Physical Sciences and Mathematics Commons^™

The Future Of Nuclear Security In Moroccan Territory After The Creation Of The New Moroccan Agency Of Nuclear And Radiological Safety And Security: Opportunities And Challenges, Amal Touarsi, Amina Kharchaf

International Journal of Nuclear Security

Nowadays, a security regime for protecting nuclear and radiological material—providing an intelligent national regulatory institution and establishing national security laws—is necessary in order for a state to ensure security of nuclear and radiological materials used within its borders.

This paper focuses on discussing the opportunities and challenges facing the future of nuclear security after the creation of the new Moroccan Agency of Nuclear and Radiological Safety and Security.

The Future Of Nuclear Security: A Medical Physicist’S Perspective, Katharine E. Thomson

International Journal of Nuclear Security

Planning for the future of nuclear security is a vital and complex task, requiring cooperation and contribution from many disciplines and industries. This diversity of expertise should include the medical sector, which faces many of the same challenges as the nuclear industry: controlling access to dangerous material, creating a strong security culture, cooperating with the wider world and engaging the public.

Medical physicists, of which the author is one, oversee all aspects of small-scale radiation use. This paper discusses three key areas increasingly important to both medical and nuclear uses of radioactive materials: public engagement, prevention of nuclear and radiological …

Assessing And Enhancing Nuclear Safety And Security Culture For Small Facilities That Handle Radioactive Material, Solymosi Máté

International Journal of Nuclear Security

The use of radioactive sources is expanding all over the world and abreast the necessity of the enhancement of its safe and secure application is increasing too. In the nuclear industry, the safety and security are top priorities since decades. They share the same goal, to protect humans from the negative affect of the ionizing radiation. The human component of them is a significant factor and technical solutions can protect us so far and thus the culture for safety and security become a major focus. On the other hand, there are still some contradiction between recommendations and international guidance of …

Measurement Of The Prompt J/Psi Pair Production Cross Section In Pp Collisions At Sqrt(S) = 8 Tev With Cms, Grant Valentine Riley

Doctoral Dissertations

The cross section for the prompt production of J/ψ [J/Psi] meson pairs in proton-proton collisions at √ s[sqrt(s)] = 8 TeV at the LHC from a sample corresponding to an integrated luminosity of 20.2±0.5 fb−1 [inverse femtobarns] has been measured with the CMS detector. It provides unique insight into particle production and proton structure in proton-proton (pp) collisions. The two J/ψ mesons are fully reconstructed in their µ +µ −[mu+ mu-] decay. An acceptance region is defined by the individual J/ψ transverse momentum pT J/ψ [J/Psi pT] and rapidity |y J/ψ| [J/Psi Rapidity]. The total fiducial cross section assuming unpolarized …

Search For The Decays Of 113ba, Yongchi Xiao

Doctoral Dissertations

The search for new alpha-emitters in the region above tin-100 was carried out in Japan Atomic Energy Agency (JAEA) tandem accelerator in Tokai, Japan. This work aimed to discover barium-113 produced via the fusion-evaporation reaction nickel-58(nickel-58,3n)barium-113 and observation through its alpha-decay chain from barium-113 to xenon-109 to tellurium-105 and tin-101. In the proof of principle experiment in March 2014, the alpha-decay chain of xenon-109 was observed with Double-sided Silicon Strip Detector (DSSD) and digital electronics at JAEA Recoil Mass Separator (RMS). The first discovery-oriented barium-113 experiment was carried out in December 2014 searching for its alpha-decay, ground-state to ground-state beta-decay …

From Pyrochlore To The Tripod Kagome Lattice: Magnetism Of New Compound Family A2re3sb3o14 (A = Mg, Zn; Re = Pr, Nd, Gd, Tb, Dy, Ho, Er, Yb), Zhiling Dun

Doctoral Dissertations

Geometrical frustration refers to the inability of a complex system to satisfy all its competing interactions within an underlying topological constrained lattice. The two-dimensional kagome lattice is one of the most frustrated lattices and has been a favorite in the theoretical condensed matter community. However, the large variety of exotic states predicted in kagome lattices lies in contrast to a paucity of experimental systems, making new kagome lattice compounds highly desired.

