Bulletin of the American Physical Society
Fall 2022 Meeting of the APS Division of Nuclear Physics
Volume 67, Number 17
Thursday–Sunday, October 27–30, 2022; Time Zone: Central Daylight Time, USA; New Orleans, Louisiana
Session LD: Mini-Symposium: The Physics of Double Beta Decay - Machine Learning Tools; Neutrinos I; Neutrino Mass I |
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Chair: Pranava Teja Surukuchi, Yale University Room: Hyatt Regency Hotel Celestin B |
Saturday, October 29, 2022 2:00PM - 2:12PM |
LD.00001: The Machine Learning Overview of Majorana Demonstrator Aobo Li, Wenqin Xu Neutrinoless Double Beta Decay (0νββ) is one of the major research interests in neutrino physics. The discovery of 0νββ would answer persistent puzzles in the standard model. In the search for 0νββ, the Majorana Demonstrator experiment retains the best energy resolution and one of the lowest backgrounds in the region of interest. Data is collected from enriched and natural Germanium-76 crystals operating as detector arrays of p-type point-contact and inverted-coaxial point-contact detectors, with a total 64.5 kg-yr final active enriched exposure. We have developed a suite of machine learning tools to collectively analyze the pulse shape parameters used to reject backgrounds. In this talk, we will discuss two machine learning approaches to analyze Majorana data: an interpretable BDT analysis to analyze pulse shape discrimination parameters and a recurrent neural network analysis to analyze the waveform directly. These analyses have the potential to further improve background rejection and reciprocally benefit the traditional analysis. |
Saturday, October 29, 2022 2:12PM - 2:24PM |
LD.00002: Event Reconstruction in the SNO+ Experiment Tereza Kroupova SNO+ is a kilo-tonne scale neutrino detector with the primary goal of searching for neutrinoless double beta decay in tellurium-130. The inner vessel is currently of the SNO+ detector is currently filled with organic liquid scintillator, which will be doped with the double beta isotope. While liquid scintillator detectors are ideal tools for neutrinoless double beta decay searches due to their exceptional mass scalability, good signal efficiency and low cost, their capability of reliable particle identification for active backround rejection is often questioned. This talk will focus on new event reconstruction and particle identification techniques, their performance, and their use in SNO+ for enhancing the sensitivty to neutrinoless double beta decay as well as other physics searches. |
Saturday, October 29, 2022 2:24PM - 2:36PM |
LD.00003: Machine Learning Denoising of nEXO's Time Project Chamber using an Unsupervised Variational Autoencoder Jason P Brodsky The nEXO experiment will use a single-phase liquid xenon time projection chamber (TPC) to search for neutrinoless double beta decays of 136Xe. As a single-phase TPC, nEXO will observe drift electrons using sensing electrodes, reducing complexity but increasing electronics noise relative to the two-phase approach. While nEXO is robust against this noise at the 2.5 MeV signal energy of interest and its multi-variate signal/background separation, advanced mitigations of this noise will enhance nEXO’s scientific reach by improving its energy resolution and topological background discrimination. |
Saturday, October 29, 2022 2:36PM - 2:48PM |
LD.00004: KATRIN: Status Update Alexander Marsteller The KArlsruhe TRItium Neutrino (KATRIN) experiment has produced the first sub-eV sensitivity direct neutrino-mass scale measurement from tritium beta decay, and aims to improve its sensitivity to 0.2 eV (90% C.L.). In order to reach this sensitivity, a large number of events near the kinematic endpoint of the tritium beta decay need to be recorded to reduce the statistical uncertainty. Systematic effects affecting the measurement also need to be accurately known and well understood. In this presentation we will report on progress towards the next neutrino-mass result with regards to statistical and systematic uncertainties. |
Saturday, October 29, 2022 2:48PM - 3:00PM |
LD.00005: First neutrino mass limit with CRES: A Bayesian analysis for Project 8 Phase II Talia E Weiss Project 8 aims to determine the absolute neutrino mass scale from the shape of the tritium beta decay spectrum near its endpoint. For this purpose, the collaboration developed a novel frequency-based technique for measuring electron energies: Cyclotron Radiation Emission Spectroscopy (CRES). This talk presents the Bayesian analysis of the first tritium spectrum obtained with CRES, which contains 3770 events and no background events above the endpoint. We develop an analytic likelihood model of the beta spectrum and detector response, suitable for Bayesian inference with the Stan computing platform. Systematic uncertainties are propagated by incorporating them into prior distributions. Monte Carlo (MC) studies validate the likelihood model, with MC inputs sampled from priors. Separate MC studies demonstrate that priors chosen for the endpoint and neutrino mass are weakly informative. We report an endpoint result of E0=18553±17 eV (literature: 18574 eV) and an electron-weighted neutrino mass limit of mβ<169 eV/c2 (90% C.L.). A parallel frequentist analysis produced consistent results. |
Saturday, October 29, 2022 3:00PM - 3:12PM |
LD.00006: Deep Learning based CRES track and event reconstruction in Project 8 Razu Mohiuddin Project 8 is a next generation experiment aiming for a 40 meV neutrino mass sensitivity. This goal will be achieved by studying the tritium beta decay endpoint using the novel Cyclotron Radiation Emission Spectroscopy (CRES) technique. The endpoint can be resolved by magnetically trapping decay electrons and studying the spectrogram of their cyclotron radiation. These spectrograms are obtained by short-time Fourier transform of the time domain signals. In the spectrograms, signals of electron cyclotron radiation appear as tracks on top of background noise. We developed deep learning based models to find electron signals, and compared its performance to the pixel-grouping based baseline method for simulated data. This talk will discuss improvements in identifying electron tracks from noise background over the traditional baseline method. Efficiency gain and application in future phases of the experiment will also be highlighted. |
Saturday, October 29, 2022 3:12PM - 3:24PM |
LD.00007: Atom-Source Development for Project 8 Alec C Lindman The Project 8 experiment aims to make a direct measurement sensitive to much of the unexplored range of neutrino masses, including all of the inverted hierarchy. Past experiments used molecular tritium, in which final states impose a large energy smearing that limits neutrino mass reach. Project 8 will use atomic tritium to reach a design sensitivity of mβ ≤ 40 meV/c2. This requires about 1020 tritium atoms held at tens of mK in a many-cubic-meter magnetic trap, which translates to a requirement of ≳ 1019 atoms/s at the atom source. |
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