Bulletin of the American Physical Society
2017 Fall Meeting of the APS Division of Nuclear Physics
Volume 62, Number 11
Wednesday–Saturday, October 25–28, 2017; Pittsburgh, Pennsylvania
Session FH: Neutrinoless Double Beta Decay |
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Chair: Vincente Guiseppe, University of South Carolina Room: Marquis B |
Thursday, October 26, 2017 4:00PM - 4:12PM |
FH.00001: Alpha Background Discrimination in the MAJORANA DEMONSTRATOR Julieta Gruszko The \textsc{Majorana Demonstrator} (MJD) searches for neutrinoless double-beta decay of $^{\mathrm{76}}$Ge using arrays of high-purity germanium detectors. If observed, this process would have implications for grand-unification and the predominance of matter over antimatter in the universe. A problematic background in such large granular detector arrays is posed by alpha particles. In MJD, potential background events that are consistent with energy-degraded alphas originating on the passivated detector surface have been observed. We have studied these events by scanning the passivated surface of a P-type point contact detector like those used in MJD with a collimated alpha source. We observe that surface alpha events exhibit high charge-trapping, with a significant fraction of the trapped charge being re-released slowly. This leads to both a reduced prompt signal and a measurable change in slope of the tail of a recorded pulse. In this contribution we discuss the characteristics of these events and the filter developed to identify the occurrence of this delayed charge recovery, allowing for the efficient rejection of passivated surface alpha events while retaining 99.8{\%} of bulk events. We also discuss the impact of this filter on the sensitivity of MJD. [Preview Abstract] |
Thursday, October 26, 2017 4:12PM - 4:24PM |
FH.00002: CORC: An Online Data Quality Tool For CUORE Bradford Welliver The Cryogenic Underground Observatory for Rare Events (CUORE) is a large neutrinoless double beta decay search experiment. Currently CUORE is actively taking data at the Laboratori Nazionali del Gran Sasso (LNGS). These searches can address fundamental questions about the nature of the neutrino and may provide insight into the observed matter-antimatter asymmetry in the universe leading to beyond standard model physics via lepton number violation. CUORE is the largest array of crystal bolometers in the world, containing a total of 988 TeO$_2$ crystals with a mass of 742kg and is expected to achieve a sensitivity on the $^{130}$Te $0 \nu \beta \beta$ half-life of $T_{1/2} = 9$ x $10^{25}$ years (90 \% C.L.) after 5 years of operation. The large number of individual crystals in CUORE presents challenges for monitoring data quality and determination of time periods of detector behavior suitable for analysis. We will discuss the current state of the online run diagnostic system that allows for easy monitoring of all crystals, provides an overview of performance over time, and gives an ability to set flags for periods of bad detector behavior as well as set phone and email alarms on various cryostat parameters. [Preview Abstract] |
Thursday, October 26, 2017 4:24PM - 4:36PM |
FH.00003: CUORE data taking and performance Danielle Speller The Cryogenic Underground Observatory for Rare Events --CUORE-- is a tonne-scale low-background, bolometric experiment searching for neutrinoless double beta decay in $^{130}$Te and weak-scale physics beyond the standard model. Located in Italy's Gran Sasso National Laboratory, commissioning of the full array of 988 TeO$_{2}$ crystals was completed in Spring 2017, and data-taking is now underway. In this talk, we will discuss the progress of CUORE data collection and current detector performance. [Preview Abstract] |
Thursday, October 26, 2017 4:36PM - 4:48PM |
FH.00004: CUORE Spectrum and Background Christopher Davis The Cryogenic Underground Observatory for Rare Events (CUORE) is a neutrinoless double-beta decay experiment at the Laboratori Nazionali del Gran Sasso (LNGS). CUORE is performing this search in $^{\mathrm{130}}$Te by using 988 TeO$_{\mathrm{2}}$ bolometric crystals arranged in 19 towers inside of a cryostat operating below 20 mK. In this talk, I will discuss the measured background in the CUORE experiment and simulations of the background model, critical parts leading towards a measurement of two-neutrino double-beta decay. [Preview Abstract] |
Thursday, October 26, 2017 4:48PM - 5:00PM |
FH.00005: CUORE and Background Reduction Case Studies for CUPID Michinari Sakai, Nihal Gozlukluoglu, Huan Huang CUORE (Cryogenic Underground Observatory for Rare Events) is a bolometric experiment at cryogenic temperatures currently in operation to search for neutrinoless double beta decay. Successful detection of this extremely rare process requires stringent control of radioactive backgrounds of the experiment as well as the detector itself. Great care was taken in CUORE to select the materials and various parts that comprise the current detector. However next-generation neutrinoless double beta decay experiments face a challenge to further reduce backgrounds in order to probe more deeply into the effective Majorana neutrino mass phase space. In this presentation we will review the sensitivity and background budget for the currently running experiment CUORE, as well as the target sensitivity and background goals for the next generation experiment CUPID that will cover the inverted neutrino mass hierarchy. We will explore simulation based R\&D case studies for background reduction and lay out achievable background reduction levels using possible materials and feasible geometries in the context of CUPID. [Preview Abstract] |