In this dissertation, I shall provide a systematic study of the structural and magnetic properties of a new compounds family, A2RE3Sb3O14 (A = Mg, Zn; RE = Pr, Nd, …

Transport Of Water And Ions Through Single-Walled Armchair Carbon Nanotubes: A Molecular Dynamics Study, Michelle Patricia Aranha

Doctoral Dissertations

The narrow hydrophobic interior of a carbon nanotube (CNT) poses a barrier to the transport of water and ions, and yet, unexpectedly, numerous experimental and simulation studies have confirmed fast water transport rates comparable to those seen in biological aquaporin channels. These outstanding features of high water permeability and high solute rejection of even dissolved ions that would typically require a lot of energy for separation in commercial processes makes carbon nanotubes an exciting candidate for desalination membranes. Extending ion exclusion beyond simple mechanical sieving by the inclusion of electrostatics via added functionality to the nanotube bears promise to not …

Analysis Of Primary Stripper Foils At The Spallation Neutron Source By An Electron Beam Foil Test Stand, Eric Paul Barrowclough

Doctoral Dissertations

Diamond films are used at the Spallation Neutron Source (SNS) as the primary charge exchange foils (i.e., stripper foils) of the accelerated 1 GeV (Gigaelectron volts) hydride ions. The most common type of film used is a nanocrystalline diamond film, typically 17 mm x 45 mm (millimeter) with an aerial density of 350 μg/cm² (microgram per square centimeter). The diamond film is deposited on a corrugated silicon substrate using plasma-assisted chemical vapor deposition. After the growth of the diamond film, 30 mm of the silicon substrate is etched away, leaving a freestanding diamond foil with a silicon handle that …

Exploration Of Equal Tune Transverse Coupling In The Spallation Neutron Source Accumulator Ring, Robert Edward Potts Iii

Doctoral Dissertations

The development of hadron machines is one of the main areas of focus in accelerator technology and is specifically called out as a priority in the high energy physics 10-year plan[70]. The trend for future accelerators is to move towards very high-intensity high-power accelerators to be used as proton drivers for secondary particles, target stations, and high-energy accelerators. These accelerators require lower beam losses and more stringent beam controls to maintain typical loss levels and meet specific final beam distributions.

This study focuses on the recently documented coupling resonance in the Spallation Neutron Source (SNS) accumulator ring. It was previously …

Numerical Studies Of Iron Based Superconductors Using Spin-Fermion Models, Christopher Brian Bishop

Doctoral Dissertations

The iron pnictide and iron chalchogenide superconductors are studied numerically using classical Monte Carlo techniques to reproduce experimental data and make predictions about the nature of the relevant interactions. The focus will be using Spin-Fermion models in a classical approximation to explore the phase diagram and calculate important physical properties of these materials over a wide range of temperatures.

Phase Transitions And The Casimir Effect In Neutron Stars, William Patrick Moffitt

Masters Theses

What lies at the core of a neutron star is still a highly debated topic, with both the composition and the physical interactions in question. In this thesis, we made assumptions regarding the composition to further study the interactions of matter during the transition phases. These phases, also known as nuclear pasta, come from the unique physical conditions which occur within neutron stars. We examine the feasibility of the Casimir effect manifesting during these phases, as well as the effects it would have on the total energy of the system. We find that the crust-core transition cannot support the proper …

Solar System Battery Backups For Reactor Coolant Pumps During Electricity Outages Resulting From Natural Disasters, Md. Shamsul Huda Sohel

International Journal of Nuclear Security

In a nuclear power plant, its coolant system is major safety equipment. Coolant system failure causes several accidents in nuclear history. There are so many causes for coolant system failure. One of them is lack of electric power for coolant pumps. In typically NPP there is backup system for power redundancy. In this article, focus on reactor coolant system and its backup power when main grid lines failure. Here discuss about solar backup power for batteries and increases a safety lines for reactor coolant pumps. So, our main goal is providing a battery backup from reliable natural source and ensuring …

Aligning Technology, Policy And Culture To Enhance Nuclear Security: A Comparative Analysis Of Nigeria And The U.S., Stephen Olumuyiwa Ariyo Dahunsi, John D. Auxier Ii, Joseph Ruric Stainback Iv, Howard Lewis Hall

