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