Search for Neutrino-Induced Neutron Production in Pb-208 at SNS

Neutrino-nucleus interactions serve as a possible probe to study the nucleus and weak interactions. The COHERENT Collaboration seeks to observe the N² dependence of the coherent elastic neutrino-nucleus scattering (CEvNS) and continues taking data for the precision measurement of the CEvNS cross-section for multiple nuclei. A large effort has been dedicated to understanding backgrounds present. Perhaps the most elusive is the background arising from inelastic ν-nucleus interactions in the detector shielding. Inelastic ν-nucleus interactions excite a nucleus that then de-excites by particle emission. Neutrino-induced neutrons (NIN) are of special interest because these neutrons can interact to produce nuclear recoils that mimic nuclear recoils produced by CEvNS and share the same timing distribution as CEvNS events. The cross-section for heavy nuclei such as Lead and Iron is predicted to be quite large but has not been measured and theoretical calculations have large uncertainty. NIN production on Pb is also of interest as a proposed mechanism to observe supernova neutrinos as in the HALO experiment. COHERENT is constructing and characterizing capture-gated neutron detectors for deployment in 980 kg of lead target to measure the inelastic neutrino-nucleus cross-section in Pb208.