Search

CUPID is a next-generation tonne-scale bolometric neutrinoless double beta decay experiment that will probe the Majorana nature of neutrinos and discover lepton number violation in case of observation of this singular process. CUPID will be built on experience, expertise and lessons learned in CUORE and will be installed in the current CUORE infra-structure in the Gran Sasso underground laboratory. The CUPID detector technology, successfully tested in the CUPID-Mo experiment, is based on scintillating bolometers of Li2MoO4 enriched in the isotope of interest 100Mo. In order to achieve its ambitious science goals, the CUPID collaboration aims to reduce the backgrounds in the region of interest by a factor 100 with respect to CUORE. This performance will be achieved by introducing the high efficient α/β discrimination demonstrated by the CUPID-0 and CUPID-Mo experiments, and using a high transition energy double beta decay nucleus such as 100Mo to minimize the impact of the gamma background. CUPID will consist of about 1500 hybrid heat-light detectors for a total isotope mass of 250 kg. The CUPID scientific reach is supported by a detailed and safe background model based on CUORE, CUPID-Mo and CUPID-0 results. The required performances have already been demonstrated and will be presented.

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. 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.

CUORE is a 741 kg array of TeO2bolometers for the search of neutrinoless double beta decay of130Te. The detector is being constructed at the Laboratori Nazionali del Gran Sasso, Italy, where it will start taking data in 2015. If the target background of 0.01 counts/(keV.kg.y) will be reached, in five years of data taking CUORE will have a 1σ half life sensitivity of 1026y. CUORE-0 is a smaller experiment constructed to test and demonstrate the performances expected for CUORE. The detector is a single tower of 52 CUORE-like bolometers that started taking data in spring 2013. The status and perspectives of CUORE will be discussed, and the first CUORE-0 data will be presented.

The CUORE (Cryogenic Underground Observatory for Rare Events) experiment is an array of 741 kg of TeO2bolometers to search for neutrinoless double beta decay (ββ0ν) of130Te. The detector is being constructed at the Laboratori Nazionali del Gran Sasso (Italy) where it will start operation in 2015. To test and demonstrate the possibility of realising such a large scale bolometric detector, a prototype (CUORE-0) has been realised. The CUORE-0 detector is a single tower of 52 CUORE-like bolometers. CUORE-0 data taking started in Spring 2013. The status of CUORE and the first CUORE-0 data are here reported.

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.

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.

The CUORE experiment is a ton-scale array of TeO 2 cryogenic bolometers located at the underground Laboratori Nazionali del Gran Sasso of Istituto Nazionale di Fisica Nucleare (INFN), in Italy. The CUORE detector consists of 988 crystals operated as source and detector at a base temperature of ∼ 10 mK. Such cryogenic temperature is reached and maintained by means of a custom built cryogen-free dilution cryostat, designed with the aim of minimizing the vibrational noise and the environmental radioactivity. The primary goal of CUORE is the search for neutrinoless double beta decay of 130 Te , but thanks to its large target mass and ultra-low background it is suitable for the study of other rare processes as well, such as the neutrinoless double beta decay of 128 Te . This tellurium isotope is an attractive candidate for the search of this process, due to its high natural isotopic abundance of 31.75%. The transition energy at (866.7 ± 0.7) keV lies in a highly populated region of the energy spectrum, dominated by the contribution of the two-neutrino double beta decay of 130 Te . As the first ton-scale infrastructure operating cryogenic TeO 2 bolometers in stable conditions, CUORE is able to achieve a factor > 10 higher sensitivity to the neutrinoless double beta decay of this isotope with respect to past direct experiments. [ABSTRACT FROM AUTHOR]

The CUORE experiment is a large bolometric array searching for the lepton number violating neutrino-less double beta decay ( 0 ν β β ) in the isotope 130 Te . In this work we present the latest results on two searches for the double beta decay (DBD) of 130 Te to the first 0 2 + excited state of 130 Xe : the 0 ν β β decay and the Standard Model-allowed two-neutrinos double beta decay ( 2 ν β β ). 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 ν = 5.6 × 10 24 yr for the 0 ν β β decay and S 1 / 2 2 ν = 2.1 × 10 24 yr for the 2 ν β β 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 ν > 5.9 × 10 24 yr for the 0 ν β β mode and (T 1 / 2) 0 2 + 2 ν > 1.3 × 10 24 yr for the 2 ν β β 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. [ABSTRACT FROM AUTHOR]

