Bulletin of the American Physical Society
2019 Fall Meeting of the APS Division of Nuclear Physics
Volume 64, Number 12
Monday–Thursday, October 14–17, 2019; Crystal City, Virginia
Session SL: Mini-Symposium on Fundamental Symmetries: Theory and Experiment VI |
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Chair: Grant Riley, University of Tennessee Room: Salon H |
Thursday, October 17, 2019 10:30AM - 10:42AM |
SL.00001: The Nab Neutron Decay Correlation Experiment Christopher Crawford Neutron decay correlations provide a clean probe of the CKM matrix element $V_{ud}$, and provide limits on new tensor and scalar interactions. The Nab experiment is currently being commissioned at ORNL to measure the antineutrino-electron correlation $a$ with a relative uncertainty of $10^{−3}$, and the Fierz interference term $b$ with an overall uncertainty of $3\times10^{−3}$. This experiment uses a new technique to determine the antineutrino-electron angle from the energy of the electron and proton, detected in coincidence. I will present the physical design, modes of running, and projected sensitivity of this experiment. [Preview Abstract] |
Thursday, October 17, 2019 10:42AM - 10:54AM |
SL.00002: Magnetometry of the Nab Spectrometer Elizabeth Scott The Nab experiment uses a novel asymmetric superconducting magnetic spectrometer and two large-area segmented Si detectors to extract the neutron beta decay electron-neutrino correlation coefficient \textit{a} and the Fierz interference term \textit{b} from the proton momentum and electron energy spectrum. Nab was designed to achieve a $10^{-3}$ relative uncertainty in \textit{a}, and this requires a detailed characterization and analysis of the magnetic field in the spectrometer. Using a Hall probe calibrated to better than $10^{-3}$ relative precision and the laser trackers that can measure distances within tens of microns, we mapped a field that ranged from tens of gauss to 4.2 Tesla over 7 meters. This talk will cover the measurement technique, results of the field characterization scheme, and the field expansion methods used. [Preview Abstract] |
(Author Not Attending)
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SL.00003: Towards Polarimetry for the Nab Experiment Chelsea Hendrus The Nab experiment at the Fundamental Neutron Physics Beamline (FnPB) at the Spallation Neutron Source (SNS) aims to make precision measurements of the electron-neutrino correlation, a, and Fierz interference term, b, associated with the beta decay of free neutrons. Tiny residual polarization of the incident beam presents a potential source of systematic error in the measurement of a. In order to understand and mitigate these effects we must measure the beam polarization and the efficiency of our neutron spin flipper. If we use $^3$He polarizers to accomplish these measurements, it will require careful control of the magnetic environment along the beam, in order to both assure adiabatic spin transport of the neutrons, and prolong the polarization lifetime the $^3$He cells. However the space for incorporating the necessary components is limited, and requires the use of novel approaches to magnet construction to obtain the requisite fields. This talk will describe the polarimetry setup and simulated spin transport results. [Preview Abstract] |
Thursday, October 17, 2019 11:06AM - 11:18AM |
SL.00004: Nab Detector Timing Studies Glenn Randall Precise measurements of neutron beta decay correlations provide a potential window to new physics related to the weak sector. The Nab experiment will measure the electron-neutrino correlation coefficient and Fierz interference term to as of yet unattained precision. Observables for Nab are electron energy and proton time of flight, which can be converted to proton momentum. Nab's error budget calls for proton time of flight uncertainty less than or equal to 0.3 ns. One major systematic in proton time of flight is detector charge collection time. To characterize this, Nab will have to do a high precision in situ measurement of the Nab Si detector charge collection time as a function of particle ID and energy. This talk will focus on our planned procedure as well as detector background and other measurements done in preparation. [Preview Abstract] |
Thursday, October 17, 2019 11:18AM - 11:30AM |
SL.00005: (CEU) Simulating Inside Detector Physics for the Nab Experiment Tom Shelton, Leah Broussard The Nab experiment will measure the electron-neutrino correlation coefficient and the Fierz interference term in unpolarized free neutron beta decay with high precision allowing the probing of the standard model and the weak interaction. To meet these precision goals, uncertainty in the average proton time-of-flight must be within 0.3 ns. To achieve this precision, we mush account for the systematic bias created from deposition depth of the particles in the silicon detector due to drift times of quasi-particles resulting in differing charge collection timings. Simulation of the inner detector physics is critical in understanding the significance of this consequence. By characterizing data sets from CASINO and integrating these into custom charge propagation code, we were able to construct the resultant waveforms and determine the timing offset. We will present the process of said simulations along with analysis of this effect. [Preview Abstract] |
