Characterization of a VUV-sensitive Silicon Photomultiplier for the nEXO experiment

The future nEXO experiment will use about 4 m² of SiPMs for the detection of the VUV (vacuum ultraviolet) scintillation light (λ = 175 nm) from LXe to search for the neutrinoless double beta (0νββ) decay of ¹³⁶Xe. Besides suffering from correlated avalanches, such as crosstalk and afterpulsing, most commercially available SiPMs are not sensitive to UV light. The core criteria, for having an energy resolution of about 1 % (σ) at the Q-value of the 0νββ decay of ¹³⁶Xe at 2457.8 keV, are a photon detection efficiency (PDE) of at least 15 % at 175 nm and a correlated avalanche probability of less than 20 %. We present measurements with a new device dedicated to detect VUV light. These SiPMs were investigated at -100 C both in the absence of light as well as using Xe scintillation light with respect to the requirements by the nEXO experiment.