Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session Z14: Neutrinos IV |
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Sponsoring Units: DPF Chair: Young-Kee Kim Room: Sheraton Plaza Court 3 |
Tuesday, April 16, 2019 3:30PM - 3:42PM |
Z14.00001: PROSPECT, the Precision Reactor Oscillation and SPECTrum experiment Xiaobin Lu
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Tuesday, April 16, 2019 3:42PM - 3:54PM |
Z14.00002: Search for Short Baseline Sterile Neutrino Oscillation with PROSPECT Hans P Mumm, Jeremy Gaison The PROSPECT short-baseline reactor experiment is designed to perform a precision measurement of the antineutrino spectrum associated with 235-U and probe, to high-significance, sterile neutrino oscillation with mass states in the eV region. PROSPECT operates at a distance of 7m from the compact high-flux isotope reactor (HFIR) at ORNL and consists of a single volume of 6Li-loaded liquid scintillator separated into 154 optically isolated segments. Segmentation provides simple event localization over a range of baselines within the detector and thus supports a reactor-model independent oscillation search through a relative measurement of energy spectra between segments. This talk will discuss the PROSPECT oscillation analysis and present recent results. |
Tuesday, April 16, 2019 3:54PM - 4:06PM |
Z14.00003: Reactor Neutrino Spectral Distortions Play Little Role in Mass Hierarchy Experiments Daine L. Danielson, Anna C. Hayes, Gerald T. Garvey The Coulomb enhancement of low energy electrons in nuclear beta decay generates sharp cutoffs in the accompanying antineutrino spectrum at the beta decay endpoint energies. It has been conjectured that these features will interfere with measuring the effect of a neutrino mass hierarchy on an oscillated nuclear reactor antineutrino spectrum. However, these sawtooth-like distortions are found to contribute at a magnitude of only a few percent relative to the mass hierarchy-dependent oscillation pattern in Fourier space. In the Fourier cosine and sine transforms, the features that encode a neutrino mass hierarchy dominate by over sixteen (thirty-three) times in prominence to the maximal contribution of the sawtooth-like distortions from the detailed energy spectrum, given 3.2%/√[Evis./MeV](perfect) detector energy resolution. The effect of these distortions is shown to be negligible even when the uncertainties in the reactor spectrum, oscillation parameters, and counting statistics are considered. This result is shown to hold even when the opposite hierarchy oscillation patterns are nearly degenerate in energy space, if energy response nonlinearities are controlled to below 0.5%. |
Tuesday, April 16, 2019 4:06PM - 4:18PM |
Z14.00004: Significant Excess of Electron-Like Events in the MiniBooNE Short-Baseline Neutrino Experiment En-Chuan Huang The latest MiniBooNE oscillation results with 12.84e20 protons on target (POT) of electron neutrino appearance data, doubled from the previous oscillation publication, and 11.27e20 POT of electron antineutrino appearance data will be presented. A 4.7 sigma excess (460.5+/-99.0 events) is observed for a combined analysis with electron neutrino and electron antineutrino events. The observed excess is consistent with the excess reported by the LSND experiment. The best oscillation fit to the excess has a probability of 21.1% in a two-neutrino interpretation, which would require at least one more neutrino type beyond the three-neutrino paradigm. |
Tuesday, April 16, 2019 4:18PM - 4:30PM |
Z14.00005: Event selection of charged current neutrino induced charged Kaon production in the MicroBooNE Varuna N Meddage The MicroBooNE experiment at Fermilab uses a liquid argon time projection chamber (LArTPC) to search for the anomalous production of electron-neutrino like events and to study neutrino-argon cross sections in the ~ 1 GeV energy regime. The neutrino induced kaon production in liquid argon is important in many aspects. First, for a proton decay experiment, the main background of concern is an atmospheric neutrino interacting with the detector medium and producing a kaon, mimicking the proton decay signal of proton decaying to charged kaon and neutrino. The other thing is that there are not many measurement in this channel. Ultimately this new measurement would help to better model the neutrino-argon interactions and hence better understand the neutrino oscillation parameters.In this talk we focus on how we use new tools for particle identification to achieve high purity tagging of neutrino induced charged kaons produced along with a muon in charged current interactions inside the MicroBooNE detector. |
