# First Observation Of Coherent Elastic Neutrino-Nucleus Scattering

## TL;DR

This paper reports the first observation of coherent elastic neutrino-nucleus scattering (CEvNS) with a high-confidence experiment using a CsI[Na] detector exposed to neutrinos from the Spallation Neutron Source, confirming Standard Model predictions.

## Contribution

It presents the first experimental detection of CEvNS, overcoming previous detection challenges and validating theoretical predictions.

## Key findings

- CEvNS observed at 6.7-sigma confidence level
- Detected signals match Standard Model predictions
- Demonstrated potential for neutrino property studies and detector miniaturization

## Abstract

Coherent elastic neutrino-nucleus scattering (CE$\nu$NS) has the largest predicted cross-section of all low-energy neutrino couplings. However, as a neutral-current interaction, the only experimental signature of CE$\nu$NS is a low-energy nuclear recoil, which made its detection challenging. CE$\nu$NS remained unobserved for over four decades. This thesis describes the experiment that resulted in a CE$\nu$NS observation at a 6.7-sigma confidence level. A low-background, 14.6-kg CsI[Na] scintillator was exposed to the neutrino emissions from the Spallation Neutron Source at Oak Ridge National Laboratory. Characteristic CE$\nu$NS signatures in energy and time, compatible with predictions from the Standard Model, were observed in high signal-to-background conditions. CE$\nu$NS provides new opportunities to study neutrino properties, and enables the miniaturization of detectors.