Michael Wagenpfeil Erlangen

Characterization of UV-sensitive SiPM for the nEXO experiment(pdf)

The nEXO experiment (next Enriched Xenon Observatory) will be a 5t LXe TPC for the search for the hypothetical neutrinoless double beta decay of Xe-136. The detector will use 4 m² of silicon photomultipliers (SiPM) operated at ca. -104 C. There are strong demands on xenon purity, radio purity and the SiPM performance to set the most stringent limits on the decay parameters. Detecting the 0vbb-decay would have wide-spread implications for neutrino physics. The SiPMs need to be sensitive to the vacuum-ultraviolet LXe scintillation light @175 nm which is not given for off-the shelf SiPMs. To meet the nEXO requirements - above all an energy resolution of 1% ? at the Q-value (2458 keV) - a decent SiPM performance is required, namely a photon detection efficiency of at least 15% at 175nm, a correlated avalanche probability of less than 20% and a low dark rate. We present current measurements with state-of-the-art SiPM devices as well as a method to investigate their behaviour in LXe.