72 research outputs found
Search for double beta decay of 106Cd with an enriched 106CdWO4 crystal scintillator in coincidence with CdWO4 scintillation counters
Studies on double beta decay processes in 106Cd were performed by using a cadmium tungstate scintillator enriched in 106Cd at 66% (106CdWO4) with two CdWO4 scintillation counters (with natural Cd composition). No effect was observed in the data that accumulated over 26033 h. New improved half-life limits were set on the different channels and modes of the 106Cd double beta decay at level of lim T_1/2 ∼ 10^20 − 10^22 yr. The limit for the two neutrino electron capture 2νECβ with positron emission in 106Cd to the ground state of 106Pd, T_1/2 ≥ 2.1 × 10^21 yr, was set by the analysis of the 106CdWO4 data in coincidence with the energy release 511 keV in both CdWO 4 counters. The sensitivity approaches the theoretical predictions for the decay half-life that are in the range T_1/2 ∼ 10^21 − 10^22 yr. The resonant neutrinoless double-electron capture to the 2718 keV excited state of 106Pd is restricted at the level of T_1/2 (0ν2K) ≥ 2.9 × 10^21 yr
LiMoO Scintillating Bolometers for Rare-Event Search Experiments
We report on the development of scintillating bolometers based on lithium
molybdate crystals containing molybdenum depleted in the double- active
isotope Mo (LiMoO). We used two
LiMoO cubic samples, 45 mm side and 0.28 kg each,
produced following purification and crystallization protocols developed for
double- search experiments with Mo-enriched LiMoO
crystals. Bolometric Ge detectors were utilized to register scintillation
photons emitted by the LiMoO crystal
scintillators. The measurements were performed in the CROSS cryogenic set-up at
the Canfranc underground laboratory (Spain). We observed that the
LiMoO scintillating bolometers are characterized
by excellent spectrometric performance (3--6 keV FWHM at 0.24--2.6 MeV
's), moderate scintillation signal (0.3--0.6 keV/MeV depending on
light collection conditions) and high radiopurity (Th and Ra
activities are below a few Bq/kg), comparable to the best reported results
of low-temperature detectors based on LiMoO with natural or
Mo-enriched molybdenum content. Prospects of
LiMoO bolometers for use in rare-event search
experiments are briefly discussed.Comment: Prepared for submission to MDPI Sensors; 16 pages, 7 figures, and 3
table
Final results on the 0νββ decay half-life limit of Mo from the CUPID-Mo experiment
The CUPID-Mo experiment to search for 0νββ decay in 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 0νββ decay experiment. CUPID-Mo was comprised of 20 enriched LiMoO 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 (Mo 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 Mo 0νββ decay half-life of T >1.8×10 year (stat. + syst.) at 90% CI. Under the light Majorana neutrino exchange mechanism this corresponds to an effective Majorana neutrino mass of ⟨m⟩ < (0.28−0.49) eV, dependent upon the nuclear matrix element utilized
The background model of the CUPID-Mo experiment
CUPID-Mo, located in the Laboratoire Souterrain de Modane (France), was a
demonstrator for the next generation decay experiment, CUPID.
