Pulse Shape Discrimination in CUPID-Mo using Principal Component Analysis

Abstract

Mo is a cryogenic detector array designed to search for neutrinoless double-beta decay (0𝜈𝛽𝛽) of 100 Mo. It uses 20 scintillating 100 Mo-enriched Li 2 MoO 4 bolometers instrumented with Ge light detectors to perform active suppression of 𝛼 backgrounds, drastically reducing the expected background in the 0𝜈𝛽𝛽 signal region. As a result, pileup events and small detector instabilities that mimic normal signals become non-negligible potential backgrounds. These types of events can in principle be eliminated based on their signal shapes, which are different from those of regular bolometric pulses. We show that a purely data-driven principal component analysis based approach is able to filter out these anomalous events, without the aid of detector response simulations.

Estimation of waveform deformation with the matched filter

“…However, a very good energy resolution and nearly zero background are needed for the signal identification. The LEGEND experiment, for example, identifies background events via their different pulse shapes [20,21], while pile-up events are expected to be the ultimate background of the CUPID experiment [22][23][24].…”