The COHERENT Tonne-scale LAr CEvNS Detector and neutron backgrounds

Coherent elastic neutrino-nucleus scattering (CEvNS) has been detected in a 24 kg single-phase liquid argon (LAr) scintillator detector. To obtain an event rate 20 times that of the 24 kg detector with a low threshold, the 750 kg LAr scintillator detector COH-Ar-750 has been designed by the COHERENT collaboration to be deployed at the Spallation Neutron Source at Oak Ridge National Laboratory. Work on the cryogenics system and light collection is ongoing. The 750 kg detector will be sensitive to non-standard neutrino interactions, nuclear form factors, inelastic charged-current and neutral-current events, and to light accelerator-produced dark matter. A large source of background for these measurements are beam related neutrons (BRNs). To measure BRNs, set of four 5L EJ301 liquid scintillator detectors on a mobile cart was used to measure timing and energy information at different locations along neutrino alley. The energy and timing results for these measurements will be presented here, along with other updates on the development of COH-Ar-750.