Demonstration of MeV-scale physics in liquid argon time projection chambers using ArgoNeuT

MeV-scale energy depositions by low-energy photons produced in neutrino- argoninteractions have been identified and reconstructed in ArgoNeuT liquid argon time projection chamber(LArTPC) data. ArgoNeuT data collected on the NuMIbeam at Fermilabwere analyzed to select isolated low-energy depositions in the TPC volume. The total number, reconstructed energies and positions of these depositions have been compared to those from simulations of neutrino- argoninteractions using the FLUKA Monte Carlo generator. Measured features are consistent with energy depositions from photons produced by de-excitation of the neutrino's target nucleus and by inelastic scattering of primary neutrons produced by neutrino- argoninteractions. This study represents a successful reconstruction of physics at the MeV-scale in a LArTPC, a capability of crucial importance for detection and reconstruction of supernova and solar neutrinointeractions in future large LArTPCs.