Bulletin of the American Physical Society
2008 Annual Meeting of the Division of Nuclear Physics
Volume 53, Number 12
Thursday–Sunday, October 23–26, 2008; Oakland, California
Session MC: Neutrino Physics: Instrumentation II |
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Chair: Kevin Lesko, Lawrence Berkeley National Laboratory Room: Jewet Ballroom A-B |
Sunday, October 26, 2008 10:30AM - 10:42AM |
MC.00001: Production of Neutron Transmutation Doped (NTD) Germanium Thermistors for CUORE Reina Maruyama CUORE is a cryogenic bolometer experiment designed to look for neutrinoless double beta decay in tellurium-130 in the inverted mass hierarchy region. The source/detector will consist of 988 TeO$_2$ crystals weighing a total of 740 kg, or 204 kg of Te-130. Each bolometer consists of a 5x5x5 cm$^3$ TeO$_2$ crystal, a silicon resistive heater, and a thermistor which measures the small temperature rise in the crystal when energy from a nuclear decay or background events is deposited. To achieve the required uniformity and concentration in the gallium and arsenic dopants in the thermistors, germanium wafers are neutron-transmutation doped by irradiation at a nuclear reactor. We will present the techniques developed to dope and test four 58 g high-purity germanium wafers with a diameter of 65 mm and thickness 3 mm to an absolute precision of 1\%. [Preview Abstract] |
Sunday, October 26, 2008 10:42AM - 10:54AM |
MC.00002: A Low-Temperature Energy Calibration System for the CUORE Bolometric Double Beta-Decay Experiment Karsten Heeger CUORE, the Cryogenic Underground Observatory for Rare Events, is a next-generation experiment to search for neutrinoless double beta-decay in $^{130}$Te. Using an array of 988 TeO$_{2}$ crystals at 10~mK with a total mass of $^{130}$Te of 204~kg, CUORE will search for an excess of events above background near the Q-value of 2530~keV and probe the effective neutrino mass with a sensitivity of a few tens of meV. A precise measurement of the event energy with the bolometer array is crucial for the identification of candidate double beta-decay events. A novel, low-temperature calibration system with ultra-low background is being developed to perform a precise calibration of the energy response of each of the 988 TeO$_{2}$ crystals in the CUORE bolometer array. We present the design, expected performance, and experimental challenges of this low-temperature calibration system. [Preview Abstract] |
Sunday, October 26, 2008 10:54AM - 11:06AM |
MC.00003: Barium tagging R\&D for the EXO double beta decay experiment Carter Hall The EXO collaboration is developing and executing large scale experiments to search for the neutrinoless double beta decay of Xenon-136. This decay, if observed, would have far reaching implications for neutrino physics, including the identification of the neutrino as a Majorana particle. One attractive feature of Xenon-136 as a double beta decay source is the possibility that the daughter nucleus produced by the decay (Barium-136) could be identified on an event-by-event basis through its unique spectroscopic signature. The technology to observe single barium ions in an ion trap was first developed by atomic physicists in the 1970's and 1980's. We will describe in this talk the current status of our efforts to apply this technique to address one of the most important problems in nuclear and particle physics today. [Preview Abstract] |
Sunday, October 26, 2008 11:06AM - 11:18AM |
MC.00004: The Daya Bay Calibration System: Key to $\theta_{13}$ Jianglai Liu $\theta_{13}$, the only presently unknown neutrino mixing angle, can be measured via the disappearance of electron anti-neutrinos from nuclear reactors. Using this approach, the Daya Bay experiment aims to measure $\theta_{13}$ with an unprecedented sensitivity of $\sin^2(2\theta_{13})<0.01$. To reach the desired sensitivity, the detector properties need to be understood thoroughly, and a comprehensive calibration program is a must. In this talk, I will present the calibration system that is currently under construction, and discuss important detector-related systematics that can be controlled/reduced by the calibration program. I will tie these back into the sensitivity to $\theta_{13}$ at the end of the talk. [Preview Abstract] |
Sunday, October 26, 2008 11:18AM - 11:30AM |
