Characterization of cubic Li$$_{2}$$$$^{100}$$MoO$$_4$$ crystals for the CUPID experiment

Abstract

The CUPID Collaboration is designing a tonne-scale, background-free detector to search for double beta decay with sufficient sensitivity to fully explore the parameter space corresponding to the inverted neutrino mass hierarchy scenario. One of the CUPID demonstrators, CUPID-Mo, has proved the potential of enriched Li$$_{2}$$ 2 $$^{100}$$ 100 MoO$$_4$$ 4 crystals as suitable detectors for neutrinoless double beta decay search. In this work, we characterised cubic crystals that, compared to the cylindrical crystals used by CUPID-Mo, are more appealing for the construction of tightly packed arrays. We measured an average energy resolution of ($$6.7\pm 0.6$$ 6.7 ± 0.6 ) keV FWHM in the region of interest, approaching the CUPID target of 5 keV FWHM. We assessed the identification of $$\alpha $$ α particles with and without a reflecting foil that enhances the scintillation light collection efficiency, proving that the baseline design of CUPID already ensures a complete suppression of this $$\alpha $$ α -induced background contribution. We also used the collected data to validate a Monte Carlo simulation modelling the light collection efficiency, which will enable further optimisations of the detector.

Background identification in cryogenic calorimeters through $$\alpha -\alpha $$ delayed coincidences

“…For example, in the analysis of CUORE data [30], delayed coincidences could help to better constrain the background sources [31] and to reject the time-correlated events falling in the region of interest. Moreover, the R&D activities for CUPID [32,33], CUPID-Mo [34][35][36], and in general the experiments searching for rare events can profit from this technique to study the radioactive contaminations of detector components and to select ultra-pure materials, with also the possibility to analyze other decay sequences in 238 U, 232 Th and 235 U chains [37]. Finally, the analysis of delayed coinci-dences in CUPID-0 allowed to measure the half-life of 216 Po [38].…”

Novel technique for the study of pileup events in cryogenic bolometers

“…It is thus possible that some events in the various intervals deviate from the average behavior, despite the identical settings of the input wave forms. standard CUORE workflow [19], which has also been adopted as the starting point for the main analysis of the LMO detectors [13]. These analysis tools are well established and have been applied over the years on multiple detectors [20,21].…”

“…An array of LMO crystals was deployed to study the performance of CUPID-like detectors, with crystals of similar dimension and shape to those that are intended to be used in the actual experiment [13]. This deployment is one of a series of bolometric tests planned to optimize the final technical design for CUPID.…”

Final results of CALDER: kinetic inductance light detectors to search for rare events

“…These sensors offer a typical baseline resolution of 50-60 eV RMS with rise time of 1-5 ms (see, e.g., Refs. [23,25,26] and references therein). A detector of 16 cm 2 in an optimized configuration reached an ultimate resolution of 20 eV RMS with rise time of 0.8 ms [27].…”