The 1-ton-scale CUORE detector is made of 988 TeO 2 crystals operated as cryogenic bolometers at a working temperature of ∼ 10 mK . In order to provide the necessary cooling power at 4 K stage, a total of five pulse tube (PT) refrigerators are used. The PTs make the cryogenic system reliable and stable, but have the downside that mechanical vibrations at low frequencies (1.4 Hz and related harmonics) are injected into the experimental apparatus. An active noise cancellation technique has been developed in order to reduce such effect by taking advantage from the coherent interference of the pressure oscillations originated by the different PTs. The technique that will be presented consists in controlling the relative phases of the pressure waves running inside the CUORE PT lines, in order to achieve the lowest detector noise. By reducing the power of PT harmonics by a factor up to 10 4 , it drastically suppresses the overall noise RMS on the CUORE detector. In the following, we demonstrate the reliability and effectiveness of the technique, showing that the optimization of the detector noise level is possible in different experimental conditions. [ABSTRACT FROM AUTHOR]

The Cryogenic Underground Observatory for Rare Events (CUORE) is a bolometric experiment for neutrinoless double-beta decay in 130Te search, currently taking data at the underground facility of Laboratori Nazionali del Gran Sasso (LNGS). The CUORE cryostat successfully cooled down a mass of about 1 ton at ∼7mK, delivering a uniform and constant base temperature. This result marks a fundamental milestone in low-temperature detector techniques, opening the path for future ton-scale bolometric experiments searching for rare events. In this paper, we present the CUORE cryogenic infrastructure, briefly describing its critical subsystems. [ABSTRACT FROM AUTHOR]

The Cryogenic Underground Observatory for Rare Events (CUORE) experiment at Gran Sasso National Laboratory of INFN searches for neutrinoless double beta decay using TeO 2 crystals as cryogenic bolometers. The sensitivity of the measurement heavily depends on the energy resolution of the detector, therefore the success of the experiment stands on the capability to provide an extremely low noise environment. One of the most relevant sources of noise are the mechanical vibrations induced by the five Pulse Tube cryocoolers used on the cryogenic system which houses the detectors. To address this problem, we developed a system to control the relative phases of the pulse tube pressure oscillations, in order to achieve coherent superposition of the mechanical vibrations transmitted to the detectors. In the following, we describe this method and report on the results in applying it to the CUORE system. [ABSTRACT FROM AUTHOR]

TeO2 bolometers have been used for many years to search for neutrinoless double beta decay in Te. CUORE, a tonne-scale TeO2 detector array, recently published the most sensitive limit on the half-life, 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 Te and the hypothesized electron capture in Te), 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. [ABSTRACT FROM AUTHOR]

CUORE is a tonne-scale cryogenic detector operating at the Laboratori Nazionali del Gran Sasso (LNGS) that uses tellurium dioxide bolometers to search for neutrinoless double-beta decay of $$^{130}$$ Te. CUORE is also suitable to search for low energy rare events such as solar axions or WIMP scattering, thanks to its ultra-low background and large target mass. However, to conduct such sensitive searches requires improving the energy threshold to 10 keV. In this paper, we describe the analysis techniques developed for the low energy analysis of CUORE-like detectors, using the data acquired from November 2013 to March 2015 by CUORE-0, a single-tower prototype designed to validate the assembly procedure and new cleaning techniques of CUORE. We explain the energy threshold optimization, continuous monitoring of the trigger efficiency, data and event selection, and energy calibration at low energies in detail. We also present the low energy background spectrum of CUORE-0 below $$60 \, \mathrm {keV}$$ . Finally, we report the sensitivity of CUORE to WIMP annual modulation using the CUORE-0 energy threshold and background, as well as an estimate of the uncertainty on the nuclear quenching factor from nuclear recoils inCUORE-0. [ABSTRACT FROM AUTHOR]

