|Towers are ~11×11 cm, the fiber bundle is ~6mm across. The SiPMs are 3x3mm, so we need some light guide to get from 6mm round to 3×3 square.
|A trigger plane is needed to cover a 2×2 stack of modules. We'll use the 16×19 mm scintillator bars we have from the dark photon detector.
|Readout is with the S13360-3050CS SiPMs from Hamamatsu