Bulletin of the American Physical Society
2020 Fall Meeting of the APS Division of Nuclear Physics
Volume 65, Number 12
Thursday–Sunday, October 29–November 1 2020; Time Zone: Central Time, USA
Session DG: Neutrino Interactions I |
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Chair: Jon Engel, UNC |
Friday, October 30, 2020 8:30AM - 8:42AM |
DG.00001: The BeEST Experiment: A Search for keV-Scale Neutrinos in the EC Decay of 7Be with Superconducting Quantum Sensors Kyle Leach The search for sterile neutrinos is among the brightest possibilities in our quest for understanding the microscopic nature of dark matter in our universe. Sterile neutrinos - unlike the active neutrinos in the SM - do not couple to left-handed currents in the weak interaction, and are thus best observed via their mass-generated effects that result from momentum conservation with SM particles. One way to observe these momentum recoil effects experimentally is through high-precision measurements of electron-capture (EC) nuclear decay, where the final state only contains the neutrino and a recoiling atom. This approach is among the most powerful methods for BSM neutrino mass searches since it relies only on the existence of a heavy neutrino admixture to the active neutrinos, which is a generic feature of neutrino mass mechanisms, and not on the model-dependent details of their interactions. In this talk, we report the first measurements in the Beryllium EC STJ (BeEST) experimental program, which uses the decay-momentum reconstruction technique to precisely measure the $^7$Be$\rightarrow^7$Li recoil spectrum via $^7$Be ions implanted into sensitive superconducting tunnel junction (STJ) radiation detectors. [Preview Abstract] |
Friday, October 30, 2020 8:42AM - 8:54AM |
DG.00002: Current limits and projected sensitivities of the BeEST sterile neutrino search Geon-Bo Kim The BeEST experiment is a direct search for keV-scale sterile neutrinos using Be-7 atoms that are implanted into superconducting tunnel junction (STJ) detectors. The two-body electron capture decay of Be-7 produces a neutrino and a Li-7 nucleus whose momenta and energies are uniquely determined by the mass of the emitted neutrino. We accurately measure energies of Li-7 recoils using STJ detectors to look for evidence of keV-scale sterile neutrino emissions that result in decreased recoil energy of Li-7 nuclei. We will present current exclusion limits for keV-scale sterile neutrino mixing from the first physics run with a single-pixel STJ detector, and projected sensitivities of next phase-experiments with improved 128-pixel STJ detector arrays. [Preview Abstract] |
Friday, October 30, 2020 8:54AM - 9:06AM |
DG.00003: Update: Neutrino mass measurements with KATRIN Bjoern Lehnert The Karlsruhe Tritium Neutrino (KATRIN) experiment probes the electron neutrino mass with beta decays, reaching an ultimate sensitivity of 0.2 eV (90% CL). KATRIN performs high-precision spectroscopy of $\beta$-electrons near the tritium endpoint at 18.6 keV by employing a windowless gaseous tritium source and an electrostatic spectrometer based on the MAC-E filter principle. This approach allows a model-independent measurement of the neutrino mass and is complementary to model-dependent measurements with cosmology and neutrinoless double beta decay. The required sensitivity demands high stability of hardware components, precise understanding of systematic effects, and low background. The commissioning of the system was completed in 2019 followed by the first data release. KATRIN accumulated more data in 2020 and investigates different operating modes to further enhance sensitivity. This talk will give an overview of the current status and the latest results. [Preview Abstract] |
Friday, October 30, 2020 9:06AM - 9:18AM |
