Bulletin of the American Physical Society
2020 Fall Meeting of the APS Prairie Section
Volume 65, Number 22
Friday–Sunday, November 13–15, 2020; Virtual
Session A09: Poster Session (4:00-5:00pm) |
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Chair: Zack Sullivan, Illinois Institute of Technology |
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A09.00001: Cryogenic electronics control and characterization for dark matter detection Jialin Yu, Rakshya Khatiwada, Mohamed Hassan Axions are theoretically motivated ultralight cold-dark-matter (CDM) candidates. Superconducting qubits and quantum-noise limited amplifiers such as Traveling Wave Parametric Amplifier (TWPA) can be utilized to develop axion dark matter detectors. In the COVID era, we successfully set up a remote controlled system for characterizing TWPA which included detailed measurements of noise and parametric gain of two of these amplifiers. Furthermore, we designed PCB boards for a new dilution refrigerator infrastructure that will be utilized to study the effects of ambient and cosmic radiation in the qubits. Our results will be used to study qubits and develop qubit and quantum amplifiers based dark matter detectors. [Preview Abstract] |
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A09.00002: Record Gradients of 50 MV/m in TESLA SRF Cavities via Modified Low T Bake. Daniel Bafia, Anna Grassellino, Alexander Romanenko, Zuhawn Sung, John Zasadzinski This poster will discuss the modified low temperature bake capable of giving unprecedented accelerating gradients above 50MV/m for 1.3GHz TESLA-shaped niobium SRF cavities in CW operation. A puzzling bifurcation in vertical test results is observed after retesting cavities without disassembly in between, yielding performance that ranges from exceptional to above state-of-the-art. Atomic Force Microscopy studies on cavity cutouts give a possible mechanism responsible for this branching in performance, namely, the dissociation and growth of previously unobserved room temperature niobium nano-hydrides that exist near the RF surface. Such nano-hydrides are made superconducting only through the proximity effect. In-situ low temperature baking of cavity cutouts reveals a dissociation of these room temperature nano-hydrides. These results explain the improved performance of cavities subject to similar in-situ heating in the dewar prior to RF testing. [Preview Abstract] |
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A09.00003: Field emission mitigation studies in 1.3GHz LCLS-II cavities via \textit{in situ} plasma processing Bianca Giaccone, Martina Martinello, Paolo Berrutti, Oleksandr Melnychuk, Anna Grassellino, Dmitri Sergatskov, Dan Gonnella, Marc Ross, Marc Doleans, John Zasadzinski Field emission (FE) is one the main factors that can limit the accelerating gradient and quality factor at which a superconducting radio frequency cavity can operate. SRF cavities processing and preparation has been optimized to minimize the chances of introducing field emitters, however the cavity's performance can deteriorate over years of operation of the accelerator. We are studying plasma processing as a possible method to reduce FE caused by hydrocarbon contamination, specifically for the Linac Coherent Light Source II (LCLS-II) SRF cavities. The procedure will be applied \textit{in situ }in the cryomodules, allowing to address FE mitigation without disassembling the accelerator. Having developed a novel method of plasma ignition for LCLS-II 1.3GHz cavities, we applied plasma processing to clean cavities, and cavities with natural field emission or artificially contaminated. All the cavities were cold tested before and after plasma processing to compare their performance. It was proved that the technique is successful in mitigating hydrocarbon related field emission, without affecting the high Q-factors and quench fields that are typical of LCLS-II N-doped cavities. [Preview Abstract] |
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A09.00004: Using Gaussian Process Regression to Integrate the Transition Structure Factor Curve for the Many-Body Correlation Energy Laura Weiler, Tina Mihm, James Shepherd We apply Gaussian process regression to transition structure factor curves for a range of electron numbers and integrate to attain the correlation energy. We find that with this procedure we are able to approximate the thermodynamic limit correlation energy for the cost of relatively small system sizes. This has possible applications to the electronic structure and materials design communities as it provides a cost-effective route to the thermodynamic limit correlation energy using coupled cluster doubles calculations on the uniform electron gas. [Preview Abstract] |
