CUPID: CUORE (Cryogenic Underground Observatory for Rare Events) Upgrade with Particle IDentification

Abstract: CUPID is a proposed future ton-scale bolometric neutrinoless double beta decay ($0\nu\beta\beta$) experiment to probe the Majorana nature of neutrinos and discover Lepton Number Violation in the so-called inverted hierarchy region of the neutrino mass. CUPID will be built on experience, expertise and lessons learned in CUORE, and will exploit the current CUORE infrastructure as much as possible. In order to achieve its ambitious science goals, CUPID aims to increase the source mass and dramatically reduce the backgrounds in the region of interest. This requires isotopic enrichment, upgraded purification and crystallization procedures, new detector technologies, a stricter material selection, and possibly new shielding concepts with respect to the state of the art deployed in CUORE. This document reviews the science goals of CUPID, defines the scope for the near-term R&D activities, and presents a roadmap towards mounting this next-generation experiment. A separate document discusses the extensive R&D program in more detail.