Emission of heavy fragments in nuclear explosions

Abstract

Observations have been made on the energetic nuclear fragments emitted in ‘giant’ cosmic-ray stars.The disintegrations were produced in the heavy nuclei of Ilford C2 and G5 emulsions exposed at high altitude. Methods are described for the identification of the fragments, both stable and unstable, with charges between three and ten units. It is found that fragment emission may be interpreted in terms of an asymmetric fission process, which is highly probable when the nuclear excitation energy becomes comparable with the binding energy. The average kinetic energies of the fragments are considerably greater than those to be expected from the Coulomb repulsion, a fact which may be explained in terms of specifically long-range nuclear forces. The fragments exhibit a peculiar tendency to be emitted in directions perpendicular to the incident star-producing particle.The mass of the emitted fragment does not depend appreciably on the size of star. At present there appears to be no comprehensive theoretical explanation of the precise mechanism of emission of such particles.