Search for slow magnetic monopoles with the NOvA detector on the surface

Abstract

We report a search for a magnetic monopole component of the cosmic-ray flux in a 95-day exposure of the NOvA experiment's Far Detector, a 14 kt segmented liquid scintillator detector designed primarily to observe GeV-scale electron neutrinos. No events consistent with monopoles were observed, setting an upper limit on the flux of 2×10-14 cm-2 s-1 sr-1 at 90% C.L. for monopole speed 6×10-4 < β < 5×10-3 and mass greater than 5×108 GeV. Because of NOvA's small overburden of 3 meters-water equivalent, this constraint covers a previously unexplored low-mass region.