Nuclear Commons^™

Characterization Of A Boron Carbide Heterojunction Neutron Detector, James E. Bevins

Theses and Dissertations

New methods for neutron detection have become an important area of research in support of national security objectives. In support of this effort, p-type B₅C on n-type Si heterojunction diodes have been built and tested. This research sought to optimize the boron carbide (BC) diode by coupling the nuclear physics modeling capability of GEANT4 and TRIM with the semiconductor device simulation tools. Through an iterative modeling process of controllable parameters, optimal device construction was determined such detection efficiency and charge collection were optimized. This allows an estimation of expected charge collection and efficiency given a set of operating …

Combined Effects Of Radio Frequency And Electron Radiation On Cmos Inverters, Kristofer R. Dahl

Theses and Dissertations

This research examines the measurement methodology, and the results of, the combined effects of electron and radio frequency irradiation (500kHz) on a CMOS Hex Inverter, CD4069UB. There have been many studies in recent years on the effects of electron radiation and electromagnetic interference on integrated circuits, however the combined effects have not been measured. A major obstacle for in-situ electron irradiation experiments is the over current hazard that exists to measurement equipment that comes from taking real-time, in-situ measurements. To overcome this, a test circuit was designed and built to allow for real-time in-situ measurement of the output voltage, current …

Cathodoluminescence And Photoemission Of Doped Lithium Tetraborate, Christina L. Dugan

Theses and Dissertations

Lithium tetraborate (Li₂B₄O₇) crystals are being developed for possible use in solid state neutron detectors. The ⁶Li(n,α)³H and ¹⁰B(n,α)⁷Li reactions are the basis for neutron detection, and a Li₂B₄O₇ crystal enriched with Mn should show improved efficiency for neutron detection. There is a lack of fundamental characterization information regarding this useful material, particularly with regard to its electronic configuration. Photoemission spectroscopy was used to determine the energy level structure of the Mn doped Li₂B₄O₇ crystals. …

Changes To Electrical Conductivity In Irradiated Carbon Nanocomposites, Nickolas A. Duncan

Theses and Dissertations

Carbon nanotubes (CNT) and carbon nanofibers (CNF) are two nanoparticles incorporated in a polymer to create a composite material. These composites are two potential lightweight materials for use as replacements for aluminum structures on satellite systems. Both composite materials have a low resistivity that is consistent with conductive materials. However, the CNT composite is substantially more conductive than the CNF composite. The CNT and CNF composites were irradiated with electrons and neutrons to fluence levels of and. No changes were observed in the resistivity of the CNF composites following neutron and electron irradiation. A 3.7% increase in resistivity was observed …

Radiation Effects On The Electrical Properties Of Hafnium Oxide Based Mos Capacitors, Jesse C. Foster

Theses and Dissertations

Hafnium oxide-based MOS capacitors were investigated to determine electrical property response to radiation environments. In situ capacitance versus voltage measurements were analyzed to identify voltage shifting as a result of changes to trapped charge with increasing dose of gamma, neutron, and ion radiation. In situ measurements required investigation and optimization of capacitor fabrication to include dicing, cleaning, metalization, packaging, and wire bonding. A top metal contact of 200 angstroms of titanium followed by 2800 angstroms of gold allowed for repeatable wire bonding and proper electrical response. Gamma and ion irradiations of atomic layer deposited hafnium oxide on silicon devices both …

Characterization Of The Neutron Spectrum At The Indiana University Nrep Neutron Source, Matthew R. Halstead

Theses and Dissertations

The neutron source at the Indiana University Cyclotron Facility produces neutrons via proton bombardment of a natural beryllium (100% 9Be) target. This source has two beam lines: the LENS and the NREP. The energy spectrum of the neutrons produced on the NREP beam line has not yet been characterized. Through simulation using the GEANT and MCNP particle transport codes as well as neutron activation analysis experiments, an attempt was made to characterize the energy spectrum of the neutron production source. First, the neutron production spectrum of beryllium, simulated using GEANT, was compared with literature; there are significant deviations. Next, foils …

Directional Pair-Production Spectrometer Design For Airborne Stand-Off Detection Of Special Nuclear Material, William L. Harrell

Theses and Dissertations

The purposes of this research are to experimentally and theoretically prove the concept of a directional pair-production spectrometer to detect and locate the tailings that are created when making Special Nuclear Material (SNM) at stand-off distances from a remotely piloted vehicle (RPV). A directional pair-production spectrometer uses the information garnered from the high energy gamma rays emitted by these SNM manufacturing tailings to perform pair-production spectroscopy and identify the isotope of interest. Through simultaneous operation as a Compton camera, the detection system will be able to measure rudimentary directional information from the medium energy gamma decays. The detector used for …

