Flux Limit on Cosmic-Ray Magnetic Monopoles from a Large Area Induction Detector

The design and performance of a superconducting induction detector with two 60-cm-diameter superconducting loops is presented. During eight months of data taking, no candidate events were observed, and an upper limit on the flux of cosmic-ray magnetic monopoles of about 6.7 x 10 to the -12th/sq cm sr sec (90-percent confidence level) is set. The detector demonstrates the possibility of operating large induction detectors in ambient magnetic fields greater than 1 mG.