Bulletin of the American Physical Society
APS April Meeting 2021
Volume 66, Number 5
Saturday–Tuesday, April 17–20, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session Y13: Mini-Symposium: Neutrino Properties: New Developments, Challenges and Impacts IILive Mini-Symposium
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Sponsoring Units: DNP Chair: Lisa Kaufman, SLAC |
Tuesday, April 20, 2021 1:30PM - 2:06PM Live |
Y13.00001: Neutrino masses and interactions – a theory perspective Invited Speaker: Zahra Tabrizi Neutrinos are the most mysterious particles of the Standard Model (SM). Some of the neutrino properties can be well described within the SM; however, there are still unanswered questions in the neutrino sector which need to be clarified. How many neutrino species do we have? Are there any CP-violating phase in the neutrino sector? What are the absolute neutrino masses? A general introduction will be given on the current status of the neutrino physics, e.g. sterile neutrinos, neutrino masses, lepton number violation etc. We will also talk about how to systematically study physics beyond the standard model (BSM) in the neutrino oscillation experiments within the standard model Effective Field Theory (SMEFT) framework. In this way, the analysis of the data can capture large classes of models, where the new degrees of freedom have masses well above the relevant energy for the experiment. Moreover, it allows to compare several experiments in a unified framework and in a systematic way. The approach will be applied to several short- and long baseline neutrino experiments. We will show the results of these EFT searches at the Daya Bay and RENO experiments as well as FASERv. [Preview Abstract] |
Tuesday, April 20, 2021 2:06PM - 2:18PM Live |
Y13.00002: The Impact of a New Evaluation of Isomeric Yield Ratios on Reactor Antineutrino Summation Calculations C.J. Sears, E.A. McCutchan, A. Mattera, A.A. Sonzogni The number of isomeric fission yield (IFY) experimental data points available has increased five-fold since the development of the Madland-England Model, the current standard model for estimating IFY ratios. The previous evaluation of isomeric yields over twenty years ago determined this model is generally consistent with the available data from thermal neutron-induced fission of U-235, but a broader analysis has since been called for. In pursuit of a more comprehensive understanding of isomeric yield ratios, all currently available IFY ratio values, for all target nuclei and incident particles, were extracted from the EXFOR database. An evaluation was performed to produce a list of recommended experimental IFY ratios. The recommended values were used to conduct an analysis of the Madland-England model and an attempt was made to draw connections between the model’s parameters and nuclear structure. The data does not suggest any particular correlation between the parameters and any basic observables of the fission fragments. The new yields were used as input to reactor antineutrino summation calculation. Their impact on the antineutrino flux, as well as a sensitivity study to determine the yields which should be improved through new measurements, will be presented. [Preview Abstract] |
Tuesday, April 20, 2021 2:18PM - 2:30PM Live |
Y13.00003: Searching for keV-scale Neutrinos in $^7$Be Decay with the BeEST Experiment Kyle Leach Sterile neutrinos - unlike the active neutrinos in the SM - do not interact with normal matter as they move through space, and their existence is best probed via momentum conservation with SM particles in radioactive decay. 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 a powerful method for BSM neutrino mass searches since it relies only on the existence of a heavy neutrino admixture to the active neutrinos - a generic feature of neutrino mass mechanisms - and not on the model-dependent details of their interactions. In this talk, we will describe the Beryllium Electron capture in Superconducting Tunnel junctions (BeEST) concept, which measures the eV-scale radiation that follows the decay of $^7$Be ions implanted into sensitive, high-rate quantum sensors. We will also report the first results in our experimental program, and future work to increase sensitivity. [Preview Abstract] |
Tuesday, April 20, 2021 2:30PM - 2:42PM Live |
