Search for Slowly Moving Massive Magnetic Monopoles

An array of plastic scintillation counters was used to search for slowly moving, weakly ionizing particles between April and September 1982. The electronically defined velocity acceptance was 1×10^-4c to 3×10^-2c. The sensitivity of the 2.7-m²-sr detector was gradually increased until the threshold reached about 0.12Iₘᵢₙ. The decrease of scintillator excitation with velocity very likely introduced a lower velocity cutoff near 1.4×10^-4c. The flux limit for the high-sensitivity runs corresponds to an aperture-solid-angle-time product of ${(5×{}{10}^{{-}12}{{0ex}{0ex}}{cm}^{{-}2}{{0ex}{0ex}}{sr}^{{-}1}{{0ex}{0ex}}{s}^{{-}1})}^{{-}1}$.