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A09.00005: Block Co-Polymer Nanopatterning For Emerging Technologies Involving Undergraduate Students at Illinois State University Marcos Perez, Mahua Biswas With the rise in emerging technologies in the field of optoelectronics, fabrication of plasmonic and photonic nanomaterials is becoming imperative. To delve into the nanoworld, Illinois State University's Applied Nanomaterials Lab is utilizing block co-polymers (BCP) template method to fabricate nanopatterns of inorganic materials of titanium dioxide and gold. This fabrication procedure, known as BCP lithography, is a promising, simple, low cost route, which has already shown great promise in the microelectronics industry. Self-assembled Polystyrene-block-poly methyl methacrylate (PS-b-PMMA) and Polystyrene-block-poly (2-vinylpridine) (PS-b-P2VP) BCPs nanostructures are fabricated first using a spin casting method for making the template, followed by selective deposition of inorganic precursor into PMMA and P2VP using solution process method and the subsequent removal of the BCP template. We are characterizing these nanostructures using scanning electron microscopy, x-ray diffraction and UV-VIS spectroscopy to understand the morphological, physical and optical properties. The fabricated nanostructures with long range patterns will be attractive for optical devices and other applications. [Preview Abstract] |
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A09.00006: Theoretical Phase Stability of Silicon Nanomembranes Under Pressure Joel Ambriz Ponce, William Parker The wide range of applications of semiconducting silicon surround us in electronic, optical, and mechanical devices.Flat, tens-of-nanomemter-thick membranes of pure silicon can now be synthesized and thickness-dependence changes in membrane properties have been reported.To understand and predict the evolution of these properties, we model atomistic silicon slabs at the electronic level using density functional theory at varying levels of exchange-correlation functional. In particular, we investigate the pressure-based transition from the ambient-condition diamond phase to the higher-pressure beta-tin phase under compression both uniaxially out-of-plane uniaxial and biaxially in the plane of the membrane. We calculate the transition pressure and volume as well as the elastic properties of each phase at varying slab thicknesses. [Preview Abstract] |
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A09.00007: Density Functional Perturbation Theory Parameter Convergence for Phonons Ryan Glusic, William Parker Phonons determine material properties such as thermal and electrical conductivity. Allowed modes are solutions to the characteristic equation for the dynamical matrix. One method for constructing the dynamical matrix is density functional perturbation theory (DFPT) in which potential perturbation by atomic displacements is calculated for all unique combinations. The resulting energy second derivatives constitute the dynamical matrix. DFPT contains many parameters, each of which requires convergence to within acceptable numerical error. Using several electronically distinct solid-state structures as test cases, we investigate varying these parameters and the resulting phonon frequencies in terms of their relative and absolute error from a highly converged value. We use also compare the effect of the uncontrolled approximations of DFPT for electronic structure calculations (exchange-correlation functional and pseudopotential) against experimental frequencies. We aim to provide advice on choosing parameters to minimize computation time while producing accurate results in DFPT calculations. [Preview Abstract] |
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A09.00008: Optical band gap of bismuth vanadium borate glasses Mazharul Islam Mondal, P.K. Babu, Saisudha Mallur The optical band gap (E$_{\mathrm{opt}})$ is an important parameter that depends on the electronic band structure of a glass and therefore, can serve as a basis to investigate the variation in the band structure. Heavy metal oxide glasses containing V$_{\mathrm{2}}$O$_{\mathrm{5}}$ have potential applications in optoelectronic devices and electrochromic display devices. We prepared bismuth vanadium borate glasses with the composition \textbf{30Bi}$_{\mathrm{\mathbf{2}}}$\textbf{O}$_{\mathrm{\mathbf{3}}}$\textbf{-(70-x) B}$_{\mathrm{\mathbf{2}}}$\textbf{O}$_{\mathrm{\mathbf{3}}}$\textbf{-x V}$_{\mathrm{\mathbf{2}}}$\textbf{O}$_{\mathrm{\mathbf{5}}}$\textbf{ (x}$=$\textbf{ 0.1, 1, 2, 3, 4 mol{\%}) }and studied the optical absorption spectra of this ternary system as a function of vanadium composition. We carried out a detailed analysis of the optical absorption edge using the Mott-Davis model and determined E$_{\mathrm{opt\thinspace }}$for all these glasses. We found that, with increasing V$_{\mathrm{2}}$O$_{\mathrm{5}}$ content, the absorption edge shifts towards longer wavelengths and the optical band gap decreases from 2.63 eV to 2.33 eV. The type of transition between the valence band and the conduction band is determined to be indirect allowed transition. [Preview Abstract] |
