C-H FUNCTIONALIZATION IN THE SYNTHESIS OF CARBORANE-BASED POLYAZAHATEROCYCLIC HYDROCARBONS

Among the versatile organic fluorophores, special attention is known to be paid to photoactive organoboron compounds, in particular heterocyclic derivatives of carborane. According to numerous studies, the ortho-carborane scaffold is considered to be an “element-block” for preparing solid state luminescent materials due to its excellent suppression of aggregation-caused quenching (ACQ). Carborane-based materials also currently find an application in catalysis, medicine, supramolecular chemistry and photovoltaics.The research was financially supported by the Russian Science Foundation (Project no. 20-43-01004), a bilateral Russian Science Foundation (RSF) – Fund for Scientific Research Flanders (FWO) project, and the Francqui Foundation

Precise measurement of 2 νββ decay of 100 Mo with the CUPID-Mo detection technology

We report the measurement of the two-neutrino double-beta (2 νββ) 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 kg× day, the half-life of 100Mo is determined to be T1/22ν=[7.12-0.14+0.18(stat.)±0.10(syst.)]×1018 years. This is the most accurate determination of the 2 νββ half-life of 100Mo to date

Final results on the 0νββ decay half-life limit of 100^{100} Mo from the CUPID-Mo experiment

The CUPID-Mo experiment to search for 0νββ decay in $^{100}$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 Li$_2^{100}$MoO$_4$ 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 ($^{100}$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 $^{100}$Mo 0νββ decay half-life of T$^{0ν}_{1/2}$ >1.8×10$^{24}$ year (stat. + syst.) at 90% CI. Under the light Majorana neutrino exchange mechanism this corresponds to an effective Majorana neutrino mass of ⟨m$_{ββ}$⟩ < (0.28−0.49) eV, dependent upon the nuclear matrix element utilized

The background model of the CUPID-Mo 0νββ0\nu\beta\beta experiment

CUPID-Mo, located in the Laboratoire Souterrain de Modane (France), was a demonstrator for the next generation $0\nu\beta\beta$ decay experiment, CUPID. It consisted of an array of 20 enriched Li$_{2}$$^{100}$MoO$_4$ bolometers and 20 Ge light detectors and has demonstrated that the technology of scintillating bolometers with particle identification capabilities is mature. Furthermore, CUPID-Mo can inform and validate the background prediction for CUPID. In this paper, we present a detailed model of the CUPID-Mo backgrounds. This model is able to describe well the features of the experimental data and enables studies of the $2\nu\beta\beta$ decay and other processes with high precision. We also measure the radio-purity of the Li$_{2}$$^{100}$MoO$_4$ 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$^{+0.9}_{-0.8}$(stat)$^{+1.5}_{-0.7}$(syst)$\times10^{-3}$counts/$\Delta$E$_{FWHM}$/mol$_{iso}$/yr, the lowest in a bolometric $0\nu\beta\beta$ decay experiment

Development of 100^{100}Mo-containing scintillating bolometers for a high-sensitivity neutrinoless double-beta decay search

We report recent achievements in the development of scintillating bolometers to search for neutrinoless double-beta decay of $^{100}$Mo. The presented results have been obtained in the framework of the LUMINEU, LUCIFER and EDELWEISS collaborations, and are now part of the R\&D activities towards CUPID (CUORE Update with Particle IDentification), a proposed next-generation double-beta decay experiment based on the CUORE experience. We have developed a technology for the production of large mass ($\sim$1 kg), high optical quality, radiopure zinc and lithium molybdate crystal scintillators (ZnMoO$_4$ and Li$_2$MoO$_4$, respectively) from deeply purified natural and $^{100}$Mo-enriched molybdenum. The procedure is applied for a routine production of enriched crystals. Furthermore, the technology of a single detector module consisting of a large-volume ($\sim 100$~cm$^3$) Zn$^{100}$MoO$_4$ and Li$_2$$^{100}$MoO$_4$ scintillating bolometer has been established, demonstrating performance and radiopurity that are close to satisfy the demands of CUPID. In particular, the FWHM energy resolution of the detectors at 2615 keV --- near the $Q$-value of the double-beta transition of $^{100}$Mo (3034~keV) --- is $\approx$ 4--10~keV. The achieved rejection of $\alpha$-induced dominant background above 2.6~MeV is at the level of more than 99.9\%. The bulk activity of $^{232}$Th ($^{228}$Th) and $^{226}$Ra in the crystals is below 10 $\mu$Bq/kg. Both crystallization and detector technologies favor Li$_2$MoO$_4$, which was selected as a main element for the realization of a CUPID demonstrator (CUPID-0/Mo) with $\sim$7 kg of $^{100}$Mo

Low thermal gradient Czochralski growth of large MWO4 (M = Zn, Cd) crystals, and microstructural and electronic properties of the (010) cleaved surfaces

The large optical-quality MWO4 (M = Zn, Cd) crystals of mass up to 14 (ZnWO4) and 20 (CdWO4) kg were grown by Low Thermal Gradient Czochralski Technique (LTG Cz). Crystallographic properties of MWO4(010) cleaved surface were evaluated by AFM and RHEED, and electronic structure of the surface was studied using XPS. A system of Kikuchi lines has been observed for cleaved MWO4(010) by RHEED confirming high crystallographic quality of the surface. The XPS valence-band and core-level spectra of MWO4(010) have been measured. The XPS measurements reveal that W and M atoms are in the formal valences 6+ and 2+, respectively, on cleaved MWO4(010) surface