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 X12: Double Beta Decay IIILive
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Sponsoring Units: DNP Chair: Vincenzo Cirigliano, LANL |
Tuesday, April 20, 2021 10:45AM - 10:57AM Live |
X12.00001: Cosmogenic background suppression in ICARUS using a Time-of-Flight Method Biswaranjan Behera The ICARUS detector will operate at shallow depth and therefore it will be exposed to the full surface flux of cosmic rays. This poses a problematic background to the electron neutrino appearance analysis. A direct way to suppress this background is to surround the cryostat with a detector capable of tagging incident cosmic muons with high efficiency (~95\%). A cosmic ray tagger (CRT) has been produced based on extruded organic scintillator, wavelength-shifting fibers, and silicon photomultipliers and multi-anode photomultiplier tubes. The system is about 70% installed. A full detector simulation of the CRT system has been implemented, and a large cosmogenic sample, generated via CORSIKA, has been produced. In this talk, I will present the time-of-flight method for cosmogenic background suppression in ICARUS and their application to first data from the partially commissioned CRT system. [Preview Abstract] |
Tuesday, April 20, 2021 10:57AM - 11:09AM Live |
X12.00002: Energy Calibration and Determination for the MAJORANA DEMONSTRATOR Experiment Tupendra Oli The MAJORANA DEMONSTRATOR experiment is searching for neutrinoless double-beta decay ($0\nu\beta\beta$) in $^{76}$Ge. Currently operating at the 4850$^{'}$ level of the Sanford Underground Research Facility in Lead SD, the DEMONSTRATOR consists of two modular arrays with 44 kg of p-type point contact (PPC) high purity Germanium (HPGe) detectors, of which 30 kg is enriched to 88$\%$ in $^{76}$Ge. After a recent hardware upgrade and detector swap, the array now includes four (6.7 kg) of the larger inverted-coaxial point-contact (ICPC) detectors planned for the next-generation LEGEND experiment. The MAJORANA DEMONSTRATOR has achieved the best energy resolution of any current generation $0\nu\beta\beta$ experiment, which is 2.5 keV FWHM at the 2039 keV Q-value. Such an excellent energy resolution plays a key role in rare event searches and it is achieved through regular $^{228}$Th calibrations and well-developed energy determination methods. In this talk, I will discuss the DEMONSTRATOR$^{'}$s energy calibration process, with a focus on the energy determination methods. [Preview Abstract] |
Tuesday, April 20, 2021 11:09AM - 11:21AM Not Participating |
X12.00003: Internal Scanner for Rapid Characterization of $^{76}$Ge detectors used in LEGEND-200 Aaron Engelhardt The LEGEND collaboration is developing an experimental search for neutrinoless double beta decay ($0\nu\beta\beta$) in the $^{76}$Ge isotope with a discovery potential of a half-life beyond $10^{28}$ years. The first phase, Legend-200, is an experimental search using 200 kg of $^{76}$Ge-enriched germanium, with data taking beginning in 2021. The search for $0\nu\beta\beta$ requires a precise understanding of the behaviour of germanium detectors, necessitating extensive detector characterization. As characterization for Legend-200 is underway, there is an effort at UNC to develop a scanner for the characterization of the $\alpha, \beta,$ and $\gamma$ response on and near the passivated surface of inverted coaxial point-contact detectors (ICPC) to be deployed in the experiment. Scanning a selected sample of points in a low background environment allows for rapid characterization. An $^{241}$Am source provides 5.45 MeV $\alpha$s for measuring the $\alpha$ response on the passivated surface while a $^{137}$Cs source provides 625 keV internal conversion electrons for studying the $\beta$ response. The development and initial results of the internal scanner will be presented. [Preview Abstract] |
Tuesday, April 20, 2021 11:21AM - 11:33AM Live |
X12.00004: Low Energy Background Modeling for LEGEND-1000 Jackson Waters The LEGEND-1000 experiment will search for neutrinoless double beta decay (0$\nu\beta\beta$) in $^{76}$Ge with 1000 kg total of high-purity Germanium (HPGe) detectors and a background goal of $<$ 0.03 cts / (FWHM-t-yr). It will utilize technologies from the current {\sc Majorana} and GERDA experiments, along with those from its upcoming first phase LEGEND-200, to achieve a discovery potential at a half-life exceeding $10^{28}$ years. Due to the low background, keV-level energy thresholds, and improved detector technology, a low energy, beyond the Standard Model (BSM) physics program is possible in parallel with 0$\nu\beta\beta$ studies. In order to look for BSM physics at low energies, a systematic study of all backgrounds below 100 keV has to be performed. This talk will discuss the various backgrounds considered, and results from Monte Carlo simulations will be shown. [Preview Abstract] |
