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CUPID-0 is the first large mass array of enriched Zn\\[^{82}\\]Se scintillating low temperature calorimeters, operated at LNGS since 2017. During its first scientific runs, CUPID-0 collected an exposure of 9.95 kg year. Thanks to the excellent rejection of \\[\\alpha \\] particles, we attained the lowest background ever measured with thermal detectors in the energy region where we search for the signature of \\[^{82}\\hbox {Se}\\] neutrinoless double beta decay. In this work we develop a model to reconstruct the CUPID-0 background over the whole energy range of experimental data. We identify the background sources exploiting their distinctive signatures and we assess their extremely low contribution [down to \\[\\sim 10^{-4}\\] counts/(keV kg year)] in the region of interest for \\[^{82}\\hbox {Se}\\] neutrinoless double beta decay search. This result represents a crucial step towards the comprehension of the background in experiments based on scintillating calorimeters and in next generation projects such as CUPID.

We present the performances of a 330 g zinc molybdate (ZnMoO 4 ) crystal working as scintillating bolometer as a possible candidate for a next generation experiment to search for neutrinoless double beta decay of 100 Mo. The energy resolution, evaluated at the 2615 keV γ -line of 208 Tl, is 6.3 keV FWHM. The internal radioactive contaminations of the ZnMoO 4 were evaluated as <6 μBq/kg ( 228 Th) and 27±6 μBq/kg ( 226 Ra). We also present the results of the α vs β / γ discrimination, obtained through the scintillation light as well as through the study of the shape of the thermal signal alone.

Compelling experimental evidences of neutrino oscillations and their implication that neutrinos are massive particles have given neutrinoless double beta decay ( β β 0 ν ) a central role in astroparticle physics. In fact, the discovery of this elusive decay would be a major breakthrough, unveiling that neutrino and antineutrino are the same particle and that the lepton number is not conserved. It would also impact our efforts to establish the absolute neutrino mass scale and, ultimately, understand elementary particle interaction unification. All current experimental programs to search for β β 0 ν are facing with the technical and financial challenge of increasing the experimental mass while maintaining incredibly low levels of spurious background. The new concept described in this paper could be the answer which combines all the features of an ideal experiment: energy resolution, low cost mass scalability, isotope choice flexibility and many powerful handles to make the background negligible. The proposed technology is based on the use of arrays of silicon detectors cooled to 120 K to optimize the collection of the scintillation light emitted by ultra-pure crystals. It is shown that with a 54 kg array of natural CaMoO 4 scintillation detectors of this type it is possible to yield a competitive sensitivity on the half-life of the β β 0 ν of 100 Mo as high as ∼ 10 24  years in only 1 year of data taking. The same array made of 40 Ca nat MoO 4 scintillation detectors (to get rid of the continuous background coming from the two neutrino double beta decay of 48 Ca) will instead be capable of achieving the remarkable sensitivity of ∼ 10 25  years on the half-life of 100 Mo β β 0 ν in only 1 year of measurement.

Next generation calorimetric experiments for the search of rare events rely on the detection of tiny amounts of light (of the order of 20 optical photons) to discriminate and reduce background sources and improve sensitivity. Calorimetric detectors are the simplest solution for photon detection at cryogenic (mK) temperatures. The development of silicon based light detectors with enhanced performance thanks to the use of the Neganov–Luke effect is described. The aim of this research line is the production of high performance detectors with industrial-grade reproducibility and reliability.

The Cryogenic Underground Observatory for Rare Events (CUORE) is a bolometric experiment for neutrinoless double-beta decay in 130 Te search, currently taking data at the underground facility of Laboratori Nazionali del Gran Sasso (LNGS). The CUORE cryostat successfully cooled down a mass of about 1 ton at ∼ 7 mK , delivering a uniform and constant base temperature. This result marks a fundamental milestone in low-temperature detector techniques, opening the path for future ton-scale bolometric experiments searching for rare events. In this paper, we present the CUORE cryogenic infrastructure, briefly describing its critical subsystems.

