BINGO: Background reduction techniques for 0ν2β bolometric experiments.

BINGO is a project dedicated to explore new methods for background reduction in experiments searching for 0ν2β decay. It is based on bolometers, one of the most promising techniques to search for 0ν2β. CUORE and CUPID-Mo/0 are the main bolometric experiments that have illustrated the most relevant limiting factors on sensitivity the bolometers are facing. Surface αs are the main source of background in CUORE, and this contribution has been mitigated in CUPID-Mo/0 using dual heat-light channels, i.e., a main absorber embedding the 2β decay isotope facing a light detector. In this case, surface α rejection is achieved thanks to the lower α light output compared to β/γ. However, there are still other background components that limit the sensitivity of the experiments, such as pile-ups due to random coincidences of physical events, external γ background and β surface radioactivity. BINGO's proposed technology aims at reducing the background index down to 10−5 counts/(keV kg yr) in the region of interest, thus boosting the sensitivity on the effective Majorana neutrino mass. This can be achieved by: (i) having a revolutionary detector assembly with a reduction in the passive materials facing the detector; (ii) increasing the light detector sensitivity thanks to Neganov-Luke amplification; (iii) using an active shield, based on BGO scintillators with bolometric light detector readout to surround the experimental volume. The main text describes the listed approaches in detail, as well as the recent results of prototype tests. [ABSTRACT FROM AUTHOR]