Bulletin of the American Physical Society
APS April Meeting 2013
Volume 58, Number 4
Saturday–Tuesday, April 13–16, 2013; Denver, Colorado
Session D9: Double-beta Decay |
Hide Abstracts |
Sponsoring Units: DNP Chair: Tomasz Wachala, Colorado State University Room: Governor's Square 11 |
Saturday, April 13, 2013 3:30PM - 3:42PM |
D9.00001: Search for 0$\nu\beta\beta$ with CUORE: Preliminary results from CUORE-0 Jonathan Ouellet The Cryogenic Underground Observatory for Rare Events (CUORE) is a next generation bolometric detector searching for neutrinoless double beta decay (0$\nu\beta\beta$) and other rare processes operated in Gran Sasso National Laboratories in Italy. Its predecessor, Cuoricino, set the most stringent limits on the 0$\nu\beta\beta$ half-life in $^{130}$Te to date, at $T_{1/2}\geq2.8\times10^{24}$ yr (90\% C.L.). CUORE will have an active mass nearly 20 times larger and an anticipated background nearly 20 times lower, providing a sensitivity to 0$\nu\beta\beta$ half-life of $T_{1/2} > 1.6 \times 10^{26}$ yr (68\% C.L.) after 5 years of run time. This is achieved through improved bolometer handling techniques, improved bolometer-thermistor coupling, thermistor instrumentation and material radiopurity. CUORE-0, the first of 20 towers for CUORE is currently operating in the old Couricino cryostat and began data taking in October 2012. CUORE-0 will surpass the limits set by Cuoricino after less than a year of run time. Here we present early performance results from CUORE-0: detector resolutions, backgrounds, and efficiencies. [Preview Abstract] |
Saturday, April 13, 2013 3:42PM - 3:54PM |
D9.00002: Design, fabrication, and testing of the CUORE detector calibration system Adam Dally CUORE, the Cryogenic Underground Observatory for Rare Events, is a neutrinoless double beta decay experiment with an active mass of 206 kg of $^{130}$Te. The detector consists of 988 TeO$_{2}$ bolometers operating at 10 mK. The signature of 0$\nu \beta \beta $ decay is an excess of events at the Q-value of 2528 keV. Understanding the energy response is critical for event identification, but this presents many challenges. The detector requires ultra-low background radiation, vacuum compatible materials, and cryogenic temperatures. Individual energy calibration of the bolometers is achieved by placing radioactive sources between detectors inside the cryostat. A source deployment and thermalization system that meets the background and thermal requirements of the CUORE experiment has been developed. This talk will discuss the design, fabrication, and testing of the CUORE detector calibration system. [Preview Abstract] |
Saturday, April 13, 2013 3:54PM - 4:06PM |
D9.00003: EXO - Status of Ba tagging R{\&}D activities Michal Tarka The Enriched Xenon Observatory (EXO) is a low-background experiment searching for the neutrinoless double beta decay (0vbb) of Xe136 using a Time Projection Chamber (TPC). The 0vbb decay is currently the only way to test the Majorana nature of neutrinos. The EXO-200 experiment is located at the Waste Isolation Pilot Plant (WIPP, 1600 m.w.e. overburden) in New Mexico and has been running since May 2011 with 175 kg of liquid Xe enriched to 80{\%}. With a background index of 1.5 $\times$ 10$^{-3}$ counts/kg/year/keV in the region of interest around the end point of the bb decay of Xe-136, the setup has set a lower limit for 0nbb of T $_{1/2}$ \textgreater\ 1.6 $\times$ 10$^{25}$ years (90{\%} CL). The Ba-136 resulting from the bb decay of Xe-136 could be used for bb event identification against background and the development of an efficient Ba tagging technique is one of the long-term goals of the EXO collaboration. Ba tagging could virtually eliminate background thus boosting the senitivity of the experiment. This talk will outline the Ba tagging activities performed by the EXO collaboration and present the latest progress and results towards an efficient and reliable Ba tagging system. [Preview Abstract] |
Saturday, April 13, 2013 4:06PM - 4:18PM |
D9.00004: Using EXO-200 Results to Make Background Projections for the Next Generation EXO Detector (nEXO) Tessa Johnson Observation of neutrino-less double beta decay would provide a window to new physics, specifically answering questions on the true nature and absolute mass of the neutrino and the validity of lepton number conservation in the Standard Model. The EXO (Enriched Xenon Observatory) collaboration has set a limit on the half-life of this extremely rare decay and continues to take data with the current generation of the experiment, EXO-200, which uses 200 kg of xenon that has been enriched to 80\% $^{136}$Xe. In order to probe inverted mass hierarchy for neutrinos, it is necessary to build a bigger detector that will have a greater sensitivity to the neutrino-less double beta decay half-life. The next generation of the EXO experiment, dubbed nEXO, is proposed to include a time projection chamber that holds about 5,000 kg of liquid xenon. The main questions to be answered at this stage are what backgrounds will be encountered and how they will affect the physics capabilities with a detector of this magnitude. Data from EXO-200 was used to help determine potential backgrounds from detector materials, shielding materials, and mine rock. This information was used to simulate the backgrounds of nEXO and to estimate its physics reach. [Preview Abstract] |
Saturday, April 13, 2013 4:18PM - 4:30PM |
