Bulletin of the American Physical Society
APS New England Section 2018 Fall Meeting
Volume 63, Number 21
Friday–Saturday, November 2–3, 2018; University of Massachusetts Dartmouth, Dartmouth, Massachusetts
Session B01: Poster Session |
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Room: Library Living Room |
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B01.00001: Identification of Variable Red Dwarf Stars in the ASAS Catalog Seth Gagnon, Kristine Larsen Many stars classified as miscellaneous by an analysis program for the All Sky Automated Survey (ASAS) have actually been misidentified, including red dwarfs known as BY Draconis-type variables. These stars exhibit an irregular periodicity, as well as changes in their mean brightness and amplitude. These irregularities can be attributed to chromospheric activity or spots rotating with the surface of the star. From a list of approximately 1600 “miscellaneous” ASAS stars, possible BY Dra stars, and other well-known types, were identified. This identification is done by analyzing the light curve in the analysis program VStar, made by the AAVSO (American Association of Variable Star Observers), which uses data from the ASAS website to plot a light curve and search for candidate periods. Many of VStar's periodic fits are better than those provided by ASAS, and can be used to reclassify these stars. Since red dwarf stars comprise 90% of the stars in our galaxy they are increasingly the target for exoplanet searches, and the impact of spots and chromospheric behavior on the light curves can complicate such searches. Correcting the classification of red dwarf stars in the AAVSO Variable Star Catalog (VSX) is therefore an important step in understanding red dwarf stars. |
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B01.00002: Measurement of Average Muon Shower Density Alex Murphy, Jesse Olivieri, Nathan Gould, Christian Locurto, Tomohiko Narita Cosmic rays are high-energy particles that collide with nuclei in the Earth’s atmosphere to create showers of pions that decay into leptons. We detected cosmic rays through the muon showers they produce using a portable telescope array of plastic scintillators. The scintillators emit photons after being ionized by muons that pass through. A photomultiplier tube transforms the ionization energy into electric pulses that we recorded. Low-energy pulses below a threshold that did not come from muons were excluded. Each telescope has two identical paddles suspended by PVC piping with their surfaces in parallel to focus measurements on a certain region of the sky. To calculate muon flux, a two-dimensional solid angle is associated with this region. We worked to correct the solid angle of each telescope with a simulation. The shower density was estimated from the probability that telescopes contained within a muon shower recorded that shower. Additionally, we developed a microcontroller upgrade that reduced our telescope circuit board’s dead time of 276 ms for each recorded muon to less than 15 ms. Future research and more data is needed to support our results. |
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B01.00003: East West Asymmetry of Cosmic Rays Jesse Olivieri, Alex Murphy, Christian Locurto, Nathan Gould, Tomohiko Narita Cosmic rays are, in essence, streams of high energy protons traveling through space. Being positively charged particles, they experience eastward deflection by the Lorentz force when they pass through Earth’s magnetic field. When the protons interact with Earth’s atmosphere they decay into kaons, and pions, which further decay into muons that inherit this deflection as they reach Earth’s surface. According to a simple model, more muons would be traveling eastwards, rather than westward, creating an asymmetry in their flux at Earth’s surface. One of the purposes of this experiment was to observe and investigate this asymmetry using muon telescopes. As each of the telescopes have a unique setting for optimal efficiency, we needed to point them in both east and west directions to measure the asymmetry. Our measurements from one telescope is inconclusive, and another suggests that the flux is greater from a westwards direction. We discuss our results. |
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B01.00004: Testing Kerr-CFT Conjecture for QN modes Calculation Nur-E-Mohammad Rifat, David Kagan, Gaurav Khanna The Kerr black hole solution is one of the most widely used models for astrophysical |
