Bulletin of the American Physical Society
2011 Fall Meeting of the APS Division of Nuclear Physics
Volume 56, Number 12
Wednesday–Saturday, October 26–29, 2011; East Lansing, Michigan
Session JG: Astrophysics V: Dark Matter and Unification |
Hide Abstracts |
Chair: Dong Ming Mei, University of South Dakota Room: 105AB |
Friday, October 28, 2011 2:00PM - 2:12PM |
JG.00001: Argon Depletion for a Large Scale Dark Matter Detector Dana Byram, Dongming Mei, Dustin Nowotny, Jason Spaans A system of Thermal Diffusion columns is being built and tested at the University of South Dakota for the purposes of providing argon depleted of $^{39}$Ar. Thermal diffusion is a well-known technique in isotope separation, which introduces a radial temperature gradient in a gas column to produce a vertical concentration gradient via convective currents. In this concentration gradient, the heavier isotopes accumulate at the bottom of the column and the lighter isotopes at the top. The test system under development will allow us to deplete 1 kg of natural argon by a factor of 10 for over two months. This would lead to the full-scale production of depleted argon by using more columns that are longer in length. In addition, recycling depleted argon through the column yields further depletion up to a theoretical maximum factor of about 1000. This highly depleted argon could then be used as a target material for next generation dark matter detectors. Preliminary depletion results in 3 meter columns will be reported utilizing the more abundant isotope $^{36}$Ar and progress toward an automated gas collection system will be discussed. [Preview Abstract] |
Friday, October 28, 2011 2:12PM - 2:24PM |
JG.00002: The MiniCLEAN Dark Matter Experiment Richard Schnee The MiniCLEAN dark matter experiment exploits a single-phase liquid argon (LAr) detector, instrumented with photomultiplier tubes submerged in the cryogen with nearly $4\pi$ coverage of a 500 kg target (150 kg fiducial) mass. The high light yield and large difference in singlet/triplet scintillation time-profiles in LAr provide effective defense against radioactive backgrounds through pulse-shape discrimination and event position reconstruction. The detector is also designed for a liquid neon target which, in the event of a positive signal in LAr, will enable an independent verification of backgrounds and provide a unique test of the expected $A^2$ dependence of the WIMP interaction rate. The conceptually simple design can be scaled to target masses in excess of 10 tons in a relatively straightforward and economic manner. The experimental technique and current status of MiniCLEAN will be summarized. [Preview Abstract] |
Friday, October 28, 2011 2:24PM - 2:36PM |
JG.00003: Photomultiplier tube characterization for MiniCLEAN Stephen Jaditz MiniCLEAN is a single-phase dark matter experiment which uses liquid argon (87 K) or neon (27 K) as an active medium. Photomultiplier tubes (PMTs) submerged in the cryogen detect light emitted by tetraphenyl butadiene, which fluoresces at short optical wavelengths when excited by the primary ultraviolet scintillation of the argon or neon. The collaboration has chosen to use 8'' Hamamatsu R5912-02MOD PMTs, the low-temperature successor of the R1408-R5912 lineage. The bialkali photocathode of the R5912-02MOD has a platinum underlay which increases electron mobility, enabling operation at temperatures lower than 150 K where traditional bialkali cathodes fail. The number of dynodes in the tube has also been increased to 14, which lowers the bias required to attain reasonable gain and saves heat load in the voltage divider chain of the base. This talk describes characterization of the tube and base for use in MiniCLEAN. I present gain and dark rate measurements as a function of temperature, considerations that inform the base design, and implications of using this tube in a low-background experiment. [Preview Abstract] |
Friday, October 28, 2011 2:36PM - 2:48PM |
JG.00004: Simulation and Analysis for the MiniCLEAN Dark Matter Experiment Stanley Seibert The MiniCLEAN dark matter experiment is an ultra-low background liquid argon and neon detector at SNOLAB with a fiducial volume of 150 kg. The ability of the experiment to exchange the target material gives MiniCLEAN both competitive sensitivity to WIMP dark matter and also the opportunity to demonstrate the technologies required to build the multi-ton detectors necessary for dark matter and precision measurements of low energy solar neutrinos. I will discuss the current status of the MiniCLEAN simulation and analysis package, called RAT. RAT is a GEANT4-based full optical simulation, which includes a complete model of the data acquisition system in order to mimic the real detector data stream for development of event-level analysis algorithms. In addition, I will report on projected performance of position reconstruction in RAT and improved timing-based techniques for particle identification. [Preview Abstract] |
Friday, October 28, 2011 2:48PM - 3:00PM |
JG.00005: C4: Prospects for an expanded search for light-mass WIMPS John Orrell, Juan Collar, Nicole Fields, Erin Fuller, Todd Hossbach, Marek Kos, Cory Overman, Doug Reid, Brent Van Devender The CoGeNT experiment located at the Soudan Underground Laboratory has reported an excess of events below an electron scattering equivalent of 1 keV. This result may be interpreted alternatively as either an unidentified background contribution or a signature of light-mass (5-10 GeV/c2) weakly interacting massive particle (WIMP) dark matter. The initial CoGeNT results were produced using a single 440 gram high-purity germanium radiation detector operated at liquid nitrogen temperature. To further test these unexpected results, an expanded CoGeNT-4 experimental design is under development. The shield design concept is presented and the science impact of a four-detector experiment is explored. Of particular interest is the sensitivity to a hypothesis for light-mass WIMP dark matter particles in the 5-10 GeV/c2 mass range that could potentially explain the initial CoGeNT results as well as the results of the DAMA/LIBRA experiment. [Preview Abstract] |
Friday, October 28, 2011 3:00PM - 3:12PM |
JG.00006: Considerations Concerning the Overall Unification Shantilal Goradia The direction of the century old search, based on non- probabilistic gravity, for the unification of forces blockades the search for consciousness at a fundamental level. Probabilistic gravity deriving strong coupling from a quantum mechanically modified inverse square law of gravity, and derivation of the fine structure constant's 137 by a computational route throw light on the quantum source of consciousness as explained in the book by this author (Quantum Consciousness - The Road to Reality) containing more details. Spooky action is a natural consequence of non local probabilistic gravity. I will show how this constitutes a play on the shoulders of the giants. [Preview Abstract] |
Friday, October 28, 2011 3:12PM - 3:24PM |
JG.00007: ABSTRACT WITHDRAWN |
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