Bulletin of the American Physical Society
85th Annual Meeting of the APS Southeastern Section
Volume 63, Number 19
Thursday–Saturday, November 8–10, 2018; Holiday Inn at World’s Fair Park, Knoxville, Tennessee
Session E03: Fundamental Symmetries I |
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Chair: Jason Fry, University of Virginia Room: Holiday Inn Knoxville Downtown Parlor |
Friday, November 9, 2018 8:30AM - 8:42AM |
E03.00001: Update on the BL2 in-beam measurement of the neutron lifetime Jimmy Caylor Neutron beta decay is the simplest example of semi-leptonic decay. A precise measurement of the neutron lifetime, as well as the coupling constant λ allows for a determination of the CKM matrix element Vud that is free from nuclear structure effects. The neutron lifetime provides an important test of unitarity and consistency of the Standard Model. The neutron lifetime is also the largest uncertainty in Big Bang Nucleosynthesis calculations of light element abundance. There is currently a large discrepancy between different experimental methods of measuring the neutron lifetime. A new measurement of the neutron lifetime using the in-beam method is ongoing at the NIST Center for Neutron Research. This method requires the absolute counting of the decay protons in a neutron beam of precisely known flux. Improvements in the neutron and proton detection systems as well as the use of a new analysis technique should permit an overall uncertainty of 1s. The experimental status, technical improvements, analysis techniques and early data will be presented. |
Friday, November 9, 2018 8:42AM - 8:54AM |
E03.00002: Proposed Detector Efficiency Calibration Apparatus for use in Neutron Lifetime Measurements Grant V Riley, Nadia Fomin This talk discusses a new proposed method to measure the proton detector efficiency for use in "beam" determinations of the free neutron lifetime. There is currently a 4 sigma disagreement between the "beam" and "storage" methods of measuring the lifetime of the neutron. A possible reason for this is a systematic uncertainty that is not properly accounted for in one or both types of experiments. Absolute proton counting is an essential facet of the "beam" experimental approach. The absolute detector efficiency is not currently known for existing experiments and could be a source of a hidden systematic error. This proposed absolute calibration technique can also be extended to new, large area particle detectors designed for future experiments. |
Friday, November 9, 2018 8:54AM - 9:06AM |
E03.00003: The Nab spectrometer at Oak Ridge National Lab, and Free Neutron Beta Decay Stefan Baessler Nab, an experiment that allows studying unpolarized neutron beta decay at the Spallation Neutron Source at Oak Ridge National Lab, aims to determine a, the neutrino-electron correlation coefficient, and b, the Fierz interference term, with high precision. Such measurements provide opportunities to search for evidence of extensions to the Standard Model. In the past year, installation of the spectrometer has started in earnest at the Spallation Neutron Source. I will discuss the experiments motivation and design, and report on installation progress. |
Friday, November 9, 2018 9:06AM - 9:18AM |
E03.00004: The Electrode System in the Neutron Decay Region of the Nab Experiment Huangxing Li The Nab collaboration will determine two parameters in free neutron beta decay: (a) the electron-antineutrino correlation coefficient a to Δa/a<10-3 and (b) the Fierz interference term b to Δb<3×10-3. Part (a) will be done with a measurement of the two-dimensional electron energy and proton time-of-flight spectrum in the neutron beta decay. To achieve the desired experimental uncertainty we have certain requirements for the electric field in the neutron decay region. We will present our electrode system made from materials with low work function variations for the decay region, and the work function characterization result from Kelvin Probe. |
Friday, November 9, 2018 9:18AM - 9:30AM |
E03.00005: Optimization and Characterization of Particle Energy and Arrival Time Determination using GPUs for the Nab Experiment David E Perryman Measurements of neutron beta decay correlation parameters yield a ratio of axial and vector weak couplings as well as test physics beyond the Standard Model. The Nab (Neutron a b) experiment will extract these parameters by coincidence detection of beta decay's protons and electrons, which includes energy and time of flight determination. Because of the experiment's expected high data throughput in the form of digitized waveforms from pixelated silicon detectors, it is important to extract energies and times quickly and reliably. This talk will present results from timing and statistical studies using graphics processor based energy and time extraction. |
Friday, November 9, 2018 9:30AM - 9:42AM |
E03.00006: Pile-Up Waveform Filter for the Nab Experiment Ryan A Whitehead The Nab experiment is measuring the electron-neutrino correlation term, along with |
Friday, November 9, 2018 9:42AM - 9:54AM |
