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Register a new userFirst germanium-based constraints on sub-MeV Dark Matter with the EDELWEISS experiment
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The EDELWEISS collaboration has performed a search for Dark Matter (DM) particles interacting with electrons using a 33.4 g Ge cryogenic detector operated underground at the LSM. A charge resolution of 0.53 electron-hole pairs (RMS) has been achieved using the Neganov-Trofimov-Luke amplification with a bias of 78 V. We set the first Ge-based constraints on sub-MeV/c$^{2}$ DM particles interacting with electrons, as well as on dark photons down to 1 eV/c$^2$. These are competitive with other searches. In particular, new limits are set on the kinetic mixing of dark photon DM in a so far unconstrained parameter space region in the 6 to 9 eV/c$^2$ mass range. These results demonstrate the high relevance of cryogenic Ge detectors for the search of DM interactions producing eV-scale electron signals.
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We present the results of a search for elastic scattering from galactic dark matter in the form of Weakly Interacting Massive Particles (WIMPs) in the 4-30 GeV/$c^2$ mass range. We make use of a 582 kg-day fiducial exposure from an array of 800 g Germanium bolometers equipped with a set of interleaved electrodes with full surface coverage. We searched specifically for $sim 2.5-20$ keV nuclear recoils inside the detector fiducial volume. As an illustration the number of observed events in the search for 5 (resp. 20) GeV/$c^2$ WIMPs are 9 (resp. 4), compared to an expected background of 6.1 (resp. 1.4). A 90% CL limit of $4.3times 10^{-40}$ cm$^2$ (resp. $9.4times 10^{-44}$ cm$^2$) is set on the spin-independent WIMP-nucleon scattering cross-section for 5 (resp. 20) GeV/$c^2$ WIMPs. This result represents a 41-fold improvement with respect to the previous EDELWEISS-II low-mass WIMP search for 7 GeV/$c^2$ WIMPs. The derived constraint is in tension with hints of WIMP signals from some recent experiments, thus confirming results obtained with different detection techniques.
We report on the first dark-matter (DM) search results from PandaX-I, a low threshold dual-phase xenon experiment operating at the China Jinping Underground Laboratory. In the 37-kg liquid xenon target with 17.4 live-days of exposure, no DM particle candidate event was found. This result sets a stringent limit for low-mass DM particles and disfavors the interpretation of previously-reported positive experimental results. The minimum upper limit, $3.7times10^{-44}$,cm$^2$, for the spin-independent isoscalar DM-particle-nucleon scattering cross section is obtained at a DM-particle mass of 49,GeV/c$^2$ at 90% confidence level.
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$_{ee}$ (FHWM) whereas the baseline resolutions for heat energies are mainly below 1.5 keV$_{ee}$ (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 $beta$- and $alpha$-decay rejection power of $R_{rm surf} < 4 times 10^{-5}$ per $alpha$ at 90% C.L. has been determined with a $^{210}$Pb source, the rejection of bulk $gamma$-ray events has been demonstrated using $gamma$-calibrations with $^{133}$Ba sources leading to a value of $R_{gamma{rm -mis-fid}} < 2.5 times 10^{-6}$ at 90% C.L.. The current levels of natural radioactivity measured in the detector array are shown as the rate of single $gamma$ background. The fiducial volume fraction of the FID detectors has been measured to a weighted average value of $(74.6 pm 0.4)%$ using the cosmogenic activation of the $^{65}$Zn and $^{68,71}$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.
ANAIS is a direct detection dark matter experiment aiming at the testing of the DAMA/LIBRA annual modulation result, which standing for about two decades has neither been confirmed nor ruled out by any other experiment in a model independent way. ANAIS-112, consisting of 112.5 kg of sodium iodide crystals, is taking data at the Canfranc Underground Laboratory, Spain, since August 2017. This letter presents the annual modulation analysis of 1.5 years of data, amounting to 157.55 kg$times$y. We focus on the model independent analysis searching for modulation and the validation of our sensitivity prospects. ANAIS-112 data are consistent with the null hypothesis (p-values of 0.65 and 0.16 for [2-6] and [1-6] keV energy regions, respectively). The best fits for the modulation hypothesis are consistent with the absence of modulation ($S_m$=-0.0044$pm$0.0058 cpd/kg/keV and -0.0015$pm$0.0063 cpd/kg/keV, respectively). They are in agreement with our estimated sensitivity for the accumulated exposure, supporting our projected goal of reaching a 3$sigma$ sensitivity to the DAMA/LIBRA result in 5 years of data taking.
We report results from searches of pseudoscalar and vector bosonic super-weakly interacting massive particles (super-WIMP) in the TEXONO experiment at the Kuo-Sheng Nuclear Power Station, using 314.15 kg days of data from $n$-type Point-Contact Germanium detector. The super-WIMPs are absorbed and deposit total energy in the detector, such that the experimental signatures are spectral peaks corresponding to the super-WIMP mass. Measured data are compatible with the background model, and no significant excess of super-WIMP signals are observed. We derived new upper limits on couplings of electrons with the pseudoscalar and vector bosonic super-WIMPs in the sub-keV mass region, assuming they are the dominant contributions to the dark matter density of our galaxy.
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