The CUORE experiment, a ton-scale cryogenic bolometer array, recently began operation at the Laboratori Nazionali del Gran Sasso in Italy. The array represents a significant advancement in this technology, and in this work we apply it for the first time to a high-sensitivity search for a lepton-number-violating process: ^{130}Te neutrinoless double-beta decay. Examining a total TeO_{2} exposure of 86.3 kg yr, characterized by an effective energy resolution of (7.7±0.5)  keV FWHM and a background in the region of interest of (0.014±0.002)  counts/(keV kg yr), we find no evidence for neutrinoless double-beta decay. Including systematic uncertainties, we place a lower limit on the decay half-life of T_{1/2}^{0ν}(^{130}Te)>1.3×10^{25}  yr (90% C.L.); the median statistical sensitivity of this search is 7.0×10^{24}  yr. Combining this result with those of two earlier experiments, Cuoricino and CUORE-0, we find T_{1/2}^{0ν}(^{130}Te)>1.5×10^{25}  yr (90% C.L.), which is the most stringent limit to date on this decay. Interpreting this result as a limit on the effective Majorana neutrino mass, we find m_{ββ}<(110-520)  meV, where the range reflects the nuclear matrix element estimates employed.

CUORE is a proposed tightly packed array of 1000 TeO2 bolometers, each being a cube 5 cm on a side with a mass of 760 g. The array consists of 25 vertical towers, arranged in a square of 5 towers×5 towers, each containing 10 layers of four crystals. The design of the detector is optimized for ultralow-background searches: for neutrinoless double-beta decay of 130Te (33.8% abundance), cold dark matter, solar axions, and rare nuclear decays. A preliminary experiment involving 20 crystals 3×3×6 cm3 of 340 g has been completed, and a single CUORE tower is being constructed as a smaller-scale experiment called CUORICINO. The expected performance and sensitivity, based on Monte Carlo simulations and extrapolations of present results, are reported

The PTOLEMY project aims to develop a scalable design for a Cosmic Neutrino Background (CNB) detector, the first of its kind and the only one conceived that can look directly at the image of the Universe encoded in neutrino background produced in the first second after the Big Bang. The scope of the work for the next three years is to complete the conceptual design of this detector and to validate with direct measurements that the nonneutrino backgrounds are below the expected cosmological signal. In this paper we discuss in details the theoretical aspects of the experiment and its physics goals. In particular, we mainly address three issues. First we discuss the sensitivity of PTOLEMY to the standard neutrino mass scale. We then study the perspectives of the experiment to detect the CNB via neutrino capture on tritium as a function of the neutrino mass scale and the energy resolution of the apparatus. Finally, we consider an extra sterile neutrino with mass in the eV range, coupled to the active states via oscillations, which has been advocated in view of neutrino oscillation anomalies. This extra state would contribute to the tritium decay spectrum, and its properties, mass and mixing angle, could be studied by analyzing the features in the beta decay electron spectrum.

Corresponding author exist scenarios in which the effective Majorana mass of the electron neutrino could be larger than 0.05 eV. Recent developments in detector technology make the observation of 0 νββ decay at this scale now feasible. For recent comprehensive experimental and theoretical reviews see [4][5][6]. Optimism that a direct observation of 0 νββ decay is possible was greatly enhanced by the observation and measurement of the oscillations of atmospheric neutrinos [7], the confirmation by SuperKamiokande [8] of the deficit of 8 B neutrinos observed by the chlorine experiment [9], the observed deficit of p-p neutrinos by SAGE [10] and GALEX [11], and the results of the SNO experiment [12] that clearly showed that the total flux of 8 B neutrinos from the sun predicted by Bahcall and his coworkers [13] is correct. Finally, the data from the KamLAND