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B01.00005: Falling into Gargantua: How Tidal Forces Affect Objects Approaching the Inner Horizon of a Spinning Black Hole Caroline Mallary, Gaurav Khanna In the movie “Interstellar”, the protagonist Cooper, strapped in his spacecraft, freely falls towards the inner horizon of a large, rapidly rotating black hole called Gargantua. We examine the “tidal” forces that might be experienced by Cooper’s spacecraft due to the inner-horizon singularity of the black hole. In our simplified model, the tidal force experienced by an object falling towards the inner horizon singularity is due to the primordial oscillations of the black hole, and the singularity is a null singularity. We simulated the effect of the tidal force on real materials. We found that the infalling object experiences finite tidal force. This means that an infalling object is not necessarily destroyed by the null singularity of the inner horizon. |
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B01.00006: Von-Neumann Stability and Singularity Resolution in Loop Quantized Schwarzschild Black Hole Alec W W Yonika, Gaurav Khanna In loop quantum cosmology (LQC), the quantum-scale geometry of spacetime is defined by two-dimensional finite-difference (FD) equations. Serious numerical work on the stability and correctness of these models has, so far, been lacking in the literature. Our project is to numerically analyze a novel equation derived to resolve the singularity problem in the Schwarzschild case. We will see under what conditions the stability of this FD model is guaranteed. And we will test if, when evolved, the model gives appropriate results to both LQC and GR predictions in the correct regime. Many benchmarks in progress for this project have already been completed. We will analyze the two-dimensional model in large to small space and time iterations. But, we have already: analyzed the stability conditions for both two-dimensional and two one-dimensional statements, seen that the result converges to a semi-classical result, and have a two-dimensional program to evolve boundary conditions under our stencil. |
(Author Not Attending)
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B01.00007: Abstract Withdrawn
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B01.00008: Lidar Measurements of Atmospheric Transport Features at Mauna Loa Observatory Chris Oville, Jalal Butt, Nimmi Chandra Parikh Chandra Parikh Sharma, John E E Barnes Lidar is an important tool for the detection of atmospheric aerosols which have significant effects on climate and on nutrient and sediment deposition. Due to its mid-Pacific location, elevation, and relative isolation, Mauna Loa Observatory (MLO) is ideally situated for the study of Trans-Pacific aerosol transport phenomena. In this study, MLO's Bistatic CCD Camera Lidar, or CLidar was used to obtain extinction profiles which were then examined for characteristics suggestive of aerosol transport. A 20-Watt, 532-nm Nd:YAG laser was vertically transmitted into the atmosphere above MLO. The side-scatter from atmospheric constituents, such as clouds, aerosols, and air molecules was detected by a wide-angle CCD camera situated 139-m from the laser. The obtained signal was range-normalized using a molecular scattering model and corrected for transmission with a column-averaged aerosol phase function derived from MLO-based AERONET photometer measurements. In several of the datasets, notable aerosol features indicative of particulate transport were observed. |
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B01.00009: Anti-Reflection coated laser diodes in an ECDL system. Chantal Umuhoza, Timothy M M Roach, Sanchi Saitia We have been studying the effect of low-reflectivity coatings designed to improve the frequency control of an Extended Cavity Diode Laser (ECDL) system. The system includes a semiconductor laser diode chip that has two reflective facets. It also uses an external diffraction grating that reflects light back into the laser chip. The competition between reflected light from the external grating and the chip’s front facet to the back facet of the laser diode often leads to an unstable light frequency. This summer, we coated the front facet of the chip with a thin anti-reflection layer of SiO to observe fewer and more predictable frequency mode hops. Using a precision spectrometer, I measured the frequency of light and how it depends on the length of the extended cavity. Through the measurement of the mode frequency spacing of lasers, I was able to classify observed mode hops in terms of either external or chip cavity mode hops. I analyzed the optical behavior of the coated lasers and looked for changes or improvement relative to the uncoated lasers. The results show a successful reduction in chip mode hopping and improved stability of the laser. |
