Bulletin of the American Physical Society
APS April Meeting 2023
Volume 68, Number 6
Minneapolis, Minnesota (Apr 15-18)
Virtual (Apr 24-26); Time Zone: Central Time
Session B17: Undergraduate Research IIUndergrad Friendly
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Sponsoring Units: SPS Chair: Rex Tayloe, Indiana University Bloomington Room: Marquette VIII - 2nd Floor |
Saturday, April 15, 2023 10:45AM - 10:57AM |
B17.00001: Detector design and electronics for the NAUM (Non-intrusive Archaeometry Using Muons) program Oscar Meza Quintero, Joseph F Sagerer, Avery J Brown, Edmundo J Garcia, Mark R Adams, Arturo Menchaca-Rocha, Austin V Harton The NAUM (Non-intrusive Archaeometry Using Muons) program is a collaboration of US and Mexican institutions building a muon tracker detector for the exploration of El Castillo pyramid in the archaeological zone of Chichen Itza, Mexico. The development of non-intrusive remote sensing techniques has been one of the great interdisciplinary successes of archaeometry. Ground-penetrating radar and electrical resistivity tomography are examples that are mostly used for subsurface explorations. We propose to build imaging capabilities using a complementary technique utilizing the transmission of atmospheric muons through large archaeological buildings. The detector will be able to measure the flow and direction of atmospheric muons under the pyramid. In this talk, we will be describing the project and details of the detector and electronic readout system. |
Saturday, April 15, 2023 10:57AM - 11:09AM |
B17.00002: On site prototype tests and structure modeling for the NAUM (Non-intrusive Archaeometry Using Muons) program Avery J Brown, Joseph Sagerer, Edmundo J Garcia, Oscar Meza Quintero, Austin V Harton, Mark R Adams, Arturo Menchaca-Rocha The NAUM (Non-intrusive Archaeometry Using Muons) program is a collaboration of US and Mexican institutions building a muon tracker detector for the exploration of El Castillo pyramid in the archaeological zone of Chichen Itza, Mexico. The development of non-intrusive remote sensing techniques has been one of the great interdisciplinary successes of archaeometry. Ground-penetrating radar and electrical resistivity tomography are examples that are mostly used for subsurface explorations. We propose to build imaging capabilities using a complementary technique utilizing the transmission of atmospheric muons through large archaeological buildings. The detector will be able to measure the flow and direction of atmospheric muons under the pyramid. In this talk, we will be describing a smaller prototype detector site tests and initial work on modeling and measurements at the Chichen Itza site. This work is partially supported by the National Science Foundation under Grants No. NSF-PHY-2011339, NSF-PHY-2011442. |
Saturday, April 15, 2023 11:09AM - 11:21AM |
B17.00003: Properties of solutions to the mode equations for scalar fields in Schwarzschild-de Sitter spacetime Emily Foley, Paul R Anderson The behaviors of solutions to the mode equations for massless and massive scalar fields with minimal and conformal curvature couplings in Schwarzschild-de Sitter spacetime are investigated. Schwarzschild-de Sitter spacetime is an exact solution to Einstein's equations for a black hole in an expanding universe. It contains both a black hole horizon and a cosmological horizon. The focus will be on the region outside of the cosmological horizon. |
Saturday, April 15, 2023 11:21AM - 11:33AM |
B17.00004: Testing Gravitational Interactions Below 50 Microns Abby Keltz, Kevin Chung, Tanner B Hooven, Emily N Ord, Alexandra Papesh, Claire Rodgers, C.D. Hoyle Attempts to unify the Standard Model and General Relativity often include features that violate the Weak Equivalence Principle (WEP) and/or the gravitational Inverse-Square Law (ISL). A violation of these would question our fundamental understanding of gravity. To further understand nature, undergraduate researchers and faculty at Cal Poly Humboldt are using an experiment to measure gravitational interactions below 50 microns. The experiment uses a torsion pendulum with equal masses of two different materials arranged as a composition dipole. The twist of the torsion pendulum is measured as an attractor mass in a parallel-plate configuration is oscillated nearby. This creates a time dependent torque on the pendulum. The magnitude and size of this torque may provide evidence for deviations in the WEP or ISL at this untested scale. The focus of the experiment at present is to apply adjustments to further isolate experimental results from environmental influences from the surroundings, and to optimize hardware for future data collection. |
Saturday, April 15, 2023 11:33AM - 11:45AM |
