Bulletin of the American Physical Society
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 63, Number 12
Tuesday–Saturday, October 23–27, 2018; Waikoloa, Hawaii
Session EN: Neutrino Physics II |
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Chair: Javier Menendez, University of Tokyo Room: Hilton Kohala 4 |
Thursday, October 25, 2018 7:00PM - 7:15PM |
EN.00001: Overview of the Large Enriched Germanium Experiment for Neutrinoless Double Beta Decay (LEGEND) Keith Rielage The observation of neutrinoless double-beta decay (0νββ) would show that lepton number is violated and reveal that neutrinos are Majorana particles. Further, a discovery-capable experiment covering the inverted ordering region, with effective Majorana neutrino masses of 15 - 50 meV (depending on the specific model), requires an experiment utilizing about a ton of isotope with excellent energy resolution and extremely low backgrounds, at the level of ∼0.1 count /(FWHM⋅t⋅yr) in the region of the signal. The current generation experiments GERDA and the MAJORANA DEMONSTRATOR that use high purity germanium detectors enriched in 76Ge with an intrinsic energy resolution of 0.12%, have achieved the lowest backgrounds in the 0νββ signal region of all 0νββ experiments. Building on this success, the LEGEND collaboration has been formed to pursue a ton-scale 76Ge experiment. The collaboration aims to develop a phased 0νββ experimental program with discovery potential at a half-life approaching or at 1028 years. This talk will provide an overview of the phased approach for LEGEND and a discussion of the current status and design. |
Thursday, October 25, 2018 7:15PM - 7:30PM |
EN.00002: Fabrication and Characterisation of Front-End Electronics for the Large Enriched Germanium Experiment for Neutrinoless ββ Decay (LEGEND) Experiment Michael Willers A highly promising way to search for neutrinoless double beta decay is the use high-purity germanium detectors enriched in the isotope 76Ge. A discovery of this non-standard decay would prove that lepton number is not conserved and that the neutrino is its own anti-particle. The LEGEND experiment is a next-generation ton-scale 76Ge experiment aiming to probe this process with unprecedented sensitivity. A low-radioactivity signal readout has to conform to stringent radiopurity constraint and its performance directly impacts the effectiveness of background discrimination. In this contribution, the front-end electronics concept for the first 200-kg phase of the experiment (LEGEND-200) will be presented. The fabrication process and the results from the characterisation of prototype devices will also be presented. |
Thursday, October 25, 2018 7:30PM - 7:45PM |
EN.00003: The Search for Double-Beta Decay to Excited States in $^{76}$Ge using the \textsc{Majorana Demonstrator} Ian Guinn The Majorana Demonstrator is studying double-beta decay in $^{76}$Ge using a modular array of high purity Germanium detectors. The experiment is constructed using low-background materials and is currently operating at the '4850 level of the Sanford Underground Research Facility. The experiment consists of two modules with 29~detectors each, consisting of 44.8~kg of germanium detectors, 29.7~kg of which are enriched to 88\% in $^{76}$Ge. The granularity of the detector array and the p-type point contact detector geometry enable discrimination of single- and multi-site events. The \textsc{Demonstrator} is also searching for double-beta decay of $^{76}$Ge to three different excited states (E.S.s) of $^{76}$Se. The E.S. decays are inherently multi-site events with one or two $\gamma$-rays produced nearly simultaneously to the $\beta\beta$-decay. This talk will present the \textsc{Majorana Demonstrator}'s search for $\beta\beta$-decay to excited states in multi-site events. |
Thursday, October 25, 2018 7:45PM - 8:00PM |
EN.00004: Muon Capture and the Axial Structure of the Nucleon Peter Kammel, Richard J Hill, William J Marciano, Alberto Sirlin
The weak charged-current reaction of muon capture has much in common with several aspects of neutrino physics. Its basic process, μp->nν is the inverse of quasi-elastic νn scattering, while muon capture on deuterium is governed by the same physics as solar pp fusion and νd scattering at SNO. In heavier nuclei, recent muon capture experiments explore virtual intermediate states of 0ν2β candidates. The presentation will focus on muon capture in hydrogen and the axial radius of the nucleon. We [R. Hill et al., 2018, Rep. Prog. Phys. in press] used the recent model independent reevaluation of of the axial radius rA2 (z exp.) = 0.46(22) fm2 from νd scattering and the hydrogen capture rate from the MuCap experiment, to update the value of the induced pseudoscalar form factor gP and, alternatively, to determine rA2 (MuCap) = 0.46(24) fm2 from muon capture. The impact of this result and the motivation for new, 3-fold improved muon capture experiment regarding neutrino quasi-elastic neutrino scattering in the GeV region is discussed.
