First Observation Of Coherent Elastic Neutrino-Nucleus Scattering
Coherent elastic neutrino-nucleus scattering (CE$ν$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$ν$NS is a low-energy nuclear recoil, which made its detection challenging. CE$ν$NS remained unobserved for over four decades. This thesis describes the experiment that resulted in a CE$ν$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$ν$NS signatures in energy and time, compatible with predictions from the Standard Model, were observed in high signal-to-background conditions. CE$ν$NS provides new opportunities to study neutrino properties, and enables the miniaturization of detectors.