Particle discrimination in TeO2 bolometers using light detectors read out by transition edge sensors

An active discrimination of the dominant αα-background is the prerequisite for future neutrinoless double-beta decay experiments based on TeO2 bolometers. We investigate such αα-particle rejection in cryogenic TeO2 bolometers by the detection of Cherenkov light. For a setup consisting of a massive TeO2 crystal (285 g) and a separate cryogenic light detector, both using transition edge sensors as temperature sensors operated at around 10 mK, we obtain an event-by-event identification of e/γγ- and αα-events. We find in the energy interval ranging from 2400 keV to 2800 keV and covering the Q-value of the neutrinoless double-beta decay of 130Te a separation of the means of the two populations of 3.7 times their width.