Coherent production of protons by neutrinos

The reaction ν + N → ν + N + γ, involving the coherent emission of a photon in a neutrino-nucleus collision, can produce 'single shower' events that simulate the reaction ν + e → ν + e. The ratio of coherent photons to electrons (for an 27Al target) is estimated to be 40% at Esub(ν) = 2 GeV and 10% at Esub(ν) = 20 GeV. We examine the extent to which the 'excess' of showers seen in the Aachen-Padova experiment could be understood by this mechanism. (orig.)