The front-end readout for CUORICINO, an array of macro-bolometers and MIBETA, an array of μ-bolometers

We present the performances of two 92% enriched 130 TeO 2 crystals operated as thermal bolometers in view of a next generation experiment to search for neutrinoless double beta decay of 130 Te. The crystals, 435 g each, show an energy resolution, evaluated at the 2615 keV γ-line of 208 Tl, of 6.5 and 4.3 keV FWHM. The only observable internal radioactive contamination arises from 238 U (15 and 8 µBq/kg, respectively). The internal activity of the most problematic nuclei for neutrinoless double beta decay, 226 Ra and 228 Th, are both evaluated as <3.1 µBq/kg for one crystal and <2.3 µBq/kg for the second. Thanks to the readout of the weak Cherenkov light emitted by β/γ particles by means of Neganov-Luke bolometric light detectors we were able to perform an eventby-event identification of β/γ events with a 95% acceptance level, while establishing a rejection factor of 98.21 % and 99.99 % for α particles.

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“…The detector was cooled down to a temperature of ∼12 mK. A complete description of the set-up and the electronics can be found in [31,32,33].…”

Section: Experimental Set-upmentioning

confidence: 99%

Enriched TeO2 bolometers with active particle discrimination: Towards the CUPID experiment

et al. 2017

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“…The electronics is described in Refs. [44][45][46][47][48][49][50]. Data are saved on disk using a custom DAQ software package [51].…”

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confidence: 99%

Final Result of CUPID-0 Phase-I in the Search for the Se82 Neutrinoless Double- β Decay

Azzolini¹,

Beeman²,

Bellini³

et al. 2019

Phys. Rev. Lett.

104

100

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CUPID-0 is the first pilot experiment of CUPID, a next-generation project for the measurement of neutrinoless double beta decay (0νDBD) with scintillating bolometers. The detector, consisting of 24 enriched and 2 natural ZnSe crystals, has been taking data at Laboratori Nazionali del Gran Sasso from June 2017 to December 2018, collecting a 82 Se exposure of 5.29 kg×yr. In this paper we present the phase-I results in the search for 0νDBD. We demonstrate that the technology implemented by CUPID-0 allows us to reach the lowest background for calorimetric experiments: (3.5 +1.0 −0.9 ) × 10 −3 counts/(keV kg yr). Monitoring 3.88×10 25 82 Se nuclei×yr we reach a 90% credible interval median sensitivity of T 0ν 1/2 > 5.0 × 10 24 yr and set the most stringent limit on the half-life of 82 Se 0νDBD: T 0ν 1/2 > 3.5 × 10 24 yr (90% credible interval), corresponding to m ββ < (311-638) meV depending on the nuclear matrix element calculations.Nowadays, neutrinoless double beta decay (0νDBD) is considered one of the most sensitive probes for Physics Beyond the Standard Model. This hypothetical nuclear transition foresees the simultaneous decay of two neutrons into protons and electrons without the emission of neutrinos [1]. Its detection would prove the nonconservation of the total lepton number, setting an important milestone for leptogenesis and baryogenesis theories [2]. The observation of 0νDBD would give precious insights also in Particle Physics, as this transition can occur only if neutrinos coincide with their own antiparticles, according to the Majorana hypothesis. As a consequence, its detection would allow to establish the fundamental nature of these particles [3]. Furthermore, if the mechanism at the basis of 0νDBD is the exchange of light Majorana neutrinos, the half-life of the transition (T 0ν 1/2 ) would scale as T 0ν 1/2 ∝ m −2 ββ , where the parameter m ββ (effective Majorana neutrino mass) is a superimposition of the neutrino mass eigenvalues m i weighted by the elements of the neutrino mixing matrix (U ei ): m ββ =| i U 2 ei m i | [4]. Thus, a measurement of T 0ν 1/2 would also allow to constrain the absolute mass scale of neutrinos.The increasing interest in the search for 0νDBD motivated a huge international effort in the development of several technologies [5-9] to study some of the candidate isotopes: elements with even atomic number and even neutron number, for which the single beta decay is strongly forbidden by energy conservation law. These experiments are now envisioning next-generation detectors to probe half-lives exceeding 10 27 yr and, thus, the whole range of the inverted hierarchy region of neutrino masses, whose lower bound is at m ββ ∼10 meV. The main handles to improve the sensitivity are the detector exposure, the background in the region of interest and the energy resolution [10]. To ensure a competitive discovery potential, next-generation detectors will need more than 10 27 emitters (hundreds of kg of source), a background as close as possible to zero in 5-10 years of data-taking, and a...

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“…In the so called cold electronics , applied to the remaining 24 crystals, the preamplifier is located in a box at ∼100 K near the detector to reduce the noise due to microphonics [44], which would be very dangerous when searching for WIMPS. More details on read-out electronics and DAQ are reported in [40].…”

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confidence: 99%

New Limit on the NeutrinolessββDecay ofTe130

Arnaboldi¹,

Artusa²,

Avignone³

et al. 2005

Phys. Rev. Lett.

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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...

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The front-end readout for CUORICINO, an array of macro-bolometers and MIBETA, an array of μ-bolometers

Cited by 54 publications

References 2 publications

Enriched TeO2 bolometers with active particle discrimination: Towards the CUPID experiment

Enriched TeO2 bolometers with active particle discrimination: Towards the CUPID experiment

Final Result of CUPID-0 Phase-I in the Search for the Se82 Neutrinoless Double- β Decay

New Limit on the NeutrinolessββDecay ofTe130

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