Occurrence of a Fission-Dust Particle in a Nuclear Emulsion

Abstract

In the microscopic examination of an Ilford Nuclear Research emulsion exposed to cosmic radiation in the stratosphere, an unusual radioactive inclusion was noted. As shown in the photomicrograph (Fig. 1), the embedded particle is strongly beta-active and when examined under conditions of higher resolution the tracks originate from an opaque, nearly spherical granule with a diameter of 5–10 microns. One alpha-particle track with a recorded range of 14 ± 1 microns is associated with the embedded grain. The fused appearance of the inclusion, together with its beta- and alpha-activity, suggests that it may have originated from an atomic weapons detonation.