The search for neutrinoless double beta decay (DBD-0ν) is a powerful tool to establish the correct neutrino mass hierarchy and whether the neutrino is a Majorana or Dirac particle. The Milano group has run several experiments using thermal detectors to search for the 130Te DBD-0ν. The Cuoricino experiment consists of an array of 62 TeO2 thermal detectors for a total mass of about 40 kg, by far the largest cryogenic experiment in the world. The detector installation in the Gran Sasso Underground Laboratory has been recently completed. After a test phase the experiment is now taking data and we report here the preliminary results. Cuoricino is the first step toward the CUORE experiment, which will consists of 1000 TeO2 thermal detectors for a total mass of about 760 kg: in this paper we discuss also the physics potential of both stages for what concerns the DBD-0ν search. PACS: 11.30.Fs Lepton number – 14.60.Pq Neutrino mass and mixing – 23.40.Bw Weak interactions in beta decay

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.

The CUORICINO experiment was an array of 62 TeO2 single-crystal bolometers with a total 130Te mass of 11.3kg. The experiment finished in 2008 after more than 3 yr of active operating time. Searches for both 0ν and 2ν double-β decay to the first excited 0+ state in 130Xe were performed by studying different coincidence scenarios. The analysis was based on data representing a total exposure of N(130Te)•t=9.5×1025yr. No evidence for a signal was found. The resulting lower limits on the half-lives are T122ν(130Te→130Xe*)>1. 3×1023yr (90% C.L.), and T120ν(130Te →130Xe*)>9.4×1023yr (90% CL). ©2012 American Physical Society.

We present a search for β+/EC double beta decay of 120Te performed with the CUORICINO experiment, an array of TeO2 cryogenic bolometers. After collecting 0.0573 kg · y of 120Te, we see no evidence of a signal and therefore set the following limits on the half-life: T1/20ν>1.9·1021 y at 90% C.L. for the 0ν mode and T1/22ν>7.6·1019 y at 90% C.L. for the 2ν mode. These results improve the existing limits by almost three orders of magnitude (four in the case of 0ν mode). © 2011 Published by Elsevier B.V.

We report the final result of the CUORICINO experiment. Operated between 2003 and 2008, with a total exposure of 19.75 kg · y of 130Te, CUORICINO was able to set a lower bound on the 130Te 0νββ half-life of 2.8 × 1024 years at 90% C.L. The limit here reported includes the effects of systematic uncertainties that are examined in detail in the paper. The corresponding upper bound on the neutrino Majorana mass is in the range 300-710 meV, depending on the adopted nuclear matrix element evaluation. © 2011 Elsevier B.V. All rights reserved.

The CUORE-0 experiment searched for neutrinoless double beta decay in130Te using an array of 52 tellurium dioxide crystals, operated as bolometers at a temperature of 10 mK. It took data in the Gran Sasso National Laboratory (Italy) since March 2013 to March 2015. We present the results of a search for neutrinoless double beta decay in 9.8 kg-years130Te exposure that allowed us to set the most stringent limit to date on this half-life. The performance of the detector in terms of background and energy resolution is also reported.