Showing papers by "T. J. Sumner published in 2016"
European Space Agency1, Leibniz University of Hanover2, Paris Diderot University3, Imperial College London4, University of Rome Tor Vergata5, University of Trento6, Airbus Defence and Space7, fondazione bruno kessler8, University of Birmingham9, Institut de Ciències de l'Espai10, ETH Zurich11, UK Astronomy Technology Centre12, INAF13, University of Urbino14, European Space Operations Centre15, University of Zurich16, University of Glasgow17, Polytechnic University of Catalonia18, Goddard Space Flight Center19, University of Florence20
TL;DR: The first results of the LISA Pathfinder in-flight experiment demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density.
Abstract: We report the first results of the LISA Pathfinder in-flight experiment. The results demonstrate that two free-falling reference test masses, such as those needed for a space-based gravitational wave observatory like LISA, can be put in free fall with a relative acceleration noise with a square root of the power spectral density of 5.2 +/- 0.1 fm s(exp -2)/square root of Hz, or (0.54 +/- 0.01) x 10(exp -15) g/square root of Hz, with g the standard gravity, for frequencies between 0.7 and 20 mHz. This value is lower than the LISA Pathfinder requirement by more than a factor 5 and within a factor 1.25 of the requirement for the LISA mission, and is compatible with Brownian noise from viscous damping due to the residual gas surrounding the test masses. Above 60 mHz the acceleration noise is dominated by interferometer displacement readout noise at a level of (34.8 +/- 0.3) fm square root of Hz, about 2 orders of magnitude better than requirements. At f less than or equal to 0.5 mHz we observe a low-frequency tail that stays below 12 fm s(exp -2)/square root of Hz down to 0.1 mHz. This performance would allow for a space-based gravitational wave observatory with a sensitivity close to what was originally foreseen for LISA.
523 citations
Case Western Reserve University1, Imperial College London2, South Dakota School of Mines and Technology3, University of Maryland, College Park4, University of Edinburgh5, Yale University6, Lawrence Livermore National Laboratory7, University of California, Santa Barbara8, Brown University9, University of South Dakota10, University of California, Davis11, University of Coimbra12, Lawrence Berkeley National Laboratory13, University College London14, University of Rochester15, University of California, Berkeley16, SLAC National Accelerator Laboratory17, Texas A&M University18, State University of New York System19
TL;DR: This new analysis incorporates several advances: single-photon calibration at the scintillation wavelength, improved event-reconstruction algorithms, a revised background model including events originating on the detector walls in an enlarged fiducial volume, and new calibrations from decays of an injected tritium β source and from kinematically constrained nuclear recoils down to 1.1 keV.
Abstract: We present constraints on weakly interacting massive particles (WIMP)-nucleus scattering from the 2013 data of the Large Underground Xenon dark matter experiment, including 1.4×10^{4} kg day of search exposure. This new analysis incorporates several advances: single-photon calibration at the scintillation wavelength, improved event-reconstruction algorithms, a revised background model including events originating on the detector walls in an enlarged fiducial volume, and new calibrations from decays of an injected tritium β source and from kinematically constrained nuclear recoils down to 1.1 keV. Sensitivity, especially to low-mass WIMPs, is enhanced compared to our previous results which modeled the signal only above a 3 keV minimum energy. Under standard dark matter halo assumptions and in the mass range above 4 GeV c^{-2}, these new results give the most stringent direct limits on the spin-independent WIMP-nucleon cross section. The 90% C.L. upper limit has a minimum of 0.6 zb at 33 GeV c^{-2} WIMP mass.
460 citations
Case Western Reserve University1, Imperial College London2, South Dakota School of Mines and Technology3, University of Maryland, College Park4, University of Edinburgh5, Yale University6, Lawrence Livermore National Laboratory7, University of California, Santa Barbara8, Brown University9, University of South Dakota10, University of California, Davis11, University of Coimbra12, Lawrence Berkeley National Laboratory13, University College London14, University of Rochester15, University of California, Berkeley16, SLAC National Accelerator Laboratory17, Texas A&M University18, State University of New York System19
TL;DR: The spin-dependent WIMP-neutron limit is the most sensitive constraint to date.
