Bulletin of the American Physical Society
APS April Meeting 2019
Volume 64, Number 3
Saturday–Tuesday, April 13–16, 2019; Denver, Colorado
Session D10: Tonne Scale Neutrinoless Double Beta Decay R&D IFocus
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Sponsoring Units: DNP DPF Chair: Alfredo Galindo-Uribarri, Oak Ridge National Laboratory Room: Sheraton Governor's Square 12 |
Saturday, April 13, 2019 3:30PM - 4:06PM |
D10.00001: Towards tonne-scale Neutrinoless Double Beta Decay Experiments Invited Speaker: Andrea Pocar The search for neutrino-less double beta decay (DBD), a nuclear disintegration allowed only if neutrinos are massive Majorana particles, is entering a new phase. This decay, which has so-far eluded detection, explicitly violates total lepton number conservation by two units, offers a mechanism for the creation of matter over anti-matter, and provides a portal to unraveling the nature of neutrino mass. A new generation of experiments is being designed to push the detection sensitivity of neutrino-less DBD well beyond what currently available. These novel detectors use one or more tonnes of DBD-decaying isotope to reach half-life sensitivities on the order of 10^28 years, two orders of magnitude better thancurrent experiments. They combine well-established detector technologies, incremental design improvements, and innovations detector solutions to identify, measure, and suppress radioactive backgrounds with unprecedented efficiency thus fully exploiting the large capital and time investment of these large apparata. This talk gives an overview of current DBD searches, illustrates the science reach and status of ongoing R&D for tonne-scale experiments and sets the stage for contributed talks presented at the workshop. |
Saturday, April 13, 2019 4:06PM - 4:18PM |
D10.00002: Recent Results and Status of the Majorana Demonstrator Experiment JOSE MARIANO LOPEZ Observing neutrino less double beta decay (NLDBD) requires ultra-low background experiments with great energy resolution to distinguish against the intrinsic two neutrino double beta decay. The use of high purity germanium detectors (HPGe) is one of the best possible choices to perform this measurement due to their excellent energy resolution and background rejection capabilities. The Majorana Demonstrator, located at the Sanford Underground Research Facility, is demonstrating that a ton-scale germanium experiment is capable of probing NLDBD at the inverted ordering mass scale. The experiment uses two modular arrays of HPGe detectors, 44 kg total in mass, of which 30 kg is enriched to 88% in 76Ge. The detectors are surrounded by active and passive shielding with its most sensitives parts constructed from ultrapure materials to reduce the background. I will discuss the recent results obtained by the Majorana Demonstrator, including both the low background present in the detector and the unprecedented energy resolution achieved. |
Saturday, April 13, 2019 4:18PM - 4:30PM |
D10.00003: Recent results from NEXT-White, a demonstrator for the NEXT neutrinoless double beta decay experiment Jonathan Haefner The NEXT (Neutrino Experiment with a Xenon TPC) experiment will search for neutrinoless double beta (0νββ) decay from 136Xe using a high pressure xenon gas time projection chamber. This detector technology has several key advantages, including excellent energy resolution and powerful event classification based on track topology. The current stage of the experiment, the NEXT-White detector, has been acquiring data at Canfranc Underground Laboratory (LSC) in Spain to demonstrate the NEXT capabilities. After reviewing the experiment, we describe the process of calibration using 83mKr, demonstrating the effectiveness of correcting for spatial and temporal variations in the detector, and progress towards sub-1% energy resolution at the 136Xe double-beta decay Q-value. We also present recent results on background contamination and energy resolution. |
Saturday, April 13, 2019 4:30PM - 4:42PM |
D10.00004: Science Overview for the nEXO Experiment Lisa J. Kaufman Large ultra-low background liquid xenon (LXe) detectors have recently emerged as a promising technology that can push the neutrinoless double beta decay search to unprecedented sensitivity. An observation of this decay would demonstrate lepton number violation and the Majorana nature of the neutrino. nEXO is a proposed experiment to use a 5 tonne liquid xenon time projection chamber (TPC) enriched with the isotope 136Xe for the neutrinoless double beta decay search. The nEXO detector design and science goals to reach sufficient sensitivity to entirely cover the inverted neutrino mass ordering region, i.e. T1/2 ~1028 years, will be discussed. |
Saturday, April 13, 2019 4:42PM - 4:54PM |
D10.00005: LEGEND: The Large Enriched Germanium Experiment for Neutrinoless Double-Beta Decay Steven R Elliott The lepton number violating process of neutrinoless double-beta decay might result from the physics beyond the Standard Model. The current generation of Ge-76 experiments, the \textsc{Majorana Demonstrator} and GERDA, lead the field in both the energy resolution and ultra-low background achieved. The next generation of experiments require increased mass and further reduction of backgrounds to maximize discovery potential. Building on the successes of the \textsc{Majorana} and GERDA, the LEGEND collaboration formed to pursue a tonne-scale Ge experiment, with discovery potential at a half-life beyond $10^{28}$ years. The collaboration aims to develop a phased neutrinoless double-beta decay experimental program, starting with a 200 kg of Ge detectors fabricated from enriched Ge using the existing GERDA infrastructure at LNGS. We describe the plans and physics reach of LEGEND |
Saturday, April 13, 2019 4:54PM - 5:06PM |
D10.00006: Search for double beta decay processes in XENON1T Tianyu Zhu XENON1T was built to detect interactions from dark matter particles and has placed the most stringent limits on the coherent elastic scattering cross-section of weakly interacting massive particles on nucleon. With one of the lowest electronic recoil background from keV to MeV scale, XENON1T data provides a unique opportunity to explore neutrino physics, particularly the search for double beta decay processes. In this talk, I will describe the search for two neutrino double electron capture of 124Xe and neutrinoless double beta decay of 136Xe in XENON1T data. |
Saturday, April 13, 2019 5:06PM - 5:18PM |
D10.00007: First limit on neutrinoless quadruple beta decay of 150Nd to the 0+1 state of 150Gd Mary F Kidd, Werner Tornow If the neutrino is a Dirac particle, then observation of lepton number violation via detection of neutrinoless double beta decay is not viable. One potential lepton-number violating process that occurs even if the neutrino is a Dirac particle is neutrinoless quadruple beta (0ν4β) decay. However, the number of nuclei that can undergo 0ν4β-decay is limited; one of these nuclei is 150Nd. In 2017, NEMO-3 reported the first search for 0ν4β-decay of 150Nd to the ground state [1]. Here, we report the first half-life limit of the 0ν4β-decay to the excited 0+1 state of 150Gd. We searched for 0ν4β-decay events to excited final states of 150Gd by detecting the de-excitation gamma rays of the daughter nucleus in coincidence. The enriched Nd2O3 sample consisted of 40.33 ± 0.02 g 150Nd and was observed for 642.8 days at the Kimballton Underground Research Facility. A half-life limit for the decay to the 0+1 state of 150Gd was found to be T1/2 > 1.76 × 1020 years (90% CL). Though the predicted half life of this decay is many orders of magnitude larger, constraining this value experimentally is vital to check for potential enhancements to the decay rate. [1] https://arxiv.org/abs/1705.08847 |
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