Final CONUS results on coherent elastic neutrino-nucleus scattering at the Brokdorf reactor

TL;DR

The Conus experiment measured coherent elastic neutrino-nucleus scattering at the Brokdorf reactor, achieving low thresholds and setting new limits close to standard model predictions, improving previous constraints significantly.

Contribution

This work provides the final results of the Conus experiment with improved sensitivity and constraints on neutrino interactions near a nuclear reactor.

Findings

New limit of less than 0.34 events/kg/day on neutrino interactions

Achieved ionization thresholds of 210 eV in germanium detectors

Results are within a factor of 2 of standard model predictions

Abstract

The Conus experiment studies coherent elastic neutrino-nucleus scattering in four 1 kg germanium spectrometers. Low ionization energy thresholds of 210 eV were achieved. The detectors were operated inside an optimized shield at the Brokdorf nuclear power plant which provided a reactor antineutrino flux of up to 2.3$\cdot$10$^{13}$\,cm$^{-2}$s$^{-1}$. In the final phase of data collection at this site, the constraints on the neutrino interaction rate were improved by an order of magnitude as compared to the previous Conus analysis. The new limit of less than 0.34 signal events kg$^{-1}$\,d$^{-1}$ is within a factor 2 of the rate predicted by the standard model. This constraint is discussed in the context of conflicting measurements and results from another reactor neutrino experiment using similar technology.