Physics Commons^™

Measurement Of (Alpha, Neutron) Reactions And Development Of Analysis Tools With The Majorana Demonstrator, Tupendra Kumar Oli

Dissertations and Theses

Neutrinoless double-beta decay (0νββ) is a hypothetical nuclear transition which, if observed, would prove that neutrinos are Majorana particles. In addition, the decay rate could provide an effective neutrino mass scale. The decay violates lepton number conservation and could offer a potential path to explain the matter-antimatter asymmetry in the universe via leptogenesis. However, the experimental observation of this decay is very challenging and would require excellent energy resolution of detectors, low background levels, and high exposure. The MAJORANA DEMONSTRATOR experiment searches for this decay in 76Ge using P-type Point Contact (PPC) High Purity Germanium (HPGe) detectors. In addition, the …

Development And Characterization Of Germanium Detectors For Searching Rare-Event Physics, Rajendra Panth

Dissertations and Theses

High-purity germanium (HPGe) detector has an excellent energy resolution and low-energy detection threshold ideal for searching rare-event physics such as dark matter and neutrinoless double beta decay searches. Understanding the electrical contact properties and the Ge detector properties is key to enhancing the use of Ge detectors for a wide range of applications. Amorphous Ge (a-Ge) is one of the passivation materials used to passivate Ge detectors, which also provides the barrier height to the charge injection. Several a-Ge contact Ge detectors were fabricated and tested at the University of South Dakota (USD) and Max-Planck-Institut (MPI) für Physik in Munich …

Pseudocapacitors For Energy Storage, Anuradha Venkataraman

Dissertations and Theses

Fluctuation in the demand for electrical power and the intermittent nature of the supply of energy from renewable sources like solar and wind have made the need for energy storage a dire necessity. Current storage technologies like batteries and supercapacitors fall short either in terms of power output or in their ability to store sufficient energy. Pseudocapacitors combine features of both and offer an alternative to stabilize the power supply. They possess high rates of charge and discharge and are capable of storing much more energy in comparison to a supercapacitor. In the quest for solutions that are economical and …

Confined Mesoscopic Fluid-Like Films Analyzed With Frequency Modulation And Acoustic Detection, Rodolfo Fernandez Rodriguez

Dissertations and Theses

Complete understanding of the physics underlying the changes in viscoelasticity, relaxation time, and phase transitions that mesoscopic fluid-like systems undergo at solid-liquid interfaces or under confinement remains one of the major challenges in condensed matter physics. Moreover, studies of confined mesoscopic fluid films are relevant to technological areas like adhesion, wetting processes and nanotribology.

This thesis addresses the interaction between two sliding solids interfaces separated by a nanometer sized gap, with emphasis on the role of the mesoscopic fluid film trapped between them. For this purpose we integrated two acoustic techniques, recently introduced by our group, into a sub-nanometer precision …

Crystallographic Image Processing With Unambiguous 2d Bravais Lattice Identification On The Basis Of A Geometric Akaike Information Criterion, Taylor Thomas Bilyeu

Dissertations and Theses

Crystallographic image processing (CIP) is a technique first used to aid in the structure determination of periodic organic complexes imaged with a high-resolution transmission electron microscope (TEM). The technique has subsequently been utilized for TEM images of inorganic crystals, scanning TEM images, and even scanning probe microscope (SPM) images of two-dimensional periodic arrays. We have written software specialized for use on such SPM images. A key step in the CIP process requires that an experimental image be classified as one of only 17 possible mathematical plane symmetry groups. The current methods used for making this symmetry determination are not entirely …

Characterization Of Mesoscopic Fluid Films For Applications In Spm Imaging And Fabrication Of Nanostructures On Responsive Materials, Xiaohua Wang

Dissertations and Theses

This dissertation focuses on characterization of the mesoscopic fluid film, testing its behavior in different application scenarios, including its role in near-field scanning probe microscopy imaging, contribution to the phononic mechanism in nanotribology phenomena, utilizing it as a natural environment in the study of carbohydrate-protein interactions, and harnessing it as bridge to transport ions in the fabrication of nanostructures on responsive polymer materials.

Due to their high resolution and versatile applications in a variety of fields, the family of scanning probe microscopy (SPM) has found widespread acceptance as an analytical and fabrication tool. However, the working mechanism of SPM that …

A 30-Year Record Of The Isotopic Composition Of Atmospheric Methane, Doaa Galal Mohammed Teama

Dissertations and Theses

Methane (CH₄) is one of the most important greenhouse gases after water vapor and carbon dioxide due to its high concentration and global warming potential 25 times than that of CO₂ (based on a 100 year time horizon). Its atmospheric concentration has more than doubled from the preindustrial era due to anthropogenic activities such as rice cultivation, biomass burning, and fossil fuel production. However, the rate of increase of atmospheric CH₄ (or the growth rate) slowed from 1980 until present. The main reason for this trend is a slowdown in the trend of CH₄ sources. …