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.
We present constraints on weakly interacting massive particles (WIMP)-nucleus scattering from the 2013 data of the Large Underground Xenon dark matter experiment, including $1.4times10^{4};mathrm{kg; day}$ 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 $beta$ 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 $mathrm{GeV},c^{-2}$, 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 $mathrm{GeV},c^{-2}$ WIMP mass.
We report the first results of a light weakly interacting massive particles (WIMPs) search from the CDEX-10 experiment with a 10 kg germanium detector array immersed in liquid nitrogen at the China Jinping Underground Laboratory with a physics data size of 102.8 kg day. At an analysis threshold of 160 eVee, improved limits of 8 $times 10^{-42}$ and 3 $times 10^{-36}$ cm$^{2}$ at a 90% confidence level on spin-independent and spin-dependent WIMP-nucleon cross sections, respectively, at a WIMP mass ($m_{chi}$) of 5 GeV/${c}^2$ are achieved. The lower reach of $m_{chi}$ is extended to 2 GeV/${c}^2$.
New constraints are presented on the spin-dependent WIMP-nucleon interaction from the PandaX-II experiment, using a data set corresponding to a total exposure of 3.3$times10^4$ kg-days. Assuming a standard axial-vector spin-dependent WIMP interaction with $^{129}$Xe and $^{131}$Xe nuclei, the most stringent upper limits on WIMP-neutron cross sections for WIMPs with masses above 10 GeV/c$^{2}$ are set in all dark matter direct detection experiments. The minimum upper limit of $4.1times 10^{-41}$ cm$^2$ at 90% confidence level is obtained for a WIMP mass of 40 GeV/c$^{2}$. This represents more than a factor of two improvement on the best available limits at this and higher masses. These improved cross-section limits provide more stringent constraints on the effective WIMP-proton and WIMP-neutron couplings.
We report results on the searches of weakly interacting massive particles (WIMPs) with sub-GeV masses ($m_{chi}$) via WIMP-nucleus spin-independent scattering with Migdal effect incorporated. Analysis on time-integrated (TI) and annual modulation (AM) effects on CDEX-1B data are performed, with 737.1 kg$cdot$day exposure and 160 eVee threshold for TI analysis, and 1107.5 kg$cdot$day exposure and 250 eVee threshold for AM analysis. The sensitive windows in $m_{chi}$ are expanded by an order of magnitude to lower DM masses with Migdal effect incorporated. New limits on $sigma_{chi N}^{rm SI}$ at 90% confidence level are derived as $2times$10$^{-32}sim7times$10$^{-35}$ $rm cm^2$ for TI analysis at $m_{chi}sim$ 50$-$180 MeV/$c^2$, and $3times$10$^{-32}sim9times$10$^{-38}$ $rm cm^2$ for AM analysis at $m_{chi}sim$75 MeV/$c^2-$3.0 GeV/$c^2$.
We present the results of the three-month above-ground commissioning run of the Large Underground Xenon (LUX) experiment at the Sanford Underground Research Facility located in Lead, South Dakota, USA. LUX is a 370 kg liquid xenon detector that will search for cold dark matter in the form of Weakly Interacting Massive Particles (WIMPs). The commissioning run, conducted with the detector immersed in a water tank, validated the integration of the various sub-systems in preparation of the underground deployment. Using the data collected, we report excellent light collection properties, achieving 8.4 photoelectrons per keV for 662 keV electron recoils without an applied electric field, measured in the center of the WIMP target. We also find good energy and position resolution in relatively high-energy interactions from a variety of internal and external sources. Finally, we have used the commissioning data to tune the optical properties of our simulation and report updated sensitivity projections for spin-independent WIMP-nucleon scattering.
LUX Collaboration: D. S. Akerib
,H. M. Araujo
,X. Bai
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(2016)
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"Results on the Spin-Dependent Scattering of Weakly Interacting Massive Particles on Nucleons from the Run 3 Data of the LUX Experiment"
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Adam Bailey
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