Tuesday, April 16, 2019 4:30PM - 4:42PM |
Z14.00006: Sterile Neutrino Search via Neutral-Current Disappearance with NOvA Michael Wallbank Observations of neutrino oscillations from the majority of neutrino oscillation experiments are consistent with a three-flavor framework. However, the excess of events seen by LSND and MiniBooNE may be incompatible with this model and require an additional, sterile, neutrino to explain these data with neutrino mixing. These intriguing results are not conclusive and are in tension with findings from other short-baseline and long-baseline experiments. |
Tuesday, April 16, 2019 4:42PM - 4:54PM |
Z14.00007: JSNS2: A Sterile Neutrino Search using Appearance at the J-PARC Spallation Neutron Source Nicholas W Kamp The J-PARC Sterile Neutrino Search at the J-PARC Spallation Neutron Source (JSNS2) experiment is being constructed to explore the LSND and MiniBooNE anomalies, possibly indicative of oscillations involving a sterile neutrino. JSNS2, expecting first data in 2019, will use a 17 ton gadolinium-loaded liquid scintillator volume exposed to neutrinos from an eventually 1 MW spallation neutron source at the J-PARC MLF. Like LSND, JSNS2 will predominantly observe antineutrinos from μ+ decay-at-rest in searching for oscillations at high-Δm2. JSNS2 will also measure neutrino-induced nuclear reaction cross sections in the energy range relevant to core-collapse supernovae, and expects to record 10,000 to 20,000 charged current events from kaon decay-at-rest per year. This talk details the unique capabilities of JSNS2 and reports on the status of the detector. |
Tuesday, April 16, 2019 4:54PM - 5:06PM |
Z14.00008: Status of Sterile Neutrino Global Fits Alejandro Diaz, Gabriel Collin, Carlos Argüelles, Janet Marie Conrad, Michael H Shaevitz A number of short-baseline neutrino oscillation experiments have observed anomalous results which are consistent with the existence of a high mass-squared splitting Δm2 ≈ 1 eV2 in the neutrino sector. This would require the existence of at least one additional, sterile, neutrino. At the same time, other experiments have seen null results that strongly constrain the parameters space for the simplest sterile neutrino model. This 3+1 ν model thus faces incompatibilities between these various experiments. We will discuss some recent results in the field of short-baseline oscillation experiments and how they fit into the overall global picture. We will then introduce other models into the global fits, and discuss how they affect the tensions seen. |
Tuesday, April 16, 2019 5:06PM - 5:18PM |
Z14.00009: Searching for Sterile Neutrinos with the Coherent CAPTAIN-Mills Detector at the Los Alamos Neutron Science Center Richard G Van de Water The MiniBooNE and LSND experiments have shown compelling evidence for sterile neutrinos in short baseline neutrino oscillation experiments. In these experiments, an excess of electron neutrino appearance was observed from a pure muon neutrino beam, and if these data are interpreted as sterile neutrino oscillations, the mass scale is ~1 eV2. Analogous muon neutrino disappearance measurements have shown no anomalies, but these experiments have been performed at a different energy scale compared to LSND and MiniBooNE. Coherent CAPTAIN-Mills (CCM) is a new experiment to search for muon neutrino disappearance at the LSND energy scale. CCM will use a 10-ton liquid argon scintillation detector to leverage the enhanced cross section from coherent elastic neutrino-nucleus scattering. CCM will operate at the Lujan Center at LANSCE which is a 100-kW stopped pion source that delivers an 800-MeV proton beam onto a tungsten target at 20 Hz with a pulse width of 290 ns. This fast pulsing is crucial for isolating the monoenergetic muon neutrino in time and reducing neutron backgrounds. In this talk, I will describe the current state of sterile neutrinos, describe the CCM detector and the Lujan Center, and show first results from our successful Fall 2018 commissioning run. |
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