When passing through some substances, heavy ionizing particles break the chemi­cal bonds and produce damaged channels. The diameter of these channels is about 5 nm; however, their diameter can be augmented to as large as 10 qm using chemi­cal development. In amorphous substances, the tracks are round, assuming that the ionizing particles enter the substance perpendicularly. In crystalline substances, the shape of the tracks fit the crystal lattice. The density of the tracks is propor­tional to the intensity of the radiation. Solid-state detectors can be used to measure the energy of the particles because the diameter of the tracks is proportional to the energy of the particles, providing that the procedures are done strictly under the same conditions.

In Figure 14.11, the tracks of the alpha particles emitted by 252Cf (6.1 MeV) are shown. Moreover, tracks of the heavy particles are shown in Figures 13.4 and 13.6.

Figure 14.11 Tracks of the alpha particles emitted by 252Cf (6.1 MeV). (Thanks to Dr. Istvan Csige, Department of Environmental Physics, University of Debrecen— Institute of Nuclear Research, Hungary, for the photograph.)

The basic characteristics of the most important solid-state detectors are summa­rized in Table 14.1. The plastic detectors are developed by 6 mol/dm3 of NaOH or KOH. Glass and silicate (such as mica) detectors are developed by hydrogen fluoride.

An application of solid-state detectors was presented in Section 4.3.3. The minerals also record nuclear processes that occur spontaneously in nature.