Bulletin of the American Physical Society
2016 Fall Meeting of the APS Division of Nuclear Physics
Volume 61, Number 13
Thursday–Sunday, October 13–16, 2016; Vancouver, BC, Canada
Session NF: Neutrinoless Double Beta Decay - Theory and Experimental Techniques |
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Chair: Jason Detwiler, University of Washington Room: Pavilion Ballroom A |
Sunday, October 16, 2016 8:30AM - 8:42AM |
NF.00001: Effective operators for neutrinoless double beta decay Mihai Horoi Neutrinoless double-beta decay, if observed, would signal physics beyond the Standard Model. Guiding and analyzing the eventual neutrinoless double beta decay observations require accurate nuclear matrix elements (NME). The present status of the NME calculations indicates large discrepancies between the results of different nuclear structure models, and significant uncertainties within each model due to ingredients such as the size of the single particle space, the nuclear Hamiltonian, the choice of short range correlations, etc. In my talk I will discuss these discrepancies and uncertainties, and I will show some steps towards reducing them using effective operators. [Preview Abstract] |
Sunday, October 16, 2016 8:42AM - 8:54AM |
NF.00002: Measurement of the Transverse Diffusion of Electrons in Liquid Xenon with the EXO-200 Detector Michael Jewell The EXO-200 Collaboration is searching for neutrinoless double beta decay using a liquid xenon (LXe) time projection chamber. This measurement relies on modeling the size of charge deposits produced by interactions in the LXe to allow discrimination between signal and background events. Electron diffusion increases the size of events and can reduce the effectiveness of this discrimination. This effect is small for the current experiment, but in the next-generation ton-scale detectors used for both dark matter and double beta decay this effect will be more important. Presented here is a measurement by EXO-200 of the transverse diffusion constant of electrons at low drift fields to help better understand the transport properties of electrons in liquid xenon. [Preview Abstract] |
Sunday, October 16, 2016 8:54AM - 9:06AM |
NF.00003: Ba-ion extraction and identification from high pressure Xenon gas for nEXO Yang Lan, Thomas Brunner, Daniel Fudenberg, Victor Varentsov, Jens Dilling, Giorgio Gratta The Enriched Xenon Observatory (EXO) is searching for the lepton-number violating double beta decay ($0\nu\beta\beta$) in $^{136}$Xe. If experimentally confirmed, $0\nu\beta\beta$ will require the neutrino to be a Majorana particle, and shed light on the neutrino-mass hierarchy. The currently running EXO-200 experiment has obtained the limit of $T_{1/2}^{0\nu\beta\beta} \geq 1.1 \times 10^{25}$ years. In parallel, the development of nEXO has started and is expected to probe the inverted mass hierarchy of neutrino. One of the design goals of nEXO is to unambiguously differentiate true double beta decay events from background contributions through Ba-tagging, i.e. by identifying the daughter isotope $^{136}$Ba. With an efficient Ba-Tagging technique, the backgournds can be virtually eliminated. A setup is being developed for Ba-tagging in xenon gas. Its central component is an RF-funnel to extract Ba-ions from high pressure xenon gas (up to 10 bar). The second stage, a linear Paul trap, cools the ions through buffer gas and bunches them into a multi-reflection time-of-flight mass spectrometer for ion identification. The RF-funnel has been built and tested. The liner Paul trap is currently under development. The Ba-tagging setup will be presented and future works will be discussed. [Preview Abstract] |
Sunday, October 16, 2016 9:06AM - 9:18AM |
NF.00004: Precision energy measurement using the {\sc MAJORANA DEMONSTRATOR} Ian Guinn The {\sc Majorana Demonstrator} is seeking neutrinoless double beta decay ($0\nu\beta\beta$) in $^{76}$Ge. The $0\nu\beta\beta$ signal consists of a peak in a 4~keV region of interest (ROI) at the $^{76}$Ge double-beta decay Q-value of 2039~keV. The {\sc Demonstrator} will consist of an array of high purity germanium (HPGe) detectors with a P-type point contact (PPC) geometry. The experiment's goal is to reduce the background in the ROI to $<3$~counts/ROI-tonne-yr. Precise calculation of the energy of each event can help to shrink the size of the ROI, thus reducing the background counts. A precise measurement of the response function of the detectors is important for calculating the ROI and controlling systematic errors on the limits produced. This presentation will describe the measurement of the response function using calibration data, along with several techniques used to improve the energy calculations, such as correcting for charge trapping in detectors and digitizer non-linearities. [Preview Abstract] |
Sunday, October 16, 2016 9:18AM - 9:30AM |
NF.00005: Optimizing the CUORE data processing in search for $0\nu \beta \beta$ decay Benjamin Schmidt The search for neutrino-less double beta decay ($0\nu \beta \beta$) may allow us to understand the Dirac or Majorana nature of the neutrino, constrain its mass and provide insight into the origin of the matter-antimatter asymmetry in the Universe. The Cryogenic Underground Observatory for Rare Events (CUORE) is a $0\nu \beta \beta$ decay search experiment currently being installed deep underground at the Laboratori Nazionali del Gran Sasso (LNGS). It is going to house an array of 988 TeO$_2$ crystals with a total mass of 741 kg. It is designed to reach a sensitivity on the neutrino-less double beta decay half life of $^{130}$Te of T$_{1/2} = 9.5 \times 10^{25} \rm \;(90\% C.L.)$ after 5 years of data taking. A data analysis pipeline has been prepared and successfully used for the recently concluded prototype experiment CUORE-0. In this talk we will focus on the challenge of further automatizing and extending the processing from a single tower of 52 bolometers to the analysis of the data from 988 individual detectors. We will give an update on this work and a first evaluation of several improvements. [Preview Abstract] |
