Final results on the 0νββ0νββ decay half-life limit of 100^{100}Mo from the CUPID-Mo experiment

The CUPID-Mo experiment to search for 0$\nu\beta\beta$ decay in $^{100}$Mo has been recently completed after about 1.5 years of operation at Laboratoire Souterrain de Modane (France). It served as a demonstrator for CUPID, a next generation 0$\nu\beta\beta$ decay experiment. CUPID-Mo was comprised of 20 enriched Li$_2$$^{100}$MoO$_4$ scintillating calorimeters, each with a mass of $\sim$ 0.2 kg, operated at $\sim$20 mK. We present here the final analysis with the full exposure of CUPID-Mo ($^{100}$Mo exposure of 1.47 kg$\times$yr) used to search for lepton number violation via 0$\nu\beta\beta$ decay. We report on various analysis improvements since the previous result on a subset of data, reprocessing all data with these new techniques. We observe zero events in the region of interest and set a new limit on the $^{100}$Mo 0$\nu\beta\beta$ decay half-life of T^{0\nu}_{1/2} > 1.8 \times 10^{24} year (stat.+syst.) at 90% C.I. Under the light Majorana neutrino exchange mechanism this corresponds to an effective Majorana neutrino mass of \left < (0.28--$0.49)$ eV, dependent upon the nuclear matrix element utilized

Final results on the 0 νββ decay half-life limit of 100 Mo from the CUPID-Mo experiment

The CUPID-Mo experiment to search for 0νββ decay in 100Mo has been recently completed after about 1.5&nbsp;years of operation at Laboratoire Souterrain de Modane (France). It served as a demonstrator for CUPID, a next generation 0νββ decay experiment. CUPID-Mo was comprised of 20 enriched Li 2100MoO 4 scintillating calorimeters, each with a mass of ∼ 0.2 kg, operated at ∼ 20 mK. We present here the final analysis with the full exposure of CUPID-Mo (100Mo exposure of 1.47 kg × year) used to search for lepton number violation via 0νββ decay. We report on various analysis improvements since the previous result on a subset of data, reprocessing all data with these new techniques. We observe zero events in the region of interest and set a new limit on the 100Mo 0νββ decay half-life of T1/20ν&gt; 1.8 × 10 24&nbsp;year (stat.&nbsp;+&nbsp;syst.) at 90% CI. Under the light Majorana neutrino exchange mechanism this corresponds to an effective Majorana neutrino mass of 〈 mββ〉 &lt;(0.28-0.49)&nbsp;eV, dependent upon the nuclear matrix element utilized

Precise measurement of 2 ν 2 β decay of 100Mo with Li2MoO4 low temperature detectors: Preliminary results

The half-life of 100Mo relatively to the 2ν2β decay to the ground state of 100Ru was measured as T1/2 = (6.99±0.15) × 1018 yr with the help of enriched in 100Mo lithium molybdate scintillating bolometers in the EDELWEISS-III low background set-up at the Modane underground laboratory. This is the most accurate value of the 2ν2β half-life of 100Mo

The CUPID-Mo experiment for neutrinoless double-beta decay: performance and prospects

CUPID-Mo is a bolometric experiment to search for neutrinoless double-beta decay (0 νββ) of 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 100Mo -enriched 0.2 kg Li 2MoO 4 crystals operated as scintillating bolometers at ∼20mK. The Li 2MoO 4 crystals are complemented by 20 thin Ge optical bolometers to reject 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 α particles at a level much higher than 99.9% – with equally high acceptance for γ/β events – in the region of interest for 100Mo 0 νββ. We present limits on the crystals’ radiopurity: ≤3μBq/kg of 226Ra and ≤2μBq/kg of 232Th. We discuss the science reach of CUPID-Mo, which can set the most stringent half-life limit on the 100Mo 0 νββ 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 νββ experiment

The CUPID-Mo experiment for neutrinoless double-beta decay: performance and prospects

International audienceCUPID-Mo is a bolometric experiment to search for neutrinoless double-beta decay ($0\nu \beta \beta$) of $^{100}\hbox {Mo}$. 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 $^{100}\hbox {Mo}$-enriched 0.2 kg $\hbox {Li}_2\hbox {MoO}_4$ crystals operated as scintillating bolometers at $\sim 20\hbox { mK}$. The $\hbox {Li}_2\hbox {MoO}_4$ crystals are complemented by 20 thin Ge optical bolometers to reject $\alpha$ 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 $\alpha$ particles at a level much higher than 99.9% – with equally high acceptance for $\gamma$/$\beta$ events – in the region of interest for $^{100}\hbox {Mo}0\nu \beta \beta$. We present limits on the crystals’ radiopurity: $\le 3~\mu \hbox {Bq/kg}$ of $^{226}\hbox {Ra}$ and $\le 2~\mu \hbox {Bq/kg}$ of $^{232}\hbox {Th}$. We discuss the science reach of CUPID-Mo, which can set the most stringent half-life limit on the $^{100}\hbox {Mo}0\nu \beta \beta$ 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 $0\nu \beta \beta$ experiment

Precise measurement of 2 νββ decay of 100 Mo with the CUPID-Mo detection technology

We report the measurement of the two-neutrino double-beta (2 νββ) decay of 100Mo to the ground state of 100Ru using lithium molybdate (Li2100MoO4) scintillating bolometers. The detectors were developed for the CUPID-Mo program and operated at the EDELWEISS-III low background facility in the Modane underground laboratory (France). From a total exposure of 42.235 kg× day, the half-life of 100Mo is determined to be T1/22ν=[7.12-0.14+0.18(stat.)±0.10(syst.)]×1018&nbsp;years. This is the most accurate determination of the 2 νββ half-life of 100Mo to date

Pulse shape discrimination in CUPID-Mo using principal component analysis

CUPID-Mo is a cryogenic detector array designed to search for neutrinoless double-beta decay (0νββ) of 100Mo. It uses 20 scintillating 100Mo-enriched Li2MoO4 bolometers instrumented with Ge light detectors to perform active suppression of α backgrounds, drastically reducing the expected background in the 0νββ signal region. As a result, pileup events and small detector instabilities that mimic normal signals become non-negligible potential backgrounds. These types of events can in principle be eliminated based on their signal shapes, which are different from those of regular bolometric pulses. We show that a purely data-driven principal component analysis based approach is able to filter out these anomalous events, without the aid of detector response simulations

Combined limits on WIMPs from the CDMS and EDELWEISS experiments

The CDMS and EDELWEISS collaborations have combined the results of their direct searches for dark matter using cryogenic germanium detectors. The total data set represents 614kg•days equivalent exposure. A straightforward method of combination was chosen for its simplicity before data were exchanged between experiments. The results are interpreted in terms of limits on spin-independent weakly interacting, massive particle (WIMP)-nucleon cross section. For a WIMP mass of 90GeV/c2, where this analysis is most sensitive, a cross section of 3.3×10-44cm2 is excluded at 90% C.L. At higher WIMP masses, the combination improves the individual limits, by a factor 1.6 above 700GeV/c2. Alternative methods of combining the data provide stronger constraints for some ranges of WIMP masses and weaker constraints for others. © 2011 American Physical Society