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 D13: Double Beta Decay ILive
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Sponsoring Units: DNP Chair: Vincenzo Cirigliano, LANL |
Saturday, April 17, 2021 1:30PM - 1:42PM Live |
D13.00001: Status of the LEGEND Experiment — Initial Testing and Outlook Eric Martin The Large Enriched Germanium Experiment for Neutrinoless double-beta Decay (LEGEND) experiment is a next generation $^{76}$Ge-based double-beta decay experiment building off the experiences of the {\sc{Majorana}} and GERDA experiments. LEGEND will be implemented in a phased approach. The first phase, LEGEND-200 so named because it consists of 200 kg of $^{76}$Ge enriched germanium, will be deployed in the existing GERDA infrastructure at LNGS. Assembly and testing has already begun. With a background goal of 0.6 counts/FWHM$\cdot$tonne$\cdot$year LEGEND-200 will have a discovery potential of a half-life around 10$^{27}$ years. The proposed second stage, LEGEND-1000 which consists of one-tonne of enriched geranium, could have a discovery potential beyond 10$^{28}$ years. I will give an overview of the initial testing and current status as well as an update on some research and development efforts. [Preview Abstract] |
Saturday, April 17, 2021 1:42PM - 1:54PM Live |
D13.00002: Physics searches beyond neutrinoless double-beta decay with LEGEND-1000 Reyco Henning LEGEND-1000 is a proposed experiment to search for the neutrinoless double-beta decay (NDBD) of the $^{76}$Ge isotope. It will use enriched high-purity germanium (HPGe) detectors deployed in an active liquid argon shield at a deep underground location. The HPGe detectors are based on the p-type point contact detectors successfully demonstrated in \textsc{Majorana} and GERDA. The low noise and low energy thresholds of these detectors, in addition to the low-background design of LEGEND-1000, provides a broad and rich program for searches of new physics other than neutrinoless double-beta decay. Examples include dark matter, axions, exotic nuclear decays, and tests of fundamental symmetries. This talk will review the LEGEND program and describe these other physics opportunities. [Preview Abstract] |
Saturday, April 17, 2021 1:54PM - 2:06PM Live |
D13.00003: nEXO Cleanliness Control Raymond Hei Man Tsang nEXO is a next-generation experiment searching for neutrinoless double beta decay of $^{136}$Xe using a liquid Xe time projection chamber (TPC). It is projected to reach a half-life sensitivity of about $10^{28}$ years with 10 years of exposure time. To achieve this sensitivity, stringent limits on radioactivity are necessary to control backgrounds to a sufficiently low level. While detector construction materials contribute most to the background budget, dust particulates that are deposited on the materials also contribute substantially if they are not properly removed. Specifically, they contribute through their intrinsic U and Th impurities in addition to the out-gassed radon. This talk will discuss our current plans on the estimation, measurement, and mitigation of dust induced backgrounds. [Preview Abstract] |
Saturday, April 17, 2021 2:06PM - 2:18PM Live |
D13.00004: Search for Two-Neutrino Double-Beta Decay of $^{130}$Te to Excited States of $^{130}$Xe with CUORE Erin V. Hansen, Daniel Mayer The CUORE experiment is a ton-scale search for neutrinoless double-beta decay ($0\nu \beta\beta$) composed of an array of 988 tellurium dioxide crystals, each instrumented as a cryogenic macrocalorimeter. While a discovery of $0\nu \beta\beta$ would herald new physics, the Standard Model process of two-neutrino double-beta decay (2$\nu\beta\beta$) in $^{130}$Te is readily measured by CUORE. However, still unobserved in $^{130}$Te are decays wherein the daughter $^{130}$Xe nucleus is left in an excited state which subsequently decays via gamma emission, leading to events with energy deposited across multiple crystals. Understanding the branching ratio and spectral shape for such 2$\nu\beta\beta$ decays to excited states can improve nuclear modelling and help constrain the matrix elements involved in searches for neutrinoless double-beta decay. This work describes progress towards an improved search for 2$\nu\beta\beta$ decays to excited states with an increased exposure of CUORE. By exploiting the segmented nature of the CUORE detector, the scope of event signatures considered in the search is expanded and further accompanied by an improved efficiency of signal containment. [Preview Abstract] |
Saturday, April 17, 2021 2:18PM - 2:30PM Live |
D13.00005: Reconstructing Exotic Track-like Particles with CUORE Julian Yocum The Cryogenic Underground Observatory for Rare Events (CUORE) has played an important role in the search for evidence of neutrinoless double beta decay. However, the experiment also has the capabilities for serving as a detector for exotic track-like particles. Work is done to adapt the CUORE analysis infrastructure for such purposes towards conducting a magnetic monopole search. The segmented nature of CUORE makes the problem of reconstructed track paths non-trivial. This factor has been mitigated through the use of multi-objective optimization, an area of active research in computational techniques involving many cost functions. Such a technique allows the reconstruction of tracks within individual crystals providing crucial track length data which, when correlated with energy data captured by CUORE, allows the calculation of the stopping power of track-like particles. Results are presented which evaluate the precision of the reconstruction tools as they currently stand against Monte Carlo generated data. In addition, current reconstructions of muon events within CUORE are shown. [Preview Abstract] |
