COHERENT Search for Neutrino-Induced Neutrons at the Spallation Neutron Source

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, and perhaps the most dangerous is the background arising from inelastic neutrino-nucleus interactions in the detector shielding. Inelastic neutrino-nucleus interactions excite a nucleus that then de-excite by neutron emission. Such neutrons can interact in a detector and produce nuclear recoils that mimic nuclear recoils produced by CEvNS and also 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. Lead is of particular interest because it is major component of the HALO Supernovae Neutrino detector. The COHERENT Collaboration 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 Pb-208.