Bulletin of the American Physical Society
2008 APS April Meeting and HEDP/HEDLA Meeting
Volume 53, Number 5
Friday–Tuesday, April 11–15, 2008; St. Louis, Missouri
Session D13: Minisymposium on Nuclear Physics Deep Underground II |
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Sponsoring Units: DNP Chair: Andrew Hime, Los Alamos National Laboratory Room: Hyatt Regency St. Louis Riverfront (formerly Adam's Mark Hotel), St. Louis F |
Saturday, April 12, 2008 1:30PM - 1:42PM |
D13.00001: Measuring External Sources of Background (R\&D) at Homestake Dongming Mei, Yuen-Dat Chan, Steve Elliott, Frederick Gray, Christina Keller, Yongchen Sun Measuring external sources of radioactivity at the DUSEL site is the key to success in low-energy neutrino and dark matter (WIMP searches) experiments. Natural radioactivity can be measured using germanium and NaI detectors. Muon-induced neutrons and (a,n) neutrons will be measured utilizing liquid scintillators and germanium detectors through the 72Ge(n,nxe) reaction. External sources of background, particularly fast neutrons and cosmogenic radioactivity from muon-induced processes, are background matter that must be eliminated for underground experiments in pursuit of double beta decay, WIMPs, and oscillations of low-energy neutrinos. However, muon-induced neutron production rates with heavy elements, such as lead and copper, are not well understood. The discrepancy between the measurements and FLUKA simulations is as large as about a factor of 3. This discrepancy needs be understood for the muon- induced fast neutron production rate in lead and copper, which are the most popular materials for shielding underground experiments. We propose an experiment at 300-ft level to measure the muon-induced fast neutron production rate in different targets. [Preview Abstract] |
Saturday, April 12, 2008 1:42PM - 1:54PM |
D13.00002: A Low Background Counting Facility for the Deep Underground Science and Engineering Laboratory (DUSEL) at Homestake Y. Chan, A. Alton, C. Keller, K. Lesko, D. Mei, R. McTaggart, G. Prior, W. Roggenthen, A. Smith, Y. Sun, B. Szczerbinska, Z. Yin A versatile radioactivity-screening facility is crucial to the DUSEL program, as most of the proposed physics experiments will deal with rare-occurring processes that could be concealed by natural or induced radioactivity from the experimental devices and environment. A State of South Dakota EPSCOR proposal has been submitted to establish a counting facility in the Homestake mine, at the 4,800 ft u.g. level, as part of the early implementation program (SUSEL, Sanford Laboratory). The facility will have dedicated stations for ultra-low level gamma counting, as well as general purpose and high throughput screening stations. The facility will also couple to other underground science initiatives such as underground manufacturing, clean material selection and stockpile etc. The detector resources can be utilized for certain physics measurements as well. [Preview Abstract] |
Saturday, April 12, 2008 1:54PM - 2:06PM |
D13.00003: A Muon Veto Shielded Cavern for Underground Experiments and Shower Studies Nathaniel Pastika, Priscilla Cushman The Low Background Counting Facility at the Soudan Underground Lab includes a 33' x 42' x 100' experimental hall lined with proportional tubes from a former proton decay experiment. These tubes have been refubished and equipped with a modern data acquisition system which records the location and time-stamp of every muon which enters the room. The programmable logic allows a user to run in a customized trigger/veto mode or using offline hit registration. This large-area muon detector has also been used to study the muon angular distribution and resulting cosmogenic hadronic showers at 2100 mwe. [Preview Abstract] |
Saturday, April 12, 2008 2:06PM - 2:18PM |
D13.00004: TUNL activities at the Kimballton Underground Research Facility Henning Olling Back, Arthur Champagne, Reyco Henning, Padraic Finnerty, Werner Tornow, Mary Kidd, James Esterline The Triangle Universities Nuclear Laboratory (TUNL) has taken a large role in the nuclear physics research performed underground at the Kimballton Underground Research Facility operated by Virginia Tech near its campus. Currently two TUNL efforts are underway at Kimballton: 1) double-beta decay/double electron capture experiments to excited final states, which employ high purity germanium detectors to search for signature gammas from the decay of the excited final state and 2) a material assay program that will determine radioactive contamination in detector materials through gamma ray spectroscopy. In this talk I will present the current status of the Kimballton Underground Research Facility and the TUNL activities located there. [Preview Abstract] |
Saturday, April 12, 2008 2:18PM - 2:30PM |
