Evidence for Detection of a Moving Magnetic Monopole

A very heavy particle passed through a balloon-borne stack of Cherenkov film, emulsion, and Lexan sheets. In 33 Lexan sheets it produced tracks expected of either a nucleus with 125Z137 and β0.92 or a magnetic monopole with $g=137e$. Its track structure in emulsion indicated it was moving downward with β=0.5_-0.05+0.1 and was either a nucleus with Z≈80 or a monopole with $g=137e$. These facts strongly favor identification of the particle as a magnetic monopole of strength $g=137e$ and mass >200mₚ.