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A09.00009: Using cold atoms to sympathetically cool a levitated nanosphere Eduardo Alejandro, Cris Montoya, William Eom, Apryl Witherspoon, Andrew Geraci In search of new physics, the mesoscopic regime can be probed by a single 85 nm silica nanosphere, cooled to the vibrational ground state by optically-coupled cold atoms. Rubidium atoms are loaded in a MOT and optical tweezers trap a single nanosphere in a separate chamber. The systems can then be coupled for sympathetic cooling through radiation pressure forces mediated by a 1-D optical lattice. Using laser cooling techniques, the atoms can sympathetically cool the center of mass motion of the trapped sphere. Such cooled spheres can be used for precision sensing, matter-wave interferometry, and tests of quantum coherence in the mesoscopic regime. [Preview Abstract] |
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A09.00010: Detecting high-frequency gravitational waves with optically-levitated sensors. Zhiyuan Wang, George Winstone, Nancy Aggarwal, Mae Teo, Masha Baryakhtar, Shane Larson, Vicky Kalogera, Andrew Geraci Optically-trapped and cooled micro-scale sensors within a cavity can be used to detect gravitational waves in the \textasciitilde 10kHz to \textasciitilde 300kHz band, which is beyond the optimal sensitivity range of other experiments like LIGO. The levitated sensors can search for binary coalescence of sub-solar-mass primordial black holes, the effect of QCD axions on astrophysical black holes, and other gravitational wave sources at high frequencies. We present the experimental status of the 1-meter prototype that is under development as well as the theoretical results for new physics from high-frequency gravitational waves. [Preview Abstract] |
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A09.00011: NuMI Beam Monitoring Simulation and Data Analysis Yiding Yu, Pavel Snopok, Katsuya Yonehara, Athula Wickremasinghe, Amit Bashyal, Nilay Nilay Bostan, Tom Tom Carroll With the Main Injector Neutrino Oscillation Search (MINOS) experiment decommissioned, muon and hadron monitors became an important diagnostic tool for the NuMI Off-axis $v_\mu$ Appearance (NOvA) experiment at Fermilab to monitor the Neutrinos at the Main Injector (NuMI) beam. The goal of this study is to maintain the quality of the monitor signals and to establish correlations with the neutrino beam profile. We report here on the progress of the beam data analysis and comparison with the simulation results. [Preview Abstract] |
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A09.00012: Probing Nucleon Structure in Drell-Yan and J/Psi production at COMPASS April Townsend COMPASS is a fixed target experiment in the North Area of CERN. One of the primary goals of its broad physics program is to study the transverse momentum dependent (TMD) parton distribution functions (PDFs) that describe the spin structure of nucleons. To extract observables related to TMD PDFs, COMPASS uses both Semi-Inclusive Deep Inelastic Scattering (SIDIS) and the Drell-Yan (DY) process. Results related to the quark Sivers functions are especially interesting, as these functions are expected to change sign between SIDIS and DY. Here we focus on the DY portion of the COMPASS program. In 2015 and 2018, COMPASS collected DY data by scattering a negative pion beam off a transversely polarized ammonia target. The most recent COMPASS results agree with the predicted sign flip of the Sivers function between SIDIS and DY. During the DY runs, COMPASS also recorded many J/Psi events. Single-spin asymmetries in J/Psi production may give access to the gluon Sivers function and may improve our understanding of the J/Psi production mechanism. The reconstruction of raw experimental and Monte-Carlo data, necessary to perform physics analysis, was primarily realized exploiting the parallel computing resources of the Blue Waters supercomputer at NCSA and the Frontera supercomputer at TACC. [Preview Abstract] |
