Bulletin of the American Physical Society
APS March Meeting 2021
Volume 66, Number 1
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session B37: Undergraduate Research IV: Astro, Particle, and High Energy PhysicsLive Undergrad Friendly
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Sponsoring Units: APS/SPS Chair: Chinedu Ekuma, Lehigh Univ |
Monday, March 15, 2021 11:30AM - 11:42AM Live |
B37.00001: Stream Crossing in Tidal Disruption Events Gauri Batra In a tidal disruption event (TDE), a star approaching a black hole is torn apart by the black hole's tidal force, resulting in the squeezing of the star to form a stream of tidally disrupted material (both bound and unbound). To understand the outcome of TDEs, it is crucial to find where the bound stream intersects itself since intersection can lead to potentially observable shocks, accretion disks and secondary outflows. We compute the intersection regions for a Schwarzschild (non-spinning) black hole and a Kerr (spinning) black hole. We numerically integrate the geodesic equations of motion to find the path of the stream and discuss the algorithm used to find the region of self-intersection. This algorithm takes into account various aspects of the model including stream thickness and energy distribution of the stream material. As a result, we obtain the dependence of the self-intersection region on multiple parameters such as inclination, energy, angular momentum and black hole spin. We also present a novel model for the stream thickness evolution that takes into account general relativistic corrections, and as a result find that shocks do not necessarily happen at the pericenter or the apocenter. |
Monday, March 15, 2021 11:42AM - 11:54AM Live |
B37.00002: Dimensional crossover in non-relativistic effective field theory Silas R Beane, Murtaza Jafry In our project, we consider two-body isotropic scattering with an arbitrary finite-range potential—confined by anisotropic harmonic traps—studied using non-relativistic effective field theory. Compactification from three spatial dimensions to a plane and a line, and from a plane to a line are considered and general relations among effective-range parameters in the various dimensions are obtained, confirming known results and providing several new relations. This is an extension of our previous work which considered toroidal compactification. The implications of this research allow for the calculation of thermodynamic properties of Bosonic gas systems in lower dimensions when only properties of three dimensions can be measured experimentally. Moreover, the calculation will also shed light about the fundamental characteristics and dynamics of an arbitrary low-energy Bose gas system when dimensionally interpolated. |
Monday, March 15, 2021 11:54AM - 12:06PM Live |
B37.00003: Prevalence of Radio Emission in LoBALs Showing Disturbed Morphologies in the Optical Maya Davidson, Mariana Lazarova We present results from an archival investigation using radio data from the Very Large Array Sky Survey (VLASS) of a volume-limited sample of nearby Low-ionization Broad Absorption Line (LoBAL) quasars. They are interesting because of their blue-shifted broad absorption lines in the UV spectra indicating winds. Either radiation fields or radio jets drive these winds and potentially influence the growth of the galaxy, but the driving cause is still debated. Radio jets might drive these extreme outflows in the case of young radio sources with emerging jets. This sample has been previously analyzed in IR and in the optical using the Hubble Space Telescope (HST) to determine the levels of star formation and morphologies. These objects were thought to be radio quiet or intermediate. The radio-to-optical ratio classifies them as radio quiet or radio loud. We investigate the correlation between the optical and the radio morphologies. We create contour maps from the radio data using SAOImage DS9. We overlay the radio contour maps onto the optical images from the HST and investigate any correlations. Preliminary results show a higher fraction of LoBALS having radio emission than is seen in typical quasars, which merits further investigation. |
Monday, March 15, 2021 12:06PM - 12:18PM Live |
B37.00004: Data driven machine learning discovery and exploration of fundamental physical laws Alexander Brady, Trinanjan Datta Machine learning, which is part of artificial intelligence, has become an invaluable tool to manipulate, analyze, predict, and reveal trends and associations hidden within big data. Machine learning algorithms build a mathematical model of sample data in order to make predictions or decisions, whether simply filtering emails and recommending products in a search bar or discovering the fundamental laws governing highly sensitive chaotic systems. In this research investigation we apply the “Least Absolute Shrinkage and Selection Operator” (LASSO) method of data analysis that determines the relationship, or lack thereof, between variables, allowing for the removal of irrelevant features. The method is first applied to a generic system of differential equations, to demonstrate its applicability, before showcasing its application within the context of a chaotic Lorenz oscillator system. The generic coupled system is solved using the LASSO module available in Python’s sci-kit-learn. A similar computational approach for the chaotic system with synthetic Gaussian noisy data successfully reproduces the original Lorenz attractor solution. We also explore the implications of LASSO on data generated from a spin dynamics simulation. |
Monday, March 15, 2021 12:18PM - 12:30PM Live |
B37.00005: Investigation of Neutron Flux resolution and Efficiency of the Neutron Intercepting Silicon Chip (NISC) Peter Hedlesky, Will H Flanagan, John Rabaey, Tim Hossain, Peter Niles, Mark Clopton, Tracy Tipping, Aidan Medcalf, Steven Block, Clayton Fullwood Results from the Neutron Intercepting Silicon Chip’s (NISC) exposure to a thermal neutron beam are presented in this study. The NISC measures neutron flux by taking advantage of B10’s significant cross section (3840 barns) to (0.025eV) neutrons. The B10 interaction with neutrons produces the charged particles Li 3+ and He 2+. These charged particles are produced in the B10 enriched Borosilicate glass (BPSG) that is layered on top of each MOS transistor in the flash chip. This results in the charge particles passing through the memory cell and disrupting the charge in the capacitor. Commonly described as a soft error, these interactions can be qualified as a bit flipping from a “1” to a “0”, or the voltage of the bit’s capacitor decreasing. In interests of measuring the effectiveness of the NISC as a neutron detector, multiple detectors were exposed at UT Austin’s TRIGA MARK II nuclear reactor. The results show that the NISC has significant neutron beam resolution and efficiency over standard gold-foil techniques. |