D9.00005: EXO-200: Detector Performance and neutrinoless double-beta decay search results Wolfhart Feldmeier Neutrinoless double-beta decay provides a strong probe of physics beyond the standard model. The observation of such a process would establish that the neutrino and the anti-neutrino are the same particle - a so called Majorana particle - and would help determine the absolute mass scale of the neutrino. The Enriched Xenon Observatory (EXO) is an experimental programme designed to search for neutrinoless double beta decay of Xenon 136. Its current phase, EXO-200, consists of a time projection chamber with an active mass of more than 100 kg of liquid Xenon enriched to $\sim$80\%. The system is situated at the Waste Isolation Pilot Plant in New Mexico and is continually taking data since early May 2011. The first search with an exposure of 32.5 kg-yr observed no signal with a background rate of 1.5E-3 counts/kg/yr/keV in the ?1 sigma region of interest. This sets a lower limit on the half-life of the neutrinoless double-beta decay T1/2 (136Xe) $>$ 1.6E25 yr (90\% CL), which translates into an effective light Majorana neutrino mass of less than 140 - 380 meV, depending on the matrix element calculation. This talk will discuss the performance of the EXO-200 detector and its latest physics results. [Preview Abstract] |
Saturday, April 13, 2013 4:30PM - 4:42PM |
D9.00006: A background model for the MAJORANA low-background broad energy germanium detector Alexis Schubert The MAJORANA Collaboration will search for neutrinoless double-beta decay of germanium-76 with an array of enriched germanium detectors called the DEMONSTRATOR. MAJORANA Collaborators operate a low-background research and development detector in a shielded environment at the Kimballton Underground Research Facility near Ripplemeade, Virginia. The contents of the detector cryostat are well known, making it a good candidate for testing the MAJORANA background model. This talk describes the creation of a background energy-spectrum model for the Kimballton detector. Energy spectra measured with the detector at Kimballton are compared to results of the background model, and implications for the DEMONSTRATOR are explored. [Preview Abstract] |
Saturday, April 13, 2013 4:42PM - 4:54PM |
D9.00007: Determination of the Crystal Axis Orientations of Ge detectors for the \textsc{Majorana} \textsc{Demonstrator} Wenqin Xu, Matthew Busch, Steven Elliott, Matthew Green, Alex Hegai, Reyco Henning, Michael Ronquest, Kyle Snavely, Ari Zitin High purity germanium (HPGe) crystals will be used for the \textsc{Majorana} \textsc{Demonstrator}, where they serve as both the source and the detector for neutrinoless double beta decays. Sophisticated pulse shape analysis (PSA) is crucial in distinguishing certain background events in the energy region of interest. It is also well known that the charge-carrier mobility in Ge crystals has considerable dependence on the crystallographic axes, resulting in a crystal axis dependence of the PSA. Meanwhile, as within the Peccei-Quinn solution to the strong CP problem and as a dark matter candidate, axions have been searched for in many experiments. It has been suggested that the postulated solar axions could coherently covert to photons by the Primakeoff effect in a periodic lattice, such as that found in the Ge crystals used by the \textsc{Demonstrator}, with conversion rates depending on the crystal axis orientation. In order to use the \textsc{Demonstrator} to search for solar axions, the Ge crystal axes need to be measured. In this talk, we will present our experimental measurements to characterize crystal axes with P-type point contact (PPC) HPGe detectors, which are cylindrical in shape with point contacts at the bottom. [Preview Abstract] |
Saturday, April 13, 2013 4:54PM - 5:06PM |
D9.00008: The {\sc Majorana Demonstrator}, a $^{76}$Ge-based neutrinoless double-beta decay experiment Jacqueline Strain The observation of neutrinoless double-beta decay would confirm the Majorana nature of the neutrino, show lepton number is not conserved, and would provide a value for the effective Majorana neutrino mass. The goal of the M\textsc{ajorana} collaboration is to develop a tonne-scale $^{76}$Ge-based neutrinoless double-beta decay experiment. Currently, efforts are underway to construct the M\textsc{ajorana} D\textsc{emonstrator}, a 40-kg array of germanium crystals, located at the 4850$^{\prime}$ level of the Sanford Underground Research Facility (SURF) in Lead, SD. The goal of the D\textsc{emonstrator} is to demonstrate the ability to construct a detector composed of an array of germanium crystals while maintaining an unprecedented low background that is essential for the observation of neutrinoless double-beta decay. The past and current efforts in the construction of the D\textsc{emonstrator} and its predecessor, the Prototype Cryostat, will be presented. [Preview Abstract] |
Saturday, April 13, 2013 5:06PM - 5:18PM |
D9.00009: $2\nu\beta\beta$ of $^{96}$Zr to the First Excited $0^+$ State Sean Finch, Werner Tornow A progress report is presented on our work to measure the double-beta decay of $^{96}$Zr to the first excited $0^+$ state of $^{96}$Mo. Such measurements provide valuable test cases for $2\nu\beta\beta$ nuclear matrix element calculations, which in turn are used to tune $0\nu\beta\beta$ nuclear matrix element calculations. After undergoing double-beta decay, the excited $0^+$ state decays via the $0^+\rightarrow 2^+ \rightarrow 0^+$ decay sequence in the daughter nucleus, emitting two coincident $\gamma$ rays. These two $\gamma$ rays are detected in coincidence by two HPGe detectors sandwiching the $^{96}$Zr sample, with a NaI veto in anti-coincidence. This experimental apparatus, located at the Kimballton Underground Research Facility (KURF), has previously been used to measure the $T_{1/2}$ of $^{100}$Mo and $^{150}$Nd to the first excited $0^+$ states. The present experiment is an attempt to detect this decay mode in a third nuclide. The experiment is hindered by our small sample mass of 17.9 grams of enriched $^{96}$Zr, which has a natural abundance 2.8$\%$. Preliminary results will be shown. [Preview Abstract] |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700