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B01.00010: Alignment of cold Rb atoms by optical pumping Wilber Alfaro Castro, Timothy M M Roach Atoms in a gas have random direction, speed, and orientation. We slow Rb atoms by laser cooling, then use them to study quantum wave reflection. In this, it is advantageous for the atoms’ dipole moments to all point in the same direction. To align these, we apply circularly polarized laser light in a uniform magnetic field. Absorption and scattering of light changes the atomic angular momentum and dipole orientation, a process known as optical pumping (OP). Controlling the orientation will allow us to investigate its effect on the reflection of rubidium atoms. To get a smooth intensity profile, we built a spatial filter combined with a beam expander. In a typical experiment, we first slow down and collect a cloud of atoms, then turn on a uniform magnetic field and OP light beam for 5 msec, and finally measure the reflection of atoms from a magnetized surface. We vary the polarizer used for the OP light, and observe a change in the reflected atom signal. We see a maximum when the atoms’ dipole moments are aligned antiparallel with the magnetic field, and minimum at polarizer angle 90 degrees after, when the dipole moments are aligned parallel to the field, as expected from quantum theory. |
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B01.00011: Measuring diurnal atmospheric tides with a PA-II-SD sensor Seth Gagnon, Arkid Koni, Marko Barbul, Nimmi Chandra Parikh Chandra Parikh Sharma There is a documented phenomenon called the diurnal atmospheric tide. This tide is caused largely by the Sun’s UV radiation on the atmosphere’s ozone layer. One measurable effect of this is in daily pressure variations. These variations can be seen in data worldwide in the form of two daily peaks of atmospheric pressure. These peaks were also found in data taken from a PA-II-SD sensor, which contains a BME280 pressure sensor, documented as a highly reliable and accurate pressure sensor. The close correlation between the data recorded by this sensor and documented international data proves the reliability of the pressure sensor. This particle sensor is also useful for detecting and modeling local weather variations, such as temperature, humidity, and particulate matter concentrations. |
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B01.00012: Synthesis and physical characterization of CuS-graphene oxide nanocomposite materials David Thorne, David Uhl, Peter K. K. LeMaire, Ellen Scanley, Christine C C Broadbridge, Rahul Singhal Supercapacitors or electrochemical capacitors are receiving greater interest because of their high power density, long life, and low maintenance. Copper Sulfide (CuS) and CuS/GO are inexpensive, and have been shown to be promising in the development of high capacity supercapacitors. We have synthesized CuS materials by dissolving copper acetate in a water-butanol solution followed by addition of thiouria, which was dissolved after 30 minutes of stirring. The appropriate quantity of graphene oxide (GO) was then added, and the solution was stirred for another 15 minutes. The resulting solution was placed in an autoclave at 180oC for 24 hours. The precipitated CuS and CuS/GO material was collected using a centrifuge and then dried in an oven for 24 hours. A number of characterization techniques were then employed. The phase purity of each material was determined using XRD studies. Thermal behavior/phase transitions were observed using DSC/TGA. Band-gap was determined by UV/Vis spectroscopic studies. TEM images revealed nano-scale morphology of the synthesized particles. The detailed results will be presented at the APS New England section’s October 2018 meeting. |
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B01.00013: A Quantum Distance Operator and its Use in Measuring the Weak Equivalence Principle Kyle chaisson We introduce a new non-relativistic quantum operator for the distance traveled by a particle in a given interval of time. Our operator measures the integrated expected trajectory of the particle. If its expectation value depends on the particle's mass we can infer that the particle's motion is also dependent on its mass and thus violates the Weak Equivalence Principle (WEP). As a proof of concept we use the operator to analyze the expected distance traveled by a free Gaussian wavepacket in free space with some initial momentum. The distance such a particle travels becomes close to light-like as its mass vanishes and agrees with the classical result for macroscopic masses. This result shows that different versions of the WEP, while equivalent to each other in the classical theory, are, in fact, incompatible in quantum mechanics. Also considered is the similar problem of a particle in a spherical well potential. |