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A09.00013: Thermal Fluctuations in Nuclear Pasta Cal Forsman, Matt Caplan, Andre Schneider All stars maintain an equilibrium between the pressure in their cores and gravity compressing them. When massive stars exhaust their fuel nuclear fusion in the core ceases and can no longer support the core against gravitational compression. A core-collapse supernova occurs, and the collapsed core remains as a neutron star. Neutron stars are significantly more compact and thus much denser. At these high densities protons and neutrons rearrange into structures known as `nuclear pasta' which are theorized to generate gravitational waves on rotating neutron stars. We study thermal fluctuations in nuclear pasta at finite temperatures using molecular dynamics simulations. We render these simulations in 3D using Paraview to study the evolution of nuclear pasta with increasing temperature. We resolve a melting transition above which the structure breaks down. At high temperatures below the melting transition various defects such as holes and filaments spontaneously form and dissolve, and we observe high surface roughness. At low temperatures defects exist but are infrequent and short lived. We characterize the surface of the pasta structures with the Minkowski functionals and find power law deviations in surface curvature which may impact observable properties of neutron stars. [Preview Abstract] |
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A09.00014: Benefits of MeV-scale reconstruction capabilities in large liquid argon time projection chambers Whitmaur Castiglioni, Will Foreman, Bryce Littlejohn, Matthew Malaker, Ivan Lepetic, Andrew Mastbaum Using truth-level Monte Carlo simulations of particle interactions in a large volume of liquid argon, we demonstrate physics capabilities enabled by reconstruction of topologically compact and isolated low-energy features, or `blips,' in large liquid argon time projection chamber (LArTPC) events. These features are mostly produced by electron products of photon interactions depositing ionization energy. The blip identification capability of the LArTPC is enabled by its unique combination of size, position resolution precision, and low energy thresholds. We show that consideration of reconstructed blips in LArTPC physics analyses can result in substantial improvements in calorimetry for neutrino and new physics interactions and for final-state particles ranging in energy from the MeV to the GeV scale. Blip activity analysis is also shown to enable discrimination between interaction channels and final-state particle types. In addition to demonstrating these gains in calorimetry and discrimination, some limitations of blip reconstruction capabilities and physics outcomes are also discussed. [Preview Abstract] |
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A09.00015: Construction of Anode Plane Assembly Detectors for the DUNE Far Detector Maxwell Herrmann, James Thompson, Cole Dorman An international consortium will commence construction of the first module of Fermilab’s Deep Underground Neutrino Experiment (DUNE) Far Detector this year. The Anode Plane Assemblies (APA’s) form the central component of the detector, instrumented with wire planes, photon detectors, and readout electronics. Prototype APA’s have been constructed in the US at Physical Sciences Laboratory in Madison Wisconsin as well as in the U.K. Work is being done by University of Iowa students to estimate effects of alignment on electron transparency for the DUNE APA using the Garfield simulation program. The procedure for the construction and quality assurance of these large precision detectors, implementation in ProtoDUNE, and plans for construction of the full ensemble of APA detectors for the first two modules of the DUNE Far Detector will be presented. [Preview Abstract] |
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A09.00016: Effects of Supernovae Cosmic Rays on the Earth's Atmosphere Alexander Yelland Geochemical evidence has established that at least one, if not more, supernova explosions occurred within 50-100 pc of Earth about 2.5 million years ago. Recent work estimated the cosmic ray flux arriving at Earth for supernovae at 100 pc and 50 pc under different assumptions about particle transport. Here, we report on the re-examination of some of those results using an updated computation of the flux of protons under an empty-space diffusive transport approximation. We find that some cases reported in past work are an overestimate of the flux. This has implications for modeling the atmospheric chemistry changes. Our current work includes updating those simulations and extending calculations to closer supernova distances. [Preview Abstract] |
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