Cryogenic scintillation veto for $0\nu 2\beta$ bolometric experiments: from a concept to BINGO prototypes

Achieving a very low, ideally zero, background level, along with ensuring high energy resolution and detection efficiency, are the main tasks in the development of the next generation of experiments to search for neutrinoless double beta ($0\nu 2\beta$) decay. Cryogenic scintillating bolometers meet these basic requirements perfectly. The main ideas pursued in the BINGO (Bi-Isotope $0\nu 2\beta$ Next Generation Observatory) project are the use of a cryogenic scintillation anti-coincidence veto, the minimization of the detector array passive materials, and the use of advanced cryogenic light detectors to reduce backgrounds from surface radioactivity and random signal coincidences. This article presents simulation results for detectors based on Li${}_2$MoO${}_4$ or TeO${}_2$ surrounded by a 5-cm-thick active Bi${}_4$Ge${}_3$O${}_{12}$ scintillation veto, demonstrating the potential to reduce the background by up to a factor of ${10}^3$, depending on the source location and the type of radionuclide. We further present results from the first cryogenic tests of a small scale prototype with respect to the feasibility of this proposed veto.