Due to their excellent energy resolution values and the vast choice of possible materials, bolometric detectors are currently widely used in the physics of rare events. A limiting aspect for bolometers rises from their inability to discriminate among radiation types or surface from bulk events. It has been demonstrated that the main limitation to sensitivity for purely bolometric detectors is represented by surface alpha contaminations, causing a continuous background that cannot be discriminated. A new scintillation-based technique for the rejection of surface alpha background in non-scintillating bolometric experiments is proposed in this work. The idea is to combine a scintillating and a high sensitivity photon detector with a non-scintillating absorber. We present results showing the possibility to reject events due to alpha decay at or nearby the surface of the crystal. [ABSTRACT FROM AUTHOR]

Next-generation experiments searching for neutrinoless double-beta decay must be sensitive to a Majorana neutrino mass as low as 10 $$\mathrm {~meV}$$ . CUORE , an array of 988 TeO $$_2$$ bolometers being commissioned at Laboratori Nazionali del Gran Sasso, features an expected sensitivity of 50-130 $$\mathrm {~meV}$$ at 90 % C.L. The background is expected to be dominated by $$\alpha $$ radioactivity, and can be in principle removed by detecting the small amount of Cherenkov light emitted by the $$\beta $$ signal. The Cryogenic wide-Area Light Detectors with Excellent Resolution project aims at developing a small prototype experiment consisting of TeO $$_2$$ bolometers coupled to high-sensitivity light detectors based on kinetic inductance detectors. The R&D is focused on the light detectors in view of the implementation in a next-generation neutrinoless double-beta decay experiment. [ABSTRACT FROM AUTHOR]

Neutrinoless double-beta (0νββ) decay is a hypothesized lepton-number-violating process that offers the only known means of asserting the possible Majorana nature of neutrino mass. The Cryogenic Underground Observatory for Rare Events (CUORE) is an upcoming experiment designed to search for 0νββ decay of 130Te using an array of 988 TeO2 crystal bolometers operated at 10 mK. The detector will contain 206 kg of 130Te and have an average energy resolution of 5 keV; the projected 0νββ decay half-life sensitivity after five years of livetime is 1.6 × 1026 y at 1σ (9.5 × 1025 y at the 90% confidence level), which corresponds to an upper limit on the effective Majorana mass in the range 40–100 meV (50–130 meV). In this paper, we review the experimental techniques used in CUORE as well as its current status and anticipated physics reach. [ABSTRACT FROM AUTHOR]

A challenging aspect of the next generation detector for rare events searches (i.e. neutrinoless double beta decay and dark matter searches) is the reduction of the background in the region of interest that can mimic the expected signals. In the field of thermal detectors, which have a leading role in rare events searches thanks to their excellent energy resolution and to the wide choice of absorber materials, the background coming from surface contaminations is frequently dominant. A background surface rejection detector is a scintillation-based approach for tagging this type of background. We discuss the innovative application of this technique in non-scintillating thermal detectors. We will report on the performances of the prototype bolometric detector, realized to prove the feasibility of this new technique. [ABSTRACT FROM AUTHOR]

The CUORE (Cryogenic Underground Observatory for Rare Events) experiment will search for neutrinoless double beta decay in $$^{130}$$ Te. Observation of the process would unambiguously establish that neutrinos are Majorana particles as well as provide information about the absolute neutrino mass scale and mass hierarchy.The CUORE setup will consist of an array of 988 tellurium dioxide crystals (containing 206 kg of $$^{130}$$ Te in total), operated as bolometers at a temperature of $$\sim $$ 10 mK. The experiment is now under construction at the Gran Sasso National Laboratory in Italy. As a first step towards CUORE, a tower (CUORE-0) has been assembled and is taking data. Here a detailed description of the CUORE-0 tower and its performance is reported. The status of the CUORE experiment and its expected sensitivity will then be discussed. [ABSTRACT FROM AUTHOR]