D13.00005: Systematic study of cosmogenic activation with low background Ge spectroscopy at the Kimballton Underground Research Facility Padraic Finnerty, Henning Back, Reyco Henning A systematic study of the activation rate of materials due to cosmic rays with the aid of low background Ge spectroscopy is proposed. The next generation of underground physics experiments will require unprecedented control and characterization of the intrinsic radioactive isotopes in their detection mediums and construction materials. One such source is the activation of materials via cosmic ray interactions in the upper atmosphere. We propose to activate materials at high altitude, $\sim $14,000 feet above sea level, by utilizing storage space made available to us by the University of Denver's Meyer-Womble Observatory. Low background Ge spectroscopy will then be performed at the Kimballton Underground Research Facility (KURF), located near the campus of Virginia Tech, to determine the cosmogenic isotope production rates. [Preview Abstract] |
Saturday, April 12, 2008 2:30PM - 2:42PM |
D13.00006: Neutron-induced backgrounds in Cu and Ge D.V. Perepelitsa, V.E. Guiseppe, S.R. Elliott, R.O. Nelson, N. Fotiades, M. Devlin, R.C. Haight, D.-M. Mei, Z. Yin Measurements of ($n,n'\gamma$) reactions in Cu and Ge are important for understanding neutron-induced background for some underground double beta decay experiments. Neutron-induced gammas are a contribution to background for the next generation of double beta decay experiments, which are designed to reach the sensitivity of the atmospheric neutrino mass scale (45 meV). Measuring and understanding the high-energy neutron excitations of the shielding and detector materials for neutrinoless double beta decay experiments are crucial for interpreting results and establishing shielding requirements. Locating some specific excited state transitions in various materials represents a significant nuclear structure contribution. Partial $\gamma$-ray cross sections were measured using the GEANIE spectrometer surrounding Cu and Ge (enriched in $^{76}$Ge) targets in a broad-spectrum neutron beam at LANSCE. The cross sections provide useful data for benchmarking Monte Carlo simulation of background events. [Preview Abstract] |
Saturday, April 12, 2008 2:42PM - 2:54PM |
D13.00007: Neutron-Induced Partial Cross Section Measurements on Cu, Ge and Pb at E$_n$ = 8 and 12 MeV for Background Radiation in $\mathbf{0\nu\beta\beta}$ Decay Experiments E. Kwan, J.H. Esterline, B. Fallin, C.R. Howell, A. Hutcheson, M.F. Kidd, A. Tonchev, W. Tornow, C. Angell, H. Karwowski, J. Kelley, D. Mei, S. Hilderbrand, D.B. Masters, R.S. Pedroni, G.J. Weisel The search for the existence of 0$\nu\beta\beta$ decay plays an important role in the uncovering of physics beyond the standard model. The detection of such decay would confirm that neutrinos are Majorana particles. The large lifetimes (\textit{i.e.},T$_{1/2}$($^{76}$Ge) $>$ 10$^{25}$ y) and the corresponding long measuring times require extensive understanding of background radiation induced by neutron interactions with shielding and detector materials. For example, neutron induced $\gamma$-ray transitions in Pb and Cu and their escape peaks could interfere with the identification of the 2039 keV signature of 0$\nu\beta\beta$ in the case of $^ {76}$Ge. Thus, it is necessary to determine the yields from possible background sources. The neutron-induced partial cross sections for $\gamma$-ray transitions in Cu, enriched $^{76} $Ge, and Pb were measured at TUNL using an array of HPGe detectors at E$_n$=8 and 12 MeV. The experimental setup and preliminary results will be presented.\\ Supported by DOE Grants DE-FG02-97ER41033 \& DE- FG02-97ER41042.\\ [Preview Abstract] |
Saturday, April 12, 2008 2:54PM - 3:06PM |
D13.00008: High-energy neutron counting deep underground Raul Hennings-Yeomans, Daniel Akerib, Michael Dragowsky, Matthew Harrison, Harry Nelson Dark matter is concentrated in the halos of galaxies, including the Milky Way. If WIMPs make up these halos they can be detected via scattering from atomic nuclei in a terrestrial detector. Experiments that search for WIMPs are one of the critical science drivers for a Deep Underground Science and Engineering Laboratory in the United States. Nuclear recoils from fast neutrons in underground laboratories are one of the most challenging backgrounds to WIMP detection and are estimated using Monte Carlo simulations. We present the design of an instrument capable of benchmarking the Monte Carlos by measuring the high energy $>$60~MeV muon-induced neutron flux deep underground. The instrument is based on applying Gd-loaded liquids to measure the rate of multiple low-energy neutron events produced in a Pb target and from this measurement to infer the rate of high energy neutron events. We will present design studies of the instrument as well as the current status and prospects for the construction and deployment of the instrument at the deep site. [Preview Abstract] |
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