Physical Sciences and Mathematics Commons^™

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 …

Spectral Analysis Of Cyclotron Radiation For Electron Beam Diagnostics, Brendan Leung

Graduate Research Theses & Dissertations

The spectral distribution of the cyclotron radiation emitted by non-ultra-relativistic electrons traveling through solenoidal lenses can be used to characterize ensemble-averaged properties of a beam. In this paper we explore the potential use of cyclotron radiation to measure the energy spread and transverse emittance of a beam while remaining unintrusive. We specifically discuss the relation between the spectral properties of cyclotron radiation and the beam statistical properties and perform first principle particle-in-cell simulation to validate our findings.

Photoinjector Generation Of High-Charge Magnetized Beams For Electron-Cooling Applications, Aaron Thomas Fetterman

Graduate Research Theses & Dissertations

The recently announced Electron-Ion Collider (EIC), to be built at Brookhaven National Laboratory, will collide high-energy ion-beams and electron beams to pursue nuclear physics research on quark-gluon plasma's. The facility performances (luminosity) would be improved if the ion-beam emittance degradation is mitigated via a phase-space-cooling technique. One potential cooling method uses a bright electron beam to cool the ion beams. The cooling rate for this electron-cooling method depends on the transverse emittance of the cooling electron beam and could benefit from using a beam with significant canonical angular momentum dubbed as a magnetized beam.

This research focuses on simulation and …

Tensor Network Approach For Simulation Of Quantum Many-Body Systems, Danylo Lykov

Graduate Research Theses & Dissertations

The simulation of quantum many-body systems and many-body statistical systems presents a challenge for classical computers. Quantum computation, which recently gained significant scientific interest, can provide a potential advantage over classical approaches in this area. While there are multiple methods for the simulation of the physics of many-body quantum systems, most of them scale exponentially with the number of elements. A Tensor Network approach allows to reduce this exponential scaling for some cases and reduces the pre-factor for others. This approach can be used for the simulation of classical statistical physics models, quantum many-body systems, and quantum computers in particular. …

Design And Optimization Of Superconducting Radio-Frequency Electron Sources, Osama Mohsen

Graduate Research Theses & Dissertations

High brightness electron beams are an essential component that drives current and future accelerators and accelerator-based light sources including Free-Electron lasers (FELs), electron cooling experiments, and compact ultrafast electron probe setups (e.g. ultrafast electron diffraction). In FEL, the possible use of a superconducting radiofrequency (SRF) electron gun to support the generation of high-repetition-rate bright-beam can produce copious amounts of radiation over a broad range of the electromagnetic spectrum which can be used in several scientific experiments while in electron probes, the use of SRF gun can enable the generation of high brightness electron beams at high repetition rates, e.g., necessary …