Assuming that dark matter particles interact with quarks via a GeV-scale mediator, we study dark matter production in fixed target collisions. The ensuing signal in a neutrino near detector consists of neutral-current events with an energy distributi
on peaked at higher values than the neutrino background. We find that for a $Z$ boson of mass around a few GeV that decays to dark matter particles, the dark matter beam produced by the Main Injector at Fermilab allows the exploration of a range of values for the gauge coupling that currently satisfy all experimental constraints. The NO$ u$A detector is well positioned for probing the presence of a dark matter beam, while future LBNF near-detectors would provide more sensitive probes.