Abstract: We present experimental constraints on the spin-dependent WIMP (weakly interacting massive particle)-nucleon elastic cross sections from LUX data acquired in 2013. LUX is a dual-phase xenon time projection chamber operating at the Sanford Underground Research Facility (Lead, South Dakota), which is designed to observe the recoil signature of galactic WIMPs scattering from xenon nuclei. A profile likelihood ratio analysis of 1.4×10^{4} kg day of fiducial exposure allows 90% C.L. upper limits to be set on the WIMP-neutron (WIMP-proton) cross section of σ_{n}=9.4×10^{-41} cm^{2} (σ_{p}=2.9×10^{-39} cm^{2}) at 33 GeV/c^{2}. The spin-dependent WIMP-neutron limit is the most sensitive constraint to date.
195 citations
TL;DR: In this paper, the electron-recoil (ER) response of the LUX dark matter detector based upon 170 000 highly pure and spatially uniform tritium decays is investigated.
Abstract: We present measurements of the electron-recoil (ER) response of the LUX dark matter detector based upon 170 000 highly pure and spatially uniform tritium decays. We reconstruct the tritium energy spectrum using the combined energy model and find good agreement with expectations. We report the average charge and light yields of ER events in liquid xenon at 180 and 105 V/cm and compare the results to the NEST model. We also measure the mean charge recombination fraction and its fluctuations, and we investigate the location and width of the LUX ER band. These results provide input to a reanalysis of the LUX run 3 weakly interacting massive particle search.
92 citations
Posted Content•
TL;DR: The Large Underground Xenon (LUX) experiment is a dual-phase liquid xenon time projection chamber (TPC) operating at the Sanford Underground Research Facility in Lead, South Dakota.
Abstract: The Large Underground Xenon (LUX) experiment is a dual-phase liquid xenon time projection chamber (TPC) operating at the Sanford Underground Research Facility in Lead, South Dakota. A calibration of nuclear recoils in liquid xenon was performed $\textit{in situ}$ in the LUX detector using a collimated beam of mono-energetic 2.45 MeV neutrons produced by a deuterium-deuterium (D-D) fusion source. The nuclear recoil energy from the first neutron scatter in the TPC was reconstructed using the measured scattering angle defined by double-scatter neutron events within the active xenon volume. We measured the absolute charge ($Q_{y}$) and light ($L_{y}$) yields at an average electric field of 180 V/cm for nuclear recoil energies spanning 0.7 to 74 keV and 1.1 to 74 keV, respectively. This calibration of the nuclear recoil signal yields will permit the further refinement of liquid xenon nuclear recoil signal models and, importantly for dark matter searches, clearly demonstrates measured ionization and scintillation signals in this medium at recoil energies down to $\mathcal{O}$(1 keV).
55 citations
Posted Content•
27 Aug 2016
50 citations
European Space Agency1, Leibniz University of Hanover2, Paris Diderot University3, Imperial College London4, University of Trento5, Airbus Defence and Space6, fondazione bruno kessler7, University of Birmingham8, ETH Zurich9, Institut de Ciències de l'Espai10, University of Urbino11, European Space Operations Centre12, University of Zurich13, University of Glasgow14, Polytechnic University of Catalonia15, Goddard Space Flight Center16
TL;DR: The LISA Pathfinder satellite was launched on 3 December 2015 toward the Sun Earth first Lagrangian point (L1) where the LISA Technology Package (LTP), which is the main science payload, will be tested.
