High energy ion tracks in solids

High energy ions dissipate most of their energy in electronic excitation rather than nuclear collision. Through this electronic excitation process, these ions produce their tracks in insulating or semiconducting materials. The observation of the structure of tracks is important in the development of the solid state detectors for high energy ions but also from the fundamental standpoint of elucidating the mechanism of track formation. The observation of the tracks of fission fragments in materials has been performed with electron microscopes, but it is difficult to perform quantitative experiment by systematically changing the energy, mass number and charge of incident particles. In this experiment, the specified and well collimated ion beam obtained from a tandem accelerator was irradiated. The electron microscopic observation of the evaporated films of germanium and silicon was performed, and the correlation between the size of the tracks and the energy deposition of incident ions was examined. The heavy ion track filter of polyvinylidene fluoride was made and examined. (Kako, I.)