Bulletin of the American Physical Society
APS April Meeting 2015
Volume 60, Number 4
Saturday–Tuesday, April 11–14, 2015; Baltimore, Maryland
Session K16: Dark Matter V |
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Sponsoring Units: DPF DNP Chair: Nathanial Craig, University of California, Santa Barbara Room: Key 12 |
Sunday, April 12, 2015 1:30PM - 1:42PM |
K16.00001: Development of the LUX detector's CH$_{3}$T calibration source and ER response Richard Knoche 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 development and deployment of an internal tritium calibration source for use in the LUX dark matter experiment. This source allows us to characterize the electron recoil band, which is the dominant population of background events, throughout the bulk of the LUX detector. It is also useful in determining important detector characteristics such as the fiducial volume and the detector threshold. After calibration is complete we remove the long lived radioisotope from our detector using the results of our R{\&}D efforts. [Preview Abstract] |
Sunday, April 12, 2015 1:42PM - 1:54PM |
K16.00002: The XENON1T Cryogenic System Yun Zhang The XENON1T experiment, currently under construction at the Laboratori Nazionali del Gran Sasso in Italy, aims at detecting dark matter weakly interacting massive particles using a dual-phase (liquid/gas) xenon time projection chamber filled with 3300kg of liquid xenon. The cryogenic system of the experiment maintains the liquid xenon target at a stable temperature and allows high speed continuous xenon purification through the use of efficient heat exchangers. The reliability of the system is achieved with two redundant pulse tube refrigerators and an additional backup liquid nitrogen cooling system. In this talk we will describe the XENON1T cryogenic system and present results from commissioning performance tests. [Preview Abstract] |
Sunday, April 12, 2015 1:54PM - 2:06PM |
K16.00003: Monitoring xenon purity in the LUX detector with a mass spectrometry system Jon Balajthy 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. To monitor for radioactive impurities such as krypton and impurities which limit charge yield such as oxygen, LUX uses a xenon sampling system consisting of a mass spectrometer and a liquid nitrogen cold trap. The cold trap separates the gaseous impurities from a small sample of xenon and allows them to pass to the mass spectrometer for analysis. We report here on results from the LUX xenon sampling program. We also report on methods to enhance the sensitivity of the cold trap technique in preparation for the next-generation LUX-ZEPLIN experiment which will have even more stringent purity requirements. [Preview Abstract] |
Sunday, April 12, 2015 2:06PM - 2:18PM |
K16.00004: Measurement of ER Fluctuations in Liquid Xenon with the LUX Detector Using a Tritium Calibration Source Attila Dobi The LUX WIMP search limit was aided by an internal tritium source resulting in an unprecedented calibration and understanding of the electronic recoil background. The source allows for a check of energy scale calibration and the extraction of fundamental properties of electron recoils in liquid xenon. Recombination probability and its fluctuation have been measured from 1 to 1000 keV, using betas from tritium and Compton scatters from an external $^{137}$Cs source. [Preview Abstract] |
Sunday, April 12, 2015 2:18PM - 2:30PM |
K16.00005: Ultra-low Energy Calibration of LUX detector using 127Xe Electron Capture Dongqing Huang 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. We present an absolute calibration of the liquid xenon electron recoil (ER) charge yield and fluctuations over an energy range 190 eVee to 33.2 keVee using low energy $^{127}$Xe electron capture decay events from the LUX 85-day first WIMP search dataset. The sequence of gamma and X-ray cascade associated with $^{127}$I produce clearly identified 2-vertex events in the LUX detector. We observe the K (33.2 keVee), L (5.2 keVee), M (1.1 keVee), and N (190 eVee) shell cascade events and verifiy the relative ratio of observed events for each shell. We extract both the mean and sigma of the charge signal yields (Q$_{y}$) associated with the K, L, M, and N shell events. The N shell cascade analysis includes single extracted electron events, and represents the lowest energy ER in-situ measurements that have been explored in Xe. [Preview Abstract] |
Sunday, April 12, 2015 2:30PM - 2:42PM |
K16.00006: A Novel Nuclear Recoil Calibration in the LUX Detector Using a D-D Neutron Generator James Verbus 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 describe a novel calibration of nuclear recoils (NR) in liquid xenon (LXe) performed in-situ in the LUX detector using mono-energetic 2.45 MeV neutrons produced by a D-D neutron generator. This technique was used to measure the NR charge yield in LXe (Q$_{y}$) to $<$1 keV recoil energy with an absolute determination of the deposited energy. The LUX Q$_{y}$ result is a factor of $\times5$ lower in energy compared to any other previous measurement in the field, and provides a significant improvement in calibration uncertainties. We also present a measurement of the NR light yield in LXe ($\mathcal{L}_{eff}$) to recoil energies as low as $\sim$2 keV using the LUX D-D data. The $\mathcal{L}_{eff}$ result is also lower in energy with smaller uncertainties than has been previously achieved. These absolute, ultra-low energy calibrations of the NR signal yields in LXe are a clear confirmation of the detector response used for the first LUX WIMP search analysis. Strategies for extending this calibration technique to even lower energies and smaller uncertainties will be discussed. [Preview Abstract] |
Sunday, April 12, 2015 2:42PM - 2:54PM |
K16.00007: Measurement of the Charge and Light Yield of Low Energy Electronic and Nuclear Recoils in Liquid Xenon at Different Electric Fields Matthew Anthony, Elena Aprile, Hugo Contreras, Luke Goetzke, Antonio Melgarejo, Guillaume Plante, Marc Weber Liquid xenon detectors continue to lead in the search for the direct detection of dark matter. Still, very few measurements have studied the response of liquid xenon to low-energy interactions ($\leq 10$ keV) at different applied electric fields. The neriX detector at Columbia University is a dual-phase time projection chamber that is optimized for simultaneous measurements of light and charge from these low-energy interactions. Coincidence techniques are employed to extract the light and charge yields from electronic and nuclear recoils in liquid xenon as a function of energy deposited and applied electric field. In this talk, we will discuss the results of the charge and light yield measurements. [Preview Abstract] |
Sunday, April 12, 2015 2:54PM - 3:06PM |
K16.00008: Background Model Status and Improvements for the LUX Detector Brian Tennyson 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. Gamma radiation from detector components produces a significant number of the background events seen by the LUX detector. The gamma ray background model implemented in an ongoing re-analysis of the first science run builds on the model employed in the original results announcement. This revised background model was created with a greater number of simulated events and allows for the model to include a spatial distribution component in addition to an energy distribution component. This revised model is expected to provide improved sensitivity to a dark matter signal in a forthcoming re-analysis, since dark matter event distribution is not expected to vary with position. [Preview Abstract] |
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