AFM observations of latent fission tracks on surfaces: amorphous SiO2 and quartz

Preliminary results of a systematic AFM experimental investigation of the surface ‘track’ effects produced by the passage of fission fragments from a californium (²⁵²Cf) source into amorphous SiO₂ and quartz are described. Fission fragments from the source were collimated using a 10 μm thick aluminum foil and comprised fragments with the usual binary distribution of energies—light and heavy—79.4 and 103.8 MeV. Irradiations and AFM measurements were carried out in air at normal room temperature and pressure. Remarkably high sputtering yields/fragment were discovered, and in the case of crystalline quartz the ejecta was found to be arranged in an ordered manner. A brief discussion is given of a part likely to be played by electronic energy loss induced Coulomb explosion of target atoms for each point of fragment entry.