International Journal of Nuclear Security

Around the world, current energy and climate change concerns have led to more nations adopting nuclear technology as an option for electricity generation. However, one of the challenges to the peaceful application of this technology is the possibility that it will be misused, or that terrorists with global reach may acquire nuclear materials. Nigeria is one country that has embraced the technology to solve its energy challenges, but the country is now faced with an upsurge in terrorism and uprisings staged by various ethnic groups. In addition, corruption is continually becoming a hindrance to national development. These challenges are critical …

Toward A Non-Nuclear World: The Npt Regime – Nuclear Disarmament And The Challenge Of A Wmdfz In The Middle East, Sameh Aboul-Enein

International Journal of Nuclear Security

This paper aims to provide a comprehensive overview of various approaches for nuclear disarmament and nonproliferation with the intention of determining how best to promote a Weapons of Mass Destruction Free Zone in the Middle East (MEWMDFZ). Using a qualitative approach, I investigate historical cases of agreements regarding nonproliferation zones and examine the causes for deadlock through both a perusal of historic successes and failures and a review of relevant literature. Particular focus is given to the failure of the NPT Review Conference of 2015. Furthermore, I discuss the importance of role-play simulations and their indications of the need for …

Local Moments And Itinerant Electrons: Gaining New Insights Through Investigating Electronic And Dynamical Properties, Nicholas Steven Sirica

Doctoral Dissertations

Magnetic materials are often categorized in terms of either a purely local or a purely itinerant picture despite the fact that the vast majority actually fall within a spectrum that ranges between these two extremes. It is from such a starting point that this thesis aims at developing an understanding of how the complex interplay between local moments and itinerant electrons ultimately affects the electronic and dynamical properties. Such ideas are explored in greater detail using two materials as case studies: the chiral helimagnet Cr_1/3NbS₂ [Cr intercalated Niobium Disulfide] and YFe₂Ge₂ [Yttrium Iron Germanide] …

On Laser-Induced Plasma Containing Hydrogen, Ghaneshwar Gautam

Doctoral Dissertations

Laser-induced micro-plasma dynamics are investigated in laboratory air, ultra-high-pure hydrogen gas, and hydrogen-nitrogen gas mixtures. The dissertation focuses on atomic spectroscopy of hydrogen in the visible region.

Line-of-sight measurements are analyzed to obtain spatial distributions of electron densities and excitation temperatures. The studies include evaluation of self-absorption phenomena. The plasma dynamics occur initially well above re-entry speeds and diminish to hypersonic and then supersonic expansions. Expansion velocities are measured that are above three hundred times the speed of sound in standard atmosphere. Optical breakdown is induced by using pulsed laser radiation. Emission spectra are collected by employing a spectrometer equipped …

First-Principles Study Of Point Defect Behavior At Interfaces And In-Plane Strain Fields, Jianqi Xi

Doctoral Dissertations

Interfaces in solid materials are the so-called boundaries, separating crystals with the same structure and chemistry but different orientations, e.g. grain boundaries (GBs), different stacking sequences, e.g. stacking faults (SFs), or crystals with different structures and/or chemistries as well as orientations, e.g. the interface between substrate and thin film. In this study, first-principles calculations are used to investigate the defect behavior at different interfaces and in-plane strain fields, such as stacking fault (SF) in silicon carbide (SiC), in-plane strain field near interfaces in potassium tantalate (KTaO₃), and grain boundary in ceria (CeO₂).

Results show that the …

Total Absorption Spectroscopy Of Neutron Rich Nuclei Across The N=50 Neutron Shell Closure, Kathleen Conner Goetz

Doctoral Dissertations

Decay spectroscopy of neutron rich nuclei near doubly magic 78^Ni [78-Nickel] is relevant to nuclear structure and astrophysics as well as reactor and neutrino physics. β-decay [beta-decay] calorimetry studies are essential to reconstruct the decay strength function and is used to overcome the problems arising from the high density of states leading to nuclear Pandemonium. The Modular Total Absorption Spectrometer, currently located in HRIBF at the Oak Ridge National Laboratory, collected data on 25 fission products of ²³⁸U [238-Uranium] during a run in March 2015. Analysis of the ^84,85,86Br [84, 85 and 86-Bromine] data from the …

Electronic And Magnetic Materials Under External Stimuli, Kenneth Robert O'Neal

Doctoral Dissertations

The interaction between spin, charge, and lattice degrees of freedom leads to exotic and useful properties in multifunctional materials. This delicate balance of energy scales allows external stimuli such as temperature, magnetic field, or pressure to drive to novel phases. As a local probe technique, spectroscopy can provide insight into the microscopic mechanism of the phase transitions. In this dissertation I present spectroscopic studies of functional materials under extreme conditions.