Large-mass arrays of bolometers proved to be good detectors for neutrinoless double beta decay (0 $$\nu $$ DBD) and dark matter searches. CUORE and LUCIFER are bolometric 0 $$\nu $$ DBD experiments that will start to take data in 2015 at Laboratori Nazionali del Gran Sasso in Italy. The sensitivity of CUORE could be increased by removing the background due to $$\alpha $$ particles, by detecting the small amount of Čerenkov light ( $$\sim $$ 100 eV) emitted by the $$\beta $$ s' signal and not by $$\alpha $$ s. LUCIFER could be extended to detect also dark matter, provided that the background from $$\beta $$ / $$\gamma $$ particles ( $$\sim $$ 100 eV of scintillation light) is discriminated from nuclear recoils of about 10 keV energy (no light). We have recently started to develop light detectors for CUORE, LUCIFER and similar bolometric experiments. The aim is to obtain detectors with an active area of $$5\times 5~\mathrm{cm}^2$$ (the face of bolometric crystals), operating at 10 mK, and with an energy resolution at the baseline below 20 eV RMS. We have chosen to develop phonon-mediated detectors with KID sensors. We are currently testing the first prototypes. [ABSTRACT FROM AUTHOR]

CUORE-0 is a cryogenic detector that uses an array of tellurium dioxide bolometers to search for neutrinoless double-beta decay of $$\mathrm {^{130}Te}$$ . We present the first data analysis with $$7.1 \,\mathrm {kg\cdot y}$$ of total $$\mathrm {TeO_2}$$ exposure focusing on background measurements and energy resolution. The background rates in the neutrinoless double-beta decay region of interest (2.47 to $$2.57 \,\mathrm {MeV}$$ ) and in the $$\alpha $$ background-dominated region (2.70 to $$3.90\,\mathrm {MeV}$$ ) have been measured to be $${0.071\pm 0.011}$$ and $${0.019\pm 0.002}\,\mathrm {counts/(keV\cdot kg\cdot y)}$$ , respectively. The latter result represents a factor of 6 improvement from a predecessor experiment, Cuoricino. The results verify our understanding of the background sources in CUORE-0, which is the basis of extrapolations to the full CUORE detector. The obtained energy resolution (full width at half maximum) in the region of interest is $$5.7\,\mathrm {keV}$$ . Based on the measured background rate and energy resolution in the region of interest, CUORE-0 half-life sensitivity is expected to surpass the observed lower bound of Cuoricino with one year of live time. [ABSTRACT FROM AUTHOR]

Large-mass bolometers are today extensively used for dark matter and double beta decay searches, in both cases the ultimate experimental sensitivity is defined by the background level reached in such devices. The most common background sources and the techniques used for their identification and reduction are here reviewed, with a particular focus on double beta decay searches. The relevant role played by Monte Carlo simulations in this field is discussed. As a real case, the background optimization in the MiDBD experiment is described. [ABSTRACT FROM AUTHOR]

CUORICINO is an array of 62 TeO2 bolometers with a total mass of 40.7 kg (11.2 kg of 130Te), operated at about 10 mK to search for ββ(0 ν) of 130Te. The detectors are organized as a 14-story tower and intended as a slightly modified version of one of the 19 towers of the CUORE project, a proposed tightly packed array of 988 TeO2 bolometers (741 kg of total mass of TeO2) for ultralow-background searches on neutrinoless double-beta decay, cold dark matter, solar axions, and rare nuclear decays. Started in April 2003 at the Laboratori Nazionali del Gran Sasso (LNGS), CUORICINO data taking was stopped in November 2003 to repair the readout wiring system of the 62 bolometers. Restarted in spring 2004, CUORICINO is presently the most sensitive running experiment on neutrinoless double-beta decay. No evidence for ββ(0 ν) decay has been found so far and a new lower limit, T ≥ 1.8 × 1024 yr (90% C.L.), is set, corresponding to 〈 m ν〉 ≤ 0.2–1.1 eV, depending on the theoretical nuclear matrix elements used in the analysis. Detector performance, operational procedures, and background analysis results are reviewed. The expected performance and sensitivity of CUORE is also discussed. [ABSTRACT FROM AUTHOR]

