A Ton-Scale NaI Detector for Neutrino-Nucleus Scattering Measurements

The COHERENT collaboration measures coherent elastic neutrino-nucleus scattering (CEvNS) in multiple materials to map the neutron number squared dependence predicted by the Standard Model. The collaboration will deploy a ton-scale NaI[Tl] scintillation crystal based modular detector array, initially with about 2 T of detector material at Oak Ridge National Laboratory. Sodium is the lightest element in the suite of COHERENT detectors with a low cross section, but energetic nuclear recoil observable. The large-mass NaI[Tl] detector has the potential to measure both CEvNS and charged current electron neutrino inelastic scattering cross sections on I-127 with neutrino energy < 55 MeV. The CEvNS measurement enables a comparison to results from the CsI detector and the inelastic measurement is sensitive to gA quenching relevant for neutrinoless double-beta decay calculations. Extensive studies from simulations and the currently deployed NaI-185kg prototype informed the ton-scale design and models.