Bulletin of the American Physical Society
APS April Meeting 2017
Volume 62, Number 1
Saturday–Tuesday, January 28–31, 2017; Washington, DC
Session C4: Neutrinos - Instruments, Science and Modeling |
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Sponsoring Units: DAP Chair: Justin Vandenbrouke, University of Wisconsin Room: Virginia A |
Saturday, January 28, 2017 1:30PM - 1:42PM |
C4.00001: The Askaryan Radio Array: Overview and Recent Results Carl Pfendner The Askaryan Radio Array (ARA) is radio frequency observatory under construction at the South Pole that is searching for ultrahigh energy neutrinos via the Askaryan effect. By instrumenting several gigatons of Antarctic glacial ice, the experiment aims to detect a flux of neutrinos above 10 PeV in energy. The measurement of this expected flux of neutrinos would provide information about the highest energy processes in the universe with no local horizon. The full detector consisting of 37 stations is being constructed in a phased deployment with 3 stations already in place and two more planned for deployment in the 2017-2018 season. Recent results from an analysis of data from two stations and a search for neutrinos correlated with gamma ray bursts are presented here. [Preview Abstract] |
Saturday, January 28, 2017 1:42PM - 1:54PM |
C4.00002: Searching for Traces of Planck-Scale Physics with High Energy Neutrinos Floyd Stecker, Sean Scully, Stefano Liberati, David Mattingly Some Planck-scale physics and quantum gravity models predict a slight violation of Lorentz invariance (LIV) at high energies. High-energy cosmic neutrino observations can be used to test for such LIV. Operators in an effective field theory (EFT) can be used to describe the effects of LIV. They can be used to calculate kinematically allowed energy losses of possible superluminal neutrinos. These losses can be caused by both vacuum pair emission (VPE) and neutrino splitting. Assuming a reasonable distribution of extragalactic neutrino sources, we determined the resulting after-loss neutrino spectra using Monte Carlo propagation calculations. We then compared them with the neutrino spectrum observed by IceCube to determine the implications of our results regarding Planck-scale physics. If the drop off in the observed IceCube neutrino flux above 2 PeV is caused by LIV, a potentially significant pileup effect would be produced just below the drop-off energy in the case of CPT-even operator dominance. However, such a clear drop off effect would not be observed if a CPT-odd, CPT-violating term dominates. [Preview Abstract] |
Saturday, January 28, 2017 1:54PM - 2:06PM |
C4.00003: Using the Enhanced Starting Track Event Selection to Improve IceCube's Measurement of Neutrinos From the Southern Hemisphere Kyle Jero The IceCube analyses that identify the astrophysical neutrino flux from the southern hemisphere must reject muons and neutrinos from the atmosphere. To do this, the analyses use the outer regions of the detector to identify and reject penetrating muon tracks produced by cosmic ray interactions with the atmosphere. By doing so they can remove atmospheric neutrinos and muons. By using the outer regions of the detector the analyses must also reduce the fiducial volume to the inner part of the detector. Here we will discuss a method that is optimized for finding muon neutrinos with a contained vertex. This selection utilizes the high quality directional information of muons to veto through-going events on a case by case basis. Once a direction and vertex have been determined, the likelihood for not seeing a hit on digital optical modules (DOMs) passed by the incident neutrino can be calculated based on the observed hits. This opens most of the instrumented volume up for neutrino detection. The results of this technique will provide identifiable astrophysical neutrinos above 10 TeV originating from the southern. This region is interesting for galactic sources and currently has the weakest sensitivity to neutrino point sources. Expectations from an initial data sample and simulation assuming potential diffuse and galactic fluxes will be shown. In addition to aiding in the understanding interesting southern sky sources, these new events can also assist in providing insight to astrophysical neutrino flavor ratios and the diffuse astrophysical flux. [Preview Abstract] |
Saturday, January 28, 2017 2:06PM - 2:18PM |
C4.00004: Uncertainties in Atmospheric Muon-Neutrino Fluxes Arising from Cosmic-Ray Primaries Salvatore Davide Porzio, Justin Evans, Stefan Soldner-Rembold, Steven Wren We present an updated calculation of the atmospheric muon-neutrino flux uncertainties arising from cosmic-ray primaries, including for the first time the information from recent measurements of the cosmic-ray primaries. We apply a statistical technique that allows the determination of correlations between the parameters of the GSHL primary-flux parametrisation, and the incorporation of these correlations into the uncertainty on the muon-neutrino flux. Given the unexpected hardening of the spectrum of primaries above 100 GeV observed in recent measurements, we propose an alternative parametrisation and discuss its impact on the neutrino flux uncertainties. We obtain an uncertainty on the primary cosmic-ray component of $\approx (5\text{-}10)\%$, depending on energy, which is a about a factor of two smaller than for the previous fit. The hadron production uncertainty is added in quadrature to obtain the total uncertainty on the neutrino flux. [Preview Abstract] |
