Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session L10: Fundamental Measurement Science |
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Sponsoring Units: GIMS Chair: Joseph Hagmann, National Institute of Standards and Technology Room: 108 |
Wednesday, March 4, 2020 8:00AM - 8:12AM |
L10.00001: Propellant Quantity Gauging in Microgravity Using Radio Frequency Tank Modes Gregory Zimmerli, Marius Asipauskas, Cameron Dong The Radio Frequency Mass Gauge (RFMG) is a novel propellant quantity gauging technique developed at NASA for the purpose of gauging cryogenic propellant tanks in low-gravity. The RFMG operates by sensing several resonant electromagnetic modes of a tank and comparing the measured tank mode frequencies to a lookup table of results from several thousand numerical simulations. The numerical simulations are performed in advance in order to predict the electromagnetic eigenmode frequencies at different propellant fill levels, liquid configurations, and temperatures. A best match between measured and simulated eigenmode frequencies is used to gauge the fluid mass inside the tank. An RFMG instrument flew on the International Space Station (ISS) and was used to gauge the mass of liquid methane in a 50 L tank as part of the Robotic Refueling Mission 3 (RRM3) payload operations. Shifts to the measured tank RF spectra during the mission indicated significant changes to the fluid configuration as a result of various ISS maneuvers and payload tests. During the four months of RRM3 cryogenic payload operations the RFMG produced a mean gauged mass of 19.0 kg, in agreement with the expected value, with a one-sigma error distribution of ±2% of the full-scale mass. |
Wednesday, March 4, 2020 8:12AM - 8:24AM |
L10.00002: Stretching the bandwidth of physical measurements by compressed sensing Shunsuke Fujisawa, Susumu Fukatsu The bandwidth limit is an issue in any class of physical measurements. To restore the original full-band spectrum from the available data sets that have been severely bandwidth-limited due to measurement is a challenge. Compressed sensing (CS), which is essentially an estimation based on L1 norm minimization, is a powerful technique to retrieve signals using a small number of clues on the assumption of sparsity. Here we attempt the CS in frequency domain to restore the otherwise lost part of the spectrum with good fidelity. The proof-of-concept experiment was done on a model system with bandwidth-limiting properties by first acquiring the prior knowledge of its step response in the form of discretized impulse response function. The original input waveform was mixed with random signal to spread the spectrum over the entire frequency range, i.e., omni-frequency heterodyne. Then the CS was implemented by using repetitive interleaved random sampling over the captured signals that are linearly coupled with the random mixing signals through the step response. Successful recovery of the original full-band spectrum with well over 70-% fidelity holds promise for high-Z and the many strongly bandwidth-limiting measurements. Single-shot and real-timeliness issues will also be discussed. |
Wednesday, March 4, 2020 8:24AM - 8:36AM |
L10.00003: The Role of Noise in PT-Symmetric Systems Bahar Jafari Zadeh, Fred M Ellis PT-symmetric systems have provided a remarkable variety of phenomena related to signal manipulation ranging from unconventional state management to enhanced sensitivity at exceptional points. Although ideal models have been proposed for many different systems, the role of noise has typically not been the focus of previous papers. In this study, we compare the consequences of noise, both internally generated and externally received, between a non-PT regenerative resonator and a PT resonator pair. We show that, in general, there is no advantage of the PT system from a signal-to-noise perspective. |
Wednesday, March 4, 2020 8:36AM - 8:48AM |
L10.00004: Characterization of Acoustic Standing Waves Surrounding A Cylindrical Inertia Block in an Ultra-Low Vibration Facility Juliet Nwagwu Ume-Ezeoke, Yu Liu, Jennifer E. Hoffman In facilities working with scanning tunneling microscopes (STM), it has been found that the vibrations of the surface on which the STM is placed can significantly alter results. To mitigate this issue, more research is being done into low-vibration laboratories. The low-vibration facility at Harvard University employs a massive cylindrical inertia block mounted on pneumatic isolators. The block has been made cylindrical to avoid coupling of acoustic standing waves between the walls of the room and the inertial block. We have used COMSOL Multiphysics to perform finite element analysis to simulate coupling of the acoustic standing waves in the room to the resonant modes of the inertial block. To check the results of the simulation, a speaker is used to generate a range of frequencies in order to excite the block. We then measure the acoustic standing waves using a microphone. |
Wednesday, March 4, 2020 8:48AM - 9:00AM |
L10.00005: Optimizing mechanical resonator sensitivity for thin film internal friction and shear modulus measurements Thomas Metcalf, Xiao Liu, Battogtokh Jugdersuren The double-paddle oscillator is a mechanical resonator with an extremely high qualty factor at liquid helium temperatures, enabling sensitivie measurements of the internal friction and shear modulus of thin film materials. Since its development more than twenty years ago, several energy loss mechanisms that establish its background quality factor have been identified and quantitatively modeled, including thermoelastic dissipation and attachment loss. Building on work that led to the successful design of a companion resonator (one that measures Young’s modulus), here we use Finite Element Modeling (FEM) of variations on resonator geometry to seek lower thermoelastic and attachement losses as well as to increase the frequency-space separation of resonaont modes. Four candidate resonator geometries were identiified and fabricated. We compare measurements of these designs to that of the standard resonator geometry. |
Wednesday, March 4, 2020 9:00AM - 9:12AM |
L10.00006: Progress on the Detection of Single Free Helium Atoms through Field Ionization for a Dark Matter Detector David Osterman, Humphrey J Maris, George M Seidel, Derek Stein
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Wednesday, March 4, 2020 9:12AM - 9:24AM |
L10.00007: Digitizer nonlinearity correction with an AC Josephson Voltage Standard Jason M Underwood, Bryan C Waltrip High-fidelity conversion of physical measurement data to the digital domain is desirable in many fields of science. Numerous techniques are available for the correction of nonlinearities in analog-to-digital converters (ADCs). However, implicit in these methods is the availability of a source with a higher resolution and/or lower nonlinearity than that of the ADC under test, which is challenging to realize for ADCs with resolutions exceeding 20 bits. An AC Josephson Voltage Standard (ACJVS) is capable of generating pure tones with distortion below 1 part per billion and amplitude accuracies in the single parts per million. These characteristics make it an ideal source for evaluating nonlinearities in high-resolution digitizers commonly used in audio and dynamic force measurements. In this talk I will describe the framework for performing such nonlinearity corrections with the ACJVS, share results and limitations, and discuss possible ways that this technique can be used to account for phase distortion. |
Wednesday, March 4, 2020 9:24AM - 9:36AM |
L10.00008: Effect of chiral dopant and nanoparticles on liquid crystal based microlenses Kelum Perera, Ahlam Nemati, Torsten Hegmann, Antal Istvan Jakli Microlenses apply to optical devices such as biomimetic optical systems, optical fiber switches, light deflection devices, solar concentrators, etc. [1,2]. Piotr et al.[1] demonstrated and characterized chiral nematic liquid crystal (LC) films suspended in the transmission electron microscope (TEM) grids that form converging spherical microlenses when immersed in water. Here we report on the tunability of the focal length of the TEM grids suspended 4-cyano-4-pentylbiphenyl (5CB) microlenses by adding different concentrations chiral dopant CD1 (ZLI 811) and mixing chiral nanoparticles with 5CB to detect various sources of chirality and make various shapes of microlenses with tunable focal lengths. Additionally, the effects of chiral dopants on the hybrid alignment of LC microlenses is also presented. |
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