Bulletin of the American Physical Society
2012 Fall Meeting of the APS Division of Nuclear Physics
Volume 57, Number 9
Wednesday–Saturday, October 24–27, 2012; Newport Beach, California
Session PF: Neutrino Oscillations and Underground Physics |
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Chair: Dinko Pocanic, University of Virginia Room: Garden III |
Saturday, October 27, 2012 10:30AM - 10:42AM |
PF.00001: Implications of the recently measured, surprisingly large value of $\theta_{13}$ Bernadette Cogswell, Hunter Burroughs, Jesus Escamilla-Roa, David Latimer, David Ernst The reactor experiments RENO, Daya Bay, and Double Chooz have recently measured a statistically significant non-zero value of $\theta_{13}$. The implications of this result for determining the hierarchy and the sign of $\theta_{13}$ will be examined by performing an analysis that includes these reactor experiments, appearance and disappearance experiments from MINOS and T2K, and atmospheric data. The study is done in the context of the broken symmetry that produces degeneracy for the MINOS and T2K disappearance experiments, the symmetry of the simultaneous interchange of hierarchy and the sign of $\theta_{13}$. Results will be presented utilizing a new approach for extracting error bars and probabilities that does not assume normal statistics. In particular, the probability the correct solution for each of the four combinations of hierarchy and the sign of $\theta_{13}$ will be given. [Preview Abstract] |
Saturday, October 27, 2012 10:42AM - 10:54AM |
PF.00002: Neutrino Scattering and Flavor Transformation in Supernovae John Cherry, Joseph Carlson, Alexander Friedland, George Fuller, Alexey Vlasenko We show that the small fraction of neutrinos that undergo direction-changing scattering outside of the neutrinosphere could have significant influence on neutrino flavor transformation in core-collapse supernova environments. The flux of these scattered neutrinos is strongly dependent on the nuclear composition of the supernova envelope, and as a result the neutrino flavor evolution history may also be dependent on nuclear composition. We demonstrate that the standard treatment for collective neutrino flavor transformation is adequate at late times, but could be inadequate in early epochs of core-collapse supernovae, where the potentials that govern neutrino flavor evolution are affected by the scattered neutrinos. Taking account of this effect, and the way it couples to entropy and composition, will require a new approach in neutrino flavor transformation modeling. [Preview Abstract] |
Saturday, October 27, 2012 10:54AM - 11:06AM |
PF.00003: Searching for Lorentz Violation with Reactor Antineutrinos Joshua Spitz Neutrino oscillations are a sensitive probe of Lorentz violation. The Double Chooz neutrino oscillation experiment's exploration of this phenomenon is presented. Sensitivity to Lorentz violation is provided through a search for a sidereal modulation of the observed signal. The extracted measurements represent the first limits on a number of Lorentz violating parameters; specifically, the parameters associated with transitions between electron and tau flavor. This analysis is the first test of Lorentz invariance using a reactor-based antineutrino source. [Preview Abstract] |
Saturday, October 27, 2012 11:06AM - 11:18AM |
PF.00004: OscSNS: A Precision Short-Baseline Neutrino Oscillation Experiment William Louis Short baseline neutrino experiments are consistent with neutrino oscillations at a $\Delta m^2$ of approximately 1 eV$^2$, and world neutrino and antineutrino data fit reasonably well to a 3+N (active+sterile) neutrino oscillation model with CP violation. The OscSNS experiment at ORNL would be able to make precision short-baseline neutrino oscillation measurements and prove that sterile neutrinos exist by observing oscillations of a neutral current reaction in the detector. The OscSNS experiment will be described and the corresponding neutrino oscillation sensitivities and signals will be discussed. [Preview Abstract] |
Saturday, October 27, 2012 11:18AM - 11:30AM |
PF.00005: Latest results from a search for $\nu_\mu \rightarrow \nu_e$ and $\overline{\nu}_\mu \rightarrow \overline{\nu}_e$ with the MiniBooNE Experiment Rex Tayloe The MiniBooNE experiment, located at Fermilab on the Booster Neutrino Beamline, has searched for $\nu_\mu \rightarrow \nu_e$ and $\overline{\nu}_\mu \rightarrow \overline{\nu}_e$ oscillations in the range $0.1<\Delta m^2<5.0$~ev$^2$ as indicated by results from the LSND experiment. MiniBooNE has recently completed $\overline{\nu}_{\mu}$ running after collecting $11.3 \times 10^{20}$ protons-on-target (POT). Combining those results with previously collected $\nu_\mu$ data from $6.5 \times 10^{20}$ POT yields a $3.8\sigma$ excess over background, consistent with that expected from the LSND result. These results will be presented along with plans for continued data collection with MiniBooNE. [Preview Abstract] |