Saturday, January 28, 2017 2:18PM - 2:30PM |
C4.00005: Muon-induced spallation backgrounds in DUNE Guanying Zhu, Shirley Li, John Beacom Galactic supernovae are rare, just a few per century, so it is important to be prepared. If we are, then the long-baseline detector DUNE could detect thousands of events, compared to the tens from SN 1987A. An important question is backgrounds from muon-induced spallation reactions. We simulate particle energy-loss processes in liquid argon, and compare relevant isotope yields with those in the water-Cherenkov detector SuperK. Our approach will help optimize the design of DUNE and further benefit the study of supernova neutrinos. [Preview Abstract] |
Saturday, January 28, 2017 2:30PM - 2:42PM |
C4.00006: Presupernova neutrinos: realistic emissivities from stellar evolution Kelly Patton, Cecilia Lunardini, Rob Farmer, Frank Timmes We present a calculation of neutrino emissivities and energy spectra from a presupernova, a massive star going through the advanced stages of nuclear burning before becoming a supernova. Neutrinos produced from beta decay and electron capture, as well as pair annihilation, plasmon decay, and the photoneutrino process are included. We use the state of the art stellar evolution code MESA to obtain realistic conditions for temperature, density, electron fraction, and nuclear isotopic composition. We have found that beta processes contribute significantly to the neutrino flux at potentially detectable energies of a few MeV. Estimates for the number of events at several current and future detectors are presented for the last few hours before collapse. [Preview Abstract] |
Saturday, January 28, 2017 2:42PM - 2:54PM |
C4.00007: Analysis of North Sky Cosmic Ray Anisotropy with Atmospheric Neutrinos Elizabeth Wills Since the discovery of Cosmic Ray anisotropy, no experiment has definitively discovered the source of this unexpected phenomenon. Studying the cosmic rays' neutral daughter particles with pointing capabilities, like neutrinos, could shed new light. This can be done at two levels; a source which produces cosmic rays must also produce high energy astrophysical neutrinos, and low energy atmospheric neutrinos are made when the cosmic rays interact with the atmosphere. This analysis focuses on atmospheric neutrinos detected by IceCube, a Cherenkov detector instrumenting a kilometer cubed of glacial ice at the South Pole. The anisotropy and its energy dependence have been studied in the Southern sky using atmospheric muons by IceCube. In the North, gamma ray detectors, such as HAWC, and Argo-YBJ, have observed this anisotropy in cosmic ray showers. Thus far, no single- detector full-sky map exists of the anisotropy. Using IceCube's neutrino data, we can complement these studies with an exploration of the northern sky anisotropy at higher energies of cosmic rays. This could bring us much closer to understanding the complete picture of this anisotropy across energy levels and the whole sky. [Preview Abstract] |
Saturday, January 28, 2017 2:54PM - 3:06PM |
C4.00008: Search for PeV Gamma Rays with IceTop and IceCube Zachary Griffith, Hershal Pandya Gamma-ray induced air showers produce muons at a rate much lower than hadronic air showers. Therefore, air showers detected by the surface array IceTop that pass through the underground muon detector IceCube can be effectively separated into photons and hadrons by utilizing the presence of IceCube signal. As the threshold for muon detection in IceCube is around 500 GeV, this veto becomes effective at close to PeV primary energies. We present results of a search for PeV gamma rays with IceTop and IceCube, including a search for point sources, correlations with TeV sources detected by H.E.S.S., neutrino events from IceCube's high energy starting event sample, and the Galactic plane. [Preview Abstract] |
Saturday, January 28, 2017 3:06PM - 3:18PM |
C4.00009: Constraining Dark Matter-Neutrino Interactions with High-Energy Astrophysical Neutrinos Carlos Arguelles IceCube has continued to observe cosmic neutrinos since their discovery. The origin of these cosmic neutrinos is still unknown. Moreover, their arrival direction is compatible with an isotropic distribution. The this observation, together with dedicated studies looking for galactic plane correlations, suggest that the observed astrophysical neutrinos are of extragalactic origin. If there is a dark matter-neutrino interaction, then the observed neutrino flux and its spatial distribution would be distorted. We perform a likelihood analysis using four years of IceCube's high energy starting events to constrain the strength dark matter neutrino interactions in the context of simplified models. Finally, we compare our results with cosmology and highlight the complementary between the two constraints. [Preview Abstract] |
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