20 research outputs found
Search for light dark matter with ionization signals in the PandaX-4T Experiment
We report the search results of light dark matter through its interactions
with shell electrons and nuclei, using the commissioning data from the
PandaX-4T liquid xenon detector. Low energy events are selected to have an
ionization-only signal between 60 to 200 photoelectrons, corresponding to a
mean nuclear recoil energy from 0.77 to 2.54 keV and electronic recoil energy
from 0.07 to 0.23 keV. With an effective exposure of 0.55 tonneyear, we
set the most stringent limits within a mass range from 40 MeV/ to 10
GeV/ for point-like dark matter-electron interaction, 100
MeV/ to 10 GeV/ for dark matter-electron interaction via a
light mediator, and 3 to 4.5 GeV/ for dark matter-nucleon
spin-independent interaction. For DM interaction with electrons, our limits are
closing in on the parameter space predicted by the freeze-in and freeze-out
mechanisms in the early Universe.Comment: 5 pages, 5 figur
Low-mass dark matter search results from full exposure of PandaX-I experiment
We report the results of a weakly-interacting massive particle (WIMP) dark
matter search using the full 80.1\;live-day exposure of the first stage of the
PandaX experiment (PandaX-I) located in the China Jin-Ping Underground
Laboratory. The PandaX-I detector has been optimized for detecting low-mass
WIMPs, achieving a photon detection efficiency of 9.6\%. With a fiducial liquid
xenon target mass of 54.0\,kg, no significant excess event were found above the
expected background. A profile likelihood analysis confirms our earlier finding
that the PandaX-I data disfavor all positive low-mass WIMP signals reported in
the literature under standard assumptions. A stringent bound on the low mass
WIMP is set at WIMP mass below 10\,GeV/c, demonstrating that liquid xenon
detectors can be competitive for low-mass WIMP searches.Comment: v3 as accepted by PRD. Minor update in the text in response to
referee comments. Separating Fig. 11(a) and (b) into Fig. 11 and Fig. 12.
Legend tweak in Fig. 9(b) and 9(c) as suggested by referee, as well as a
missing legend for CRESST-II legend in Fig. 12 (now Fig. 13). Same version as
submitted to PR
Performance of the EDELWEISS-III experiment for direct dark matter searches
We present the results of measurements demonstrating the efficiency of the EDELWEISS-III array of cryogenic germanium detectors for direct dark matter searches. The experimental setup and the FID (Fully Inter-Digitized) detector array is described, as well as the efficiency of the double measurement of heat and ionization signals in background rejection. For the whole set of 24 FID detectors used for coincidence studies, the baseline resolutions for the fiducial ionization energy are mainly below 0.7 keV (FHWM) whereas the baseline resolutions for heat energies are mainly below 1.5 keV (FWHM). The response to nuclear recoils as well as the very good discrimination capability of the FID design has been measured with an AmBe source. The surface - and -decay rejection power of per at 90% C.L. has been determined with a Pb source, the rejection of bulk -ray events has been demonstrated using -calibrations with Ba sources leading to a value of at 90% C.L.. The current levels of natural radioactivity measured in the detector array are shown as the rate of single background. The fiducial volume fraction of the FID detectors has been measured to a weighted average value of using the cosmogenic activation of the Zn and Ge isotopes. The stability and uniformity of the detector response is also discussed. The achieved resolutions, thresholds and background levels of the upgraded EDELWEISS-III detectors in their setup are thus well suited to the direct search of WIMP dark matter over a large mass range
Status and recent dark matter search results from the PandaX experiment
The PandaX project is a staged xenon-based deep underground experiment at the China Jin-Ping Underground Laboratory. The first phase experiment, PandaX-I, a 120 kg dark matter detector using the dual phase xenon time projection chamber (TPC) technology was completed in 2014 with a 5480.1 kg-day exposure. Recently, the commissioning run of the second phase of the experiment, PandaX-II, was completed with a 30619.1 kg-day exposure. We report the status of the PandaX experiment, and then present the dark matter search results from both runs