Y13.00004: The First Result on the BeEST keV-scale Sterile Neutrino Search Geon-Bo Kim The BeEST experiment is a direct search for keV-scale sterile neutrinos using $^7$Be atoms that are implanted into superconducting tunnel junction (STJ) detectors. The two-body electron capture decay of $^7$Be produces a neutrino and a $^7$Li nucleus whose momenta and energies are uniquely determined by the mass of the emitted neutrino. We modeled the eV-scale $^7$Be decay spectrum using Voigt and Gaussian functions for $^7$Li recoil peaks, Levinger functions for atomic shaking effects, exponentially modified Gaussian functions for Auger-electron escape, and exponential functions for gamma-ray background events in the substrate. Parameters for nuclear and atomic processes are used to constrain the model shape. We applied a statistical method using the modeled spectral shape and experimental data to find evidence of keV-scale neutrino emission that results in a shift of the $^7$Li recoil peaks in the spectrum. In this talk, we present results of the statistical analysis for the first physics run data obtained with a single-pixel STJ detector, which improves current exclusion limits on keV-scale neutrinos by an order of magnitude. We will also discuss projected sensitivities of next-phase experiments including 10,000-pixel STJ detector arrays with improved energy resolution. [Preview Abstract] |
Tuesday, April 20, 2021 2:42PM - 2:54PM Live |
Y13.00005: Superconducting Tunnel Junction Quantum Sensors for the BeEST Experiment Stephan Friedrich The BeEST experiment searches for a keV sterile neutrino signal in the electron capture decay of $^7$Be that is implanted into superconducting tunnel junction (STJ) quantum sensors. STJs consist of two superconducting films separated by a thin insulating tunnel barrier. They exploit the small ~meV energy gap in superconductors to be sensitive to phonons from the recoiling $^7$Li daughter and to provide an energy resolution of a few eV FWHM for recoil energies below 100 eV. Since the $^7$Li recoil energy depends on the mass of the emitted neutrino, the high resolution can be used to separate a hypothetical sterile neutrino signal from the recoils for decay channels with active neutrinos. In addition, STJs stand out among superconducting quantum sensors for their fast signal decay, which enables STJ operation at several 1000 counts/s per pixel and makes them ideally suited for this high-sensitivity search. This talk will show the design and performance of current STJ detectors – which were initially developed for astronomy and material science in the 1990s – in the BeEST experiment. We will also discuss ongoing STJ development to improve energy resolution and sensitivity of the BeEST sterile neutrino search by several orders of magnitude. [Preview Abstract] |
Tuesday, April 20, 2021 2:54PM - 3:06PM Live |
Y13.00006: Lorentz Violation in Neutrino Oscillations using IceCube Atmospheric Neutrino Interferometry Barbara Skrzypek, Carlos Arguelles Delgado Lorentz invariance is a fundamental symmetry of spacetime underpinning general relativity and the Standard Model of particle physics. However, its violation at high energies could indicate new physics such as string theory or non-commutative field theory. Moreover, as another indication of new physics, neutrino oscillations are a phenomenon that cannot be accommodated within the the Standard Model. Whereas this is usually accounted for by a mass term, Lorentz violating effects could play a subleading role in neutrino oscillations and explain anomalous measurements. Lorentz violation (LV), as formalized in the Standard Model Extension (SME) framework, introduces terms whose characteristic oscillation lengths become significant at atmospheric neutrino energies accessible by the IceCube Neutrino Observatory, providing the most stringent bounds on LV operators. We carry out our LV analysis by using ten years of through-going muon data to study muon-neutrino disappearance in the atmospheric neutrino spectrum at IceCube. We also consider an astrophysical component, which provides a unique and very sensitive test of Lorentz symmetry. In this talk, I will present the current limits on LV by IceCube and sensitivities for our new ten-year analysis. [Preview Abstract] |
Tuesday, April 20, 2021 3:06PM - 3:18PM Live |
Y13.00007: Enabling optical readout in the high-pressure gas TPC (HPgTPC) of DUNE's ND-GAr near detector Diego Gonzalez-Diaz The usage of optical information is ubiquitous in neutrino detectors,~essential for spill-assignment, background suppression and triggering. Enabling an independent and complete physics program at the ND-GAr~component of DUNE's near detector suite will undoubtedly benefit from this feature,~too. We discuss in this presentation the prospects towards simultaneous readout of ionization and scintillation signals in ND-GAr and the R{\&}D~currently performed in this direction. [Preview Abstract] |
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