Comments on "Direct measurement of the ionization quenching factor of nuclear recoils in germanium in the keV energy range"

Abstract

We examine a recent measurement of the quenching factor (QF) in germanium at 80 K, noticing a number of inconsistencies capable of affecting a claimed agreement with Lindhard's ion-stopping formalism in the sub-keV nuclear recoil energy regime. Namely, an underestimated uncertainty in the energy scale and a missing correction for a large instrumental non-linearity in this scale able to severely distort the QF behavior at low energy, favoring reduced values. The discussion is expanded to inspect the impact of QF model selection on a study of neutrino electromagnetic properties using CE$\nu$NS data that supports a non-zero electric charge at the 3.5 $\sigma$ level.