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

TL;DR

This paper critically examines a recent germanium quenching factor measurement, highlighting potential inaccuracies and their implications for neutrino property studies, emphasizing the importance of proper calibration and model selection.

Contribution

It identifies key issues in the measurement process and discusses how these affect interpretations of neutrino electromagnetic properties.

Findings

Potential underestimation of energy scale uncertainty

Instrumental non-linearity significantly impacts low-energy QF

QF model choice influences neutrino electromagnetic property conclusions

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.