Abstract: LISA Pathfinder satellite was launched on 3 December 2015 toward the Sun Earth first Lagrangian point (L1) where the LISA Technology Package (LTP), which is the main science payload, will be tested. LTP achieves measurements of differential acceleration of free-falling test masses (TMs) with sensitivity below 3 x 10(exp -14) m s(exp -2) Hz(exp - 1/2) within the 130 mHz frequency band in one dimension. The spacecraft itself is responsible for the dominant differential gravitational field acting on the two TMs. Such a force interaction could contribute a significant amount of noise and thus threaten the achievement of the targeted free-fall level. We prevented this by balancing the gravitational forces to the sub nm s(exp -2) level, guided by a protocol based on measurements of the position and the mass of all parts that constitute the satellite, via finite element calculation tool estimates. In this paper, we will introduce the gravitational balance requirements and design, and then discuss our predictions for the balance that will be achieved in flight.
19 citations
Posted Content•
10 Feb 2016
TL;DR: In this article, the spin-dependent WIMP-nucleon elastic cross sections from LUX data acquired in 2013 were used to obtain a profile likelihood ratio analysis for fiducial exposure.
Abstract: We present the first experimental constraints on the spin-dependent WIMP-nucleon elastic cross sections from LUX data acquired in 2013. LUX is a dual-phase xenon time projection chamber operating at the Sanford Underground Research Facility (Lead, South Dakota), which is designed to observe the recoil signature of galactic WIMPs scattering from xenon nuclei. A profile likelihood ratio analysis of $1.4~\times~10^{4}~\text{kg}\cdot~\text{days}$ of fiducial exposure allows 90% CL upper limits to be set on the WIMP-neutron (WIMP-proton) cross section of $\sigma_n~=~9.4~\times~10^{-41}~\text{cm}^2$ ($\sigma_p~=~2.9~\times~10^{-39}~\text{cm}^2$) at 33 GeV/c$^2$. The spin-dependent WIMP-neutron limit is the most sensitive constraint to date.
17 citations
Case Western Reserve University1, Stanford University2, SLAC National Accelerator Laboratory3, Imperial College London4, South Dakota School of Mines and Technology5, University of Maryland, College Park6, University of Edinburgh7, Yale University8, Lawrence Livermore National Laboratory9, University of California, Santa Barbara10, Brown University11, University of South Dakota12, University of California, Davis13, University of Coimbra14, Lawrence Berkeley National Laboratory15, University College London16, University of Rochester17, University of California, Berkeley18, Texas A&M University19, State University of New York System20
11 May 2016-Nuclear Instruments & Methods in Physics Research Section A-accelerators Spectrometers Detectors and Associated Equipment
TL;DR: LUX as discussed by the authors is a two-phase (liquid/gas) xenon time projection chamber designed to detect nuclear recoils resulting from interactions with dark matter particles, which is continuously and reliably operating since its full underground deployment in early 2013.
Abstract: LUX is a two-phase (liquid/gas) xenon time projection chamber designed to detect nuclear recoils resulting from interactions with dark matter particles. Signals from the detector are processed with an FPGA-based digital trigger system that analyzes the incoming data in real-time, with just a few microsecond latency. The system enables first pass selection of events of interest based on their pulse shape characteristics and 3D localization of the interactions. It has been shown to be >99% efficient in triggering on S2 signals induced by only few extracted liquid electrons. It is continuously and reliably operating since its full underground deployment in early 2013. This document is an overview of the systems capabilities, its inner workings, and its performance.
15 citations
University of California, Santa Barbara1, Case Western Reserve University2, Imperial College London3, South Dakota School of Mines and Technology4, University of Maryland, College Park5, University of Edinburgh6, Yale University7, Lawrence Livermore National Laboratory8, University of South Dakota9, Brown University10, University of Coimbra11, University of Rochester12, Lawrence Berkeley National Laboratory13, University of California, Davis14, University College London15, University of California, Berkeley16, Texas A&M University17
TL;DR: LUX (Large Underground Xenon) is a WIMP 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.
8 citations