Abstract At the Deep Underground Neutrino Experiment (DUNE). a proton beam hits a fixed target leading to large production rates of mesons. These mesons can decay and potentially provide a source of long-lived neutral fermions. Examples of such long-lived fermions are heavy neutral leptons which can mix with the standard-model active neutrinos. https://www.bekindtopets.com/special-offer-Sticker-Skywhalepapa-Missy-Minzy-mega-find/