Pulse shape discrimination in CUPID-Mo using principal component analysis

Abstract

<jats:title>Abstract</jats:title> <jats:p>CUPID-Mo is a cryogenic detector array designed to search for neutrinoless double-beta decay (0νββ) of <jats:sup>100</jats:sup>Mo. It uses 20 scintillating <jats:sup>100</jats:sup>Mo-enriched Li<jats:sub>2</jats:sub>MoO<jats:sub>4</jats:sub> 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.</jats:p>