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B01.00014: Electron beam production and beam profile monitoring Daniel Mendez, Paul Oxley Collision experiments between an ion beam and an atom beam are subject to inefficiencies without knowledge of the size, shape and intensity of the ion beam. Here we describe the construction of a beam profile monitor (BPM) to accurately provide this data, and an electron beam system which will allow future testing of the BPM with an electron beam. The BPM is comprised of a wire grid in which currents are induced when a charged particle beam strikes them. These currents can be measured to determine the size, shape, and intensity of the beam. The electron beam system consists of a heated filament, an acceleration electrode, and a Faraday cup used to measure the intensity of the electron beam. Electric and magnetic fields are also applied to steer the electrons accurately into the cup. Our data shows electron beam currents of several hundred nano-amps. The current varies significantly with time, which we attribute to changes of the filament surface composition as it is heated. Data showing the enhancement of the electron current with increased acceleration are also shown, in addition to a study of the secondary electrons emitted from the Faraday cup surface. |
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B01.00015: Simultaneous DSC/TGA studies of CsNO Alicja Urbanczyk, Marko Barbul, William Tuxbury, Peter K K Lemaire CsNO3 is one of a group of Nitrates that have been studied extensively due to their interesting polymorphic transformations at various temperatures. It is also of interest as an oxidizer for pyrotechnic compositions and exhibits pyroelectric behavior at low temperatures. Literature information on its melting point as well as its solid to solid transition varies as much as 10 degrees Celsius. In this work, high purity (99.99%) CsNO3 were studied using a TA Instruments SDT Q600 Simultaneous Differential Calorimeter/Thermogravimetric Analyzer (DSC/TGA). The DSC/TGA measured the heat flow simultaneously with mass changes of the CsNO3 as a function of temperature from room temperature to 520 C˚ at heating rates varying between 2.5 and 25 C˚/min. Two observed points of interest are the solid to solid transition and a melting transition occurring around 154 C˚ and 406 C˚ respectively. The Universal Analysis software was used to obtain the onset and peak transition temperatures, and other values. The Zero heating rate method, in which the transition temperatures are obtained by extrapolation to zero heating rate, was used to ascertain more precise transition temperatures. These results and some observed events at the melting point will be the primary focus of the presentation.
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B01.00016: Oscillon formation from collapsing bubble induced phase transitions Damian R R Sowinski Oscillons have been shown to form in degenerate double well potentials from the collapse of bubbles of one type of vacuum embedded in a sea of the other. In this work we look at asymmetric potentials, finding a region of parameter space that supports infinitely long lived oscillons. This regions relationship to critical resonances is studied. The formation of oscillons in scenarios where the bubble successfully initiates a phase transition is also examined. |
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B01.00017: Overcoming Challenges in GPU Computing for Scientific Applications: SoC Solutions to PCI Bandwidth Limitations Connor Kenyon, Glenn Volkema, Gaurav Khanna Traditionally, with high performance GPU-based computing, the PCI memory bandwidth has been a limiting factor on performance. To avoid this problem, System-on-a-Chip (SoC) devices are explored as a potential solution. The main benefit of these devices is unified memory, which allows zero-copy algorithms to be implemented, eliminating the need for any PCI memory transfer. These devices are analyzed in both performance and cost and are compared to a modern discrete GPU, an Nvidia V100. To compare these, benchmarks from the SHOC benchmark suite were used to analyze performance on different commonly used algorithms for scientific computing in physics. |
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B01.00018: Modified Finite Difference Method on the 1-D Schrodinger Equation Trevor A A Robertson, Jonathan Pierre-Louis, Jay Wang The time-dependent Schrödinger equation (TDSE) is a fundamental law in understanding the states of many microscopic systems. Such systems occur in nearly all branches of physics and engineering, including atomic, high-energy, and solid-state physics just to name a few. A robust and efficient algorithm to solve the TDSE would be an essential goal in these respective fields. In this study we use the well-known method for solving the TDSE, the finite difference method (FDM) but with an important modification: formulating the TDSE in a form suitable for symplectic integration to conserve flux. In this presentation we discuss case studies and present results on stability, flux conservation, as well as scattering probabilities in 1D potentials. We show that the modified method is a stable, promising, and accurate method for linear domains over lower dimensions with arbitrary potentials. We also discuss challenging problems of scaling to higher dimensions and more refined grids. |
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