During the one of the commissioning runs in Sptember 2014 at LNGS, the CUORE cryostat has reached a temperature of about 6 mK. The base temperature was maintained for about 15 days. In this run the system had all the copper shields in place with the cooling provided by the Dilution Unit and the Pulse Tubes.
The 6 mK temperature was attained on the Mixing Chamber stage with the copper shield in place (about 400 kg of copper, enclosing an approximate volume of 1 m3). The cryogenic system commissioning progressed through a staged approach where components were added step by step: the wires, the lead shields, the fast precooling system, the calibration system, and, finally, the detectors were added.
The detector installation was completed in 2016 and the first cooling down of the CUORE experiment was successfully completed in January 2017. The detectors reached a base temperature of 8 mK. Since then, excluding few initial maintenance stops, the CUORE refrigerator has been running continously allowing to carry out the planned CUORE neutrinoless double beta decays search.
The CUORE refrigerator cooling a 1 ton detector to less than 10 mK sets a world record for mass and temperature reached with a cryogen-free system.
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