Searches for magnetic monopoles[edit]
A number of attempts have been made to detect magnetic monopoles. One of the simpler ones is to use a loop of
superconducting wire to look for even tiny magnetic sources, a so-called "superconducting quantum interference device", or
SQUID. Given the predicted density, loops small enough to fit on a lab bench would expect to see about one monopole event per year. Although there have been tantalizing events recorded, in particular the event recorded by
Blas Cabrera on the night of February 14, 1982 (thus, sometimes referred to as the "
Valentine's DayMonopole"
[38]), there has never been reproducible evidence for the existence of magnetic monopoles.
[13] The lack of such events places an upper limit on the number of monopoles of about one monopole per 1029
nucleons.