Probing neutrino millicharges at the European Spallation Source

TL;DR

This paper evaluates the potential of future detectors at the European Spallation Source to measure neutrino millicharges via coherent elastic neutrino-nucleus scattering, highlighting the superior sensitivity of germanium detectors and the impact of electron scattering processes.

Contribution

It demonstrates the feasibility of probing neutrino millicharges with upcoming detectors, providing sensitivity estimates and comparing different detection materials and processes.

Findings

Germanium detectors offer the best sensitivity to neutrino millicharges.

Including electron scattering improves sensitivity to about 10^{-10} e.

Detectors can constrain neutrino millicharges down to 10^{-9} to 10^{-10} e.

Abstract

We study the potential of a set of future detectors, proposed to be located at the European Spallation Source (ESS), to probe neutrino millicharges through coherent elastic neutrino-nucleus scattering. In particular, we focus on detectors with similar characteristics as those that are under development for operation at the ESS, including detection technologies based on cesium iodine, germanium, and noble gases. Under the considered conditions, we show that the Ge detector, with a lighter nuclear target mass with respect to CsI and to a noble gas like Xe, is more efficient to constrain neutrino millicharges, reaching a sensitivity of $\sim 10^{-9}e$ for diagonal neutrino millicharges, and $\sim 10^{-8}e$ for the transition ones. In addition, we study the effects of including electron scattering processes for the CsI detector, achieving an expected sensitivity of $\sim 10^{-10} e$ for the diagonal millicharges.