Low Energy Neutrino-Nucleus Interactions at the Spallation Neutron Source

Abstract

There are few existing measurements of low energy neutrino-nucleus interactions. The COHERENT collaboration is seeking to measure several of these processes using the intense pulsed neutrinos produced at the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL). The primary process of interest to COHERENT is coherent elastic neutrino-nucleus scattering (CEvNS), a process predicted in 1974 but only first measured by COHERENT in 2017. In a CEvNS interaction, a neutrino elastically scatters off a nucleus, causing its nucleons to recoil in phase, leading to a large increase in the scattering cross section. The large cross section provides several potential applications of CEvNS, however the signature of interaction, a keV-scale nuclear recoil, can be difficult to detect.This thesis highlights experimental work to develop and measure neutrino-nucleus interactions on a variety of targets, including both CEvNS interactions and inelastic neutrino-nucleus interactions. This includes the development a ton-scale sodium-iodide scintillator array, a 185-kg prototype NaI detector, and analysis of neutrino-induced neutron detectors seeking to study unobserved neutrino-nucleus interactions on lead and iron. In addition, supporting measurements carried out at the Triangle Universities Nuclear Laboratory (TUNL) to measure quenching factors in NaI[Tl] are discussed.