63 research outputs found
Final results on the 0ÎœÎČÎČ decay half-life limit of Mo from the CUPID-Mo experiment
The CUPID-Mo experiment to search for 0ÎœÎČÎČ 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 0ÎœÎČÎČ decay experiment. CUPID-Mo was comprised of 20 enriched LiMoO scintillating calorimeters, each with a mass of âŒ0.2 kg, operated at âŒ20 mK. We present here the final analysis with the full exposure of CUPID-Mo (Mo exposure of 1.47 kgĂyear) used to search for lepton number violation via 0ÎœÎČÎČ 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 0ÎœÎČÎČ decay half-life of T >1.8Ă10 year (stat. + syst.) at 90% CI. Under the light Majorana neutrino exchange mechanism this corresponds to an effective Majorana neutrino mass of âšmâ© < (0.28â0.49) 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
Precise measurement of 2 ÎœÎČÎČ decay of 100 Mo with the CUPID-Mo detection technology
We report the measurement of the two-neutrino double-beta (2 ÎœÎČÎČ) 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 kgĂ day, the half-life of 100Mo is determined to be T1/22Îœ=[7.12-0.14+0.18(stat.)±0.10(syst.)]Ă1018 years. This is the most accurate determination of the 2 ÎœÎČÎČ half-life of 100Mo to date
Foraging Fidelity as a Recipe for a Long Life: Foraging Strategy and Longevity in Male Southern Elephant Seals
Identifying individual factors affecting life-span has long been of interest for biologists and demographers: how do some individuals manage to dodge the forces of mortality when the vast majority does not? Answering this question is not straightforward, partly because of the arduous task of accurately estimating longevity in wild animals, and of the statistical difficulties in correlating time-varying ecological covariables with a single number (time-to-event). Here we investigated the relationship between foraging strategy and life-span in an elusive and large marine predator: the Southern Elephant Seal (Mirounga leonina). Using teeth recovered from dead males on Ăźles Kerguelen, Southern Ocean, we first aged specimens. Then we used stable isotopic measurements of carbon () in dentin to study the effect of foraging location on individual life-span. Using a joint change-point/survival modelling approach which enabled us to describe the ontogenetic trajectory of foraging, we unveiled how a stable foraging strategy developed early in life positively covaried with longevity in male Southern Elephant Seals. Coupled with an appropriate statistical analysis, stable isotopes have the potential to tackle ecological questions of long standing interest but whose answer has been hampered by logistic constraints
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 0Âż2Ă 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 Âż line. The detection of scintillation light for each event triggered by the Li2100MoO4 bolometer allowed for a full separation (~8s) between Âż(Ă) 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 ”Bq/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 0Âż2Ă 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
- âŠ