Monday, March 15, 2021 12:30PM - 12:42PM Live |
B37.00006: Optimal Boron Thickness in a NISC John Rabaey, Steven Block, Will H Flanagan, Clayton Fullwood, Peter Hedlesky, Tim Hossain, Aidan Medcalf, Mark Clopton, Tracy Tipping, Peter Niles A neutron intercepting silicon chip (NISC) comprises a silicon data storage chip coated with a layer of borophosphosilicate glass (BPSG) containing boron-10. Neutrons interact in the boron layer via neutron capture: n + B-10 -> Li-7 + He-4. The ions produced deposit charge (on the order of fC/um) over a range of several microns; when one of them passes through the data-storing oxide-nitride-oxide (ONO) layer of the chip, the charge it deposits causes a leakage across capacitors in the chip, and as a result bits flip from positive to negative. In the interests of optimizing the thickness of the boron layer, a Monte Carlo program has been written to simulate the paths of particles and their charge deposits in the charge-storing layer. The simulation shows that a significant advantage in efficiency can likely be gained by increasing the thickness of the boron layer by an order of magnitude. |
Monday, March 15, 2021 12:42PM - 12:54PM Live |
B37.00007: Constraining the Properties of Kilonovae based on the Zwicky Transient Facility Searches for 13 Neutron Star Mergers. Priyadarshini Rajkumar, Shreya Anand In their third observing run (O3), LIGO and Virgo detected gravitational-wave (GW) candidates from several neutron star-black hole and binary neutron star mergers. The Zwicky Transient Facility (ZTF), an optical time-domain survey telescope, followed-up 13 of these GW events in search of kilonovae (KNe; electromagnetic counterparts to GW events). However, no KNe were found. To assess the implications on potential KN emission based on the upper limits, empirical limits on the KN peak magnitude and evolution rate were determined. One shortcoming of these analyses was the assumption that all peak magnitudes and evolution rates are equally likely. In this work, we present a method to improve upon this assumption by comparing to light curves generated using radiative-transport based KN models, parameterized by ejecta mass and inclination angle. Specifically, we construct priors informed by these KN models to identify regions of parameter space where particular KNe luminosities and evolution rates are improbable. We also factor color evolution into the decay rates, important as observations of GW170817 have shown that photometric behavior of a KN differs in different bands. Finally, we close with an application of this methodology to derive constraints on KN ejecta masses. |
Monday, March 15, 2021 12:54PM - 1:06PM Live |
B37.00008: Electromagnetic Scattering from a Fractal Configuration Christian Rose, Kuloth Shajesh, Jurek Kocik Electromagnetic scattering from a fractal configuration known as Ford Circles is studied. A scattering formalism is presented which leads to an expression for the scattering amplitude of an electromagnetic wave incident upon the fractal. The scattering amplitude is explicitly evaluated as a closed form expression in the dilute dielectric approximation. This expression is shown to be divergent, due to the infinite nature of the circumference of Ford Circles. The scattering amplitude expression in the case of Ford Discs, however, turns out to be finite, due to the finite area associated with the discs. The forward scattering amplitude, taken in the direction of the incident wave, is evaluated for Ford Circles and related to the total scattering cross section using the optical theorem. This leads to a final closed form expression for the scattering cross section from Ford Circles, which verifies that the total scattering cross section remains proportional to the volume of the scatterer even in the case of a fractal scatterer. |
Monday, March 15, 2021 1:06PM - 1:18PM Live |
B37.00009: Doublons in 1D Spin Models Eliana Feifel, Chemda Wiener, Lea Santos In the presence of strong interactions, two particles can bind together forming what became known as doublons. Doublons are a pair of upspins that are either located next to each other, or connected like a ring. They move as a single particle, but slower as the energy levels increase. Doublons have been extensively studied in the Bose-Hubbard model, where the two bosons occupy the same site. We use the Hamiltonian Matrix to help conceputalize quantum systems. We also encorporate the Schrödinger and Dirac equations in order to follow the function of the electron-wave-equation. We focus on spin models, where the doublon corresponds to a bound pair of excitations occupying neighboring sites. We explore different scenarios, where energy conservation would not prevent the bound pair from splitting, such as when an impurity site is added to system, yet the doublons prove to be very robust and stick together. We illustrate our results using a chain of 1/2-spins. |
Monday, March 15, 2021 1:18PM - 1:30PM Live |
B37.00010: Doublons in 2D spin models Chemda Wiener, Eliana Feifel, Lea Santos In the presence of strong interactions, two particles can bind together forming what became known as doublons. They move as a single particle, but slower. Doublons have been extensively studied in the Bose-Hubbard model, where the two bosons occupy the same site. We focus on spin models, where the doublon corresponds to a bound pair of excitations occupying neighboring sites. We explore different scenarios, where energy conservation would allow for different configurations in the plane, even for the splitting of the bound pair, such as when two doublons collide or when an impurity site is added to system, yet the doublons prove to be very robust and stick together. We illustrate our results using two-dimensional spin models. |
Monday, March 15, 2021 1:30PM - 1:42PM Live |
B37.00011: From worldline configurations to properties of hard-core bosons Liana Shpani, Yaghmorassene Hebib, Fabio Lingua, Wei Wang, Barbara Capogrosso-Sansone We present results on hardcore Bose-Hubbard-type models based on perturbation theory, exact diagonalization, and Path-integral Quantum Monte Carlo. We explore the connection between quantum fluctuations and quantum correlations, and geometrical properties of worldline configurations. |
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