Physical Sciences and Mathematics Commons^™

Total Absorption Spectroscopy Of Mo-106 And Tc-106, Michael Cooper

Doctoral Dissertations

Total absorption spectroscopy is a method of gamma-ray spectroscopy that has gained prominence in the past several decades, as nuclear data revisions are performed on older nuclear data, which is often incomplete. A strong understanding of underlying nuclear data, particularly fission and beta decay data, is essential for nuclear reactors and nuclear fuel decay heat. This PhD work involves the analysis of fission fragments 106Mo [Mo-106] and 106Tc [Tc-106]. These neutron rich isotopes contribute upwards of 6% of the cumulative fission yield of 241Pu [Pu-241] fission, and 4% of 239Pu [Pu-239] fission. Prior data for these two fission fragments only …

Understanding Liquid Dynamics Using The Van Hove Function From Inelastic Neutron Scattering Measurements, Yadu Krishnan Sarathchandran

Doctoral Dissertations

Liquid state physics remains relatively unexplored compared to solid-state physics, which achieved massive progress over the last century. The theoretical and experimental methodologies used in solid-state physics are not suitable to study the liquid state due to the latter's strong time dependence and the lack of periodicity in structure. The approaches based on phonon dynamics break down when phonons are over-damped and localized in liquids. The microscopic nature of atomic dynamics and many-body interactions leading to liquid state properties such as viscosity and dielectric loss in liquids remain unclear. Inelastic neutron scattering measurements were done to study the microscopic origins …

Measurements Of Fast Alpha Decays In The 100sn Region, Ian Connor Cox

Chancellor’s Honors Program Projects

No abstract provided.

Correction To Luminosity Measurement For The Pixel Luminosity Telescope At Cms, Krishna Thapa

Masters Theses

The search for and detailed study of new particles and forces with the Compact Muon Solenoid (CMS) detector at the Large Hadron Collider (LHC) of CERN is fundamentally dependent on the precise measurement of the rate at which proton-proton collisions produce any particles, the so-called luminosity. Therefore, a new detector, the Pixel Luminosity Telescope (PLT), dedicated to measure the luminosity at high precision was added to the CMS experiment in 2015. It measures the inclusive charged particle production from each collision of proton bunches in the LHC. Additional charged particles which are observed by the instrument but produced from sources …

Fundamental Physics With Cold Neutron Beams, Kyle Brandon Grammer

Doctoral Dissertations

The neutron exhibits rich physics both as a tool for studying materials, particle and nuclear physics, as well as the object of experimental study. The neutron lifetime is an important input to Big Bang Nucleosynthesis models and is currently known only to approximately 0.3\% with the most precise measurements from two different experimental techniques in disagreement by more than 3$\sigma$ [sigma]. Parity violation has been the subject of study since its discovery in 1957. Parity violation experiments provide access to studying the hadronic weak interaction, which is otherwise suppressed by several orders of magnitude below that of the strong interaction. …

Solar Modulation Of The Cosmic Ray Intensity And The Measurement Of The Cerenkov Reemission In Nova’S Liquid Scintillator, Philip James Mason

Doctoral Dissertations

The NOνA (NuMI Off-axis electron neutrino Appearance) experiment is a long baseline neutrino oscillation experiment at Fermi National Accelerator Laboratory. Its purpose is to observe the oscillation of ν_μ (muon neutrino) to ν_e (electron neutrino) and to investigate the neutrino mass hierarchy and CP violation in the neutrino sector. Two detectors have been built for this purpose, a Near Detector 300 feet underground at Fermilab, and a Far Detector, on the surface at Ash River, Minnesota.

The completion of NOνA’s Far Detector in October 2014 enabled not only the recent measurement of neutrino oscillations, but an array of …

Analysis, Prototyping, And Design Of An Ionization Profile Monitor For The Spallation Neutron Source Accumulator Ring, Dirk A. Bartkoski

Doctoral Dissertations

The Spallation Neutron Source (SNS) located in the Oak Ridge National Laboratory is comprised of a 1 GeV linear H^- [H^-] accelerator followed by an accumulator ring that delivers high intensity 1 μs [microsecond] long pulses of 1.5x10¹⁴ [1.5x10^14] protons to a liquid mercury target for neutron production by spallation reaction. With its strict 0.01% total beam loss condition, planned power upgrade, and proposed second target station, SNS ring beam-profile diagnostics capable of monitoring evolving beam conditions during high-power conditions are crucial for efficient operation and improvement. By subjecting ionized electrons created during beam interactions with the residual …

Measurement Of The Prompt Double J/Psi Production Cross Section In Pp Collisions At Sqrt(S) = 7 Tev, Andrew David York

Doctoral Dissertations

The simultaneous production of two J/psi mesons has been significantly observed in proton-proton collisions at a center-of-mass energy of 7 TeV with the CMS detector. The two J/psi mesons are fully reconstructed in their decay to muons. The signal yield is extracted with an extended maximum likelihood fit based on four event variables. A method was developed to correct for detector acceptances and efficiencies based on the measured momenta of the J/psi and their decay muons to maintain the least model dependence possible.

The measurement is performed in an acceptance region defined by the individual J/psi transverse momentum and rapidity. …

Structure And Dynamics Of High Temperature Superconductors, Jennifer Lynn Niedziela

Doctoral Dissertations

High temperature superconductivity in iron based compounds has presented a series of complex problems to condensed matter physics since being discovered in 2008. The stalwart basis of condensed matter physics is the “strength in numbers" aspect of crystalline periodicity. Perfect crystalline periodicity has made possible the reduction of the questions of structural and electronic properties to single dimensions, increasing the tractability of these problems. Nevertheless, modern complex materials stretch these assumptions to their limits, and it is at this point where our work starts. Using neutron and x-ray scattering, we have conducted a series of studies on the structural disorder …

Water Ice Films In Cryogenic Vacuum Chambers, Jesse Michael Labello

Doctoral Dissertations

The space simulation chambers at Arnold Engineering Development Complex (AEDC) allow for the testing and calibration of seeker sensors in cryogenic, high vacuum environments. During operation of these chambers, contaminant films can form on the components in the chamber and disrupt operation. Although these contaminant films can be composed of many molecular species, depending on the species outgassed by warm chamber components and any leaks or virtual leaks (pockets of gas trapped within a vacuum chamber) that may be present, water vapor is most common, and it will be the focus of this dissertation. In this dissertation, some properties of …