Bulletin of the American Physical Society
APS April Meeting 2020
Volume 65, Number 2
Saturday–Tuesday, April 18–21, 2020; Washington D.C.
Session R14: Neutron PhysicsOn Demand
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Sponsoring Units: DNP Chair: Shannon Hoogerheide, National Institute of Standards and Technology (NIST) Room: Virginia A |
Monday, April 20, 2020 1:30PM - 1:42PM On Demand |
R14.00001: Ultracold Neutron Density for the Neutron Electric Dipole Moment Search at Los Alamos National Laboratory Douglas Wong, Austin Reid, Taufique Hassan The neutron electric dipole moment (nEDM) search at Los Alamos National Laboratory (LANL) will use the Ramsey method of oscillatory fields on stored ultracold neutrons (UCNs) to perform a measurement with a sensitivity of $\sigma\left( d_n\right)=3\times10^{-27}e\cdot cm$. Achieving this statistical sensitivity requires a large stored UCN density, long storage lifetime, long spin coherence time, and careful neutron transport from the UCN source to the experiment. We discuss progress on UCN transport and storage at the envisioned location of the experiment. Thus far, we have succeeded in storing sufficiently large numbers of polarized UCNs for a sufficiently long period of time in a realistic, prototype storage cell. Additionally, we describe the use of Monte Carlo simulations to understand neutron transport measurements, and to predict expected neutron spin contrast and lifetime in the final storage geometry. [Preview Abstract] |
Monday, April 20, 2020 1:42PM - 1:54PM |
R14.00002: Measurement of the expected 57 keV neutron anti-resonance in $^{40}$Ar using a time of flight neutron beam Tyler Erjavec A measurement of the transmission coefficient for neutrons through a thick ($\sim$3 atoms/b) natural liquid argon target in the energy range 40-70 keV has been performed by the Argon Resonance Transmission Interaction experiment (ARTIE) using a time of flight neutron beam at Los Alamos National Laboratory (LANL). In this energy range theory predicts an anti-resonance in the $^{40}$Ar cross section near 57 keV, but the existing data, coming from an experiment performed in the 90s (Winters. et al.), do not support this. The goal of ARTIE is to resolve this disagreement by improving knowledge of neutron transport in argon. This measurement is crucial for the Deep Underground Neutrino Experiment (DUNE) because it provides a viable means of calibration via a Pulsed Neutron Source (PNS), and allows a deeper understanding of signals and backgrounds for the low energy science program. [Preview Abstract] |
Monday, April 20, 2020 1:54PM - 2:06PM On Demand |
R14.00003: Precision Measurement of the n-$^{235}$U fission cross section using the “Alpha-Gamma” Absolute Cold Neutron Flux Measurement Device. Chris Haddock The Alpha-Gamma device at NIST utilizes the interaction of neutrons with a totally absorbing $^{10}$B target to precisely measure the flux of a monochromatic neutron beam. This measurement provides a calibration of the $^{6}$Li(n,$\alpha$)$^{3}$H based flux monitor used in the NIST neutron lifetime experiment to better than 0.1\% and is now being utilized in a novel measurement of the $^{235}$U neutron-induced fission cross section at the 0.2\% level in an effort to provide a systematically independent measurement greatly needed in the global determination of this quantity. The results of recent and ongoing measurements will be presented, and planned operations will be discussed. [Preview Abstract] |
Monday, April 20, 2020 2:06PM - 2:18PM On Demand |
R14.00004: Precision Measurements of Neutron-Silicon Structure Factors Using Pendell\"{o}sung Interferometry Benjamin Heacock, Michael Huber, Takuhiro Fujiie, Katsuya Hirota, Masaaki Kitaguchi, Hirohiko Shimizu, Takuya Hosobata, Yutaka Yamagata, Dmitry Pushin, Robert Valdillez, Albert Young Neutron dynamical diffraction in a crystal slab exhibits pendell\"{o}sung interference, where the diffracted intensity oscillates as a function of neutron wavelength, crystal thickness, and the neutron-lattice potential. The phase of pendell\"{o}sung oscillations is used to perform precision measurements of the (111), (220), and (400) neutron structure factors in silicon. These data are sensitive to lattice dynamics, the neutron mean square charge radius, and a beyond the standard model of particle physics force mediator with a mass between 10 eV and 10 keV. Preliminary data will be presented, including a new measurement of the neutron charge radius and the silicon Debye-Waller B parameter. Previous experimental limits on the strength of a beyond the standard model force mediator with mass range 10~eV to 10~keV are improved by nearly an order of magnitude over most of the mass range and almost two orders of magnitude for a 25~eV force mediator. Extending the experiment to higher order Bragg reflections and/or other crystal species will be sensitive to anharmonic contributions to lattice dynamics and further improve sensitivity to the neutron charge radius and beyond the standard model forces. [Preview Abstract] |
Monday, April 20, 2020 2:18PM - 2:30PM |
R14.00005: Towards a Meter Scaled Grating Neutron Interferometer for Fundamental Physics Applications MG Huber, P Bajcsy, B Heacock, DS Hussey, P Kienzle, N Klimov, K Weigandt, C Kapahi, DA Pushin, D Sarenac Researchers at NIST in collaboration with the NIH, U. Waterloo and NC State have recently developed a new type of neutron interferometer based on phase gratings and operating in the far field. This phase grating moir\'{e} interferometer (PGMI) consists of 3 independent nanofabricated silicon phase gratings. Because the separation between the gratings is adjustable from centimeters to several meters, the PGMI has the potential to be more phase sensitive than traditional single-crystal neutron interferometers which are limited to \textless 100 centimeters in overall length. The PGMI has the potential to impact many fields including material characterization of microporous structures, study quantum systems, and measure weak potentials. NIST is currently commissioning a new facility devoted to developing a PGMI for fundamental physics applications. To quantify the PGMI's ultimate sensitivity, the facility's first aim is to perform a precision measurement using a strong potential. Namely, that of the Earth's local gravitational field ($g)$. The ultimate goal is to measure $g$ over increasing longer grating separations. [Preview Abstract] |
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