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تسجيل مستخدم جديدNew Limit for Neutrinoless Double-Beta Decay of $^{100}$Mo from the CUPID-Mo Experiment
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The CUPID-Mo experiment at the Laboratoire Souterrain de Modane (France) is a demonstrator for CUPID, the next-generation ton-scale cryogenic $0 ubetabeta$ experiment. It consists of a 4.2 kg array of 20 enriched Li$_{2}$$^{100}$MoO$_4$ scintillating bolometers to search for the lepton number violating process of $0 ubetabeta$ decay in $^{100}$Mo. With more than one year of operation (2.16 kg$times$yr of physics data), no event in the region of interest and hence no evidence for $0 ubetabeta$ is observed. We report a new limit on the half-life of $0 ubetabeta$ decay in $^{100}$Mo of $T_{1/2} > 1.5 times 10^{24},$yr at 90 % C.I. The limit corresponds to an effective Majorana neutrino mass $langle m_{betabeta} rangle$ $<$ (0.31--0.54)$,$eV, dependent on the nuclear matrix element in the light Majorana neutrino exchange interpretation.
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The CUPID-Mo experiment is searching for neutrinoless double beta decay in $^{100}$Mo, evaluating the technology of cryogenic scintillating Li$_{2}^{100}$MoO$_4$ detectors for CUPID (CUORE Upgrade with Particle ID). CUPID-Mo detectors feature backgro
und suppression using a dual-readout scheme with Li$_{2}$MoO$_4$ crystals complemented by Ge bolometers for light detection. The detection of both heat and scintillation light signals allows the efficient discrimination of $alpha$ from $gamma$&$beta$ events. In this proceedings, we discuss results from the first 2 months of data taking in spring 2019. In addition to an excellent bolometric performance of 6.7$,$keV (FWHM) at 2615$,$keV and an $alpha$ separation of better than 99.9% for all detectors, we report on bulk radiopurity for Th and U. Finally, we interpret the accumulated physics data in terms of a limit of $T_{1/2}^{0 u},> 3times10^{23},$yr for $^{100}$Mo and discuss the sensitivity of CUPID-Mo until the expected end of physics data taking in early 2020.
CUPID-Mo is a bolometric experiment to search for neutrinoless double-beta decay ($0 ubetabeta$) of $^{100}$Mo. In this article, we detail the CUPID-Mo detector concept, assembly, installation in the underground laboratory in Modane in 2018, and prov
ide 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 detectors are complemented by 20 thin cryogenic Ge bolometers acting as light detectors to distinguish $alpha$ from $gamma$/$beta$ events by the detection of both heat and scintillation light signals. We observe good detector uniformity, facilitating the operation of a large detector array as well as excellent energy resolution of 5.3 keV (6.5 keV) FWHM at 2615 keV, in calibration (physics) data. Based on the observed energy resolutions and light yields a separation of $alpha$ particles at much better than 99.9% with equally high acceptance for $gamma$/$beta$ events is expected for events in the region of interest for $^{100}$Mo $0 ubetabeta$. We present limits on the crystals radiopurity ($leq$3 $mu$Bq/kg of $^{226}$Ra and $leq$2 $mu$Bq/kg of $^{232}$Th). Based on these initial results we also discuss a sensitivity study for the science reach of the CUPID-Mo experiment, in particular, the ability to set the most stringent half-life limit on the $^{100}$Mo $0 ubetabeta$ decay after half a year of livetime. The achieved results show that CUPID-Mo is a successful demonstrator of the technology - developed in the framework of the LUMINEU project - selected for the CUPID experiment, a proposed follow-up of CUORE, the currently running first tonne-scale cryogenic $0 ubetabeta$ experiment.
Energy resolution, alpha/beta ratio, pulse-shape discrimination for gamma rays and alpha particles, temperature dependence of scintillation properties, and radioactive contamination were studied with CaMoO4 crystal scintillators. A high sensitivity e
xperiment to search for neutrinoless double beta decay of 100-Mo by using CaMoO4 scintillators is discussed.
The NEMO-3 detector, which had been operating in the Modane Underground Laboratory from 2003 to 2010, was designed to search for neutrinoless double $beta$ ($0 ubetabeta$) decay. We report final results of a search for $0 ubetabeta$ decays with $6.91
4$ kg of $^{100}$Mo using the entire NEMO-3 data set with a detector live time of $4.96$ yr, which corresponds to an exposure of 34.3 kg$cdot$yr. We perform a detailed study of the expected background in the $0 ubetabeta$ signal region and find no evidence of $0 ubetabeta$ decays in the data. The level of observed background in the $0 ubetabeta$ signal region $[2.8-3.2]$ MeV is $0.44 pm 0.13$ counts/yr/kg, and no events are observed in the interval $[3.2-10]$ MeV. We therefore derive a lower limit on the half-life of $0 ubetabeta$ decays in $^{100}$Mo of $T_{1/2}(0 ubetabeta)> 1.1 times 10^{24}$ yr at the $90%$ Confidence Level, under the hypothesis of light Majorana neutrino exchange. Depending on the model used for calculating nuclear matrix elements, the limit for the effective Majorana neutrino mass lies in the range $langle m_{ u} rangle < 0.33$--$0.62$ eV. We also report constraints on other lepton-number violating mechanisms for $0 ubetabeta$ decays.
We report the results of a search for the neutrinoless double-$beta$ decay (0$ ubetabeta$) of $^{100}$Mo, using the NEMO-3 detector to reconstruct the full topology of the final state events. With an exposure of 34.7 kg.y, no evidence for the 0$ ubet
abeta$ signal has been found, yielding a limit for the light Majorana neutrino mass mechanism of $T_{1/2}(0 ubetabeta)>1.1 times 10^{24}$ years (90% C.L.) once both statistical and systematic uncertainties are taken into account. Depending on the Nuclear Matrix Elements this corresponds to an upper limit on the Majorana effective neutrino mass of $< m_{ u} > < 0.3-0.9$ eV (90% C.L.). Constraints on other lepton number violating mechanisms of 0$ ubetabeta$ decays are also given. Searching for high-energy double electron events in all suitable sources of the detector, no event in the energy region [3.2-10] MeV is observed for an exposure of 47 kg.y.
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