Bulletin of the American Physical Society
4th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 59, Number 10
Tuesday–Saturday, October 7–11, 2014; Waikoloa, Hawaii
Session 1WM: Neutrinoless Double Beta Decay Experiments and Underground Physics Challenges I |
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Chair: Kevin Lesko, Lawrence Berkeley National Laboratory Room: Kona 5 |
Tuesday, October 7, 2014 9:00AM - 9:30AM |
1WM.00001: TBD Invited Speaker: Masataka Fukugita . [Preview Abstract] |
Tuesday, October 7, 2014 9:30AM - 10:00AM |
1WM.00002: The Majorana Neutrinoless Double-Beta Decay Program Invited Speaker: Vincente Guiseppe Neutrinoless double-beta decay searches play a major role in determining the nature of neutrinos, the existence of a lepton violating process, and the effective Majorana neutrino mass. The {\sc Majorana} Collaboration is assembling an array of high purity Ge detectors to search for neutrinoless double-beta decay in $^{76}$Ge. The {\sc Majorana} {\sc Demonstrator}, containing 40 kg (30 kg enriched in $^{76}$Ge) of Ge detectors, is currently being constructed and commissioned at the Sanford Underground Research Facility in Lead, South Dakota. The initial goals are to demonstrate the required background and scalability of a Ge-based, tonne-scale experiment. The status and potential physics reach of the {\sc Majorana} {\sc Demonstrator} experiment will be presented. [Preview Abstract] |
Tuesday, October 7, 2014 10:00AM - 10:30AM |
1WM.00003: Upgrades for GERDA Phase II Invited Speaker: Mark Heisel The Germanium Detector Array (GERDA) experiment is searching for the neutrinoless double beta decay ($0\nu\beta\beta$) of $^{76}$Ge. It is a process that violates lepton number conservation and is predicted to occur in extensions of the standard model of particle physics. GERDA is located underground in the Gran Sasso National Laboratory (LNGS), Italy. An array of bare high-purity germanium detectors enriched in $^{76}$Ge is operated in a cryostat with 64 m$^3$ of liquid argon supplemented by a 3 m thick shield of water. The experiment aims at exploring the $0\nu\beta\beta$ decay up to a half life of $2\cdot10^{26}$ yr in two phases: Phase I of the experiment has been concluded last year. No signal is observed and the so far best limit is derived for the half life of the $0\nu\beta\beta$ decay of $^{76}$Ge, $T_{1/2}^{0\nu}\leq2.1\cdot10^{25}$ yr (90\% C.L.), after an exposure of $21.6 $kg$\cdot$yr. The result refutes an earlier claim of discovery with high probability. The background index of $1\cdot10^{-2}$ cts/(keV$\cdot$kg$\cdot$yr) is lower by about one order of magnitude compared to previous experiments. At present the experiment is being upgraded to Phase II. The aim is to collect an exposure of $100 $kg$\cdot$yr and further reduce the background by another order of magnitude to a level of $\leq10^{-3}$ cts/(keV$\cdot$kg$\cdot$yr). The detector mass will be increased by $\sim$20 kg of new Broad Energy Germanium (BEGe) detectors from enriched $^{76}$Ge, which exhibit superior pulse shape discrimination and hence background rejection power. Low mass detector holders, cold front-end electronics, contacting and cabling schemes are redesigned for ultra low mass and radiopurity. In addition, a retractable liquid argon veto will be installed to efficiently suppress background events that induce scintillation in the liquid argon. A hybrid solution of photomultiplier tubes and silicon photomultipliers coupled to scintillating fibres was chosen. This talk gives an account of the results and these challenging modifications to meet our design goals. [Preview Abstract] |
Tuesday, October 7, 2014 10:30AM - 11:00AM |
1WM.00004: COFFEE BREAK |
Tuesday, October 7, 2014 11:00AM - 11:30AM |
1WM.00005: Results from CUORE-0, Status of CUORE Invited Speaker: Reina Maruyama CUORE is a double beta decay experiment based on large-scale cryogenic bolometers currently under construction at the Gran Sasso National Laboratory (LNGS). Its primary aim is to observe neutrinoless double beta decay and measure Majorana neutrino masses with a projected sensitivity to probe the so-called inverted mass hierarchy. In this talk, I will review the results from CUORE-0 and discuss the physics potential and construction efforts of CUORE. I will also summarize the R\&D efforts underway to extend the reach of bolometer-based detectors for future generation double-beta decay experiments. [Preview Abstract] |
Tuesday, October 7, 2014 11:30AM - 12:00PM |
1WM.00006: The EXO Search for Neutrinoless Double Beta Decay Invited Speaker: Kevin Graham The Enriched Xenon Observatory (EXO) collaboration continues to develop techniques and technology towards the search for neutrinoless double beta decay. Since 2010 the collaboration has been operating a liquid-phase time project chamber, EXO-200, at WIPP in New Mexico. Data collected with this experiment has led to several physics results and demonstrated the feasibility of the approach. Design and R{\&}D efforts are underway to develop the next-generation double beta decay experiment, nEXO, which will utilize approximately 5 tonnes of enriched xenon. In this talk, the latest results from the EXO-200 will be summarized and update on the developments towards the nEXO experiment will be provided. [Preview Abstract] |
Tuesday, October 7, 2014 12:00PM - 12:30PM |
1WM.00007: KamLAND Zen Invited Speaker: Koji Ishidoshiro KamLAND-Zen is an experiment for neutrinoless double beta decay search with xenon 136 based on large liquid scintillator detector KamLAND. The first phase of the experiment was operated from Oct. 12, 2011 to June 14, 2012 and we set lower limit for the neutrino-less double beta decay half-life , $T_{1/2}(0\nu) > 1.9\times 10^{25} $yr. The combined result of KamLAND-Zen and EXO data give $T_{1/2}(0\nu) > 3.4 \times 10^{25} $yr. At the first phase, we found problematic background, 110mAg. Then we purified liquid scintillator and xenon gas by distillation to remove the background. The purification campaign was started just after the first phase and ended at Dec. 2013. We present current status and latest results from KamLAND-Zen second phase, and discuss the future prospects. [Preview Abstract] |
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