[en] TeO₂ bolometers have been used for many years to search for neutrinoless double beta decay in 130-Te. CUORE, a tonne-scale TeO₂ detector array, recently published the most sensitive limit on the half-life, T_1/2^0ν>1.5×10²⁵ yr, which corresponds to an upper bound of 140−400 meV on the effective Majorana mass of the neutrino. While it makes CUORE a world-leading experiment looking for neutrinoless double beta decay, it is not the only study that CUORE will contribute to in the field of nuclear and particle physics. As already done over the years with many small-scale experiments, CUORE will investigate both rare decays (such as the two-neutrino double beta decay of ¹³⁰Te and the hypothesized electron capture in ¹²³Te), and rare processes (e.g., dark matter and axion interactions). This paper describes some of the achievements of past experiments that used TeO₂ bolometers, and perspectives for CUORE.

[en] The Cryogenic Underground Observatory for Rare Events (CUORE) is the first bolometric experiment searching for neutrinoless double beta decay that has been able to reach the 1-ton scale. In this talk we present the neutrinoless doube beta decay results of CUORE from examining a total TeO₂ exposure of 86.3 kg yr, characterized by an effective energy resolution of 7.7 keV FWHM and a background in the region of interest of 0.014 counts/(keV kg yr). In this physics run, CUORE placed a lower limit on the decay half-life of ¹³⁰Te > 1.3 × 10²⁵ yr (90% C.L.). We then discuss the additional improvements in the detector performance achieved in 2018 and the latest update on the evaluation of the background budget.

[en] The Cryogenic Underground Observatory for Rare Events (CUORE) is the most massive bolometric experiment searching for neutrino-less double beta (0νββ) decay. The detector consists of an array of 988 TeO₂ crystals (742 kg) arranged in a compact cylindrical structure of 19 towers. Here, this paper will describe the CUORE experiment, including the cryostat, and present the detector performance during the first year of running. Additional detail will describe the effort made in improving the energy resolution in the ¹³⁰Te 0νββ decay region of interest (ROI) and the suppression of backgrounds. A description of work to lower the energy threshold in order to give CUORE the sensitivity to search for other rare events, such as dark matter, will also be provided.

[en] We report new results from the search for neutrinoless double-beta decay in ${}^{130}$Te with the CUORE detector. This search benefits from a four-fold increase in exposure, lower trigger thresholds and analysis improvements relative to our previous results. We observe a background of $(1.38\pm <!--\; ??\; -->0.07)\cdot <!--\; ???\; -->{10}^{-<!--\; ???\; -->2}$ counts$/($keV$\cdot <!--\; ???\; -->$kg$\cdot <!--\; ???\; -->$yr$)$ in the $0\mathrm{\nu <!--\; ??\; -->}\mathrm{\beta <!--\; ??\; -->}\mathrm{\beta <!--\; ??\; -->}$ decay region of interest and, with a total exposure of 372.5 kg$\cdot <!--\; ???\; -->$yr, we attain a median exclusion sensitivity of $1.7\cdot <!--\; ???\; -->{10}^{25}$ yr. We find no evidence for $0\mathrm{\nu <!--\; ??\; -->}\mathrm{\beta <!--\; ??\; -->}\mathrm{\beta <!--\; ??\; -->}$ decay and set a $90\mathrm{\%<!--\; \%\; -->}$ CI Bayesian lower limit of $3.2\cdot <!--\; ???\; -->{10}^{25}$ yr on the ${}^{130}$Te half-life for this process. In the hypothesis that $0\mathrm{\nu <!--\; ??\; -->}\mathrm{\beta <!--\; ??\; -->}\mathrm{\beta <!--\; ??\; -->}$ decay is mediated by light Majorana neutrinos, this results in an upper limit on the effective Majorana mass of 75-350 meV, depending on the nuclear matrix elements used.

[en] Bolometric experiments searching for rare events usually require an extremely low radioactive background to prevent spurious signals from mimicking those of interest, spoiling the sensitivity of the apparatus. In such contexts, radioactive sources cannot be used to produce a known signal to calibrate the measured energy spectrum during data taking. In this paper we present an instrument designed to generate ultra-stable and very precise calibrating pulses, which can be used to stabilize the response of bolometers during data taking. The instrument is characterized by the presence of multi-outputs, a completely programmable pulse width and amplitude and a dedicated daisy-chained optical trigger line. It can be fully controlled and monitored remotely via CAN bus protocol. An energy resolution of the order of 20 eV FWHM at 1 MeV (2 eV FWHM at 10 keV) and a thermal stability of the order of 0.1 ppm/^oC have been achieved. The device can also provide an adjustable power to compensate the low frequency thermal fluctuations that typically occur in cryogenic experiments.