E03.00007: Progress of the 45Ca beta spectrum measurement at Los Alamos National Laboratory Noah Birge The Standard Model describes fundamental particle interactions to high precision; however, neutrino flavor oscillations, the observed baryon asymmetry, and complete absence of gravity from the model make it clear that there exists important physics which the model does not describe: so called beyond the standard model (BSM). The Fierz interference term for beta decay is one such observable sensitive to exotic scalar/tensor currents motivated by several BSM theories. A nonzero measurement of the Fierz term essentially manifests in the form of a distortion of the beta decay electron energy spectrum. 45Ca is a particularly appealing nucleus to attempt a measurement of the interference term, as it is an allowed, pure ground state to ground state, beta emitter. A measurement was performed at Los Alamos National Lab in 2017. A brief overview of the experiment along with some preliminary waveform data analyses will be presented. |
Friday, November 9, 2018 9:54AM - 10:06AM |
E03.00008: Let there be light... and flux quanta: anticipating the first signals from nEDM@SNS Kent KH Leung The neutron electric dipole moment (nEDM) experiment at the Spallation Neutron Source (SNS) of ORNL will improve the currently best world-wide nEDM limit by two-orders-of-magnitude by performing high-precision nuclear magnetic resonance simultaneously on polarized ultracold neutrons and polarized 3He in a 3 L bath of 0.4 K superfluid helium. In order to reach this unprecedented precision, a novel scheme combining techniques from nuclear and particle physics as well as atomic, molecular and optical physics will be used. |
Friday, November 9, 2018 10:06AM - 10:18AM |
E03.00009: Magnetic Field Design for Spin Transport in the SNS nEDM Experiment Mark H McCrea Measurements of the neutron electric dipole moment (nEDM) are one of the most important tests of the parity and time reversal symmetries with implications both to baryogenesis in the early universe and fundamental physics. The SNS nEDM experiment aims to make a measurement to an accuracy of $4\times10^{-28}$ e-cm, 100 times better than previously existing measurements that have only set an upper limit on the value of the nEDM. This experiment requires a uniform magnetic field around the measurement volume, and the transport of the polarized He-3 into the measurement volume. I will talk about the magnetic field design for the magnetic shielding room that will house the experiment, and the design of the additional magnets that are used for the transport of polarized He-3 into the measurement volume while maintaining the uniformity of the magnetic fields in the interior of the magnetic shielding room. |
Friday, November 9, 2018 10:18AM - 10:30AM |
E03.00010: COHERENT Search for Neutrino-Induced Neutrons at the Spallation Neutron Source Brandon J Becker Neutrino-nucleus interactions serve as a possible probe to study the nucleus and weak interactions. The COHERENT Collaboration seeks to observe the N2 dependence of the coherent elastic neutrino-nucleus scattering (CEvNS) and continues taking data for the precision measurement of the CEvNS cross-section for multiple nuclei. A large effort has been dedicated to understanding backgrounds present, and perhaps the most dangerous is the background arising from inelastic neutrino-nucleus interactions in the detector shielding. Inelastic neutrino-nucleus interactions excite a nucleus that then de-excite by neutron emission. Such neutrons can interact in a detector and produce nuclear recoils that mimic nuclear recoils produced by CEvNS and also share the same timing distribution as CEvNS events. The cross-section for heavy nuclei such as Lead and Iron is predicted to be quite large but has not been measured and theoretical calculations have large uncertainty. Lead is of particular interest because it is major component of the HALO Supernovae Neutrino detector. The COHERENT Collaboration is constructing and characterizing capture-gated neutron detectors for deployment in 980 kg of lead target to measure the inelastic neutrino-nucleus cross-section in Pb-208. |
Friday, November 9, 2018 10:30AM - 10:42AM |
E03.00011: Using Vector Boson Fusion Processes to Understand Particles and Interactions at TeV Scales Andres Florez, Alfredo Gurrola, Will Johns, Teruki Kamon, Klaas Padeken, Paul Sheldon, Savanna Rae Starko For decades, physicists have relied on the Standard Model (SM) as a cohesive explanation of how particles and forces relate. Though the SM has agreed with countless experimental observations, it still fails to answer some fundamental questions in physics. Development of theories that incorporate additional interactions is an attempt to address shortcomings of the SM. A shared characteristic of these theories is the manifestation of new particles with TeV scale masses that can be probed by collider experiments. Focus of this research is on the search for new heavy gauge bosons produced inside the CMS experiment at the LHC by targeting a rare, distinct production mechanism called Vector Boson Fusion (VBF). Focus is on a VBF-produced Z', which decays to a pair of W bosons that decay leptonically to an electron and muon. Current work consists of developing a data-driven methodology to determine contributions from SM backgrounds in the signal region. This study will investigate how efficiently the experiment can identify the pair of jets characteristic of a VBF process in the forward regions of the detector. The integrated luminosity of pp data collected by CMS will allow this analysis to achieve discovery reach for Z' masses out to 2 TeV. |
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