We report the measurement of the two-neutrino double-beta (
2
ν
β
β
) decay of
100
Mo to the ground state of
100
Ru using lithium molybdate (
Li
2
100
MoO
4
) 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
100
Mo is determined to be
T
1
/
2
2
ν
=
7
.
12
-
0.14
+
0.18
(
stat
.
)
±
0.10
(
syst
.
)
×
10
18
years. This is the most accurate determination of the
2
ν
β
β
half-life of
100
Mo to date.
Abstract
In the past few years, attention has been drawn to the fact that a precision analysis of two-neutrino double beta decay (2
υββ
) allows the study of interesting physics cases like the ...emission of Majoron bosons and possible Lorentz symmetry violation. These processes modify the summed-energy distribution of the two electrons emitted in 2
υββ
. CUPID is a next-generation experiment aiming to exploit
100
Mo-enriched scintillating Li
2
MoO
4
crystals, operating as cryogenic calorimeters. Given the relatively fast half-life of
100
Mo 2
υββ
and the large exposure that can be reached by CUPID, we expect to measure with very high precision the
100
Mo 2
υββ
spectrum shape, reaching great sensitivities in the search for distortions induced by the physics beyond the Standard Model. In this contribution, we present the CUPID exclusion sensitivity for such New Physics processes, as well as the preliminary projected background of CUPID.
EDELWEISS-III is a direct dark matter search experiment, running 800 g heat-and-ionization cryogenic germanium detectors equipped with Full InterDigitized electrodes (FID) for the rejection of ...near-surface events. We report a preliminary analysis for a subset of the data (35 kg
·
days) as well as future prospects for low-mass WIMPs seach.
The EDELWEISS-II Collaboration has performed a direct search for WIMP dark matter with an array of ten 400 g heat-and-ionization cryogenic detectors equipped with interleaved electrodes for the ...rejection of near-surface events. Six months of continuous operation at the Laboratoire Souterrain de Modane have been achieved. The observation of one nuclear recoil candidate above 20 keV in an effective exposure of 144 kg d is interpreted in terms of limits on the cross-section of spin-independent interactions of WIMPs and nucleons. A cross-section of 1.0×10−7 pb is excluded at 90% CL for a WIMP mass of 80 GeV/c2. This result demonstrates for the first time the very high background rejection capabilities of these simple and robust detectors in an actual WIMP search experiment.
The EDELWEISS experiment is dedicated to the Weakly Interacting Massive Particle (WIMPs) direct search using very sensitive heat-and-ionization Germanium cryogenic detectors in a low background ...environment. The second stage of the experiment, EDELWEISS-II is designed with the aim to improve the sensitivity of EDELWEISS-I by two orders of magnitude. Results of the 2006–2007 commissioning runs and physics program for the near future are presented.
Abstract This paper reports on the development of a technology involving $$^{100}\hbox {Mo}$$ 100 Mo -enriched scintillating bolometers, compatible with the goals of CUPID, a proposed next-generation ...bolometric experiment to search for neutrinoless double-beta decay. Large mass ( $$\sim 1~\hbox {kg}$$ ∼ 1 kg ), high optical quality, radiopure $$^{100}\hbox {Mo}$$ 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 double-beta transition of $$^{100}\hbox {Mo}$$ 100 Mo (3034 keV) is 4–6 keV FWHM. The rejection of the $$\alpha $$ α -induced dominant background above 2.6 MeV is better than $$8\sigma $$ 8 σ . Less than $$10~\upmu \hbox {Bq/kg}$$ 10 μ Bq/kg activity of $$^{232}\hbox {Th}\, (^{228}\hbox {Th})$$ 232 Th ( 228 Th ) and $$^{226}\hbox {Ra}$$ 226 Ra in the crystals is ensured by boule recrystallization. The potential of $$^{100}\hbox {Mo}$$ 100 Mo -enriched scintillating bolometers to perform high sensitivity double-beta decay searches has been demonstrated with only $$10~\hbox {kg}\times \hbox {d}$$ 10 kg × d exposure: the two neutrino double-beta decay half-life of $$^{100}\hbox {Mo}$$ 100 Mo has been measured with the up-to-date highest accuracy as $$T_{1/2}$$ T 1 / 2 = 6.90 ± 0.15(stat.) ± 0.37(syst.) $$\times ~10^{18}~\hbox {years}$$ × 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 $$^{100}\hbox {Mo}$$ 100 Mo .
The EDELWEISS experiment has improved its sensitivity for the direct search for WIMP dark matter. In the recoil energy range relevant for WIMP masses below 10 TeV/
c
2, no nuclear recoils were ...observed in the fiducial volume of a heat-and-ionization cryogenic Ge detector operated in the low-background environment of the Laboratoire Souterrain de Modane in the Fréjus Tunnel, during an effective exposure of 7.4 kg
d. This result is combined with the previous EDELWEISS data to derive a limit on the cross-section for spin-independent interaction of WIMPs and nucleons as a function of WIMP mass, using standard nuclear physics and astrophysical assumptions. This limit excludes at more than 99.8% CL a WIMP candidate with a mass of 44 GeV/
c
2 and a cross-section of 5.4×10
−6 pb, as reported by the DAMA Collaboration. A first sample of supersymmetric models are also excluded at 90% CL.
We present the measured baseline ionization resolution of a HEMT-based cryogenic charge amplifier coupled to a CDMS-II detector. The amplifier has been developed to allow massive semiconductor dark ...matter detectors to retain background discrimination at the low recoil energies produced by low-mass WIMPs. We find a calibrated baseline ionization resolution of σE=91eVee. To our knowledge, this is the best direct ionization resolution achieved with such massive (≈150 pF capacitance) radiation detectors.
The LUMINEU is designed to investigate the possibility to search for neutrinoless double beta decay in 100 Mo by means of a large array of scintillating bolometers based on ZnMoO4 crystals enriched ...in 100 Mo. High energy resolution and relatively fast detectors, which are able to measure both the light and the heat generated upon the interaction of a particle in a crystal, are very promising for the recognition and rejection of background events. We present the LUMINEU concepts and the experimental results achieved aboveground and underground with large-mass natural and enriched crystals. The measured energy resolution, the α/β discrimination power and the radioactive internal contamination are all within the specifications for the projected final LUMINEU sensitivity. Simulations and preliminary results confirm that the LUMINEU technology can reach zero background in the region of interest (around 3 MeV) with exposures of the order of hundreds kgxyears, setting the bases for a next generation 0v2β decay experiment capable to explore the inverted hierarchy region of the neutrino mass pattern.
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