Physical Sciences and Mathematics 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 …

Compact Wakefield Accelerator With Advanced Beam Manipulations, Wei Hou Tan

Graduate Research Theses & Dissertations

Beam-driven structure wakefield acceleration is an advanced accelerator concept proposedto develop accelerators with much smaller footprints than conventional state-of-the-art accelerators at a similar energy scale. The concept relies on the generation of electromagnetics wakefields through the interaction of a highly charged “drive” beam with a structure, such as a waveguide, to accelerate a following bright “witness” beam with produced wakefields. This dissertation discusses three aspects critical to structure-wakefield accelerators: the manipulation of the drive beam for efficient wakefield acceleration, the development of a photoinjector capable of producing bright witness electron beams, and the investigation of beam instability in a wakefield …

Magnetic Charge Ordering Of Pinwheel Artificial Spin Ice In In-Plane External Magnetic Fields And Its Application For Tunable Vortex Pinning, Timothy Draher

Graduate Research Theses & Dissertations

Pinwheel artificial spin ice (ASI) systems fabricated using permalloy nanobars offer tunable control of superconducting vortices in an ASI-superconductor hybrid. Vortex pinningis achieved by tuning the ordering of the ASI’s magnetic charge distribution via an external field to create an optimal potential energy landscape to which superconducting vortex motion can be impeded or pinned. Magnetic charge ordering in a pinwheel ASI is visualized using MuMax3 micromagnetic simulations to aid in characterizing the correlation of charge ordering amongst the spin ice system with the application of the external field. Vortex pinning is characterized in a sample of pinwheel spin ice patterned …

Search For Charged Higgs Bosons In The Tau+Nu Final State With 139 Inverse Fb Of Pp Collision Data At Sqrt(S)=13 Tev With The Atlas Experiment, Elliot Wesley Parrish

Graduate Research Theses & Dissertations

This dissertation uses 139 inverse fb of pp collision data collected at a center of mass energy of sqrt(s)=13 TeV by the ATLAS detector to search for charged Higgs bosons decaying to a tau lepton and a neutrino in association with a top quark. Two subchannels are defined based on the leptonic decay (tau+lepton) or hadronic decay (tau+jets) of the associated top quark. Parameterized Neural Networks are investigated and optimized to improve signal separation from background in both subchannels across a wide charged Higgs boson mass range of 80 GeV to 3000 GeV. Expected exclusion limits at 95% confidence on …

Studies Of Vector Boson Scattering In The Semileptonic Zv Channel With The Cms Detector At √S = 13 Tev, Ramanpreet Singh

Graduate Research Theses & Dissertations

This dissertation reports on the search for the vector boson scattering (VBS) in semileptonicZV channel, where the Z boson decays to a pair of leptons (electrons or muons), and the other vector boson V (either W or Z) decays hadronically to a pair of jets, in association of two large pseudorapidity jets i.e. ZVjj → l+l−jjjj, l = e or μ. The search used 137 fb−1 of proton-proton collision data collected by the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider (LHC) with center-of-mass energy (√s) of 13 TeV from 2016 to 2018. VBS is a key process …

Precise Phase Space Control For Future Linear Colliders, Tianzhe Xu

Graduate Research Theses & Dissertations

The design of future linear colliders is highly constrained by their cost and footprint. Phase space partitioning offers an attractive path towards cost and complexity reduction through precise tailoring of particle beam distributions. In this dissertation, we discuss a phase space manipulation technique for generating flat electron beams---a type of beam distribution of particular interest to linear colliders. We report the experimental generation of flat beams with transverse-emittance ratio up to 200 at Argonne Wakefield Accelerator facility. We further expand the technique by combining it with transverse-to-longitudinal emittance exchange. We present the conceptual design of an electron injector capable of …

Third-Integer Resonant Extraction Regulation System For Mu2e, Aakaash Narayanan

Graduate Research Theses & Dissertations

A third-integer resonant slow extraction system is being developed for Fermilab's Delivery Ring to deliver protons to the upcoming Mu2e experiment. The timescale of the extraction (or spill) duration is 43 milliseconds, which is extremely short and unprecedented. Additionally, the experiment's strict and challenging requirements on the quality of the spill at this time scale has led to the development of a new Spill Regulation System (SRS) design. The SRS primarily consists of three components - slow regulation, fast regulation, and harmonic content suppressor. Contributions to the first two components of the SRS, i.e., Slow Regulation and Fast Regulation subsystems, …

Measuring The Diphoton Production From Higgs Boson Decays And In Association With Heavy Flavor Jets, Brianna Lynn Dwyer

Graduate Research Theses & Dissertations

In this dissertation, two important measurements are presented related to diphoton production, the differential cross-section measurement of the Higgs boson in the diphoton decay channel as well as a measurement on inclusive diphoton production with associated heavy-flavor jets. Selections between the two analyses are complimentary, making them a natural pairing in the context of this dissertation. The cross-section measurement is performed in a fiducial region of phase space to closely matches experimental selections. This allows for a largely model-independent measurement, providing a meticulous test of the Standard Model as well as other theoretical predictions. The production of diphoton + heavy-flavor …

An Upgraded Photoinjector For The Argonne Wakefield Accelerator, Emily Frame

Graduate Research Theses & Dissertations

The Argonne Wakefield Accelerator (AWA) is planning an upgrade of the drive-beam accelerator’s photoinjector, the driving force of electron generation. The upgrade’s main goal is to improve beam brightness using linear accelerating cavities and a radiofrequency-gun cavity. In the process of this upgrade, one of the beam focusing solenoids is being redesigned. A beam dynamics optimization is performed for two new solenoid designs, with considerations for producing low-charge (∼ 1 nC) electron bunches as well as operations at higher charges (∼ 50 nC). This project focuses on the optimization study for both the low- and high-charge regimes, exploring the impact …

Modeling Of Sub-Terahertz Wakefield Structures For Electron-Bunch Acceleration, Cassandra Phillips

Graduate Research Theses & Dissertations

Dielectric-lined waveguides have been extensively studied to potentially support high-gradient acceleration in beam-driven dielectric wakefield acceleration (DWFA) and for beam manipulations. In this thesis, we investigate the wakefield generated by a relativistic bunch passing through a dielectric waveguide with different transverse sections. I specifically consider the case of a structure consisting of two dielectric slabs, along with rectangular and square structures. Numerical simulations performed with the fine-difference time-domain WarpX program reveal interesting features of the transverse wake and possible experiments at the Argonne Wakefield Accelerator (AWA) are proposed.

