Bulletin of the American Physical Society
APS April Meeting 2013
Volume 58, Number 4
Saturday–Tuesday, April 13–16, 2013; Denver, Colorado
Session D11: Dark Matter II |
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Sponsoring Units: DPF Chair: Dmitri Denisov, Fermi National Accelerator Laboratory Room: Governor's Square 17 |
Saturday, April 13, 2013 3:30PM - 3:42PM |
D11.00001: Results from a direct dark matter search with the MAJORANA low-background broad energy germanium detector Padraic Finnerty As a part of the research and development efforts for the \textsc{Majorana} experiment, we have deployed a customized Canberra broad energy germanium (BEGe) detector at the Kimballton Underground Research Facility (KURF). We have performed a direct search for low-mass particle dark matter using a 221.49 live day (89.53 kg-d) exposure. We discuss the backgrounds and report on results from this search, and their compatibility with other experiments that probe the low WIMP-mass ($<$10 GeV) parameter space. [Preview Abstract] |
Saturday, April 13, 2013 3:42PM - 3:54PM |
D11.00002: The LUX experiment - Overview and Status Blair Edwards The LUX (Large Underground Xenon) detector is designed to directly detect the elastic scattering of WIMPs (Weakly Interacting Massive Particles) on xenon nuclei. The 350 kg (100 kg fiducial) two-phase liquid xenon TPC is sensitive to both scintillation and ionization signals. The ratio of these two signals provides discrimination between potential nuclear recoil signals and electronic recoils with a rejection efficiency of at least 99.5{\%} (with 50{\%} nuclear recoil acceptance). The detector was operated on the surface at the Sanford Underground Research Facility (SURF) from November 2011 until February 2012, before being installed 4850 feet underground. This talk will lay out the motivations for the LUX experiment, provide an overview of the detector, and discuss the underground installation, xenon handling and water tank systems. [Preview Abstract] |
Saturday, April 13, 2013 3:54PM - 4:06PM |
D11.00003: The LUX Experiment - Background Model and Physics Goals David Malling The LUX experiment takes advantage of the self-shielding capabilities of liquid xenon to create a nearly background-free fiducial volume. This will allow for unambiguous detection of WIMP-like nuclear recoils. LUX has been designed with the goal of $<$10$^{-3}$~event/keV/kg/day, corresponding to $<$1~background event in 300~livedays, and a virtually background-free month-long initial science run. The ultimate 90\% exclusion WIMP limit of the experiment after a 30000~kg~day run is projected to reach 7$\times$10$^{-46}$~cm$^2$ for a WIMP mass of 100~GeV. This talk will discuss recent results from the LUX underground xenon gas run and background projections from the LUX material screening program. [Preview Abstract] |
Saturday, April 13, 2013 4:06PM - 4:18PM |
D11.00004: Operation and First Data of DM-Ice17 at the South Pole Matthew Kauer DM-Ice17 is a set of two NaI(Tl) detectors with a combined mass of 17 kg located at a depth of 2450 m in the Antarctic ice at the South Pole. In this experiment the signature for WIMP dark matter is an annual modulation in the nuclear recoil signal events. DM-Ice17 is a prototype detector for a first direct search for dark matter in the Southern Hemisphere. Seasonal effects have a reversed phase relative to the Northern Hemisphere and together provide a complimentary understanding of those systematics. Furthermore, the South Pole ice provides an extremely stable environment year around. In this talk we present data from the operation of the DM-Ice17 experiment since January 2011 and discuss the stability, performance, and expected WIMP sensitivity. [Preview Abstract] |
Saturday, April 13, 2013 4:18PM - 4:30PM |
D11.00005: Understanding and modeling the backgrounds for dark matter search at the South Pole with DM-Ice17 and DM-Ice Bethany Reilly DM-Ice17 is a NaI detector to search for annual modulation of dark matter signal. The detector was deployed in December 2010 at the geographic South Pole and has been in operation since January 2011. Geant4 is used to simulate and study the various backgrounds from materials in and surrounding the detector. I will present the comparison of the Geant4 simulation with data from DM-Ice17. I will also present the simulation of the projected backgrounds of the full-scale detector. [Preview Abstract] |
Saturday, April 13, 2013 4:30PM - 4:42PM |
D11.00006: Cosmogenic Activation in the DM-Ice Experiment Walter Pettus DM-Ice is a quarter-ton-scale dark matter experiment planned for deployment deep in the ice at the South Pole. This experiment will search for the expected annual modulation signature in the dark matter signal using low-background NaI(Tl) scintillating crystals. Cosmogenic activation of the detectors during transport to and storage at the South Pole (altitude 9,186 feet) has the potential to produce long-lived radioisotopes which will add a significant source of background and threaten the discovery potential of this experiment. We present simulation studies in the rate of activation and the spectral affect these additional radioactive decays will have. In data from the presently operating DM-Ice17 detectors, we compare the simulated activation spectra with decaying spectral regions. For the full-scale DM-Ice, we discuss the possible effects of this activation, and mitigation strategies being explored. [Preview Abstract] |
Saturday, April 13, 2013 4:42PM - 4:54PM |
D11.00007: Event Characteristics in DM-Ice-17 Zachary Pierpoint DM-Ice17, a 17 kg sodium iodide prototype detector for the proposed DM-Ice experiment, was deployed in the Antarctic Ice at the geographic South Pole in December 2010, and has been in operation since January 2011. A variety of types of events are observed in DM-Ice17 characterized by distinct waveforms and trigger conditions. Defining characteristics of these different events allow for identification, and consequently, cuts on the dataset have been developed. I will describe the types of events in our detector, their trigger efficiency, and the observed background rates in DM-Ice17. [Preview Abstract] |
Saturday, April 13, 2013 4:54PM - 5:06PM |
D11.00008: Energy Response of DM-Ice17 Antonia Hubbard Dark Matter-Ice (DM-Ice) is a South Pole dark matter experiment using NaI(Tl) detectors. It will search for the annual modulation signature expected in the WIMP-nucleon collision rate. A 17-kg prototype detector (DM-Ice17) has been in operation since January 2011 with stable data since June 2011. We present here the data analysis from DM-Ice17. It is a unique challenge to calibrate a detector buried under 2450 m of ice, and I will discuss the use of internal contamination lines for calibration and introduce the verification of calibration through comparison with simulation. [Preview Abstract] |
Saturday, April 13, 2013 5:06PM - 5:18PM |
D11.00009: Lattice calculation of composite dark matter form factors David Schaich Composite dark matter candidates, which can arise from new strongly-coupled sectors, are well-motivated and phenomenologically interesting, particularly in the context of asymmetric generation of the relic density. I will present large-scale lattice calculations of electromagnetic form factors of electroweak-neutral dark-matter ``baryons'' that arise from QCD-like SU(3) gauge theories with $N_f = 2$ and 6 degenerate fermions in the fundamental representation. This recent work of the Lattice Strong Dynamics Collaboration studies the composite dark matter charge radius and anomalous magnetic moment, both of which can play a significant role for direct detection. We find minimal $N_f$ dependence in these quantities, and generate mass-dependent cross-sections for the dark matter--nucleon interaction. In conjunction with experimental results from XENON100, we exclude dark matter candidates of this type with masses below 10~TeV. [Preview Abstract] |
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