8 research outputs found
The commissioning of the CUORE experiment: the mini-tower run
CUORE is a ton-scale experiment approaching the data taking phase in Gran Sasso National Laboratory. Its primary goal is to search for the neutrinoless double-beta decay in 130Te using 988 crystals of tellurim dioxide. The crystals are operated as bolometers at about 10 mK taking advantage of one of the largest dilution cryostat ever built. Concluded in March 2016, the cryostat commissioning consisted in a sequence of cool down runs each one integrating new parts of the apparatus. The last run was performed with the fully configured cryostat and the thermal load at 4 K reached the impressive mass of about 14 tons. During that run the base temperature of 6.3 mK was reached and maintained for more than 70 days. An array of 8 crystals, called mini-tower, was used to check bolometers operation, readout electronics and DAQ. Results will be presented in terms of cooling power, electronic noise, energy resolution and preliminary background measurements
Results from the Cuore Experiment
The Cryogenic Underground Observatory for Rare Events (CUORE) is the first bolometric experiment searching for neutrinoless double beta decay that has been able to reach the 1-ton scale. The detector consists of an array of 988 TeO2 crystals arranged in a cylindrical compact structure of 19 towers, each of them made of 52 crystals. The construction of the experiment was completed in August 2016 and the data taking started in spring 2017 after a period of commissioning and tests. In this work we present the neutrinoless double beta decay results of CUORE from examining a total TeO2 exposure of 86.3kg yr, characterized by an effective energy resolution of 7.7 keV FWHM and a background in the region of interest of 0.014 counts/ (keV kg yr). In this physics run, CUORE placed a lower limit on the decay half- life of neutrinoless double beta decay of 130Te > 1.3.1025 yr (90% C. L.). Moreover, an analysis of the background of the experiment is presented as well as the measurement of the 130Te 2vo3p decay with a resulting half- life of T2 2. [7.9 :- 0.1 (stat.) :- 0.2 (syst.)] x 10(20) yr which is the most precise measurement of the half- life and compatible with previous results
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Searching for the 0νββ Decay of 130Te with the Ton-Scale CUORE Bolometer Array
CUORE---the Cryogenic Underground Observatory for Rare Events---is an experiment searching for the neutrinoless double-beta () decay of Te, based at the Laboratori Nazionali del Gran Sasso in Italy. The detector consists of 988 555 cm TeO crystals operated as bolometers at temperatures of 10 mK inside the world's largest and most powerful dilution refrigerator. CUORE began physics data collection in the spring of 2017, and has recently released its first limit on the decay half-life of Te from 24 kg y isotope exposure (2 months live time). This result---T^{0\nu}_{1/2} > 1.5 \cdot 10^{25} y (Bayesian) and T^{0\nu}_{1/2} > 2.3 \cdot 10^{25} y (Frequentist) at C.L.---is the most stringent to date and, together with two alternative analyses necessary to calculate it, forms the centerpiece of this thesis. In the future, with five years of live time, CUORE is projected to reach a median sensitivity of y on this half-life. Besides the main physics conclusions, in this work I present an analysis modeling the spectral line shape of the bolometer, which is used for constructing the region of interest fit PDF. Additionally, I discuss the major CUORE hardware projects to which I have contributed in a significant way. Specifically, these are our world-leading cryostat, a cryogenic feedback temperature control system, a radon-free detector installation environment, and a room temperature detector calibration system
Thermal conductivity measurements of PTFE and Al2O3 ceramic at sub-Kelvin temperatures
The design of low temperature bolometric detectors for rare event searches necessitates careful selection and characterization of structural materials based on their thermal properties. We measure the thermal conductivities of polytetrafluoroethylene (PTFE) and Al2O3 ceramic (alumina) in the temperature ranges of 0.17–0.43 K and 0.1–1.3 K, respectively. For the former, we observe a quadratic temperature dependence across the entire measured range. For the latter, we see a cubic dependence on temperature above 0.3 K, with a linear contribution below that temperature. This paper presents our measurement techniques, results, and theoretical discussions
CUORE: first results and prospects
International audienceCUORE is the first bolometric tonne-scale experiment aiming at the investigation of neutrinoless double-beta (02) decay of Te. The cryogenic commissioning followed by the detector installation and cool down took place during 2016. After the optimisation of all the detectors, the data-taking started in spring 2017. We report about the results of the first dataset acquired in May, which led to a limit on the 02 half-life of Te of 6.610 yr. An upgrade of CUORE, named CUPID, is planned to improve the 02-decay sensitivity via passive and active background reduction and crystal enrichment. Some technologies for CUPID are currently under study and two of them are presented here, involving the detection of Cherenkov and scintillation light emitted by enriched TeO and LiMoO crystals respectively. This will allow us to reject the currently dominant a background