Experimental Exploration Of Shared Magnetic Phases Between Diverse Systems Of Iron-Pnictide Superconductors, Ryan Scott Stadel

Graduate Research Theses & Dissertations

The exciting field of iron-pnictide superconductors offers unique opportunities for studying the relationship between magnetism and unconventional superconductivity. This is vital to developing an understanding of the microscopic origin of high-temperature superconductivity, which is itself an important step in harnessing such a potentially revolutionary technology.

Polycrystalline and crystalline samples are synthesized over a diverse collection of related iron-pnictide systems including (Ca,Sr,Ba)1-xNaxFe2As2, Ba(Fe1-xCox)2As2 (122s), and LaFeAs1-xPxO, and TbFeAs1-xPxO (1111s). These compounds are characterized through various types of neutron and x-ray diffraction on multiple instruments, as well as muon spin resonance, and magnetic susceptibility measurements.

A thorough investigation into the conditions under …

Collisional Methods With Applications To Charged Particle Beams, Afnan Al Marzouk

Graduate Research Theses & Dissertations

Accurate and efficient computational methods are essential to study the dynamics of charged particle beams. Most of the available numerical methods in beam physics are based on the collisionless model which is sufficient for applications that does not depend on Coulomb collisions of the simultaneously interacting particles. However, the development of collisional numerical methods has become greatly important in recent years for applications where collisions play an important role such as the electron cooling of high energy hadron beams. While collisional methods can provide very accurate simulations, their algorithms are very complex, and they face efficiency challenges. In this work, …

Experimental And Numerical Investigation Of Instabilities In A Two-Mirror Fabry-Perot Resonator, Matthew J. Urfer

Graduate Research Theses & Dissertations

Fabry-Perot cavities have a variety of applications in science and industry. Maintaining the stability of a Fabry-Perot cavity is paramount. A Fabry-Perot cavity requires such precision that, if the injected laser pulse is slightly misaligned or the eigenmodes of the cavity are slightly mismatched, the cavity will destabilize from the fundamental mode and begin to exhibit high order modal structure. Depending on their nature, small misalignments will couple to the first order Gaussian modes. This paper discusses the effects of these small misalignments, observed mode structures, as well as computational results from simulations of the optical system.

Beam Phase Space Diagnostic Techniques Along The Fermilab Muon Campus Extraction Line, Benjamin Simons

Graduate Research Theses & Dissertations

The pursuit of physics beyond the Standard Model relies on the ability to make highly sensitive measurements with a high level of precision. Particle accelerators have been a cornerstone for the foundation of tools that have allowed us to continue to probe the limits of what the Standard Model can predict.

This thesis is focused on applying various measurement techniques, some standard and one not so standard, that provide crucial information about beam optics and beam quality for the purposes of monitoring the beam as it is guided throughout a beam transport system. After the measuring techniques have been described, …

Superconducting Cuprates: Synthesis, Characterization And Diffuse Scattering Properties, Bisham Poudel

Graduate Research Theses & Dissertations

Since its discovery more than a century ago, the fascinating phenomenon of superconductivity remains as mysterious as ever with the greatest challenge facing the condensed matter community being the elusive understanding of the microscopic origin leading to its inception. Many outstanding questions remain of which the role played by nematic fluctuations and structural disorder for the stabilization of superconductivity is not well understood. In this respect, superconducting YBa2Cu3O6+x (YBCO)-type cuprates present an ideal framework in which charge doping, structural disorder and various site manipulations can be explored in efforts to address some of these questions. Extensive synthesis and characterization efforts …

Clinical Applications And Feasibility Of Proton Ct And Proton Radiography, Christina Marie Sarosiek

Graduate Research Theses & Dissertations

Proton therapy is a form of radiation treatment for cancer that utilizes the Bragg peak to create conformal high dose regions around the tumor volume. However, the use of x-ray computed tomography (CT) and x-ray radiography for treatment planning and pre-treatment quality assurance procedures improves the achievable effectiveness of proton treatment plans (using proton CT) and the pretreatment verification (using proton radiography). Errors in the conversion from x-ray Hounsfield units (HU) to proton relative stopping powers (RSP) leads to errors in the predicted proton range. To account for the errors, 3.5% margins are included in the treatment plan. This means …

Signal-Background Analysis For New Physics At Particle Colliders And The Criteria For Its Discovery, Prudhvi Nikhil Bhattiprolu

Graduate Research Theses & Dissertations

Although the Standard Model (SM) is now complete with the spectacular discovery of the Higgs boson at the Large Hadron Collider (LHC), there are many unsolved puzzles such as the electroweak hierarchy problem, dark matter, neutrino masses, etc., that need to be addressed. Theories proposed to solve these issues often involve new and exotic particles at the TeV scale and beyond. It is therefore of great importance to devise novel strategies to extract new physics signals with small rates lurking in huge backgrounds. My research detailed here is broadly along those lines.

Vectorlike leptons (VLL) are an intriguing possibility for …