[en] Neutrino oscillation experiments proved that neutrinos have mass and this enhanced the interest in neutrinoless double-beta decay (0νββ). The observation of this very rare hypothetical decay would prove the leptonic number violation and would give indications about neutrinos mass hierarchy and absolute mass scale. CUORE (Cryogenic Underground Observatory for Rare Events) is an array of 988 crystals of TeO_2, for a total sensitive mass of 741 kg. Its goal is the observation of 0νββ of "1"3"0Te. The crystals, placed into the a dilution cryostat, are operated as bolometers at a temperature close to 10 mk. CUORE commissioning phase has been concluded recently in Gran Sasso National Laboratory, Italy, and data taking is expected to start in spring 2017. If target background rate is reached (0.01counts/day/keV/kg), the sensibility of CUORE will be, in five years of data taking, T_1_/_2 ≃ 10 "2"6years (1σ CL). In order to test the quality of materials and optimize the construction procedures, the collaboration realized CUORE-0, that took data from spring of 2013 to summer 2015. Here, after a brief description of CUORE, I report its commissioning status and CUORE-0 results.

[en] CUPID will be a next generation experiment searching for the neutrinoless double β decay, whose discovery would establish the Majorana nature of the neutrino. Based on the experience achieved with the CUORE experiment, presently taking data at LNGS, CUPID aims to reach a background free environment by means of scintillating Li${}_2$${}^{100}$MoO${}_4$ crystals coupled to light detectors. Indeed, the simultaneous heat and light detection allows us to reject the dominant background of α particles, as proven by the CUPID-0 and CUPID-Mo demonstrators. In this work we present the results of the first test of the CUPID baseline module. In particular, we propose a new optimized detector structure and light sensors design to enhance the engineering and the light collection, respectively. We characterized the heat detectors, achieving an energy resolution of (5.9 ± 0.2) keV FWHM at the Q-value of ${}^{100}$Mo (about 3034 keV). We studied the light collection of the baseline CUPID design with respect to an alternative configuration which features gravity-assisted light detectors' mounting. In both cases we obtained an improvement in the light collection with respect to past measures and we validated the particle identification capability of the detector, which ensures an α particle rejection higher than 99.9%, fully satisfying the requirements for CUPID.

[en] The CUORE experiment is a large bolometric array searching for the lepton number violating neutrino-less double beta decay (0νββ) in the isotope ${}^{130}$Te. In this work we present the latest results on two searches for the double beta decay (DBD) of ${}^{130}$Teto the first 0${}_2^{+}$ excited state of ${}^{130}$Xe: the 0νββ decay and the Standard Model-allowed two-neutrinos double beta decay (2νββ). Both searches are based on a 372.5 kg × yr TeO${}_2$ exposure. The de-excitation gamma rays emitted by the excited Xe nucleus in the final state yield a unique signature, which can be searched for with low background by studying coincident events in two or more bolometers. The closely packed arrangement of the CUORE crystals constitutes a significant advantage in this regard. The median limit setting sensitivities at 90% Credible Interval (C.I.) of the given searches were estimated as S${}_{1/2}^{0\mathrm{\nu <!--\; ??\; -->}}$ = 5.6 × 10${}^{24}$, yr for the 0νββ decay and S${}_{1/2}^{2\mathrm{\nu <!--\; ??\; -->}}$ = 2.1 × 10${}^{24}$, yr for the 2νββ decay. No significant evidence for either of the decay modes was observed and a Bayesian lower bound at 90% C.I. on the decay half lives is obtained as: (T${}_{1/2}$)${}_{0_2^{+}}^{0\mathrm{\nu <!--\; ??\; -->}}$ > 5.9 × 10${}^{24}$, yr for the 0νββ mode and (T${}_{1/2}$)${}_{0_2^{+}}^{2\mathrm{\nu <!--\; ??\; -->}}$ > 1.3 × 10${}^{24}$, yr for the 2νββ mode. These represent the most stringent limits on the DBD of ${}^{130}$Te to excited states and improve by a factor ∼ 5 the previous results on this process.

[en] Neutrinoless Double Beta Decay (0νββ) is a rare nuclear transition that if it occurs at all it will be very important for the exploration of the inverted hierarchy region of the neutrino mass pattern. The Cryogenic Underground Observatory for Rare Events (CUORE) is an experiment that aims to search for such a transition in "1"3"0Te together with other rare processes. In the present paper we will describe the basic features of CUORE Experiment, the status of the experiment as well as the latest results obtained from CUORE-0 detector, a smaller scale experiment constructed to test and demonstrate the expected performances of CUORE.

[en] An analytical model for the generation of β-delayed γ-ray spectra following thermal-neutron-induced fission of mixed samples of ²³⁵U and ²³⁹Pu is presented. Using an energy-dependent figure-of-merit to designate the spectral regions employed in the assay, the unique temporal β-delayed γ-ray signatures are utilized to determine the fraction of ²³⁹Pu in a mixed U-Pu sample. By evaluating the β-delayed γ-ray temporal signatures of both ²³⁵U and ²³⁹Pu within a 3 keV energy bin, traditional sources of systematic uncertainty in quantitative assay using β-delayed γ-ray signals, such as self-attenuation of the sample and energy-dependent γ-ray detection efficiency, are significantly reduced. The effects of the time-dependent Compton-continuum and growth of longer-lived nuclides on the quantitative assessment are explored. This methodology represents a promising extension of the conventional means of analysis for quantitative assay of fissile materials using β-delayed γ-ray signatures.