MC.00005: Design and Simulation of the Daya Bay Antineutrino Detectors Wei Wang The Daya Bay reactor neutrino experiment is designed to measure $\sin^2 2\theta_{13}$ to $<$ 0.01 by measuring the flux of reactor antineutrinos in detectors at near and far distances from the nuclear power plant. The experiment will use eight identical liquid scintillator detectors with 20-ton target mass installed at two near sites and one far site. A key concept of the experiment is the relative measurement of the reactor antineutrino flux between identical detectors. With known techniques the uncorrelated relative uncertainty of the antineutrino detectors can be controlled to within $\sim $0.38{\%}. Ongoing R{\&}D may further reduce the uncorrelated uncertainty down to $\sim$0.18{\%}. In this talk we will describe the detector simulations that are used to optimize the design of the 3-zone liquid scintillator antineutrino detectors and to evaluate their systematic uncertainties. Methods for the control of the Daya Bay detector systematics are described. [Preview Abstract] |
Sunday, October 26, 2008 11:30AM - 11:42AM |
MC.00006: Measurements of Liquid Scintillator and Water Properties for Daya Bay Detectors Johnny Goett The performance of water Cerenkov and scintillation detectors have a critical dependence upon the attenuation of light in the visible and near UV region of the electromagnetic spectrum (370-600 nm). New data has been obtained with a high precision apparatus constructed from simple materials. We will present measurements of the optical properties of liquid water and metal loaded liquid scintillators, with a focus on research and design for forthcoming neutrino experiments. The usefulness of this data will be demonstrated in the design of the Daya Bay experiments muon-veto and antineutrino detectors. [Preview Abstract] |
Sunday, October 26, 2008 11:42AM - 11:54AM |
MC.00007: The PMT testing system for the Daya Bay Experiment Wenqin Xu The Daya Bay Experiment is a neutrino-oscillation experiment designed to measure the mixing angle $\theta_{13}$. The goal of this experiment is a measurement of $\sin^22\theta_{13}$ to a precision of $0.01$ or better. There are 2304 $8''$ Photomultiplier tubes (PMT) for detecting the inverse-beta decay signals from the antineutrinos and for tagging the cosmic muon events. To insure that the PMTs satisfy the requirements of the experiment, a comprehensive PMT testing system has been designed and developed in UCLA. The design considerations, implementation and performance of the system will be discussed. [Preview Abstract] |
Sunday, October 26, 2008 11:54AM - 12:06PM |
MC.00008: Muon Veto System and Expected Backgrounds at DayaBay Hongshan Zhang To reach the goal of the sensitivity of $\theta_{13}$ $<$0.01 in the DayaBay experiment, we need to reduce various backgrounds to a very low level. DayaBay implements two tagging systems to detect cosmic ray induced background: 2.5 meter thick two-section water shield and RPCs. They combine to contribute a overall muon efficiency exceeding 99.5\% with an uncertainty$<$0.25\%. The muon system can also provide a spatial resolution $\sim$50cm to help distinguish fast neutron background generated from muon interactions. This talk introduces the DayaBay muon system and gives an estimate of possible background rates at DayaBay. [Preview Abstract] |
Sunday, October 26, 2008 12:06PM - 12:18PM |
MC.00009: Muon Tracking for Optimized Background Rejection at KamLAND Thomas O'Donnell KamLAND has demonstrated convincingly that neutrinos oscillate. The experiment has determined the neutrino oscillation parameter $\Delta m^{2}_{21}$ to unprecedented precision, has helped constrain the neutrino mixing angle $\theta _{12}$ and has explored the potential application of neutrinos as a geophysical probe. The heart of the detector is 1 kton of hydrocarbon based scintillator located underground in Japan. A purification upgrade is currently underway which will enable KamLAND to execute a low energy solar neutrino program in parallel with the anti-neutrino program. Like many underground experiments, fast neutrons and other spallation products from cosmic ray muons present challenging backgrounds. In many cases these backgrounds can be reduced by rejecting events with the correct spatial and temporal correlation to muons. High muon tracking resolution is desirable to achieve efficient background rejection while maintaining maximal detector exposure. A new auxiliary muon tracking system is being commissioned to optimize the main detector muon reconstruction algorithm and further characterize post muon events at KamLAND. This system and the impact for CNO/pep solar neutrino observation will be described. [Preview Abstract] |
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