Physics Commons^™

Coulomb Blockade-Mediated Field Emission Sources Using Ultra-Nanocrystalline Diamond, Jevin Jensen

Graduate Research Theses & Dissertations

Coulomb Blockade effects in field emission provide interesting means of achieving brighter electron sources for numerous applications, ranging from vacuum electronics to the next generation of electron beam technology. Microelectronics cleanroom methods are presented in this thesis for production of field emission sources moderated by the Coulomb Blockade. The use of common processes is an essential step toward widespread experimentation with Coulomb Blockade-mediated field emission apparatuses. The main feature to be explored is the use of nano-diamond films for their potential applicability for this desired outcome. Ultra-Nanocrystalline Diamond is used in two different ways to achieve this, both as a …

Design And Cold Test Of A Metamaterial Accelerating Structure For Two-Beam Acceleration, Dillon Christopher Merenich

Graduate Research Theses & Dissertations

Structure-based wakefield acceleration (SWFA) is an advanced accelerator concept that can achieve higher accelerating gradients than conventional accelerators. Advanced structures are required for SWFA, with metamaterial (MTM) structures as a promising candidate. MTMs are periodic sub-wavelength structures engineered to exhibit exotic electromagnetic properties, such as simultaneously negative permittivity and permeability. Because of their unique electromagnetic properties, MTMs are particularly interesting to SWFA. Previous studies at the Argonne Wakefield Accelerator have demonstrated efficient wakefield power extraction using MTM structures. This thesis presents the design, fabrication, and cold test of an X-band MTM accelerating structure for two-beam acceleration. An MTM structure was …

Systematic Study Of Projection Biases In Weak Lensing Analysis, Prudhvi Raj Varma Chintalapati

Graduate Research Theses & Dissertations

The nature of Dark Energy is possibly one of the most fundamental questions in Physicstoday. Comprising 70% of the energy density of the Universe, and being responsible for the accelerated expansion of the Universe, this mysterious form of energy with negative pressure is challenging our current understanding of the fundamental laws of nature. Cosmological parameters like total relative matter Density Ωm, the normalization of power spectrum σ8 and their combination S8 = σ8 (Ωm/0.3)**0.5 are used to quantify our understanding of the evolution of the large-scale structure in the Universe and shed light on the accelerated expansion, caused by the …

Alignment And Range Verification In Proton Therapy Using Proton Radiography And Proton Ct, Joseph Piet

Graduate Research Theses & Dissertations

Protons are used in radiation therapy to lower doses to healthy tissues by utilizing their Bragg peak. Protons can be used both in imaging and treatment. One of the uses of protons in imaging we tested is its use to align patients using a single beam's eye proton radiograph (pRad). By using a beam's eye pRad, and comparing the water equivalent thickness (WET) to proton digitally reconstructed radiographs (pDRRs), we show that we can measure the best alignment on six axes, three translational and three rotational. This is done by defining a cost function, chi squared, which quantifies the misalignment …

Using Machine Learning To Search For Vector Boson Scattering At The Cms Detector During Run 2, Mark Mekosh

Graduate Research Theses & Dissertations

This work reports on the use of different machine learning (ML) techniques in the search for vector boson scattering (VBS) events in the semileptonic $WV$ channel. VBS is an important process for studying electroweak symmetry breaking (EWSB), the Higgs mechanism, as well as for probing beyond the standard model physics. Boosted decision trees as well as deep neural networks were trained on Monte Carlo simulation samples and applied to 137 fb$^{-1}$ of proton-proton collision data taken from 2016 to 2018 by the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) with a center of mass energy $\sqrt{s} …

Computational Modeling, Simulation, And Potential Applications Of Optical Stochastic Cooling, Austin J. Dick

Graduate Research Theses & Dissertations

With the rising demand for intense particles beams, much research is being conducted in the area of particle beam cooling. One of these methods, called Stochastic Cooling (SC) (developed at CERN in the 1970's), delivered a feedback method to improve the quality and lifetime of circulating proton beams by reducing their 6D phase-space and has been widely implemented in a number of hadron machines. However, traditional stochastic cooling schemes are limited by the bandwidth of microwave frequency systems. Optical Stochastic Cooling (OSC) is a promising extension of the stochastic cooling beam cooling technique. OSC instead uses optical wavelengths which allows …

Simulations Of Electro-Optically Sampled Arbitrarily Shaped Electron Bunches For Wakefield Acceleratiors, Spencer Joseph Kelham

Graduate Research Theses & Dissertations

The measurement and recording of terahertz (THz) electric fields is of specialinterest to particle-accelerator science, as the electric fields of temporally short rela- tivistic electron bunches have frequency components that extend into the THz range. A single-shot, non-destructive measurement of such fields can be made using THz time-domain spectroscopy and electro-optic sampling. At the Argonne Wakefield Ac- celerator, arbitrary electron-bunch shapes are being explored to enhance the efficiency of advanced wakefield-accelerator schemes. In this report, we develop a framework for numerically modeling an implementation of electro-optical sampling – dubbed phase-diversity electro-optic sampling [1] – and apply the model to understand …

