Flux Limit of Cosmic-Ray Magnetic Monopoles from a Multiply Discriminating Superconducting Detector

Abstract

A multiply discriminating, three-loop superconducting monopole detector was operated for 1 yr. During this period 8523 h of data were accumulated. The sensing area averaged over solid angle for trajectories passing through a loop was 178 ${\mathrm{cm}}^2$. With inclusion of double-coincidence events from trajectories passing through the shield but not through a loop, the total sensing area averaged over solid angle was 1195 ${\mathrm{cm}}^2$. No candidate monopole events were observed; this leads to an upper limit on the flux of cosmic-ray magnetic monopoles of 5.0 × ${10}^{-12\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\mathrm{sr}}^{-1\mathrm{}}$ ${\mathrm{s}}^{-1\mathrm{}}$ with a 90% confidence level.