This paper reports on the development of a technology involving 100 Mo-enriched scintillating bolometers, compatible with the goals of CUPID, a proposed nextgeneration bolometric experiment to search for neutrinoless double-beta decay. Large mass (∼ 1 kg), high optical quality, radiopure 100 Mo-containing zinc and lithium molybdate crystals have been produced and used to develop high performance single detector modules based on 0.2-0.4 kg scintillating bolometers. In particular, the energy resolution of the lithium molybdate detectors near the Q-value of the doublebeta transition of 100 Mo (3034 keV) is 4-6 keV FWHM. The rejection of the α-induced dominant background above 2.6 MeV is better than 8σ . Less than 10 µBq/kg activity of 232 Th ( 228 Th) and 226 Ra in the crystals is ensured by boule recrystallization. The potential of 100 Mo-enriched scintillating bolometers to perform high sensitivity double-beta decay searches has been demonstrated with only 10 kg×d exposure: the two neutrino double-beta decay half-life of 100 Mo has been measured with the up-to-date highest accuracy as T 1/2 = [6.90 ± 0.15(stat.) ± 0.37(syst.)] × 10 18 years. Both crystallization and detector technologies favor lithium molybdate, which has been selected for the ongoing construction of the CUPID-0/Mo demonstrator, containing several kg of 100 Mo.

they elastically scatter off nuclei [4,5]. In recent decades, significant advances have been made in the search for WIMPs in the GeV/c 2 -to TeV/c 2 -range that is natural for Supersymmetry [6][7][8]. However, in the light of the absence of signal in that region there is an increasing interest in DM particles in the GeV/c 2 and sub-GeV/c 2 mass range [9][10][11][12][13][14][15]. These searches require experimental thresholds as low as a few tens of eV, a performance that can be attained by cryogenic detectors [16,17]. A particular advantage of such detector technology is that the thermal signal is not affected by the strong quenching effects that tend to severely reduce the amplitude of ionization or scintillation signals at low energy. This paper describes the results obtained by the EDELWEISS collaboration with a 33.4-g Ge detector demonstrating that such a device equipped with a neutron-transmutation-doped Ge (Ge-NTD) sensor [18] can reach the sensitivity to probe the sub-GeV domain. As a proof of the relevance of this technology, it is used in

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CUPID-Mo is a bolometric experiment to search for neutrinoless double-beta decay (0νβ β ) of 100 Mo. In this article, we detail the CUPID-Mo detector concept, assema e-mail: andrea.giuliani@csnsm.in2p3.fr bly, installation in the underground laboratory in Modane in 2018, and provide results from the first datasets. The demonstrator consists of an array of 20 scintillating bolometers comprised of 100 Mo-enriched 0.2 kg Li 2 MoO 4 crystals. The

21 pages, 5 figuresThe EDELWEISS-II collaboration has completed a direct search for WIMP dark matter with an array of ten 400-g cryogenic germanium detectors in operation at the Laboratoire Souterrain de Modane. The combined use of thermal phonon sensors and charge collection electrodes with an interleaved geometry enables the efficient rejection of gamma-induced radioactivity as well as near-surface interactions. A total effective exposure of 384 kg.d has been achieved, mostly coming from fourteen months of continuous operation. Five nuclear recoil candidates are observed above 20 keV, while the estimated background is less than 3.0 events. The result is interpreted in terms of limits on the cross-section of spin-independent interactions of WIMPs and nucleons. A cross-section of 4.4x10^-8 pb is excluded at 90%CL for a WIMP mass of 85 GeV. New constraints are also set on models where the WIMP-nucleon scattering is inelastic

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.

We report on a search for low-energy (E < 20 keV) WIMP-induced nuclear recoils using data collected in 2009 − 2010 by EDELWEISS from four germanium detectors equipped with thermal sensors and an electrode design (ID) which allows to efficiently reject several sources of background. The data indicate no evidence for an exponential distribution of low-energy nuclear recoils that could be attributed to WIMP elastic scattering after an exposure of 113 kg·d. For WIMPs of mass 10 GeV, the observation of one event in the WIMP search region results in a 90% CL limit of 1.0 × 10 −5 pb on the spin-independent WIMP-nucleon scattering cross-section, which constrains the parameter space associated with the findings reported by the CoGeNT, DAMA and CRESST experiments.

Abstract. We present new constraints on the couplings of axions and more generic axionlike particles using data from the EDELWEISS-II experiment. The EDELWEISS experiment, located at the Underground Laboratory of Modane, primarily aims at the direct detection of WIMPs using germanium bolometers. It is also sensitive to the low-energy electron recoils that would be induced by solar or dark matter axions. Using a total exposure of up to 448 kg.d, we searched for axion-induced electron recoils down to 2.5 keV within four scenarios involving different hypotheses on the origin and couplings of axions. We set a 95 % CL limit on the coupling to photons g Aγ < 2.13 × 10 −9 GeV −1 in a mass range not fully covered by axion helioscopes. We also constrain the coupling to electrons, g Ae < 2.56 × 10 −11 , similar to the more indirect solar neutrino bound. Finally we place a limit on g Ae × g eff AN < 4.70 × 10 −17 , where g eff AN is the effective axion-nucleon coupling for 57 Fe. Combining these results we fully exclude the mass range 0.91 eV < m A < 80 keV for DFSZ axions and 5.73 eV < m A < 40 keV for KSVZ axions.