A convincing observation of neutrino-less double beta decay (0vDBD) relies on the possibility of operating high-energy resolution detectors in background-free conditions. Scintillating cryogenic ...calorimeters are one of the most promising tools to fulfill the requirements for a next-generation experiment. Several steps have been taken to demonstrate the maturity of this technique, starting form the successful experience of CUPID-0. The CUPID-0 experiment collected almost 10 kg y of exposure, running 26 Zn82Se crystals during two years of continuous detector operation. The complete rejection of the dominant α background was demonstrated, measuring the lowest counting rate in the region of interest for this technique. Furthermore, the most stringent limit on the 82Se 0vDBD was established. In this contribution we present the final results of CUPID-0 phase-I, including a detailed model of the background and the measurement of the 2vDBD half-life.
In the framework of the CUPID-0 experiment, a numbers of ZnSe single crystals were produced and subjected to different thermal treatments, and later tested as cryogenic scintillating bolometers. We ...have found that a specific thermal treatment (24 hours under argon atmosphere at 900 °C) has a strong impact on some properties of ZnSe crystals (amplitude of signal, light yield, specific resistivity) and most interestingly, changes the quenching factor for alpha particles from values > 1 to values < 1. Thus such thermal treatment opens the possibility to modify this experimental parameter for a various applications.
A search for axioelectric absorption of solar axions produced in the
p
+
d
→
3
He
+
γ
(
5.5
MeV
)
reaction has been performed with a BGO detector placed in a low-background setup. A model-independent ...limit on the combination of axion–nucleon and axion–electron coupling constants has been obtained:
|
g
A
e
×
g
A
N
3
|
<
1.9
×
10
-
10
for 90 % confidence level. The constraint of the axion–electron coupling constant has been obtained for hadronic axion with masses of (0.1–1) MeV:
|
g
A
e
|
≤
(
0.96
-
8.2
)
×
10
-
8
.
The aim of this work was to develop a methodological approach based on Monte Carlo code for the neutronic analysis of the first core configuration of the TRIGA Mark II research reactor of the ...University of Pavia and the validation of the results by benchmarking with the experimental and operational data reported in the reactor Fist Criticality Final Report.
The neutron analysis was realised by means of the 3-D continuous-energy Monte Carlo code MCNP4C. The reactor model implemented represents in good detail all core components and allows the description of different core and fuel configurations with good versatility. Continuous-energy cross section data from ENDF/B-VI and ENDF/B-V and S(
α,
β) scattering functions from the ENDF/B-VI library were used. The results of the MCNP simulations and the experimental values show a very good agreement proving the goodness of the model.
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 R&D activity performed during the last years proved the potential of ZnSe scintillating bolometers to the search for neutrino-less double beta decay, motivating the realization of the first ...large-mass experiment based on this technology: CUPID-0. The isotopic enrichment in Formula: see textSe, the ZnFormula: see textSe crystals growth, as well as the light detectors production have been accomplished, and the experiment is now in construction at Laboratori Nazionali del Gran Sasso (Italy). In this paper we present the results obtained testing the first three ZnFormula: see textSe crystals operated as scintillating bolometers, and we prove that their performance in terms of energy resolution, background rejection capability and intrinsic radio-purity complies with the requirements of CUPID-0.
A methodological approach based on Monte Carlo code for the neutronic analysis of the TRIGA Mark II research reactor of the University of Pavia in the configuration of cold and clean nuclear fuel is ...presented. The complete implementation of the code is based on the construction characteristics with the validation of the results obtained by benchmarking the experimental and operational data reported in the reactor Fist Criticality Final Report. The 3-D continuous-energy Monte Carlo code MCNP5 was used. The description of the geometrical structure of the reactor core and the fuel configuration were designed with great accuracy and good detail. The comparison between simulated and measured data allows the creation of a complete reconstruction model of the TRIGA Mark II reactor.
•Monte Carlo model of a TRIGA Mark II reactor.•Reproduction of the reactor configuration after the first startup.•Simulation of critical configurations and control rod calibration curves.•Statistical and systematic error were accounted for.•Good agreement with experimental data proves model reliability.
The Cryogenic Underground Observatory for Rare Events (CUORE) will search for the 0vββ decay in 130Te using a cryogenic array of TeO2 bolometers, operated at a base temperature of ~10mK. CUORE will ...consist of a closely packed array of 19 towers each containing 52 crystals, for a total mass of 741kg. The detector assembly is hosted in one of the largest cryostats ever constructed and will be cooled down to base temperature using a custom-built cryogen free dilution refrigerator. The CUORE cryostat along with the pulse tube based dilution refrigerator has been already commissioned at Laboratori Nazionali del Gran Sasso (LNGS) and a record base temperature, on a cubic meter scale, of ~6mK was achieved during one of the integration runs. We present the results from integration runs, characterizing the system and the cooling performance of the dilution refrigerator, effectively showcasing its stability at base temperature for the expected thermal load.
The idea of using a scintillating bolometer was first suggested for solar neutrino experiments in 1989. After many years of developments, now we are able to exploit this experimental technique, based ...on the calorimetric approach with cryogenic particle detectors, to investigate rare events such as Neutrinoless Double Beta Decay and interaction of Dark Matter candidates. The possibility to have high resolution detectors in which a very large part of the natural background can be discriminated with respect to the weak expected signal is very appealing. The goal to distinguish the different types of interactions in the detector can be achieved by means of scintillating bolometer. The simultaneous read-out of the heat and scintillation signals made with two independent bolometers enable this precious feature leading to possible background free experiment. In the frame of the LUCIFER project we report on how exploiting this technique to investigate Double Beta Decay for different isotope candidates. Moreover we demonstrate how scintillating bolometers are suited for investigating other rare events such as α decays of long living isotopes of lead and bismuth.
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