Tof-Sims For Rapid Nuclear Forensics Evaluation Of Uranium Oxide Particles, Hannah E. Hocking

Theses and Dissertations

Because of nuclear proliferation concerns, nuclear material must be safeguarded, and peaceful intentions verified. The field of nuclear forensics addresses these concerns. While established nuclear forensic techniques exist, quicker, more accurate and less expensive methods are of interest for nonproliferation applications. Currently a host of different analytical techniques, requiring a week or longer, are employed to obtain isotopic ratios, chemical abundances and morphology for forensic particulate samples. Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS) is a candidate technology for rapid evaluation of these properties for small amounts of nuclear materials. After a thorough investigation, this study found TOF-SIMS to be particularly …

Characterization Of Neutron-Induced Defects In Isotopically Enriched Lithium Tetraborate, Brant E. Kananen

Theses and Dissertations

Lithium Tetraborate (LTB) is assessed for use as a material for neutron detection. LTB isotopically enriched in either Li-6 or B-10 provides a medium that efficiently captures and transmutes neutrons into more readily detected forms of material or energy. Neutron detection is desirable to detect elicit movement of special nuclear material or nuclear weapons. Single crystals of LTB, Li-6 or B-10 enriched, were neutron irradiated, and electron paramagnetic resonance was used to detect point defects induced by the neutrons. Multiple defects were noted in the irradiated crystals. Two particular defects, perturbed lithium vacancies and lithium clusters are proposed as induced …

A Comparison In The Accuracy Of Mapping Nuclear Fallout Patterns Using Hpac, Hysplit, Delfic Fpt And An Afit Fortran95 Fallout Deposition Code, April D. Miller

Theses and Dissertations

Four nuclear fallout mapping tools are studied to determine which tool predicts the most accurate fallout dose-rate contours with low computation time and resources. The four programs consist of the FORTRAN95 based Fallout Deposition Code (FDC), the Hazard Prediction and Assessment Capability's (HPAC) Nuclear Weapon (NWPN), the Defense Land Fallout Interpretative Code (DELFIC) Fallout Planning Tool (FPT) and the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) Model. The models were compared to the Defense Nuclear Agency's (DNA) DNA 1251-1-EX, Compilation of Local Fallout Data from Test Detonations 1945-1962 Extracted from DASA 1251, using Warner and Platt's Measure of Effectiveness (MOE) method. …

Nuclear Weapon Yield Determination Through Nano Indentation Of Thermally Degraded Automobile Paint, Michael J. Richards

Theses and Dissertations

This work investigated the suitability of automotive clearcoat as a nuclear weapon yield sensor, using the change in elastic modulus as the primary metric. The AFIT Xenon Thermal Simulator (AXTS) was used to simulate a nuclear thermal pulse. The elastic modulus of the clearcoat was measured using a nano indenter. During this research the power density of the AXTS beam was increased from 44.7 to 63.7 W/cm². The morphological steps through which automobile paint proceeds as it thermally degrades were identified and correlated with temperatures. A computer model was created and used to ensure that the paint’s time-temperature …

Positron Annihilation Ratio Spectroscopy Study Of Electric Fields Applied To Positronium At Material Interfaces, Ariella C. Walker

Theses and Dissertations

The purpose of this research was to develop a new code to analyze the data from AFIT's positron annihilation of radiation spectrometer, PsARS, system. The PsARS was used to analyze positronium formation at the surface of a capillary tube coated with gold. Using energy and geometry filters, the PsARS code determined the ratio of ortho-positronium to para-positronium. An electric field applied across the capillary tube wall forced positrons to move towards the gold surface of the capillary tube and prevent them from dropping into the Ore gap before they reach the surface. Inside the Ore gap, the positrons are more …

Investigation Of Gate Leakage Current In Nitrogen-Irradiated Algan/Gan Heterostructures, Rose E. May

Theses and Dissertations

Due to commercial and government interest in devices capable of functioning in high-power, high-frequency space applications, radiation tolerant AlGaN/GaN devices have been under study in recent years. Passivation of the AlGaN surface by (Si₃N₄) prevents electron trapping and enhances the 2DEG, but it also increases gate leakage currents, which can lead to device failure. This study sought information about current leakage mechanisms by introducing displacement damage close to the Si₃N₄/AlGaN interface. The effects of irradiation damage around the Si₃N₄/AlGaN interface on irradiation-induced leakage current were investigated for three …

Coherent Photoproduction Of Π+ From 3he, R. Nasseripour, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We have measured the differential cross section for the γ³He→ π⁺t reaction. This reaction was studied using the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid ³He target. The differential cross sections for the γ³He→ π⁺t reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at backward angles, …

