Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session G12: Undergraduate Research IVUndergraduate
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Chair: Brad Conrad, Society of Physics Students/Sigma Pi Sigma Room: Sheraton Plaza Court 1 |
Sunday, April 14, 2019 8:30AM - 8:42AM |
G12.00001: Sounds of Discovery, Creating an Exhibit for the NBLA Kristen Larson The newest exhibit addition to the Niels Bohr Library and Archives, Sounds of Discovery, highlights the works of Frederick Hunt, Robert Shankland and Marie Tharp. The common thread through their varying research was using acoustics to make discoveries or advance current technologies of the period. This exhibit features sound waves as presented in architectural acoustics, sonar development throughout WWII, and ocean floor mapping. By using the oral histories from the archival collections and a few books to shape the historical side, a supplementary element of current/on-going research is provided for those interested in seeing how events have progressed through time. My work has involved the research and gathering of materials to present as well as creating physical representations of the subject matter. Given that sound is inherently heard and not seen this presented an intriguing dynamic in shaping how to display an exhibit in a visual context. By reflecting on the three most common learning styles: visual, auditory and kinesthetic, elements were added to the design process to enhance the learning of the topic for viewers within a limited scope. These fundamental factors proved to create an ambitious yet successful exhibit. |
Sunday, April 14, 2019 8:42AM - 8:54AM |
G12.00002: What can elves tell us about very strong lightning? William Daniels, Kevin-Druis Merenda, Lawrence Wiencke Elves are a class of transient luminous events that occur in the ionosphere above strong lightning strikes. This phenomenon is intricately linked to the process of lightning formation. Each lightning strike creates a unique electromagnetic pulse (EMP) that propagates outwards to the ionosphere. Once there, the EMP accelerates free electrons that cause nitrogen molecules to fluoresce. The fluorescence detectors at the Pierre Auger Cosmic Ray Observatory are quite sensitive to this signature, which constitutes an elve. Using the elves, we might be able to reconstruct the lightning parameters that created them. This would give us insight into the inner mechanisms of some of the strongest and least understood storms on the planet. To begin to study this relationship, we used simulation to estimate the effect of lightning parameters on the shape and magnitude of elve time profiles. Mapping the parameter space of the simulation in this way will give us a test bed to better extract information about lightning from the elves. Furthermore, it will allow us to correlate our simulated results with elve data collected at Pierre Auger. |
Sunday, April 14, 2019 8:54AM - 9:06AM |
G12.00003: Neutralino-Induced Electron-Positron Pair Production in Strong Magnetic Fields Sarah Nicholson, Todd M. Tinsley Our understanding of dark matter comes exclusively through its gravitational effects on normal matter, but other possibilities of study hinge on whether it can also couple to normal matter through the weak interaction. In this work, I consider whether strong magnetic fields could enhance a possible weak interaction between dark matter and electrons and positrons. While dark matter cannot directly couple to magnetic fields, it has been shown that the decays and cross sections of neutral particles can be affected by magnetic fields when there are charged particles in the final state. Furthermore, dark matter accumulates in gravity wells, including the centers of stars where there can exist strong magnetic fields. The goal of this research is to determine if a magnetic field can stimulate dark matter to radiate away an electron-positron pair. I consider as my dark matter candidate the lightest neutralino from the minimally supersymmetric extension of the Standard Model because of its stability, mass, and weak coupling with normal matter. In this talk, I will present the details of this calculation and consider whether this process provides a possible detection signature. |
Sunday, April 14, 2019 9:06AM - 9:18AM |
G12.00004: ABSTRACT WITHDRAWN
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Sunday, April 14, 2019 9:18AM - 9:30AM |
G12.00005: Electron Spin Resonance of Magnetic Two-Dimensional Covalent Organic Frameworks Abigail A. Firme, Valerie A. Kuehl, Joseph R. Murphy, John O. Hoberg, William D. Rice Two-dimensional (2D) materials have generated significant interest because of their unique electrical, optical, and magnetic single-layer behaviors. However, the inability to add electrical or magnetic dopants to a substantial set of 2D materials hinders their ability to be incorporated into device architectures. Here, we synthesize 2D covalent organic frameworks (COFs) that have a lattice of nanopores, which we are able to synthetically fill with magnetic ions (Mn2+) that are hexagonally arranged. We use a host of characterization techniques, such as x-ray diffraction, TEM, NMR, and FTIR, to demonstrate that our COFs are ordered, nanoporous, and 2D. Magnetic ion incorporation is empirically shown through electron spin resonance measurements. Unlike the unfilled COFs, which have a single peak at g=2.0, the Mn-filled COFs show a hyperfine-split, sextet of peaks with a spin relaxation time of ~5 ns and a 19 G exchange splitting. The ability to chemically change the nanopore spacing and the inter-ion distance, combined with our confirmation of the hexagonal Mn2+ ion arrangement, suggests the possibility of using these 2D COFs for potential quantum spin liquids or in magneto-optical devices. |
Sunday, April 14, 2019 9:30AM - 9:42AM |
G12.00006: Measuring Infrared Emission from InSb Quantum Dots Ethan J Taylor, Theodore John Kraus, Bruce Alan Parkinson, William Rice Small bandgap semiconductors, such as PbS, PbSe, and InSb, that are optically sensitive to near- and mid-infrared (IR) light can be used to increase the wavelength solar spectrum sensitivity of modern, multipartite photovoltaics. As with other semiconducting materials, small bandgap semiconductors can be formed into quantum dots or colloidal nanocrystals, thus enhancing both their absorptive cross-sections and emission efficiencies, which are crucial optoelectronic parameters. Critically, the large exciton radii of many small bandgap semiconductors allows researchers to control the semiconducting bandgap by altering the quantum dot diameter around or below the exciton radius (~10 to 20 nm). Here, we discuss the design and construction of a setup to detect mid-IR (1.5 to 6 mm) photoluminescence (PL) using a tunable, visible excitation source. Using this system, we measure PL from 15 nm-diameter InSb quantum dots produced using Sn-seeded growth and atomic layer deposition. We find that the PL from these quantum dots is centered between 2 to 3 mm confirming their high crystallinity and TEM-determined average ensemble diameter. In addition to these results, future measurements using high-intensity visible and near-IR excitation will be discussed. |
Sunday, April 14, 2019 9:42AM - 9:54AM |
G12.00007: ABSTRACT WITHDRAWN
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