  MeV-scale energy depositions by low-energy photons produced in neutrino-argon
interactions have been identified and reconstructed in ArgoNeuT liquid argon
time projection chamber (LArTPC) data. ArgoNeuT data collected on the NuMI beam
at Fermilab were 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-argon
interactions 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-argon interactions. 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 neutrino
interactions in future large LArTPCs.
