New magnetic monopole flux limits from the IMB proton decay detector

An improved limit on the flux of magnetic monopoles in the vicinity of the solar system is obtained, assuming that monopoles strongly catalyze nucleon decay (the Rubakov-Callan effect). Flux limits are presented for monopole velocities from ${10}^{-5\mathrm{}}c$ to ${10}^{-1\mathrm{}}c$ and for monopole-nucleon cross sections between ${10}^{-27\mathrm{}}$ ${\mathrm{cm}}^2$ and ${10}^{-21\mathrm{}}$ ${\mathrm{cm}}^2$. For a representative velocity $\beta \approx {10}^{-3\mathrm{}}$, and cross section $\sigma \approx {10}^{-24\mathrm{}}$ ${\mathrm{cm}}^2$, we obtain a limit $F_m<2.7\mathrm{}\times {10}^{-15\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\mathrm{sr}}^{-1\mathrm{}}$ ${\sec }^{-1\mathrm{}}$ and for $\sigma \approx {10}^{-25\mathrm{}}$ ${\mathrm{cm}}^2$, $F_m<1.0\mathrm{}\times {10}^{-15\mathrm{}}$ ${\mathrm{cm}}^{-2\mathrm{}}$ ${\mathrm{sr}}^{-1\mathrm{}}$ ${\sec }^{-1\mathrm{}}$ at 90% C.L.