A convincing observation of neutrino-less double beta decay (0vDBD) relies on the possibility of operating high-energy resolution detectors in background-free conditions. Scintillating cryogenic calorimeters are one of the most promising tools to fulfill the requirements for a next-generation experiment. Several steps have been taken to demonstrate the maturity of this technique, starting form the successful experience of CUPID-0. The CUPID-0 experiment collected almost 10 kg y of exposure, running 26 Zn82Se crystals during two years of continuous detector operation. The complete rejection of the dominant α background was demonstrated, measuring the lowest counting rate in the region of interest for this technique. Furthermore, the most stringent limit on the 82Se 0vDBD was established. In this contribution we present the final results of CUPID-0 phase-I, including a detailed model of the background and the measurement of the 2vDBD half-life.

Abstract The Review summarizes much of particle physics and cosmology. Using data from previous editions, plus 2,143 new measurements from 709 papers, we list, evaluate, and average measured properties of gauge bosons and the recently discovered Higgs boson, leptons, quarks, mesons, and baryons. We summarize searches for hypothetical particles such as supersymmetric particles, heavy bosons, axions, dark photons, etc. Particle properties and search limits are listed in Summary Tables. We give numerous tables, figures, formulae, and reviews of topics such as Higgs Boson Physics, Supersymmetry, Grand Unified Theories, Neutrino Mixing, Dark Energy, Dark Matter, Cosmology, Particle Detectors, Colliders, Probability and Statistics. Among the 120 reviews are many that are new or heavily revised, including a new review on Machine Learning, and one on Spectroscopy of Light Meson Resonances. The Review is divided into two volumes. Volume 1 includes the Summary Tables and 97 review articles. Volume 2 consists of the Particle Listings and contains also 23 reviews that address specific aspects of the data presented in the Listings. The complete Review (both volumes) is published online on the website of the Particle Data Group (pdg.lbl.gov) and in a journal. Volume 1 is available in print as the PDG Book. A Particle Physics Booklet with the Summary Tables and essential tables, figures, and equations from selected review articles is available in print, as a web version optimized for use on phones, and as an Android app.

The Cryogenic Underground Observatory for Rare Events (CUORE) experiment is presently in the final phases of its commissioning at the Gran Sasso Underground Laboratory (Italy). The CUORE cryogenic system will have to guarantee the optimal operation temperature of the detector (∼ 10 mK) for a live-time of 5 years. Furthermore, to avoid radioactive background, about 7 tonnes of lead are cooled to below 4 K and only few construction materials are acceptable. The CUORE detector will be by far the largest mass ever cooled to 10 mK. A description of the CUORE cryostat is presented and the specific characteristics and the performances are illustrated. The results of the (recently concluded) cryostat commissioning are also reported. They show that the CUORE cryostat is now ready to host the detector, thus confirming the possibility of realizing large bolometric arrays for rare event physics.

Low temperature thermal detectors with particle identification capabilities are among the best detectors for next generation experiments for the search of neutrinoless double beta decay. Thermal detectors allow to reach excellent energy resolution and to optimize the detection efficiency, while the possibility to identify the interacting particle allows to greatly reduce the background. Tellurium dioxide is one of the favourite compounds since it has long demonstrated the first two features and could reach the third through Cherenkov emission tagging [1]. A new generation of cryogenic light detectors are however required to detect the few Cherenkov photons emitted by electrons of few MeV energy. Preliminary measurements with new Si light detectors demonstrated a clear event-by-event discrimination between alpha and beta/gamma interactions at the 130Te neutrinoless double beta decay Q-value (2528 keV).

We present the performances of a 330 g zinc molybdate (ZnMoO.sub.4) crystal working as scintillating bolometer as a possible candidate for a next generation experiment to search for neutrinoless double beta decay of .sup.100Mo. The energy resolution, evaluated at the 2615 keV [gamma]-line of .sup.208Tl, is 6.3 keV FWHM. The internal radioactive contaminations of the ZnMoO.sub.4 were evaluated as <6 [mu]Bq/kg (.sup.228Th) and 27±6 [mu]Bq/kg (.sup.226Ra). We also present the results of the [alpha] vs [beta]/[gamma] discrimination, obtained through the scintillation light as well as through the study of the shape of the thermal signal alone.