Detecting Charged-Current Neutrino-Nucleus Interactions on Oxygen in a Heavy Water Cherenkov Detector

At Oak Ridge National Laboratory, the COHERENT collaboration has built a heavy water Cherenkov detector to measure the neutrino flux coming from the Spallation Neutron Source (SNS) via the scattering of neutrinos on deuterium nuclei. This detector is a steel cylinder with an inner acrylic vessel and twelve PMTs lining the inside of the top lid. The inner acrylic vessel holds heavy water and the space between the acrylic and steel vessels holds light water, acting as a tail-catcher region for Cherenkov radiation produced within the heavy water. The detector was fully completed and began taking measurements in the summer of 2023. Although this heavy water Cherenkov detector was built primarily to measure the SNS neutrino flux, it can also measure the cross section of neutrino-nucleus charged-current interactions on ¹⁶O nuclei. Charged-current ¹⁶O(ν_e, e⁻)X reactions produce electrons that emit Cherenkov radiation within the detector. The SNS is the world's most powerful pulsed source of accelerator-based neutrinos, which also happens to produce ν_e in a similar energy range to supernova neutrinos. Thus the measurement of this charged-current neutrino-oxygen reaction has implications for supernova neutrino detection. This neutrino interaction has also never been experimentally measured, and thus its measurement can be a test of nuclear models. This presentation describes methodology for detecting and measuring the cross section and event rate of this charged-current interaction between ν_e and ¹⁶O nuclei.