Bulletin of the American Physical Society
APS April Meeting 2023
Volume 68, Number 6
Minneapolis, Minnesota (Apr 15-18)
Virtual (Apr 24-26); Time Zone: Central Time
Session G11: Neutrinos I |
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Sponsoring Units: DPF Chair: Andre de Gouvea, Northwestern University Room: Marquette II - 2nd Floor |
Sunday, April 16, 2023 10:45AM - 10:57AM |
G11.00001: PROSPECT-I Measurement of Absolute Reactor Antineutrino Flux Andrew Meyer1 on behalf of the PROSPECT Collaboration 1 Department of Physics and Astronomy, University of Hawaii, Honolulu, HI, USAandrewm9@hawaii.edu Andrew Meyer The Precision Reactor Oscillation and SPECTrum (PROSPECT) experiment is a short-baseline reactor experiment designed to measure the spectrum of antineutrinos and search for evidence of short baseline sterile neutrino oscillations. From 2018 to 2019, the first-generation detector, PROSPECT-I, took data while located roughly 7 m from the High Flux Isotope Reactor (HFIR), an 85 MW, compact core, highly enriched research reactor at Oak Ridge National Laboratory (ORNL). PROSPECT-I was a segmented 6Li-loaded liquid scintillator detector which detected neutrinos via inverse beta decay (IBD) events, by detecting the scintillation light of the IBD positron and other particles produced when the IBD neutron captured on the 6Li. PROSPECT-I has demonstrated the highest signal-to-background ratio of any surface antineutrino detector with minimal overburden, placing stringent limits on eV scale sterile neutrino oscillations, setting new direct limits on boosted dark matter models, and providing one of the most precise measurements to date of the 235U antineutrino spectrum. This talk will present ongoing work by the PROSPECT collaboration towards making an absolute flux measurement of the reactor antineutrinos, and detail ongoing work on measuring the detector’s neutron detection efficiency. A significant focus of this work is calculating inefficiencies caused by the fraction of neutrons capturing on targets other than 6Li. |
Sunday, April 16, 2023 10:57AM - 11:09AM |
G11.00002: Final U235 Antineutrino Spectrum Analysis by PROSPECT-I Christian Roca Catala The Precision Reactor Oscillation and SPECTrum (PROSPECT) experiment measures the spectrum of antineutrinos from the High Flux Isotope Reactor (HFIR) and searches for potential short-baseline oscillations. The most recent publication by PROSPECT presents a refined analysis that improves upon previous results by including Single Ended Event Reconstruction (SEER) of the previously unused segments, and the careful data splitting (DS) of the different time periods to maximize the available statistics. |
Sunday, April 16, 2023 11:09AM - 11:21AM |
G11.00003: The PROSPECT-II physics goals Ohana Benevides Rodrigues, Bryce R Littlejohn The Precision Reactor Oscillation and SPECTrum (PROSPECT) experiment consists of a segmented liquid scintillator antineutrino detector located 7m from the highly-enriched High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory that aims to explore short-baseline antineutrino oscillations. Its first phase of data collection, called PROSPECT-I, ran from 2018 to 2019 and resulted in several high- precision analyses, including multiple 235U antineutrino spectrum measurements and eV-scale sterile antineutrino oscillation searches. |
Sunday, April 16, 2023 11:21AM - 11:33AM |
G11.00004: PROSPECT-II Design and R&D Bryce R Littlejohn The Precision Reactor Oscillation and SPECTrum (PROSPECT) experiment is a short-baseline reactor experiment with the goal of measuring the antineutrino spectrum from the High Flux Isotope Reactor (HFIR). It searches for potential short-baseline oscillations and the existence of sterile neutrinos. PROSPECT has already set new limits on the existence of eV-scale sterile neturinos while achieving the highest signal-to-background ratio on any surface antineutrino detector. The collaboration has developed an upgraded detector design, called PROSPECT-II, which will increase the detector's statistics and physics sensitivity. This talk will describe major design features of the PROSPECT-II detector, highlighting improved design elements with respect to the first-generation PROSPECT-I detector, as well as recent R&D accomplishments. |
Sunday, April 16, 2023 11:33AM - 11:45AM |
G11.00005: The PROSPECT-II detector calibration system Xiaobin Lu PROSPECT is a ton-scale reactor-based antineutrino experiment, operated at very short baselines from the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. The PROSPECT experiment has reported strong limits on eV-scale sterile neutrinos, made a precision measurement of the reactor antineutrino spectrum from U-235, and demonstrated the observation of reactor antineutrinos in an aboveground detector with good energy resolution and well-controlled backgrounds. An upgraded detector, PROSPECT-II, will leverage existing expertise and investment and will resolve previous technical issues to ensure long term stability. The new design necessitates some changes to the calibration strategy. For example, the separation of photomultiplier tubes (PMTs) from liquid scintillator (LS) volume requires an alternative energy scale calibration method and careful consideration of introduced inter-segment cross-talk. This talk will describe calibration strategy for PROSPECT-II. |