Saturday, April 17, 2021 2:30PM - 2:42PM Live |
D13.00006: Overview of the LEGEND-200 Experiment Electronics Rebecca Carney Building on the expertise of the GERDA and {\sc Majorana Demonstrator} experiments, the Large Enriched Germanium Experiment for Neutrinoless double-beta Decay (LEGEND) collaboration is in the process of constructing the first of a two-phased experimental program, LEGEND-200, at Laboratori Nazionali del Gran Sasso in Italy.\\ To reach the design half-life sensitivity, $T_{1/2}^{0\nu} > 1.4\times10^{27}~\textrm{years}$, this $200~\textrm{kg}$ phase of the experiment has high radio-purity, low-noise front-end readout electronics placed close to the germanium detecting volume, read out via purpose-built low mass cables, and processed by dedicated hardware outside the LAr cryostat.\\ This talk will overview the LEGEND-200 electronics chain, from detector readout to digitization, highlighting the unique challenges and possibilities associated with a multi-phase, tonne-scale $0\nu\beta\beta$ solid-state experiment. [Preview Abstract] |
Saturday, April 17, 2021 2:42PM - 2:54PM Live |
D13.00007: Uncertainty Quantification for Neutrinoless Double-Beta Decay Calculations Eduardo Coello Perez Observation of the neutrinoless double-beta decay will unambiguously establish neutrinos as their own antiparticles, shed light on the mechanism giving them mass, and support leptogenesis scenarios for the matter-antimatter asymmetry in the universe. The uncertainty in the nuclear matrix element (NME) governing this process calculated with diverse nuclear models makes it difficult to plan next-generation experiments in search for the decay and to extract precise information from a potential observation. On the other hand, the computational cost of state-of-the art \textit{ab-initio} calculations inhibits an assessment of the uncertainty in the resulting NME. Employing a surrogate model to describe the nuclei involved in the decay significantly reduces this computational cost, facilitating a study on how the uncertainties in the nuclear forces and transition operator propagate to the NME. The systematic construction of these ingredients in chiral effective field theory and Bayesian uncertainty quantification techniques allow us to access the theoretical uncertainty associated with \textit{ab-initio} calculations of the NME. [Preview Abstract] |
Saturday, April 17, 2021 2:54PM - 3:06PM Live |
D13.00008: Latest Results from the MAJORANA DEMONSTRATOR Neutrinoless Double-Beta Decay Search Experiment Inwook Kim The \textsc{Majorana Demonstrator} is searching for neutrinoless double-beta decay of $^{76}$Ge in an arrays of p-type, point-contact germanium detectors. It is comprised of 44 kg (30 kg enriched in $^{76}$Ge) germanium detectors. With its unprecedented energy resolution of 2.5 keV FWHM and the low background rate of 12 cts/(FWHM t yr) at the $^{76}$Ge Q-value of 2039 keV, the \textsc{Demonstrator} probes the neutrinoless double-beta decay, searching for new physics beyond the standard model. The \textsc{Demonstrator} has been operating since 2015 at the 4850' level of the Sanford Underground Research Facility. Our published results used 26 kg-yr exposure setting a half-life lower limit of 2.7$\times$10$^{25}$ yr (90\% C.L). The amount of collected exposure has doubled since the last release. In this talk, we present the status of the The \textsc{Majorana Demonstrator} and its latest results. [Preview Abstract] |
Saturday, April 17, 2021 3:06PM - 3:18PM Live |
D13.00009: Barium Tagging for NEXT Search for Neutrinoless Double Beta Decay Karen Navarro The reduction of background events is a necessity in the search for neutrinoless double beta decay \textit{(0}$\nu \beta \beta )$. One technique that could reduce backgrounds at the energy of the neutrino-less decay is the identification of the barium daughter of the double beta decay of 136Xe, known as "barium tagging". Recent results have demonstrated single Ba2$+$ ion resolution in dry state single molecule fluorescence imaging (SMFI) using custom designed fluorescent molecules. I will discuss the most recent developments in dry stage SMFI as well as presenting the R{\&}D program to be undertaken in the next few years. Particular focus will be given to the GodXilla program at UTA that uses controllable beams of Ba2$+$ ions to test SMFI sensors in the gas phase. Future R{\&}D within the NEXT collaboration will concern the transportation of Ba2$+$ ions to fluorescent sensors within large volumes of high-pressure xenon gas. Ultimately this research will result in a design for a background free 136Xe double beta decay experiment combining a high-pressure gas TPC with SMFI microscopy. [Preview Abstract] |
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