41 research outputs found
Improvement of radiopurity level of enriched CdWO and ZnWO crystal scintillators by recrystallization
As low as possible radioactive contamination of a detector plays a crucial
role to improve sensitivity of a double beta decay experiment. The radioactive
contamination of a sample of CdWO crystal scintillator by thorium
was reduced by a factor , down to the level 0.01 mBq/kg
(Th), by exploiting the recrystallization procedure. The total alpha
activity of uranium and thorium daughters was reduced by a factor ,
down to 1.6 mBq/kg. No change in the specific activity (the total
activity and Th) was observed in a sample of ZnWO crystal produced
by recrystallization after removing mm surface layer of the
crystal.Comment: 14 pages, 5 figures and 2 table
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
Regioselectivity of Arylation of 2,3’-Biquinolyl Dianion
The dianion of 2,3’-biquinolyl with aryl- and hetaryl halides forms the products of arylation to 4’-position, which on treatment with alkyl halides or water yield 1’-alkyl-1’,4’dihydro-2,3’-biquinolyls or 4’-aryl-1’,4’-dihydro-2,3’-biquinolyls respectively. The oxidation of the latter leads to 4’-aryl-2,3’-biquinolyls. The cation dependence of the arylation is shown