Bulletin of the American Physical Society
APS April Meeting 2016
Volume 61, Number 6
Saturday–Tuesday, April 16–19, 2016; Salt Lake City, Utah
Session B16: Liquid Xenon Dark Matter I |
Hide Abstracts |
Sponsoring Units: DPF Chair: Joseph Lykken, Fermilab Room: 251D |
Saturday, April 16, 2016 10:45AM - 10:57AM |
B16.00001: New results from the LUX Dark Matter experiment Carmen Carmona-Benitez LUX (Large Underground Xenon) is a dark matter direct detection experiment deployed at the 4850' level of the Sanford Underground Research Facility (SURF) in Lead, SD, operating a 370 kg dual-phase xenon TPC. LUX has already proved itself to be the most sensitive dark matter detector in the world. Now, we report the results of a new analysis of the data collected during LUX's first three-month run in 2013, dramatically improving our sensitivity in the low WIMP-mass range. The new analysis lowers the analysis threshold for dark matter search thanks to two new calibrations: an injected tritium $\beta$ source, and a neutron generator providing tagged nuclear recoils down to $1.1\,\mathrm{keV}$. It also includes advances on the single-photon calibration, event-reconstruction algorithms and background modeling in an enlarged fiducial volume. This new analysis gives the most stringent limits on the spin-independent WIMP-nucleon cross section in the mass range above $4\,\mathrm{GeV}\,c^{-2}$, with a minimum of $0.4\,\mathrm{zb}$ at $33\,\mathrm{GeV}\,c^{-2}$ WIMP mass. This talk will provide an overview of the experiment, focusing on the recent science results. [Preview Abstract] |
Saturday, April 16, 2016 10:57AM - 11:09AM |
B16.00002: Measurement of Yields and Fluctuations using Background and Calibration Data from the LUX Detector Evan Pease The Large Underground Xenon (LUX) detector is a 350-kg liquid xenon (LXe) time-projection chamber designed for the direct detection of weakly-interacting massive particles (WIMPs), a leading dark matter candidate. LUX operates on the 4850-foot level of the Sanford Underground Research Facility in Lead, SD. Monoenergetic electronic recoil (ER) peaks in the WIMP search and calibration data from the first underground science run of the LUX detector have been used to measure ER light and charge yields in LXe between 5.2 keV and 662 keV. The energy resolution of the LUX detector at these energies will also be presented. Recombination fluctuations are observed to follow a linear dependence on the number of ions for the energies in this study, and this dependence is consistent with low-energy measurements made with a tritium beta source in the LUX detector. Using these results and additional measurements of the recoil bands from tritium and D-D neutron calibrations, I will compare recombination fluctuations in LXe response to electronic and nuclear recoils. [Preview Abstract] |
Saturday, April 16, 2016 11:09AM - 11:21AM |
B16.00003: Modeling electric fields inside the LUX detector in 3D using $\mathrm{^{83m}Kr}$ calibration data Lucie Tvrznikova The Large Underground Xenon (LUX) experiment is a 350 kg two-phase liquid/gas xenon time projection chamber designed for the direct detection of weakly interacting massive particles, a leading dark matter candidate. LUX operates on the 4850 ft level of the Sanford Underground Research Facility in Lead, SD. Weekly calibrations using a homogeneous injection of a monoenergetic $\mathrm{^{83m}Kr}$ source enable us to monitor xenon within the active region. For this project, a 3D model of the electric fields inside the LUX detector was created using COMSOL Multiphysics software. A simulation of electrons drifting in the detector then produces a set of computational predictions. These are then reconciled with the $\mathrm{^{83m}Kr}$ data to confirm the accuracy of the field model. The result of this work is a more accurate understanding of the electric field inside the active region. This model, in conjuction with these methods, may now be used to study other phenomena such as possible surface charge buildup in detector materials. [Preview Abstract] |
Saturday, April 16, 2016 11:21AM - 11:33AM |
B16.00004: ABSTRACT WITHDRAWN |
Saturday, April 16, 2016 11:33AM - 11:45AM |
B16.00005: An investigation of the background electron emissions in the LUX detector. Jingke Xu Dual phase noble liquid detectors have demonstrated exceptional capability towards rare event detection. However, the ultimate sensitivity of such detectors at very low energies is limited by the emission of delayed ionization electrons and of uncorrelated spontaneous background electrons, generated by a variety of physical mechanisms, and originating from both the bulk liquid and detector surfaces. Using the LUX detector as an example, I will present an investigation of the different electron emission phenomena in Xe TPCs at different time scales since previous energy depositions in the detector, and attempt to identify the sources of these electrons. I will also discuss the relevance of this study for noble liquid physics and for the characterization of Xe TPC detectors. [Preview Abstract] |
Saturday, April 16, 2016 11:45AM - 11:57AM |