It consisted of an array of 20 enriched LiMoO bolometers and
20 Ge light detectors and has demonstrated that the technology of scintillating
bolometers with particle identification capabilities is mature. Furthermore,
CUPID-Mo can inform and validate the background prediction for CUPID. In this
paper, we present a detailed model of the CUPID-Mo backgrounds. This model is
able to describe well the features of the experimental data and enables studies
of the decay and other processes with high precision. We also
measure the radio-purity of the LiMoO crystals which are
found to be sufficient for the CUPID goals. Finally, we also obtain a
background index in the region of interest of
3.7(stat)(syst)counts/E/mol/yr,
the lowest in a bolometric decay experiment
A CUPID Li2100MoO4scintillating bolometer tested in the CROSS underground facility
A scintillating bolometer based on a large cubic Li2100MoO4 crystal (45 mm side) and a Ge wafer (scintillation detector) has been operated in the CROSS cryogenic facility at the Canfranc underground laboratory in Spain. The dual-readout detector is a prototype of the technology that will be used in the next-generation 0¿2ß experiment CUPID . The measurements were performed at 18 and 12 mK temperature in a pulse tube dilution refrigerator. This setup utilizes the same technology as the CUORE cryostat that will host CUPID and so represents an accurate estimation of the expected performance. The Li2100MoO4 bolometer shows a high energy resolution of 6 keV FWHM at the 2615 keV ¿ line. The detection of scintillation light for each event triggered by the Li2100MoO4 bolometer allowed for a full separation (~8s) between ¿(ß) and a events above 2 MeV . The Li2100MoO4 crystal also shows a high internal radiopurity with 228Th and 226Ra activities of less than 3 and 8 µBq/kg, respectively. Taking also into account the advantage of a more compact and massive detector array, which can be made of cubic-shaped crystals (compared to the cylindrical ones), this test demonstrates the great potential of cubic Li2100MoO4 scintillating bolometers for high-sensitivity searches for the 100Mo 0¿2ß decay in CROSS and CUPID projects
A first test of CUPID prototypal light detectors with NTD-Ge sensors in a pulse-tube cryostat
CUPID is a next-generation bolometric experiment aiming at searching for
neutrinoless double-beta decay with ~250 kg of isotopic mass of Mo. It
will operate at 10 mK in a cryostat currently hosting a similar-scale
bolometric array for the CUORE experiment at the Gran Sasso National Laboratory
(Italy). CUPID will be based on large-volume scintillating bolometers
consisting of Mo-enriched LiMoO crystals, facing thin
Ge-wafer-based bolometric light detectors. In the CUPID design, the detector
structure is novel and needs to be validated. In particular, the CUORE cryostat
presents a high level of mechanical vibrations due to the use of pulse tubes
and the effect of vibrations on the detector performance must be investigated.
In this paper we report the first test of the CUPID-design bolometric light
detectors with NTD-Ge sensors in a dilution refrigerator equipped with a pulse
tube in an above-ground lab. Light detectors are characterized in terms of
sensitivity, energy resolution, pulse time constants, and noise power spectrum.
Despite the challenging noisy environment due to pulse-tube-induced vibrations,
we demonstrate that all the four tested light detectors comply with the CUPID
goal in terms of intrinsic energy resolution of 100 eV RMS baseline noise.
Indeed, we have measured 70--90 eV RMS for the four devices, which show an
excellent reproducibility. We have also obtained outstanding energy resolutions
at the 356 keV line from a Ba source with one light detector achieving
0.71(5) keV FWHM, which is -- to our knowledge -- the best ever obtained when
compared to detectors of any technology in this energy range.Comment: Prepared for submission to JINST; 16 pages, 7 figures, and 1 tabl
Twelve-crystal prototype of LiMoO scintillating bolometers for CUPID and CROSS experiments
An array of twelve 0.28 kg lithium molybdate (LMO) low-temperature bolometers
equipped with 16 bolometric Ge light detectors, aiming at optimization of
detector structure for CROSS and CUPID double-beta decay experiments, was
constructed and tested in a low-background pulse-tube-based cryostat at the
Canfranc underground laboratory in Spain. Performance of the scintillating
bolometers was studied depending on the size of phonon NTD-Ge sensors glued to
both LMO and Ge absorbers, shape of the Ge light detectors (circular vs.
square, from two suppliers), in different light collection conditions (with and
without reflector, with aluminum coated LMO crystal surface). The scintillating
bolometer array was operated over 8 months in the low-background conditions
that allowed to probe a very low, Bq/kg, level of the LMO crystals
radioactive contamination by Th and Ra.Comment: Prepared for submission to JINST; 23 pages, 9 figures, and 4 table
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