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Thursday, October 25, 2018 8:00PM - 8:15PM |
EN.00005: Axial form factor and neutrino-nucleus cross sections Alexander Friedland, Emilie Passemar, Kevin James Quirion, Clayton Ristow Neutrino-nucleus cross sections in the GeV energy range suffer from large uncertainties, yet good knowledge of these cross sections is essential for the success of the current and next generation of neutrino experiments, particularly DUNE, the Deep Underground Neutrino Experiment. In this talk, we study the impact of different assumptions concerning the axial form factor on the neutrino-nucleus cross-section prediction. In particular, we consider the very precise recent lattice calculations of this form factor. These new results will help to disentangle the hadronic from the nuclear effects. |
Thursday, October 25, 2018 8:15PM - 8:30PM |
EN.00006: Development of Scintillating Bolometer for Neutrinoless Double Beta Decay of 48Ca Xiaolong Li Neutrinoless double beta decay (0vDBD) search is a way to prove the Majorana nature of neutrinos and to support leptogenesis scenarios. We are developing CaF2 scintillating bolometers to search for 0vDBD of 48Ca. The scintillating bolometers measuring heat and scintillation-light signals simultaneously can achieve an excellent energy resolution and to provide a clear particle identification between beta/gamma and alpha events. The target of the R&D setup is a 300 g CaF2(Eu) crystal. The heat signals are read by a metallic magnetic calorimeter (MMC) thermally connected to a phonon collector film that is a thin metal layer evaporated on a surface of the crystal. A light detector composed of a 2 inch Ge wafer and an MMC sensor is employed just above the crystal. An above ground experiment was carried out for simultaneous detection of heat and light signals from the crystal. The measurement was compared with a Geant4 simulation of scintillation detection with realistic geometry of the detector components. It is noted that some portion of light is absorbed on the metal phonon collector. In this presentation, we report on the latest performance of the detector setup and a future plan to search for 0vDBD of 48Ca using simultaneous phonon-scintillation detection. |
Thursday, October 25, 2018 8:30PM - 8:45PM |
EN.00007: Neutrinoless double-beta decay and other rare event searches with CUORE Danielle H Speller The CUORE experiment is a ton-scale bolometric detector located deep underground in Gran Sasso National Laboratory (LNGS). Since its commissioning in May 2017, CUORE has collected over 86.3 kilogram-years of exposure, and, combined with data from Cuoricino, set a limit of 1.5e25 years on the half-life of neutrinoless double-beta decay in Te-130 (90% C.L.). In addition to being optimized for sensitivity to neutrinoless and two-neutrino double-beta decay, the CUORE experiment is sensitive to a wide array of searches for physics beyond the standard model. In this talk, we discuss the recent results and current status of the CUORE experiment. |
Thursday, October 25, 2018 8:45PM - 9:00PM |
EN.00008: Application of Cryogenic TES based Light Detectors for CUPID Bradford Welliver, Vivek Singh, Giovanni Benato, Clarence L Chang, Junjia Ding, Alexey Drobizhev, B.K. Fujikawa, Raul Hennings-Yeomans, Goran Karapetrov, Yury G Kolomensky, Laura Marini, Valentyn Novosad, John Pearson, Tomas Polakovic, Benjamin EL Schmidt, Sachinthya Wagaarachchi, Gensheng Wang, Volodymyr G Yefremenko, Benjamin J Sheff The Cryogenic Underground Observatory for Rare Events (CUORE) is a search for lepton number violating new physics currently operating at the Laboratori Nazionali del Gran Sasso (LNGS). CUORE monitors 988 TeO2 crystals (742 kg) for neutrinoless double beta decay (0νββ) by operating these crystals as cryogenic bolometers using neutron-transmutation doped (NTD) Ge thermistors. CUORE is expected to achieve a sensitivity to the 130Te 0νββ decay half-life of T1/2 = 9 x 1025 years (90% C.L.) after 5 years of operation, and has already met the expected background goals of approximately 1 cnt/keV/kg/yr. In order to further improve upon the background the CUORE Upgrade with Particle ID (CUPID) program will introduce improved radiopurity screening, enhanced target masses, and use a two channel energy collection approach (light and heat). This will allow for event by event discrimination of α and β events, enhancing the ability to reject background. In this talk I will discuss how the current R&D at LBNL and UC Berkeley with low-Tc transition edge sensors (TES) with SQUID based light detectors presents a suitable technology to meet CUPID design goals, and how such devices might be realized in the CUPID experiment. |