B16.00006: Nuclear Recoil Calibrations in the LUX Detector Using Direct and Backscattered D-D Neutrons Casey Rhyne The LUX dark matter search experiment is a 350 kg two-phase liquid/gas xenon time projection chamber located at the 4850 ft level of the Sanford Underground Research Facility in Lead, SD. I will discuss the latest calibration of the nuclear recoil (NR) response in liquid xenon (LXe), performed in-situ in the LUX detector using mono-energetic 2.45 MeV neutrons produced via the Adelphi Technologies, Inc. DD108 D-D neutron generator. The calibration measured the NR charge yield in LXe ($Q_{y}$) to 0.7 keVnr recoil energy with an absolute determination of deposited energy and the NR light yield in LXe ($L_{y}$) to recoil energies of 1.1 keVnr, both of which improve upon all previous measurements. I will then focus in depth on the extension of this calibration using a new technique for generating a beam of sub-300 keV quasi-mono-energetic neutrons via the backscatter of 2.45 MeV neutrons off a deuterium-based reflector. Current simulations work optimizing the technique, its advantages, and its impact on future research will be discussed, including the extension of the NR $Q_{y}$ calibration down to 0.14 keVnr, an independent NR $L_{y}$ calibration, and an a priori estimate of the expected $^{8}$B solar neutrino-nucleus coherent scattering signal in the upcoming LUX-ZEPLIN experiment. [Preview Abstract] |
Saturday, April 16, 2016 11:57AM - 12:09PM |
B16.00007: Absolute Electron Extraction Efficiency of Liquid Xenon Katayun Kamdin, Eli Mizrachi, James Morad, Peter Sorensen Dual phase liquid/gas xenon time projection chambers (TPCs) currently set the world’s most sensitive limits on weakly interacting massive particles (WIMPs), a favored dark matter candidate. These detectors rely on extracting electrons from liquid xenon into gaseous xenon, where they produce proportional scintillation. The proportional scintillation from the extracted electrons serves to internally amplify the WIMP signal; even a single extracted electron is detectable. Credible dark matter searches can proceed with electron extraction efficiency (EEE) lower than 100\%. However, electrons systematically left at the liquid/gas boundary are a concern. Possible effects include spontaneous single or multi-electron proportional scintillation signals in the gas, or charging of the liquid/gas interface or detector materials. Understanding EEE is consequently a serious concern for this class of rare event search detectors. Previous EEE measurements have mostly been relative, not absolute, assuming efficiency plateaus at 100\%. I will present an absolute EEE measurement with a small liquid/gas xenon TPC test bed located at Lawrence Berkeley National Laboratory. [Preview Abstract] |
Saturday, April 16, 2016 12:09PM - 12:21PM |
B16.00008: The uncertainty analysis on energy scale due to the variation of W value for liquid xenon dark matter detector Lu Wang, Dongming Mei The average energy expended per electron-ion pair, W value, is critical in understanding a liquid xenon detector energy response to low energy recoils. The reduction of scintillation and ionization yield for electronic recoils and nuclear recoils are explained using the scintillation quenching mechanism due to the variation of the average energy expended per electron hole pair, W value, which includes the energy lost to scintillation and phonon generation. We show the theoretical calculation of scintillation efficiency with W value in comparison with experimental data. The impact of variation of W value on the analysis of energy scale is discussed in detail. We conclude that the W value determined with experimental data depends on recoil energy and particle type. [Preview Abstract] |
Saturday, April 16, 2016 12:21PM - 12:33PM |
B16.00009: Average Energy Expended Per Electron-Hole Pair in Germanium Detector for Dark Matter Searches Wenzhao Wei, Lu Wang, Dongming Mei The value of $\varepsilon $, the average energy expended per electron-hole pair, plays a critical role in determining the energy threshold of a bolometer detector with germanium in dark matter searches. We propose an independent method to estimate the value of $\varepsilon $ down to milli-Kelvin range, which is the operating temperature for a SuperCDMS-like detector. A theoretical model and experimental analysis algorithm are developed in this work to estimate the value of $\varepsilon $ based on the relationship between $\varepsilon $, detector energy resolution (Fano factor) and the primary phonon energy. We also investigated the energy threshold for a SuperCDMS-like detector with the value of $\varepsilon $ calculated from our model. In this work, we present our theoretical calculation and show how to use experimental data to evaluate the value of $\varepsilon $. Subsequently, we report the temperature dependence of $\varepsilon $ and its value at 50 milli-Kelvin. This work is supported by NSF in part by the NSF OIA 1434142, DOE grant DE-FG02-10ER46709, and the State of South Dakota. [Preview Abstract] |
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