Bulletin of the American Physical Society
2006 APS April Meeting
Saturday–Tuesday, April 22–25, 2006; Dallas, TX
Session J9: Double Beta Decay |
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Sponsoring Units: DNP Chair: Andrew Hime, Los Alamos National Laboratory Room: Hyatt Regency Dallas Cumberland B |
Sunday, April 23, 2006 1:15PM - 1:27PM |
J9.00001: Status of EXO-200 Francisco LePort EXO-200 (Enriched Xenon Observatory-200kg) is an experiment designed to detect the double-beta decay of $^{136}$Xe. It will use 200 kg of Xe, isotopically enriched to 80{\%} in $^{136}$Xe, which is currently on hand at Stanford University. The Xe will be used as an active medium in the detector, and will be contained in liquid form in an ultra-low background, TPC. EXO-200 will be the first low-background detector to make large-scale use of Large Area Avalanche Photodiodes (LAAPDs), used to collect scintillation light. The simultaneous collection of ionization charge and scintillation light for every event has been proven to dramatically improve energy resolution. EXO-200 will be housed under a $\sim $2000 meter water-equivalent overburden at WIPP, New Mexico. Once completed, it will be the largest running double-beta decay experiment. It is designed to achieve competitive sensitivity for the neutrinoless double-beta decay mode (0$\nu \beta \beta )$, as well as measure the as yet unobserved two neutrino double-beta decay mode (2$\nu \beta \beta )$ of $^{136}$Xe. [Preview Abstract] |
Sunday, April 23, 2006 1:27PM - 1:39PM |
J9.00002: A linear ion trap for the Enriched Xenon Observatory EXO Bj\"orn Flatt, Ralph DeVoe, Giorgio Gratta, Matthew Green, Jesse Wodin The Enriched Xenon Observatory for double beta decay attempts to answer one of the greatest outstanding questions in neutrino physics by performing a direct measurement of the majorana neutrino mass through the investigation of neutrinoless double beta decay ($0\nu \beta\beta$) of $^{136}$Xe. The major advantage of Xenon as a source is the ability to detect the Ba ion daughter directly through laser induced fluorescence spectroscopy; this technique would allow for an essentially background-free measurement. First investigations of Ba spectroscopy were done in a hyperbolic Paul-trap. This talk discusses the trapping of single barium ions in buffer gasses, as well as the design and implementation of a linear ion trap, which allows for external loading of ions, for use in the Barium tagging aspect of a liquid Xenon double beta decay experiment. [Preview Abstract] |
Sunday, April 23, 2006 1:39PM - 1:51PM |
J9.00003: Pulse Shape and Segmentation Analysis in Germanium Detectors for Double-Beta Decay Victor M. Gehman, Steven Elliott, Dongming Mei, Albert Young, Henning Back The Majorana Project will endeavor to provide direct limits on the effective Majorana mass of the electron neutrino through the measurement of neutrinoless double-beta decay in $^{76}$Ge. Our goal is an experiment sensitive to the effective neutrino mass at the level of a few hundred meV scalable to a sensitivity of approximately 50 meV. One technique the Majorana Project will exploit to separate signal from background events is the combination of pulse shape analysis and detector segmentation. This background reduction is possible because double-beta events are very spatially localized (or single-site) in a germanium detector array, whereas likely backgrounds will be more spatially extended (or multi-site). In this report, we present a series of experiments using double-escape peaks as surrogate single-site events and full-energy $\gamma$ peaks as surrogate multi-site events. These data were taken at LANL using a ``CLOVER'' detector (an array of four 800g, two-fold segmented germanium detectors) with a $^{56}$Co source. We will also discuss a similar experiment performed using the Free Electron Laser at TUNL and SEGA (a twelve-fold segmented detector enriched to 86\% in $^{76}$Ge). [Preview Abstract] |
Sunday, April 23, 2006 1:51PM - 2:03PM |
J9.00004: Neutron-induced Background for Double-Beta Decay Experiments via Inelastic Scattering Processes Dongming Mei, Steve Elliotts, Victor Gehman, Andrew Hime, Kareem Kazkaz We investigate several $Pb(n,n'\gamma)$ and $Ge(n,n'\gamma)$ reactions using a segmented clover detector. With and without an AmBe neutron source, we can separate the 2615-keV $\gamma$-ray produced from the $^{208}Pb(n,n'\gamma$) reaction from the more familiar $^{208}$Tl decay. The detection rate of the 2615-keV $\gamma$-ray produced via the $^{208}Pb(n,n'\gamma$) reaction is determined. We emphasize that the 2615-keV $\gamma$-ray and the other high energy $\gamma$-rays from $Pb(n,n'\gamma$) reactions can be a significant background for double beta decay experiments which use lead as a massive inner shielding and the background level depends on the depth of a specific underground laboratory. The excitation $\gamma$-ray lines through $Ge(n,n'\gamma)$ reactions are also observed. We consider the contribution of such backgrounds and the limitation in sensitivity of next generation searches for neutrinoless double beta decay using enriched germanium detectors and develop the the depth requirements of such detectors under different shielding configurations. [Preview Abstract] |
Sunday, April 23, 2006 2:03PM - 2:15PM |
