Tagging Muon Induced Backgrounds in CUORE and CUPID*

CUPID, The CUORE Upgrade with Particle IDentification, is a proposed ton-scale search for neutrinoless double-beta decay located in Gran Sasso National Laboratory (LNGS). Building off the expertise and infrastructure of CUORE, the Cryogenic Underground Observatory for Rare Events, CUPID will improve discovery sensitivities by using an array of ¹⁰⁰Mo scintillating bolometers. LNGS is located 1400 m underground, which provides 3400 m.w.e of overburden, reducing the muon rate in the CUPID detector by a factor of 10⁶. Still, after planned upgrades such as particle identification, cosmogenic muons are projected to be CUPID’s most significant background, with ~2 muons/hour expected in the crystals. An active muon tagging system will mitigate this muon background. The system under development is a modular design of plastic scintillating panels with scintillating fiber, readout by SiPM detectors. The muon tagger must be highly compact to fit into the space constraints around the CUPID cryostat, and the tagger needs to be integrated into the CUPID DAQ and analysis framework. The progress towards designing this system with the highest efficiency, uniformity, and light collection within the constraints of CUPID will be discussed in this talk.