Abstract
Transmission electron microscopy was used to study the effects of fission fragment irradiation on single crystalline gold films as a function of the fission‐fragment energy. It is found that the density of black spots increases as the average energy of the fission fragment decreases. The observations indicate that black spots are produced in displacement cascades initiated by energetic primaries. The results are consistent with a model based on the assumption that only those events are observed in which the primary energy is greater than 2.5×104 eV.