We present our circuit solution for the implementation of a very simple temperature stabilization system of an array of 62 large mass bolometric detectors, CUORICINO. The implemented instrument exploits one of the front-end channels to close the feedback loop between a thermistor and a heather, both of them located on the detector holder in the refrigerating system. A very compact layout was developed that avoids any possible presence of EMI interference, which would otherwise be introduced if a commercial instrument were adopted. The stabilized temperature is obtained exploiting the offset correcting circuit of the remotely programmable front-end channel to autogene rate the reference operating point for the feedback loop. Thanks to the adopted configuration, the instability of the cryogenic apparatus, which induced a drift corresponding to about 50 keV/day, was reduced to less than about 0.5 keV/day. To model the system behavior, we have reformulated the bolometer theory of operation using the concept of a feedback network. The obtained results will be shown. [ABSTRACT FROM AUTHOR]

The CUORICINO ββ-decay detector is an array of 62 TeO2 bolometers; 44 are 5 × 5 × 5-cm crystals made with natural tellurium (33.8% 130Te). There are 18, 3 × 3 × 6-cm crystals, 14 of which are made of natural tellurium, 2 are isotopically enriched to 75% in 130Te, and 2 are enriched to 82.3% in 128Te. The total mass of 130Te is ∼11 kg. The background rate is 0.23±0.04 counts/keV/kg/yr in the energy interval 2480 to 2600 keV. During the cooling process, some of the wires became disconnected and only 32 of the large and 16 of the smaller crystals could be read out. The data presented here come from 29 of the 5 × 5 × 5-cm crystals containing 6.2 kg of 130Te. The new limit on the half-life is T0ν1/2 ≥ 5 × 1023 yr, corresponding to an effective Majorana mass of the electron neutrino 〈mν〉 between 0.42 and 2.05 eV, depending on the nuclear model used to analyze the data.© 2004 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

CUORE is a proposed tightly packed array of 1000 TeO[sub 2] bolometers, each being a cube 5 cm on a side with a mass of 750 g. The array consists of 25 vertical towers, arranged in a square of 5 towers by 5 towers, each containing ten layers of four crystals. The design of the detector is optimized for ultralow-background searches for neutrinoless double beta decay of [sup 130]Te (33.8% abundance), cold dark matter, solar axions, and rare nuclear decays. A preliminary experiment involving 20 crystals of various sizes (MIBETA) 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.© 2003 MAIK “Nauka / Interperiodica”. [ABSTRACT FROM AUTHOR]

Describes the front-end electronics designed for the readout of the CUORICINO experiment's array of bolometers. System description; Features of the bolomoters; System noise performance of the bolometers.

At the end of 2001 the Milano Double Beta Decay (MI-DBD) experiment on double beta decay of 130Te has been completed. The project Cryogenic Underground Observatory for Rare Events (CUORE), proposed as a natural extension of MI-DBD, will be a tightly packed array of 1000 TeO2 bolometers, each being a cube 5 cm on a side with a mass of 790 g. The array will consists of 25 vertical towers, arranged in a square of 5 towers by 5 towers, each containing 10 layers of 4 crystals. A single CUORE tower has been constructed as a smaller scale experiment called CUORICINO. The technical feasibility of CUORE is now being tested in CUORICINO, running since few weeks. The CUORICINO experiment consists of 44 TeO2 detectors 5×5×5 cm3 and 18 TeO2 detectors 3×3×6 cm3 for a total mass of approximately 41 kg. An analysis of the detector performances is presented together with the new limit obtained on neutrinoless double beta decay of 130Te. [Copyright &y& Elsevier]

The CUPID-0 detector hosted at the Laboratori Nazionali del Gran Sasso, Italy, is the first large array of enriched scintillating cryogenic detectors for the investigation of 82Se neutrinoless double-beta decay (0νββ). CUPID-0 aims at measuring a background index in the region of interest (RoI) for 0νββ at the level of 10-3 counts/(keV kg years), the lowest value ever measured using cryogenic detectors. CUPID-0 operates an array of Zn82Se scintillating bolometers coupled with bolometric light detectors, with a state of the art technology for background suppression and thorough protocols and procedures for the detector preparation and construction. In this paper, the different phases of the detector design and construction will be presented, from the material selection (for the absorber production) to the new and innovative detector structure. The successful construction of the detector lead to promising preliminary detector performance which is discussed here. [ABSTRACT FROM AUTHOR]