Sunday, October 16, 2016 9:30AM - 9:42AM |
NF.00006: Online Data Quality and Bad Interval Detection for the CUORE Neutrinoless Double Beta Decay Search Bradford Welliver The Cryogenic Underground Observatory for Rare Events (CUORE) is a large neutrinoless double beta decay $\left(0 \nu \beta \beta \right)$ search being installed underground at the Laboratori Nazionali del Gran Sasso (LNGS). $0 \nu \beta \beta$ searches can address fundamental questions about the nature of the neutrino, such as whether it is a Dirac or Majorana fermion, its mass scale, and may provide insight into the observed matter-antimatter asymmetry in the universe. CUORE is the largest array of bolometer instrumented crystals in the world, nineteen times larger than the previous implementation used in CUORE-0, and contains a total of 988 TeO$_2$ crystals with a mass of 741kg and is expected to achieve a sensitivity on the $^{130}$Te $0 \nu \beta \beta$ half-life of $T_{1/2} = 9.5$ 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 the determination of bad intervals of time in detector operation. We will discuss the work being performed to provide expanded online detector quality monitoring tools as well as the development of automated algorithms to test and identify periods of abnormal behavior across all of the individual detectors. [Preview Abstract] |
Sunday, October 16, 2016 9:42AM - 9:54AM |
NF.00007: Characterizing Scintillation and Cherenkov Light in Water-Based Liquid Scintillators Benjamin Land, Javier Caravaca, Freija Descamps, Gabriel Orebi Gann The recent development of Water-based Liquid Scintillator (WbLS) has made it possible to produce scintillating materials with highly tunable light yields and excellent optical clarity. This allows for a straightforward combination of the directional properties of Cherenkov light with the greater energy resolution afforded by the typically brighter scintillation light which lends itself well to a broad program of neutrino physics. Here we explore the light yields and time profiles of WbLS materials in development for Theia (formerly ASDC) as measured in CheSS: our bench-top Cherenkov and scintillation separation R\&D project at Berkeley Lab. [Preview Abstract] |
Sunday, October 16, 2016 9:54AM - 10:06AM |
NF.00008: Characterization of Silicon Photomultipliers for the nEXO experiment Luca Doria The search for the neutrinoless double beta decay represents a test of the Majorana nature of neutrinos and at the same time a test of lepton number conservation. Building on the experience gained with the EXO-200 experiment, nEXO is a next generation detector designed for searching neutrinoless double beta decay events with a 5 tonne liquid Xenon time projection chamber (TPC). The detection of this decay requires a very low background experimental setup and excellent energy resolution. In a TPC, both scintillation and ionization signals are detected. For detecting scintillation light from Xenon, silicon photomultipliers (SiPM) represent the currently considered technology. For identifying the appropriate device meeting the nEXO requirements, different state of the art SiPMs are presently characterized using the TRIUMF setup. We will present results on SiPM characterizations regarding their main characteristics: dark noise, afterpulsing and photodetection efficiency in different experimental conditions. References: [1] https://nexo.llnl.gov/ [2] I. Ostrovskiy et al., Nuclear Science, IEEE Tr. , vol.62, no.4, pp.1825,1836 (2015). [Preview Abstract] |
Sunday, October 16, 2016 10:06AM - 10:18AM |
NF.00009: Characterization of single layer anti-reflective coatings for Ge and Si substrates and their potential use in low-background detectors Erin Hansen Scintillating materials can be used to significantly reduce charged particle backgrounds in low-temperature bolometer-based rare-event searches; the ratio of signals from heat and light can identify charged particles as they pass through the detector. A second bolometer is introduced for light collection, typically made of Si or Ge whose indices of refraction cause an inherent loss due to reflections of incoming light. Antireflective coatings can be used to minimize this loss of sensitivity. Coatings of SiO$_2$, HfO$_2$, and TiO$_2$ were manufactured, and SiO$_2$ coatings were characterized at room temperature. Preliminary calculations suggest a decrease in reflection due to these coatings; non-normal incidence is also considered. Further tests for low temperature behavior are ongoing. [Preview Abstract] |
Sunday, October 16, 2016 10:18AM - 10:30AM |
NF.00010: Improving the energy calibration of CUORE-0 and CUORE Jeremy S. 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-0, an experiment using a single CUORE-like tower, completed physics data-taking in 2015 and set a new limit on the $0\nu\beta\beta$ decay half-life of $^{130}$Te. CUORE installation is scheduled to be completed this year with commissioning and data taking to begin soon thereafter. I will discuss the analysis and results from CUORE-0, focusing on energy calibration, and the analysis techniques and calibration hardware that will allow us to improve our understanding of the detector energy scale in CUORE. [Preview Abstract] |
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