New constraints on coherent elastic neutrino-nucleus scattering by the nuGeN experiment

TL;DR

The nuGeN experiment searches for coherent elastic neutrino-nucleus scattering near a nuclear reactor, setting new upper limits on the event rate with a low-threshold germanium detector, but finds no significant signal.

Contribution

First deployment of a low-threshold germanium detector at a nuclear reactor to search for CEvNS, providing new upper limits on the scattering rate.

Findings

No statistically significant CEvNS signal detected.

Established new upper limits on CEvNS event rate.

Demonstrated the detector's capability at high antineutrino flux.

Abstract

The nuGeN experiment searches for coherent elastic neutrino-nucleus scattering (CEvNS) at the Kalinin Nuclear Power Plant. A 1.41-kg high-purity low-threshold germanium detector surrounded by active and passive shielding is deployed at the minimal distance of 11.1 m allowed by the lifting mechanism from the center of reactor core, utilizing one of the highest antineutrino fluxes among the competing experiments. The direct comparison of the count rates obtained during reactor-ON and reactor-OFF periods with the energy threshold of 0.29~keV$_{ee}$ shows no statistically significant difference. New upper limits on the number of CEvNS events are evaluated on the basis of the residual ON$-$OFF count rate spectrum.