Flux Limit of Cosmic-Ray Magnetic Monopoles from a Fully Coincident Superconducting Induction Detector

Abstract

A superconducting inductive monopole detector consisting of six independent high-order planar gradiometers placed on the six faces of a 15×15×60-${\mathrm{cm}}^3$ rectangular parallelepiped was operated from November 1983 to February 1985. This detector had a fully coincident-detection area of 0.1 ${\mathrm{m}}^2$. No monopoles were detected during an accumulated 9100 h of observation time, setting an upper limit of 5.5×${10}^{-12\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\mathrm{s}}^{-1\mathrm{}}$ ${\mathrm{sr}}^{-1\mathrm{}}$ (90% C.L.) for the cosmic-ray monopole flux.