Thursday, October 26, 2017 5:00PM - 5:12PM |
FH.00006: Search for Neutrinoless $\beta^+/EC$ Decay of $^{120}$Te with CUORE-0 Data Giovanni Benato Neutrinoless $\beta^+/EC$ decay is a process beyond the Standard Model which violates the total lepton number conservation and would prove that neutrinos have a Majorana mass component. We present a search for the neutrinoless $\beta^+/EC$ of $^{120}$Te using CUORE-0 data. We developed a new analysis method involving the simultaneous fit of signatures with different multiplicities, and of data subsets with different background and/or signal efficiency. We obtain a limit on the half life of the decay of T$_{1/2}>1.7\cdot10^{21}$~yr at $90\%$~credible interval (C.I.), or T$_{1/2}>2.7\cdot10^{21}$~yr ($90\%$~C.I.) if combined with the Cuoricino result. This analysis procedure can be directly applied to the CUORE data, once they are available, yielding an increase in sensitivity of two orders of magnitude thanks to the larger mass and higher containment efficiency for high-multiplicity events. [Preview Abstract] |
Thursday, October 26, 2017 5:12PM - 5:24PM |
FH.00007: Neutrinoless double-beta decay search results from CUORE Jeremy Cushman The Cryogenic Underground Observatory for Rare Events (CUORE) is a ton-scale cryogenic experiment designed to search for neutrinoless double-beta ($0\nu\beta\beta$) decay of $^{130}$Te. The experiment consists of 988 ultracold TeO$_2$ bolometric crystals arranged into 19 towers, which act as both the $0\nu\beta\beta$ decay sources and detectors. CUORE began taking data in the spring of 2017. We will discuss the early neutrinoless doube-beta decay search results from CUORE, focusing on energy calibration and our understanding of the detector energy scale and resolution in CUORE. [Preview Abstract] |
Thursday, October 26, 2017 5:24PM - 5:36PM |
FH.00008: Latest Results from EXO-200 Lisa Kaufman The EXO-200 experiment has made both the first observation of the double beta decay in Xe-136 and the most precisely measured half-life of any two-neutrino double beta decay to date. Consisting of an extremely low-background time projection chamber filled with \textasciitilde 150 kg of enriched liquid Xe-136, it has provided one of the most sensitive searches for the neutrinoless double beta decay using the first two years of data. After a hiatus in operations during a temporary shutdown of its host facility, the Waste Isolation Pilot Plant, the experiment has restarted data taking with upgrades to its front-end electronics and a radon suppression system. This talk will cover the latest results of the collaboration including new data with improved energy resolution. [Preview Abstract] |
Thursday, October 26, 2017 5:36PM - 5:48PM |
FH.00009: Pulse Shape Discrimination in the MAJORANA DEMONSTRATOR Christopher Haufe The MAJORANA DEMONSTRATOR is an experiment constructed to search for neutrinoless double-beta decays in germanium-76 and to demonstrate the feasibility to deploy a large-scale experiment in a phased and modular fashion. It consists of two modular arrays of natural and 76Ge-enriched germanium p-type point contact detectors totaling 44.1 kg, located at the 4850' level of the Sanford Underground Research Facility in Lead, South Dakota, USA. A large effort is underway to analyze the data currently being taken by the DEMONSTRATOR. Key components of this effort are analysis tools that allow for pulse shape discrimination---techniques that significantly reduce background levels in the neutrinoless double-beta decay region of interest. These tools are able to identify and reject multi-site events from Compton scattering as well as events from alpha particle interactions. This work serves as an overview for these analysis tools and highlights the unique advantages that the HPGe p-type point contact detector provides to pulse shape discrimination. [Preview Abstract] |
Thursday, October 26, 2017 5:48PM - 6:00PM |
FH.00010: Neutron Inelastic Scattering on 134Xe at En = 5 - 8 MeV Mary Kidd, Werner Tornow, Sean Finch, FNU Krishichayan, Megha Bhike Neutrinoless double-beta decay (0$\nu\beta\beta$) studies are both the best way to determine the Majorana nature of the neutrino and determine its effective mass. The two main experiments searching for 0$\nu\beta\beta$-decay of $^{136}$Xe (Q value = 2457.8 keV) are Kamland-Zen and EXO-200. Though both experiments have enriched $^{136}$Xe targets, these targets still contain significant quantities of $^{134}$Xe. Recently, a new nuclear level was discovered in $^{134}$Xe that decays to the ground state emitting a 2485.7 keV gamma ray [1]. The $\gamma$-ray production cross section for this branch was found to be on the order of 10 mb for incident neutron energies of 2.5 – 4.5 MeV. Here, we have extended the investigation of this level to higher incident neutron energies, and further explore the potential neutron-induced backgrounds on both $^{134}$Xe and $^{136}$Xe for extended neutron energies. We will report our preliminary results for neutron inelastic scattering on $^{134}$Xe in applications to 0$\nu\beta\beta$ decay searches. [1] E.E. Peters, et al., EPJ Web of Conferences, 93, 01027 (2015). [Preview Abstract] |
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