Sunday, April 16, 2023 11:45AM - 11:57AM |
G11.00006: An Improved Search for Two-neutrino Double-Beta Decay of 136Xe to the 01+ excited state of 136Ba with the Complete EXO-200 Dataset Yasheng Fu The EXO-200 detector was a single phase liquid xenon time projection chamber located at the Waste Isolation Pilot Plant to search for neutrinoless double beta decay (0νββ) of 136Xe. EXO-200 stopped operation in Dec 2018 after successful Phase-I and II operation. The complete dataset offers valuable opportunities for many interesting physics searches in addition to 0νββ. Here we will present a search for the 2νββ decay of 136Xe to the 01+ excited state of 136Ba. Once discovered, it could help improve the understanding of nuclear matrix elements, potentially contributing to the determination of the effective Majorana neutrino mass from 0νββ half-life measurements. The previous search published by EXO-200 in 2016 based on 100 kg·yr exposure of 136Xe in Phase-I obtained a half-life limit of 6.9×1023 yr at 90% CL. With doubled exposure including Phase-II data, new machine learning based background discrimination approaches, and greatly increased detection efficiency due to optimized event selection criteria, an improved search utilizing the complete EXO-200 dataset is performed. In this talk, we present the analysis methods and results of searching for the 2νββ decay of 136Xe to the 01+ excited state of 136Ba with the complete EXO-200 dataset. |
Sunday, April 16, 2023 11:57AM - 12:09PM |
G11.00007: Using supernova neutrinos to probe the strange quark contribution to the proton spin Bhavesh Chauhan The strange quark contribution to proton's spin (Δs) is a fundamental quantity that is poorly determined from current experiments. Neutrino-proton elastic scattering (pES) is a promising channel to measure this quantity, and requires an intense source of low-energy neutrinos and a low-threshold detector with excellent resolution. In this paper, we propose that neutrinos from a galactic supernova and their interactions with protons in large-volume scintillation detectors can be utilized to determine Δs. The spectra of all flavors of supernova neutrinos can be independently determined using a combination of DUNE and Super-(Hyper-)Kamiokande. This allows us to predict pES event rates in JUNO and THEIA, and estimate Δs by comparing with detected events. We find that the projected sensitivity for a supernova at 1 kpc (10 kpc), is approximately ± 0.01(± 0.15). We also consider the possibility of measuring Δs using neutronization burst, which is a robust prediction of supernova simulations. Interestingly, the limits from a nearby supernova would be comparable to the results from lattice QCD, and better than polarized deep-inelastic scattering experiments. Using supernova neutrinos provides a true Q2 → 0 measurement, and thus an axial-mass independent determination of Δs. |
Sunday, April 16, 2023 12:09PM - 12:21PM |
G11.00008: Heavy Water Cherenkov Detector Energy Scale Calibration via Michel Electron Detection Eli M Ward At Oak Ridge National Laboratory (ORNL), the COHERENT collaboration has been building a heavy water Cherenkov detector to measure the neutrino flux coming from the Spallation Neutron Source (SNS). This detector is a steel cylinder filled with light water with an inner acrylic vessel holding heavy water and twelve PMTs lining the inside of the top lid. It began accumulating statistics in summer 2022 with light water only, since the inner acrylic tank and heavy water were not installed until early 2023. In this initial run with only light water, we identified Michel electrons produced from the decay of stopped cosmic muons within the detector and used these measurements to calibrate the energy scale of the detector. This presentation will describe this energy scale calibration process in the initial light water only phase of the Cherenkov detector. |
Sunday, April 16, 2023 12:21PM - 12:33PM |
G11.00009: Studies of Neutrino Interactions and Dark Matter with the COHERENT experiment Rex Tayloe The COHERENT collaboration operates an array of detectors at the ORNL Spallation Neutron Source (SNS) to measure coherent elastic neutrino nucleus scattering (CEvNS) and to search for dark matter. The 1.4 MW SNS pulsed proton beam produces an intense neutrino flux and may be producing dark matter particles. Our low-energy-threshould detectors sited in the low-background "Neutrino Alley" near this source are producing world-leading sensitivity for these measurements. We observed the first events from CEvNS in 2017 with a cesium-iodide scintillation detector and have new results from an expanded data set. We followed up with a measurement, published in 2020 on a lighter argon nucleus confirming the CEvNS hypothesis. These data sets can also be used to search for dark matter as predicted in a class of portal-particle dark matter theories and our recent cesium-iodide results elimate some parameter-space required to explain cosmologically observed dark-matter. These measurements will be presented along with plans for further extending our physics reach with new detectors in the near future. |
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