Dark matter search intensifies as detection sensitivity improves "by more than a factor of 20"

12/15/2015 - 17:17

Glenn Roberts Jr

Photo by Matthew Kapust/Sanford Underground Research Facility

The Large Underground Xenon (LUX) dark matter experiment, which operates nearly a mile underground at the Sanford Underground Research Facility (SURF) in the Black Hills of South Dakota, has already proven itself to be the most sensitive detector in the hunt for dark matter, the unseen stuff believed to account for most of the matter in the universe. Now, a new set of calibration techniques employed by LUX scientists has again dramatically improved the detector’s sensitivity.

Researchers with LUX are looking for WIMPs, or weakly interacting massive particles, which are among the leading candidates for dark matter.


Ref: Improved WIMP scattering limits from the LUX experiment. Physical Review Letters (11 December 2015) | arXiv.org/abs/1512.03506 (PDF)


We present constraints on WIMP-nucleus scattering from the 2013 data of the Large Underground Xenon (LUX) dark matter experiment, including 1.4×104kg⋅days 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 GeVc−2, these new results give the most stringent direct limits on the spin-independent WIMP-nucleon cross section. The 90% CL upper limit has a minimum of 0.4 zb at 33 GeVc,sup>−2 WIMP mass.