Tuesday, April 20, 2021 11:33AM - 11:45AM Live |
X12.00005: The Interpretable Machine Learning Analysis for MAJORANA Demonstrator Aobo Li Neutrinoless Double Beta Decay(0$\nu \beta \beta )$ is one of the major research interests in neutrino physics. The discovery of 0$\nu \beta \beta $ would answer persistent puzzles in the standard model. In the search of 0$\nu \beta \beta $, The Majorana Demonstrator experiment retains the best energy resolution and one of the lowest backgrounds at the region of interest. Data is collected from 44kg of enriched and natural Germanium-76 crystals operating as a p-type point-contact detector array. Several pulse shape parameters have been developed to reject backgrounds. To collectively analyze those pulse shape parameters, we developed a fully interpretable boosted decision tree (BDT) model that has the potential to outperform the traditional selection criteria. By interpreting the BDT, we find that it uses parameter correlation to identify known background event categories that have required supplementary cuts in the traditional analysis. We demonstrated that the BDT analysis and traditional analysis benefit each other in a reciprocal way. [Preview Abstract] |
Tuesday, April 20, 2021 11:45AM - 11:57AM Live |
X12.00006: First Results from the CAGE Scanner: Investigating Surface Backgrounds in HPGe Detectors for LEGEND Gulden Othman A potential source of backgrounds in a ton-scale $^{76}$Ge-based neutrinoless double-beta decay experiment could arise from ionizing particle interactions occurring near the surfaces of high purity germanium (HPGe) detectors. The Collimated Alphas, Gammas, and Electrons scanner (CAGE) is a test stand that allows for in-depth studies of surface events on HPGe detectors. This is accomplished by using vacuum-side, moveable and rotatable collimated radiation sources to characterize the response of HPGe detectors to radiation at specific locations and incidence angles on the detector surface. LEGEND is a search for neutrinoless double-beta decay in the $^{76}$Ge isotope that will begin operation of a 200 kg array, LEGEND-200, in 2021, with a plan to scale up to 1000 kg of $^{76}$Ge-enriched HPGe detectors, LEGEND-1000, in a phased approach. To reach LEGEND-1000's goal of a discovery sensitivity at half-life beyond 10$^{28}$ yr, understanding and discriminating against backgrounds from surface events is essential. In this talk we present the first results from CAGE with studies using an alpha source, and discuss the future prospects of CAGE. [Preview Abstract] |
Tuesday, April 20, 2021 11:57AM - 12:09PM Live |
X12.00007: Coupled-cluster calculations of neutrinoless double-beta decay in $^{48}$Ca Samuel Novario, Peter Gysbers, Jon Engel, Gaute Hagen, Gustav Jansen, Titus Morris, Petr Navrátil, Thomas Papenbrock, Sofia Quaglioni We use coupled-cluster theory and nuclear interactions from chiral effective field theory to compute the nuclear matrix element for the neutrinoless double-beta decay of $^{48}$Ca. Benchmarks with the no-core shell model in several light nuclei and in the traditional shell model in the $pf$ shell inform us about the accuracy of our approach. For $^{48}$Ca we find a relatively small matrix element. We also compute the nuclear matrix element for the two-neutrino double-beta decay of $^{48}$Ca and find agreement with data when using a quenching factor deduced from two-body currents in the recent ab-initio calculation of the Ikeda sum-rule in $^{48}$Ca [Gysbers {\it et al.}, Nature Physics {\bf 15}, 428-431 (2019)]. Work available as [S. J. Novario, P. Gysbers, J. Engel, G. Hagen, G. R. Jansen, T. D. Morris, P. Navrátil, T. Papenbrock, S. Quaglioni, arXiv:2008.09696]. [Preview Abstract] |
Tuesday, April 20, 2021 12:09PM - 12:21PM Live |
X12.00008: DUNE-Beta: Prospects for a 100-ton scale neutrino-less double-beta decay at DUNE. Fernanda Psihas The DUNE physics program primarily focuses on signals in the GeV energy range. In recent years, DUNE's potential as a low-energy experiment has been fruitfully explored, specifically regarding its sensitivity to signals as low as 5-10 MeV such as those associated with supernova burst and solar neutrinos. In this presentation I discuss the requirements and modifications that could extend DUNE's sensitivity to energies as low as 2MeV and would enable us to further expand DUNE's physics program to searches for neutrino-less double-beta decay in xenon-doped liquid argon at the multi-ton scale. I will present the modifications we propose with corresponding sensitivity estimates for $m_/beta/beta$ measurements beyond the inverted hierarchy region, and describe the rich and diverse R&D program that this research avenue would open for DUNE. [Preview Abstract] |
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