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 $2\times {10}^{-14}{\mathrm{cm}}^{-2}{\mathrm{s}}^{-1}{\mathrm{sr}}^{-1}$ at 90% C.L. for monopole speed $6\times {10}^{-4}<\mathrm{<ruby><rb>\beta </rb><rt>べーた</rt></ruby>}<5\times {10}^{-3}$ and mass greater than $5\times {10}^8\mathrm{GeV}$. Because of NOvA’s small overburden of 3 meters-water equivalent, this constraint covers a previously unexplored low-mass region.

• Received 10 September 2020
• Accepted 22 December 2020

DOI:https://doi.org/10.1103/PhysRevD.103.012007

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Published by the American Physical Society