TeO$_2$ bolometers with Cherenkov signal tagging: towards   next-generation neutrinoless double beta decay experiments
  CUORE, an array of 988 TeO$_2$ bolometers, is about to be one of the most sensitive experiments searching for neutrinoless double-beta decay. Its sensitivity could be further improved by removing the background from $\alpha$ radioactivity. A few years ago it has been pointed out that the signal from $\beta$s can be tagged by detecting the emitted Cherenkov light, which is not produced by $\alpha$s. In this paper we confirm this possibility. For the first time we measured the Cherenkov light emitted by a CUORE crystal, and found it to be 100 eV at the $Q$-value of the decay. To completely reject the $\alpha$ background, we compute that one needs light detectors with baseline noise below 20 eV RMS, a value which is 3-4 times smaller than the average noise of the bolometric light detectors we are using. We point out that an improved light detector technology must be developed to obtain TeO$_2$ bolometric experiments able to probe the inverted hierarchy of neutrino masses. 
N. Casali, M. Vignati, J.W. Beeman, F.Bellini, L. Cardani, I. Dafinei,   S. Di Domizio, F. Ferroni, L. Gironi, S. Nagorny, F...
physics.ins-det hep-ex nucl-ex