We report new results from the search for neutrinoless double-beta decay in ${}^{130}\hspace{0.17em}\mathrm{Te}$ with the CUORE detector. This search benefits from a fourfold increase in exposure, lower trigger thresholds, and analysis improvements relative to our previous results. We observe a background of $(1.38\pm 0.07)\times {10}^{-2}\mathrm{counts}/(\mathrm{keV}\mathrm{kg}\mathrm{yr})$) in the $0\nu \beta \beta$ decay region of interest and, with a total exposure of 372.5 kg yr, we attain a median exclusion sensitivity of $1.7\times {10}^{25}\mathrm{yr}$. We find no evidence for $0\nu \beta \beta$ decay and set a 90% credibility interval Bayesian lower limit of $3.2\times {10}^{25}\mathrm{yr}$ on the ${}^{130}\hspace{0.17em}\mathrm{Te}$ half-life for this process. In the hypothesis that $0\nu \beta \beta$ decay is mediated by light Majorana neutrinos, this results in an upper limit on the effective Majorana mass of 75–350 meV, depending on the nuclear matrix elements used.

This paper reports on the development of a technology involving $$^{100}\hbox

CUPID-Mo is a bolometric experiment to search for neutrinoless double-beta decay ( $$0\nu \beta \beta $$0νββ ) of $$^{100}\hbox {Mo}$$100Mo . In this article, we detail the CUPID-Mo detector concept, assembly and installation in the Modane underground laboratory, providing results from the first datasets. The CUPID-Mo detector consists of an array of 20 $$^{100}\hbox {Mo}$$100Mo -enriched 0.2 kg $$\hbox {Li}_2\hbox {MoO}_4$$Li2MoO4 crystals operated as scintillating bolometers at $$\sim 20\hbox { mK}$$∼20mK . The $$\hbox {Li}_2\hbox {MoO}_4$$Li2MoO4 crystals are complemented by 20 thin Ge optical bolometers to reject $$\alpha $$α events by the simultaneous detection of heat and scintillation light. We observe a good detector uniformity and an excellent energy resolution of 5.3 keV (6.5 keV) FWHM at 2615 keV, in calibration (physics) data. Light collection ensures the rejection of $$\alpha $$α particles at a level much higher than 99.9% – with equally high acceptance for $$\gamma $$γ / $$\beta $$β events – in the region of interest for $$^{100}\hbox {Mo}$$100Mo $$0\nu \beta \beta $$0νββ . We present limits on the crystals’ radiopurity: $$\le 3~\mu \hbox {Bq/kg}$$≤3μBq/kg of $$^{226}\hbox {Ra}$$226Ra and $$\le 2~\mu \hbox {Bq/kg}$$≤2μBq/kg of $$^{232}\hbox {Th}$$232Th . We discuss the science reach of CUPID-Mo, which can set the most stringent half-life limit on the $$^{100}\hbox {Mo}$$100Mo $$0\nu \beta \beta $$0νββ decay in half-a-year’s livetime. The achieved results show that CUPID-Mo is a successful demonstrator of the technology developed by the LUMINEU project and subsequently selected for the CUPID experiment, a proposed follow-up of CUORE, the currently running first tonne-scale bolometric $$0\nu \beta \beta $$0νββ experiment.

We report the result of the search for neutrinoless double beta decay of ${}^{82}\mathrm{Se}$ obtained with CUPID-0, the first large array of scintillating $\mathrm{Zn}{}^{82}\mathrm{Se}$ cryogenic calorimeters implementing particle identification. We observe no signal in a 1.83 kg yr ${}^{82}\mathrm{Se}$ exposure, and we set the most stringent lower limit on the $0\nu \beta \beta$ ${}^{82}\mathrm{Se}$ half-life $T_{1/2}^{0\nu }>2.4\times {10}^{24}\mathrm{yr}$ (90% credible interval), which corresponds to an effective Majorana neutrino mass $m_{\beta \beta }<(376–770)\mathrm{meV}$ depending on the nuclear matrix element calculations. The heat-light readout provides a powerful tool for the rejection of $\alpha$ particles and allows us to suppress the background in the region of interest down to $({3.6}_{-1.4}^{+1.9})\times {10}^{-3}\mathrm{counts}/(\mathrm{keV}\mathrm{kg}\mathrm{yr})$, an unprecedented level for this technique.

The R&D project COSINUS (Cryogenic Observatory for SIgnatures seen in Next-generation Underground Searches) aims to develop a cryogenic scintillating calorimeter using an undoped NaI-crystal as...

CUPID-0 is the first pilot experiment of CUPID, a next-generation project for the measurement of neutrinoless double beta decay ($0\nu \mathrm{DBD}$) with scintillating bolometers. The detector, consisting of 24 enriched and 2 natural ZnSe crystals, has been taking data at Laboratori Nazionali del Gran Sasso from June 2017 to December 2018, collecting a ${}^{82}\mathrm{Se}$ exposure of $5.29\mathrm{kg}\times \mathrm{yr}$. In this Letter we present the phase-I results in the search for $0\nu \mathrm{DBD}$. We demonstrate that the technology implemented by CUPID-0 allows us to reach the lowest background for calorimetric experiments: $({3.5}_{-0.9}^{+1.0})\times {10}^{-3}\mathrm{counts}/(\mathrm{keV}\mathrm{kg}\mathrm{yr})$. Monitoring $3.88\times {10}^{25}$ ${}^{82}\mathrm{Se}$ $\mathrm{nuclei}\times \mathrm{yr}$ we reach a 90% credible interval median sensitivity of $T_{1/2}^{0\nu }>5.0\times {10}^{24}\mathrm{yr}$ and set the most stringent limit on the half-life of ${}^{82}\mathrm{Se}$ $0\nu \mathrm{DBD}$: $T_{1/2}^{0\nu }>3.5\times {10}^{24}\mathrm{yr}$ (90% credible interval), corresponding to ${\mathrm{m}}_{\beta \beta }<(311–638)\mathrm{meV}$ depending on the nuclear matrix element calculations.