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

The first results are reported on the limit for neutrinoless double decay of 130Te obtained with the new bolometric experiment CUORICINO. The set-up consists of 44 cubic crystals of natural TeO2, 5 cm on the side and 18 crystals of 3×3×6 cm3. Four of these latter crystals are made with isotopically enriched materials: two in 128Te and two others in 130Te. With a sensitive mass of 40 kg, our array is by far the most massive running cryogenic detector to search for rare events. The array is operated at a temperature of 10 mK in a dilution refrigerator under a heavy shield in the Gran Sasso Underground Laboratory at a depth of about 3500 m.w.e. The counting rate in the region of neutrinoless double beta decay is 0.2 counts keV−1 kg−1 y−1, among the lowest in this type of experiment. No evidence for neutrinoless double beta decay is found with the present statistics obtained in about three months with a live time of 72%. The corresponding lower limit for the lifetime of this process is of 5.5×1023 years at 90% C.L. The corresponding limit for the effective neutrino mass ranges between 0.37 to 1.9 eV depending on the theoretically calculated nuclear matrix elements used. This constraint is the most restrictive one except those obtained with Ge diodes, and is comparable to them

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The CUORE Crystal Validation Runs (CCVRs) have been carried out since the end of 2008 at the Gran Sasso National Laboratories, in order to test the performances and the radiopurity of the TeO 2 crystals produced at SICCAS (Shanghai Institute of Ceramics, Chinese Academy of Sciences) for the CUORE experiment. In this work the results of the first 5 validation runs are presented. Results have been obtained for bulk contaminations and surface contaminations from several nuclides. An extrapolation to the CUORE background has been performed.

We report the present results of CUORICINO a cryogenic experiment on neutrinoless double beta decay (DBD) of 130 Te consisting of an array of 62 crystals of TeO2 with a total active mass of 40.7 kg. The array is framed inside of a dilution refrigerator, heavily shielded against environmental radioactivity and high-energy neutrons, and operated at a temperature of ∼8 mK in the Gran Sasso Underground Laboratory. Temperature pulses induced by particle interacting in the crystals are recorded and measured by means of Neutron Transmutation Doped thermistors. The gain of each bolometer is stabilized with voltage pulses developed by a high stability pulse generator across heater resistors put in thermal contact with the absorber. The calibration is performed by means of two thoriated wires routinely inserted in the set-up. No evidence for a peak indicating neutrinoless DBD of 130 Te is detected and a 90 % C.L. lower limit of 1.8×10 24 years is set for the lifetime of this process. Taking largely into account the uncertainties in the theoretical values of nuclear matrix elements, this implies an upper boud on the effective mass of the electron neutrino ranging from 0.2 to 1.1 eV. This sensitivity is similar to those of the 76 Ge experiments.PACS numbers: 23.40.B; 11.30.F;14.60.PGreat interest was stimulated in recent years in neutrinoless double beta decay (DBD) as a consequence of the observation of neutrino oscillations [1,2,3,4,5,6], proving that the differences between the squares of the neutrino mass eigenvalues is different from zero. This indicates that the mass m ν of at least one neutrino is finite, but does not allow the determination of its absolute value.The value of the sum of the masses of the neutrinos of the three flavors has been constrained to values from 0.7 to 1.7 eV from the WMAP full sky microwave map together with the survey of the 2dF galaxy redshift [7,8,9,10,11]. A claim for a non zero value of 0.64 eV has also been proposed [12]. These values are more constraining than upper limits of 2.2 eV for m ν obtained so far in experiments on single beta decay, but they are strongly model dependent and therefore less robust than laboratory measurements. Limits of ∼0.2 eV are expected in KATRIN experiment [13]. If neutrinos are Majorana particles more stringent constraints, or a positive value for the effective neutrino mass, can be obtained by neutrinoless DBD. In this lepton violating process, a nucleus (A,Z) decays into (A,Z+2) with the emission of two electrons and no neutrino. This leads to a peak in the sum energy spectrum of the two electrons. The decay rate of this process would be proportional to the square of the effective neutrino mass | m ν | , which can be expressed in terms of the elements of the neutrino mixing matrix as follows:where e iφ2 and e iφ3 are the Majorana CP-phases (± 1 for CP conservation), m 1,2,3 are the Majorana neutrino mass eigenvalues and U L ej are the coefficients of the Pontecorvo-Maki-Nakagawa-Sakata (PMNS) neutrino mixing matrix, determined from neutrino oscillati...