Dark Matter search with bolometric detectors

In this Ph.D. work we developed a new trigger for the CUORE experiment that is sensitive to the signal shape. This trigger, based on the Optimum Filter algo- rithm, was tested on the four CUORE-like crystals of the second CUORE Crystals Validation Run (CCVR2), using a total exposure of 44 kg · d. The application to these data pushed the energy threshold from tens of keV down to the few keV region, an energy range that has never been available before in TeO2 bolometers. The detection efficiency has been evaluated by means of a dedicated run with external heaters and validated using Montecarlo, resulting in excess of 80%. We also developed a pulse shape algorithm to reject fake events induced by elec- tronics and mechanic vibrations, which populate the few keV region. Its application allows to cut a significative amount of noise events, maintaining the signal efficiency close to 100%. Analyzing the Optimum Triggered data, we observed a peak centered at about 4.7 keV in the energy spectra of the bolometers with the lowest threshold. Under the hypotesis that this line comes from the 123Te decay, we evaluated for the first time its half-life as (5.7 ± 0.6 (stat.) ± 0.6 (syst.)) · 1018 y. We also estimated a limit on Dark Matter interactions, that is similar to the one obtained in the past by MIBETA. Finally we estimated the sensitivity of CUORE and CUORE-0 to a Dark Matter modulation signal by means of toy Montecarlo, under the assumption that the background of the bolometers of these experiments will be the same of the CCVR2 ones. The resulting sensitivity plot shows that CUORE will be able to test the DAMA claim. This will be extremely important because, even if DAMA allowed region has been already excluded by several experiments, none of them was sensitive to the annual modulation effect. In this framework, CUORE could be the first experiment to look for modulation with a different experimental setup, providing a crucial cross-check of this controversial observation.