Centrality Dependence Of Two-Particle Number And Transverse Momentum Correlations In 200 Gev Au+Au Collisions At Rhic, Laurence Henry Tarini

Wayne State University Dissertations

We present plots of the pattern of particle formation in $sqrt{s_{NN}}=200$ GeV Au+Au heavy ion collisions at the Relativistic Heavy Ion Collider (RHIC) using three different two-particle correlation measurements of number and transverse momentum as a function of relative azimuth, pseudorapidity and centrality. All three observables show the onset of a ``ridge" feature of enhanced correlations in pseudorapidity with increasing centrality. The plots of real data are compared to plots of simulations using RQMD data and data from a simple ``cluster'' model. The intent of the analysis is to analyze the role of radial flow in the onset of the …

Proton-Proton Correlation Functions As A Probe To Reaction, Micha A. Kilburn '95

Doctoral Dissertations

In an experiment at NSCL, proton-proton (p-p) correlation functions were measured in ⁴⁰Ca+⁴⁰Ca and ⁴⁸Ca+⁴⁸Ca reactions, both at E/A = 80 MeV. The High Resolution Array (HiRA) detected light particles with excellent energy (<200 keV) and angular (~0.2^o) resolution. The MSU 4pi Array covered 77% of the total 4pi solid angle and was used to determine the impact parameter for collisions using transverse energy (E_t) as the relevant observable.

Two-particle correlation functions are employed in this work to measure the space-time …

Analysis Of Electrodeposited Nickel-Iron Alloy Film Composition Using Particle-Induced X-Ray Emission, Alyssa Frey, Nicholas Wozniak, Timothy Nagi, Matthew Keller, J. Mark Lunderberg, Graham F. Peaslee, Paul Deyoung, Jennifer R. Hampton

Faculty Publications

The elemental composition of electrodeposited NiFe thin films was analyzed with particle-induced X-ray emission (PIXE). The thin films were electrodeposited on polycrystalline Au substrates from a 100mM NiSO₄, 10 mM FeSO₄, 0.5M H₃BO₃, and 1M Na₂SO₄ solution. PIXE spectra of these films were analyzed to obtain relative amounts of Ni and Fe as a function of deposition potential and deposition time. The results show that PIXE can measure the total deposited metal in a sample over at least four orders of magnitude with similar fractional uncertainties. The technique is …

Long-Lived Neutral Hadrons In The Calorimeter Of The Zeus Detector., Faridah Mohamad Idris

Student Works (2010-2019)

During the electron-proton collision at HERA, the long-lived neutral hadrons in their final states may travel from the centre of the ZEUS detector to reach the calorimeter and deposit its energy in the calorimeter as islands of energies. The neutral hadrons travel in straight path and were not deflected by the magnetic field in the ZEUS detector. In this thesis, measurements of the long-lived neutral hadrons 0 L K and neutron in the final states in the calorimeter of the ZEUS detector has been carried out using the energy deposited by ZEUS Unidentified Flow Objects (ZUFOs) that were not associated …

Anisotropic Response Of Nanosized Bismuth Films Upon Femtosecond Laser Excitation Monitored By Ultrafast Electron Diffraction, Ahmed R. Esmail, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

The lattice response of 5 nm thick bismuth film to femtosecond laser excitation is probed by ultrafast electron diffraction. The transient decay time after laser excitation is greater for diffraction from (012) lattice planes compared to (110) planes and is reduced for both planes with the increased laser fluence. These results indicate that different energy coupling mechanisms to the lattice occur depending on the crystal direction. The behavior of the diffraction peak width indicates partial disorder of the film upon photoexcitation that increases together with the laser fluence. © 2011 American Institute of Physics. [doi:10.1063/1.3652919]

Photoproduction Of The Φ(1020) Meson In Neutral Decay Mode Γp → Φp → K(S)K(L)P, Heghine Seraydaryan

Physics Theses & Dissertations

The Φ(1020) meson photoproduction cross sections in the neutral decay mode Φ → K_SK_L are measured for the first time. This work presents measurements of differential cross sections, dσ/dt, dσ/d cos θ^Φ_c.m.; Φ decay angular distributions, W(cos θ) and W(Φ), and spin-density matrix elements, ρ⁰, in the Helicity and Gottfried-Jackson frames, in the energy range 1.6 GeV < E_γ < 2.6 GeV. We analyzed the photoproduction data of the g11a experiment collected on an LH2 target using the CLAS detectector at Hall B, TJNAF. The measured cross sections show some differences from the charged decay mode Φ → K⁺ K⁻.