Particle Discrimination in TeO${}_2$ Bolometers using Light Detectors read out by Transition Edge Sensors

An active discrimination of the dominant $\alpha$-background is the prerequisite for future neutrinoless double-beta decay experiments based on TeO${}_2$ bolometers. We investigate such $\alpha$-particle rejection in cryogenic TeO${}_2$ bolometers by the detection of Cherenkov light. For a setup consisting of a massive TeO${}_2$ 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/$\gamma$- and $\alpha$-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 ${}^{130}$Te a separation of the means of the two populations of 3.7 times their width.