Mechanical Behavior Of Metallic Core-Shell Nanoparticles Under Compressive Loading, Phillip Tomich

Graduate Research Theses & Dissertations

Core/shell metallic nanoparticles have been shown to be a promising material type for additive manufacturing in the aerospace and automotive fields. Within additive manufacturing they will be used to accurately make an array of nanoparticles within the grains of metal matrix composites. This in turn will help to strengthen the material while remaining ductility and light weight. In this study, copper/aluminum core/shell nanoparticles are compressed under [100], [110], [111], and [112] directions to showcase their anisotropic material properties. Models of their individual counterparts were also investigated. There are no previous works showing the deformation mechanisms of copper/aluminum core/shell nanoparticles. Molecular …

The Standard Model Precision Parameters At 200 Gev, Zamiul Alam

Graduate Research Theses & Dissertations

The Standard Model can be defined quantitatively by running parameters in a mass-independent renormalization scheme at a fixed reference scale. We provide a set of simple interpolation formulas that give the fundamental Lagrangian parameters in the MS-bar scheme at a renormalization scale of 200 GeV, safely above the top-quark mass and suitable for matching to candidate new physics models at very high mass scales using renormalization group equations. These interpolation formulas take as inputs the on-shell experimental quantities and use the best available calculations in the pure MS-bar scheme. They also serve as an accounting of the parametric uncertainties for …

A High-Precision Electron Emission Model: Computational Methods For Nanoscale Structures, Alister J. Tencate

Graduate Research Theses & Dissertations

The high-intensity, high-brightness and precision frontiers for charged particle beams are an increasingly important focus for study. Electron microscopy has demonstrated high quality beams from a single nanotip emitter, and cathodes of structured nanoscale arrays show promise as ultracold electron sources. Optimization of the cathode design for precision applications necessitates a detailed treatment of the interplay between the structure geometry, quantum mechanical emission mechanism, and electromagnetic interactions between the emitted electrons and the boundary interface. This dissertation details the numerical tools developed to simulate these processes efficiently with enough fidelity to be accurate even in the ultracold regime.

Conventional simulation …

Examining The Feasibility Of Identifying Tau Neutrino Charged Current Events In The Dune Far Detector, Sarah Choate

Graduate Research Theses & Dissertations

Neutrinos began as theoretical, massless particles, and since their first detection they have continued to be the subject of various experiments. One such experiment is DUNE, which is a long baseline neutrino experiment with the goal of studying neutrino properties, such as neutrino oscillation parameters. In this work, two projects were completed, one dealing with the hardware of DUNE and the other dealing with neutrino simulations. For the hardware project, we designed a quality control method for testing adaptor boards which make up part of the Far Detector circuit boards. This method was completed and prototyped, however was not implemented …

Study Of The Dynamics Of Glasses Using Nuclear Resonance Time Domain Interferometry, Marc Pavlik

Graduate Research Theses & Dissertations

Nuclear resonance time domain interferometry (NR-TDI) is used to study the slow dy- namics of liquids (that do not require M ̈ossbauer isotopes) at atomic and molecular length scales between 1 A to 10 nm and at time scales between 1 ns to 10 μs. This new spectroscopy technique covers a new range of previously unexplored momentum transfers between 1 to 100 nm−1 and energies between 10 peV to 100 neV allowing an investigation into the dynami- cal motion of molecules, liquids, and glasses. The notoriously low count rate from quasielastic scattering experiments makes measurements difficult when using synchrotron x-rays …

Using Machine Learning To Predict Student Outcomes, Saba Fatima

Graduate Research Theses & Dissertations

Predicting students’ performance to identify which students are at risk of receiving aD/Fail/Withdraw (DFW) grade and ensuring their timely graduation is not just desirable but also necessary in most educational entities. In the US, not only is the Science, Technology, Engineering, and Mathematics (STEM) major becoming less popular among students, the graduation rate of STEM students is steadily declining. The lack of STEM graduates in the US is a serious problem that will place this country at a disadvantage as a competitor in international technological advancement. In order to secure its status as a technological leader internationally, the US institutions …

Diffuse Scattering And 3d-∆Pdf Analyses: Order-Disorder Phase Transitions In (Sr1−Xcax)3rh4sn13 And Nano2, Puspa Upreti

Graduate Research Theses & Dissertations

Classification of structural phase transitions as being of the displacive or order-disorder types is usually done based on spectroscopic measurements performed above the transition. Transitions of the displacive type typically occur when soft phonon modes condense upon approaching the phase transition, whereas those of the order-disorder type are characterized by structures in which the atoms are located randomly above the phase transition at T* at the minima of a multiwell potential. In the ordered state, i.e., when T

We have performed single crystal x-ray scattering experiments and three-dimensional pair distribution functions (3D-∆PDF) analyses to understand the nature of phase transitions …