FIRST RESULTS FROM A SEA LEVEL SEARCH FOR SUPERMASSIVE MAGNETIC MONOPOLES

The authors describe a search for supermassive slowly moving magnetic monopoles employing a single thick slab of naphthalene-doped acrylic scintillator. Slow, massive particles produce scintillation pulses of unusually long duration in the thick slab and can thus be distinguished from the large flux of relativistic muons that penetrate the detector at sea level. The current limit on the flux of monopoles is 4.1 x 10/sup -13/ cm/sup -2/ sr/sup -1/ s/sup -1/ (1sigma) for velocities 6 x 10/sup -4/c< or approx. =V<2.1 x 10/sup -3/c.