Performance of the EDELWEISS-III experiment for direct dark matter searches

Abstract

A : 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 βand α-decay rejection power of R surf < 4 × 10 −5 per α at 90% C.L. has been determined with a 210 Pb source, the rejection of bulk γ-ray events has been demonstrated using γ-calibrations with 133 Ba sources leading to a value of R γ−mis−fid < 2.5 × 10 −6 at 90% C.L.. The current levels of natural radioactivity measured in the detector array are shown as the rate of single γ background. The fiducial volume fraction of the FID detectors has been measured to a weighted average value of (74.6 ± 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.

Low-Noise HEMTs for Coherent Elastic Neutrino Scattering and Low-Mass Dark Matter Cryogenic Semiconductor Detectors

“…The current noise dominates the resolution for the 100 pF HEMT while is negligible for the 5 pF HEMT. Our model predicts an remarkable 19 eV ee rms ionization baseline resolution for the 5 pF HEMT which is one order of magnitude better than the best resolution achieved on ionisation with cryogenic detectors [1,27].…”

“…Two schemes are thus being investigating : 1) a simple follower HEMT-based stage at 1-4 K, very close to the detector with a very low noise 300 K stage and 2) an hybrid HEMT + SiGe / MOS ASICs high gain stage at 1-4K. The follower scheme is used by the EDELWEISS collaboration [1,26] and works are in progress to adapt it to an HEMT input. A production of ASICs based on the 0.35 µm SiGe biCMOS technology from AMS foundry has been delivered and will be tested soon.…”

“…Electrostatic simulations ( Fig. 6) show that the EDELWEISS Fully Inter-Digitized (FID) 800g detector [1] ionization electrode pattern can be adapted to match the 20 pF capacitance requirement with a ∼30 g detector. This FID detector geometry has been shown to efficiently reject surface events, which may be advantageous for CEνNS and low-mass WIMP searches where the low energy backgrounds are unknown.…”

“…This allows for an excellent event-by-event discrimination between nuclear and electron recoils. Discrimination power better than 10 6 have been demonstrated by both the CDMS and EDELWEISS [1] collaborations for recoil energies above ∼ 10 keV.…”

First data from the CUPID-Mo neutrinoless double beta decay experiment

“…The detectors modules are arranged into 5 towers of 4 modules, where each module comprises a Li 2 100 MoO 4 crystal at the top and an adjacent thin Ge light detector below. This detector arrangement is housed inside of the low radioactivity infrastructure of the EDELWEISS-III experiment [14,15] in the underground laboratory of Modane (France). The setup and the detector performance were characterized in an initial commissioning campaign in March 2019 and have been described in detail in [12].…”