Bulletin of the American Physical Society
APS April Meeting 2013
Volume 58, Number 4
Saturday–Tuesday, April 13–16, 2013; Denver, Colorado
Session C11: Dark Matter I |
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Sponsoring Units: DPF Chair: Bob Bernstein, Fermi National Accelerator Laboratory Room: Governor's Square 17 |
Saturday, April 13, 2013 1:30PM - 1:42PM |
C11.00001: SuperCDMS - Status and Plans Joel Sander Understanding the nature of the dark matter, which constitutes 80 percent of the matter in the Universe, remains one of the most compelling questions in physics. SuperCDMS is a program to detect dark matter particles directly through scattering off nuclei in cryogenic germanium detectors. I will describe the SuperCDMS technology, and discuss current and planned projects. SuperCDMS-Soudan, a 10-kg array in the Soudan underground laboratory, has been operating for over a year. I will give an early look at the results and the ultimate sensitivity of SuperCDMS-Soudan. SuperCDMS-SNOLAB is a 200-kg array planned for the SNOLAB facility. I will describe the projected schedule and sensitivity of SuperCDMS-SNOLAB. [Preview Abstract] |
Saturday, April 13, 2013 1:42PM - 1:54PM |
C11.00002: Full Reach of CDMS-II Ge Data Thomas Hofer The CDMS-II experiment was a dark matter direct-detection experiment using cryogenic ($\sim$50 mK) Si and Ge detector technologies. The original 2009 publication of results from the 2007-08 Ge data indicated 2 candidate events during a raw exposure of 612 kg-days. Since then, the raw data have been reprocessed with a post-unblinding modification to the pulse reconstruction algorithm, which improves timing for energies near threshold. I will present several analyses utilizing a full reprocessing of the CDMS-II 10 keV threshold Ge data. These include a ``standard'' CDMS analysis procedure in addition to procedures involving advanced nuclear-recoil / surface event discrimination and a likelihood approach. These analyses yield better expected sensitivities than the 2009 analysis, mostly due to improved analysis efficiencies from the improved charge reconstruction. [Preview Abstract] |
Saturday, April 13, 2013 1:54PM - 2:06PM |
C11.00003: Dark Matter Search Results from the Silicon Detectors of the Cryogenic Dark Matter Search Experiment Kevin McCarthy Weakly Interacting Massive Particles (WIMPs) are a class of new particles hypothesized to be components of the dark matter content of the universe. We report new results from the final data set of the Cryogenic Dark Matter Search experiment (CDMSII), an experiment designed to detect the elastic scattering of WIMPs off of Ge or Si detectors. Eleven silicon particle detectors, each with a mass of $\sim$106 grams, were deployed in the final runs of the CDMSII experiment for a total WIMP exposure of 132.39 kg-days after data quality cuts. We will present the results of a blind WIMP search analysis of this Si exposure. [Preview Abstract] |
Saturday, April 13, 2013 2:06PM - 2:18PM |
C11.00004: Low Threshold Modulation Searches in CDMS-II Danielle Speller The Cryogenic Dark Matter Search experiment (CDMS-II) uses ground-based germanium and silicon detectors to search for the scattering of Weakly Interacting Massive Particles (WIMPs), which are among the leading candidates for the dark matter component of the universe. Using the ionization and athermal phonons measured in particle interactions, CDMS-II is able to achieve excellent discrimination between the nuclear recoils expected for WIMP interactions and radioactively produced electron recoils. With the rise of interest in the low energy interactions of light mass WIMPs, CDMS-II has undertaken a search for an annually modulating signal at low thresholds. Previous results detailed the analysis of data from eight germanium detectors over the course of six runs, to thresholds of 5 keVnr (nuclear recoil energy). We will discuss an extension of this analysis to 2.27 keVnr and the implications for other WIMP search experiments. [Preview Abstract] |
Saturday, April 13, 2013 2:18PM - 2:30PM |
C11.00005: Towards a Low Threshold SuperCDMS Experiment Bradford Welliver Astrophysical evidence points to the existence of particle dark matter that comprises the majority of the mass of the universe. A natural candidate for these particles are Weakly Interacting Massive Particles, or WIMPs. Lately there has been much interest in dark matter search experiments for low mass WIMPs. Detection of WIMP dark matter with mass below 20 $GeV/c^2$ requires a low-energy trigger threshold. However, lowering the trigger threshold also makes us sensitive to triggering on random noise which can hamper livetime. In order to minimize triggering on this random noise the original trigger filters for SuperCDMS were replaced with improved filters that reduce the amplitude of random noise substantially compared to an event-generated signal, thus allowing us to lower the trigger thresholds without the livetime penalty we would otherwise accrue. An overview of how this was accomplished as well as post-triggering methods of noise discrimination will be discussed. Predictions for the improved low thresholds will be compared to data, and the impact on a low mass WIMP search will be described. [Preview Abstract] |
