Bulletin of the American Physical Society
APS April Meeting 2022
Volume 67, Number 6
Saturday–Tuesday, April 9–12, 2022; New York
Session L04: New Results From Neutrino DetectorsInvited Live Streamed Undergrad Friendly
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Sponsoring Units: DNP Chair: Gabriel Orebi Gann, LBL Room: Salon 2 |
Sunday, April 10, 2022 3:45PM - 4:21PM |
L04.00001: The Gallium Anomaly and the Question of Sterile Neutrinos Invited Speaker: Steve R Elliott The Baksan Experiment on Sterile Transitions (BEST) was designed to investigate the deficit of electron neutrinos, νe, observed in previous gallium-based radiochemical measurements with high-intensity neutrino sources, commonly referred to as the gallium anomaly, which could be interpreted as evidence for oscillations between νe and sterile neutrino (νs) states. A 3.414-MCi 51Cr νe source was placed at the center of two nested Ga volumes and measurements were made of the production of 71Ge through the charged current reaction,71Ga(νe,e)71Ge, at two average distances. The measured production rates for the inner and the outer targets respectively are $54.9+2.5-2.4(stat)±1.4 (syst) and 55.6+2.7-2.6 (stat)±1.4 (syst) atoms of 71Ge/d. The ratio (R) of the measured rate of 71Ge production at each distance to the expected rate from the known cross section and experimental efficiencies are Rin=0.79±0.05 and Rout= 0.77±0.05. The ratio of the outer to the inner result is 0.97±0.07, which is consistent with unity within uncertainty. The rates at each distance were found to be similar, but 20-24% lower than expected, thus reaffirming the anomaly. These results are consistent with νe toνs oscillations with a relatively large Δm2 (>0.5 eV2) and mixing sin2 2θ (about 0.4). |
Sunday, April 10, 2022 4:21PM - 4:57PM |
L04.00002: Neutrino Physics with Large Liquid Scintillator Detectors Invited Speaker: Logan Lebanowski Scintillator detectors will continue to make critical measurements and discoveries with neutrinos, from their first observation to their use as tools to study the Earth, the Sun, supernovae, and more. These detectors continue to increase in size, extending their physics reach and deepening their impact. Currently-operating 780-ton SNO+ has measured neutrinos from the Sun and distant nuclear reactors, both of which are reported here. And in the near future, SNO+ will begin its search for the neutrinoless double beta decay of 130Te. Forthcoming 20-kton JUNO would make the most precise measurements of several neutrino oscillation parameters, and attain leading sensitivities in studies of neutrinos from various sources. Results and prospects of these and other experiments are overviewed, as well as ongoing R&D, which is exploring various approaches to improving the properties and deployment of scintillator detector elements, including the distinction of scintillation and Cherenkov photons. |
Sunday, April 10, 2022 4:57PM - 5:33PM |
L04.00003: New Results from the MAJORANA DEMONSTRATOR Invited Speaker: Wenqin Xu A discovery of neutrinoless double beta decay (0νββ) would establish that neutrinos are their own antiparticles, prove total lepton number violation, and provide a mechanism for generating non-zero neutrino masses. The MAJORANA DEMONSTRATOR experiment searches for 0νββ in 76Ge with two shielded modules of high purity germanium (HPGe) detectors, ~30 kg of which are enriched to 88% in 76Ge. The enriched detectors of the DEMONSTRATOR took data between 2015 and 2021, when they were removed for deployment in the Large Enriched Germanium Experiment for Neutrinoless ββ Decay (LEGEND). An upgrade of a module in 2020 with improved connectors and cabling successfully made all of its detectors operational, and it allowed the deployment of four inverted coaxial point contact (ICPC) enriched 76Ge detectors to study their performance prior to use in LEGEND. Excellent energy performance has been achieved with the DEMONSTRATOR HPGe detectors, including low energy threshold, great linearity, and a FWHM energy resolution that is approaching 0.1% at the double beta decay Q-value, the best in all 0νββ experiments. Not only has the DEMONSTRATOR successfully demonstrated the feasibility and advantages of the ton-scale LEGEND project, but it also has been highly productive and competitive in a broad range of physics topics. In this talk, we will present new results from the DEMONSTRATOR’s rich physics program on 0νββ decay, solar axions, bosonic dark matter, quantum wavefunction collapse, and more physics beyond the Standard Model. In addition, we will discuss progress towards background modeling along with new results from studies of cosmogenic and neutron backgrounds, which help inform the design of next-generation experiments. |
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