Limit on the flux of cosmic-ray magnetic monopoles from operation of an eight-loop superconducting detector

Abstract

An eight-loop superconducting magnetic monopole detector has been in continuous operation for 547 days, starting 4 March 1987. Its sensing area is 1.1 ${\mathrm{m}}^{2}$ for double-coincident events. The data, which contain no candidate events, set an upper limit of 7.2\ifmmode\times\else\texttimes\fi{}${10}^{\mathrm{\ensuremath{-}}13}$ ${\mathrm{cm}}^{\mathrm{\ensuremath{-}}2}$ ${\mathrm{s}}^{\mathrm{\ensuremath{-}}1}$ ${\mathrm{sr}}^{\mathrm{\ensuremath{-}}1}$ (90% confidence level) on the flux of monopoles of any mass and at any velocity passing through the Earth's surface.