Saturday, April 13, 2013 2:30PM - 2:42PM |
C11.00006: The CDMSlite Experiment Ritoban Basu Thakur The SuperCDMS experiment will use new iZIP detectors to achieve competitive sensitivity in the direct detection of Dark Matter, particularly in the 100 to 1000 GeV/c$^{2}$ range of WIMP (Weakly Interacting Massive Particles) mass. In the SuperCDMS framework we are also attempting a novel low-threshold experiment to look for light WIMPs of mass O(10GeV/c$^{2})$. We call this the CDMS low ionization threshold experiment or ''CDMSlite.'' Here, we use high bias voltage to amplify the charge signal from low-energy recoils by increasing their Luke phonon emission. In this manner we reduce the detector threshold. I will describe the physics behind CDMSlite and comment on our expected sensitivity to low-mass WIMPs. I will also discuss our progress from running CDMSlite. [Preview Abstract] |
Saturday, April 13, 2013 2:42PM - 2:54PM |
C11.00007: Results from the XENON1T Demonstrator Hugo Contreras, Elena Aprile, Ranny Budnik, Luke Goetzke, Guillaume Plante, Marcello Messina, Alfio Rizzo, Antonio Melgarejo, Junji Naganoma, Petr Chaguine The current stage of the XENON Dark Matter Search project, XENON100, constitutes one of the best performing dark matter experiments in the world, setting the best upper limit on the cross section for spin independent WIMP-nucleus scattering. The next generation detector within the program, XENON1T, is at the end of its design phase and construction will start in the present year. XENON1T is a liquid xenon dual-phase time projection chamber with a 1 Ton fiducial mass, and it will improve the present XENON100 limit by 2 orders of magnitude. However, the increase in mass in the new detector presents several technological challenges. In order to address the required improvements, a fully operational prototype of the detector, the XENON1T Demonstrator, has been built at Columbia University. In this talk we will present the main results of the XENON1T Demonstrator R\&D program, comprising high-speed recirculation on a full-scale cryogenic system, the observation of electron drift over 30 cm, and the operation of the detector with a cathode high voltage exceeding 30kV and preliminary results of the new 60 and 100 cm setups. [Preview Abstract] |
Saturday, April 13, 2013 2:54PM - 3:06PM |
C11.00008: Updates from the DMTPC Dark Matter Search Jeremy Lopez The motion of Earth through the galactic dark matter halo combined with the rotation of Earth around its axis is expected to create a large daily modulation in the typical directions of WIMP dark matter induced nuclear recoils. This modulation, if found, would provide strong evidence for WIMP interactions with normal matter. To search for this signal, the Dark Matter Time Projection Chamber (DMTPC) collaboration is developing gas TPCs that can measure the directions of low energy nuclear recoils in low pressure CF$_4$ gas. DMTPC detectors use a mesh-based amplification region to measure the ionization profiles of recoils on a two-dimensional readout plane. CCD cameras are used to achieve sub-millimeter spatial resolution for a typical nuclear recoil range of one to several millimeters. This talk will discuss the commissioning and calibration of a prototype DMTPC detector in a surface laboratory at MIT. This detector, the 4-shooter, is testing several new features necessary for a planned 1~m$^3$ fiducial volume detector currently being designed. Upon completion of surface calibrations in early 2013, the 4-shooter detector will be installed underground at the Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico. [Preview Abstract] |
Saturday, April 13, 2013 3:06PM - 3:18PM |
C11.00009: The DRIFT Directional Dark Matter Detector Eric Miller The DRIFT dark matter detector is a 1 cubic meter scale TPC with directional sensitivity to WIMP recoils operating in the Boulby Mine in England. The directional sensitivity allows DRIFT to detect the sidereal modulation of the WIMP recoils and provide an unambiguous confirmation of a dark matter interaction. We present current limits from DRIFT and provide a brief update on background reduction efforts. [Preview Abstract] |
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