B17.00005: Topological Change of Kerr Compact Object Shadows: Properties of Unstable Spherical Photon Orbits Around Kerr Naked Singularities Bao Nguyen, Chi-Kwan Chan, Pierre Christian The Event Horizon Telescope (EHT) recently resolved the supermassive black holes (SMBHs) at the center of M87 (M87*) and the Milky Way (Sgr A*) with the event horizon scale resolution. The geometric features of these observed photon rings have been used to test modified gravity theories and alternative models to SMBHs. Numerous studies have demonstrated that naked singularities, gravitational singularities without event horizons, can also project shadow-like regions. Thus, the EHT observations are still compatible with the possibility of Sgr A* being a naked singularity. This has raised theoretical interests, particularly the weak cosmic censorship hypothesis, which forbids the visibility of singularities for an observer at infinity. In this work, we analytically project the unstable spherical photon orbits around Kerr naked singularities (KNSs) to infinity, which we define to be the "shadow" of KNSs. We demonstrate that this shadow can be close, open, or vanishing, depending on the spins and observational inclination angles, and study the critical parameters where the shadow changes its topology. We then compare these analytical results to numerical ray-tracing simulations. This topological change in the shadow is a new phenomenon for KNS. By using EHT observations, it can be used to test KNSs as alternative models to SMBHs. Besides, we investigate other properties of null geodesics of KNSs that are distinctive from black holes, such as stable photon orbits and regions inside the KNS photon ring. |
Saturday, April 15, 2023 11:45AM - 11:57AM |
B17.00006: Tully Fisher and Radial Accelerations in the Bizyaev et al. 2021 Edge in Galaxies William M Kerin, James G O'Brien, Thomas Chiarelli In this talk we extend the work presented at the last APS meeting using a deeper analysis of the rotation curves of the Bizyaev et al 2021 survey of Ultra Faint Edge on Galaxies. In the previous work, we fit 20 high resolution rotation curves with alternative gravity, namely MOND and Conformal Gravity. The world of rotation curve physics though is much more robust than simply fitting to relevant theories. Here, we expand the work by showing how these galaxies exhibit non Tully Fisher behavior as well as how they still accommodate the Radial Acceleration Rule of McGaugh, Lelli and Schombert (MLS). Discussion and analysis of the ramifications of the behavior found will be discussed and explored, and steps will be shown how this set of galaxies could potentially be used to differentiate the validity of alternative gravitational theories. |
Saturday, April 15, 2023 11:57AM - 12:09PM |
B17.00007: Study of cosmic-ray secondary nuclei and isotopes using GALPROP Zachary M Dorris, Yuca Chen, Eun-Suk Seo Recent high-precision measurements of the isotopic composition of beryllium in cosmic rays provide an unprecedented opportunity to study the structure of the galaxy. Due to decay processes, the ratio of radioactive isotopes to stable isotopes in cosmic rays is sensitive to the escape time of the cosmic rays during propagation. This escape time is related to the scale and physical properties of the galaxy. We examine the energy dependence of secondary cosmic ray elemental spectra and isotopic compositions, with a focus on the isotopes of beryllium. These data are considered in the context of a conventional reacceleration model, using the propagation code GALPROP to compute predicted elemental and isotopic spectra. The implications of the data on transport parameters in this conventional reacceleration model, including constraints on the diffusive halo size, are discussed. |
Saturday, April 15, 2023 12:09PM - 12:21PM |
B17.00008: Study of Cosmic Ray Spectral Features Using GALPROP Yuca Chen, Hongyi Wu, Zachary M Dorris, Eun-Suk Seo Recent space-based and balloon-borne experiments have reported significant spectral hardening of cosmic ray data at around 200 GV. Many different cosmic ray spectra reflect this feature, including primary and secondary elements. To investigate this spectral hardening, the numerical cosmic-ray propagation code GALPROP was used. As a base model, the Plain Diffusion model with reacceleration effects was used. Rigidity-dependent parameters were used to study three cases: (1) a diffusion coefficient break, (2) source spectrum breaks, and (3) a combination of both effects. To explain the positron excess above ~27 GeV, an additional positron source was also investigated. From our prior work in this study, special care was done to account for the low-energy behavior of the B/C ratio and the hydrogen-helium quartet ratios. Elemental spectra and ratios for the three cases will be compared and presented. Plans for improvements will also be discussed. |
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