Thursday, October 25, 2018 9:00PM - 9:15PM |
EN.00009: Li$_{2}$MoO$_{4}$ for 0$\nu\beta\beta$ decay search in CUIPD - The Physics case and current status Benjamin Schmidt $^{100}$Mo deployed in the form of enriched Li$_{2}$MoO$_{4}$ crystals can be used as promising scintillating bolometers to search for 0$\nu\beta\beta$ in a ton-scale experiment. In this talk we will review the properties of this target crystal and achieved bolometric performance. We will also discuss its role as baseline choice for CUPID (CUORE Upgrade with Particle ID) and how it can benefit from ongoing CUPID sensor R\&D. Successful bolometric tests of enriched Li$_{2}$MoO$_{4}$ crystals showed excellent performance of $\sim$5-6 keV energy resolution (FWHM) at 2615 keV and $\sim$9 sigma alpha to beta/gamma separation at nearly full signal efficiency. Twenty enriched 0.2 kg detectors have recently been deployed in the CUPID-Mo experiment in Modane. A CUORE based analysis framework has been setup and data from its validation will be presented. With regular data taking scheduled to start in summer 2018 we expect to achieve a sensitivity on the 0$\nu\beta\beta$ half life of larger than 10$^{24}$ yr after half a year of data taking. This talk will also report on these ongoing activities. |
Thursday, October 25, 2018 9:15PM - 9:30PM |
EN.00010: NuDot: Double-Beta Decay with Direction Reconstruction in Liquid Scintillator Julieta Gruszko, Andrey Elagin, Christopher P Grant, Diana Gooding, Aobo Li, Brian Naranjo, Jonathan Ouellet, Lindley A Winslow As neutrinoless double-beta decay searches seek to reach into and beyond the inverted hierarchy regime, new strategies are needed to reject background events in kiloton-scale detectors. In monolithic liquid-scintillator-based detectors, otherwise-irreducible backgrounds like 8B solar neutrino scattering could be identified by their event topology and novel deep-learning-based algorithms. NuDot is a 1-ton prototype that aims to demonstrate Cherenkov signal momentum reconstruction of ~1 MeV beta particles. In the FlatDot test-stand, the NuDot collaboration has demonstrated the first liquid scintillator timing-based Cherenkov/scintillation light separation of < 2 MeV beta decay events, validating NuDot's photodetectors and DAQ approach. FlatDot has also allowed for tests of novel liquid scintillator cocktails, including the use of quantum dots as wavelength shifters. The NuDot detector is currently undergoing construction and commissioning at MIT. In the coming months, we will conduct surface measurements demonstrating direction reconstruction of calibration source beta events, followed by an underground measurement of two-neutrino double-beta decay with direction reconstruction.
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Thursday, October 25, 2018 9:30PM - 9:45PM |
EN.00011: Flavor Development of a Two Dimensional Dense Neutrino Gas Joshua Martin, Huaiyu Duan Dense neutrino gases occur in several astrophysical settings such as early universe cosmology and the dynamic environments surrounding compact objects like core-collapse supernovae or binary neutron star mergers. It has long been understood that in the coherent-forward-scattering regime the neutrino gas evolution results in a non-linear, flavor-dependent index of refraction for propagating neutrinos which can result in coupling between different neutrino trajectories. In one dimensional models, the neutrino gas displays large scale coherent behavior across different trajectories. However, in simple two dimensional toy models, it has been suggested that there may be significant development of kinematic decoherence of the gas. In this talk I will present results from a numerical simulation of such a dense neutrino environment in two dimensions. I will describe the evolution of the flavor content of the neutrinos and contextualize the numerical results with theory. |
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