Nanomaterials have attracted attention because nanoscale confinement affects various material properties and often reduces energy scales or suppress phase transitions. Combining Raman and infrared spectroscopies reveals that the breakdown mechanism …

Measurement Of Heavy Flavor Yield And Azimuthal Anisotropy At Forward Angles In Cu + Au Collisions At A Center-Of-Mass Collision Energy Per Nucleon Of 200 Gev, Brandon Kyle Schmoll

Doctoral Dissertations

Heavy flavor quarks are produced early in heavy ion collisions and will experience the full evolution of the Quark Gluon Plasma (QGP). Measurements at forward rapidity may be influenced as much, or more, by the cold nuclear matter effects as by the hot nuclear matter effects associated with a QGP. As the medium evolves, the initial spatial anisotropy of participants is converted to an azimuthal anisotropy in the momentum space of outgoing particles. Therefore, the momentum spectra modification and anisotropy parameters provide useful information about the heavy quark interaction with the bulk medium.

Asymmetric heavy ion collisions, such as Cu+Au, …

Remote Neutron Spectroscopy On Mars, Christopher Gayle Tate

Doctoral Dissertations

Remote neutron spectroscopy is an important technique in planetary science that allows for classification of the amount of light elements in a planetary regolith. It is especially suited for studying hydrogen abundances and elements with high thermal neutron absorption cross sections in the top ~1 meter of regolith. The Mars Science Laboratory rover Curiosity carries the first rover based neutron spectrometer Dynamic Albedo of Neutrons (DAN) in Gale crater, Mars. As the DAN instrument operates in passive mode, it is sensitive to neutrons produced through Galactic Cosmic Ray interactions and neutrons generated by the rover's Multi-Mission Radioisotope Thermoelectric Generator. In …

Jet-Hadron Correlations Relative To The Event Plane Pb--Pb Collisions At The Lhc In Alice, Joel Anthony Mazer

Doctoral Dissertations

In relativistic heavy ion collisions at the Large Hadron Collider (LHC), a hot, dense and strongly interacting medium known as the Quark Gluon Plasma (QGP) is produced. Quarks and gluons from incoming nuclei collide to produce partons at high momenta early in the collisions. By fragmenting into collimated sprays of hadrons, these partons form 'jets'. Within the framework of perturbative Quantum Chromodynamics (pQCD), jet production is well understood in pp collisions. We can use jets measured in pp interactions as a baseline reference for comparing to heavy ion collision systems to detect and study jet quenching. The jet quenching mechanism …

Production Of Electrons From Heavy Flavor Decays In Proton-Lead Collisions Measured With Alice At The Lhc, Rebecca Michelle Scott

Doctoral Dissertations

This dissertation presents a measurement of the yield and cross section of electrons from heavy flavor decays at central rapidity in proton-lead collisions measured by the ALICE (A Large Ion Collider Experiment) detector at the Large Hadron Collider. This analysis extends the transverse momentum reach of an earlier measurement in ALICE and the comparison is shown. The cross section of single electrons in proton-lead collisions is compared to the value expected in the absence of nuclear modification from proton-proton collisions. The cross section is well described by the perturbative Quantum Chromodynamics and no statistically significant alteration due to hot nuclear …

Unveiling Quantum Critical Phenomena In Selected Rare Earth Intermetallic Compounds, Lekhanath Poudel

Doctoral Dissertations

The quantum critical phenomenon of CeCu_6-xAu_x (x =0.1) [gold-doped cerium copper six] presents a host of intriguing puzzles: In particular, the dynamic susceptibility showing E/T-scaling with a fractional exponent of 0.75 is a surprise and is clearly inconsistent with the established approach developed by Hertz, Millis, and Moriya (HMM). Interestingly, the phase diagram of CeCu_6-xAu_x [gold-doped cerium copper six] also suggests a zero temperature structural phase transition, raising the possibility of a structural quantum critical point (QCP). To provide a further insight into the unconventional quantum criticality and to investigate the possibility of …