Thursday, October 17, 2019 11:30AM - 11:42AM |
SL.00006: (CEU) Pile-up Detection in Silicon Detector Signals via Machine Learning for the Nab Experiment David Perryman Pixelated Silicon detectors and shaping electronics in the Nab Experiment will produce digitized waveforms from which energy and timing information can be extracted. Electrons that escape and return to the same pixel, or particles that accidentally arrive in the same waveform can distort results if not detected and accounted for. This talk will present a machine learning approach to detecting these events using feedforward dense, convolutional, recurrent, recurrent convolutional, and residual convolution networks. 1-dimensional variations of the popular ResNet50 and ResNet152 have been implemented. This talk will also discuss a Generative Adversarial Networks (GANs) and dimensionality reduction approach to investigating weaknesses in pile-up detection. [Preview Abstract] |
Thursday, October 17, 2019 11:42AM - 11:54AM |
SL.00007: GPU Based Nearline Analysis for the Nab Experiment David Mathews The Nab neutron decay correlation experiment will use two 127-pixel silicon detectors digitized at 250 MS/s to record the energy and time-of-flight of electron-proton coincidences for full kinematic reconstruction of $\theta_{e\nu}$. Raw waveform data will be collected from ~30 pixels per event at an anticipated rate of 50 kHz for offline analysis. While first-order timing and energy are available from the data acquisition firmware, higher resolution is desired for immediate analysis. We developed a GPU-based least-squares fitter which decompresses the raw datastream and fits the amplitude of multiple template waveforms and background noise in real time as part of the data acquisition pipeline. These same algorithms will be used on GPU farms for offline processing of the final results. [Preview Abstract] |
Thursday, October 17, 2019 11:54AM - 12:06PM |
SL.00008: Characterizing a silicon detector alpha response for the Beta-decay Paul Trap Louis Varriano, Guy Savard, Jason A Clark, Nicholas D Scielzo, Daniel P Burdette, Mary Burkey, Aaron Gallant, Tsviki Y Hirsh, Ralph Segel The Beta-decay Paul Trap (BPT) at Argonne National Lab studies the weak interaction with short-lived radioactive ions at low energies. The BPT measures the beta-neutrino angular correlation coefficient $a_{\beta \nu}$ in the pure Gamow-Teller decay of $^{8}$Li and $^{8}$B (decaying to $^{8}$Be$^*$ with immediate break up to 2 alpha particles) to search for a tensor component of the weak interaction. By using double-sided silicon strip detectors (DSSSDs) to detect the decay products, the BPT has improved the tensor current limit from the low energy side for the first time in over fifty years. To further improve this limit, with a measurement goal of 0.1\% uncertainty in $a_{\beta \nu}$, it is necessary to fully understand the DSSSD response to alphas across a broad range of energies, including all undetected energy losses. In addition, it is necessary to understand the calibration source alpha distribution, as the sources used by the BPT are not lossless. This work characterizes the source alpha distribution and the DSSSD alpha response, which can be applied to other experiments that rely upon an accurate measurement of alpha energy. [Preview Abstract] |
Thursday, October 17, 2019 12:06PM - 12:18PM |
SL.00009: Every Fundamental Particle, Nucleus, Atom, Molecule, Compound and/or Ion or Heavenly Bodies Exhibit No Motion, Linear, Rotational and/or Vibrational Motion, Singly or in Some Combination When Created Which May Be Modified By External Forces: A Natural Law Stewart Brekke All masses and mass groups, when created, will have due to excess energy when created, Linear, Rotational, and/or Vibrational motion, singly or in some combination, all, some or none, may be altered by external forces. The basic energy equation for any newly created mass is $E=m_0c^2 + 1/2m_0v^2 + 1/2I\omega^2 + 1/2kx^2.$ $I\omega^2$ is the rotational kinetic energy and the factor $kx^2$ is the kinetic energy of a simple harmonic oscillator although any type of oscillator may result from excess energy of the mass's creation. Since all masses and mass groups obey this behavior apparently everywhere in space. for example all galaxies, stars, planets and satellites have been found to be capable of moving linearly (orbital motion is linear motion under the influence of an external force field such as gravitational force),rotating and vibrating as are all nuclei,molecules, ions and compounds, are capable of moving linearly, rotating and/or vibrating singly or in some combination on earth, this behavior can be considered a natural law describing the type of motion possibilities. [Preview Abstract] |
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