Research Papers in Physics and Astronomy


Date of this Version

October 1959


Published in Physical Review 116:1 (October 1, 1959), pp. 236-238. Copyright ©1959 The American Physical Society. Used by permission. Online at URL:


A magnetic monopole may be detected by its deflection in an electric field or by the character of the ionization it produces. The electric deflection experiment may be performed in a helium bubble chamber where helical (or spiral) tracks whose axes are parallel to the D-lines would be certain evidence for the discovery of the monopole. Previous studies of the ionization have emphasized that the Bragg tail would be missing from a monopole track, as compared to a charged particle. This conclusion must be modified because of the thin-down of tracks of heavy nuclei. The tracks of heavy nuclei thicken up and then thin down as they approach the end of their range. The tracks of monopoles are wedge-shaped, thinning down continuously as they approach the end of their range. Since the track width is due to knock-on electrons, or delta rays, any search for the monopole using this criterion must be conducted with electron-sensitive emulsions.

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