Properties And Manipulation Of Ionic Liquid-Solid Interfaces In Complex Oxide Materials, Anthony Thomas Wong

Doctoral Dissertations

Ionic liquids are liquid salts that are bringing rapid changes to the field of solid electronic materials. The implementation of ionic liquids in conjunction with these solid materials produces interfacial effects, especially when a bias is applied across the ionic liquid, forming an electric double layer. Electric double layers in ionic liquids are unique in their formation and the interfacial charges that are orders of magnitude higher than conventional techniques they can impart, providing new techniques for device design and implementation. In chapter 1, the fundamentals of the solid state electronic and magnetic materials are introduced, along with ionic liquids, …

Understanding Three-Body Interactions In Hexagonal Close Packed Solid He-4, Ashleigh Locke Barnes

Doctoral Dissertations

The ground state properties of hexagonal close packed (hcp) solid ⁴He [He-4] are dominated by large atomic zero point motions which make the primary contribution to the solid’s low-temperature Debye-Waller (DW) factors. Preliminary investigations have also suggested that three-body interactions can play an important role in this system, particularly at higher densities. However, due to their computational cost, these interactions are not generally incorporated into theoretical models of solid ⁴He [He-4]. In order to accurately treat both zero point motion and three-body interactions, we have developed a perturbative treatment in which the three-body energy is added as a …

Investigating The Properties Of Superfluid He-4 Through Density Functional Calculations, Matthew Francis Dutra

Doctoral Dissertations

We present a study of isotopically pure He-4 systems evaluated using helium density functional theory (He-DFT) with the intent of better understanding their ground state structural and energetic properties, particularly within the scope of singularly-doped helium droplets. We self-consistently solve for the density profiles and chemical potentials for a wide range of pure helium droplet sizes (up to 9500 atoms) via an imaginary time propagation method, and fit the resultant energetic data to a power law formula to be able to extrapolate values for even larger droplets. Subsequent calculations on singularly-doped droplets within the same size range yield accurate binding …

Improving Predictive Capabilities Of Classical Cascade Theory For Nonproliferation Analysis, David Allen Vermillion

Doctoral Dissertations

Uranium enrichment finds a direct and indispensable function in both peaceful and nonpeaceful nuclear applications. Today, over 99% of enriched uranium is produced by gas centrifuge technology. With the international dissemination of the Zippe archetypal design in 1960 followed by the widespread illicit centrifuge trafficking efforts of the A.Q. Khan network, traditional barriers to enrichment technologies are no longer as effective as they once were. Consequently, gas centrifuge technology is now regarded as a high-priority nuclear proliferation threat, and the international nonproliferation community seeks new avenues to effectively and efficiently respond to this emergent threat.

Effective response first requires an …

Experiment And Simulation Of Single-Molecule Recycling, Bo Wang

Doctoral Dissertations

This dissertation presents theoretical, numerical, and experimental research into a technique for extending the observation time of a single molecule in solution, while also enabling measurement of its diffusion coefficient. A confocal microscope is used to observe the fluorescently labelled molecule in aqueous solution, which is confined within a nanochannel. By focusing a laser beam into the nanochannel and applying electrokinetic flow along the tube, a molecule passes through the laser beam and emits a burst of photons. The molecule then passes back and forth through the focus while the voltage is repeatedly reversed at a fixed delay after each …

Characterization Of Reactor Background Radiation At Hfir For The Prospect Experiment, Blaine Alexander Heffron

Masters Theses

This work describes an investigation of the background radiation present at the High Flux Isotope Reactor (HFIR) on behalf of the PROSPECT collaboration. The PROSPECT experiment is designed to make a precision measurement of the antineutrino spectrum at HFIR and search for sterile neutrinos. Temporal and spacial variation of neutron and gamma backgrounds at the experiment site for the PROSPECT detector are measured in order to determine if the reactor correlated radiation will contribute a significant background to the inverse beta decay signal. Knowledge of spacial background variation will also be used to inform the design of a local shield …