DG.00004: BEST sterile neutrino search with gallium In Wook Kim The Baksan Experiment on Sterile Transitions (BEST), based on the Gallium-Germanium neutrino telescope (GGNT) of the SAGE experiment, aims to fully explore the Gallium anomaly. As a short-baseline neutrino oscillation experiment, BEST setup is composed of two concentric zones filled with liquid Ga: the inner spherical zone of 0.66 m radius and the outer cylinderical zone of 1.096 m radius and 2.192 m height. A mono-energetic $^{51}$Cr source with activity of 3.4099$\pm$0.008 MCi was placed at the center of the setup. Any deficit in the neutrino capture rates in the two zones, as well as their differences, would directly indicate the existence of neutrino oscillation to a sterile state on a short baseline. The 2-zone target was exposed to the neutrino source 10 independent times from July 5th to Oct. 23rd 2019, and 20 $^{71}$Ge extractions were made from the two Ga targets. The $^{71}$Ge decay rates were measured from July 2019 to March 2020 to count the total production rate of $^{71}$Ge from the neutrino source. In this talk, the experimental details and the status of BEST sterile neutrino experiment will be explained. [Preview Abstract] |
Friday, October 30, 2020 9:18AM - 9:30AM |
DG.00005: Improving Low-Energy GEANT4 Simulations of $^7$Be EC Decay in STJ Detectors for the BeEST Experiment Connor Bray The BeEST Experiment uses Superconducting Tunnel Junctions (STJs) to search for keV-scale sterile neutrinos in the Electron Capture (EC) decay of 7Be. The ultimate sensitivity of this approach is heavily dependent on a precision characterization of the detector response to a wide range of low-energy radiation emitted in the decay. Detailed ultra-low-energy, multi-process particle simulations in GEANT4 are employed to help describe these processes to high accuracy. In this talk, I will present preliminary results and advancements towards accurate meV-scale GEANT4 simulations. [Preview Abstract] |
Friday, October 30, 2020 9:30AM - 9:42AM |
DG.00006: Cosmogenic neutron production at the Sudbury Neutrino Observatory Ed Callaghan Neutrons produced via nuclear interactions by cosmic muons present an irreducible background to many rare event searches, even in detectors located deep underground. We report the observation of collections of neutrons following throughgoing muons at the Sudbury Neutrino Observatory, as well as a measurement of the neutron yield per unit muon track length. Also presented is a set of GEANT4-based Monte Carlo simulations which reproduce characteristic observables of the follower neutrons in relation to the preceding muons. [Preview Abstract] |
Friday, October 30, 2020 9:42AM - 9:54AM |
DG.00007: Sterile neutrinos and neutrinoless double beta decay in effective field theory Guanghui Zhou, Wouter Dekens, Jordy Vries, Kaori Fuyuto, Emanuele Mereghetti I discuss neutrinoless double beta decay (0$\nu \beta \beta )$ in the presence of sterile neutrinos with Majorana mass terms. The gauge-singlet fields are allowed to interact with Standard-Model (SM) fields via renormalizable Yukawa couplings as well as higher-dimensional gauge-invariant operators. I discuss how to use chiral effective field theory involving sterile neutrinos to connect the operators at the level of quarks and gluons to hadronic interactions involving pions and nucleons and how to derive an expression for 0$\nu \beta \beta $ rates. The required hadronic low-energy constants and nuclear matrix elements depend on the neutrino masses, and I present interpolation formulae grounded in QCD and chiral perturbation theory. The resulting framework can be used directly to assess the impact of 0$\nu \beta \beta $ experiments on scenarios with light sterile neutrinos. I demonstrate that non-standard interactions involving sterile neutrinos have a dramatic impact on 0$\nu \beta \beta $ phenomenology, and next-generation \newline experiments can probe such interactions up to scales of O(100) TeV. [Preview Abstract] |
Friday, October 30, 2020 9:54AM - 10:06AM |
DG.00008: Antineutrinos in scintillator at SNO+ Logan Lebanowski SNO+ is a multipurpose neutrino experiment located 2 km underground in a Canadian mine. The primary goal is a high-sensitivity search for neutrinoless double beta decay, however SNO+ is also measuring antineutrinos from nuclear reactors and the local terrain. The nearest reactor complex is located 240 km away and comprises the most powerful set of reactors currently active. At present, the SNO+ detector is approximately half-filled with 370 tonnes of scintillator. We expect to measure the neutrino mass splitting $\Delta m^2_{21}$ with a precision comparable to that of KamLAND, and make the first measurement of a U/Th geo neutrino flux in the Western Hemisphere. [Preview Abstract] |
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