Bulletin of the American Physical Society
2020 Fall Meeting of the APS Division of Nuclear Physics
Volume 65, Number 12
Thursday–Sunday, October 29–November 1 2020; Time Zone: Central Time, USA
Session MM: Mini-Symposium: Neutrinos III |
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Chair: Joe Carlson, LANL |
Saturday, October 31, 2020 2:00PM - 2:36PM |
MM.00001: Recent Developments in Reactor Neutrino Physics Invited Speaker: Bryce Littlejohn Models of antineutrino production in nuclear reactors predict absolute detection rates and energy spectra at odds with the existing body of direct reactor antineutrino measurements. If these discrepancies are taken seriously, then they must be indicative of a misunderstanding of neutrino production in nuclear reactor cores and/or the fundamental properties of neutrinos. A variety of reactor neutrino experiments at short $(<20 m)$ and long $(>100m)$ reactor-detector distances have provided new insights into these two explanations for existing flux and spectrum anomalies. This talk will provide an overview of these developments while highlighting recent measurements performed by PROSPECT, which has operated a 4 ton segmented lithium-doped liquid scintillator detector covering baseline ranges of $\sim$7-11 meters from the U235-enriched High Flux Isotope Reactor at Oak Ridge National Laboratory. This experiment has demonstrated the feasibility of precision on-surface reactor antineutrino detection, advanced understanding of antineutrino production by the primary fission isotope U235, and placed world-leading limits on sterile neutrino oscillations. [Preview Abstract] |
Saturday, October 31, 2020 2:36PM - 2:48PM |
MM.00002: Project 8 neutrino mass experiment: Phase II tritium endpoint result and Phase III status Elise Novitski Project 8 is a neutrino mass experiment that uses a new technique, Cyclotron Radiation Emission Spectroscopy (CRES), to make a differential measurement of the tritium $\beta^{-}$ spectrum. Project 8 aims to use the advantages of CRES to surmount the systematic and statistical limitations of current-generation direct neutrino mass measurement methods, proceeding in a phased approach toward a goal of effective electron antineutrino mass sensitivity of ${\sim}$40 meV/c$^2$ using atomic tritium. This talk will report on the status of Project 8, from the final result of the Phase II endpoint measurement in molecular tritium to plans for the Phase III free-space CRES and atomic tritium demonstrations that will pave the way to an integrated Phase IV at the final sensitivity. [Preview Abstract] |
Saturday, October 31, 2020 2:48PM - 3:00PM |
MM.00003: Beta Decay of Molecular Tritium Diana Parno When tritium beta decay occurs within a TT or HT molecule, the resulting distribution of electronic, vibrational and rotational excitations of the final-state molecule modifies the shape of the beta spectrum. A robust understanding of this distribution is essential for experiments such as KATRIN and Project 8, which extract neutrino-mass information from the beta spectrum of TT decay. The Tritium Recoil Ion Mass Spectrometer (TRIMS), a coincidence time-of-flight mass spectrometer, has measured the probability with which the molecule dissociates following beta decay in HT and TT, a direct test of the theoretical final-state distribution. I will give an overview of the experiment, explaining design features that address known flaws in historical measurements that disagreed with the theory. Our results agree closely with theoretical expectations in both molecules. [Preview Abstract] |
Saturday, October 31, 2020 3:00PM - 3:12PM |
MM.00004: Benchmarking of neutrino energy reconstruction methods using electron-deuterium scattering data Anjali Nambrath High-precision measurements of neutrino oscillation parameters require a deep understanding of neutrino interactions with the atomic nuclei of detectors. These nuclear effects are one of the main sources of systematic uncertainty in neutrino experiments. To help resolve this, we take advantage of electron-deuteron scattering data using the large-acceptance CLAS detector at Jefferson Lab. This data could be particularly useful in this process, because such a light and simple nucleus is relatively well-understood. The elimination of tangled nuclear effects is also an attractive reason to consider deuterium-based detectors. I will present our results on the benchmarking of neutrino energy reconstruction methods using 5-GeV electron-deuteron scattering data. [Preview Abstract] |
Saturday, October 31, 2020 3:12PM - 3:24PM |
MM.00005: Tritium $\beta$-Energy Spectrum Analysis in Project 8 Phase II Yu-Hao Sun The Project 8 experiment aims to determine the absolute neutrino mass scale by searching for a distortion to the tritium $\beta$-energy spectrum near the endpoint using the Cyclotron Radiation Emission Spectroscopy (CRES) technique. The first molecular tritium $\beta$-energy spectrum using CRES has been observed in Phase II of Project 8, from which the endpoint energy has been extracted. This talk presents the data analysis of the tritium $\beta$-energy spectrum to produce the final result of the Phase II endpoint measurement, with a focus on systematic effects. [Preview Abstract] |
Saturday, October 31, 2020 3:24PM - 3:36PM |
MM.00006: Application of the Latest Nuclear Data Bases to Reactor Antineutrino Research R.J. Lorek, A. Mattera, E.A. McCutchan, A.A. Sonzogni Nuclear databases continue to play an important role in understanding the production of electron antineutrinos in nuclear reactors, which is currently of importance for refining our understanding of neutrino oscillations, reactor monitoring, and non-proliferation. In order to provide more reliable results, the ENDF/B decay data sub-library continues to be updated to include the latest available \(\beta\)-decay results from various neutron rich nuclides that utilize TAGS and high-resolution gamma spectroscopy techniques. Additionally, we have added half-lives and delayed neutron probabilities from the recent IAEA Coordinated Research Project on the subject. Here the latest version of the ENDF/B decay data sub-library is applied to calculate a summation Inverse Beta Decay antineutrino spectra as a function of prompt energy, and draw comparisons to the recently published Daya Bay results. [Preview Abstract] |
Saturday, October 31, 2020 3:36PM - 3:48PM |
MM.00007: Modeling the TRIMS Experiment Byron Daniel By analyzing the kinematics of tritium beta decay, one can directly measure the neutrino-mass scale. Since modern tritium-based experiments use a molecular source and molecular excitations modify the beta spectrum, one must also understand these ``final-state'' excitations precisely in order to properly analyze the spectral shape. Historical mass spectroscopy measurements disagreed with theory. The Tritium Recoil-Ion Mass Spectrometer (TRIMS) experiment is a coincidence time-of-flight mass spectrometer designed to test the theory used in the neutrino-mass analysis. In this presentation, I will speak in detail about the Geant4 modeling of the TRIMS experiment, which explains features in the data such as secondary emission and dissociation in flight. [Preview Abstract] |
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