First Measurement of Electron Neutrino Scattering Cross Section on Argon

We report the first electron neutrino cross section measurements on argon, based on data collected by the ArgoNeuT experiment running in the GeV-scale NuMI beamline at Fermilab. A flux-averaged ${\nu }_e+{\bar{\nu }}_e$ total and a lepton angle differential cross section are extracted using 13 ${\nu }_e$ and ${\bar{\nu }}_e$ events identified with fully-automated selection and reconstruction. We employ electromagnetic-induced shower characterization and analysis tools developed to identify ${\nu }_e\mathrm{/}{\bar{\nu }}_e$-like events among complex interaction topologies present in ArgoNeuT data ($\langle E_{\bar{\nu}e} \rangle = 4.3$GeVand$\langle E{\nu_e} \rangle = 10.5$ GeV). The techniques are widely applicable to searches for electron-flavor appearance at short- and long-baseline using liquid argon time projection chamber technology. Notably, the data-driven studies of GeV-scale ${\nu }_e\mathrm{/}{\bar{\nu }}_e$ interactions presented in this Letter probe an energy regime relevant for future DUNE oscillation physics.