Search for Magnetic Monopoles Trapped in Matter

TL;DR

This study searched for magnetic monopoles trapped in various terrestrial materials using superconducting detectors but found no evidence, setting stringent upper limits on their abundance in matter.

Contribution

It is the first comprehensive search for magnetic monopoles in matter using superconducting induction techniques across diverse natural samples.

Findings

No monopoles detected in over 331 kg of samples.

Established an upper limit on monopole/nucleon ratio of <1.2×10^{-29}.

Demonstrated the effectiveness of superconducting induction detectors for monopole searches.

Abstract

There have been many searches for magnetic monopoles in flight, but few for monopoles in matter. We have searched for magnetic monopoles in meteorites, schists, ferromanganese nodules, iron ores and other materials. The detector was a superconducting induction coil connected to a SQUID (Superconducting Quantum Interference Device) with a room temperature bore 15 cm in diameter. We tested a total of more than 331 kg of material including 112 kg of meteorites. We found no monopole and conclude the overall monopole/nucleon ratio in the samples is $<1.2 \times 10^{-29}$ with a 90\% confidence level.