Saturday, October 27, 2012 11:30AM - 11:42AM |
PF.00006: Status of the Project 8 Detector Prototype Jared Kofron Efforts to measure the electron neutrino mass require measuring a distortion in the beta decay spectrum produced by the kinematics of the 3 body decay. The Project 8 experiment employs a novel approach to electron energy measurement using radio frequency techniques which promises a unique combination of scalability, superb resolution, and low background. A beta decay electron trapped in a strong magnetic field will emit cyclotron radiation (27 Ghz at B=1T), where the frequency of that cyclotron radiation depends on the total energy of the electron due to relativistic effects. Therefore, observing the emitted radiation provides a non-destructive method for measuring the total electron energy and therefore determining the neutrino mass. Results from a prototype experiment in which $^{83m}$Kr is used as an electron source will be presented, as well as an estimate of the sensitivity acheivable with this technique. Project 8 research is supported in part by the Department of Energy. [Preview Abstract] |
Saturday, October 27, 2012 11:42AM - 11:54AM |
PF.00007: Recent results from the SciBath detector at Fermilab R.L. Cooper, L. Garrison, L. Rebenitsch, R. Tayloe, R.T. Thornton The SciBath detector is an 80 liter liquid scintillator detector read out by a three dimensional grid of 768 wavelength-shifting fibers. The fiber readout allows SciBath to measure neutral particle fluxes by tracking the recoiling charged particles with uniform efficiency in all directions. Near 1 MeV, neutrons are detected with 30\% efficiency and 30\% energy resolution, and near 100 MeV, the efficiency is 10\% with a 60\% energy resolution. Recently, a series of measurements were conducted at Fermilab in order to measure neutron backgrounds. At the end of December, a measurement was completed 100 meters underground at the MINOS near-detector area. In support of a possible coherent neutrino scattering experiment, a second measurement was completed in April at the MI-12 target building for the Booster Neutrino Beam. The latest results from both of these measurements will be presented. In addition, an overview of detector performance, with a particular emphasis on the event topology reconstruction, will also be presented. These results can be extrapolated to future measurements of fast-neutron backgrounds at other underground facilities. [Preview Abstract] |
Saturday, October 27, 2012 11:54AM - 12:06PM |
PF.00008: Installation of a simple muon veto for HPGe low background counting at the LBNL Low Background Facility Keenan Thomas, Erick Norman, Alan Smith, Yuen-Dat Chan The Low Background Facility (LBF) at the Lawrence Berkeley National Laboratory (LBNL) performs low level counting of primordial radioisotope concentrations (U, Th, K) and neutron activation analysis for a variety of experiments and users. Many materials characterized at the facility are candidate construction materials for underground, low background experiments which require high standards of radio-purity within detector components. At the LBF, HPGe detectors are used at two unique sites to perform gamma assay: a local low background surface lab at LBNL and an underground site (600 ft. overburden) in Oroville, CA. Since the primary limitation in sensitivity at the surface location is presented by cosmic ray muons, a simple plastic scintillator system has been installed above a HPGe detector as a veto to lower the background continuum due to these events. This talk will summarize the installation and improvement of the system due to this upgrade and provide a general overview of the services that are available at the Low Background Facility. [Preview Abstract] |
Saturday, October 27, 2012 12:06PM - 12:18PM |
PF.00009: Backgrounds from muon-induced spallation in underground detectors Weishi Li Cosmic ray muons induce spallation reactions (nuclear breakups) when passing through underground detectors. For example, subsequent beta decays can lead to detector backgrounds that mimic neutrino signals, and isotopes with long lifetimes are especially difficult to cut. In a recent paper from Super-Kamiokande collaboration, a correlation between the eventual spallation event position and a peak in the prior muon Cherenkov light profile was found. We calculate the rates and properties of electromagnetic showers induced by muons in the Super-Kamiokande detector and the subsequent spallation products, and compare these to data. A better theoretical understanding of these processes will help in developing new techniques to reduce detector backgrounds. [Preview Abstract] |
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