J9.00005: An update on the Majorana-Gerda simulation package (MaGe) Michael Marino The Majorana collaboration is proposing to build an experiment to search for neutrinoless double-beta decay ($0\nu \beta \beta$) from $^{76}$Ge using segmented HPGe detectors. The collaboration has partnered with the Gerda collaboration\footnote{Gerda Collaboration, Proposal to LNGS, available (12 Jan 2006) http://www.mpi-hd.mpg.de/ge76/proposal\_21sept.pdf} to create a joint simulation package (MaGe) based upon CERN's Geant4\footnote{Geant4 - A Simulation Toolkit, Nuclear Instruments and Methods A 506 (2003) 250-303} simulation engine and Root\footnote{ROOT - An Object Oriented Data Analysis Framework, Nuclear Instruments and Methods A 389 (1997) 81-86} analysis software. MaGe provides an adaptable and comprehensive simulation environment to model detector response, pulse formation, and background processes for a variety of detector parameters and geometries. This presentation will include an introduction to the important components of MaGe and present the latest results for background simulations of the Majorana reference design as well as its expected sensitivity to $0\nu \beta \beta$ decay of $^{76}$Ge. A complementary talk will be given addressing verification of the simulation package. [Preview Abstract] |
Sunday, April 23, 2006 2:15PM - 2:27PM |
J9.00006: Verification of the Majorana-Gerda Simulation Package (MaGe) A. G. Schubert Determining whether neutrinos are Majorana or Dirac particles is of vital importance to the physics community. The Majorana experiment seeks to address this question by searching for neutrinoless double-beta decay using germanium crystals enriched in $^{76}$Ge. The Majorana and Gerda\footnote{The Gerda Collaboration, Gerda. (2004) 12 Jan 2006 http://www.mpi-hd.mpg.de/ge76/proposal\_21sept.pdf} collaborations have jointly developed MaGe, a Geant4\footnote{S. Agnostinelli et al., Geant4 - A Simulation Toolkit. Nucl. Instr. and Meth. {\bf A 506} (2003), 250} and ROOT\footnote{Brun, R. and F. Rademakers, ROOT - An Object Oriented Data Analysis Framework. Nucl. Instr. and Meth. {\bf A 389} (1997), 81} based simulation framework, to aid in the design and analysis phases of both experiments. Several Monte Carlo studies of existing detectors were performed using the MaGe package. Comparisons between the experimental data and the simulation results are used to verify MaGe's performance. The simulations that will be discussed are a study of neutron production from a SLAC e$^{-}$ beam experiment\footnote{S. Taniguchi et al. Nucl. Instr. and Meth. {\bf A 503} (2003), 595}, studies of a PNNL low- background HPGe material sampling detector with multiple sources, and a study of a LANL HPGe Clover detector with an AmBe source. This work is supported by the DOE Office of Nuclear Physics. [Preview Abstract] |
Sunday, April 23, 2006 2:27PM - 2:39PM |
J9.00007: Updates on Cuoricino and CUORE Thomas D. Gutierrez Overviews of the neutrinoless double beta ($\beta\beta0\nu$) decay experiments Cuoricino and CUORE (Cryogenic Underground Observatory for Rare Events) will be presented. Cuoricino is currently the largest double beta decay experiment in operation and consists of 40 kg of TeO$_2$ crystals that act both as source and detector. The proposed CUORE experiment will consist of 988 TeO$_2$ crystals with a total source/detector mass of 750 kg. Updates from Cuoricino on the $\beta\beta0\nu$ limit for $^{130}$Te as well as evaluations of other decays will be presented. [Preview Abstract] |
Sunday, April 23, 2006 2:39PM - 2:51PM |
J9.00008: A Search For Two-Neutrino Double-Beta Decay of $^{130}Te$ To The First Excited $0^{+}$ State in $^{130}Xe$ With The CUORICINO Detector Iulian Bandac We will discuss the results of an experimental search for two-neutrino $\beta\beta$ decay of $^{130}Te$ to the first excited $0^{+}$ state in $^{130}Xe$ using the data from the CUORICINO detector. The CUORICINO array consists of $44$ cubic crystals of $TeO_{2}$ $5\times 5\times 5 \textrm{ cm}^{3}$ of natural concentration $33.8\%$ and $18$ crystals $3\times 3\times 6\textrm{ cm}^{3}$ four of them being isotopically enriched, two in $^{130}Te$ and the other two in $^{128}Te$. The detector is operated in the Gran Sasso Underground Laboratory in Assergi, Italy at a depth of about $3500$ m.w.e. We are considering different scenarios by searching for coincidences between different neighboring detectors. First we look for all events that are between the threshold and the maximum energy for the two emitted electrons $739.5$ keV and for which there is one or more coincidences. Then among these select those for which their energy summed to $1793.5\pm 100$ keV. These will include all events in which both gamma rays completely escape from the detector. Then we demand a triple coincidence leading to a background almost zero. In this way we can put a best bound on, or measure the half life. [Preview Abstract] |
Sunday, April 23, 2006 2:51PM - 3:03PM |
J9.00009: Status of CUORE: Bolometric Search for Neutrinoless Double Beta Decay Reina Maruyama CUORE is a bolometric neutrinoless double beta decay experiment currently under development at Gran Sasso National Laboratory. It will consist of 988 TeO$_2$ crystals weighing a total of 750 kg. The primary goal is to look for neutrinoless double beta decay of Te-130. Most experimental techniques have been demonstrated in the currently running prototype Cuoricino, however a few technical challenges remain. The key to the success for CUORE lies in ensuring ultra-low radioactive backgrounds in the detector and having well-characterized uniform thermistors for each crystal to measure the energy deposited from a nuclear decay. Recent R\&D developments for CUORE will be discussed, including background studies and thermistor production. [Preview Abstract] |
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