were obtained by fitting a Gaussian function to each peak in the energy spectra and integrating the number of counts under each peak. These cross sections will be included in nuclear structure models …
Analysis Of Neutron Effects For Asteroid Disruption, Aaron J. Ferguson
Analysis Of Neutron Effects For Asteroid Disruption, Aaron J. Ferguson
Theses and Dissertations
The use of nuclear weapons is one possible method for disrupting or deflecting an asteroid on a trajectory to impact the earth. A largely unexplored component of weapon yield in a disruption scenario is the impact of the neutron output. The results of MCNP-6 simulations are presented demonstrating the effect that incident neutron energy has on the total energy deposited in an asteroid, including that the efficiency of energy deposition in a material is inversely proportional to the incident neutron energy due to negative Q-value reactions. The effects of material composition on the total energy deposited as well as the …
Nuclear Forensics Applications Of Principal Component Analysis On Micro X-Ray Fluorescence Images, Sarah T. Castro
Nuclear Forensics Applications Of Principal Component Analysis On Micro X-Ray Fluorescence Images, Sarah T. Castro
Theses and Dissertations
A method is developed for rapid detection and analysis of actinides and correlated materials in nuclear fallout debris using principal component analysis on quantified micro x-ray fluorescence intensity values. This method is then applied to address goals of nuclear forensics. The first implementation is a collaborative effort with the National Institute of Standards and Technology and the Federal Bureau of Investigation Laboratory to produce a standard reference material that is a surrogate for glassy nuclear fallout debris in a modern urban environment. This reference material will enable researchers in the development and validation of nuclear forensics methods. A method for …
Applications Of Correlated 2d-Acar And Cdbar Using A Low-Energy Positron Beam, Angelo M. Bonavita
Applications Of Correlated 2d-Acar And Cdbar Using A Low-Energy Positron Beam, Angelo M. Bonavita
Theses and Dissertations
The three-dimensional positron annihilation spectroscopy system (3D-PASS) at the Air Force Institute of Technology (AFIT) correlates coincidence Doppler broadening of annihilation radiation with two-dimensional angular correlation of annihilation radiation measurements using two position-sensitive, high-purity germanium (HPGe) detectors. The low photoelectric cross section of germanium, combined with the limited output of the radioisotope-based positron beam, produced sparse data necessitating careful data extraction. Processing techniques employed to increase 3D-PASS spectra quality include an improved algorithm for determining radiation-interaction position on HPGe double-sided strip detectors, a momentum sampling function based correction scheme and spectra folding informed by crystal symmetries. The 3D nature of …